GB1585901A - Process for the production of cold setting flexible foams which contain urethane groups - Google Patents

Abstract

Cold-curing, flexible foams containing urethane groups are prepared by reacting polyethers containing at least two hydroxyl groups and having a molecular weight of from 400 to 10,000, in which at least 10% by weight of the hydroxyl groups present are primary hydroxyl groups, with a mixture of diphenylmethane diisocyanates and oligomeric polyphenyl-polymethylene polyisocyanates in the presence of blowing agents and optionally in the presence of catalysts and further foaming auxiliaries. Polyesters containing 2-8 hydroxyl groups, primary hydroxyl group-free polyethers, polythioethers, polyacetals, polycarbonates and polyester-amides having a molecular weight of 400-10,000 can optionally be included in the reaction in amounts of up to 50% by weight, based on the polyethers. These foams are obtained by employing a mixture of diphenylmethane diisocyanates and oligomeric polyphenyl-polymethylene polyisocyanates which contains 60-90% by weight of 4,4'-diphenylmethane diisocyanate and 3-30% by weight of 2,4'-diphenylmethane diisocyanate.

Description

(54) PROCESS FOR THE PRODUCTION OF COLD SETTING FLEXIBLE FOAMS WHICH CONTAIN URETHANE GROUPS (71) We, BAYER AKTIENGESELLSCHAFT, a body corporate organised under the Laws of Germany of 509 Leverkusen, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: It is well known that foams which contain urethane groups are widely used, for example in the field of insulation, for the manufacture of structural elements and for upholstery purposes.

It is also known that cold setting foams which contain urethane groups can be produced from higher molecular weight polyols such as hydroxyl polyethers, special polyisocyanates, water and/or other blowing agents, optionally in the presence of catalysts and other auxiliary agents.

The higher molecular weight polyols used are frequently polyethers, for example with a molecular weight of 400-10,000, which contain at least two hydroxyl groups and in which at least about 10% of the hydroxyl groups are primary hydroxyl groups, these polyethers being used, for example, in combination with special polyisocyanates.

The special isocyanates used may be, for example, a mixture of diphenyl methane diisocyanates and polyphenyl-polymethylene polyisocyanates.

The previously known cold setting foams based on polyphenyl-polymethylene polyisocyanates, for example those described in German Offenlegungsschrift No. 2,425,657, (Examples 1-5) have the following serious disadvantage, which is particularly disturbing when the foams are produced inside moulds; even when the reaction mixture has been inside the mould for about 10 minutes, the foams formed during this time are still irreversibly deformable. Although this tendency to deformation can be overcome by storage of the reaction mixture for about 24 hours or by subsequent heating of the foams lafter their removal from the mould, for about thirty minutes at 1200C, it is always a disadvantageous characteristic. Furthermore, moulding times of less than five minutes cannot be achieved according to German Offenlegungsschrift No. 2,525,657.

An improved process for the production of cold setting, flexible foams which contain urethane groups has now been found.

This process reduces or substantially obviates the disadvantages described above and is based on the use of a certain mixture of diphenyl methane diisocyanates and oligomer polyphenyl-polymethylene polyisocyanates.

The present invention thus relates to a process for the production of a cold setting, flexible foam which contains methane groups and which does not have an integral skin, which comprises reacting a polyether with a molecular weight of 400 to 10,000 which contains at least two hydroxyl groups and in which at least 10% by weight of the hydroxyl groups are primary hydroxyl groups with a mixture of diphenyl methane diisocyanates and ligomer polyphenyl-polymethylene polyisocyanate in the presence of a blowing agent and optionally in the presence of a catalyst and other foaming aids, characterised in that the mixture of diphenyl methane diisocyanates and oligomer polyphenyl-polymethylene polyisocyanate contains 6090% by weight, preferably 65-80% by weight of 4,41-diphenylmethane diisocyanates and 3--30C7, by weight, preferably 130% by weight of 2,41-diphenylmethane diisocyanate, and is free from carbodiimide groups.

The isocyanate mixture used according to the invention preferably contains 10 to 25% by weight, more preferably 10 to 20% by weight, of 2,41-diphenylmethane diisocyanate.

The invention has surprisingly been found to show the following practical advantages: 1. Due to the very rapid hardening of these foam systems, moulding times of between 3 minutes and less than 1 minute can be obtained.

2. The rapid hardening substantially re duces the tendency of the foam to de formation, so that any intermediate storage time can be considerably re duced. Reheating of the moulded articles after removal from the mould is no longer necessary. The foams can be packaged after 10 minutes without risk of deformation.

The polyisocyanate mixture used according to the invention is known in the art.

