Title of Invention	A COMPOSITION AND METHOD FOR COLOR IMPROVEMENT OF NITROXYL CONTANING POLYMERS
Abstract	The invention relates to a composition comprising, a) at least one oligomer, cooligomer, polymer or copolymer or blends thereof, containing a stable free nitroxyl radical ; and b) a reducing agent; with the proviso that the composition is essentially free of a polymerizable monomer. A further subject is a process for improving the color of an oligomer, cooligomer, polymer or copolymer or blends thereof, containing a stable free nitroxyl radical by adding a reducing agent to said polymer and heating said mixture to above the glass temperature in case of amorphous polymers or above the melting point in case of crystalline or semi-crystalline polymers.

Title of Invention

A COMPOSITION AND METHOD FOR COLOR IMPROVEMENT OF NITROXYL CONTANING POLYMERS

Abstract

The invention relates to a composition comprising, a) at least one oligomer, cooligomer, polymer or copolymer or blends thereof, containing a stable free nitroxyl radical ; and b) a reducing agent; with the proviso that the composition is essentially free of a polymerizable monomer. A further subject is a process for improving the color of an oligomer, cooligomer, polymer or copolymer or blends thereof, containing a stable free nitroxyl radical by adding a reducing agent to said polymer and heating said mixture to above the glass temperature in case of amorphous polymers or above the melting point in case of crystalline or semi-crystalline polymers.

