Abstract: A method for producing a modified polyisocyanurate foam by reacting an organic polyisocyanate, polyol and water in the presence of a trimerizing catalyst composed of a certain hydroxyalkyl quaternary ammonium compound, and a carbodiimidizing catalyst composed of a certain phosphorene oxide. The method enables production of low density modified polyisocyanurate foams with ease and rapidly without using volatile blowing agents such as CFC, HCFC, HFC and methylene chloride.

Abstract: Polyurethane foams blown with a mixture of water, HCFC-22 or HCFC-141b, and a perfluorinated hydrocarbon having from 3 to 8 carbon atoms yields polyurethane and polyisocyanurate foams having exceptional physical properties, i.e., small and uniform cells, low initial K-factor, low aged K-factor, and high tensile strength. The low initial and aged K-factors are most unexpected when it is considered that significant amounts of water are used to blow the foam.

Abstract: Rigid polyurethane foams having low thermal conductivity values are produced by reacting an organic polyisocyanate with an organic material having at least two isocyanate reactive hydrogen atoms and an OH value of from about 200 to about 650 in the presence of a blowing agent. The blowing agent is a mixture of 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) or dichlorofluoroethane (HCFC-141b) and from about 0.1 to about 1.0% by weight (based on total weight of the foam forming mixture) water. The foams obtained are characterized by a thermal conductivity of less than about 0.130 Btu-in./hr.ft.sup.2.F, preferably less than about 0.120 Btu-in./hr.ft.sup.2.F. These foams are particularly useful as insulation materials.

Abstract: Rigid, closed cell polyisocyanurate foams are prepared by reacting together a polyisocyanate and a polyester polyol or a mixture of a polyester polyol and at least one other isocyanate-reactive compound in the presence of (a) a hydrogen-containing blowing agent or a mixture of a hydrogen-containing blowing agent and at least one co-blowing agent and (b) a catalyst mixture comprising (i) a carboxylate salt of an alkali metal or an alkaline earth metal or mixtures thereof, (ii) a tertiary amine, and (iii) a quaternary ammonium carboxylate salt, wherein the equivalent ratio of carboxylate metal salt: tertiary amine is a value less than about 3:1, and the quaternary ammonium carboxylate salt is present in an amount which enhances the char structure of polyisocyanurate foams made with the catalyst mixture and subjected to flammability char tests.

Abstract: A liquid stabilizer composition for polyether polyols used in the production of flexible and semiflexible polyurethane foams contains a mixture of 4-alpha,alphadinethylbenzyl diphenylamine and 4,4'-bis-(alpha,alphadimethylbenzyl) diphenylamine.

Abstract: Process for producing a flexible polyurethane foam through reaction of a polyol with a polyisocyanate in the presence of an amine catalyst, a blowing agent, and a foam stabilizer, the amine catalyst comprising at least one of the imidazoles represented by the general formula below: ##STR1## wherein R.sup.1 is alkyl of 1 to 4 carbons, dimethylaminopropyl, benzyl, vinyl, or hydroxyalkyl of 1 to 3 carbons; R.sup.2 is hydrogen, alkyl of 1 to 4 carbons, allyl, benzyl, or phenyl; and R.sup.3 and R.sup.4 are respectively hydrogen, alkyl of 1 to 4 carbons, or hydroxymethyl.

Abstract: Stable urea group-containing dispersions are obtained in situ by reacting carbon dioxide with an amine in the presence of a continuous phase carrier. These amine/carbon dioxide condensation adducts dispersed in the carrier are employed in the formation of polyurethane foams, polyurethane elastomers and coatings, and polyurethane microcellular foams.

Abstract: A method for preparing a polyurethane foam which comprises reacting an organic polyisocyanate and a polyol in the presence of a blowing agent, cell stabilizer and a catalyst composition which comprises a quaternary ammonium carboxylate inner salt having the following formula I ##STR1## where R.sub.1 -R.sub.3 are independently C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.8 cycloalkyl or a heterocycle, C.sub.6 -C.sub.10 aryl or heteroaromatic. R.sub.1 and R.sub.2 or R.sub.1 -R.sub.3 together with the nitrogen atom can also be part of nitrogen containing ring system such as piperidine, morpholine, triethylenediamine, imidazole, or 1,8-diazabicyclo-[5.4.0]undec-7-ene. R.sub.4 is a divalent R.sub.1.