In addition to the polyisocyanate mixture used according to the invention, other isocyanates may be used as starting materials in quantities of up to 20% by weight, based on the quantity of polyisocyanate mixture used according to the invention. These additional, optional, isocyanates include aliphatic, cycloaliphatic and other aromatic and heterocyclic polyisocyanates such as those described, for example, by W. Siefken in Justus Liebigs Annalen der Chemie 562, pages 75 to 136, for example ethylene diisocyanate; 1 ,4-tetramethylene diisocyanate; 1,6-hexamethylene diisocyanate; 1,12-dodecane diisocyanate; cyclobutane-l ,3-diisocyanate; cyclohexane-1,3- and -1,4-diisocyanate and any mixtures of these isomers; 1 - isocyanato - 3,3,5 - trimethyl - S - iso- cyanatomethyl-cyclohexane as described in German Auslegesschrift No. 1,202,785 and U.S. Patent Specification No. 3,401,190; 2,4- and 2,6-hexahydrotolylene diisocyanate and any mixtures of these isomers; hexahydro-1,3- and/or -1,4-phenylene diisocyanate; perhydro-2,41- and/or -4,41-diphenylmethane diisocyanate; 1,3- and 1,4phenylene diisocyanate; 2,4- and 2,6-tolyene diisocyanate and any mixtures of these isomers; naphthylene-1,5-diisocyanate: triphenylmethane - 4,41,411 - triisocyanate; mand p-isocyanatophenylsulphonyl isocyanate according to U.S. Patent Specification No. 3,454,606; perchlorinated aryl polyisocyanates as described, for example, in German Auslegeschrift No. 1,157,601 and U.S.

Patent Specification No. 3,277,138; polyisocyanates having carbodiimide groups as described in German Patent Specification No. 1,092,007 and U.S. Patent Specification No. 3,152,162; the diisocyanates described in U.S. Patent Specification No. 3,492,330; polyisocyanates having allophanate groups as described e.g. in British Patent Specification No. 994,890; Belgian Patent Specification No. 761,626 and published Dutch Patent Application No. 7,102,524; polyisocyanates having isocyanurate groups as described, for example, in U.S. Patent Specification No. 3,001,973; German Patent Specifications Nos. 1,022,789; 1,222,067 and 1,027,394 and in German Offenlegungsschriften Nos. 1,929,034 and 2,004,048; polyisocyanates having urethane groups, e.g. as described in Belgian Patent Specification No. 752,261 or in U.S. Patent Specification No. 3,394,164; polyisocyanates having acylated urea groups according to German Patent Specification No.

1,230,778; polyisocyanates having biuret groups, e.g. as described in German Patent Specification No. 1,101,394; U.S. Patent Specification Nos. 3,124,605 and 3,201,372; and in British Patent Specification No.

889,050; polyisocyanates prepared by telomerisation reactions as described, for example in U.S. Patent Specification No.

3,654,106; polyisocyanates with ester groups, e.g. those mentioned in British Patent Specifications Nos. 965,474 and 1,072,956; U.S. Patent Specification No.

3,567,763 and German Patent Specification No. 1,231,688; reaction products of the above mentioned isocyanates with acetals according to German Patent Specification No. 1,072,385 and polyisocyanates containing polymeric fatty acid groups according to U.S. Patent Specification No. 3,455,883.

The distillation residues obtained from the commercial production of isocyanates and still containing isocyanate groups may also be used, if desired as solutions in one or more of the above mentioned polyisocyanates. Any mixtures of the above mentioned polyisocyanates may be used.

Monofunctional isocyanates such as propyl isocyanate, cyclohexyl isocanäte, phenyl isocyanate, tolyl isocyanate and pchlorophenyl isocyanate may also be included.

Po]yethers containing at least two hy droxyl groups and having a molecular weight of from 400 to 10,000 are also used as a starting component according to the invention, particularly polyethers containing from 2-8, preferably 2 hydroxyl groups and especially those with a molecular weight of from 800 to 10,000, preferably 1,000 to 6,000; at least 10% by weight of the hydroxyl groups in these polyethers are primary hydroxyl groups: These polyethers are known per se and may be prepared, for example, by the polymerisation of epoxides such as ethylene oxide and optionally propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin, each on their own, e.g. in the presence of boron trifluoride, or by addition of these epoxides, either as mixtures or successively, to starting components with reactive hydrogen atoms, such as water, alcohols, ammonia or amines, e.g. ethylene glycol; propylene glycol-(1,3) or -(1,2); trimethylolpropane; glycerol; 4,41-dihydroxydiphenylpropane; aniline, ethanolamine or ethylenediamine. In these polyethers, the primary hydroxyl (end) groups are prefer- ably formed by the reaction of ethylene oxide. Sucrose polyethers may also be used according to the invention for example those described in German Auslegeschriften Nos. 1,176,358 and 1,064,938. Polyethers modified by vinyl polymers, for example the compounds obtained by the polymerisation of styrene and acrylonitrile in the presence of polyethers as described in U.S. Patent Specification Nos. 3,383,351; 3,304,273; 3,523,093 and 3,110,695 and German Patent Specification No. 1,152,536 are also suitable.