Full Text	The invention relates to a composition and process for color improvement of nitroxyl or nitroxyl ether containing polymers. Stable free nitrify radicals or nitrify ethers are for example useful in controlled free radical polymerization (CFRP) and by this way incorporated into the polymer in a significant amount, leading in some cases to slightly colored polymers. Controlled free radical polymerization (CFRP) of ethylenically unsaturated monomers has attracted continuing attention, because of its capability to produce polymers with narrow molecular weight distributions and controlled architecture such as block copolymers. US-A-4 581 429 to Solomon et a!., issued April 8,1986, discloses a free radical polymeriza¬tion process which controls the growth of polymer chains to produce short chain or oligo-meric photopolymers and copolymers, including block and graft copolymers. The process employs an initiator having the formula (in part) R'R"N-0-X, where X is a free radical species capable of polymerizing unsaturated monomers. The reactions typically have low conversion rates. Specifically mentioned radical R'R"N-0« groups are derived from 1,1,3,3 tetraethylisoindoline, 1,1,3,3 tetrapropylisoindoline, 2,2,6,6 tetramethylpiperidine, 2,2,5,5 tetramethylpyrrolidine or di-t-butylamine. US 5322912 to Georges et al. issued June 21, 1994 discloses a polymerization process using a free radical initiator, a polymerizable monomer compound and a stable free radical agent of the basic structure R'R"N-0« for the synthesis of photopolymers and block copolymers. WO 98/13392 describes open chain alkoxyamine compounds which have a symmetrical substitution pattern and are derived from NO gas or from nitro so compounds which are suitable regulators for this type of radical polymerization. EP-A-621 878 and EP-A-735 052 disclose a method for preparing thermoplastic polymers of narrow polydispersities by free radical-initiated polymerization, which comprises adding a free radical initiator and a stable free radical agent to the monomer compound. wo 96/24620 describes a polymerization process in which very specific stable free radical agents are used, such as for example bearing a hydrogen atom in a-position to the nitrogen atom. WO 98/30601 discloses specific nitroxyls based on Imldazolidinones, which are also useful for stable free radical mediated polymerization. In addition WO 98/44008 discloses specific nitroxyls based on morpholinones, piperazinones and piperazinediones. All nitroxyl radicals useful in such controlled polymerization processes have inherently a reddish color. Polymers made in the presence of such stable nitroxyl radicals or nitroxyl ethers are end-capped by the nitroxyl group. The bond, polymer to nitroxyl group however is a labile bond, which cleaves upon heating, liberating again the nitroxyl radical and giving thus color to the polymer. The color formation depends, therefore, on the concentration of nitroxyl radical / nitroxylether used to synthesize the polymer. As many processing conditions include a heating step, e. g. removing not reacted monomer, shaping parts by extrusion, injection molding, blow molding and the like, undesirable discoloration accompanies these processes. The problem underlying the present invention is to counteract discoloration resulting from stable free nitroxyl radicals. This problem is solved by adding a reducing agent to the polymer, preferably during a processing step, such as extrusion or injection molding. One subject of the invention is a composition comprising. a) at least one oligomer, cooligomer, polymer or copolymer or blends thereof, containing a stable free nitroxyl radical ; and b) a reducing agent; with the proviso that the composition is essentially free of a polymerizable monomer. Essentially free of a polymerizable monomer means that in some cases there may be a small amount of monomer left from manufacturing the polymer, which could not be completely removed. Preferably no monomer at all is present. Usually the excess monomer is present in an amount of a few ppm. The nitroxyl radical may be present due to its admixture during polymerization, due to its admixture for monomer stabilization, due to its use as chain stopping agent or due to a grafting reaction after polymerization has been completed. The nitroxyl radical may be present as a mixture with the polymer or it may be partially bound to the polymer. The polymers, copolymers, oligomers or cooligomers which can be used in the present invention are listed below. 1. Polymers of monoolefins and diolefins, for example polypropylene, polyisobutylene, po-lybut-1-ene, poly-4-methylpent-1-ene, polyisoprene or polybutadiene, as well as polymers of cycloolefins, for instance of cyclopentene or norbornene, polyethylene (which optionally can be crosslinked), for example high density polyethylene (HOPE), high density and high mole¬cular weight polyethylene (HDPE-HMW), high density and ultrahigh molecular weight poly¬ethylene (HDPE-UHMW), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), (VLDPE) and (ULDPE). Polyolefins, i.e. the polymers of monoolefins exemplified in the preceding paragraph, prefe¬rably polyethylene and polypropylene, can be prepared by different, and especially by the following, methods: a) radical polymerisation (normally under high pressure and at elevated temperature). b) catalytic polymerisation using a catalyst that normally contains one or more than one metal of groups IVb, Vb, VIb or VIII of the Periodic Table. These metals usually have one or more than one ligand, typically oxides, halides, alcoholates, esters, ethers, amines, alkyls, alkenyls and/or aryls that may be either p- or s-coordinated. These metal complexes may be in the free form or fixed on substrates, typically on activated magnesium chloride, titanium(lli) chloride, alumina or silicon oxide. These catalysts may be soluble or Insoluble in the polymerisation medium. The catalysts can be used by themselves in the polymerisation or further activators may be used, typically metal alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyloxanes, said metals being elements of groups la, lla and/or Ilia of the Periodic Table. The activators may be modified conveniently with further ester, ether, amine or silyl ether groups. These catalyst systems are usually termed Phillips, Standard Oil Indiana, Ziegler (-Natta), TNZ (DuPont), metallocene or single site catalysts (SSC). 2. Mixtures of the polymers mentioned under 1), for example mixtures of polypropylene with polyisobutylene, polypropylene with polyethylene (for example PP/HDPE, PP/LDPE) and mixtures of different types of polyethylene (for example LDPE/HDPE). 3. Copolymers of monoolefins and diolefins with each other or with other vinyl monomers, for example ethylene/propylene copolymers, linear low density polyethylene (LLDPE) and mixtures thereof with low density polyethylene (LDPE), propylene/but-1-ene copolymers, propylene/isobutylene copolymers, ethylene/but-1-ene copolymers, ethylene/hexene copo¬lymers, ethylene/methylpentene copolymers, ethylene/heptene copolymers, ethylene/octene copolymers, propylene/butadiene copolymers, isobutylene/isoprene copolymers, ethy-lene/alkyl acrylate copolymers, ethylene/alkyi methacrylate copolymers, ethylene/vinyl ace¬tate copolymers and their copolymers with carbon monoxide or ethylene/acrylic acid copo¬lymers and their salts (ionomers) as well as terpolymers of ethylene with propylene and a diene such as hexadiene, dicyclopentadiene or ethylidene-norbornene; and mixtures of such copolymers with one another and with polymers mentioned in 1) above, for example polypropylene/ethylene-propylene copolymers, LDPE/ethylene-vinyl acetate copolymers (EVA), LDPE/ethylene-acrylic acid copolymers (EAA), LLDPE/EVA, LLDPE/EAA and alter- nating or random polyalkylene/carbon monoxide copolymers and mixtures thereof with other polymers, for example polyamides. 4. Polystyrene, poly(p-methylstyrene), poly(a-methylstyrene). 5. Copolymers of styrene or a-methylstyrene with dienes or acrylic derivatives, for example styrene/butadiene, styrene/acrylonitrile, styrene/alkyi methacrylate, styrene/butadiene/alkyi acrylate, styrene/butadiene/alkyi methacrylate, styrene/maleic anhydride, styrene/acryloni-trile/methyl acrylate; mixtures of high impact strength of styrene copolymers and another polymer, for example a polyacrylate, a diene polymer or an ethylene/propylene/diene terpo-lymer; and block copolymers of styrene such as styrene/butadiene/styrene, styrene/iso-prene/styrene, styrene/ethylene/butylene/styrene or styrene/ethylene/propylene/ styrene. 6. Graft copolymers of styrene or a-methylstyrene, for example styrene on polybutadiene, styrene on polybutadiene-styrene or polybutadiene-acrylonitrile copolymers; styrene and acrylonitrile (or methacrylonitrile) on polybutadiene; styrene, acrylonitrile and methyl meth¬acrylate on polybutadiene; styrene and maleic anhydride on polybutadiene; styrene, acrylo¬nitrile and maleic anhydride or maleimide on polybutadiene; styrene and maleimide on poly¬butadiene; styrene and alkyl acrylates or methacrylates on polybutadiene; styrene and acry¬lonitrile on ethylene/propylene/diene terpolymers; styrene and acrylonitrile on polyalkyi acry¬lates or polyalkyi methacrylates, styrene and acrylonitrile on acrylate/butadiene copolymers, as well as mixtures thereof with the copolymers listed under 6), for example the copolymer mixtures known as ABS, MBS, ASA or AES polymers. 7. Polymers derived from a,p-unsaturated acids and derivatives thereof such as polyacry-lates and polymethacrylates; polymethyl methacrylates, polyacrylamides and polyacryloni-triles, impact-modified with butyl acrylate. 8. Copolymers of the monomers mentioned under 7) with each other or with other unsatu¬rated monomers, for example acrylonitrile/ butadiene copolymers, acrylonitrile/alkyi acrylate copolymers, acrylonitrile/alkoxyalkyi acrylate or acrylonitrile/vinyl halide copolymers or acry¬lonitrile/ alkyl methacrylate/butadiene terpolymers. 9. Polymers derived from unsaturated alcohols and amines or the acyl derivatives or acetals thereof, for example polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl maleate, polyvinyl butyral, polyallyl phthalate or polyallyl melamine; as well as their copolymers with olefins mentioned in 1) above. 10. Homopolymers and copolymers of cyclic ethers such as polyalkylene glycols, polyethy¬lene oxide, polypropylene oxide or copolymers thereof with bisglycidyl ethers. 11. Polyacetals such as polyoxymethylene and those polyoxymethylenes which contain ethylene oxide as a comonomer; polyacetals modified with thermoplastic polyurethanes, acrylates or MBS. 12. Polyphenylene oxides and sulfides, and mixtures of polyphenylene oxides with styrene polymers or polyamides. 13. Polyurethanes derived from hydroxyl-terminated polyethers, polyesters or polybutadi-enes on the one hand and aliphatic or aromatic polyisocyanates on the other, as well as precursors thereof. 14. Polyamides and copolyamides derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, for example polyamide 4, polyamide 6, polyamide 6/6, 6/10, 6/9, 6/12, 4/6, 12/12, polyamide 11, polyamide 12, aromatic polyamides starting from m-xylene diamine and adipic acid; polyamides prepared from hexamethylenediamine and isophthalic or/and terephthalic acid and with or without an ela¬stomer as modifier, for example poly-2,4,4,-trimethylhexamethylene terephthalamide or poly-m-phenylene isophthalamide; and also block copolymers of the aforementioned polyamides with polyolefins, olefin copolymers, ionomers or chemically bonded or grafted elastomers; or with polyethers, e.g. with polyethylene glycol, polypropylene glycol or polytetramethylene glycol; as well as polyamides or copolyamides modified with EPDM or ABS; and polyamides condensed during processing (RIM polyamide systems). 15. Polyureas, polyimides, polyamide-imides, polyetherimids, polyesterimids, polyhydantoins and polybenzimidazoles. 16. Polyesters derived from dicarboxylic acids and diols and/or from hydroxycarboxylic acids or the corresponding lactones, for example polyethylene terephthalate, polybutylene terephthalate, poly-1,4-dimethylolcyciohexane terephthalate and polyhydroxybenzoates, as well as block copolyether esters derived from hydroxyl-terminated polyethers; and also poly¬ esters modified with polycarbonates or MBS. 17. Polycarbonates and polyester carbonates. 18. Polysulfones, polyether sulfones and polyether ketones. 19. Blends of the aforementioned polymers (polyblends), for example PP/EPDM, Poly-amide/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS, PBTP/ABS, PC/ASA, PC/PBT, PVC/CPE, PVC/acrylates, POM/thermoplastic PUR, PC/thermoplastic PUR, POM/acrylate, POM/MBS, PPO/HIPS, PPO/PA 6.6 and copolymers, PA/HDPE, PA/PP, PA/PPO, PBT/PC/ABS or PBT/PET/PC. Preferred is a composition, comprising a) at least one oligomer, cooligomer, polymer or copolymer, obtained by radical polymerization, which polymerization has been carried out in the presence of a stable free nitroxyl radical and a source of free radicals capable of initiating polymerization, or in the presence of a nitroxyl ether wherein X represents a group having at least one carbon atom and is such that the free radical derived from X is capable of initiating polymerization and the remaining radical forms a stable free nitroxyl radical; and b) a reducing agent; with the proviso that the composition is essentially free of a polymerizable monomer. As mentioned before controlled free radical polymerization of ethylenically unsaturated monomers in the presence of nitroxyl radicals or nitroxyl ethers is a known process described in numerous prior art documents. Stable free radicals having a structural element principal known. Suitable compounds and their manufacture are for example described in US 4 581 429, US 5 721 320, US 5627 248, WO 98/13392 , WO98/30601 or in WO 98/44008. Further suitable initiator/regulator compounds and their preparation are described in GB 2 335 190. Another preferred class of initiator/regulator compounds is described in the British patent application GB 2 342 649 . Typically the ethylenically unsaturated monomer or oligomer usefull in controlled polymerization processes is selected from the group consisting of ethylene, propylene, n-butylene, i-butylene, styrene, substituted styrene, conjugated dienes, acrolein, vinyl acetate, vinylpyrrolidone, vinylimidazoie, maleic anhydride, (alkyl)acryiic acidanhydrides, (alkyl)acryiic acid salts, (alkyl)acrylic esters, (meth)acrylonitriles, (alkyl)acrylamides, vinyl halides or vinylidene halides. Preferred ethylenically unsaturated monomers are ethylene, propylene, n-butylene, i-butylene, isoprene, 1,3-butadiene, a-Cs-Cisalkene, styrene, a-methyl styrene, p-methyl styrene or a compound of formula CH2=C(Ra)-(C=Z)-Rb, wherein Ra is hydrogen or Cr C4 alkyl, Rb is NH2, 0'(Me), glycidyl, unsubstituted C1-C18alkoxy, Cj-Ciooalkoxy interrupted by at least one N and/or O atom, or hydroxy-substituted C1-C18alkoxy, unsubstituted d-Ciaalkylamino, di(Ci-Ci8alkyl)amino, hydroxy-substituted Ci-Cisalkylamino or hydroxy-substituted di(Ci-Ci8alkyl)amino, -0-CH2-CH2-N(CH3)2 or -0-CH2-CH2-N'H(CH3)2 An"; An" Is a anion of a monovalent organic or inorganic acid; Me is a monovalent metal atom or the ammonium ion. Z is oxygen or sulfur. Examples of acids from which the anion An" is derived are Ci-Ci2carboxylic acids, organic sulfonic acids such as CF3SO3H or CH3SO3H, mineralic acids such as HCI, HBr or HI, 0x0 acids such as HCIO4 or complex acids such as HPFe or HBF4. Examples for Rg as C2-Ciooalkoxy interrupted by at least one O atom are of formula , wherein Re is Ci-C25alkyl, phenyl or phenyl substituted by Cr C18 alkyl, Rd is hydrogen or methyl and v is a number from 1 to 50. These monomers are for example derived from non ionic surfactants by acrylation of the corresponding alkoxylated alcohols or phenols. The repeating units may be derived from ethylene oxide, propylene oxide or mixtures of both. Further examples of suitable acrylate or methacrylate monomers are given below. An", wherein An" and Ra have the meaning as defined above and Re is methyl or benzyl. An" is preferably CI", Br'or"O3S-CH3. Particularly preferred ethylenically unsaturated monomers are styrene, methylacrylate, ethylacrylate, butylacrylate, isobutylacrylate, tert. butylacrylate, hydroxyethylacrylate, hydroxypropylacrylate, dimethylaminoethylacrylate, glycidylacrylates, methyl(meth)acrylate, ethyi(meth)acrylate, butyl(meth)acry!ate, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, dimethylamlnoethyl(meth)acrylate, glycldyl(meth)acrylates, acrylonltrile, acrylamide, methacrylamide or dimethylamlnopropyl-methacrylamide. The polymerization process may be carried out in the presence of an organic solvent or in the presence of water or in mixtures of organic solvents and water. Additional cosolvents or surfactants, such as glycols or ammonium salts of fatty acids, may be present. Other suitable cosolvents are described hereinafter. If organic solvents are used, suitable solvents or mixtures of solvents are typically pure alkanes (hexane, heptane, octane, isooctane), aromatic hydrocarbons (benzene, toluene, xylene), halogenated hydrocarbons (chlorobenzene), aikanols (methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether), esters (ethyl acetate, propyl, butyl or hexyl acetate) and ethers (diethyl ether, dibutyl ether, ethylene glycol dimethyl ether), or mixtures thereof. The aqueous polymerization reactions can be supplemented with a water-miscible or hydrophilic cosolvent to help ensure that the reaction mixture remains a homogeneous single phase throughout the monomer conversion. Any water-soluble or water-miscible cosolvent may be used, as long as the aqueous solvent medium is effective in providing a solvent system which prevents precipitation or phase separation of the reactants or polymer products until after all polymerization reactions have been completed. Exemplary cosolvents useful in the present invention may be selected from the group consisting of aliphatic alcohols, glycols, ethers, glycol ethers, pyrrolidines, N-alkyI pyrrolidinones, N-alkyI pyrrolidones, polyethylene glycols, polypropylene glycols, amides, carboxylic acids and salts thereof, esters, organosulfides, sulfoxides, sulfones, alcohol derivatives, hydroxyether derivatives such as butyl carbitol or cellosolve, amino alcohols, ketones, and the like, as well as derivatives thereof and mixtures thereof. Specific examples include methanol, ethanol, propanol, dioxane, ethylene glycol, propylene glycol, diethylene glycol, glycerol, dipropylene glycol, tetrahydrofuran, and other water-soluble or water-miscible materials, and mixtures thereof. When mixtures of water and water-soluble or water-miscible organic liquids are selected as the aqueous reaction media, the water to cosolvent weight ratio is typically in the range of about 100:0 to about 10:90. Furthermore CFRP is particularly useful for the preparation of block copolymers. Block copolymers are, for example, block copolymers of polystyrene and polydienes or polyacrylates (e.g., poly(styrene-b-butadiene), poly(styrene-b-isoprene), poly(styrene-£)-acrylate) or poly(styrene-j!)-acrylate-i)-styrene). They are usefull as adhesives or as compatibilizers for polymer blends or as polymer toughening agents. Poly(methylmethacrylate-6-acrylate) diblock copolymers or poly(methylacrylate-6-acrylate-6-methacrylate) triblock copolymers) are useful as dispersing agents for coating systeme, as coating additives (e.g. Theological agents, compatibilizers, reactive diluents) or as resin component in coatings(e.g. high solid paints) Block copolymers of styrene, (meth)acrylates and/or acrylonitrile are useful for plastics, elastomers and adhesives. Block copolymers prepared by CFRP, wherein the blocks alternate between polar monomers and non-polar monomers, are useful in many applications as amphiphilic surfactants or dispersants for preparing highly uniform polymer blends. The (co)polymers may have a number average molecular weight from 1 000 to 400000 g/mol, preferably from 2 000 to 250 000 g/mol and, more preferably, from 2 000 to 200 000 g/mol. The number average molecular weight may be determined by size exclusion chromatography (SEC), matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) or, if the initiator carries a group which can be easily distinguished from the monomer(s), by NMR spectroscopy or other conventional methods. A plurality of specifically designed polymers and copolymers are accessible by this type of controlled radical polymerization, such as star and graft (co)polymers as described, inter alia, by C. J. Hawker in Angew. Chemie, 1995, 107, pages 1623-1627, dendrimers as described by K. Matyaszewski et al. in Macromolecules 1996, Vol 29, No. 12, pages 4167-4171, graft (co)polymers as described by C. J. Hawker et al. in Macromol. Chem. Phys. 198, 155-166(1997), random copolymers as described by C. J. Hawker in Macromolecules 1996, 29, 2686-2688, or diblock and triblock copolymers as described by N. A. Listigovers in Macromolecules 1996, 29, 8992-8993. Preferably the reducing agent is a cyclic ethylenically unsaturated compound having an aliylic hydrogen atom, a phosphorous compound with oxidation number l-IV and a valence of 3 to 5 or a sulfur compound with oxidation number l-IV and a valence of 2 or 4 or a mixture thereof. Particularly preferred is a composition, wherein the reducing agent is a mixture of a cyclic ethylenically unsaturated compound having an allylic hydrogen atom and a phosphorous compound with oxidation number l-IV and a valence of 3 to 5 or a sulfur compound with oxidation number l-IV and a valence of 2 to 4. Suitable organic phosphorous compounds are R'-H2P02, R'R"HPO or R'R"HP03, P(0R)3 wherein R' and R" independently are C1 - C18 AralkyI, phenyl or C1-C18alkyl. Also suitable organic phosphites and phosphonites are for example triphenyl phosphite, diphenyl alkyl phosphites, phenyl dialkyi phosphites, tris(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)-pentaerythritol diphosphite, diisodecyloxypentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl)pentaerythritol diphosphite, bis(2,4,6-tris(tert-butyiphenyl)pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakls(2,4-di-tert-butylphenyl) 4,4'-biphenylene diphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenz[d,g]-1,3,2-dioxaphosphocin, 6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenz[d,g]-1,3,2-dioxaphosphocin, bis(2,4-di-tert-butyl-6-methylphenyl) methyl phosphite, bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite, 2,2',2"-nitrilo-[triethyltris(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl)phosphite], 2-ethylhexyl(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl)phosphite. Especially preferred are the following phosphites: Particularly preferred sulfur compounds are: H2S2O2/H2S2O3 sulfoxylic-/ thlosulfuric acid H2S2O4 dithionic acid H2SO3/H2S2O5 sulfurous-Zdisulfurous acid R-S-OH sulfenic acid R-S=0-OH sulfinic acid and their amonium, alkali or alkali earth salts. The salts may also contain crystal water. Typically the alkali or alkali earth metal is Li, Na, K, Ca, Mg. The salts can contain additional crystal water. Most preferred are H3PO2 (phosphinic acid), or a Na, K, Ca, Mg or ammonium salt thereof, with or without crystal water. Particularly preferred is NaH2P02 which may contain additional crystal water. Examples of cyclic ethylenically unsaturated compounds are dihydroanthacene and dihydronaphtaline and their derivatives, wherein RrRe independently are H, alkyl, cycloalkyi, aryl, aralkyi, alkenyl, alkinyl or COOalkyl. The aromatic radicals may also be further substituted. The substituents R29-R50 have the same meaning as given for Ri-Re and L2 is a number from 1-100. Preferably the meaning of R1-R50 is hydrogen or Ci-C4a!kyl. Preferably the reducing agent is a cyclic mono-, sesqui- or di-terpene having an allylic hydrogen atom. Examples are a-terpinene, y-terpinene, a-phellandrene, p-phellandrene, limonene, a-pinene, p-pinene, a-terpineol, cadinene, p-selinene, p-lonone, abietic acid. Most preferred are y-terpinene and a-phellandrene. The reducing agent is preferably present in an amount of from 0.01% to 5%, more preferably from of from 0.05% to 3%, based on the weight of the polymer. The concentration to be used depends on the amount of nitroxyl present in the oligomer or polymer. Obviously for high concentrations of nitroxyl, high concentrations of the reducing agent are used. Furthermore it depends on the color improvement (color stability of the polymer) to be targeted If a mixture of a cyclic ethylenically unsaturated compound having an allylic hydrogen atom (a) and a phosphorous compound with oxidation number l-IV and a valence of 3 to 5 (b) is used, the ratio (a):(b) may vary from 1:10 to 10:1, preferably it is from 1:5 to 5:1 and most preferably from 1:2 to 2:1. The composition can also contain further additives. Examples are given below. 1. Antioxidants 1.1. Alkylated monophenols. for example 2,6-di-tert-buty!-4-methylphenol, 2-tert-butyl-4,6-di-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-bu-tyl-4-isobutyiphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(a-methylcyclohexyl)-4,6-dimethyl-phenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-trJcyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, nonylphenols which are linear or branched in the side chains, for example, 2,6-di-nonyl-4-methylphenol, 2,4-dimethyl-6-(1'-methylundec-1'-yl)phenol, 2,4-di-methyl-6-(1 '-methylheptadec-1 '-yl)phenol, 2,4-dimethyl-6-(1 '-methyltridec-1 '-yl)phenol and mixtures thereof. 1.2. Alkylthiomethylphenols. for example 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,4-dioc-tylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-di-dodecylthiomethyl-4-nonylphenol. 1.3. Hydroquinones and alkylated hydroquinones. for example 2,6-di-tert-butyl-4-methoxy-phenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octade-cyloxyphenol, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl stearate, bis-(3,5-di-tert-butyl-4-hydroxyphenyl) adipate. 1.4. Tocopherols, for example a-tocopherol, b-tocopherol, g-tocopherol, d-tocopheroi and mixtures thereof (Vitamin E). 1.5. Hydroxylated thiodiphenvl ethers, for example 2,2'-thiobis(6-tert-butyl-4-methylphenol), 2,2'-thiobis(4-octylphenol), 4,4'-thiobis(6-tert-butyl-3-methylphenol), 4,4'-thiobis(6-tert-butyl-2-methylphenol), 4,4'-thiobis-(3,6-di-sec-amylphenol), 4,4'-bis(2,6-dimethyl-4-hydroxyphe-nyl)disulfide. 1.6. Alkylidenebisphenols. for example 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), 2,2'-methylenebis[4-methyl-6-(a-methylcyclohexyl)-phenol], 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis(6-nonyl-4-me-thylphenol), 2,2'-methylenebis(4,6-di-tert-butylphenol), 2,2'-ethylidenebis(4,6-di-tert-butyl- phenol), 2,2'-ethylidenebis(6-tert-butyl-4-isobutylphenol), 2,2'-methylenebis[6-(a-methylben-zyl)-4-nonylphenol], 2,2'-methylenebis[6-(a,a-dimethylbenzyl)-4-nonylphenol], 4,4'-methy-lenebis(2,6-di-tert-butylphenol), 4,4'-methylenebis(6-tert-butyl-2-methylphenol), 1,1-bis(5-tert-buty!-4-hydroxy-2-methylpheny()butane, 2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 1,1 -bis(5-tert-butyl-4-hydroxy-2-methyl-phenyl)-3-n-dodecylmercaptobutane, ethylene glycol bls[3,3-bis(3'-tert-butyl-4'-hydroxyphenyl)butyrate], bis(3-tert-butyl-4-hydroxy-5-methyl-phenyl)dicyclopentadi-ene, bis[2-(3'-tert-butyl-2'-hydroxy-5'-methylbenzyl)-6-tert-butyl-4-methylphenyl]terephthalate, 1,1-bis-(3,5-dimethyl-2-hydroxyphenyl)butane, 2,2-bls-(3,5-dl-tert-butyl-4-hydroxyphe-nyl)propane, 2,2-bis-(5-tert-butyl-4-hydroxy2-methylphenyl)-4-n-dodecylmercaptobutane, 1,1,5,5-tetra-(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane. 1.7. 0-. N- and S-benzvl compounds, for example 3,5,3',5'-tetra-tert-butyl-4,4'-dlhydroxydi-benzyl ether, octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate, tridecyl-4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)amine, bjs(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dlthioterephthalate, bis(3,5-di-tert-butyl-4-hydroxy-benzyl)sulfide, isooctyl-3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate. 1.8. Hydroxybenzvlated maionates, for example dioctadecyl-2,2-bis-(3,5-di-tert-butyl-2-hy-droxybenzyl)-malonate, dl-octadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)-malonate, di-dodecylmercaptoethyl-2,2-bls-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, bls[4-(1,1,3,3-te-tramethylbutyl)phenyl]-2,2-bls(3,5-dJ-tert-butyl-4-hydroxybenzyl)malonate. 1.9. Aromatic hydroxybenzyl compounds, for example 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxy-benzyl)-2,4,6-trimethylbenzene, 1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetrame-thylbenzene, 2,4,6-tris(3,5-dl-tert-butyl-4-hydroxybenzyl)phenol. 