|Title of Invention||
"PROCESS FOR PREPARING A POLYISOCYANURATE POLYURETHANE MATERIAL"
|Abstract||A process for preparing a polyisocyanurate polyurethane material, which process comprises reacting a polyisocyanate and an isocyanate-reactive composition, wherein the reaction is conducted at an isocyanate index of 150 to 1500 and in the presence of a trimerisation catalyst.|
[001 ] Process for preparing a polyisocyanurate polyurethane material
 The present invention is related to a process for preparing a polyisocyanurate
 More specifically the present invention is related to a process for preparing a poly-
isocyanurate polyurethane material using a polyether polyol having a high oxyethylene
content and a polyisocyanate having a high diphenylmethane diisocyanate (MDI)
 The preparation of polyurethane materials having a low and a high hardblock
content from polyols having a high oxyethylene content, polyisocyanates comprising at least 85% by weight of 4,4'-MDI or a variant thereof and water has been disclosed in WO 02/06370 and WO 98/00450. The materials made are polyurethane elastomers. Further it has been disclosed in EP 608626 to produce shape memory polyurethane foams by reacting a polyisocyanate comprising a high amount of 4,4'-MDI and a polyol with a high oxyethylene content with water. WO 02/10249 discloses a process for preparing a polyurethane material having a high hard block content by reacting an MDI, a polyol having a high oxyethylene content and a cross-linker/chain extender.
 These citations do not disclose a process for making a polyisocyanurate
polyurethane material by reacting a polyisocyanate and a polyol at a high NCO-index and in the presence of a trimerisation catalyst.
 Processes for making polyisocyanurate polyurethane materials, by reacting poly-
isocyanates and polyols at a high index in the presence of a trimerisation catalyst, as such have been widely described. See e.g. EP 922063 and WO 00/29459, WO 02/00752, EP 1173495, EP 745627, EP 587317, US 4247656, US 4129697 , DE 10145458, US 4661533, US 4424288 and GB 1433642.
 Surprisingly we have found a novel class of polyisocyanurate polyurethane
materials prepared from certain MDI-based polyisocyanates and certain polyols having a high oxyethylene content.
 The invention allows for the production of materials having a high modulus, a high impact-, temperature- and flammability resistance, a short demould time and a high green strength. In particular the materials can be advantageously produced according to the reaction injection moulding (RIM) process.
 Further, the process is suitable to make reinforced materials by using fillers like
organic particles and mineral particles like nanoclay particles, BaSO and CaCO and/ or fibers like glass fibers, natural fibers like flax, hemp and sisal fibers, synthetic fibers like polyamides (Kevlar™) and polyethylene (Spectra™). Such materials exhibit a good thermal stability.
 Still further the ingredients used to make the materials are easily processable and
exhibit excellent curing characteristics allowing for short demould times.
 Still further the materials obtained show lower levels of residual NCO groups in
infra-red analysis compared to materials made from high amounts of polyols having a high level of oxypropylene groups at the same NCO-index. The materials according to the present invention show a higher impact and are less brittle.
 Therefore the present invention is concerned with a process for preparing a polyiso-
cyanurate polyurethane material which process comprises reacting a polyisocyanate and an isocyanate-reactive composition wherein the reaction is conducted at an isocyanate index of 150 to 1500, the polyisocyanate consists of a) 80-100% by weight of diphenylmethane diisocyanate comprising at least 40%, preferably at least 60% and most preferably at least 85% by weight of 4,4'-diphenylmethane diisocyanate and/or a variant of said diphenylmethane diisocyanate which variant is liquid at 25°C and has an NCO value of at least 20% by weight (polyisocyanate a), and b) 20-0% by weight of another polyisocyanate (polyisocyanate b), and wherein the isocyanate-reactive composition consists of a) 80-100% by weight of a polyether polyol having an average nominal functionality of 2-6, an average equivalent weight of 150-1000, an average molecular weight of 600-5000, an oxyethylene (EO) content of 75-100% by weight, and b) an 20-0% by weight of one or more other isocyanate-reactive compounds excluding water, the amount of polyol a) and compound b) being calculated on the total amount of this polyol a) and compound b).
 In the context of the present invention the following terms have the following
1. isocyanate index or NCO index or index :
the ratio of NCO-groups over isocyanate-reactive hydrogen atoms present in a formulation, given as a percentage : [coded mathematical formula included] In other words the NCO-index expresses the percentage of isocyanate actually used in a formulation with respect to the amount of isocyanate theoretically required for reacting with the amount of isocyanate-reactive hydrogen used in a formulation.