The starting components which may be used according to the invention in addition to the polyethers containing primary hydroxyl groups in quantities of up to 50% by weight, based on the polyethers, also include hydroxyl polyesters, hydroxyl polyethers which are free from primary hydroxyl groups, hydroxyl polythioethers, hydroxyl polyacetals, hydroxyl polycarbonates, hydroxyl polyester amides, and polybutadienes which contain hydroxyl groups, all of which are known per se for the production of both homogeneous and cellular polyurethanes.

These hydroxyl polymers contain at least two hydroxyl groups, generally 2 to 8, preferably 2 to 4 hydroxyl groups and they generally have a molecular weight of from 400 to 10,000, preferably 800 to 10,000 and most preferably 1,000 to 6,000.

Suitable polyesters with hydroxyl groups include, for example, the reaction products of polyhydric, preferably dihydric alcohols to which trihydric alcohols, may be added and polybasic, preferably dibasic carboxylic acids. Instead of free polycarboxylic acids the corresponding polycarboxylic acid esters of lower alcohols or mixtures thereof may be used for preparing the polyesters. The polycarboxylic acids may be aliphatic, cycloaliphatic, aromatic and/or heterocyclic and they may be substituted, e.g. by halogen atoms and/or unsaturated.

The following are mentioned as examples: Succinic acid; adipic acid; suberic acid; azelaic acid; sebacic acid; phthalic acid; isophthalic acid; trimellitic acid; phthalic acid anhydride; tetrahydrophthalic acid anhydride; hexahydrophthalic acid anhydride; tetrachlorophthalic acid anhydride; endomethylene tetrahydrophthalic acid anhydride; glutaric acid anhydride; maleic acid; maleic acid anhydride; fumaric acid; dimeric and trimeric fatty acids such as oleic acid which may be mixed with monomeric fatty acids; dimethyl terephthalate and terephthalic acid-bis-glycol esters. The following are examples of suitable polyvalent alcohols: Ethylene glycol, propylene glycol (1,2) and -(1,3); butylene glycol-(1,4) and -(2,3); hexanediol-1,6); octanediol-1,8); neopentylglycol; cyclohexanedimethanol (1,4 - bis - hydroxymethylcyclohexane); 2methyl-1,3-propanediol; glycerol; trimethylolpropane; hexanetriol-1,2,6); butanetriol (1,2,4); trimethylolethane; pentaerythritol; quinitol; mannitol and sorbitol; methylglycoside; diethylene glycol; triethylene glycol; tetraethylene glycol; polyethylene glycols; dipropylene glycol; polypropylene glycols; dibutylene glycol and polybutylene glycols.

The polyesters may also contain a proportion of carboxyl end groups. Polyesters of lactones such as c-caprolactone or hydroxycarboxylic acids such as > Z-hydroxycaproic acid may also be used.

The polyethers which may be used according to the invention which have at least 2, generally 2 to 8 and preferably 2 to 3 hydroxyl groups (but not primary hydroxyl groups) are also known per se and are prepared, for example, by polymerisation of epoxides such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin, either each on its own, e.g. in the presence of boron trifluoride, or by addition of these epoxides, either as mixtures or successively, to starting components having reactive hydrogen atoms, such as water, alcohols, ammonia or amines, e.g. ethylene glycol, propylene glycol-(1,3) or -(1,2), trimethylolpropane, 4,41-dihydroxy diphenylpropane, aniline, ethanolamine or ethylene diamine. Sucrose polyethers may also be used according to the invention, e.g. those described in German Auslegeschriften No.

1,176,358 and No. 1,064,938. All these polyethers are free from primary hydroxyl groups.

Particularly to be mentioned among the polythioethers are the condensation products obtained by reacting thiodiglycol on its own and/or with other glycols, dicari- oxylic acids, formaldehyde, aminocarboxylic acids or amino alcohols. The products ob tained are polythio mixed ethers, polythio ether esters or polythio ether ester amides, depending on the cocomponents.

Suitable polyacetals include, for example, the compounds which can be prepared from glycols, such as diethylene glycol, triethylene glycol, 4.41-dioxethoxydiphenyl dimethylmethane, and hexanediol, and formaldehyde.

Suitable polyacetals for the purpose of the invention may also be prepared by the polymerisation of cyclic acetals.

Suitable polycarbonates with hydroxyl groups may be of the kind known per se, for example those which can be prepared by the reaction of diols such as propanediol-(1,3), butanediol-(1,4) and/or hexane diol-(1,6), diethylene glycol, triethylene glycol or tetraethylene glycol with diarylcarbonates, e.g. with diphenylcarbonate or phosgene.