1.10. Triazine Compounds, for example 2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl-4-hy- droxyanillno)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanillno)-1,3,5- triazlne, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine, 2,4,6- tris(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,2,3-triazine, 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxy- benzyl)isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dlmethylbenzyl)isocyanurate, 2,4,6- tris(3,5-dl-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine, 1,3,5-tris(3,5-di-tert-butyl-4- hydroxyphenylpropionyl)-hexahydro-1,3,5-triazine, 1,3,5-tris(3,5-dicyclohexyl-4-hydroxyben-zyl)isocyanurate. 1.11. Benzylphosphonates, for example dimethyl-2,5-di-tert-butyl-4-hydroxybenzylphospho-nate, diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl3,5-di-tert-butyl-4-hy-droxybenzylphosphonate, dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, the calcium salt of the monoethyl ester of 3,5-dl-tert-butyl-4-hydroxybenzylphosphonic acid. 1.12. Acvlaminophenols. for example 4-hydroxylauranilide, 4-hydroxystearanilide, octyl N-(3,5-di-tert-butyl-4-hydroxyphenyl)carbamate. 1.13. Esters of b-(3.5-di-tert-butvl-4-hvdroxvphenvl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethy-lene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N'-bis(hy-droxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylol-propane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane. 1.14. Esters of b-(5-tert-butvl-4-hvdroxv-3-methvlphenvl)propionic acid with mono- or poly¬hydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexane¬diol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N'-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane. 1.15. Esters of b-(3.5-dicvclohexvl-4-hvdroxvphenvl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N'-bis(hydroxyethyl)ox-amide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hy-droxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane. 1.16. Esters of 3,5-di-tert-butvl-4-hvdroxvphenvl acetic acid with mono- or polyhydric alco¬hols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythrltol, tris(hydroxyethyl)isocyanurate, N,N'-bis(hydroxyethyl)ox-amide, 3-thlaundecanol, 3-thlapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hy-droxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane. 1.17. Amides of b-(3,5-di-tert-butvl-4-hvdroxvphenvl)proplonic acid e.g. N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylproplonyl)hexamethylenediamide, N,N'-bls(3,5-dl-tert-butyl-4-hydroxy-phenylpropionyl)trimethylenediamlde, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)-hydrazide, N,N'-bis[2-(3-[3,5-di-tert-butyl-4-hydroxypheny!]propionyloxy)ethyl]oxamide (Naugard®XL-1 supplied by Unlroyal). 1.18. Ascorbic acid (vitamin C) 1.19. Aminic antioxidants, for example N,N'-di-isopropyl-p-phenylenediamine, N,N'-di-sec-butyl-p-plnenylenediamine, N,N'-bis(1,4-dimetliylpentyl)-p-phenylenediamine, N,N'-bis(1-etliyl-3-methylpenty!)-p-phenylenediamine, N,N'-bis(1-metliylheptyl)-p-phenylenediamine, N,N'-dicyclolnexyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-bis(2-naph-tiiyl)-p-phenylenediamine, N-isopropyl-N'-piienyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-{1 -methylheptyl)-N'-plienyl-p-phenylenediamine, N-cyclo-hexyl-N'-phenyl-p-phenlenediamine, 4-(p-toluenesulfamoyl)diphenylamine, N,N'-dimethyl-N,N'-di-sec-butyl-p-plienylenediamine, diphenylamine, N-allyldiphenylamine, 4-isopropoxy-diphenylamine, N-ptienyl-1-naphtliylamine, N-(4-tert-octylphenyl)-1-naphthylamine, N-phe-nyi-2-naphthylamine, octylated diphenylamine, for example p,p'-di-tert-octyldiphenylamine, 4-n-butylaminophenol, 4-butyrylaminophenol, 4-nonanoylaminophenol, 4-dodecanoylamino-phenol, 4-octadecanoylaminophenol, bis(4-methoxyphenyl)amine, 2,6-di-tert-butyl-4-dime-thylaminomethylphenol, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, N,N,N',N'-tetramethyl-4,4'-diaminodiphenylmethane, 1,2-bis[(2-methylphenyl)amino]ethane, 1,2-bis(phenylamino)propane, (o-tolyl)biguanide, bis[4-(r,3'-dimethylbutyl)phenyl]amine, tert-octylated N-phenyl-1-naphthylamine, a mixture of mono- and dialkylated tert-butyl/tert-octyldiphenylamines, a mixture of mono- and dialkylated nonyldiphenylamines, a mixture of mono- and dialkylated dodecyldiphenylamines, a mixture of mono- and dialkylated isopro-pyl/isohexyldiphenylamines, a mixture of mono- und dialkylated tert-butyidiphenylamines, 2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, a mixture of mono- und dial¬kylated tert-butyl/tert-octylphenothiazines, a mixture of mono- und dialkylated tert-octyl-phe- nothiazines, N-allylphenothiazin, N,N,N',N'-tetraphenyl-1,4-diaminobut-2-ene, N,N-bis-(2,2,6,6-tetramethyl-piperid-4-yl-hexamethylenediamine, bis(2,2,6,6-tetrannethylpiperid-4-yl)-sebacate, 2,2,6,6-tetramethylpiperidin-4-one, 2,2,6,6-tetramethylpiperidin-4-ol. 2. UV absorbers and light stabilisers 2.1 ■ 2-(2'-HvdroxvDhenvi)benzotriazoles. for example 2-(2'-hydroxy-5'-methylphenyl)-ben2o-triazole, 2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(5'-tert-butyl-2'-hydroxyphe-nyl)benzotriazole, 2-(2'-hydroxy-5'-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole, 2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-methylphe-nyl)-5-chloro-benzotriazole, 2-(3'-sec-butyl-5'-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-4'-octyloxyphenyl)benzotriazole, 2-(3',5'-di-tert-amyl-2'-hydroxyphenyl)benzotriazole, 2-(3',5'-bis-(a,a-dimethylbenzyl)-2'-hydroxyphenyl)benzotria2ole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-{3'-tert-butyl-5'-[2-(2-ethylhexyloxy)-carbonylethyl]-2'-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-2'-hy-droxy-5'-(2-methoxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-methoxycarbonylethyl)phenyl)benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-octyloxy-carbonylethyl)phenyl)benzotriazole, 2-(3'-tert-butyl-5'-[2-(2-ethylh6xyloxy)carbonylethyl]-2'-hydroxyphenyl)benzotriazole, 2-(3'-dodecyl-2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-isooctyIoxycarbonylethyl)phenylbenzotriazole, 2,2'-methylene-bis-[4-(1,1,3,3-tetramethylbutyl)-6-benzotriazole-2-ylphenol]; the transesterification product of 2-[3'-tert-butyl-5'-(2-methoxycarbonylethyl)-2'-hydroxyphenyl]-2H-benzotriazole with polyethy¬lene glycol 300; [R-CHJCHJ-COO-CHJCHJ-^ where R = 3'-tert-butyl-4'-hydroxy-5'-2H- benzotriazol-2-ylphenyl, 2-[2'-hydroxy-3'-(a,a-dimethylbenzyl)-5'-(1,1,3,3-tetramethylbutyl)-phenyl]benzotriazole; 2-[2'-hydroxy-3'-(1,1,3,3-tetramethylbutyl)-5'-(a,a-dimethylbenzyl)-phenyl]benzotriazole. 2.2. 2-Hvdroxvbenzophenones. for example the 4-hydroxy, 4-methoxy, 4-octyloxy, 4-decyl-oxy, 4-dodecyloxy, 4-benzyloxy, 4,2',4'-trihydroxy and 2'-hydroxy-4,4'-dimethoxy derivatives. 2.3. Esters of substituted and unsubstituted benzoic acids, as for example 4-tertbutyl-phenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoyi resorcinol, bis(4-tert-butylben-zoyl) resorcinol, benzoyl resorcinol, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzo- ate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl 3,5-di-tert-butyl-4-hydroxy-benzoate, 2-methyl-4,6-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate. 2.4. Acrylates. for example ethyl a-cyano-b,b-diphenylacrylate, isooctyl a-cyano-b,b-diphe-nylacrylate, methyl a-carbomethoxycinnamate, methyl a-cyano-b-methyl-p-methoxy-clnna-mate, butyl a-cyano-b-methyl-p-methoxy-cinnamate, methyl a-carbomethoxy-p-methoxycln-namate and N-(b-carbomethoxy-b-cyanovlnyl)-2-methyllndoline. 2.5. Nickel compounds, for example nickel complexes of 2,2'-thio-bis-[4-(1,1,3,3-tetrame-thylbutyl)phenol], such as the 1:1 or 1:2 complex, with or without additional ligands such as n-butylamine, triethanolamine or N-cyclohexyldiethanolamine, nickel dibutyldithiocarbamate, nickel salts of the monoalkyi esters, e.g. the methyl or ethyl ester, of 4-hydroxy-3,5-di-tert-butylbenzylphosphonic acid, nickel complexes of ketoximes, e.g. of 2-hydroxy-4-methylphe-nyl undecylketoxime, nickel complexes of 1-phenyl-4-lauroyl-5-hydroxypyrazole, with or without additional ligands. 2.6. Stericallv hindered amines, for example bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl)succinate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(1 -octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-pi-peridyl) n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensate of 1-(2-hydroxy-ethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, linear or cyclic condensates of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-tert-octylamino-2,6-dichloro-1,3,5-triazine, tris(2,2,6,6-tetramethyl-4-piperidyl)nitrilotriacetate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate, 1,1'-(1>2-ethanediyl)-bis(3,3,5,5-tetramethylpiperazinone), 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate, 3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decan-2,4-dione, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)sebacate, bis(1-octyloxy-2,2,6,6-tetrame-thylpiperidyl)succinate, linear or cyclic condensates of N,N'-bis-(2,2,6,6-tetramethyl-4-piperi-dyl)hexamethylenediamine and 4-morpholino-2,6-dichloro-1,3,5-triazine, the condensate of 2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl )-1,3,5-triazine and 1,2-bis(3-aminopropylamino)ethane, the condensate of 2-chloro-4,6-di-(4-n-butylamino-1,2,2,6,6-pen-tamethylpiperidyl)-1,3,5-triazine and 1,2-bis-(3-aminopropylamino)ethane, 8-acetyl-3-dode-cyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione, 3-dodecyl-1-(2,2,6,6-tetrame- thyl-4-piperidyl)pyrrolidin-2,5-dione, 3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrroli-dine-2,5-dione, a mixture of 4-hexadecyloxy- and 4-stearyloxy-2,2,6,6-tetramethylpiperidine, a condensation product of N,N'-bis(2,2,6,6-tetrametiiyl-4-piperidyl)hexamethylenediamine and 4-cyclohexylamino-2,6-dichloro-1,3,5-triazine, a condensation product of 1,2-bis(3-ami-nopropylamino)etiiane and 2,4,6-trichloro-1,3,5-triazine as well as 4-butylamino-2,2,6,6-te-tramethylpiperidine (CAS Reg. No. [136504-96-6]); N-(2,2,6,6-tetramethyl-4-piperidyl)-n-do-decylsuccinimid, N-(1,2,2,6,6-pentamethyl-4-piperidyi)-n-dodecylsuccinimid, 2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4,5]decane, a reaction product of 7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro [4,5]decane und epichlorohydrin, 1,1-bis(1,2,2,6,6-pentannethyl-4-piperidyloxycarbonyl)-2-(4-metiioxyphenyl)ethene, N,N'-bis-formyl-N,N'-bis(2,2,6,6-tetrametlnyl-4-piperidyl)hexamethylenediamine, diester of 4-methoxy-metliyiene-malonic acid with 1,2,2,6,6-pentamethyi-4-hydroxypiperidine, poly[methylpropyl-3-oxy-4-(2,2,6,6-tetrametiiyl-4-piperidyi)]siloxane, reaction product of maleic acid anhydride-a-olefin-copoiymer with 2,2,6,6-tetramethyl-4-aminopiperidine or 1,2,2,6,6-pentamethyl-4-aminopiperidine. 2.7. Oxamides, for example 4,4'-dioctyloxyoxanilide, 2,2'-diethoxyoxanilide, 2,2'-dioctyloxy-5,5'-di-tert-butoxanilide, 2,2'-didodecyloxy-5,5'-di-tert-butoxanilide, 2-ethoxy-2'-ethyloxanilide, N,N'-bis(3-dimethylaminopropyl)oxamide, 2-ethoxy-5-tert-butyi-2'-ethoxanilide and its mixture with 2-ethoxy-2'-ethyl-5,4'-di-tert-butoxanilide, mixtures of o- and p-methoxy-disubstituted oxanllides and mixtures of o- and p-ethoxy-disubstituted oxaniiides. 2.8. 2-(2-Hvdroxvphenvi)-1.3.5-triazines, for example 2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxypheny!)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-pro-pyloxyphenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis-(4-methylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-bis(2,4-dimethylphe-nyl)-1,3,5-triazine, 2-(2-hydroxy-4-tridecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-tri-azine, 2-[2-hydroxy-4-(2-hydroxy-3-butyloxy-propoxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3,5-tri¬azine, 2-[2-hydroxy-4-(2-hydroxy-3-octyloxy-propyloxy)phenyl]-4,6-bls(2,4-dimethyl)-1,3,5-triazine, 2-[4-(dodecyloxy/tridecyloxy-2-hydroxypropoxy)-2-hydroxy-phenyl]-4,6-bis(2,4-di-methylphenyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-dodecyloxy-propoxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-hexyloxy)phenyl-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4,6-tris[2-hydroxy-4-(3- butoxy-2-hydroxy-propoxy)phenyl]-1,3,5-tria2ine, 2-(2-hydroxyphenyl)-4-(4-methoxyphenyl)-6-phenyl-1,3,5-triazine, 2-{2-hydroxy-4-[3-(2-ethylhexyl-1-oxy)-2-hydroxypropyloxy]phenyl}-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine. 3. Metal deactivators, for example N,N'-dlphenyloxamide, N-sallcylal-N'-salicyloyI hydrazine, N,N'-bis(salicyloyl) hydrazine, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hydrazine, 3-salicyloylamino-1,2,4-triazole, bis(benzylidene)oxalyl dihydrazide, oxanilide, isophthaloyi dihydrazide, sebacoyi bisphenylhydrazide, N,N'-diacetyladipoyl dihydrazide, N,N'-bis(salicyl-oyl)oxalyl dihydrazide, N,N'-bis(salicyloyl)thiopropionyl dihydrazide. 4. Hvdroxvlamines. for example, N,N-dibenzylhydroxylamine, N,N-diethylhydroxylamine, N,N-dioctylhydroxylamine, N,N-dilaurylhydroxylamine, N,N-ditetradecylhydroxylamine, N,N-dihexadecylhydroxylamine, N,N-dioctadecylhydroxylamine, N-hexadecyl-N-octadecylhy-droxylamine, N-heptadecyl-N-octadecylhydroxylamine, N,N-dialkylhydroxylamine derived from hydrogenated tallow amine. 5. Nitrones, for example, N-benzyl-alpha-phenyl-nitrone, N-ethyl-alpha-methyl-nitrone, N-oc-tyl-alpha-heptyl-nitrone, N-lauryl-alpha-undecyl-nitrone, N-tetradecyl-alpha-tridcyl-nitrone, N-hexadecyl-alpha-pentadecyl-nitrone, N-octadecyl-alpha-heptadecyl-nitrone, N-hexadecyl-alpha-heptadecyl-nitrone, N-ocatadecyl-alpha-pentadecyl-nitrone, N-heptadecyl-alpha-hep-tadecyl-nitrone, N-octadecyl-alpha-hexadecyl-nitrone, nitrone derived from N,N-dialkylhy-droxylamine derived from hydrogenated tallow amine. 6. Thiosynergists, for example, dilauryl thiodipropionate or distearyl thiodipropionate. 7. Basic co-stabilisers, for example, melamine, polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, urea derivatives, hydrazine derivatives, amines, polyamides, polyurethanes, alkali metal salts and alkaline earth metal salts of higher fatty acids for example calcium stearate, zinc stearate, magnesium behenate, magnesium stearate, sodium ricinoleate and potassium palmitate, antimony pyrocatecholate or zink pyrocatecholate. 8. Nucleating agents, for example, inorganic substances such as talcum, metal oxides such as titanium dioxide or magnesium oxide, phosphates, carbonates or sulfates of, preferably, alkaline earth metals; organic compounds such as mono- or polycarboxylic acids and the salts thereof, e.g. 4-tert-butylbenzoic acid, adipic acid, diphenylacetic acid, sodium succinate or sodium benzoate; polymeric compounds such as ionic copolymers (ionomers). 9. Fillers and reinforcing agents, for example, calcium carbonate, silicates, glass fibres, glass bulbs, asbestos, talc, kaolin, mica, barium sulfate, metal oxides and hydroxides, car¬ bon black, graphite, wood flour and flours or fibers of other natural products, synthetic fibers. 10. Other additives, for example, plasticisers, lubricants, emulsifiers, pigments, rheology additives, catalysts, flow-control agents, optical brighteners, flameproofing agents, antistatic agents and blowing agents. 11. Benzofuranones and Indolinones, for example those disclosed In U.S. 4,325,863; U.S. 4,338,244; U.S. 5,175,312; U.S. 5,216,052; U.S. 5,252,643; DE-A-4316611; DE-A-4316622; DE-A-4316876; EP-A-0589839 or EP-A-0591102 or 3-[4-(2-acetoxyethoxy)-phenyl]-5,7-di-tert-butyl-benzofuran-2-one, 5,7-dl-tert-butyl-3-[4-(2-stearoyloxyethoxy)phe-nyl]benzofuran-2-one, 3,3'-bis[5,7-dl-tert-butyl-3-(4-[2-hydroxyethoxy]phenyl)benzofuran-2-one], 5,7-dl-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one, 3-(4-acetoxy-3,5-dimethylphe-nyl)-5,7-dl-tert-butyl-benzofuran-2-one, 3-(3,5-dimethyl-4-plvaloyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one, 3-(3,4-dimethylphenyl)-5,7-dl-tert-butyl-benzofuran-2-one, 3-(2,3-di-methylphenyl)-5,7-di-tert-butyl-benzofuran-2-one. Another subject of the Invention is a process for improving the color of an oligomer, cooligomer, polymer or copolymer or blends thereof, containing a stable free nitroxyl radical by adding a reducing agent to said polymer and heating said mixture to above the glass temperature in case of amorphous polymers or above the melting point in case of crystalline or semi-crystalline polymers; with the proviso that essentially no polymerizable monomer Is present. There are different reasons, why stable free nitroxyl radicals may be present in a polymer One possibility Is that graft polymers have been prepared in the presence of a nitroxyl radical or a nitroxyl ether. Such a process typically comprises a first step A), wherein a stable nitroxyl radical is grafted onto a polymer, which step comprises heating a polymer and a compound containing a stable NO radical to above the melting point of the polymer, mixing and reacting the components at said temperature; and in a second step B) the grafted polymer of step A) is heated in the presence of an ethylenically unsaturated monomer or oligomer to a temperature at which cleavage of the nitroxyl-polymer bond occurs. Such polymers, grafted in the presence of a nitroxyl radical or a nitroxyl ether are also a preferred embodiment of the present invention. The stable free nitroxyl radical may also be present in the polymer due to its admixture for monomer stabilization or due to its use as chain stopping agent. Preferred is a process for improving the color of polymers, obtained by radical polymerization, which polymerization has been carried out in the presence of a stable free nitroxyl radical and a source of free radicals capable of initiating the polymerization, or in the presence of a nitroxyl ether , wherein X represents a group having at least one carbon atom and is such that the free radical derived from X is capable of initiating polymerization and the remaining radical forms a stable free nitroxyl radical; by adding a reducing agent to said polymer and heating said mixture to above the glass temperature In case of amorphous polymers or above the melting point in case of crystalline or semi-crystalline polymers; with the proviso that essentially no polymerizable monomer is present. The process is preferably carried out, wherein the mixture is heated to 50°-150° C above the glass temperature in case of amorphous polymers or 20°-180° C above the melting point in case of crystalline or semi-crystalline polymers. The heating step of the process may be performed in any reactor suitable for mixing a polymer melt. Preferably the reactor is an extruder or kneading apparatus as for example described in "Handbuch der Kunststoffextrusion" Vol.1, editor F. Hensen, W. Knappe and H. Potente, 1989, pages 3-7. If an extruder is used the process may be described as reactive extrusion process. Examples of reactiv extrusion equipment and processes are given by G. H. Hu et a!., in "Reactive Modifiers for Polymers", first edition, Blackie Academic & Professional an Imprint of Chapman & Hall, London 1997, chapter 1, pages 1-97. Preferably, If an extruder is used, a reduced pressure of less than 200 mbar is applied during extrusion. Volatile by products may be removed thereby. Typical reaction times are from a few seconds to several hours. Preferably the reaction time is from 10 seconds to 1 h, most preferably from 20 seconds to 20 min. Another subject is the use of a reducing agent for improving the color of an oligomer, cooligomer, polymer or copolymer or blends thereof, containing a stable free nitroxyl radical \ N-0- . / Still another subject of the invention is the use of a reducing agent for removing the discoloration of polymers, obtained by radical polymerization, which polymerization has been carried out in the presence of a stable free nitroxyl radical and a source of free radicals capable of initiating the polymerization, or in the presence of a nitroxyl ether , wherein X represents a group having at least one carbon atom and is such that the free radical derived from X is capable of initiating polymerization and the remaining radical forms a stable free nitroxyl radical. The following examples illustrate the invention. The nitroxyl compounds A, B and C used in the following examples are known and can be prepared by oxidation of the corresponding amines for example according to US 5,654,434, 5,204,473 and GB 2 335 190. Example 1 Color improvement of polystyrene synthesized by controlled free radical polymerization in presence of a nitroxyl radical In a 2 I reactor 1.419 g (5.858 mmol) dibenzoyi peroxide and 2.707 g (7.615 mmol) dodecanoic acid-(2,2,6,6-tetramethyl-piperidine-4-yl-1-oxyl)ester (nitroxyl A) are added to 1590 g (15.27 mol) styrene under argon atmosphere. Dissolved oxygen is removed in re¬peating evacuation/Ar-purging steps. The reaction mixture is stirred and heated under argon atmosphere to 125° C for 6 hours. Remaining monomer is removed at 60° C under vacuum. The residue is dried in a first step under vacuum and in a second step under normal pressure at 70° C until constant weight is achieved (1390 g polystyrene, 87 % conversion). From the synthesized polystyrene a molded plaque of 2 mm thickness is prepared (molding conditions: 1 min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The yellowness index is measured according to DIN 53383. In a twin screw extruder, model TW 100, Haake, the synthesized polystyrene is extruded together with the additives given in table 3 at a temperature T^ax - 220 °C (heating zones 1 - 5) and 40 r/min. The product is granulated from strands in a water bath. From the granules a molded plaque of 2 mm thickness is prepared (molding conditions: 1 min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The plaques are stored at 80° C in a circulating air drying oven in order to determine discoloration during thermal aging after definite time intervals. Table 1 shows the measured yellowness index at different time intervals (h). Example 2-4 Color Improvement of polystyrene containing nitroxyl-radicals (model experiment) In a twin screw extruder, model TW 100, Haake, a commercial general purpose polystyrene (PS-165/H ex BASF, MFR(200/5) - 2-9) is extruded together with 0.1% decandioic acid bis(2,2,6,6-tetramethyl-piperidine-4-yl-1-oxyl)ester (CXA 5415, commercial nitroxyl of Ciba Specialty Chemicals) at a temperature Tmax = 220 °C (heating zones 1 - 5) and 40 r/min. The product is granulated from strands in a water bath. From the granules a molded plaque of 2 mm thickness is prepared (molding conditions: 1 min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The yellowness index is measured according to DIN 53383. The nitroxyl radical containing granulate is extruded for a second time together with the additives given in table 1 (Tmax =250 °C (heating zone 1 - 5) and 40 r/min), granules are formed and molded plaques are prepared as given above. The plaques are stored at 80° C in a circulating air drying oven in order to determine discoloration during thermal aging after definite time intervals. Table 2 shows the measured yellowness index at different time intervals (h). In a twin screw extruder, model ZSK 25, Werner & Pfleiderer, a commercial grade low density polyethylene (Lupolen 1812E ex BASF, MFR(190/21.6) = 34) is extruded together with 0.1% dodecanoic acid(2,2,6,6-tetramethyl-piperidine-4-yl-1-oxyl)ester at a temperature Tmax ~ 200 °C (heating zones 1 - 5) and 100 r/min. The product is granulated from strands in a water bath. From the granules a molded plaque of 2 mm thickness is prepared (molding conditions: 1 min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The yellowness index is measured according to DIN 53383. The nitroxyl radical containing granulate is extruded for a second time together with the additives given in table 1 (Tmax = 220 °C (heating zone 1 - 5) and 100 r/min), granules are formed and molded plaques are prepared as given above. Table 3 shows the measured yellowness index. Table 3: yellowness index of molded polyethylene Example 9-13 Color improvement of polystyrene containing nitroxyl-radicals (model experiment) In a twin screw extruder, model ZSK 25, Werner & Pfleiderer, a commercial general purpose polystyrene (PS-165/H ex BASF, MFR(200/5) = 2.9) is extruded together with 0.05% octadecanoic acid(2,2,6,6-tetramethyl-piperidine-4-yl-1-oxyl)ester at a temperature Tmax -220 "C (heating zones 1-5) and 100 r/min. The product is granulated from strands in a water bath. From the granules a molded plaque of 2 mm thickness is prepared (molding conditions: 1 min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The yellowness index is measured on a Minolta CM 3600D according to DIN 6167. The nitroxyl radical containing granulate is extruded for a second time together with the additives given in Table 4 (Tmmx = 220 "C (heating zone 1 - 5) and 100 r/min), granules are formed and molded plaques are prepared as given above. Table 4 shows the measured yellowness index. Table 4: yellowness index of molded polystyrene Example 14-20 Color improvement of polystyrene containing nitroxyl-radicals (model experiment) In a twin screw extruder, model ZSK 25, Werner & Pfleiderer, a commercial general purpose polystyrene (PS-165/H ex BASF, MFR(200/5) = 3.5) is extruded together with 0.05% acetic acid(2,6-diethyl-2,3,6-trimethyl-piperidine-4-yl-1-oxyl)ester at a temperature Tmax = 220 °C (heating zones 1 - 5) and 100 r/min. The product is granulated from strands in a water bath. From the granules a molded plaque of 2 mm thickness is prepared (molding conditions: 1 min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The yellowness index is measured on a Minolta CM 3600D according to DIN 6167. The nitroxyl radical containing granulate is extruded for a second time together with the additives given in table 4 (Tmax = 220 X (heating zone 1 - 5) and 100 r/min), granules are formed and molded plaques are prepared as given above. Table 5 shows the measured yellowness index. Irgafos P-EPQ = tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]4,4'-diylbisphosphonite (commercial product of Ciba Specialty Chemicals) Irgafos TNPP =tns(nonyl-phenyl)phosphite (commercial product of Ciba Specialty Chemicals) Irgafos 126 = bis(2,4-di-tert-butylphenyl)pentaerythrol-diphosphite (commercial product of Ciba Specialty Chemicals) WE CLAIM: 1. A composition for improving the colour of polymers comprising, a) at least one oligomer, cooligomer, polymer or copolymer or blends thereof, obtainable by radical polymerization or by grafting, which polymerization or grafting has been carried out in the presence of a stable free nitroxyl radical and a source of free radicals capable of initiating the polymerization, or in the presence of a. nitroxyl ether wherein X represents a group having at least one carbon atom and is such that the free radical derived from X is capable of initiating polymerization and the remaining radical forms a stable free nifroxyl radical; and b) a reducing agent, which is selected from the group consisting of a cyclic ethylenically unsaturated compound having an allylic hydrogen atom, H3PO2 (phosphinic acid), H4P2O4 (hypodiphosphonic acid), H5PO3/H4P2O5 (phosphonic-/diphosphonic acid), H4P2O6 (hypodiphosphoric acid), H2S2O2/H2S2O3 (sulfoxylic-Zthiosulftiric acid), H2S2O4 (dithionic acid), H2SO3/H2S2O5 (sulfurous-Zdisulfiirous acid), R- S-OH (sulfenic acid) or R-S=0-OH (sulfinic acid) or and their ammonium, alkali metal or alkali earth metal salts; or a mixture of said reducing agents; with the proviso that the composition is essentially free of a polymerizable monomer. 2. The composition according to claim 1, wherein the reducing agent is a mixture of a cycilc ethylenically unsaturated compound having an allyhc hydrogen atom and a phosphorous compound according to claim 1 or a mixture of a cyclic ethylenically unsaturated compound having an allylic hydrogen atom and a sulfur compound according to claim 1. 3. The composition according to claim 1, wherein the reducing agent is H3PO2 (phosphinic acid), or a Na, K, Ca, Mg or ammonium salt thereof, with or without crystal water. 4. The composition according to claim 1, wherein the reducing agent is a cyclic mono-, sesqui- or di-terpene having an allylic hydrogen atom. 5. The composition according to claim 1, wherein the reducing agent is y-terpinene or a-phellandrene. 6. The composition according to claim 1, wherein the reducing agent is present in an amount of 0.01% to 5% based on the weight of the polymer. 7. A process for improving the color of polymers, obtainable by radical polymerization or grafting, which polymerization or grafting has been carried out in the presence of a stable free nitroxyl radical and a source of free radicals capable of initiating the polymerization, or in the presence of a nitroxyl ether , wherein X represents a group having at least one carbon atom and is such that the free radical derived from X is capable of -41- initiating polymerization and the remaining ' radical forms a stable free nitroxyl radical; by adding a reducing agent according to claim 1 to said polymer and heating said mixture to above the glass temperature in case of amorphous polymers or above the melting point in case of crystalline or semi-crystalline polymers; with the proviso that essentially no polymerizable monomer is present. 8. The process according to claim 7, wherein the mixture is heated to 50°-150°C above the glass temperature in case of amorphous polymers or 20°-180°C above the melting point in case of crystalline or semi-crystalline polymers.

