Abstract: The invention relates to a process for the preparation of aliphatic-aromatic polyamide-imides in the absence of phenols.

Abstract: Reinforced cellular or noncellular molded polyurethane parts are prepared by heating a mixture of reinforcing materials and a heat-curable composition of polyisocyanates and polyols in an open or closed mold, said composition being storage-stable at room temperature and containing, optionally, auxiliaries and additives. In said composition, the polyisocyanate is dispersed in the form of discreet particles having particle diameters from 0.1 to 150 .mu.m in the polyol and the polyisocyanate particles are deactivated on their surfaces such that from 0.01 to 20 equivalent percent of the total available isocyanate groups are deactivated and such that the ratio of free isocyanate groups to hydroxyl groups is from 0.7:1 to 2.5:1.The polyurethane molded parts are suitable for use as self-supporting trim parts, reinforcement parts, or molded parts for various applications.

Abstract: The invention relates to a heat-hardened molded material produced from a resin mixture of a polyfunctional epoxide, a polyfunctional isocyanate and a reaction accelerator, which optionally contains additives and/or fillers. The objective is to make a resin mixture which permits the manufacture of a highly heat-resistant molded material, and which has at the same time a high-temperature cycle resistance and good mechanical properties. For this purpose, the polyfunctional epoxide of the resin includes a polyoxyalkylene glycol polyglycidyl ether.

Abstract: A method for preparing polyurethane product by the reaction of an organic polyisocyanate with a polyester or polyether polyol in the presence of a catalytically effective amount of a catalyst system consisting essentially of a tertiary amine and 1 to 35 wt %, based on the tertiary amine, of an N-hydroxyalkyl quaternary ammonium carbonylate salt. The use of such catalyst system advantageously improves the cure time of the urethane reaction, when compared to a system containing solely a tertiary amine, while maintaining the same initiation of the reaction. This advantage can be transferred to a delay in the initiation time while maintaining or shortening the cure time by adjustments in the total amount of the catalyst system used.

Abstract: A polyurethane containing an oligomer of a molecular weight of at most 5,000, which has at least either urethane or urea bonds, is terminated with inactive groups and does not have any group reactive with alcoholic hydroxyl and isocyanate groups of raw materials for urethane preparation in its molecule, at most in an amount not to cause deterioration of the desired characteristics of the polyurethane. The polyurethane of the present invention generates less static electricity than the polyurethane of the prior art and can be easily coated by electrostatic deposition.

Abstract: A two part RIM nylon-based urethane block polymer consists of an anionic metal salt catalyst in minor proportions and a prepolymer consisting of the reaction product of a diisocyanate with a mixture of a polymeric triamine having primary amine groups and a polyether diol in a large excess of a ring lactam which serves as a reaction diluent. The prepolymer preparation process is characterized by the immediate formation of a visible high molecular weight polymer gel which redissolves with continued agitation. No free or extractable polymers, diols or isocyanate is observed in the polymer product.

Abstract: An improved polyurethane lacquer for coating an elastomer containing at least one polyfunctional aromatic nitroso compound as an adhesion improver and optionally, lacquer-nonreactive spacer particles.

Abstract: This invention provides reaction resin molded materials (OX/ICR molded materials) containing oxazolidinone and isocyanurate rings prepared from reaction resin mixtures of polyepoxides and polyisocyanates (EP/IC resins) in the presence of a hardening catalyst and has as an object to provide a simple manufacturing method for heat resistant OX/ICR molded materials with improved mechanical properties. According to this invention, EP/IC resins which are capable of casting and impregnating and which are free from solvents are provided. These resins have a formula mole ratio of EP:IC of about 1 to 5 and a viscosity of up to 7,000 mPa sec at 25.degree. C. and are cross-linked by means of tertiary amine or imidazole hardening catalysts at gelling temperatures of up to 130.degree. C. and post-hardening temperatures of 130.degree. to 200.degree. C. to produce OX/ICR molded materials with a mole ratio OX:ICR greater than 1, wherein the reaction of the epoxy and isocyanate groups is above 90% after the hardening.

Abstract: A one component polyurethane precursor suitable as an in-mold coating composition composed of a prepolymer of an organic polyisocyanate with a polyol of a polyether polyol of 2 and 3 hydroxyl groups or a polyester polyol of 2 and 3 hydroxyl groups to give a free NCO content of about 3 to about 15% with a salt complex of a diamine, such as NaCl complex of MDA. The amount of filler and plasticizer, viz, those preferably of the crown or pseudocrown ethers preferably are adjusted to give the precursors a viscosity of about 5 to about 50 pascal seconds at the temperature the precursors are applied, but usually less than about 80.degree. C. These precursors are spread, applied or preferably injected onto the surface of the fiberglass molding viz a polyester or epoxy resin one and pressed at a pressure of about 5 to 200 psi (34,475 to 1,379,000 pascals) and higher at a temperature of at least 80.degree. C. to cure the precursor to give a polyurethane coating on the fiberglass molding.