It should be observed that the isocyanate index as used herein is considered from the point of view of the actual polymerisation process preparing the material involving the isocyanate ingredient and the isocyanate-reactive ingredients. Any isocyanate groups consumed in a preliminary step to produce modified polyisocyanates (including such isocyanate-dertvatives referred to in the art as prepolymers) or any active hydrogens consumed in a preliminary step (e.g. reacted with isocyanate to produce modified polyols or polyamines) are not taken into account in the calculation of the isocyanate index. Only the
free isocyanate groups and the free isocyanate-reactive hydrogens (including those of the water) present at the actual polymerisation stage are taken into account.
2. The expression "isocyanate-reactive hydrogen atoms" as used herein for the
purpose of calculating the isocyanate index refers to the total of active
hydrogen atoms in hydroxyl and amine groups present in the reactive com
positions; this means that for the purpose of calculating the isocyanate index
at the actual polymerisation process one hydroxyl group is considered to
comprise one reactive hydrogen, one primary amine group is considered to
comprise one reactive hydrogen and one water molecule is considered to
comprise two active hydrogens.
3. Reaction system : a combination of components wherein the polyisocyanates
are kept in one or more containers separate from the isocyanate-reactive
4. The expression "polyisocyanurate polyurethane material" as used herein
refers to cellular or non-cellular products as obtained by reacting the
mentioned polyisocyanates and isocyanate-reactive compositions in the
presence of trimerization catalysts at a high index, optionally using foaming
agents, and in particular includes cellular products obtained with water as
reactive foaming agent (involving a reaction of water with isocyanate groups
yielding urea linkages and carbon dioxide and producing polyurea-
5. The term "average nominal hydroxyl functionality" is used herein to indicate
the number average functionality (number of hydroxyl groups per molecule)
of the polyol or polyol composition on the assumption that this is the number
average functionality (number of active hydrogen atoms per molecule) of the
initiator(s) used in their preparation although in practice it will often be
somewhat less because of some terminal unsatoration.
6. The word "average" refers to number average unless indicated otherwise.
 Preferably the polyisocyanate a) is selected from 1) a diphenylmethane diisocyanate
comprising at least 40%, preferably at least 60% and most preferably at least 85% by weight of 4,4'-diphenylmethane diisocyanate and the following preferred variants of such diphenylmethane diisocyanate ; 2) a carbodiimide and/or uretonimine modified variant of polyisocyanate 1), the variant having an NCO value of 20% by weight or more; 3) a urethane modified variant of polyisocyanate 1), the variant having an NCO value of 20% by weight or more and being the reaction product of an excess of polyisocyanate 1) and of a polyol having an average nominal hydroxyl functionality of 2-4 and an average molecular weight of at most 1000; 4) a prepolymer having an NCO
value of 20% by weight or more and which is the reaction product of an excess of any of the aforementioned polyisocyanates 1-3) and of apolyol having an average nominal functionality of 2-6, an average molecular weight of 2000-12000 and preferably an hydroxyl value of 15 to 60 mg KOH/g, and 5) mixtures of any of the aforementioned pulyisocyanates. Polyisocyanates 1) and 2) and mixtures thereof are preferred as poly-isocyanate a).
 Polyisocyanate 1) comprises at least 40% by weight of 4,4'-MDI. Such poly-
isocyanates are known in the art and include pure 4,4'-MDI and isomeric mixtures of 4,4'-MDI and up to 60% by weight of 2,4'-MDI and 2,2'-MDI.
 It is to be noted that the amount of 2,2'- MDI in the isomeric mixtures is rather at an
impurity level and in general will not exceed 2% by weight, the remainder being
4,4' -MDI and 2,4'-MDI. Polyisocyanates as these are known in the art and com
mercially available; for example Suprasec MPR ex Huntsman Polyurethanes, which
is a business of Huntsman International LLC (who owns the Suprasec trademark).
 The carbodiimide and/or uretonimine modified variants of the above polyisocyanate
1) are also known in the art and commercially available; e.g. Suprasec 2020, ex Huntsman Polyurethanes.
 Urethaiie modified variants of the above polyisocyanate 1) are also known in the
art, see e.g. The ICI Polyurethanes Book by G. Woods 1990,21"1 edition, pages 32-35. Aforementioned prepolymers of polyisocyanate 1) having an NCO value of 20% by weight or more are also known in the art. Preferably the polyol used for making these prepolymers is selected from polyester polyols and polyether polyols and especially from polyoxyethylene polyoxypropylene polyols having an average nominal functionality of 2-4, an average molecular weight of 2500-8000, and preferably an hydroxyl value of 15-60 mg KOH/g and preferably either an oxyethylene content of 5-25% by weight, which oxyethylene preferably is at the end of the polymer chains, or an oxyethylene content of 50-90% by weight, which oxyethylene preferably is randomly distributed over the polymer chains.