Full Text

The invention relates to a composition and process for color improvement of nitroxyl or nitroxyl ether containing polymers.
Stable free nitrify radicals or nitrify ethers are for example useful in controlled free radical polymerization (CFRP) and by this way incorporated into the polymer in a significant amount, leading in some cases to slightly colored polymers.
Controlled free radical polymerization (CFRP) of ethylenically unsaturated monomers has attracted continuing attention, because of its capability to produce polymers with narrow molecular weight distributions and controlled architecture such as block copolymers.
US-A-4 581 429 to Solomon et a!., issued April 8,1986, discloses a free radical polymeriza¬tion process which controls the growth of polymer chains to produce short chain or oligo-meric photopolymers and copolymers, including block and graft copolymers. The process employs an initiator having the formula (in part) R'R"N-0-X, where X is a free radical species capable of polymerizing unsaturated monomers. The reactions typically have low conversion rates. Specifically mentioned radical R'R"N-0« groups are derived from 1,1,3,3 tetraethylisoindoline, 1,1,3,3 tetrapropylisoindoline, 2,2,6,6 tetramethylpiperidine, 2,2,5,5 tetramethylpyrrolidine or di-t-butylamine.
US 5322912 to Georges et al. issued June 21, 1994 discloses a polymerization process using a free radical initiator, a polymerizable monomer compound and a stable free radical agent of the basic structure R'R"N-0« for the synthesis of photopolymers and block copolymers.
WO 98/13392 describes open chain alkoxyamine compounds which have a symmetrical substitution pattern and are derived from NO gas or from nitro so compounds which are suitable regulators for this type of radical polymerization.
EP-A-621 878 and EP-A-735 052 disclose a method for preparing thermoplastic polymers of narrow polydispersities by free radical-initiated polymerization, which comprises adding a free radical initiator and a stable free radical agent to the monomer compound.