Suitable polyester amides and polyamides include, for example, the predominantly linear condensates prepared from polyvalent saturated and unsaturated carboxylic acids or their anhydrides and polyvalent saturated and unsaturated amino alcohols, diamines, polyamines and mixtures thereof.

Polyhydroxyl compounds already containing urethane or urea groups and modified or unmodified natural polyols such as castor oil, carbohydrates, e.g. starch may also be used. Addition products of alkylene oxides and phenol formaldehyde resins or of alkylene oxides and urea formaldehyde resins are also suitable for the purpose of the invention.

Representatives of these compounds which may be used according to the invention have been described, for example, in High Polymers, Vol. XVI, "Polyurethanes, Chemistry and Technology" by Saunders Frisch, Interscience Publishers, New York, London, Volume I, 1962, pages 32--42 and pages 4445 and Volume II, 1964, pages 5-6 and 198-199 and in Kunststoff Hundbuch, Volume VII, Vieweg-Hochtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 45 to 71.

Mixtures of the above mentioned compounds which contain at least two hydrogen atoms capable of reacting with isocyanates and have a molecular weight of from 400 to 10,000 may, of course, also be used, for example mixtures of polyethers and polyesters.

The starting components used according to the invention may also include compounds with a molecular weight of from 32 to 400 which have at least two hydrogen atoms capable of reacting with isocyanates in amounts of up to 50% b.w., based on the polyethers containing primary hydroxyl groups. These also are compounds containing hydroxyl groups and/or amino groups and/or thiol groups and/or carboxyl groups, preferably hydroxyl groups and/or amino groups, and they serve as chain-lengthening agents or cross-liking agents. They generally have from 2 to 8 hydrogen atoms capable of reacting with isocyanates, preferably 2 or 3 such hydrogen atoms. The following are examples of such compounds: Ethylene glycol, propylene glycol-(1,2) and -(1,3), butylene glycol-(1,4) and -(2,3); pentanediol (1,5); hexanediol-(1,6); octanediol-(1,8); neopentyl glycol; 1 4-bis-hydroxymethyl- cyclohexane; 2-methyl-1,3-propanediol; glycerol; trimethylol profane; hexanetriol (1,2,6); trimethylolethane; pentaerythritol; quinitol; mannitol and sorbitol; diethylene glycol; triethylene glycol; tetraethylene glycol; polyethylene glycols with a molecular weight of up to 400; dipropylene glycol; polypropylene glycols with a molecular weight of up to 400; dibutylene glycol; polybutylene glycols with a molecular weight of up to 400; 4,41-dihydroxy-diphenyl propane; dihydroxymethyl-hydroquinone; ethanolamine; diethanolamine; triethanolamine; 3-aminopropanol; ethylene diamine; 1 ,3-diaminopropane; 1 -mercapto-3 -amino- propane; 4-hydroxyphthalic acid; 4-aminophthalic acid; succinic acid; adipic acid; hydrazine; N,N-dimethylhydrazine; 4,41di- aminodiphenylmethane; tolylenediamine; methylene-bis-chloraniline; methylene-bisanthranilic acid ester; diaminobenzoic acid esters and the isomeric chlorophenylene diamines.

In this case again there may be used mixtures of various compounds having a molecular weight of from 32 to 400 and containing at least two hydrogen atoms capable of reacting with isocyanates.

According to the invention, polyhydroxyl compounds in which high molecular weight polyadducts or polycondensates are finely dispersed or dissolved may also be used in quantities of up to 50% b.w., based on the polyethers containing primary hydroxyl groups. These modified polyhydroxyl compounds are obtained when polyaddition reactions, e.g. reactions between polyisocyanates and amino functional compounds, or polycondensation reactions, e.g. between formaldehyde and phenols and/or amines, are carried out in situ in the above mentioned hydroxyl compounds. Processes of this kind have been described, for example, in German Auslegeschriften Nos. 1,168,075 and 1,260,142 and in German Offenlegungsschriften Nos. 2,324,134; 2,423,984; 2,512,385; 2,513,185; 2,550,796; 2,550,797; 2,550.833 and 2,550,862. Alternatively, these modified polyhydroxyl compounds may be obtained according to U.S. Patent No.

3,869,413 or German Offenlegungsschrift No. 2,550,860 by mixing a previously prepared aqueous polymer dispersion with a polyhydroxyl compound and then removing the water from the mixture.

According to the invention, water and/or readily volatile organic substances are used as blowing agents. Suitable organic blowing agents include, for example, acetone, ethyl acetate and halogen substituted alkanes such as methylene chloride, chloroform, ethylidene chloride, monofluorotrichloromethane, eblorodifluoromethane, and dichlorodifluoromethane as well as vinylidene chloride, butane, hexane, heptane and diethyl ether.