Abstract: It has been found that in addition to acting as an auxiliary blowing agent, various salts of formic acid may be used to tailor the reactivity characteristics of rigid, polyurethane foam formulation. Salts of particular interest are: ammonium formate, sodium formate, and potassium formate. By varying amounts and combinations of the above salts, characteristics of a formulation's reactivity such as cream time, gel time, rise time, and tack-free time may be manipulated.

Abstract: The present invention provides a foamable epoxy resin composition (A) 100 parts by weight of a liquid epoxy resin (B) 0.5-20 parts by weight of a latent curing agent, (C) 0.5-15 parts by weight of a foaming agent having a decomposition temperature of 100.degree.-220.degree. C., (D) 0.05-5 parts by weight of a surface active agent and (E) 10-200 parts by weight of a rubbery elastomer or a powdery halogen-free thermoplastic resin of 150 .mu.m or less in average particle diameter, which composition has a melt viscosity of 2.5.times.10.sup.3 -5.times.10.sup.4 dPa.multidot.s at the decomposition temperature of said foaming agent. The composition can provide a foamed material of rigidity and good heat resistance, having an expansion ratio of 5 times or more and a dense cell structure of 0.5 mm or less in average cell diameter.

Abstract: The invention relates to a process for the manufacture of polyurethane foamed plastics which are formed by adding the polyurethane reactants to a solution of salts which decompose upon the exothermic polymerization reaction of said reactants to give off nitrogen gas which in turn foams the resultant polyurethane plastic.

Abstract: A liquid stabilizer composition for polyether polyols used in the production of flexible and semiflexible polyurethane foams contains a mixture of 4-alpha,alpha-dimethylbenzyl diphenylamine and 4,4'-bis-(alpha,alpha-dimethylbenzyl) diphenylamine.

Abstract: The invention relates to the use of an acridans of Structure (I) as a stabilizer, preferably combined with hindered amine, phenolic, and phosphite stabilizers for stabilizing polyether polyols for polyurethane flexible foams and as stabilizers for the polyglycols, heat transfer fluids, lubricating additives.

Abstract: A stabilizer composition useful as an additive for polyether polyols, particularly those employed in the manufacture of polyurethane foams, is provided which comprises a diarylamine, a sterically hindered phenol and a pentaerythritol diphosphite.

Abstract: Polyoxyalkylene polyols initiated with melamine and coinitiated with toluene diamine and oxyalkylated with one or more alkylene oxides have relatively low viscosity and are suitable for preparing polyurethane foams.

Abstract: The present invention relates to a process for producing a cellular or microcellular polyurethane foam wherein the reactants provide a built-in blowing capability. The process is effected by reacting a polyisocyanate with a carboxy-modified polyol to form a polyurethane and carbon dioxide, said carbon dioxide acting as an in situ blowing agent to foam said polyurethane into a cellular or microcellular polyurethane foam. In another aspect, the present invention relates to a process for forming an integral skin cellular or microcellular polyurethane foam by reacting, in a closed mold, a polyisocyanate with a carboxy-modified polyol to form a polyurethane and carbon dioxide.

Abstract: It has been found that the use of specific expanded organic microspheres greatly improve the RIM process by (i) significantly enhancing the blowing action of air and/or nitrogen, (ii) providing for uniform density of the molded part, (iii) allowing for the reduction of internal mold pressures, (iv) substantially eliminating surface defects, (v) allowing for a significant reduction in density in the molded product, (vi) allowing for a substantial increase in the amount of air and/or nitrogen that can be dissolved in the isocyanate-reactive component, and (vii) significantly reducing shrinkage in the molded part.

Abstract: The present invention relates to a process for producing a cellular or microcellular polyurethane foam wherein the reactants provide a built-in blowing capability. The process is effected by reacting a polyisocyanate with a carboxy-modified polyol to form a polyurethane and carbon dioxide, said carbon dioxide acting as an in situ blowing agent to foam said polyurethane into a cellular or microcellular polyurethane foam, said foam being formed in the absence of any chlorinated fluorocarbon blowing agents. In another aspect, the present invention relates to a process for forming an integral skin cellular or microcellular polyurethane foam by reacting, in a closed mold, a polyisocyanate with a carboxy-modified polyol to form a polyurethane and carbon dioxide.

