Title of Invention

A PROCESS FOR PREPARING A THERMOPLASTIC VULCANIZATE COMPOSITION

Abstract

A process for preparing a thermoplastic vulcanizate comprising dynamically vulcanizing a blend of a) an engineering thermoplastic selected from the group consisting of polyester, polycarbonate, polyester block copolymer or combinations thereo having a melting point of at least 170°C and below 260°C and a weight average molecular weight above 40.000. b) from 200 to 375 parts by weight of carboxylated nitrile rubber per 100 parts by weight of said thermoplastic. c) from 1 to 12 parts by weight of an addition type curing agent per 100 parts by weight of said rubber and d) from 3 to 30 parts by weight per 100 parts by weight of said thermoplastic of a processing aid selected from the group consisting of functionalized polyolefins derived from C2-8 monomers, functionalized polyolefins derived from C2-8 monomers copolymerized with C3-10 unsaturated acids, ethylene vinyl alcohol copolymers, ethylene vinyl acetate copolymers, functionalized ethylene-propylene copolymers, functionalized ethylene-propylene-diene copolymers, functionalized styrenic block copolymers or combinations thereof.

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970] COMPLETE SPECIFICATION [See Section 10] Rule 13 A PROCESS FOR PREPARING A THERMOPLASTIC VOLCANIZATE COMPOSITION ADVANCED ELASTOMER SYSTEMS, L.P., a limited partnership, duly organized and existing under the laws of the State of Delaware, with a principal place of business at 388 South Main Street, Akron, Ohio 44311-1059, United States of America, The following specification particularly describes the nature of the invention and the manner in which it is to be performed:- GRANTED 726/MUM/2000 -3 AUG 200024-10-2005 The present invention relates to a process for preparing a thermoplastic vulcanizate composition. This application is a continuation-in-part of U.S. Serial /Number 08/987,961, filed on Dec. 10, 1997. FIELD OF INVENTION The present invention' relates to thermoplastic vulcanizates (TPVs) containing thermoplastic polyurethane and small particles of cured nitrile rubber dispersed therein. The present invention further contains ad¬dition type curing aids, which enhance processability and will not affect or breakdown the thermoplastic phase. BACKGROUND OF THE INVENTION Heretofore, many types of thermoplastic vulcanizates were known. More specifically, U.S. Patent No. 4,226,953 to Coran and Patel relates to thermoplastic compositions comprising blends of styrene-acrylonitrile (SAN) resin and nitrile rubber of high gel content. U.S. Patent No. 4,141,863,to Coran et al. relates to a thermo¬plastic composition comprising blends of cross-linked rubber and thermo¬plastic linear crystalline polyester using thermoplastic polyesters having a softening point above 50°C. Rubbers include natural or synthetic diene rubber polyurethane rubber and nitrile rubber. The blends . may also contain plasticizers. U.S. Patent 4,666,972 relates to polyalkylene terephthalates which contain a fluorinated polyolefin in addition to a polymer having a glass transition temperature of less than -30°C. U.S. Patent No. 5,397,839 relates to elastomeric composition's having improved heat aging properties provided by blends of thermoplastic polyester resin and hydrogenated nitrile rubber. The rubber component of. the composition is at least partially cured-. U.S. Patent No. 5,550,190 to Hasegawa et al: relates to a thermoplastic elastomer composition obtained by dynamically crosslinking (A) 51-95% by weight of a thermoplastic polyester-ether elastomer and (B) 49-5% by weight of a rubber during kneading. U.S. Patent No. 5,637,407 to Hert et al. relates to a composite including a rubber/thermoplastic blend adherent by itself to a thermoplastic material; the blend is in the form of a thermoplastic matrix containing rub¬ber nodules functiohalized and vulcanized during the mixing with the ther¬moplastic. Composite articles are obtained by overmoulding the vulcan¬ized rubber/thermoplastic blend onto the thermoplastic. U.S. Patent No. 5,376,723 to Vogt et al. relates to a thermo¬plastic polymer blend of polyurethane and nitrile rubber having a Shore A hardness of about 55 to 70. The thermoplastic polyurethane component includes at least about 50 weight percent (wt. %) polyisocyanate; the ni¬trile rubber component includes about 34 mole percent (mol.%) acryloni-trile; and, the ratio between the thermoplastic polyurethane component and the nitrile rubber component is about 30:70 to.40:60 volume percent¬age (vol. %). A peroxide crosslinking agent for the nitrile rubber may be mixed into the TPU/nitrile rubber blend. According to the present invention there is provided a process for preparing a thermoplastic vulcanizate comprising dynamically vulcanizing a blend of a) an engineering thermoplastic selected from the group consisting of polyester, polycarbonate, polyester block copolymer or combinations thereof, having a melting point of at least 170°C and below 260°C and a weight average molecular weight above 40.000." b) from 200 to 375 parts by weight of carboxylated nitrile rubber per 100 parts by weight of said thermoplastic. c) from 1 to 12 parts by weight of an addition type curing agent per 100 parts by weight of said rubber and d) from 3 to 30 parts by weight per 100 parts by weight of said thermoplastic of a processing aid selected from the group consisting of functionalized polyolefins derived from C2-8 monomers, functionalized polyolefins derived from C2-8 monomers copolymerized with C3-10 unsaturated acids, ethylene vinyl alcohol copolymers, ethylene vinyl acetate copolymers, functionalized ethylene-propylene copolymers, functionalized ethylene-propylene-diene copolymers, functionalized styrenic block copolymers or combinations thereof. SUMMARY OF INVENTION The thermoplastic vulcanizate compositions (TPV) of the present invention provide advantages over the currently available TPVs by offering improved meit processability by providing product melt phase degassing, improved processability due to the decreased tendency of the product melt to ad¬here to metal, improved physical properties using the curatives of this in¬vention, and increased upper service temperatures; Generally, the TPVs of polymers is desirably at least 170°C, desirably at least 200°C and pref¬erably at least 220°C. Excessively high melt temperatures are avoided inasmuch as during melt mixing of the thermoplastic with the carboxy-lated nitrile rubber, the high melt temperature will degrade the nitrile rub¬ber. Accordingly, the thermoplastic generally has a high melting point below 2'60°C, and more desirably below 240°C. Suitable thermoplastic polymers include polyesters, polycarbonates, block copolymers of polyes¬ter, and the like. Polyesters are condensation polymers. The various polyesters can be either aromatic or aliphatic or combinations thereof and are gener¬ally directly or indirectly derived from the reactions of diols such as glycols having a total of from 2 to 6 carbon atoms and desirably from about 2 to about 4 carbon atoms with aliphatic acids having a total of from about 2 to about 20 carbon atoms and desirably from about 3 to about 15 carbon atoms or aromatic acids having a total of from about 8 to about 15 carbon atoms. Generally, aromatic polyesters are preferred such as polyethyl-eneterephthalate (PET), polytrimethyleneterephthalate (PTT), polybuty-leneterephthalate (PBT), polyethyleneisophthalate, and polybutylenenap-thalate. Various polycarbonates can also be utilized and the same are es¬ters of carbonic acid. A suitable polycarbonate is that based on bisphenol A, e.g., poly(carbonyldioxy-1,4-phenyleneisopropylidene-1,4-phenylene). Suitable polyester block copolymers include segmented polyes-ter-polyether and the like. These block copolymers contain at least one block of a polyester and at least one rubbery block such as a polyether derived from glycols having from 2 to 6 carbon atoms, e.g., polyethylene glycol, or from alkylene oxides having from 2 to 6 carbon atoms. A pre¬ferred block polyester-polyether polymer is polybuty-leneterephthalate-b-polytetramethylene glycol which is available as Hytrel from DuPont. The molecular weight of the various thermoplastic resins is such that it is a suitable engineering plastic. Accordingly, the weight av¬erages molecular weight of the various polyesters generally range from about 40.000 to above 110.000 with from about 50,000 to about 100,000 being preferred. The rubber phase of the thermoplastic vulcanizate composition of the present invention comprises carboxylated nitrile rubber. Such rub¬ber desirably has a small particle size below 50 microns and preferably from about 1 to 10 microns to yield good physical properties and