Abstract: Novel carbamic and carbonic acid derivatives are provided by simultaneous reaction of a secondary amine and a tertiary amine with carbon dioxide. These derivatives correspond in general to the formula ##STR1## in which R.sub.1 and R.sub.2 may be individual substituents attached to the N or together form with N a heterocyclic moiety; R.sub.3, R.sub.4, R.sub.5 may be individual short chain alkyl or hydroxyalkyl substituents on the N or form therewith a monocyclic or bicyclic heterocyclic moiety. These described compounds find particular use as heat activatable delayed action catalysts especially for use in polyurethane formulations.

Abstract: Polyisocyanato-polyisocyanurates are prepared by catalytically cyclotrimerizing a polyisocyanate in the presence of a catalytically effective amount of an aminosilyl catalyst, and which is characterizing by terminating the cyclotrimerization reaction when a predetermined desired amount of isocyanurate groups has been obtained, by adding to the reaction mixture a reaction terminating amount of an organic catalyst deactivating compound comprising at least one free hydroxyl moiety, or the reaction product of such hydroxylated organic catalyst deactivating compound with an isocyanate.

Abstract: This invention relates to polymer dispersions prepared by the in situ polymerization of an ethylenically unsaturated monomer or mixture of monomers in a chain extender in the presence of a free radical polymerization initiator and a polyamide stabilizer.The invention also relates to mixtures of the polymer dispersions with compounds having two or more active hydrogen atoms as determined by the Zerewittinoff method. These mixtures are used to prepare polyurethane products.

Abstract: An adhesive for flocking elastomers, more especially apolar elastomers, such as EPDM. The adhesive contains an isocyanate-terminated polyurethane prepolymer and, as an adhesion promoter, a reaction product of an aromatic diisocyanate with a polyfunctional epoxide, particularly triglycidyl isocyanurate. The strength of adhesion and resistance of the bonds can be further increased by the addition of aromatic nitroso compounds, for example, 1,4-dinitrosobenzene.

Abstract: There are provided a wide range of polyurethane products, e.g., cellular, dense elastomer, and integral skin microcellular products, obtained by the reaction of (a) a polyisocyanate compound, (b) a polyol, (c) optionally a chain extender and/or blowing agent with/without other known additives, (d) in the presence of a non-hydroxyl flow modifier characterized by carbon and hydrogen atoms, at least one and, generally, a plurality of oxyalkylene groups, and at least one urethane, ##STR1## group. Several of the polyurethane products exhibit unique properties, e.g., foamed articles with capability to conduct static electricity, soft elastomers characterized by improved coefficient of friction, etc. Several classes of the flow modifiers are novel per se. The polyurethane products can be synthesized via the one shot or prepolymer process. Multipackage systems, in particular, two and three component systems are useful in molding operations, e.g., manufacture of shoe soles.

Abstract: New and improved storage stable, one package, heat-curable polyurea/urethane coating compositions are disclosed which comprise:(a) a mixture or prepolymer of(i) a poly aliphatic isocyanate compound of the formula: ##STR1## wherein R and R' are each, independently, hydrogen, alkyl or substituted alkyl and X is a bridging means selected from divalent aliphatic, cycloaliphatic, or aromatic groups, or a polymeric adduct of said aliphatic isocyanate compound possessing poly aliphatic isocyanate functionality; and(ii) an approximately stoichiometric amount of at least one monomeric or polymeric compound containing a plurality of isocyanate reactive hydrogens; and(b) a minor effective amount of a polymerization catalyst.The compositions cure when heated to above about 100.degree. C. to form coatings which exhibit good abrasion resistance, solvent resistance, weather resistance and good adhesion to a wide variety of substrates.

Abstract: Storable polypropylene ether polyurethane compositions composed of (a) a prepolymer of a polypropylene ether glycol and sufficient organic polyisocyanate to give preferably an excess of about 3 to 15 percent NCO in said prepolymer with the proviso that the free NCO is obtained from methylenedi-p-phenyl diisocyanate and (b) a complex of an alkali metal salt with 4,4'-methylenedianiline (MDA), said composition being relatively inactive at temperatures below 100.degree. C., but being heat activatible at much higher temperatures to effect a cure. The improved composition wherein a catalyst is present in said composition which effectively lowers the cure temperature, said catalyst being a pseudocrown ether containing radicals having the formula --y--CH.sub.2 --CH.sub.2).sub.n with y being nitrogen, sulfur or oxygen and n has values sufficient to form the crown structure, viz., at least 3 or more.