 Mixtures of the aforementioned polyisocyanates may be used as well, see e.g. The ICI Polyurethanes Book by G. Woods 1990, 2nd edition pages 32-35. An example of such a commercially available polyisocyanate is Suprasec 2021 ex Huntsman Polyurethanes.  The other polyisocyanate b) may be chosen from aliphatic, cycloaliphatic, ar-
alipbatic and, preferably, aromatic polyisocyanates, such as toluene diisocyanate in the form of its 2,4 and 2,6-isomers and mixtures thereof and mixtures of diphenylmethane diisocyanates (MDI) and oligomers thereof having an isocyanate functionality greater than 2 known in the art as "crude" or polymeric MDI (polymethylene polyphenylene polyisocyanates). Mixtures of toluene diisocyanate and polymethylene polyphenylene
polyisocyanates may be used as well.
 When polyisocyanates are used which have an NCO functionality of more than 2,
the amount of such polyisocyanate used is such that the average NCO functionality of the total polyisocyanate used in the present invention is 2.0-2.2 preferably.
 Polyether polyol a) having a high EO content is selected from those having an EO
content of 75-100% by weight calculated on the weight of the polyether polyol. These polyether polyols may contain other oxyalkylene groups like oxypropylene and/or oxybutylene groups. These polyols have an average nominal functionality of 2-6 and more preferably of 2-4, an average equivalent weight of 150-1000 and a molecular weight of 600-5000, preferably of 600-3000. If the polyol contains oxyethylene groups and another oxyaikylene group like oxypropylene, the polyol may be of the type of a random distribution, a block copolymer distribution or a combination thereof. Mixtures of polyols may be used. Methods to prepare such polyols are known and such polyols are commercially available; examples are Caradol 3602 from Shell, Lupranol™ 9205 from BASF, Daltocel F526 ex Huntsman Polyurethanes (Daltocel is a trademark of Huntsman International LLC) and G2005 ex Uniqema. Preferably they are used in an amount of 90-100% by weight.
 The other isocyanate-reacrive compounds b), which may be used in an amount of
0-20% by weight and preferably of 0-10% by weight, may be selected from chain
extenders, cross-linkers, polyether polyamines, polyester polyols and polyether polyols
(different from the above described ones) having a molecular weight of more than 500
and in particular from such other polyether polyols, which may be selected from poly-
oxypropylene polyols, polyoxyethylene polyoxypropylene polyols having an
oxyethylene content of less than 75% by weight and polyoxyethylene poly
oxypropylene polyols having a primary hydroxyl content of less than 70%. Preferred
polyoxyethylene polyoxypropylene polyols are those having an oxyethylene content of
5-30% and preferably 10-25% by weight, wherein all the oxyethylene groups are at the
end of the polymer chains (so-called EO-capped polyols) and those having an
oxyethylene content of 60-90% by weight and having all oxyethylene groups and
oxypropylene groups randomly distributed and a primary hydroxyl content of 20-60%,
calculated on the number of primary and secondary hydroxyl groups in the polyol.