process¬ing characteristics. Nitrile rubbers are generally derived from conjugated dienes having from 4 to 8 carbon atons with isoprene being desired and butadiene being preferred, and from acrylonitrile. The amount of the con¬jugated diene content within the copolymer is generally a majority, that is, from about 50 to about 80 percent by weight, and desirably from about 60 to about 75 percent by weight. The acrylonitrile content of the co-polymer is thus the corresponding minority amount, i.e., from about 20 percent to about 50 percent by weight and preferably from about 25 to about 40 percent by weight. The actual amount of acrylonitrile will vary depending upon end use application since increased amounts of acryloni¬trile improve oil resistance, tensile strength, hardness and abrasion resis¬tance. However, increased amounts of acrylonitrile in nitrile rubber will adversely affect the low temperature properties. The nitrile rubbers utilized in the present invention contain pen¬dant carboxyl groups thereon such as those derived from unsaturated ac¬ids, for example, acrylic add, methacrylic acid, and the like. The amount of carboxylic acid monomer copolymerized in the nitrile rubber is generally from about 1 to about 10 parts by weight and preferably from about 3 to about 7 parts by weight based upon 100 parts by weight of the nitrile rubber derived from acrylonitrile and the conjugated diene monomers. Upon cure, the carboxylated nitrile rubber can be cross-linked via the un-saturation present in the copolymer, or alternatively via the pendent car- boxylic acid groups. The amount of the nitrile rubber utilized in the present invention generally ranges from about 50 to about 400 parts by weight, desirably from about 200 to about 375 parts by weight, and preferably from about 230 to about 360 parts by weight for every 100 parts by weight of the one or more thermoplastic polymers. Heretofore, polar thermoplastic vulcanizate compositions containing carboxylated nitrile rubber in absence of a processing aid gen¬erally formed a powder during processing, such as at a 1 to 3 plastic to rubber ratio. It has now been unexpectedly found that when a processing aid is added to the composition during mixing and before curing, substan¬tial improvement in processability results. For example, powder formation is prevented and the product obtained is a processable thermoplastic ma¬terial. It is also noted that bisoxazoline grafting of the plastic polymer onto the rubber via the end groups of the plastic and the carboxylic acid cure sites in the rubber may occur during TPV formation. This compatibi-lizing agent that can be formed in situ would also contribute to TPV me¬chanical properties. The processing aids, which further act as a bulk compatibiliz-ing agent, is generally a hydrocarbon polymer and optionally but preferably such polymers which have functional groups thereon, e.g., preferably pen¬dant therefrom. Such hydrocarbon polymers include polyolefins derived from C2 to C8 monomers such as polyethylene or polypropylene. Another class of processing aids is the various copolymers of olefins with an un¬saturated acid having a total of from 3 to about 10 carbon atoms such as maleic acid, acrylic acid, and the like with a suitable copolymer being poly(ethylene-acrylic acid). Ethylene-vinyl alcohol or ethylene vinyl acetate copolymers and the like are also suitable processing aids. Still another class of processing aids are various hydrocarbon based rubbers such as ethylene-propylene copolymers, ethylene-propylene-diene copolymers (i.e., EPDM), and the like. A still further class are various hydrocarbon block copolymers such as styrene-butadiene-styrene (e.g., the various Kraton® grades manufactured by Shell), styrene-ethylene-butene-styrene block co¬polymers, and the like. The functional group of the processing aid can generally in¬clude any group which can react with the polar group of the thermoplastic resin, or the carboxylated nitrile rubber, or the curatives set forth herein below. Such functional groups include hydroxyl groups, as in an ethylene-vinyl alcohol copolymer, with acid groups or anhydride groups being pre-- ferred. The acid groups are generally obtained from unsaturated acids having from 3 to 10 carbon atoms such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and the like. The anhydrides include the various anhydrides of the above acids with maleic anhydride being preferred. The amount of the entire functional compound is generally from about 0.2 to about 6 or 10 percent by weight of the total weight of the above-noted processing aids. Preferred processing aids which also act as compatibilizing aids include maleated polyethylene, maleated polypropylene, an ethylene-acrylic acid copolymer, maleated styrene-ethylene-butene-styrene-block copoly¬mers, maleated styrene-butadiene-styrene block copolymers, maleated ethylene-propylene rubber, blends and cured blends of polypropylene or polyethylene and EPDM rubber (e.g., Santoprene® having a hardness of from about 35 Shore A to about 50 Shore D), and the like. Maleated polyethylene, maleated ethylene-propylene rubber and maleated styrene-butadiene-styrene block copolymers are highly preferred. The amount of the processing and/or compatibilizing aids gener¬ally range from about 3 parts to about 30 parts by weight and preferably from about 5 parts to about 20 parts by weight based upon 100 parts by weight of the thermoplastic resin. The utilization of the processing aids with the carboxyl contain- ing nitrile rubbers results, after dynamic vulcanization, in the formation of a highly compatible blend wherein the thermoplastic or thermoplastic elas¬tomer generally constitutes a continuous phase and the rubber particles constitute a discontinuous phase. However, other possible morphologies may exist. Another important aspect of the present invention is the utiliza¬tion of addition type curatives which, do not break down the plastic phase and do not form volatile compounds such as water. While other curing agents can be utilized such as free radical generating compounds, the same are not desired and thus used in small amounts such as generally less than 1.0 parts by weight and desirably less than 0.5 parts by weight based upon 100 parts by weight of the carboxylated nitrile rubber. A highly preferred addition curative or cross-linking agent is the various oxa-zolines or oxazines such as those having the formula wherein R or R' is an aliphatic or aromatic hydrocarbon group such as al- kylene or arylene having 1 to 24 carbon atoms optionally substituted with one or more alkyl groups having 1 to 6 carbon atoms or substituted with an aryl group having 6 to 9 carbon atoms; n is 0 or 1, when n equals 1 then X and Y are hydrogen atoms or independently an 2-oxazoline group or a 1,3-oxazine group, or a 2-oxazoline group or a 1,3-oxazine group and a hydrogen atom, with the remaining carbon atoms having hydrogen at¬oms thereon, p and q, independently, is 1 or 2, and when n equals 0 then R, X , and Y are nonexistent. Further, each oxazoline group of the above formula may optionally be substituted with an alkyl of 1 to 6 carbon at¬oms. Further descriptions of said polyvalent oxazolines are set forth in U.S. Patent 4,806,588, herein incorporated by reference. Preferred oxa¬zolines include 2,2'-bis(oxazoline-2), 2,2'hexamethylenedicarbamoylbis(oxazoline-2), and 1,3-phenylene-2,2'bis(oxazoline-2). Various bismaleimides .as well as phenolic resins can also be used as curatives. Examples of bismaleimides include a bismaleimide based on methylene dianiline (e.g., Matrimid 5292A from Ciba-Geigy), a bismaleimide based on toluene diamine (e.g., HVA-2 from DuPont), and the like. The phenolic curing agents are well known to the art and litera¬ture and include polymers obtained by the polymerization of phenol with formaldehyde. The polymerization rate is pH dependent, with the highest reaction rates occurring at both high and low pH. A more detailed descrip¬tion of the preparation of phenolic resins is set forth in "Principles of Po¬lymerization" 3rd Edition, George Odian, pages 125-131, John Wiley Sons, Inc., N.Y., N.Y., 1991, which is hereby fully incorporated by reference. Examples of specific phenolic resins include such as SP-1045 where R is isooctyl and n is 1 to 1 2, and HRJ-1367 where R is t-butyl and n is from 1 to 10, from Schenectedy Chemicals. Other addition type curatives can be utilized including various isocyanates such as 1,4-phenylenediisocyanate, isophorone diisocyanate, and a, co-isocyanate terminated polymers; various carbodiimides such as poly(triisopropylphenylene carbodiimide) i.e., Stabaxol-P from Rhein Che-mie, and the like, as well as various bisimidazolines. The multifunctional imidazolines have the formula