Abstract: Adhesive, coating, or sealant compositions containing prepolymer(s) derived from MDI (or derivative(s) thereof) and polyol(s) containing primary hydroxyl groups, together with bis[2-N,N-dialkylamino)alkyl]ether(s).

Abstract: A process of coloring polyurethane resins during the production of same with reactive colorants having the formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 are selected from halogen, carboxylic acid, alkanoyl, aryloyl, alkyl, aryl, cyano, sulfonylalkyl, sulfonylaryl, thioalkyl, thioaryl, sulfinylalkyl, sulfinylaryl, dithioalkyl, dithioaryl, thiocyano, amidoalkyl, amidodialkyl, oxyalkyl, oxyaryl, hydrogen, sulfonamidoalkyl, sulfonamidoaryl, sulfonamidodialkyl, sulfonamidodiaryl, carbocyclic forming polymethylene chains, sulfenamidoalkyl, sulfenamidodialkyl, sulfenamidoaryl, sulfenamidodiaryl, sulfinamidoalkyl, sulfinamidodialkyl, sulfinamidoaryl, sulfinamidodiaryl; and A is an organic dyestuff coupler that is resistant to stannous octanoate and flame retardant compounds and which has functionality through reactive substituents thereof.

Abstract: High molecular weight aromatic polyamines are produced by hydrolyzing a polyisocyanate having an isocyanate content of from 21 to 52.5% and an isocyanate-reactive group-containing compound having a molecular weight of from 400 to 10,000 in the presence of an excess of water. The reactants are used in quantities such that the equivalent ratio of isocyanate to isocyanate-reactive groups is from 0.1 to 5. Further, water is used in an amount such that the equivalent ratio of water to isocyanate groups is greater than 1. Low molecular weight compounds containing isocyanate-reactive groups, solvents, basic catalysts and urethanization catalysts may also be included in the mixture to be hydrolyzed. The hydrolysis is carried out at a temperature of from -20.degree. to 175.degree. C. The product amine is isolated from the reaction mixture by procedures such as phase separation, extraction and distillation. The polyamines thus-produced are particularly useful in the production of polyurethanes.

Abstract: A catalyst and process are provided for producing polyurethanes by contacting an organic polyol and an organic isocyanate with a catalyst comprising an N-substituted alkoxyalkyl piperazine and preferably additionally comprising an N-alkoxyalkyl morpholine wherein the alkylene moieties of the morpholine and piperazine are independently selected from the group consisting of C.sub.1 to about C.sub.5 alkylene moieties, and wherein the alkoxy moieties are independently selected from the group consisting of C.sub.1 to about C.sub.3 alkoxy moieties.

Abstract: A polyamide-imide resin which can give a varnish having a high resin content, excellent in storage stability and heat resistant final products such as insulated wire can be produced by reacting an aromatic diisocyanate with a tricarboxylic acid anhydride in the presence of a basic solvent while adjusting the resin content at 40% by weight or more, and adding a compound having one active hydrogen atom before, during or after the above-mentioned reaction so as to adjust the reduced viscosity of the resin to 0.27 or lower.

Abstract: The present invention relates to a method of avoiding a too rapid curing reaction in production processes where a prepolymer is cured, giving an extension of the so-called pot life. By adding a small amount of a compound, whose structural formula comprises the metal-binding part ##STR1## to form complexes with transition metals catalyzing the curing reaction, an extension of the pot life is achieved without any negative influence on the qualities of the produced product. Preferably a tetracycline compound is added.

Abstract: Process for the production of polyurethane prepolymers based on monocyclic and dicyclic diisocyanates, in which a prepolymer based on a dicyclic diisocyanate is produced in a prepolymer based on a monocyclic diisocyanate of comparatively lower reactivity. The products obtained by this process contain terminal isocyanate groups and are distinguished by a reduced content of free monomeric diisocyanates.

Abstract: The invention relates to reaction injection molded elastomers derived from high molecular weight active hydrogen containing materials, a chain extender, a polyisocyanate and an acid amide as an internal mold release agent imparting superior hot tear strength. The reaction injection molded (RIM) elastomers of this invention are useful, for example, as automobile body parts.