The effect of a blowing agent can also be obtained by the addition of compounds which decompose at temperatures above room temperature to release gases such as nitrogen, e.g. azo compounds such as azoisobutyric acid nitrile. Further examples of blowing agents and the use of blowing agents have been described in Kunststoff Handbuch, Volume VII, published by Vieweg and Hochtlen, Carl-Hanser-Verlag, Munich 1966, e.g. on pages 108 and 109, 453 to 455 land 507 to 510.

Catalysts are also frequently used according to the invention. The catalysts added may be known per se, for example tertiary amines such as triethylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, N-cocomorpholine, N,N,N1,N1-tetramethyl- ethylenediamine, 1 ,4-diaza-bicyclo-(2,2,2)- octane, N-methyl-N1-dimethylaminoethylpiperazine, N,N-dimethylbenzylamine, bis (N,N-diethyl-aminoethyl)-adipate, N,N-di- ethylbenzylamine, pentamethyldiethylenetriamine, N,N-dimethylcyclohexylamine, N,N,N1,N1 - tetramethyl - 1,3 - butanediamine, N,N-dimethyl-lS-phenylethylamine, 1,2-dimethylimidazole and 2-methylimidazole. Mannich bases known per. se obtained from secondary amines such as dimethylamine and aldehydes, preferably formaldehyde, or ketones such as acetone, methyl ethyl ketone or cyclohexanone and phenols such as phenol, nonylphenol or bisphenol may also be used as catalysts.

Examples of catalysts which consist of tertiary amines having hydrogen atoms which are reactive with isocyanate groups include triethanolamine, triisopropanolamine, N-methyl-diethanolamine, N-ethyldiethanolamine, N,N-dimethyl-ethanolamine and their reaction products with alkylene oxides such as propylene oxide and/or ethylene oxide.

Silaamines having carbon-silicon bonds as described e.g. in German Patent-Specifica- tion No. 1,229,290 corresponding to U.S.

Patent Specification No. 3,620,984 may also be used as catalysts, e.g. 2,2,4-trimethyl-2silamorpholine or 1,3-diethylaminoethyl tetramethyldisiloxane.

Basic nitrogen compounds huch as tetra alkylammonium hydroxides, alkali metal hydroxides such as sodium hydroxide, alkali metal phenolates such as sodium phenolate and alkali metal alcoholates such as sodium methylate may also be used as catalysts.

Hexahydrotriazines are also. suitable cata lysts.

Organic metal compounds may also be used as catalysts according to the invention, in particular organic tin compounds.

The organic tin compounds used are pre ferably tin(II) salts of carboxylic acids such as tin(II) aectate, tin(II) octoate, tin(II) ethyl hexoate and tin(II) laurate and tin(IV) com pounds such as dibutyl tin oxide, dibutyl tin dichloride, dibutyl tin diacetate, dibutyl tin dilaurate, dibutyl tin maleate or dioctyl tin diacetate. All the above mentioned cata lysts may, of course, be used as mixtures.

Further examples of catalysts which may be used according to the invention and de tails concerning the activity of the catalysts are given in Kunststoff-Handbuch, Volume VII, published by Vieweg and Hochilen.

Clarl-Hanser-Verlag, Munich 1966, e.g. on pages 96 to 102.

The catalysts are generally used in a quantity of between about 0.001 and 10 by weight, based on the quantity of poly ethers used according to the invention, which have a molecular weight of from 400 to 10,000.

Surface active additives such as emulsi fiers and foam stabilisers may also be used according to the invention. Suitable emulsi fiers include e.g. the sodium salts of ricin oleic sulphonates or salts of fatty acids with amines such as oleic acid diethylamine or stearic acid diethanolamine. Alkali metal or ammonium salts of sulphonic acids such as dodecylbenzene sulphonic acid or di naphthylmethane disulphonic acid or of fatty acids such as ricinoleic acid or of polymeric fatty acids may also be used as surface active additives.

Polyether siloxanes are particularly suit able foam stabilizers, especially those which are water soluble. These compounds gener ally have a polydimethyl siloxane group attached to a copolymer of ethylene oxide and propylene oxide. Foam stabilizers of this kind have been described, for example in U.S. Patent Specifications Nos. 2,834,748; 2,917,480 and 3,629,308.

It may, however, be advantageous to carry out the process according to the in vention without foam stabilizers.

Other additives which may also be used according to the invention include reaction retarders, e.g. substances which are acid in reaction such as hydrochloric acid or organic acid halides, cell regulators known per se such as paraffins or fatty alcohols or dimethyl polysiloxanes, pigments, dyes, flame retarding agents known per se such as tris chloroethyl phosphate, tricresyl phosphate or ammonium phosphate and polyphos phates, stabilizers against ageing and weathering, plasticizers, fungistatic and bacteriostatic substances and fillers such as barium sulphate, kieselguhr, carbon black or whiting.