where R and n are defined as above for the multifunctional (polyvalent) oxazolines and X and Y, are a hydrogen atom, or, independently, an imida¬zoline group, or an imadazoline group and an hydrogen atom. A preferred multifunctional imidazoline is bismidazoline. Still another group of addition type curatives are the various mul¬tifunctional epoxides such as the various Shell Epon® resins, epoxidized vegetable oils, tris(2,3-epoxypropyl) isocyanate, and 4,4'-methylene bis(N,N-diglycidylaniline), and multifunctional aziridines. The amount of the curative is generally from about 1 to 12, de¬sirably from 2 to 10, and preferably from about 2.5 to about 7 parts by weight for every 100 parts by weight of the carboxylated nitrile rubber. The addition curatives effect cross-linking by reacting with the carboxylic acid groups present in the nitrile rubber or double bonds of the diene hy¬drocarbon portion derived from the diene monomer. The amount of cura¬tives used results in at least a partially cured nitrile rubber and preferably a fully or completely vulcanized nitrile rubber. The terms "fully vulcanized" and "completely vulcanized" as used in the specification and claims means that the rubber component to be vulcanized has been cured to a state in which the elastomeric proper¬ties of the cross-linked rubber are similar to those of the rubber in its con¬ventional vulcanized state, apart from the thermoplastic vulcanizate com¬position, or as indicated by no more change in tensile strength. The de¬gree of cure can be described in terms of gel content or, conversely, ex-tractable components. Alternatively, the degree of cure may be expressed in terms of cross-link density. All of these descriptions are well known in the art, for example, in U.S Patent Nos. 5,100,947 and 5,157,081, both of which are fully incorporated herein by this refererTcer—Bythe term "par¬tially vulcanized" (i.e., degree of cure), it is meant that about 30 percent or less and desirably about 10 percent or less by weight of a carboxylated nitrile rubber is soluble in methyl ethyl ketone at 80°C. By the term "fully vulcanized" (i.e., degree of cure), it is meant that about 5 percent or less of the cured carboxylated nitrile rubber is soluble in a methyl ethyl ketone at 80°C. In addition to the thermoplastic resin, nitrile rubber, the proc¬essing aid, and the curative, the compositions of the present invention can include various conventional additives such as reinforcing and non-reinforcing fillers, extenders, antioxidants, stabilizers, rubber processing oil, extender oils, lubricants, plasticizers, anti-blocking agents, anti-static agents, waxes, foaming agents, pigments, flame retardants and other processing aids known in the rubber compounding art. Such additives can comprise up to about 60 weight percent of the total composition, and can be in the plastic phase, the rubber phase or both. Fillers and extenders which can be utilized include conventional inorganics such as calcium car¬bonate, clays, silica, talc, titanium dioxide, carbon black, and the like. The rubber processing oils generally are paraffinic, naphthenic or aromatic oils derived from petroleum fractions. The type will be that ordinarily used in conjunction with the specific rubber or rubbers present in the composi¬tions, and the quantity based on the total rubber content may range from zero to about 100 phr and preferably from about 10 to about 40 phr. Partial or preferably complete cross-linking can be achieved by adding one or more of the above-noted rubber curatives to the blend of a thermoplastic or the thermoplastic elastomer and rubber and vulcanizing the rubber to the desired degree under conventional vulcanlzlHcfconditions. However, it is preferred that the rubber be cross-linked by the process of dynamic vulcanization. As used in the specification and claims, the term "dynamic vulcanization" means a vulcanization or curing process for a rubber contained in a thermoplastic vulcanizate composition, wherein the rubber is vulcanized under conditions of shear at a temperature above the melting point of the polyester component. The rubber is thus simultane¬ously cross-linked and dispersed as fine particles within the polyester ma¬trix, although as noted above, other morphologies may also exist. Dy¬namic vulcanization is effected by mixing the thermoplastic vulcanizate components at elevated temperature in conventional mixing equipment such as roll mills, Banbury mixers, Brabender mixers, continuous mixers, mixing extruders, and the like. The unique characteristic of dynamically cured compositions is that, notwithstanding the fact that the rubber com¬ponent is partially or fully cured, the compositions can be processed and reprocessed by conventional plastic processing techniques such as extru¬sion, injection molding, blow molding and compression molding. Scrap or flashing can be salvaged and reprocessed. The following general procedure was used in the preparation of thermoplastic vulcanizates of the present invention as set forth in the examples. Thermoplastic polyester, nitrile rubber, and the processing aids were mixed in a Brabender mixer at a temperature sufficient to melt the thermoplastic and form a blend. Curatives were then added to cross¬link the rubber and mixing was continued until a maximum melt consis¬tency was reached, usually between one and five minutes, then for an additional two to three minutes thereafter. The sequence of ingredient addition may vary, but generally all of the fillers should be added before substantial cross-linking, or vulcanization occurs. The stabilizers and plasticizers may be added either before or after vulcanization. The vul¬canized composition was removed from the mixer, sheeted, and com¬pression molded at 30° to 50°C above the melting point of the thermo¬plastic component, and cooled below 100°C under pressure. Properties of the molded sheet were then measured. The thermoplastic vulcanizate compositions of the present in¬vention generally have good tensile strength, good elongation and good compression set properties. Most notably, they have very low oil swell, i.e., excellent oil resistance properties comparable to that of the thermo-set nitrile rubber. Oil swell values as measured by the percent of weight gain at 150°C for 72 hours is generally 25 percent or less, desirably 20 percent or less, and preferably 15 percent or less. The thermoplastic vulcanizate compositions of the present invention can be used in applications wherever nitrile rubber is used. Thus they can be utilized as seels, as gaskets, hoses, boots, and the like, espe¬cially for automotive applications. The invention will be better understood by reference to the following examples which serve to illustrate, but not to limit, the present invention. Thermoplastic vulcanizates (TPVs) were produced in a labora¬tory Brabender-Plasticorder, model EPL-V5502. The mixing bowl had a capacity of 60 ml with roller type rotors, which gave good mixing for samples with a batch weight of 40-45 grams. For higher batch weight TPVs, less bulky cam rotors were used, which gave a bowl capacity of 85 ml. TPVs were prepared at 240°C and at 75-rpm rotor speed, unless in¬dicated otherwise. The plastic materials were melted or partially melted in the mixer cavity prior to rubber addition. After a steady torque was ob¬tained for 1 to 2 minutes in order to ensure as complete a homogenization as possible of the rubber and plastic melt blend, the curative was added and curing continued for about 8 minutes. The torque rise observed on curing leveled off after about 4 to 5 minutes into the cure. The TPV ob¬tained was sheeted when hot in a cold press, and subsequently compres¬sion molded at 250°C in order to produce plaques for physical testing. Plasticizers were added to the rubber and plastic melt blended prior to cure. When melt blending the plastic and rubber materials, it is important to at least partially melt the plastic prior to rubber addition. Masticating the rubber alone in the mixer will lead to thermooxidative crosslinking of the rubber which results in powdering of the rubber. Utilizing the above general procedure, specific recipes as set forth in Tables 1-4 were formulated and prepared. \ TABLE III Example I T7 I 18 I T9 Composition Nipol 1072 x 28 76 76 69.00 Irganox B225 3.17 ~ ~ 75PBT/25PBI 24 ~ ~ PET 13339 ~- 24 ~ Hytrel 8238 ~ ~ 31.00 Polybond 3009 2.38 2.38 2.37 1,3-PBO 2.38 140 3.04 Properties Hardness (Shore A) 79 82 85 UTS (psi) 1911 1566 2630 UE (%) 253 161 242 M 100 (PSI) 773 1052 1144 CS (%, 22 hr, 100°C) 20 14 25 CS (%, 22 hr, 150°C) 40 26 40 Wt. Gain {%, 72 hr, 150°C) 19 20 .. Tension Set (%) 7 11 12 Consistency of Product T . T T T: Thermoplastic Elastomeric Materials: Nipol 1072 X 28: Carboxylic acid functional nitrile rubber. Bound acrylonitrile ~ 27 weight percent. Carboxylic acid content: ~ 0.08 equivalents per hundred parts of rubber. Gel content: 50-60 weight per¬cent in methyl ethyl ketone (Zeon Chemicals, Inc., Louisville, KY.). Nipol DN3635: Gel free nitrile rubber. Bound acrylonitrile: 36 weight percent (Zeon Chemicals, Inc., Louisville, KY.). Chemigum HR 665: Nitrile rubber with bound antioxidant and 34 weight percent bound acrylonitrile (Goodyear Tire and Rubber Company, Akron, Ohio). Plastic Materials: Valox 315: Polyftetramethylene terephthalate) with weight average mo¬lecular weight of about 105,000, and number average molecular weight of about 50,000 (GE Plastics, Pittsfield, Massachusetts). 