Preferably these other polyether polyols have an average nominal functionality of 2-6,
more preferably 2-4 and an average molecular weight of 2000-10000, more preferably
 The isocyanate-reactive chain extenders, which have a functionality of 2, may be
selected from amines, amino-alcohols and polyols; preferably polyols are used. Further the chain extenders may be aromatic, cycloaliphatic, araliphatic and aliphatic; preferably aliphatic ones are used. The chain extenders have a molecular weight of 500
of less. Most preferred are aliphatic diols having a molecular weight of 62-500, such as ethylene glycol, 1,3-propanediol, 2-methyl-l,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, 1,3-pentanedioI, 1,2-hexanediol, 3-methylpentane-l,5-dioI,
2,2-dijmethyl-l,3-propanedioI, diethylene glycol, dipropylene glycol and tripropylene
glycol, and aromatic diols and propoxylated and/or ethoxylated products thereof. The
cross-linkers are isocyanate-reactive compounds having an average molecular weight
of 500 or less and a functionality of 3-8. Examples of such cross-linkers are glycerol,
trimethylolpropane, pentaerythritol, sucrose, sorbitol, mono-, di- and triethanolamine,
ethylenediamine, toluenediamine, diethyltoluene diamine, polyoxyethylene polyols
having an average nominal functionality of 3-8 and an average molecular weight of
500 or less like ethoxylated glycerol, trimethylol propane, pentaerythritol, sucrose and
sorbitol having said molecular weight, and polyether diamines and triamines having an
average molecular weight of 500 or less; most preferred cross-linkers are the polyol
 Still further the other isocyanate-reactive compounds may be selected from
polyesters, polyesteramides, polythioethers, polycarbonates, polyacetals, polyolefins or polysiloxanes. Polyester polyols which may be used include hydroxyl-terminated reaction products of dihydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol or cyclohexane dimethanol or mixtures of such dihydric alcohols, and dicarboxylic acids or their ester-forrairig derivatives, for example succinic, glutaric and adipic acids or their dimethyl esters, sebacic acid, phthalic anhydride, tetrachlorophthalic anhydride or dimethyl terephthalate or mixtures thereof. Polythioether polyols, which may be used, include products obtained by condensing thiodiglycol either alone or with other glycols, alkylene oxides, dicarboxylic acids, formaldehyde, amino-alcohols or aminocarboxylic acids. Polycarbonate polyols which may be used include products obtained by reacting diols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol or ter-aethylene glycol with diaryl carbonates, for example diphenyl carbonate, or with phosgene. Polyacetal polyols which may be used include those prepared by reacting glycols such as diethylene glycol, triethylene glycol orhexanediol with formaldehyde. Suitable polyacetals may also be prepared by polymerising cyclic acetals. Suitable polyolefin polyols include hydroxy-terminated butadiene homo- and copolymers and suitable polysiloxane polyols include polydimethylsiloxane diols.
 Mixtures of the aforementioned other isocyanate-reactive compounds may be used
as well. Preferably the other isocyanate-reactive compounds are polyols selected from
the above preferred ones.
 The polyols may comprise dispersions or solutions of addition or condensation
polymers in polyols of the types described above. Such modified polyols, often referred to as "polymer polyols" have been fully described in the prior art and include products obtained by the in situ polymerisation of one or more vinyl monomers, for example styrene and/or acrylonitrile, in the above polyether polyols, or by the in situ reaction between a polyisocyanate and an amino- and/or hydroxy-functional compound, such as triethanolamine, in the above polyol. PolyoxyaBcylene polyols containing from 1 to 50% of dispersed polymer are particularly useful. Particle sizes of the dispersed polymer of less than 50 microns are preferred.
 Still further the following optional ingredients may be used: catalysts enhancing the
formation of urethane bonds like tin catalysts like tin octoate and dibutyltindilaurate, tertiary amine catalysts like triethylenediamine and imidazoles like dimethylimidazole and other catalysts like maleate esters and acetate esters; surfactants; foam stabilisers like siloxane-oxyalkylene copolymers; fire retardants; smoke suppressants; UV-stabilizers; colorants; microbial inhibitors; organic and inorganic fillers, impact modifiers, plasticizers and internal mould release agents. Further external mould release agents may be used in the process according to the present invention.
 Any compound that catalyses the isocyanate trimerisation reaction
(isocyanurate-formation) can be used as trimerisation catalyst in the process according to the present invention, such as tertiary amines, triazines and most preferably metal salt trimerisation catalysts.
[030 ] Examples of suitable metal salt trimerisation catalysts are alkali metal salts of
organic carboxylic acids. Preferred alkali metals are potassium and sodium, and preferred carboxylic acids are acetic acid and 2-ethylhexanoic acid.
 Most preferred metal salt trimerisation catalysts are potassium acetate
(commercially available as Polycat 46 from Air Products and Catalyst LB from Huntsman Polyurethanes) and potassium 2-ethylhexanoate (commercially available as Dabco K15 from Air Products). Two or more different metal salt trimerisation catalysts can be used in the process of the present invention.
 The metal salt trimerisation catalyst is generally used in an amount of up to 5% by weight based on the isocyanate-reactive composition, preferably 0.1 to 3% by weight. It may occur that the polyol used in die process according to the present invention still contains metal salt from its preparation which may then be used as the trimerisation catalyst or as part of the trimerisation catalyst.
 The polyurethane material may be a solid or blown (microcellular) material. Mi-
crocellular materials are obtained by conducting the reaction in the presence of a blowing agent, like hydrocarbons, hydrofluorocarbons, hydiochlorofhioro-carbons, gases like N^ and CO , and water. Most preferably water is used as the blowing agent. The amount of blowing agent will depend on the desired density. The amount of water
will be less than 5, preferably less than 3 and most preferably less than 1% by weight; calculated on the weight of the isocyanate-reactive composition. Density reduction may also be achieved by the incorporation of expanded or expandable microspheres like Expancel or hollow glass microbeads.