Other examples of surface active additives, foam stabilizers, cell regulators, reaction rearders, stabilizers, flame retarding substances, plasticizers, dyes, fillers, and fungistatic and bacteriostatic substances which may be used according to the invention and details concerning the use and mode of action of these additives may be found in Kunststoff-Handbuch, Volume VII, published by Vieweg and Hochtlen, Carl-Hanser Verlag, Munich 1966, e.g. on pages 103 to 113.

According to the invention, the components may be reacted together by the known one-shot, prepolymer or semiprepolymer process, often using mechanical devices such as those described in U.S.

Patent Specification No. 2,764,565. Details concerning processing apparatus which may also be used according to the invention may be found in Kunststoff-Handbuch, Volume VII, published by Vieweg and Hochtlen, Carl-Hanser-Verlag, Munich 1966, e.g. on pages 121 and 205.

According to the invention, the foaming reaction for producing foam products is often carried out inside moulds. In this process, the foamable reaction mixture is introduced into a mould which may be made of a metal such as aluminium or a plastics material such as an epoxide resin, and it foams up inside the mould to produce the shaped product. The process of foaming in moulds may be carried out to produce a product having a cellular structure on its surface. According to the invention, the desired result can be obtained by introducing just sufficient foamable reaction mixture to fill the mould with foam after the reaction.

So-called external mould release agents known per se, such as silicone oils, are frequently used when foaming is carried out inside moulds but the process may also be carried out with the aid of so-called internal mould release agents, if desired in combination with external mould release agents, e.g.

as disclosed in German Offenlegungsschriften No. 2,121,670 and No. 2,307,589.

Cold setting foams may also be produced according to the invention as described in British Patent Specification No. 1,162,517 and German Offenlegungsschrift No.

2,153,086.

Foams may, of course, also be produced by the process of block foaming or by the laminator process known per se.

The products obtainable according to the invention may be used, for example, as up- holstery or padding materials.

EXAMPLE 1 (comparison example) (A) 100 parts by weight of a polypropylene glycol which had been started on trimethylolpropane and modified with ethylene oxide to result in a hydroxyl number of 28 with 80% of primary hydroxyl end groups, 3.2 parts by weight of water, 0.15 parts by weight of diazabicyclo 2,2,2-octane, 0.10 parts by weight of 2,21-dimethyl aminodiethylether, and 5 parts by weight of trichlorofluoro methane and (B) 54,8 parts by weight of a polyisocyanate mixture consisting of 34% by weight of 2,41-diphenylmeth ane diisocyanate, 51% by weight of 4,41-diphenylmeth ane diisocyanate, and 15% by weight of oligomer polyphenyl polymethylene polyisocyanate were reacted together in a closed mould.

Mould release time: 8 minutes.

A moulded foam product having the following mechanical properties is obtained: Gross density ... DIN 53420 (kg/m3) 44 Tensile test ... ... ... DIN 53571 (KPa) 130 Elongation at break ... DIN 53571 (tO) 150 Compression test . DIN 53577 (KPa) 5.4 EXAMPLE 2 (A) 100 parts by weight of a polypropylene glycol which had been started on trimethylolpropane and modified with ethylene oxide to result in a hydroxyl number of 28 and 85% of primary hydroxyl end groups, 2.7 parts by weight of water, 0.33 parts by weight of diazabicyclo 2,2,2-octane, 0.1 parts by weight of 2,21-dimethyl aminodiethylether, 0.5 parts by weight of N-methyl morpholine, 0.02 parts by weight of dibutyl tindi laurate, 1.5 parts by weight of glycerol, and 8 parts by weight of trichlorofluoro methane and (B) 54.0 parts by weight of a polyisocyanate mixture consisting of 5% by weight of 2,41-diphenylmethane diisocyanate, 80% by weight of 4,41-diphenylmeth ane diisocyanate, and 150Jo by weight of oligomer polyphenyl polymethylene polyisocyanate are reacted together in a closed mould.

Mould release time: 1 minute.