75PBT/25PBi: 75:25 weight percent poly(butylene terephtha- late/isophthalate) experimental polymer (AMOCO Chemicals, Naperville, Il¬linois). PET 13339: Modified polyethylene terephthalate), m.p. 235°C (Eastman Chemical Company, Kingsport, Tennessee). Hytrel 8238: Polyester-ether segmented block copolymer thermoplastic elastomer with 82 Shore D hardness (DuPont Company, Wilmington, Delaware). Processing Aids: Royaltuf 490: Maleated EPDM rubber with 1 weight percent bound maleic anhydride (Uniroyal Chemical Company, Middlebury, Connecticut). Kraton FG-1901X: Maleated styrene/ethylene-butene/styrene triblock co¬polymer with 2 weight percent bound maleic anhydride (Shell Chemical Company, Houston, Texas). Polybond 3009: Maleated high-density polyethylene with 1 weight per¬cent bound maleic anhydride (Uniroyal Chemical Company, Middlebury, Connecticut). HD 6706.19: High-density polyethylene (Exxon Chemical Company, Houston, Texas). Crosslinking Compounds: 1,3-PBO: 1,3-phenylenebis2,2'-(oxazoline-2) (Tramaco Japan Ltd., Tokyo, Japan). SP-1045: Alkylated phenol/formaldehyde resin (Schenectady Interna¬tional,, Inc., Schenectady, New York). HVA-2: 2,4-bismaleimidotoluene (DuPont Dow Elastomers, Stow, Ohio). Matrimid 5292A: Bis (4-maleimidophenyl) methane (Ciba-Geigy Corpora¬tion, Brewster, New York). TPAP: Trimethylolpropane tris(2-methyl-1-aziridenepropionate) (Aldrich Chemical Company, Milwaukee, Wisconsin). Plasticizers: Reofos 50: Isopropylated triphenyl phosphate (C.P. Hall Company, Stow, Ohio). Uniplex 809: Polyethylene glycol bis (2-ethylhexanoate) (Unitex Corpora¬tion, Greensboro, North Carolina). Uniplex 413: Substituted benzenesulfonamide (Unitex Corporation, Greensboro, North Carolina). Plasthall BSA: N-n-butylblenzenesulfonamide (C. P. Hall Company, Stow, Ohio). Paraplex G-30: Mixed dibasic acid polyester (C. P. Hall Company, Stow, Ohio). Remarc P-40-60: Chlorinated paraffinic oil with 39 weight percent chlo¬rine (Harwick Chemical Corporation, Akron, Ohio). Calsol 8450; 5120: Napthenic process oil (Sun Company, Canton, Ohio). Flexon 885: Paraffinic process oil (Exxon Oil Company, Houston, Texas). Antioxidant: Irganox B225: Phenolic/Phosphite based antioxidant (Ciba Specialty Chemicals Corporation, Troy, Michigan). Example 1 describes the preparation of a thermoplastic blend of carboxylated nitrile rubber and poly(butylene terephthalate). EXAMPLES: Table I illustrates the effects of processing aids on cured compositions of carboxylated nitrile rubber and PBT. On curing the blend of Example 1 with phenolic resin, a sticky and powdery product was isolated (Example 2) The compression molded plaque of this powdery product, however, exhibited good me¬chanical properties. In Example 3, the addition of maleated high-density polyethylene (Polybond 3009) to the recipe of Example 2 yielded a TPV that did not powder and could be easily removed from the mixer. It should be noted that the mechanical properties of the TPVs are considera¬bly better than that of the uncured blend of Example 1. Attempted TPV preparation from a blend of carboxylated ni¬trile rubber and poly(butylene terephthalate) with the use of 1,3-phenylenebis-2,2'(oxazoline-2) as a curative also yielded a sticky and powdery product (Example 4) in the absence of a process aid. The use of a process aid along with the oxazoline curative allowed the production of a thermoplastic product that could be readily removed from the mixer cavity (Example 5). Example 6 illustrates the preparation of a TPV with a re¬duced amount of process aid when compared to the amount used in Ex¬ample 5. In general, the lower the plastic content in a TPV recipe, the greater the chances of the production of an unprocessable product. The use of Polybond 3009 allows the preparation of a processable TPV unit with extremely low plastic to rubber ratio (20:80, Example 7). Examples 8-10 demonstrate the production of processable TPVs based upon carboxylated nitrile rubber, poly(butylene terephthalate),-and a maleated high-density polyethylene process aid, with maleimide and aziridine curatives-Table II illustrates the use of different processing aids. In Example 11, a melt blend of Nipol 1072 x 28 and Valox 31 5 (75:25 rubber to plastic weight ratio) was produced at 240°C and 75 rpm cam rotor speed. After adding the 1,3-PBO curative, the rotor speed was increased to 200 rpm and curing was continued at this speed for 9 minutes. During the cure, shear heating caused the material temperature to rise to 296°C. A "crumbly" product that stuck to the mixer cavity was the result. The procedure of Example 11 was repeated where part of the plastic phase (Valox 315) was replaced either with high-density polyethyl¬ene or maleated high-density polyethylene (Examples 12 and 13). In both cases, the material obtained was cleanly removed from the mixer and only slightly more "crumbly" when compared with the corresponding experi¬ments where the curing was conducted at 75 rpm. These examples illus¬trate further the importance of a process aid in the production of the thermoplastic TPVs of this invention. Examples 14, 15, and 16 document the properties of proc-essable TPVs obtained with the aid of a maleated styrene/ethylene bu-tene/styrene triblock copolymer of a high-density polyethylene and a male¬ated EPDM rubber, respectively. When maleated EPDM is the process aid, soft compositions can be obtained. Table III illustrates the use of different thermoplastic resins. Various polyester based plastic materials such as poly(butylene terephthalate-co-isophthalate) (Example 17), a modified polyethylene terephthalate) (Example 18), and a poly(butylene terephtha-late)/poly(tetramethylene glycol) segmented block copolymer (Example 19) can also be used in the practice of this invention. Table IV illustrates the applicability of plasticizers. The hard TPV composition of Example 20 was plasticized to softer compositions in Examples 21 and 22 with the aid of an isopropy-lated triphenyl phosphate as plasticizer. About 63 grams of the TPVs of Examples 20-22 were passed through a small single screw extruder at 500°F. Good melt strength was observed for these TPVs, with the plas¬ticized TPVs exhibiting good surface smoothness. The fair surface smoothness of the TPVs of Example 20 was improved in a formulation containing additional Polybond 3009 (Example 23). Examples 24-30 illus¬trate the suitability of various polar and nonpolar plasticizers. In the prac-. tice of this invention. TPVs OF NITRILE RUBBER AND THERMOPLASTIC POLYURETHANE The invention also relates to thermoplastic vulcanizates (TPVs) produced from thermoplastic polyurethane (TPUs) and carboxylated nitrile rubber (CNBR) utilizing addition type curatives and processing aids. The curatives of this invention have no direct or indirect ad¬verse effect on the polyurethane plastic phase as do some conventional rubber curatives such as phenolic resin and peroxide. For example, pheno¬lic resins produce water by the thermal decomposition which can subse¬quently breakdown the TPU causing carbon dioxide evolution. The cura¬tives also react with the acid groups of CNBR by an addition reaction which results in the crosslinking of the rubber without the evolution of volatiles (such as water) which can break down the TPU phase and com¬promise TPV physical properties. Trace amounts of water in a TPV com¬position can cause the thermoplastic phase to breakdown when proc¬essed. Residual steam or carbon dioxide liberated by the action of steam on the TPU can be contained in the melt, for example, in an extruder. As the extrudate exits the die, the release of pressure on the extrudate strand causes formation of gas bubbles and excessive extrudate swell. This phe¬nomenon was observed for the neat TPUs as well as TPU/CNBR TPVs produced with phenolic resin or peroxide as rubber curatives. The use of the curatives of the present invention considera¬bly reduced or eliminated the above noted problems, presumably due to a suitably formed TPV morphology. That is, the large plastic surface area generated due to the presence of small