Abstract: The present invention relates to a stabilized composition containing a polyol/melamine and an effective stabilizing amount of an amine terminated polyether.

Abstract: A method for preparing a polyurethane foam which comprises reacting an organic polyisocyanate and a polyol in the presence of a blowing agent, cell stabilizer and a catalyst composition which comprises a quaternary ammonium carboxylate inner salt having the following formula I ##STR1## where R.sub.1 -R.sub.3 are independently C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.8 cycloalkyl or a heterocycle, C.sub.6 -C.sub.10 aryl or heteroaromatic. R.sub.1 and R.sub.2 or R.sub.1 -R.sub.3 together with the nitrogen atom can also be part of nitrogen containing ring system such as piperdine, morpholine, triethylenediamine, imidazole, or 1,8-diazabicyclo-[5.4.0]-undec-7-ene. R.sub.4 is a divalent R.sub.1.

Abstract: A process for producing a urethane foam having a high density outer surface layer, of the type wherein a plastic liquid containing aromatic isocyanates, polyols, a catalyst, low-molecular polyols used as a crosslinker or a chain extender, a blowing agent consisting of water, and an assistant is poured into a closed mold through a one-shot molding process, a certain type of catalyst is added to create a difference in gas evolving reaction between an inner part and an outer part of the plastic liquid within the mold so as to form a high density layer on the outer surface of a urethane form. The catalyst includes a piperazine compound, a morpholine compound, or a mixture thereof. An imidazole compound, a triazine compound, an amidine compound or an organic acid salt of the amidine compound, or a mixture resulting from any combination thereof may be used in combination with the piperazine compound or a morpholine compound.

Abstract: Polyurethane foams of excellent properties are produced by reacting a) one or more polyether polyols, b) a polymethylene poly(phenyl isocyanate) having a methylene-bis(phenyl isocyanate) content of from 70 to 77% by weight, c) melamine, d) a phosphorous containing compound and d) water as the blowing agent. The isocyanate must have a specific 4,4' to 2,4'-isomer ratio and the amounts of melamine and phosphorous must be within narrowly defined limits.

Abstract: Polyether polyols and polyurethane foams are stabilized by including therein a stabilizer composition of (a) tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane and (b) a reaction product of diphenylamine and diisobutylene wherein the molar ratio of the amine to the diisobutylene is 1:1.1 to 1:2.5. The stabilizer composition may contain a third synergistic component, phenothiazine or certain alkyl derivatives of phenothiazine. The stabilizer composition may further contain trihydrocarbyl phosphite to stabilize the color of same.

Abstract: A process for producing a foamed polymer comprises the steps of: mixing, in a dissolver, a mixture constituted by at least one isocyanate and a first unsaturated anhydride, which is charged to the dissolver in the liquid state and at a relatively high temperature; progressively cooling said mixture, with continued stirring, until a temperature not higher than 22.degree. C. is reached; adding to the mixture, with the latter being still kept with continuous stirring, a second unsaturated anhydride, at least one foaming agent, a vinylidene compound, poly(vinyl chloride) and a heat stabilizer; maintaining the mixture with continuous stirring, at said temperature, until a paste is obtained which is poured, after being preliminarily filtered, into a mould or container; curing said paste by charging the container to an oven at atmospheric pressure, and at a temperature not higher than 80.degree. C.; completing the curing of the paste-like mixture under pressure, by increasing temperature up to 180.degree. C.

Abstract: A rigid polyurethane foam obtained by foaming a special polyol component and an isocyanate component in the presence of a blowing agent comprising water and at least one member selected from the group consisting of 1,1-dichloro-2,2,2-trifluoroethane and 2,2-dichloro-2-monofluoroethane possesses balanced excellent properties, has no surface void, and shows only slight expansion after molding. Therefore, it can be effectively used as a heat insulator, in particular, a heat insulator for refrigerators.

Abstract: A process for preparing a flame-resistant, elastic soft polyurethane foam includes admixing a portion of expanded graphite having a particle size of from 0.2 to 1 mm as a flame retardant and a portion of melamine, with a foam reaction mixture of polyol and polyisocyanate.