wo 96/24620 describes a polymerization process in which very specific stable free radical agents are used, such as for example bearing a hydrogen atom in
a-position to the nitrogen atom.
WO 98/30601 discloses specific nitroxyls based on Imldazolidinones, which are also useful for stable free radical mediated polymerization.
In addition WO 98/44008 discloses specific nitroxyls based on morpholinones, piperazinones and piperazinediones.
All nitroxyl radicals useful in such controlled polymerization processes have inherently a reddish color.
Polymers made in the presence of such stable nitroxyl radicals or nitroxyl ethers are end-capped by the nitroxyl group. The bond, polymer to nitroxyl group however is a labile bond, which cleaves upon heating, liberating again the nitroxyl radical and giving thus color to the polymer. The color formation depends, therefore, on the concentration of nitroxyl radical / nitroxylether used to synthesize the polymer.
As many processing conditions include a heating step, e. g. removing not reacted monomer, shaping parts by extrusion, injection molding, blow molding and the like, undesirable discoloration accompanies these processes.
The problem underlying the present invention is to counteract discoloration resulting from stable free nitroxyl radicals. This problem is solved by adding a reducing agent to the polymer, preferably during a processing step, such as extrusion or injection molding.
One subject of the invention is a composition comprising.

a) at least one oligomer, cooligomer, polymer or copolymer or blends thereof, containing a stable free nitroxyl radical ; and b) a reducing agent;
with the proviso that the composition is essentially free of a polymerizable monomer.
Essentially free of a polymerizable monomer means that in some cases there may be a small amount of monomer left from manufacturing the polymer, which could not be completely removed. Preferably no monomer at all is present. Usually the excess monomer is present in an amount of a few ppm.
The nitroxyl radical may be present due to its admixture during polymerization, due to its admixture for monomer stabilization, due to its use as chain stopping agent or due to a grafting reaction after polymerization has been completed.
The nitroxyl radical may be present as a mixture with the polymer or it may be partially bound to the polymer.
The polymers, copolymers, oligomers or cooligomers which can be used in the present invention are listed below.
1. Polymers of monoolefins and diolefins, for example polypropylene, polyisobutylene, po-lybut-1-ene, poly-4-methylpent-1-ene, polyisoprene or polybutadiene, as well as polymers of cycloolefins, for instance of cyclopentene or norbornene, polyethylene (which optionally can be crosslinked), for example high density polyethylene (HOPE), high density and high mole¬cular weight polyethylene (HDPE-HMW), high density and ultrahigh molecular weight poly¬ethylene (HDPE-UHMW), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), (VLDPE) and (ULDPE).
Polyolefins, i.e. the polymers of monoolefins exemplified in the preceding paragraph, prefe¬rably polyethylene and polypropylene, can be prepared by different, and especially by the following, methods:
a) radical polymerisation (normally under high pressure and at elevated temperature).

b) catalytic polymerisation using a catalyst that normally contains one or more than one metal of groups IVb, Vb, VIb or VIII of the Periodic Table. These metals usually have one or more than one ligand, typically oxides, halides, alcoholates, esters, ethers, amines, alkyls, alkenyls and/or aryls that may be either p- or s-coordinated. These metal complexes may be in the free form or fixed on substrates, typically on activated magnesium chloride, titanium(lli) chloride, alumina or silicon oxide. These catalysts may be soluble or Insoluble in the polymerisation medium. The catalysts can be used by themselves in the polymerisation or further activators may be used, typically metal alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyloxanes, said metals being elements of groups la, lla and/or Ilia of the Periodic Table. The activators may be modified conveniently with further ester, ether, amine or silyl ether groups. These catalyst systems are usually termed Phillips, Standard Oil Indiana, Ziegler (-Natta), TNZ (DuPont), metallocene or single site catalysts (SSC).
2. Mixtures of the polymers mentioned under 1), for example mixtures of polypropylene with polyisobutylene, polypropylene with polyethylene (for example PP/HDPE, PP/LDPE) and mixtures of different types of polyethylene (for example LDPE/HDPE).
3. Copolymers of monoolefins and diolefins with each other or with other vinyl monomers, for example ethylene/propylene copolymers, linear low density polyethylene (LLDPE) and mixtures thereof with low density polyethylene (LDPE), propylene/but-1-ene copolymers, propylene/isobutylene copolymers, ethylene/but-1-ene copolymers, ethylene/hexene copo¬lymers, ethylene/methylpentene copolymers, ethylene/heptene copolymers, ethylene/octene copolymers, propylene/butadiene copolymers, isobutylene/isoprene copolymers, ethy-lene/alkyl acrylate copolymers, ethylene/alkyi methacrylate copolymers, ethylene/vinyl ace¬tate copolymers and their copolymers with carbon monoxide or ethylene/acrylic acid copo¬lymers and their salts (ionomers) as well as terpolymers of ethylene with propylene and a diene such as hexadiene, dicyclopentadiene or ethylidene-norbornene; and mixtures of such copolymers with one another and with polymers mentioned in 1) above, for example polypropylene/ethylene-propylene copolymers, LDPE/ethylene-vinyl acetate copolymers (EVA), LDPE/ethylene-acrylic acid copolymers (EAA), LLDPE/EVA, LLDPE/EAA and alter-

nating or random polyalkylene/carbon monoxide copolymers and mixtures thereof with other polymers, for example polyamides.
4. Polystyrene, poly(p-methylstyrene), poly(a-methylstyrene).
5. Copolymers of styrene or a-methylstyrene with dienes or acrylic derivatives, for example styrene/butadiene, styrene/acrylonitrile, styrene/alkyi methacrylate, styrene/butadiene/alkyi acrylate, styrene/butadiene/alkyi methacrylate, styrene/maleic anhydride, styrene/acryloni-trile/methyl acrylate; mixtures of high impact strength of styrene copolymers and another polymer, for example a polyacrylate, a diene polymer or an ethylene/propylene/diene terpo-lymer; and block copolymers of styrene such as styrene/butadiene/styrene, styrene/iso-prene/styrene, styrene/ethylene/butylene/styrene or styrene/ethylene/propylene/ styrene.
6. Graft copolymers of styrene or a-methylstyrene, for example styrene on polybutadiene, styrene on polybutadiene-styrene or polybutadiene-acrylonitrile copolymers; styrene and acrylonitrile (or methacrylonitrile) on polybutadiene; styrene, acrylonitrile and methyl meth¬acrylate on polybutadiene; styrene and maleic anhydride on polybutadiene; styrene, acrylo¬nitrile and maleic anhydride or maleimide on polybutadiene; styrene and maleimide on poly¬butadiene; styrene and alkyl acrylates or methacrylates on polybutadiene; styrene and acry¬lonitrile on ethylene/propylene/diene terpolymers; styrene and acrylonitrile on polyalkyi acry¬lates or polyalkyi methacrylates, styrene and acrylonitrile on acrylate/butadiene copolymers, as well as mixtures thereof with the copolymers listed under 6), for example the copolymer mixtures known as ABS, MBS, ASA or AES polymers.
7. Polymers derived from a,p-unsaturated acids and derivatives thereof such as polyacry-lates and polymethacrylates; polymethyl methacrylates, polyacrylamides and polyacryloni-triles, impact-modified with butyl acrylate.
8. Copolymers of the monomers mentioned under 7) with each other or with other unsatu¬rated monomers, for example acrylonitrile/ butadiene copolymers, acrylonitrile/alkyi acrylate copolymers, acrylonitrile/alkoxyalkyi acrylate or acrylonitrile/vinyl halide copolymers or acry¬lonitrile/ alkyl methacrylate/butadiene terpolymers.

9. Polymers derived from unsaturated alcohols and amines or the acyl derivatives or acetals
thereof, for example polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl
benzoate, polyvinyl maleate, polyvinyl butyral, polyallyl phthalate or polyallyl melamine; as
well as their copolymers with olefins mentioned in 1) above.
10. Homopolymers and copolymers of cyclic ethers such as polyalkylene glycols, polyethy¬lene oxide, polypropylene oxide or copolymers thereof with bisglycidyl ethers.
11. Polyacetals such as polyoxymethylene and those polyoxymethylenes which contain ethylene oxide as a comonomer; polyacetals modified with thermoplastic polyurethanes, acrylates or MBS.
12. Polyphenylene oxides and sulfides, and mixtures of polyphenylene oxides with styrene polymers or polyamides.
13. Polyurethanes derived from hydroxyl-terminated polyethers, polyesters or polybutadi-enes on the one hand and aliphatic or aromatic polyisocyanates on the other, as well as precursors thereof.
14. Polyamides and copolyamides derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, for example polyamide 4, polyamide 6, polyamide 6/6, 6/10, 6/9, 6/12, 4/6, 12/12, polyamide 11, polyamide 12, aromatic polyamides starting from m-xylene diamine and adipic acid; polyamides prepared from hexamethylenediamine and isophthalic or/and terephthalic acid and with or without an ela¬stomer as modifier, for example poly-2,4,4,-trimethylhexamethylene terephthalamide or poly-m-phenylene isophthalamide; and also block copolymers of the aforementioned polyamides with polyolefins, olefin copolymers, ionomers or chemically bonded or grafted elastomers; or with polyethers, e.g. with polyethylene glycol, polypropylene glycol or polytetramethylene glycol; as well as polyamides or copolyamides modified with EPDM or ABS; and polyamides condensed during processing (RIM polyamide systems).
15. Polyureas, polyimides, polyamide-imides, polyetherimids, polyesterimids, polyhydantoins and polybenzimidazoles.

16. Polyesters derived from dicarboxylic acids and diols and/or from hydroxycarboxylic acids
or the corresponding lactones, for example polyethylene terephthalate, polybutylene
terephthalate, poly-1,4-dimethylolcyciohexane terephthalate and polyhydroxybenzoates, as
well as block copolyether esters derived from hydroxyl-terminated polyethers; and also poly¬
esters modified with polycarbonates or MBS.
17. Polycarbonates and polyester carbonates.
18. Polysulfones, polyether sulfones and polyether ketones.
19. Blends of the aforementioned polymers (polyblends), for example PP/EPDM, Poly-amide/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS, PBTP/ABS, PC/ASA, PC/PBT, PVC/CPE, PVC/acrylates, POM/thermoplastic PUR, PC/thermoplastic PUR, POM/acrylate, POM/MBS, PPO/HIPS, PPO/PA 6.6 and copolymers, PA/HDPE, PA/PP, PA/PPO, PBT/PC/ABS or PBT/PET/PC.
Preferred is a composition, comprising a) at least one oligomer, cooligomer, polymer or copolymer, obtained by radical polymerization, which polymerization has been carried out in
the presence of a stable free nitroxyl radical and a source of free radicals
capable of initiating polymerization, or in the presence of a nitroxyl ether
wherein X represents a group having at least one carbon atom and is such that the free radical derived from X is capable of initiating polymerization and the remaining
radical forms a stable free nitroxyl radical; and b) a reducing agent;
with the proviso that the composition is essentially free of a polymerizable monomer.
As mentioned before controlled free radical polymerization of ethylenically unsaturated monomers in the presence of nitroxyl radicals or nitroxyl ethers is a known process

described in numerous prior art documents. Stable free radicals having a structural element

principal known. Suitable compounds and their manufacture are for example described in US 4 581 429, US 5 721 320, US 5627 248, WO 98/13392 , WO98/30601 or in WO 98/44008.
Further suitable initiator/regulator compounds and their preparation are described in GB 2 335 190.

Another preferred class of initiator/regulator compounds is described in the British patent application GB 2 342 649 .
Typically the ethylenically unsaturated monomer or oligomer usefull in controlled polymerization processes is selected from the group consisting of ethylene, propylene, n-butylene, i-butylene, styrene, substituted styrene, conjugated dienes, acrolein, vinyl acetate, vinylpyrrolidone, vinylimidazoie, maleic anhydride, (alkyl)acryiic acidanhydrides, (alkyl)acryiic acid salts, (alkyl)acrylic esters, (meth)acrylonitriles, (alkyl)acrylamides, vinyl halides or vinylidene halides.

Preferred ethylenically unsaturated monomers are ethylene, propylene, n-butylene, i-butylene, isoprene, 1,3-butadiene, a-Cs-Cisalkene, styrene, a-methyl styrene, p-methyl styrene or a compound of formula CH2=C(Ra)-(C=Z)-Rb, wherein Ra is hydrogen or Cr C4 alkyl, Rb is NH2, 0'(Me*), glycidyl, unsubstituted C1-C18alkoxy, Cj-Ciooalkoxy interrupted by at least one N and/or O atom, or hydroxy-substituted C1-C18alkoxy, unsubstituted d-Ciaalkylamino, di(Ci-Ci8alkyl)amino, hydroxy-substituted Ci-Cisalkylamino or hydroxy-substituted di(Ci-Ci8alkyl)amino, -0-CH2-CH2-N(CH3)2 or -0-CH2-CH2-N'H(CH3)2 An"; An" Is a anion of a monovalent organic or inorganic acid; Me is a monovalent metal atom or the ammonium ion. Z is oxygen or sulfur.
Examples of acids from which the anion An" is derived are Ci-Ci2carboxylic acids, organic sulfonic acids such as CF3SO3H or CH3SO3H, mineralic acids such as HCI, HBr or HI, 0x0 acids such as HCIO4 or complex acids such as HPFe or HBF4.
Examples for Rg as C2-Ciooalkoxy interrupted by at least one O atom are of formula
, wherein Re is Ci-C25alkyl, phenyl or phenyl substituted by Cr
C18 alkyl, Rd is hydrogen or methyl and v is a number from 1 to 50. These monomers are for example derived from non ionic surfactants by acrylation of the corresponding alkoxylated alcohols or phenols. The repeating units may be derived from ethylene oxide, propylene oxide or mixtures of both.
Further examples of suitable acrylate or methacrylate monomers are given below.
An", wherein An"
and Ra have the meaning as defined above and Re is methyl or benzyl. An" is preferably CI", Br'or"O3S-CH3.