rubber particles helped degas the TPV melt within the extruder, thus allowing the preparation of a void free extrudate. Another adverse problem is that typically, molten TPUs stick to metal and cause difficulty in processing and equipment clean up. The TPVs of the present invention have a considerable reduced tendency to stick to metal when compared with TPUs. The present invention also dis¬closes the use of additives that further reduce molten TPV stickiness to metal, without compromising TPV physical properties. Considering the nitrile rubbers of the present invention, they are carboxylated and are blended with the polyurethane. The carboxylated nitrile rubbers are described herein above and the description thereof is hereby fully incorporated by reference. The amount of the conjugated diene content within the co¬polymer is thus generally a majority that is from about 50 percent to about 80 percent by weight and desirably from about 55 percent to about 75 percent by weight. The nitrile rubber utilized in this invention may also be par¬tially precrosslinked with a gel content of up to 80%. That is, up to 80% by weight of the rubber is not dissolved by boiling methyl ethyl ketone. The amounts of the one or more carboxylated nitrile rubbers is generally from about 50 to about 500 parts by weight, desirably from about 100 to about 300 parts by weight, and preferably about 200 to about 250 parts by weight for every 100 parts by weight of the one or more thermoplastic polyurethane polymers. The thermoplastic polyurethane is made in a conventional manner, as known in the art, as well as in literature. Typical polyure-thanes are made from a polyol intermediate and generally an equivalent amount of a polyisocyanate. The polyol intermediate is generally a liquid polyether polyol or a polyester polyol or combinations thereof having a number average of molecular weight of from about 450 to about 6,000 with from about 600 to about 4,500 being preferred. In order to avoid crosslinking, generally only polyether or polyester diols are utilized. Polyether polyols are generally made by reacting an alkylene oxide having from 2 to about 10 carbon atoms such as propylene oxide with a strong base such as potassium hydroxide, preferably in the pres¬ence of water, glycols and so forth. Polyether polyols made from ethylene oxide, propylene oxide, or epoxides, or copolymers thereof, are preferred. Other polyethers which can be utilized are those which are produced as by polymerization of tetrahydrofuran or epoxides such as epichlorohydrin, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, for exam¬ple in the presence of Lewis catalysts such as boron trifluoride, or by the addition of epoxides, preferably of ethylene oxide and propylene oxide, op¬tionally mixed or in succession, onto starter components with reactive hy¬drogen atoms such as water, alcohols, ammonia, or amines, for example ethylene glycol, 1,3- or 1,2-propylene glycol, water, 4,4'-dihydroxydiphenyl-propane, aniline, ethanolamine or ethylenediamine. Polyester polyols are formed from the condensation of one or more polyhydric alcohols having from 2 to 1 5 carbon atoms with one or more polycarboxylic acids having from 2 to 14 carbon atoms. Examples of suitable polyhydric alcohols include the following: ethylene glycol, pro¬pylene glycol such as 1,2-propylene glycol and 1,3-propylene glycol, glyc¬erol; pentaerythritol; trimethylolpropane; 1,4,6-octanetriol; butanediol; pentanediol; hexanediol; dodecanediol; octanediol; chloropentanediol, glyc¬erol monallyl ether; glycerol monoethyl ether, diethylene glcol; 2-ethylhexanediol-1,4; cyclohexanediol-1,4; 1,2,6-hexanetriol; 1,3,5-hexanetriol; 1,3-bis-(2-hydroxyethoxy) propane, 1,4- and 2,3-butylene gly¬col, neopentyl glycol, 1,4-bis(hydroxymethyl)cyclohexane, trimethy-lolethane, together with di-, tri-, tetra-, and higher polyethylene glycols, di-and higher polypropylene glycols, together with di- and higher polybuty-lene glycols, and the like. Examples of polycarboxylic acids include the following: phthalic acid; isophthalic acid; terephthalic acid; tetra-chlorophthalic acid; maleic acid; dodecylmaleic acid; octadecenylmaleic acid; fumaric acid; aconitic acid; trimellitic acid; tricarballylic acid; 3,3'-thiodipropionic acid; succinic acid; adipic acid; malonic acid, glutaric acid, pimelic acid, sebacic acid, cyclohexane-1,2-dicarboxylic acid; 1,4-chclohexadiene-1,2-dicarboxylic acid; 3-methyl-3,5-cyclohexadiene-1,2-dicarboxylic acid and the corresponding acid anhydrides such as tetrahy-drophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylenetetrahydrophtthqalic anhydride, acid chlorides and acid esters such as phthalic anhydride, phthaloyl chloride and the di¬methyl ester of phthalic acid, dimerized and trimerized unsaturated fatty acids, optionally mixed with monomeric unsaturated fatty acids, tereph¬thalic acid monomethyl ester and terephthalic acid monoglycol ester. Preferred polycarboxylic acids are the aliphatic and cycloaliphatic dicar-boxylic acids containing no more than 14 carbon atoms and the aromatic dicarboxylic acids containing no more than 14 atoms. Any polyhydric al¬cohol having more than 2 hydroxyl groups or any polycarboxylic acid hav¬ing more than 2 carboxylic groups used to make the polyesters should be used in only very minor amounts to prevent crosslinking and gelling. Polyesters from lactones (for example e-caprolactone) and polyacetals, polycarbonates or polybutadienes containing terminal hydroxyl groups are also suitable. Highly preferred polyol intermediates include polypropylene ether diol, poly-1,2-butylene ether diol, and most preferably poly-1,4-tetramethylene ether, and epsilon-polycaprolactone diols. Isocyanates which may be used are aliphatic, cycloaliphatic, araliphatic, aromatic and hetrocyclic polyisocyanates or any desired mix¬tures of these polyisocyanates (c.f. Houben-Weyl, Methoden der Or-ganischen Chemie, volume E 20, Makromolekulare Stoffe, Georg Thieme Verlag, Stuttgart, New York 1978, pages 1587-1593). Examples are eth- ylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, 1,3-cyclobutane diisocyanate, 1.3- and 1,4-dyclohexane diisocyanate together with any desired mixtures of these isomers, 1-isocyanato-3,3,5-trimethyl 5-isocyanatomethyl- cyclohexane, 2,4- and 2,6-hexahydrotolylene diisocyanate together with any desired mixtures of these isomers. Aromatic polyisocyanate is preferred and generally has a formula R(NCO)2. Inasmuch as combinations of various polyisocyanates can be utilized, it is to be understood that the amount is not necessarily an integer such as two. R is an aliphatic having from about 2 to about 20 carbon atoms with from about 6 to about 1 5 carbon atoms being pre¬ferred, or an aromatic including an alkyl substituted aromatic having from about 6 to about 20 carbon atoms with from about 6 to about 1 5 carbon atoms being preferred, or combinations thereof. Examples of suitable polyisocyanates include 1,6-diisocyanato hexane, 2,2,4-and/or 2,4,4-trimethyl hexamethylene diisocyanate, p-and m-tetramethyl xylene diiso¬cyanate, dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI), 4,4-methylene diphenyl isocyanate (MDI), p- and m-phenylene diisocyanate, 2.4- and/or 2,6-toluene diisocyanate (TDI), durene-1,4-diisocyanate, iso- phorone diisocyanate, isopropylene-bis-(p-phenylene) diisocyanate) and sulfone-bis-(p-phenylene) Diisocyanate. The various diphenyl methane diisocyanates (MDI) and mixtures of MDI with polymeric MDI having an average isocyanate functionality of approximately 2 is preferred. Isocyanates having a higher functionality can also be used, such as 4,4',4"-triphenylmethane triisocyanate, polyphenyl/polymethylene polyisocyanates (for example obtained by aniline/formaldehyde condensa¬tion and subsequent phosgenation), together with the distillation residues containing isocyanate groups which arise during industrial isocyanate pro¬duction, optionally dissolved in one or more of the above-stated polisocy-anates. However, care must be taken in this case to ensure that an aver- age functionality of two is not substantially exceeded if the polyurethanes are to be melt processed. It may optionally be necessary to compensate for reactants with an elevated functionality by also using other reactants with a functionality of lower than two. Monofunctional isocyanates suit¬able for this purpose are, for example, stearyl isocyanate, cyclohexyl iso-cyanate and phenyl isocyanate. Other descriptions of TPUs and TPU forming components in¬cluding disocyanates, hydroxy terminated polyethers and polyesters, and diamines, which can be utilized in the present invention, can be found in U.S. Patents 5,142,001, 5,739,252; and 5,905,133 which are incorpo¬rated fully herein by reference. TPUs containing