Abstract: Polyolefin resin compositions and oriented microporous films prepared from same comprising an ethylene-propylene block copolymer having an ethylene content of about 10 to about 50 wt %, a propylene homopolymer or random propylene copolymer having up to about 10 wt % of a comonomer of ethylene or an .alpha.-olefin of 4 to 8 carbon atoms, and components selected from a low molecular weight polypropylene, a beta-spherulite nucleating agent and an inorganic filler, and to processes for forming such films wherein the microporous films have improved breathability, strength, toughness and break elongation.

Abstract: Preparation of a polyurethane and/or polyisocyanurate product by the reaction of a composition containing an organic polyisocyanate, an active hydrogen containing compound and water as a blowing agent using an effective amount of a molecular sieve containing sorbed amine catalyst and/or crosslinker.

Abstract: The present invention relates to reactive systems comprising(a) a storable mixture of (i) a polyisocyanate component comprising at least one organic polyisocyanate, and (ii) an epoxide component stabilized by heating in the presence of an alkylating agent, wherein said heating is optionally carried out in the further presence of part of the polyisocyanate component (i),(b) an isocyanate-reactive component containing at least two isocyanate-reactive groups in a quantity such that 0.1 to 0.9 isocyanate-reactive groups are present for every isocyanate group in component (a), wherein at least 10% by weight of component (b) comprises compounds having a molecular weight greater than about 2000,(c) optionally, tertiary amines in a quantity such that the total storable mixture contains at least 0.005 mole of tertiary amine nitrogen atoms for each 100 g of the total amount of the storable mixture, and, optionally,(d) other auxiliaries and additives.

Abstract: A high water, high resiliency polyurethane foam composition comprising polyisocyanate, conventional polyol, polymer polyol, diethanolamine, silicone surfactant, water and catalyst, the improvement which comprises a cycloaliphatic diamine of the following formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are independently hydrogen or a C.sub.1 -C.sub.4 alkyl group, and a catalyst composition consisting essentially of 0.05 to 0.3 parts gel catalyst and 0.075 to 0.5 parts acid-blocked blowing catalyst, per 100 parts polyol.

Abstract: New particularly effective fire retardent elements based on foams and expandable graphite are characterized in that they additionally contain one or more components from the group consisting of phosphate-containing polyols, borates and amine salts.

Abstract: The present invention relates to a process for making a flame retardant polyurethane foam which comprises reacting a reaction mixture consisting essentially of a propylene oxide-based polyol that is essentially free of ethylene oxide moieties, a polyisocyanate, melamine in an amount of between about 5 and about 55 parts by weight per hundred parts of the polyol, a halogenated phosphate supplemental flame retardant in an amount of between 8 and about 50 parts by weight per hundred parts of the polyol, and water in an amount of between about 3 and about 6 parts by weight per hundred parts of the polyol, said polyol being further characterized by a molecular weight of between about 2,500 and about 6,000, to provide a polyurethane foam characterized by enhanced flame retardancy.

Abstract: A stain resistant polyvinyl chloride covered polyurethane foam article in which the polyurethane foam is made using a tertiary amine catalyst composition in which the amine functionality is 10-40 mole % neutralized with an acid composition consisting essentially of 10-100 mole % strong acid and 0-90 mole % weak acid.

Abstract: Blowing agents and blowing agent mixtures for preparing a cellular thermosetting plastic foam comprise either (1) a non-chlorinated, partially hydrogenated fluorocarbon with the general formula H.sub.x F.sub.y C.sub.z ; (2) a non-chlorinated, partially hydrogenated fluorocarbon ether with the general formula H.sub.x F.sub.y C.sub.z --O--C.sub.m F.sub.n H.sub.p ; (3) a non-chlorinated, non-hydrogenated, fully fluoronated fluorocarbon; (4) an azeotropic mixture having a boiling point below 50 degrees Celsius; or (5) any mixture of the foregoing. The azeotropic mixtures are produced from organic compounds having surface active properties that enable the blended azeotropic mixture to become miscible with polymer resins. Among the preferred compounds for use in azeotropic mixtures are n-pentane, acetone, methyl alcohol, methyl formate, ethyl formate, ethyl alcohol, 2-methyl butane, nitromethane, cyclopentane, 2,3,-dimethyl butane, 2,2,-dimethyl butane, and dimethyl sulfide.