Particularly preferred ethylenically unsaturated monomers are styrene, methylacrylate, ethylacrylate, butylacrylate, isobutylacrylate, tert. butylacrylate, hydroxyethylacrylate, hydroxypropylacrylate, dimethylaminoethylacrylate, glycidylacrylates, methyl(meth)acrylate, ethyi(meth)acrylate, butyl(meth)acry!ate, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, dimethylamlnoethyl(meth)acrylate, glycldyl(meth)acrylates, acrylonltrile, acrylamide, methacrylamide or dimethylamlnopropyl-methacrylamide.
The polymerization process may be carried out in the presence of an organic solvent or in the presence of water or in mixtures of organic solvents and water. Additional cosolvents or surfactants, such as glycols or ammonium salts of fatty acids, may be present. Other suitable cosolvents are described hereinafter.
If organic solvents are used, suitable solvents or mixtures of solvents are typically pure alkanes (hexane, heptane, octane, isooctane), aromatic hydrocarbons (benzene, toluene, xylene), halogenated hydrocarbons (chlorobenzene), aikanols (methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether), esters (ethyl acetate, propyl, butyl or hexyl acetate) and ethers (diethyl ether, dibutyl ether, ethylene glycol dimethyl ether), or mixtures thereof.
The aqueous polymerization reactions can be supplemented with a water-miscible or hydrophilic cosolvent to help ensure that the reaction mixture remains a homogeneous single phase throughout the monomer conversion. Any water-soluble or water-miscible cosolvent may be used, as long as the aqueous solvent medium is effective in providing a solvent system which prevents precipitation or phase separation of the reactants or polymer products until after all polymerization reactions have been completed. Exemplary cosolvents useful in the present invention may be selected from the group consisting of aliphatic alcohols, glycols, ethers, glycol ethers, pyrrolidines, N-alkyI pyrrolidinones, N-alkyI pyrrolidones, polyethylene glycols, polypropylene glycols, amides, carboxylic acids and salts thereof, esters, organosulfides, sulfoxides, sulfones, alcohol derivatives, hydroxyether derivatives such as butyl carbitol or cellosolve, amino alcohols, ketones, and the like, as well as derivatives thereof and mixtures thereof. Specific examples include methanol, ethanol, propanol, dioxane, ethylene glycol, propylene glycol, diethylene glycol, glycerol, dipropylene glycol, tetrahydrofuran, and other water-soluble or water-miscible materials, and mixtures thereof. When mixtures of water and water-soluble or water-miscible organic liquids are selected as the aqueous reaction media, the water to cosolvent weight ratio is typically in the range of about 100:0 to about 10:90.

Furthermore CFRP is particularly useful for the preparation of block copolymers.
Block copolymers are, for example, block copolymers of polystyrene and polydienes or polyacrylates (e.g., poly(styrene-b-butadiene), poly(styrene-b-isoprene), poly(styrene-£)-acrylate) or poly(styrene-j!)-acrylate-i)-styrene). They are usefull as adhesives or as compatibilizers for polymer blends or as polymer toughening agents. Poly(methylmethacrylate-6-acrylate) diblock copolymers or poly(methylacrylate-6-acrylate-6-methacrylate) triblock copolymers) are useful as dispersing agents for coating systeme, as coating additives (e.g. Theological agents, compatibilizers, reactive diluents) or as resin component in coatings(e.g. high solid paints) Block copolymers of styrene, (meth)acrylates and/or acrylonitrile are useful for plastics, elastomers and adhesives.
Block copolymers prepared by CFRP, wherein the blocks alternate between polar monomers and non-polar monomers, are useful in many applications as amphiphilic surfactants or dispersants for preparing highly uniform polymer blends.
The (co)polymers may have a number average molecular weight from 1 000 to 400000 g/mol, preferably from 2 000 to 250 000 g/mol and, more preferably, from 2 000 to 200 000 g/mol. The number average molecular weight may be determined by size exclusion chromatography (SEC), matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) or, if the initiator carries a group which can be easily distinguished from the monomer(s), by NMR spectroscopy or other conventional methods.
A plurality of specifically designed polymers and copolymers are accessible by this type of controlled radical polymerization, such as star and graft (co)polymers as described, inter alia, by C. J. Hawker in Angew. Chemie, 1995, 107, pages 1623-1627, dendrimers as described by K. Matyaszewski et al. in Macromolecules 1996, Vol 29, No. 12, pages 4167-4171, graft (co)polymers as described by C. J. Hawker et al. in Macromol. Chem. Phys. 198, 155-166(1997), random copolymers as described by C. J. Hawker in Macromolecules 1996, 29, 2686-2688, or diblock and triblock copolymers as described by N. A. Listigovers in Macromolecules 1996, 29, 8992-8993.
Preferably the reducing agent is a cyclic ethylenically unsaturated compound having an aliylic hydrogen atom, a phosphorous compound with oxidation number l-IV and a valence of

3 to 5 or a sulfur compound with oxidation number l-IV and a valence of 2 or 4 or a mixture thereof.
Particularly preferred is a composition, wherein the reducing agent is a mixture of a cyclic ethylenically unsaturated compound having an allylic hydrogen atom and a phosphorous compound with oxidation number l-IV and a valence of 3 to 5 or a sulfur compound with oxidation number l-IV and a valence of 2 to 4.

Suitable organic phosphorous compounds are R'-H2P02, R'R"HPO or R'R"HP03, P(0R)3 wherein R' and R" independently are C1 - C18 AralkyI, phenyl or C1-C18alkyl.
Also suitable organic phosphites and phosphonites are for example triphenyl phosphite, diphenyl alkyl phosphites, phenyl dialkyi phosphites, tris(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)-pentaerythritol diphosphite, diisodecyloxypentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl)pentaerythritol diphosphite, bis(2,4,6-tris(tert-butyiphenyl)pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakls(2,4-di-tert-butylphenyl) 4,4'-biphenylene diphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenz[d,g]-1,3,2-dioxaphosphocin, 6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenz[d,g]-1,3,2-dioxaphosphocin, bis(2,4-di-tert-butyl-6-methylphenyl) methyl phosphite, bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite, 2,2',2"-nitrilo-[triethyltris(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl)phosphite], 2-ethylhexyl(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl)phosphite.
Especially preferred are the following phosphites:

Particularly preferred sulfur compounds are:
H2S2O2/H2S2O3 sulfoxylic-/ thlosulfuric acid
H2S2O4 dithionic acid
H2SO3/H2S2O5 sulfurous-Zdisulfurous acid
R-S-OH sulfenic acid
R-S=0-OH sulfinic acid
and their amonium, alkali or alkali earth salts. The salts may also contain crystal water.
Typically the alkali or alkali earth metal is Li, Na, K, Ca, Mg. The salts can contain additional crystal water.
Most preferred are H3PO2 (phosphinic acid), or a Na, K, Ca, Mg or ammonium salt thereof, with or without crystal water.
Particularly preferred is NaH2P02 which may contain additional crystal water.
Examples of cyclic ethylenically unsaturated compounds are dihydroanthacene and dihydronaphtaline and their derivatives, wherein RrRe independently are H, alkyl, cycloalkyi, aryl, aralkyi, alkenyl, alkinyl or COOalkyl. The aromatic radicals may also be further substituted.

The substituents R29-R50 have the same meaning as given for Ri-Re and L2 is a number from 1-100.
Preferably the meaning of R1-R50 is hydrogen or Ci-C4a!kyl.
Preferably the reducing agent is a cyclic mono-, sesqui- or di-terpene having an allylic hydrogen atom.
Examples are a-terpinene, y-terpinene, a-phellandrene, p-phellandrene, limonene, a-pinene, p-pinene, a-terpineol, cadinene, p-selinene, p-lonone, abietic acid.
Most preferred are y-terpinene and a-phellandrene.
The reducing agent is preferably present in an amount of from 0.01% to 5%, more preferably from of from 0.05% to 3%, based on the weight of the polymer.
The concentration to be used depends on the amount of nitroxyl present in the oligomer or polymer. Obviously for high concentrations of nitroxyl, high concentrations of the reducing agent are used. Furthermore it depends on the color improvement (color stability of the polymer) to be targeted
If a mixture of a cyclic ethylenically unsaturated compound having an allylic hydrogen atom (a) and a phosphorous compound with oxidation number l-IV and a valence of 3 to 5 (b) is used, the ratio (a):(b) may vary from 1:10 to 10:1, preferably it is from 1:5 to 5:1 and most preferably from 1:2 to 2:1.
The composition can also contain further additives. Examples are given below.

1. Antioxidants
1.1. Alkylated monophenols. for example 2,6-di-tert-buty!-4-methylphenol, 2-tert-butyl-4,6-di-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-bu-tyl-4-isobutyiphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(a-methylcyclohexyl)-4,6-dimethyl-phenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-trJcyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, nonylphenols which are linear or branched in the side chains, for example, 2,6-di-nonyl-4-methylphenol, 2,4-dimethyl-6-(1'-methylundec-1'-yl)phenol, 2,4-di-methyl-6-(1 '-methylheptadec-1 '-yl)phenol, 2,4-dimethyl-6-(1 '-methyltridec-1 '-yl)phenol and mixtures thereof.
1.2. Alkylthiomethylphenols. for example 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,4-dioc-tylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-di-dodecylthiomethyl-4-nonylphenol.
1.3. Hydroquinones and alkylated hydroquinones. for example 2,6-di-tert-butyl-4-methoxy-phenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octade-cyloxyphenol, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl stearate, bis-(3,5-di-tert-butyl-4-hydroxyphenyl) adipate.
1.4. Tocopherols, for example a-tocopherol, b-tocopherol, g-tocopherol, d-tocopheroi and mixtures thereof (Vitamin E).
1.5. Hydroxylated thiodiphenvl ethers, for example 2,2'-thiobis(6-tert-butyl-4-methylphenol), 2,2'-thiobis(4-octylphenol), 4,4'-thiobis(6-tert-butyl-3-methylphenol), 4,4'-thiobis(6-tert-butyl-2-methylphenol), 4,4'-thiobis-(3,6-di-sec-amylphenol), 4,4'-bis(2,6-dimethyl-4-hydroxyphe-nyl)disulfide.
1.6. Alkylidenebisphenols. for example 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), 2,2'-methylenebis[4-methyl-6-(a-methylcyclohexyl)-phenol], 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis(6-nonyl-4-me-thylphenol), 2,2'-methylenebis(4,6-di-tert-butylphenol), 2,2'-ethylidenebis(4,6-di-tert-butyl-

phenol), 2,2'-ethylidenebis(6-tert-butyl-4-isobutylphenol), 2,2'-methylenebis[6-(a-methylben-zyl)-4-nonylphenol], 2,2'-methylenebis[6-(a,a-dimethylbenzyl)-4-nonylphenol], 4,4'-methy-lenebis(2,6-di-tert-butylphenol), 4,4'-methylenebis(6-tert-butyl-2-methylphenol), 1,1-bis(5-tert-buty!-4-hydroxy-2-methylpheny()butane, 2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 1,1 -bis(5-tert-butyl-4-hydroxy-2-methyl-phenyl)-3-n-dodecylmercaptobutane, ethylene glycol bls[3,3-bis(3'-tert-butyl-4'-hydroxyphenyl)butyrate], bis(3-tert-butyl-4-hydroxy-5-methyl-phenyl)dicyclopentadi-ene, bis[2-(3'-tert-butyl-2'-hydroxy-5'-methylbenzyl)-6-tert-butyl-4-methylphenyl]terephthalate, 1,1-bis-(3,5-dimethyl-2-hydroxyphenyl)butane, 2,2-bls-(3,5-dl-tert-butyl-4-hydroxyphe-nyl)propane, 2,2-bis-(5-tert-butyl-4-hydroxy2-methylphenyl)-4-n-dodecylmercaptobutane, 1,1,5,5-tetra-(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane.
1.7. 0-. N- and S-benzvl compounds, for example 3,5,3',5'-tetra-tert-butyl-4,4'-dlhydroxydi-benzyl ether, octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate, tridecyl-4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)amine, bjs(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dlthioterephthalate, bis(3,5-di-tert-butyl-4-hydroxy-benzyl)sulfide, isooctyl-3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate.
1.8. Hydroxybenzvlated maionates, for example dioctadecyl-2,2-bis-(3,5-di-tert-butyl-2-hy-droxybenzyl)-malonate, dl-octadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)-malonate, di-dodecylmercaptoethyl-2,2-bls-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, bls[4-(1,1,3,3-te-tramethylbutyl)phenyl]-2,2-bls(3,5-dJ-tert-butyl-4-hydroxybenzyl)malonate.
1.9. Aromatic hydroxybenzyl compounds, for example 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxy-benzyl)-2,4,6-trimethylbenzene, 1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetrame-thylbenzene, 2,4,6-tris(3,5-dl-tert-butyl-4-hydroxybenzyl)phenol.
1.10. Triazine Compounds, for example 2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl-4-hy-
droxyanillno)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanillno)-1,3,5-
triazlne, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine, 2,4,6-
tris(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,2,3-triazine, 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxy-
benzyl)isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dlmethylbenzyl)isocyanurate, 2,4,6-
tris(3,5-dl-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine, 1,3,5-tris(3,5-di-tert-butyl-4-

hydroxyphenylpropionyl)-hexahydro-1,3,5-triazine, 1,3,5-tris(3,5-dicyclohexyl-4-hydroxyben-zyl)isocyanurate.
1.11. Benzylphosphonates, for example dimethyl-2,5-di-tert-butyl-4-hydroxybenzylphospho-nate, diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl3,5-di-tert-butyl-4-hy-droxybenzylphosphonate, dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, the calcium salt of the monoethyl ester of 3,5-dl-tert-butyl-4-hydroxybenzylphosphonic acid.
1.12. Acvlaminophenols. for example 4-hydroxylauranilide, 4-hydroxystearanilide, octyl N-(3,5-di-tert-butyl-4-hydroxyphenyl)carbamate.
1.13. Esters of b-(3.5-di-tert-butvl-4-hvdroxvphenvl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethy-lene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N'-bis(hy-droxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylol-propane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.
1.14. Esters of b-(5-tert-butvl-4-hvdroxv-3-methvlphenvl)propionic acid with mono- or poly¬hydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexane¬diol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N'-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.
1.15. Esters of b-(3.5-dicvclohexvl-4-hvdroxvphenvl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N'-bis(hydroxyethyl)ox-amide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hy-droxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.
1.16. Esters of 3,5-di-tert-butvl-4-hvdroxvphenvl acetic acid with mono- or polyhydric alco¬hols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol,

ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythrltol, tris(hydroxyethyl)isocyanurate, N,N'-bis(hydroxyethyl)ox-amide, 3-thlaundecanol, 3-thlapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hy-droxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.
1.17. Amides of b-(3,5-di-tert-butvl-4-hvdroxvphenvl)proplonic acid e.g. N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylproplonyl)hexamethylenediamide, N,N'-bls(3,5-dl-tert-butyl-4-hydroxy-phenylpropionyl)trimethylenediamlde, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)-hydrazide, N,N'-bis[2-(3-[3,5-di-tert-butyl-4-hydroxypheny!]propionyloxy)ethyl]oxamide (Naugard®XL-1 supplied by Unlroyal).
1.18. Ascorbic acid (vitamin C)
1.19. Aminic antioxidants, for example N,N'-di-isopropyl-p-phenylenediamine, N,N'-di-sec-butyl-p-plnenylenediamine, N,N'-bis(1,4-dimetliylpentyl)-p-phenylenediamine, N,N'-bis(1-etliyl-3-methylpenty!)-p-phenylenediamine, N,N'-bis(1-metliylheptyl)-p-phenylenediamine, N,N'-dicyclolnexyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-bis(2-naph-tiiyl)-p-phenylenediamine, N-isopropyl-N'-piienyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-{1 -methylheptyl)-N'-plienyl-p-phenylenediamine, N-cyclo-hexyl-N'-phenyl-p-phenlenediamine, 4-(p-toluenesulfamoyl)diphenylamine, N,N'-dimethyl-N,N'-di-sec-butyl-p-plienylenediamine, diphenylamine, N-allyldiphenylamine, 4-isopropoxy-diphenylamine, N-ptienyl-1-naphtliylamine, N-(4-tert-octylphenyl)-1-naphthylamine, N-phe-nyi-2-naphthylamine, octylated diphenylamine, for example p,p'-di-tert-octyldiphenylamine, 4-n-butylaminophenol, 4-butyrylaminophenol, 4-nonanoylaminophenol, 4-dodecanoylamino-phenol, 4-octadecanoylaminophenol, bis(4-methoxyphenyl)amine, 2,6-di-tert-butyl-4-dime-thylaminomethylphenol, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, N,N,N',N'-tetramethyl-4,4'-diaminodiphenylmethane, 1,2-bis[(2-methylphenyl)amino]ethane, 1,2-bis(phenylamino)propane, (o-tolyl)biguanide, bis[4-(r,3'-dimethylbutyl)phenyl]amine, tert-octylated N-phenyl-1-naphthylamine, a mixture of mono- and dialkylated tert-butyl/tert-octyldiphenylamines, a mixture of mono- and dialkylated nonyldiphenylamines, a mixture of mono- and dialkylated dodecyldiphenylamines, a mixture of mono- and dialkylated isopro-pyl/isohexyldiphenylamines, a mixture of mono- und dialkylated tert-butyidiphenylamines, 2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, a mixture of mono- und dial¬kylated tert-butyl/tert-octylphenothiazines, a mixture of mono- und dialkylated tert-octyl-phe-

nothiazines, N-allylphenothiazin, N,N,N',N'-tetraphenyl-1,4-diaminobut-2-ene, N,N-bis-(2,2,6,6-tetramethyl-piperid-4-yl-hexamethylenediamine, bis(2,2,6,6-tetrannethylpiperid-4-yl)-sebacate, 2,2,6,6-tetramethylpiperidin-4-one, 2,2,6,6-tetramethylpiperidin-4-ol.
2. UV absorbers and light stabilisers
2.1 ■ 2-(2'-HvdroxvDhenvi)benzotriazoles. for example 2-(2'-hydroxy-5'-methylphenyl)-ben2o-triazole, 2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(5'-tert-butyl-2'-hydroxyphe-nyl)benzotriazole, 2-(2'-hydroxy-5'-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole, 2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-methylphe-nyl)-5-chloro-benzotriazole, 2-(3'-sec-butyl-5'-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-4'-octyloxyphenyl)benzotriazole, 2-(3',5'-di-tert-amyl-2'-hydroxyphenyl)benzotriazole, 2-(3',5'-bis-(a,a-dimethylbenzyl)-2'-hydroxyphenyl)benzotria2ole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-{3'-tert-butyl-5'-[2-(2-ethylhexyloxy)-carbonylethyl]-2'-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-2'-hy-droxy-5'-(2-methoxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-methoxycarbonylethyl)phenyl)benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-octyloxy-carbonylethyl)phenyl)benzotriazole, 2-(3'-tert-butyl-5'-[2-(2-ethylh6xyloxy)carbonylethyl]-2'-hydroxyphenyl)benzotriazole, 2-(3'-dodecyl-2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-isooctyIoxycarbonylethyl)phenylbenzotriazole, 2,2'-methylene-bis-[4-(1,1,3,3-tetramethylbutyl)-6-benzotriazole-2-ylphenol]; the transesterification product of 2-[3'-tert-butyl-5'-(2-methoxycarbonylethyl)-2'-hydroxyphenyl]-2H-benzotriazole with polyethy¬lene glycol 300; [R-CHJCHJ-COO-CHJCHJ-^ where R = 3'-tert-butyl-4'-hydroxy-5'-2H-
benzotriazol-2-ylphenyl, 2-[2'-hydroxy-3'-(a,a-dimethylbenzyl)-5'-(1,1,3,3-tetramethylbutyl)-phenyl]benzotriazole; 2-[2'-hydroxy-3'-(1,1,3,3-tetramethylbutyl)-5'-(a,a-dimethylbenzyl)-phenyl]benzotriazole.
2.2. 2-Hvdroxvbenzophenones. for example the 4-hydroxy, 4-methoxy, 4-octyloxy, 4-decyl-oxy, 4-dodecyloxy, 4-benzyloxy, 4,2',4'-trihydroxy and 2'-hydroxy-4,4'-dimethoxy derivatives.
2.3. Esters of substituted and unsubstituted benzoic acids, as for example 4-tertbutyl-phenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoyi resorcinol, bis(4-tert-butylben-zoyl) resorcinol, benzoyl resorcinol, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzo-

ate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl 3,5-di-tert-butyl-4-hydroxy-benzoate, 2-methyl-4,6-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate.
2.4. Acrylates. for example ethyl a-cyano-b,b-diphenylacrylate, isooctyl a-cyano-b,b-diphe-nylacrylate, methyl a-carbomethoxycinnamate, methyl a-cyano-b-methyl-p-methoxy-clnna-mate, butyl a-cyano-b-methyl-p-methoxy-cinnamate, methyl a-carbomethoxy-p-methoxycln-namate and N-(b-carbomethoxy-b-cyanovlnyl)-2-methyllndoline.
2.5. Nickel compounds, for example nickel complexes of 2,2'-thio-bis-[4-(1,1,3,3-tetrame-thylbutyl)phenol], such as the 1:1 or 1:2 complex, with or without additional ligands such as n-butylamine, triethanolamine or N-cyclohexyldiethanolamine, nickel dibutyldithiocarbamate, nickel salts of the monoalkyi esters, e.g. the methyl or ethyl ester, of 4-hydroxy-3,5-di-tert-butylbenzylphosphonic acid, nickel complexes of ketoximes, e.g. of 2-hydroxy-4-methylphe-nyl undecylketoxime, nickel complexes of 1-phenyl-4-lauroyl-5-hydroxypyrazole, with or without additional ligands.
2.6. Stericallv hindered amines, for example bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl)succinate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(1 -octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-pi-peridyl) n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensate of 1-(2-hydroxy-ethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, linear or cyclic condensates of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-tert-octylamino-2,6-dichloro-1,3,5-triazine, tris(2,2,6,6-tetramethyl-4-piperidyl)nitrilotriacetate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate, 1,1'-(1>2-ethanediyl)-bis(3,3,5,5-tetramethylpiperazinone), 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate, 3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decan-2,4-dione, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)sebacate, bis(1-octyloxy-2,2,6,6-tetrame-thylpiperidyl)succinate, linear or cyclic condensates of N,N'-bis-(2,2,6,6-tetramethyl-4-piperi-dyl)hexamethylenediamine and 4-morpholino-2,6-dichloro-1,3,5-triazine, the condensate of 2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl )-1,3,5-triazine and 1,2-bis(3-aminopropylamino)ethane, the condensate of 2-chloro-4,6-di-(4-n-butylamino-1,2,2,6,6-pen-tamethylpiperidyl)-1,3,5-triazine and 1,2-bis-(3-aminopropylamino)ethane, 8-acetyl-3-dode-cyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione, 3-dodecyl-1-(2,2,6,6-tetrame-

thyl-4-piperidyl)pyrrolidin-2,5-dione, 3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrroli-dine-2,5-dione, a mixture of 4-hexadecyloxy- and 4-stearyloxy-2,2,6,6-tetramethylpiperidine, a condensation product of N,N'-bis(2,2,6,6-tetrametiiyl-4-piperidyl)hexamethylenediamine and 4-cyclohexylamino-2,6-dichloro-1,3,5-triazine, a condensation product of 1,2-bis(3-ami-nopropylamino)etiiane and 2,4,6-trichloro-1,3,5-triazine as well as 4-butylamino-2,2,6,6-te-tramethylpiperidine (CAS Reg. No. [136504-96-6]); N-(2,2,6,6-tetramethyl-4-piperidyl)-n-do-decylsuccinimid, N-(1,2,2,6,6-pentamethyl-4-piperidyi)-n-dodecylsuccinimid, 2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4,5]decane, a reaction product of 7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro [4,5]decane und epichlorohydrin, 1,1-bis(1,2,2,6,6-pentannethyl-4-piperidyloxycarbonyl)-2-(4-metiioxyphenyl)ethene, N,N'-bis-formyl-N,N'-bis(2,2,6,6-tetrametlnyl-4-piperidyl)hexamethylenediamine, diester of 4-methoxy-metliyiene-malonic acid with 1,2,2,6,6-pentamethyi-4-hydroxypiperidine, poly[methylpropyl-3-oxy-4-(2,2,6,6-tetrametiiyl-4-piperidyi)]siloxane, reaction product of maleic acid anhydride-a-olefin-copoiymer with 2,2,6,6-tetramethyl-4-aminopiperidine or 1,2,2,6,6-pentamethyl-4-aminopiperidine.
2.7. Oxamides, for example 4,4'-dioctyloxyoxanilide, 2,2'-diethoxyoxanilide, 2,2'-dioctyloxy-5,5'-di-tert-butoxanilide, 2,2'-didodecyloxy-5,5'-di-tert-butoxanilide, 2-ethoxy-2'-ethyloxanilide, N,N'-bis(3-dimethylaminopropyl)oxamide, 2-ethoxy-5-tert-butyi-2'-ethoxanilide and its mixture with 2-ethoxy-2'-ethyl-5,4'-di-tert-butoxanilide, mixtures of o- and p-methoxy-disubstituted oxanllides and mixtures of o- and p-ethoxy-disubstituted oxaniiides.
2.8. 2-(2-Hvdroxvphenvi)-1.3.5-triazines, for example 2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxypheny!)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-pro-pyloxyphenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis-(4-methylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-bis(2,4-dimethylphe-nyl)-1,3,5-triazine, 2-(2-hydroxy-4-tridecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-tri-azine, 2-[2-hydroxy-4-(2-hydroxy-3-butyloxy-propoxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3,5-tri¬azine, 2-[2-hydroxy-4-(2-hydroxy-3-octyloxy-propyloxy)phenyl]-4,6-bls(2,4-dimethyl)-1,3,5-triazine, 2-[4-(dodecyloxy/tridecyloxy-2-hydroxypropoxy)-2-hydroxy-phenyl]-4,6-bis(2,4-di-methylphenyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-dodecyloxy-propoxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-hexyloxy)phenyl-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4,6-tris[2-hydroxy-4-(3-

butoxy-2-hydroxy-propoxy)phenyl]-1,3,5-tria2ine, 2-(2-hydroxyphenyl)-4-(4-methoxyphenyl)-6-phenyl-1,3,5-triazine, 2-{2-hydroxy-4-[3-(2-ethylhexyl-1-oxy)-2-hydroxypropyloxy]phenyl}-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine.
3. Metal deactivators, for example N,N'-dlphenyloxamide, N-sallcylal-N'-salicyloyI hydrazine, N,N'-bis(salicyloyl) hydrazine, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hydrazine, 3-salicyloylamino-1,2,4-triazole, bis(benzylidene)oxalyl dihydrazide, oxanilide, isophthaloyi dihydrazide, sebacoyi bisphenylhydrazide, N,N'-diacetyladipoyl dihydrazide, N,N'-bis(salicyl-oyl)oxalyl dihydrazide, N,N'-bis(salicyloyl)thiopropionyl dihydrazide.
4. Hvdroxvlamines. for example, N,N-dibenzylhydroxylamine, N,N-diethylhydroxylamine, N,N-dioctylhydroxylamine, N,N-dilaurylhydroxylamine, N,N-ditetradecylhydroxylamine, N,N-dihexadecylhydroxylamine, N,N-dioctadecylhydroxylamine, N-hexadecyl-N-octadecylhy-droxylamine, N-heptadecyl-N-octadecylhydroxylamine, N,N-dialkylhydroxylamine derived from hydrogenated tallow amine.
5. Nitrones, for example, N-benzyl-alpha-phenyl-nitrone, N-ethyl-alpha-methyl-nitrone, N-oc-tyl-alpha-heptyl-nitrone, N-lauryl-alpha-undecyl-nitrone, N-tetradecyl-alpha-tridcyl-nitrone, N-hexadecyl-alpha-pentadecyl-nitrone, N-octadecyl-alpha-heptadecyl-nitrone, N-hexadecyl-alpha-heptadecyl-nitrone, N-ocatadecyl-alpha-pentadecyl-nitrone, N-heptadecyl-alpha-hep-tadecyl-nitrone, N-octadecyl-alpha-hexadecyl-nitrone, nitrone derived from N,N-dialkylhy-droxylamine derived from hydrogenated tallow amine.
6. Thiosynergists, for example, dilauryl thiodipropionate or distearyl thiodipropionate.
7. Basic co-stabilisers, for example, melamine, polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, urea derivatives, hydrazine derivatives, amines, polyamides, polyurethanes, alkali metal salts and alkaline earth metal salts of higher fatty acids for example calcium stearate, zinc stearate, magnesium behenate, magnesium stearate, sodium ricinoleate and potassium palmitate, antimony pyrocatecholate or zink pyrocatecholate.
8. Nucleating agents, for example, inorganic substances such as talcum, metal oxides such as titanium dioxide or magnesium oxide, phosphates, carbonates or sulfates of, preferably, alkaline earth metals; organic compounds such as mono- or polycarboxylic acids and the