crosslinked polyurethanes as set forth in U.S. Patent 5,908,894 are also suitable for the practice of this invention and is also hereby fully incorporated by reference. TPUs suitable for practice of this invention may be partially crystalline due to the hard segment content where the crystalline domains act as virtual crosslinks to render the TPU elastic and also allow thermo¬plastic processability at elevated temperatures by crystallite melting. Completely amorphous TPUs are also suitable for the practice of this in¬vention. The equivalent ratio of the polyisocyanate to the polyether or polyester polyol, i.e. NCO/OH is generally from about 0.90 to about 1.10, desirably from about 0.95 to about 1.05, and preferably from about 0.97 to about 1.03 The urethane prepolymers of the present invention are gener¬ally extended by a polyol having generally two active hydroxyl groups. Such extending polyols are generally discussed herein above with regard to the intermediate polyol and thus are fully incorporated by reference. Chain extenders generally have an average of 1.8 to 3.0 Zerewitinoff ac¬tive hydrogen atoms and a molecular weight of about 62 to about 400. These compounds include compounds containing amino groups, thiol groups or carboxyl groups and those with two to eight, preferably two hy-droxyl groups. Examples of chain extending compounds are di- and polyols such as ethylene glycol, 1,2- and 1,3-propylene glycol, 1,4-and 2,3- butylene glycol, 1,5-pentanediol, 1,6 hexanediol, 1,8-octanediol, neopentyl glycol, 1,4-bis(hydroxymethyl)cyclohexane, 2-methyl-1,3-propanediol, glycerol, trimethylolpropane, 1,2,6-hexanetriol, trimethylolethane and pen- taerythritol, di, tri-, tetra- and higher polyethylene glycols with a molecular weight of up to 400, together with di- and higher polypropylene glycols with a molecular weight of up to 400, 4,4'-dihydroxydiphenylpropane, di(hydroxymethyl)hydroquinone, ethanolamine, diethanolamine, N- methyldiethanolamine, triethanolamine and 3-aminopropanol; aliphatic diamines such as, for example, ethylenediamine, 1,4- tetramethylenediamine, hexamethylenediamine, together with the mixtures thereof, 1 -amino-3,3,5-trimethyl-5-aminomethylcyclohexane ("iso- phoronediamine"), 2,4- and 2,6-hexahydrotoluylenediamine together with the mixtures thereof, perhydro-2,4' and -4,4'-diaminodiphenylmethane, p-xylylenediamine and bis-(3-aminopropyl)methylamine; aromatic diamines which may be utilized are bisanthranilic acid esters, 3,5- and 2,4-diaminobenzoic acid esters, 3,3'-dichlord-4,4'-diaminodiphenylmethane, tolylenediamine and 4,4'-diaminodiphenylmethane. Chain extenders are utilized in an effective amount to achieve desired end results. Compounds which are monofunctional towards isocyanates may also be used in proportions of up to 2 wt. %, relative to the thermo¬plastic polyurethaneurea elastomer, as chain terminators. Suitable com¬pounds are, for example, monoamines such as butyl- and dibutylamine, octylamine, stearylamine, N-methylstearylamine, pyrrolidine, piperidine and cyclohexylamine, monoalcohols such as butanol, 2-ethylhexanol, octanol, dodecanol, the various amyl alcohols, cyclohexanol and ethylene glcol monomethyl ether, with 2-ethylhexanol and ethylene glycol monomethyl ether being preferred. Catalysts are often utilized to promote the urethane chain ex¬tension and preferably include tin compounds such as, for example, vari¬ous stannous carboxylates such as stannous acetate, stannous octoate, stannous laurate, stannous oleate and the like; or dialkyl tin salts of car-boxylic acids such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, dibutyltin di-2-ethylhexoate, dilauryltin diacetate, dioctyltin diace¬tate and the like. As an alternative or in addition to the above tin com¬pounds, various tertiary amines can be used such as triethylamine, ben-zyldimethylamine, triethylenediamine, and tetramethylbutanediamine. The tin catalysts, when utilized, are generally used in amount of 0.5 parts or less, i.e., in the range of about 0.01 to 0.5 parts, by weight per 100 parts of prepolymer. The tertiary amine catalysts, when utilized, can be used in amounts of 0.01 to about 5 parts by weight per 100 parts of prepolymer. In addition to the above catalysts, further compounds which may be con¬sidered are: titanium, bismuth and antimony compounds, such as for ex¬ample antimony triisopropoxide, antimony octcate, antimony tallate, bis¬muth salts of carboxylic acids with 2 to 20 carbon atoms, such as for ex¬ample bismuth trioctanoate, dibutylbismuth octanoate, triphenylbismuth didecanoate and dibutyltitanium bis(acetylacetonate). Further usable catalysts together with details of the mode of action of the catalysts are described in Kunststoff Handbuch volume VII, Polyurethane, edited by Vieweg Hochtlen, Carl Hanser Verlag, Munich 1966, for example on pages 96 to 102. The amount of catalysts, when utilized, is generally from about 0.01 to about 1.0 parts by weight per 100 parts by weight of the prepolymer. Stickiness to metal of the molten products of this invention can be reduced by the addition of maleated hydrocarbon polymers to the desired TPV composition (TPU/carboxylated NBR) either prior or subse- quent to dynamic vulcanization. The various processing aids enhance processing properties. Such processing aids or agents are described herein above and accordingly fully incorporated by reference. Desirable processing agents are maleated polyethylene or maleated polypropylene, that is, a graft of maleic anhydride and polyethylene or polypropylene, maleated ethylene/ a-olefin copolymers having an a-olefin content of from about 0 or 1 to about 55 wt %, said a-olefins including propylene, 1-butene, 1-hexane, 1-octane, styrene and alkylated styrenes (methylsty-rene, ethylstyrene). Further desired processing aids are maleated styrene-ethylene/butene-styrene triblock copolymer, maleated EP rubber, ethylene-acrylate-glycidylmethacrylate copolymers, ethylene-acrylate-acid functional rubber, ethylene/methyl acrylate/acid functional rubber (such as "Vamac" from Dupont), poly(ethylene/vinyl acetate/methacrylic acid), poly(ethylene/vinyl acetate)-graft maleic anhydride, poly(ethylene/glycidyl methacrylate) GMA), poly(ethylene/acrylic or methacrylic acid), poly(propylene/acrylic or methacrylic acid), maleic anhydride/cc-olefin co¬polymers (such as maleic anhydride/1-octene copolymer), or maleic anhy-dride/styrene copolymers or combinations of the above mentioned proc¬essing agents can be used. Other desirable processing aids include poly¬ethylene, polypropylene, ethylene-propylene rubber, EPDM rubber, or eth¬ylene/1-olefin copolymers (such as ethylene /1-butene, ethylene/1 -hexene, ethylene/1-octene) grafted with 1 to 6 weight percent of acrylic or methacrylic acid or 1 to 60 weight percent of styrene/acrylonitrile copoly¬mer where acrylonitrile content can range from 5% to 95%. Preferred processing aids include maleated polypropylene, maleated polyethylene, maleated EP Rubber, and maleated ethylene/a-olefin rubber such as ethyl-ene/butene copolymer. The amount of a processing or compatabilizing agent gener¬ally ranges from about 2 to about 20 parts by weight and preferably from about 5 to about 1 5 parts by weight based upon 100 parts per weight of the thermoplastic polyurethane resin. As with thermoplastic vulcanizates of carboxylated nitrile rubber and polyester thermoplastics discussed herein above, the thermo¬plastic vulcanizates of carboxylated nitrile rubber and thermoplastic poly-urethanes are prepared by dynamic vulcanization which generally results in the formation of a compatible blend of the polyurethane as a continuous phase and the nitrile rubber as a discontinuous phase. However, other possible morphologies can also exist. The nitrile rubber is cured utilizing various curative com¬pounds including oxazoline, oxazine, and imidazolines such as bisimida-zoline. More specifically, the nitrile rubber phase is cured via the bound acid functionality present, using addition type curing agents such as prefr erably 1,3-phenylene-bis 2,2'-(oxazoline-2), which avoids the generation of undesirable volatiles. An important aspect of the present invention is the utilization of addition type curatives which, do not break down the plastic phase and do not form volatile compounds such as water. While other curing agents can be utilized such as free radical generating compounds, the same are not desired and thus used in small amounts such as generally less than 1.0 parts by weight and desirably less than 0.5 parts by weight based upon 100 parts by weight of the carboxylated nitrile rubber. A highly pre¬ferred addition curative or cross-linking agent is the various oxazolines or oxazines such as those having the formula wherein R or R' is an aliphatic or aromatic