A moulded flexible foam product having the following mechanical properties is obtained: Gross density ... DIN 53420 (kg/m3) 43 Tensile test ... ... ... DIN 53571 (KPa) 105 Elongation at break ... DIN 53571 (%) 130 Compression test . MN DIN 53577 (KPa) 5.8 EXAMPLE 3 (A) 100 parts by weight of a polypropylene glycol which has been started on tri methylolpropane and modified with ethylene oxide to result in 75% of primary hydroxyl end groups and a hydroxyl number of 35, 2.7 parts by weight of water, 0.33 parts by weight of diazabicyclo 2,2,2-octane, 0.06 parts by weight of 2,21-dimethyl amino diethylether, 0.5 parts by weight of N-methyl morpholine, 0.2 parts by weight of dibutyl tindi laurate, 1.5 parts by weight of glycerol, and 8 parts by weight of trichJorofluoro- methane, and (B) 50.4 parts by weight of a polyisocyanate mixture consisting of 10% by weight of 2,41-diphenylmethane diisocyanate, 75% by weight of 4,41-diphenylmethane diisocyanate, and 15% by weight of oligomer polyphenyl polymethylene polyisocyanate and containing 20% by weight of tolylene diisocyanate (2,4-: 2,6-isomer as 80:20% by weight) are reacted together in a closed mould.

Mould release time: 1 minute 30 seconds.

A moulded flexible foam product having the following mechanical properties is obtained: Gross density ... ... DIN 53420 (kg/m3) 42.5 Tensile test ... ... DIN 53571 (KPa) 85 Elongation at break . DIN 53571 (%) 145 Compression test . . DIN 53577 (KPa) 4.7 EXAMPLE 4 (A) 100 parts by weight of a polypropylene glycol which has been started on glycerol and modified with ethylene oxide to result in 80% of primary hydroxyl end groups and a hydroxyl number of 28, 3.0 parts by weight of water, 0.55 parts by weight of diazabicyclo 2,2,2-octane, 0.06 parts by weight of 2,21-dimethyl aminodiethylether, and 5 parts by weight of trichlorofluoro methane and (B) 51.75 parts by weight of a polyisocyanate mixture consisting of 26% by weight of 2,41-diphenylmethane diisocyanate, 64% by weight of 4,4'-diphenylmeth ane diisocyanate, and 10% by weight of oligomer polyphenyl polymethylene polyisocyanate are reacted together in a closed mould.

-Mould release time 2 minutes 30 seconds.

A moulded flexible foam product having the following mechanical properties is obtained: Gross density ... ... DIN 53420 (kg/m3) 56 Tensile test DIN ... DIN 53571 (KPa) 200 Elongation at break ... DIN 53571 (%) 185 Compression test ... ... DIN 53577 (KPa) 6.8 When the same reaction mixture is left to foam up without restriction the resulting foam has the following mechanical properties: Gross density DIN ... DM 53420 (kg/m3) 44 Tensile test ... DIN ... DM 53571 (KPa) 110 Elongation at break ... DIN 53571 (%) 180 Compression test ... ... DIN 53577 (KPa) 3.2 EXAMPLE 5 (A) 100 parts by weight of a polypropylene glycol which has been started on trimethylolpropane and modified with ethylene oxide to result in 80% of primary hydroxyl end groups and a hydroxyl number of 28, 2.7 parts by weight of water, 0.20 parts by weight of diazabicyclo 2,2,2-octane, 0.06 parts by weight of 2,21-dimethyl aminodimethylether, and 5 parts by weight of trichlorofluoro methane and (B) 48.8 parts by weight of a polyisocyanate mixture consisting of 10% by weight of 2,41-diphenylmethane diisocyanate, 60% by weight of 4,41-diphenylmethane diisocyanate, and 30% by weight of oligomer polyphenyl polymethylene polyisocyanate are reacted together in a closed mould.

Mould release time: 2 minutes.

A moulded flexible foam product having the following mechanical properties is obtained: Gross density DIN 53420 (kg/m3) 43 Tensile test ... ... DIN 53571 (KPa) 80 Elongation at break DIN 53571 (%) 105 Compression test . DIN 53577 (KPa) 3.8 EXAMPLE 6 (A) 100 parts by weight of a polypropylene glycol which had been started on trimethylolpropane and modified with ethylene oxide to result in a hydroxyl number of 28 with 60% of primary hydroxyl end groups, 3.0 parts by weight of water, 0.5 parts by weight of diazabicyclo 2,2,2-octane, 0.06 parts by weight of 2,21-dimethyl aminodiethylether, and 5 parts by weight of trichlorofluoro methane and (B) 51.75 parts by weight of a polyisocyanate mixture consisting of 26% by weight of 2,41-diphenylmeth ane diisocyanate, 69% by weight of 4,41-diphenylmeth ane diisocyanate, and 5% by weight of oligomer polyphenyl polymethylene polyisocyanate were reacted together in a closed mould.

Mould release time: 2 minutes 30 seconds.