Abstract: Polyether polyols and polyurethane foams are stabilized by including therein a liquid stabilizer composition of (a) 2,6-di-tert-butyl-4-sec-butylphenol, (b) a reaction product of diisobutylene, styrene and diphenylamine and (c) phenothiazine or C.sub.9-26 -alkyl substituted phenothiazone and wherein the ratio of the phenol to the reaction product is about 1:5 to 5:1 and the ratio of the mixture of components (a) and (b) to the phenothiazone compound is about 5.0:0.1 to 4.0:1.0. The stabilizer composition may further contain trihydrocarbyl phosphite to stabilize the color of same.

Abstract: A polyurea elastomer foam is disclosed. Specifically, the polyurea foam of this invention includes an (A) component including an isocyanate and a (B) component including (1) a primary amine terminated polyoxyalkylene polyol, (2) a chain extender, (3) water employed as the sole blowing agent and (4) a surfactant employed as a foam stabilizer. The polyurea foam of this invention is characterized as a rigid, closed cell foam.

Abstract: Polyether polyols and polyurethane foams are stabilized by including therein a liquid stabilizer composition of (a) 2,6-di-tert-butyl-4-sec-butylphenol, (b) a reaction product of diisobutylene, styrene and diphenylamine and (c) phenothiazine or C.sub.9-26 -alkyl substituted phenothiazine and wherein the ratio of the phenol to the reaction product is about 1:5 to 5:1 and the ratio of the mixture of components (a) and (b) to the phenothiazine compound is about 5.0:0.1 to 4.0:1.0. The stabilizer composition may further contain trihydrocarbyl phosphite to stabilize the color of same.

Abstract: The present invention relates to foam compositions which are expanded with hydrohalocarbon blowing agents in the presence of additives which decrease the formation of haloalkenes during the polymerization. Thus, the present invention provides compositions comprising polyisocyanate, polyol, hydrohalocarbon blowing agent, catalyst, surfactant, and at least one additive wherein the additive is capable of decreasing the amount of decomposition of said dehydrohalocarbon blowing agent to haloalkenes during polymerization of the polyisocyanate and the polyol.Depending upon the polyol and polyisocyanate used and the quantity of polyisocyanate used, the compositions may be used in pour-in-place molded foams; rigid urethane spray foams; rigid high and low density foams for slabstock, froth foams, and molded foams; rigid laminated boardstock; or specialty foams.

Abstract: A method for the preparation of polymeric foams which comprises reacting an organic polyisocyanate with a cyclic carbonate having at least one isocyanate-reactive substitutent attached to the carbonate ring.

Abstract: A method for preparing hard polyurethane and polyisocyanurate foams wherein an isocyanate and an active hydrogen containing compound are made to react in the presence of a catalyst, a foam stabilizer and a blowing agent which contains chloropropane, the used foam stabilizer being mainly of the non silicon type.

Abstract: The present invention is directed to a novel internal release agent for the production of polyurethane and/or polyurea elastomers, to an isocyanate reactive composition containing that release agent and to the use of the release agent in a RIM process. The release agent is the reaction product of i) a polyester derived from a polymerized fatty acid and either neopentyl glycol or 2,2,4-trimethyl-1,3-pentane diol and ii) an aliphatic monoisocyanate.

Abstract: A process for the manufacture of a rigid, closed-cell polyisocyanurate foam from a foam forming mixture comprising an organic polyisocyanate, a polyol, a blowing agent, and a catalyst, utilizing a polyester polyol as the sole polyol, and chlorodifluoromethane or a mixture of chlorodifluoromethane and at least one co-blowing agent as the blowing agent.

Abstract: A fire retardant composition comprising a dispersion of a solid fire retardant additive in a liquid isocyanate-reactive compound having a functionality of from 2 to 8 and an average equivalent weight of from about 31 to about 5000 and, as anti-settling agent, an effective amount of a fatty acid ester and/or amide. The composition is useful for preparing polyurethane foams.