 The reaction to prepare the material is conducted at an NCO index of 150-1500.
 The density of the materials is higher than 100 kg/m3'
 The materials are preferably made in a mould. The process may be conducted in
any type of mould known in the art. Examples of such moulds are the moulds com
mercially used for making shoe parts like soccer shoes arid ski- and skate boots,
automotive parts, like arm-rests, door panels and back-shelves. Preferably the reaction
is conducted in a closed mould. The ingredients used for making the material are fed
into the mould at a temperature of from ambient temperature up to 80°C, the mould
being kept at a temperature of from ambient temperature up to 150°C during the
process. Demoulding time is relatively short despite the fact that preferably no
isocyanate-reactive compounds, containing reactive amine groups, are used; depending
on the amount of catalyst demould times may be below 10 minutes, preferably below 5
minutes, more preferably below 3 minutes and most preferably below 1 minute.
 The moulding process may be conducted according to the reaction injection
moulding (RIM) process and the cast moulding process. The process may also be conducted according to the RRIM (reinforced RIM) and SRIM (structural RIM) process.
 In general, the isocyanate-reactive ingredients and catalysts may be pre-mixed,
optionally together with the optional ingredients, before being brought into contact with the polyisocyanate.
 The materials according to the invention are particularly suitable for use in ap-
plications where high stiffness, non-brittle, high impact resistant and low density
materials are desirable, like soccer shoe soles and ski-boots, and automotive parts like
arm-rests, doorpanels, back-shelves and sun visors.
 The present invention is illustrated by the following examples.
 Examples 1 - 4
 Suprasec 2020 and Daltocel F526 were dispensed into a mould (dispensing
machine Krauss Maffei Comet 2020 high pressure piston machine, output was 300g/s). The mould was a steel mould having dimensions 30x60x0.3 cm and mounted in a Battenfeld press.
 The temperature of the chemicals and of the mould was 35 and 85°C, respectively.
Before use, the mould was treated with Acmos 35-5015 mould release agent. Demould ime was 60 seconds. The amounts (in parts by weight) used and the physical properties of the polyisocyanurate polyurethane parts are given in below table.
* A uretonimine/carbodiimide-modified 4,4"-MDI having an NCO-content of 293% by weight and a uretonimine/carbodiimide content of about 27% by weight obtainable from Huntsman Polyurethanes. Suprasec is a trademark of Huntsman International LLC.
046** A glycerol-initiated polyoxyethylene polyol having an OH-value of 140 mg KOH/g obtainable from Huntsman Polyurethanes. Daltocel is a trademark of Huntsman International LLC.
*** mixed in Daltocel F526.
**** Daltocel F526 contains enough Na/K-salt catalyst from its production; no additional catalyst needed.
1. A process for preparing a polyisocyanurate polyurethane material, which process
comprises reacting a polyisocyanate consisting of:
a) 80-100% by weight of diphenylmethane diisocyanate comprising at least 40% by weight of 4,4'-diphenylmethane diisocyanate and/or a variant of said diphenylmethane diisocyanate which variant is liquid at 25°C and has an isocyanate value of at least 20% by weight (polyisocyanate a), and
b) 20-0%o by weight of another polyisocyanate (polyisocyanate b) chosen from aliphatic, cycloaliphatic, araliphatic and aromatic polyisocyanates,
and an isocyanate-reactive composition consisting of,
a) 80-100% by weight of a polyether polyol of the kind such as herein described having an average nominal functionality of 2-6, an average equivalent weight of 150-1000, an average molecular weight of 600-5000, an oxyethylene (EO) content of 75-100% by weight, and
b) 20-0% by weight of one or more other isocyanate-reactive compounds selected from chain extenders, cross-linkers, polyether polyamines, polyester polyols and polyether polyols having a molecular weight of more than 500, wherein the reaction is conducted at an isocyanate index of 150 to 1500 and in the presence of a trimerisation catalyst, wherein said catalyst is selected from tertiary amines, triazines and metal salt trimerization catalysts.
2. A polyisocyanurate polyurethane material made according to the process as claimed
in claim 1.
|Indian Patent Application Number||4775/DELNP/2005|
|PG Journal Number||33/2010|
|Date of Filing||19-Oct-2005|
|Name of Patentee||HUNTSMAN INTERNATIONAL LLC.|
|Applicant Address||500 HUNTSMAN WAY, SALT LAKE CITY, UTAH 84108, U.S.A.|
|PCT International Classification Number||C08G 18/09|
|PCT International Application Number||PCT/EP2004/050898|
|PCT International Filing date||2004-05-24|