A moulded flexible foam product having the following mechanical properties is obtained: Gross density DIN 53420 (kg/m3) 51 Tensile test ... ... DIN 53571 (KPa) 205 Elongation at break ... DIN 53571 ( /tO) 215 Compression test . . DIN 53577 (KPa) 5.4 WHAT WE CLAIM IS:- 1. A process for the production of a cold setting, flexible foam which contains urethane groups and which does not have an integral skin which comprises reacting a polyether with a molecular weight of 400 to 10,000 which contains at least two hydroxyl groups and in which at least 10% by weight of the hydroxyl groups are primary hydroxyl groups, with a mixture of diphenyl methanediisocyanates and oligomer polyphenyl-polymethylene polyisocyanate in the presence of a blowing agent and optionally in the presence of a catalyst and other foaming auxiliaries, characterised in that the mixture of diphenyl methane diisocyanates

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   Gross density ... ... DIN 53420 (kg/m3) 56 Tensile test DIN ... DIN 53571 (KPa) 200 Elongation at break ... DIN 53571 (%) 185 Compression test ... ... DIN 53577 (KPa) 6.8 When the same reaction mixture is left to foam up without restriction the resulting foam has the following mechanical properties: Gross density DIN ... DM 53420 (kg/m3) 44 Tensile test ... DIN ... DM 53571 (KPa) 110 Elongation at break ... DIN 53571 (%) 180 Compression test ... ... DIN 53577 (KPa) 3.2 EXAMPLE 5 (A) 100 parts by weight of a polypropylene glycol which has been started on trimethylolpropane and modified with ethylene oxide to result in 80% of primary hydroxyl end groups and a hydroxyl number of 28,

   2.7 parts by weight of water, 0.20 parts by weight of diazabicyclo 2,2,2-octane, 0.06 parts by weight of 2,21-dimethyl aminodimethylether, and 5 parts by weight of trichlorofluoro methane and (B) 48.8 parts by weight of a polyisocyanate mixture consisting of 10% by weight of 2,41-diphenylmethane diisocyanate, 60% by weight of 4,41-diphenylmethane diisocyanate, and 30% by weight of oligomer polyphenyl polymethylene polyisocyanate are reacted together in a closed mould.

   Mould release time: 2 minutes.

   A moulded flexible foam product having the following mechanical properties is obtained: Gross density DIN 53420 (kg/m3) 43 Tensile test ... ... DIN 53571 (KPa) 80 Elongation at break DIN 53571 (%) 105 Compression test . DIN 53577 (KPa) 3.8 EXAMPLE 6 (A) 100 parts by weight of a polypropylene glycol which had been started on trimethylolpropane and modified with ethylene oxide to result in a hydroxyl number of 28 with 60% of primary hydroxyl end groups,

   3.0 parts by weight of water, 0.5 parts by weight of diazabicyclo 2,2,2-octane, 0.06 parts by weight of 2,21-dimethyl aminodiethylether, and 5 parts by weight of trichlorofluoro methane and (B) 51.75 parts by weight of a polyisocyanate mixture consisting of 26% by weight of 2,41-diphenylmeth ane diisocyanate, 69% by weight of 4,41-diphenylmeth ane diisocyanate, and 5% by weight of oligomer polyphenyl polymethylene polyisocyanate were reacted together in a closed mould.

   Mould release time: 2 minutes 30 seconds.

   A moulded flexible foam product having the following mechanical properties is obtained: Gross density DIN 53420 (kg/m3) 51 Tensile test ... ... DIN 53571 (KPa) 205 Elongation at break ... DIN 53571 ( /tO) 215 Compression test . . DIN 53577 (KPa) 5.4 WHAT WE CLAIM IS:- 1. A process for the production of a cold setting, flexible foam which contains urethane groups and which does not have an integral skin which comprises reacting a polyether with a molecular weight of 400 to 10,000 which contains at least two hydroxyl groups and in which at least 10% by weight of the hydroxyl groups are primary hydroxyl groups, with a mixture of diphenyl methanediisocyanates and oligomer polyphenyl-polymethylene polyisocyanate in the presence of a blowing agent and optionally in the presence of a catalyst and other foaming auxiliaries, characterised in that the mixture of diphenyl methane diisocyanates

   and oligomer polyphenyl-polymethylene polyisocyanate contains 6090% by weight, of 4,41-diphenylmethane diisocyanate and 3-30% by weight of 2,41-diphenylmethane diisocyanate and is free from carbodiimide groups.
2. 2. A process as claimed in claim 1 in which the isocyanate mixture contains 65 to 80% by weight of 4,41-diphenylmethane diisocyanate and 10 to 30% by weight of 2,41 diphenylmethane diisocyanate.
3. 3. A process as claimed in claim 1 or claim 2 characterised in that the mixture of diphenylmethane diisocyanates and oligomer polyphenyl - polymethylene - polyisocyanate contains 10-25% by weight of 2,41-diphenylmethane diisocyanate.
4. 4. A process as claimed in claim 3 in which the isocyanate mixture contains 10 to 20% by weight of 2,41-diphenylmethane diisocyanate.
5. 5. A process as claimed in any of claims 1 to 4, characterised in that the reaction is carried out in the absence of foam stabilisers.