Abstract: A process for preparing a dispersion of a filler e.g., melamine, urea or borax in a dispersion or graft polymer polyol is provided. The process comprises (1) dispersing the filler in a suitable basestock (e.g., a polyether polyol) and (2) thereafter using this as the basestock for preparing the dispersion or graft polymer polyol.The polymer which is prepared in dispersed form in the second step may be for example (1) the reaction product of a polyamine, hydrazine or hydrazide and an isocyanate (PHD polymer) or (2) the reaction product of an olamine and an isocyanate (PIPA polymer). Alternatively styrene and acrylonitrile can be graft polymerised in the basestock in step (2). The new dispersion or graft polymer polyols containing dispersed filler are useful in the manufacture of fire resistant polyurethane foam for e.g., furniture applications.

Abstract: A method of producing a polyurethane foam comprising the steps of dissolving rapidly and substantially completely a non-condensible non-reactive gas in a liquid isocyanate component or a liquid polyol component or both while the isocyanate and polyol components are maintained separate from one another, while controlling the flow of the non-reactive gas to maintain a predetermined dissolved gas to liquid ratio, and while maintaining the component in which the nucleating agent is being dissolved under pressure sufficient to maintain the gas in solution and to hold substantially constant the dissolved gas to liquid ratio and mixing the previously separated isocyanate and polyol components together while reducing the pressure to nucleate the dissolved gas in the isocyanate and polyol components and while impinging liquid streams of the composition together thereby enhancing mixing and permitting the mixture to foam so as to form a fine celled polyurethane foam.

Abstract: A method for the preparation of polymeric foams which comprises reacting an organic polyisocyanate with a cyclic carbonate having at least one isocyanate-reactive substituent attached to the carbonate ring.

Abstract: Melamine preparation comprising 80 to 99.9% by weight of melamine having an average particle size of 0.01 to 0.1 mm and 0.1 to 20% by weight of cyanuric acid or derivatives thereof and a stable dispersion prepared therefrom in polyether polyols, which is used for the production of flame-retardant polyurethane foams.

Abstract: This invention deals with novel copolymers having K values from 5 to 80 prepared by the radical polymerization of:(A) 20 to 80 weight percent, based on the total weight of (A) and (B), of at least one olefinic unsaturated polyoxyalkylene alcohol adduct or a polyester alcohol adduct;(B) 80 to 20 weight percent, based on the total weight of (A) and (B), of at least one vinyl monomer selected from the group consisting of N-vinylformamide, N-vinyl-2-pyrrolidone, N-vinyl-piperidone, N-vinyl-2-caprolactam, N-vinylimidazole, N-vinyl-2-ethylene-urea and N-vinyl-2-propylene-urea;(C) 0 to 40 parts by weight of glycidyl acrylate and/or glycidyl methacrylate;(D) 0 to 10 parts by weight of at least one .alpha.,.beta.-monoolefinic unsaturated acid; and(E) 0 to 30 parts by weight of at least one olefinic unsaturated carboxylic acid amide and or carboxylic acid ester and/or styrene;whereby the parts by weight of (C), (D) and (E) are each based on 100 parts by weight of monomers (A) and (B).

Abstract: Hydrocarbon oils having a high aromaticity (at least 85%, preferably 95-100%) and a boiling point of about 342.degree. to about 510.degree. C. (about 650.degree. to about 950.degree. F.) are used as partial or total replacements for the foam stabilizers used in the preparation of both rigid, closed cell polyurethane foams and flexible, open cell polyurethane foams. These oils are useful as a replacement for both silicon surfactants and organic (i.e., non-silicon) surfactants. For certain blowing agents (e.g., trichlorofluoromethane and methylene chloride), hydrocarbon oils having a boiling point range of about 399.degree. to 454.degree. C. (about 750.degree. to about 850.degree. F.) are preferred. Highly aromatic oils having a boiling point of about 281.degree. to about 510.degree. C. are useful for reducing the vapor pressure of toluene diisocyanate and for preventing the low temperature crystallization of toluene diisocyanate or diphenylmethane diisocyanate.

Abstract: The present invention relates to a process for the preparation of polyurethane foams comprising reacting polyisocyanates with compounds having a molecular weight of from 400 to 10,000 and containing at least two isocyanate-reactive hydrogen atoms, in the presence of water and/or organic blowing agents, catalysts, melamine having a particle size of from about 5 to about 90 micrometers as a flameproofing agent. The process is optionally carried out in the presence of other flameproofing agents, compounds containing at least two isocyanate-reactive hydrogen atoms and having a molecular weight of from 32 to 399, and known surface-active additives and auxiliaries.