hydrocarbon group such as al-kylene or arylene having 1 to 24 carbon atoms optionally substituted with one or more alkyl groups having 1 to 6 carbon atoms or substituted with an aryl group having 6 to 9 carbon atoms; n is 0 or 1, when n equals 1 then X and Y are hydrogen atoms or independently an 2-oxazoline group or a 1,3-oxazine group, or a 2-oxazoline group or a 1,3-oxazine group and a hydrogen atom, with the remaining carbon atoms having hydrogen at¬oms thereon, p and q, independently, is 1 or 2, and when n equals 0 then R, X , and Y are nonexistent. Further, each oxazoline group of the above formula may optionally be substituted with an alkyl of 1 to 6 carbon at¬oms. Further descriptions of said polyvalent oxazolines are set forth in U.S. Patent 4,806,588, herein incorporated by reference. Preferred oxa¬zolines include 2,2'-bis(oxazoline-2), 2,2'hexamethylenedicarbamoylbis (oxazoline-2), and 1,3-phenylene-2,2'bis(oxazoline-2). As a result of inertness towards the molten TPU, the curatives of the present invention allow the preparation of TPVs with enhanced properties over the corresponding simple rubber and plastic blends, which is not attainable by the use of conventional nitrile rubber cure systems, such as peroxides. Practice of the present invention also allows the prepa¬ration of TPU containing products with improved processability over con¬ventional TPUs due to the ready degassability of the molten material of this invention, and also due to the greatly reduced stickiness of the molten TPV to metal. The amount of the curative utilized is generally from about .05 to about 12, desirably from about 0.75 to about 8, and preferably from about 1 to about 5 parts by weight for every 100 parts by weight of a carboxylated nitrile rubber. As noted above, the present invention is desirably substan¬tially free of and preferably is completely free of curatives such as sulfur, peroxide, and phenolic resins. Curing with sulfur leads to unstable phase morphology. Peroxides are not used because they are known to affect the plastic phase (see U.S. Patent 5,760,158), which would adversely affect processability as noted above. By the term "substantially free" is meant that the total amount of sulfur, peroxide, or phenolic resin or combinations thereof, is generally less than 2, desirably less than 1.0, preferably less than 0.5 parts by weight per 100 parts by weight of said rubber. The carboxylated nitrile rubber-polyurethane blends of the current invention can contain various conventional additives, such as rein¬forcing and non-reinforcing fillers extenders, etc., as set forth herein above and also fully incorporated by reference. Dynamic vulcanization is utilized to blend and cure the nitrile rubber-polyurethane blend. Generally, the degree of cured of carboxylated nitrile rubber is at least about 70 or 80, desirably at least 85, and prefera¬bly 90 or 95 percent. The manner in which such a blend is mixed and cured is set forth herein above. The present invention will be better understood by reference of the following examples, which serve to illustrate but not limit the pre¬sent invention. EXAMPLES Thermoplastic vulcanizates (TPVs) of the present invention were produced in a Brabender-Plasticorder model EPL-VS502. The mixing bowl had a capacity of 85 ml with cam rotors, which gave good mixing. TPVs were prepared at 200°C and 75 rpm rotor speed unless specified otherwise. The TPUs were heated to temperature in the mixer about 2-1/2 min. before rubber addition. About 4-1/2 min. after rubber addition the machine torque leveled off, indicating the formation of a uniform rub¬ber and plastic molten blend. At this time, the curative 1,3-phenylene bis 2,2'(oxazoline-2) (1,3 PBO) was added which caused a torque rise for about 2 min after which the machine torque leveled off. The molten TPV was further mixed for five more minutes, after which it was removed from the Brabender, sheeted in a cold press, and subsequently compression molded at 410° F to obtain plaques for physical testing. Compression set was measured on plied discs as per ASTM method B. When neat TPV or TPU/rubber blend properties were meas ured, the desired samples were obtained by heating the plastic pellets or pellet/rubber blend for about 10-11 minutes in the Brabender at 200° C and 75 rpm. Plaques for testing were obtained from the molten product as described earlier. Example 1 sets forth the physical properties of a hard poly-ether based amorphous TPU obtained from pellets provided by BASF. The TPU pellets were not dried before use. The tensile strength, ultimate elongation, and compression set data were a close match to that of the material specifications. The sample of Example 2 was produced by adding phenolic resin (resole type) to the molten TPU of Example 1. TPU pellets were masticated in the Brabender at 75 rpm and 200° C for about seven minutes before phenolic resin addition.. On phenolic resin addition, the machine torque increased gradually and leveled off only at about 16 min¬utes after curative addition. Undoubtedly a reaction was occurring be¬tween the phenolic resin and the TPU. It is also known that water, a by¬product of phenol resin heating, causes TPU chemical degradation and subsequent carbon dioxide evolution from the molten plastic. As the data of Example 2 indicates, the action of phenolic resin on the TPU has caused a deterioration of TPU compression set properties. Hence, phenolic resin is not a suitable curative for the olefinic unsaturation in the rubber during TPU/carboxylated NBR TPV formation. This is further illustrated by the comparison of the physical properties of the product of Example 3 (TPU/CNBR blend) with those of Example 4 (TPV/CNBR TPV produced with phenolic resin cure for the rubber phase). Elastic recovery as meas¬ured by compression set is actually worse for the TPV (Example 4) when compared with that of the blend (Example 3). This data illustrates the fact that the rubber curative should not affect the TPV plastic phase so that products with suitable physical properties and processability may be ob¬tained (see also later discussion). Peroxide is also an unsuitable rubber curative when TPU forms the TPV plastic phase. In Examples 5-7, a peroxide and a coagent that assists peroxide cure of the rubber were separately (Examples 5,6) or together (Example 7) dispersed into the rubber at room temperature before rubber addition to the molten TPU, in order to ensure as low of an expo¬sure of the peroxide to the TPU during dynamic vulcanization. It is clear that suitable vulcanization did not take place in Examples 5-7 when com¬paring the physical properties of these products (especially compression set) to the unvulcanized rubber and plastic blend of Example 8. The products of Examples 1-8 were fed through a small labo¬ratory single screw extender (about 60g was the minimum amount of ma¬terial required) at 400° F in order to extrude a solid tube of material. In all cases, extrudate swell to 2-3 times the die diameter and the presence of a considerable number of expanding gas bubbles in the melt was observed. In Examples 1 and 8, residual moisture in the TPU undoubtedly cause some TPU chemical degradation. The residual moisture and/or carbon di¬oxide generated from the TPU degradation was not completely devolital-ized in the extruder, but continued to be held in the melt under pressure. In contrast to the phenolic resin and peroxide rubber cura¬tives, 1,3-PBO does not breakdown the TPU plastic phase, and the curing reactive of 1,3-PBO with the rubber is an addition reaction of the oxazoline functionality with the acid groups in the rubber, thereby avoiding the evo¬lution of volatiles that can cause polymeric material breakdown and/or ma¬terial processing problems. There is a considerable enhancement in physi¬cal properties (tensile strength, compression set) when the properties of a TPU/carboxylated NBR blend (Examples 8, 9) are compared to the corre¬sponding dynamic vulcanizates (Examples 10, 11) where 1,3-PBO was used as the rubber curative. Solid tube extrudates of the TPV samples of Examples 10 and 11 exhibited minimum die swell and gas bubble entrap¬ment when compared with the corresponding blends of Examples 8 and 9 or the products of Examples 1-7. In fact, no gas bubbles were visible in the extrudate of the sample of Example 10. TPV morphology consists of micron sized crosslinked rubber particles in a continuous plastic matrix. Hence, on dynamic vulcanization, the relatively low area of contact between the rubber and plastic phase in the blend is increased tremendously in the vulcanizate due to the increased surface area provided by the particulate rubber. Presumably, this in¬creased surface area established for the plastic phase allows efficient