salts thereof, e.g. 4-tert-butylbenzoic acid, adipic acid, diphenylacetic acid, sodium succinate or sodium benzoate; polymeric compounds such as ionic copolymers (ionomers).
9. Fillers and reinforcing agents, for example, calcium carbonate, silicates, glass fibres,
glass bulbs, asbestos, talc, kaolin, mica, barium sulfate, metal oxides and hydroxides, car¬
bon black, graphite, wood flour and flours or fibers of other natural products, synthetic fibers.
10. Other additives, for example, plasticisers, lubricants, emulsifiers, pigments, rheology additives, catalysts, flow-control agents, optical brighteners, flameproofing agents, antistatic agents and blowing agents.
11. Benzofuranones and Indolinones, for example those disclosed In U.S. 4,325,863; U.S. 4,338,244; U.S. 5,175,312; U.S. 5,216,052; U.S. 5,252,643; DE-A-4316611; DE-A-4316622; DE-A-4316876; EP-A-0589839 or EP-A-0591102 or 3-[4-(2-acetoxyethoxy)-phenyl]-5,7-di-tert-butyl-benzofuran-2-one, 5,7-dl-tert-butyl-3-[4-(2-stearoyloxyethoxy)phe-nyl]benzofuran-2-one, 3,3'-bis[5,7-dl-tert-butyl-3-(4-[2-hydroxyethoxy]phenyl)benzofuran-2-one], 5,7-dl-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one, 3-(4-acetoxy-3,5-dimethylphe-nyl)-5,7-dl-tert-butyl-benzofuran-2-one, 3-(3,5-dimethyl-4-plvaloyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one, 3-(3,4-dimethylphenyl)-5,7-dl-tert-butyl-benzofuran-2-one, 3-(2,3-di-methylphenyl)-5,7-di-tert-butyl-benzofuran-2-one.
Another subject of the Invention is a process for improving the color of an oligomer, cooligomer, polymer or copolymer or blends thereof, containing a stable free nitroxyl radical

by adding a reducing agent to said polymer and heating said mixture to above the glass temperature in case of amorphous polymers or above the melting point in case of crystalline or semi-crystalline polymers; with the proviso that essentially no polymerizable monomer Is present.
There are different reasons, why stable free nitroxyl radicals may be present in a polymer One possibility Is that graft polymers have been prepared in the presence of a nitroxyl radical or a nitroxyl ether. Such a process typically comprises a first step A), wherein a stable

nitroxyl radical is grafted onto a polymer, which step comprises heating a polymer and a compound containing a stable NO* radical to above the melting point of the polymer, mixing and reacting the components at said temperature; and in a second step B) the grafted polymer of step A) is heated in the presence of an ethylenically unsaturated monomer or oligomer to a temperature at which cleavage of the nitroxyl-polymer bond occurs.
Such polymers, grafted in the presence of a nitroxyl radical or a nitroxyl ether are also a preferred embodiment of the present invention.
The stable free nitroxyl radical may also be present in the polymer due to its admixture for monomer stabilization or due to its use as chain stopping agent.
Preferred is a process for improving the color of polymers, obtained by radical polymerization, which polymerization has been carried out in the presence of a stable free
nitroxyl radical and a source of free radicals capable of initiating the
polymerization, or in the presence of a nitroxyl ether , wherein
X represents a group having at least one carbon atom and is such that the free radical derived from X is capable of initiating polymerization and the remaining radical
forms a stable free nitroxyl radical;
by adding a reducing agent to said polymer and heating said mixture to above the glass
temperature In case of amorphous polymers or above the melting point in case of crystalline
or semi-crystalline polymers;
with the proviso that essentially no polymerizable monomer is present.
The process is preferably carried out, wherein the mixture is heated to 50°-150° C above the glass temperature in case of amorphous polymers or 20°-180° C above the melting point in case of crystalline or semi-crystalline polymers.

The heating step of the process may be performed in any reactor suitable for mixing a polymer melt. Preferably the reactor is an extruder or kneading apparatus as for example described in "Handbuch der Kunststoffextrusion" Vol.1, editor F. Hensen, W. Knappe and H. Potente, 1989, pages 3-7. If an extruder is used the process may be described as reactive extrusion process. Examples of reactiv extrusion equipment and processes are given by G. H. Hu et a!., in "Reactive Modifiers for Polymers", first edition, Blackie Academic & Professional an Imprint of Chapman & Hall, London 1997, chapter 1, pages 1-97.
Preferably, If an extruder is used, a reduced pressure of less than 200 mbar is applied during extrusion. Volatile by products may be removed thereby.
Typical reaction times are from a few seconds to several hours. Preferably the reaction time
is from 10 seconds to 1 h, most preferably from 20 seconds to 20 min.
Another subject is the use of a reducing agent for improving the color of an oligomer,
cooligomer, polymer or copolymer or blends thereof, containing a stable free nitroxyl radical
\ N-0- .
/
Still another subject of the invention is the use of a reducing agent for removing the discoloration of polymers, obtained by radical polymerization, which polymerization has been
carried out in the presence of a stable free nitroxyl radical and a source of free
radicals capable of initiating the polymerization, or in the presence of a nitroxyl ether , wherein
X represents a group having at least one carbon atom and is such that the free radical derived from X is capable of initiating polymerization and the remaining radical
forms a stable free nitroxyl radical.

The following examples illustrate the invention.
The nitroxyl compounds A, B and C used in the following examples are known and can be prepared by oxidation of the corresponding amines for example according to US 5,654,434, 5,204,473 and GB 2 335 190.
Example 1
Color improvement of polystyrene synthesized by controlled free radical polymerization in
presence of a nitroxyl radical
In a 2 I reactor 1.419 g (5.858 mmol) dibenzoyi peroxide and 2.707 g (7.615 mmol) dodecanoic acid-(2,2,6,6-tetramethyl-piperidine-4-yl-1-oxyl)ester (nitroxyl A) are added to 1590 g (15.27 mol) styrene under argon atmosphere. Dissolved oxygen is removed in re¬peating evacuation/Ar-purging steps. The reaction mixture is stirred and heated under argon atmosphere to 125° C for 6 hours. Remaining monomer is removed at 60° C under vacuum. The residue is dried in a first step under vacuum and in a second step under normal pressure at 70° C until constant weight is achieved (1390 g polystyrene, 87 % conversion). From the synthesized polystyrene a molded plaque of 2 mm thickness is prepared (molding conditions: 1 min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The yellowness index is measured according to DIN 53383.
In a twin screw extruder, model TW 100, Haake, the synthesized polystyrene is extruded together with the additives given in table 3 at a temperature T^ax - 220 °C (heating zones 1 - 5) and 40 r/min. The product is granulated from strands in a water bath. From the granules a molded plaque of 2 mm thickness is prepared (molding conditions: 1 min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The plaques are stored at 80° C in a circulating air drying oven in order to determine discoloration during thermal aging after definite time intervals. Table 1 shows the measured yellowness index at different time intervals (h).

Example 2-4
Color Improvement of polystyrene containing nitroxyl-radicals (model experiment)
In a twin screw extruder, model TW 100, Haake, a commercial general purpose polystyrene (PS-165/H ex BASF, MFR(200/5) - 2-9) is extruded together with 0.1% decandioic acid bis(2,2,6,6-tetramethyl-piperidine-4-yl-1-oxyl)ester (CXA 5415, commercial nitroxyl of Ciba Specialty Chemicals) at a temperature Tmax = 220 °C (heating zones 1 - 5) and 40 r/min. The product is granulated from strands in a water bath. From the granules a molded plaque of 2 mm thickness is prepared (molding conditions: 1 min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The yellowness index is measured according to DIN 53383.
The nitroxyl radical containing granulate is extruded for a second time together with the additives given in table 1 (Tmax =250 °C (heating zone 1 - 5) and 40 r/min), granules are formed and molded plaques are prepared as given above.
The plaques are stored at 80° C in a circulating air drying oven in order to determine discoloration during thermal aging after definite time intervals. Table 2 shows the measured yellowness index at different time intervals (h).

In a twin screw extruder, model ZSK 25, Werner & Pfleiderer, a commercial grade low density polyethylene (Lupolen 1812E ex BASF, MFR(190/21.6) = 34) is extruded together with 0.1% dodecanoic acid(2,2,6,6-tetramethyl-piperidine-4-yl-1-oxyl)ester at a temperature Tmax ~ 200 °C (heating zones 1 - 5) and 100 r/min. The product is granulated from strands in a water bath. From the granules a molded plaque of 2 mm thickness is prepared (molding conditions: 1 min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The yellowness index is measured according to DIN 53383.
The nitroxyl radical containing granulate is extruded for a second time together with the additives given in table 1 (Tmax = 220 °C (heating zone 1 - 5) and 100 r/min), granules are formed and molded plaques are prepared as given above. Table 3 shows the measured yellowness index.
Table 3: yellowness index of molded polyethylene

Example 9-13
Color improvement of polystyrene containing nitroxyl-radicals (model experiment)
In a twin screw extruder, model ZSK 25, Werner & Pfleiderer, a commercial general purpose polystyrene (PS-165/H ex BASF, MFR(200/5) = 2.9) is extruded together with 0.05% octadecanoic acid(2,2,6,6-tetramethyl-piperidine-4-yl-1-oxyl)ester at a temperature Tmax -220 "C (heating zones 1-5) and 100 r/min. The product is granulated from strands in a water bath. From the granules a molded plaque of 2 mm thickness is prepared (molding conditions: 1 min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The yellowness index is measured on a Minolta CM 3600D according to DIN 6167. The nitroxyl radical containing granulate is extruded for a second time together with the additives given in Table 4 (Tmmx = 220 "C (heating zone 1 - 5) and 100 r/min), granules are formed and molded plaques are prepared as given above. Table 4 shows the measured yellowness index.
Table 4: yellowness index of molded polystyrene

Example 14-20
Color improvement of polystyrene containing nitroxyl-radicals (model experiment)
In a twin screw extruder, model ZSK 25, Werner & Pfleiderer, a commercial general purpose polystyrene (PS-165/H ex BASF, MFR(200/5) = 3.5) is extruded together with 0.05% acetic acid(2,6-diethyl-2,3,6-trimethyl-piperidine-4-yl-1-oxyl)ester at a temperature Tmax = 220 °C (heating zones 1 - 5) and 100 r/min. The product is granulated from strands in a water bath. From the granules a molded plaque of 2 mm thickness is prepared (molding conditions: 1

min heating, 1 min molding, 1 min pressure release, 3 min molding, T = 220° C). The yellowness index is measured on a Minolta CM 3600D according to DIN 6167.
The nitroxyl radical containing granulate is extruded for a second time together with the additives given in table 4 (Tmax = 220 X (heating zone 1 - 5) and 100 r/min), granules are formed and molded plaques are prepared as given above. Table 5 shows the measured yellowness index.

Irgafos P-EPQ = tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]4,4'-diylbisphosphonite
(commercial product of Ciba Specialty Chemicals)
Irgafos TNPP =tns(nonyl-phenyl)phosphite (commercial product of Ciba Specialty
Chemicals)
Irgafos 126 = bis(2,4-di-tert-butylphenyl)pentaerythrol-diphosphite (commercial product of
Ciba Specialty Chemicals)

WE CLAIM:
1. A composition for improving the colour of polymers comprising,
a) at least one oligomer, cooligomer, polymer or copolymer or blends
thereof, obtainable by radical polymerization or by grafting, which
polymerization or grafting has been carried out in the presence of a
stable free nitroxyl radical and a source of free radicals capable
of initiating the polymerization, or in the presence of a. nitroxyl ether
wherein X represents a group having at least one carbon atom and is such that the free radical derived from X is capable of initiating
polymerization and the remaining radical forms a stable free
nifroxyl radical; and
b) a reducing agent, which is selected from the group consisting of a cyclic
ethylenically unsaturated compound having an allylic hydrogen atom,
H3PO2 (phosphinic acid), H4P2O4 (hypodiphosphonic acid),
H5PO3/H4P2O5 (phosphonic-/diphosphonic acid), H4P2O6
(hypodiphosphoric acid), H2S2O2/H2S2O3 (sulfoxylic-Zthiosulftiric acid),
H2S2O4 (dithionic acid), H2SO3/H2S2O5 (sulfurous-Zdisulfiirous acid), R-
S-OH (sulfenic acid) or R-S=0-OH (sulfinic acid) or and their
ammonium, alkali metal or alkali earth metal salts; or a mixture of said
reducing agents; with the proviso that the composition is essentially free
of a polymerizable monomer.

2. The composition according to claim 1, wherein the reducing agent is a mixture of a cycilc ethylenically unsaturated compound having an allyhc hydrogen atom and a phosphorous compound according to claim 1 or a mixture of a cyclic ethylenically unsaturated compound having an allylic hydrogen atom and a sulfur compound according to claim 1.
3. The composition according to claim 1, wherein the reducing agent is H3PO2 (phosphinic acid), or a Na, K, Ca, Mg or ammonium salt thereof, with or without crystal water.
4. The composition according to claim 1, wherein the reducing agent is a cyclic mono-, sesqui- or di-terpene having an allylic hydrogen atom.
5. The composition according to claim 1, wherein the reducing agent is y-terpinene or a-phellandrene.
6. The composition according to claim 1, wherein the reducing agent is present in an amount of 0.01% to 5% based on the weight of the polymer.
7. A process for improving the color of polymers, obtainable by radical polymerization or grafting, which polymerization or grafting has been carried
out in the presence of a stable free nitroxyl radical and a source of
free radicals capable of initiating the polymerization, or in the presence of a
nitroxyl ether , wherein X represents a group having at least one
carbon atom and is such that the free radical derived from X is capable of
-41-

initiating polymerization and the remaining ' radical forms a stable free
nitroxyl radical; by adding a reducing agent according to claim 1 to said polymer and heating said mixture to above the glass temperature in case of amorphous polymers or above the melting point in case of crystalline or semi-crystalline polymers; with the proviso that essentially no polymerizable monomer is present.
8. The process according to claim 7, wherein the mixture is heated to 50°-150°C above the glass temperature in case of amorphous polymers or 20°-180°C above the melting point in case of crystalline or semi-crystalline polymers.

Documents:

in-pct-2002-0967-che abstract.pdf

in-pct-2002-0967-che claims duplicate.pdf

in-pct-2002-0967-che claims.pdf

in-pct-2002-0967-che correspondence-others.pdf

in-pct-2002-0967-che correspondence-po.pdf

in-pct-2002-0967-che description (complete) duplicate.pdf

in-pct-2002-0967-che description (complete).pdf

in-pct-2002-0967-che form-1.pdf

in-pct-2002-0967-che form-19.pdf

in-pct-2002-0967-che form-26.pdf

in-pct-2002-0967-che form-3.tif

in-pct-2002-0967-che form-4.pdf

in-pct-2002-0967-che form-5.pdf

in-pct-2002-0967-che pct search report.pdf

in-pct-2002-0967-che pct.pdf

in-pct-2002-0967-che petition.pdf

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Patent Number

201828

Indian Patent Application Number

IN/PCT/2002/967/CHE

PG Journal Number

08/2007

Publication Date

23-Feb-2007

Grant Date

10-Aug-2006

Date of Filing

24-Jun-2002

Name of Patentee

M/S. CIBA SPECIALTY CHEMICALS HOLDING INC

Applicant Address

KLYBECKSTRASSE 141, CH-4002 BASEL,

Inventors:

#	Inventor's Name	Inventor's Address
1	PFAENDNER, RUDOLF	SACKGASSE 3, 64668 RIMBACH
2	ROTH, MICHAEL	FALTORWEG 5, 64686 LAUTERTAL
3	WUNDERLICH, WIEBKE	VIA VALDOSSOLA 28, 40134 BOLOGNA

PCT International Classification Number

C08K5/3435

PCT International Application Number

PCT/EP00/11378

PCT International Filing date

2000-11-16

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	99811089	1998-11-25	EUROPEAN UNION