de¬gassing of the product while in the extruder, thereby improving extrudate quality over that of the neat TPU, rubber/plastic blends, and resin or perox¬ide cured dynamic vulcanizates where the appropriate TPV morphology may not be formed. Hence the TPUs of this invention have a processing advantage over TPUs and other TPVs where phenolic resin or peroxide is used as the rubber phase curative. As previously observed, physical properties are improved on curing the TPU/CNBR/maleated polyolefin blends with 1,3-PBO by dy¬namic vulcanization (compare Examples 13 and 14). The neat TPUs used in Examples 1 and 12 were very sticky and difficult to remove from the mixer in the molten state. The TPU/carboxylated NBR blends were also sticky, though less so than the neat TPUs. The products of Examples 2-7 were also very sticky. The TPVs of this invention, where 1,3-PBO was the curative, were much less sticky and could easily be removed from the mixer without any residual material being stuck to the mixing chamber or rotors. Product stickiness could further be reduced and product removal from the mixer could further be enhanced by the addition of maleated polyolefins to the mix before or after dynamic vulcanization (Examples 14-16). This is particularly impor¬tant for products obtained using the soft TPU (85 Shore A) as the plastic phase, which gave very sticky products without the benefit of the addi¬tives of this invention. The addition of a limited amount of the desired ad¬ditives does not affect TPV properties as per the data provided (compare Examples 10 and 16; 11 and 18). Example 19 illustrates the preparation of a non-sticky, very soft TPU based TPV. Examples 21 and 22 illustrate the applicability of this inven¬tion in the case where the TPU plastic phase is partially crystalline. In Ex¬ample 20, the physical properties of the neat crystalline TPU are listed. Practice of this invention also allows the preparation of TPVs with increased upper service temperature over comparable TPUs. The drop in modulus with temperature for a TPV of this invention is lower than that observed for a comparable hardness TPU, indicating an increased up¬per service temperature for the products of this invention. A drop in modulus of 17.9% is observed when the temperature is increased from 50°C to 80°C for the TPV of Example 16 (87 Shore A hardness). In com¬parison, the observed drop in modulus for an 83 Shore A TPU is 33.5% (Example 12), and 41.6% for a 92 Shore A TPU (Example 1). At 100°C the TPV of Example 16 has lost 31.3% of its elastic modulus at 50°C, whereas the loss for the TPUs of Examples 12 and 1 is 47% and 52.8%, respectively. It is reasonable to conclude that the service temperature of the TPV of Example 16 has been raised at least 20°C over that of the TPUs of Examples 12 and 1. A similar conclusion can be drawn in the case of the TPV of Example 22 in comparison to the TPU of Example 20. In fact, the TPU test bar of Example 20 lost its physical integrity at 160°C, whereas the TPV of Example 22 maintained its physical integrity to 200°C. In summary, the TPVs of this invention provide over the cur¬rently available TPVs: 1. Improved melt processability by providing a mechanism for efficient product melt phase degassing. 2. Improved processability due to the decreased tendency of the product melt to adhere to metal. 3. Improved TPV physical properties using the curatives of this invention. 4. Increased upper service temperature for the TPV. TPVs were prepared at 220°C for this set of experiments. Elastomeric Materials: Nipol 1072 X 28: Carboxylic acid functional nitrile rubber. Bound acrylonitrile ~ 27 weight percent. Carboxylic acid content: - 0.08 equivalents per hundred parts of rubber. Gel content: 50-60 weight per¬cent in methyl ethyl ketone (Zeon Chemicals, Inc., Louisville, KY.). Thermoplastic Polyurethanes: Elastollan 1195A: 95 Shore A hardness amorphous polyether based poly- urethane (BASF Corporation, Wyandotte, Ml). Elastollan 1185A: 85 Shore A hardness amorphous polyether based poly-urethane (BASF Corporation, Wyandotte, Ml). Estane 58155: 65 Shore D hardness partially crystalline (MP 182°C, 192°C, 205°C - DDS peaks) polyether based polyurethane (B.F.Goodrich Company, Brecksville, OH). Process Aids: Polybond 3009: Malected high density polyethylene with 1 weight per¬cent bound maleic anhydride (Uniroyal Chemical Company, Middlebury, CT). MEB Copolymer: maleated ethylene/butene copolymer Antioxidant: Irganox B225: Phenolic/phosphite based antioxidant (Ciba Specialty Chemicals Corporation, Troy, Ml). Crosslinkinq Compounds: 1,3-PBO: 1,3-phenylenebis2,2'-(oxazoline-2) (Tramaco Japan Ltd., Tokyo, Japan). SP-1045: Alkylated phenol/formadehyde resole type resin (Schenectady International, Inc., Schenectady, NY). HVA-2: 2,4-bismaleimidotoluene (DuPont Dow Elastomers, Stow, OH). Vulcup 40KE: 40 weight percent 1,4-bis-(t-butylperoxyisopropyl benzene) on silane modified clay (Harwick Chemical, Akron, OH). i We Claim 1. A process for preparing a thermoplastic vulcanizate comprising dynamically vulcanizing a blend of a) an engineering thermoplastic selected from the group consisting of polyester, polycarbonate, polyester block copolymer or combinations thereo having a melting point of at least 170°C and below 260°C and a weight average molecular weight above 40.000. b) from 200 to 375 parts by weight of carboxylated nitrile rubber per 100 parts by weight of said thermoplastic. c) from 1 to 12 parts by weight of an addition type curing agent per 100 parts by weight of said rubber and d) from 3 to 30 parts by weight per 100 parts by weight of said thermoplastic of a processing aid selected from the group consisting of functionalized polyolefins derived from C2-8 monomers, functionalized polyolefins derived from C2-8 monomers copolymerized with C3-10 unsaturated acids, ethylene vinyl alcohol copolymers, ethylene vinyl acetate copolymers, functionalized ethylene-propylene copolymers, functionalized ethylene-propylene-diene copolymers, functionalized styrenic block copolymers or combinations thereof. 2. A process as claimed in claim 1, wherein the repeat groups containing carboxylic acid groups in said nitrile rubber are from 1 to 10 parts by weight based upon 100 parts by weight of the conjugated diene and the acrylonitrile repeat groups in said nitrile rubber. 3. A process as claimed in claim 1, wherein said addition type curative is an oxazoline, an oxazine, a phenolic resin, a bismaleimide, an isocyanate, a carbodiimide, a bisimidazoline, a multifunctional epoxide, a multifunctional aziridine, or combinations thereof. 4. A process according to claim 1, wherein said processing aid is selected from the group consisting of an ethylene-acrylic acid copolymer, maleated polyethylene, maleated polypropylene, maleated ethylene-propylene rubber, a maleated block copolymer of styrene-butadiene-styrene, a maleated block copolymer of styrene-ethylene-butene-styrene, or combinations thereof. 4. A process as claimed in claim 1, wherein said thermoplastic is poly(butylene terephthalate), poly(ethylene terephthalate), or combinations thereof, wherein said nitrile rubber contains from 3 to 7 parts by weight of said carboxylic acid repeat groups therein, wherein said vulcanizate is at least 90 percent cured, and wherein the amount of said processing aid is from 5 to 20 parts by weight per 100 parts by weight of said thermoplastic. 5. A process as claimed in claim 4, wherein said processing aid is maleated polyethylene, and wherein said curative is 2,2'-bis(oxazoline-2), 2,2'-hexamethylenedicarbamoylbis(oxazoline-2), l,3-phenylene-2,2'-bis(oxazoline-2), or combinations thereof. 6. A process as claimed in claim 10, wherein said composition has an oil swell weight gain of 25 percent or less at 150°C for 72 hours. 7.A process for preparing a thermoplastic vulcanizate substantially as herein before described with reference to the foregoing examples. Dated this the 3rd day of August, 2000 [JAYANTA PAL] Of Remfry & Sagar ATTORNEY FOR THE APPLICANT[S]

Documents:

726-mum-2000-cancelled page(24-10-2005).pdf

726-mum-2000-claim (granted)-(24-10-2005).pdf

726-mum-2000-claim(granted)-(24-10-2005).doc

726-mum-2000-correspondence(7-5-2007).pdf

726-mum-2000-correspondence(ipo)-(21-10-2004).pdf

726-mum-2000-form 1-(21-10-2004).pdf

726-mum-2000-form 1-(3-8-2000).pdf

726-mum-2000-form 19(3-8-2004).pdf

726-mum-2000-form 2 (granted)-(24-10-2005).doc

726-mum-2000-form 2 (granted)-(24-10-2005).pdf

726-mum-2000-form 3(14-10-2005).pdf

726-mum-2000-form 3(3-8-2000).pdf

726-mum-2000-form 5(3-8-2000).pdf

726-mum-2000-petition under rule 137(14-10-2005).pdf

726-mum-2000-petition under rule 138(14-10-2005).pdf

726-mum-2000-poweof attorniy(7-12-2000).pdf

726-mum-2000-power of aouthority(14-10-2005).pdf