Abstract: Amino and amido carboxylates of divalent tin, zinc, cobalt and nickel which are useful as catalysts for polyurethane formulations. Such compounds correspond to either of the formulae: ##STR1## wherein R.sub.1 and R.sub.2 are independently C.sub.1 -C.sub.20 alkyl, C.sub.6 -C.sub.20 cyclohydrocarbyl, C.sub.2 -C.sub.20 hydroxyalkyl or alkoxyalkyl, or R.sub.1 and R.sub.2 together with N form a nitrogen-containing heterocyclic ring of 5 or 6 atoms;R.sub.3 is a --CH.sub.2).sub.n group where n is an integer from 2 to 6 or a ##STR2## group where R.sub.4 is an alkyl, cycloalkyl or aryl group of up to 6 carbon atoms;A is ##STR3## wherein R.sub.5 and R.sub.6 are independently hydrogen, C.sub.1 -C.sub.4 alkyl or R.sub.5 and R.sub.6 together form part of a six-member cyclohydrocarbyl ring, andM is divalent tin, zinc, cobalt or nickel.

Abstract: The condensation of organic polyisocyanates, lactams, and cyclic polycarboxylic acid anhydrides in the presence of mono- or disubstituted imidazole catalyst results in a polyamide imide having an increased softening temperature.

Abstract: There are provided low temperature, storage stable, liquid mixture of (1) isocyanato-containing prepolymers obtained from the reaction of linear and/or slightly branched polyols and a polyisocyanate characterized by a methylene group --CH.sub.2 -- bonded to two benzenoid nuclei, and (2) a non-hydroxyl-containing flow modifier which is compatible with the said prepolymer. Novel liquid mixtures thus prepared exhibit little tendency to crystallize or phase separate when stored for prolonged periods of time, i.e., well below room temperature for several days.

Abstract: Novel polyamide-imide resin compositions, useful for electrically insulating conductors, are prepared by polycondensing a tribasic acid anhydride compound and a diisocyanate in an inert organic solvent in the presence of a catalytic amount of an oxyanion or amine compound at a high solids content, and controlling the reaction to prevent a great increase in viscosity.

Abstract: A novel anaerobically curable resin composition of one-part type is provided. The composition consists essentially of the following components (a), (b) and (c) in the specified amounts; the component (a) being a mixture of polymerizable components consisting of (i) an addition-reaction product of a polybutadiene-based liquid rubber, a polyisocyanate and a hydroxyl group-containing methacrylate, and (ii) a polymerizable methacrylate; the component (b) being a salt of o-benzoic sulfimide with a specified amine; and the component (c) being an ammonium or amine salt of an aminopolycarboxylic acid. The process for preparation of the composition comprises the step of adding the specified amounts of the aminopolycarboxylic acid or an alkali metal salt thereof and an ammonia water or a volatile organic amine to the component (a), the step of stirring and heating the mixture to remove volatile matters partly until the pH is decreased to 9 or lower, and the step of adding thereto the component (b).

Abstract: A polyamide-imide resin which can give a varnish having a high resin content, excellent in storage stability and heat resistant final products can be produced by reacting an aromatic diisocyanate with a tricarboxylic acid anhydride in the presence of a basic solvent while adjusting the resin content at 40% by weight or more, and adding a specific amount of lactam and a specific amount of an alcohol and/or an oxime separately before, during or after the above-mentioned reaction so as to adjust the reduced viscosity of the resin to 0.10 to 0.27.

Abstract: Disclosed is a polyurethane composition of multi-pack type, curable at ambient temperature, which comprises an isocyanate component having oxadiazinetrione ring, an active hydrogen component and a Lewis base whose basic site has no hydrogen active to NCO group and a process for producing polyurethane from the composition.The composition has excellent curability at ambient temperature and is useful for coatings, adhesives and elastomers as high solid content type or solventless type. The cured product polyurethane has good mechanical properties.

Abstract: Coating or adhesive composition having extended pot life and short cure time comprising an organic polyol, an organic polyisocyanate, an organo-zinc cure rate catalyst, and a compound selected from (a) beta-dicarbonyl compounds, (b) alpha-hydroxy ketones, (c) fused aromatic beta-hydroxy ketones, and (d) beta-hydroxy nitrogen-heterocyclic fused aromatics.Also disclosed are methods of preparing such coating or adhesive compositions, cured coatings and adhesives, and articles containing said coating or adhesive.

Abstract: A novel, heat curable, liquid polymer composition is disclosed which comprises a modified polyurethane oligomer containing terminal ethylenic unsaturation and a free radical generating catalyst. The composition has utility in preparing molded articles and coatings.

Abstract: Novel high molecular weight resins, useful for electrically insulating conductors, are prepared by polycondensation of a dianhydride, or a mixture of two or more dianhydrides, and a diisocyanate in an inert organic solvent, preferably in the presence of a catalytic amount of 2-methylimidazole.

Abstract: The process described herein comprises the preparation of polyimides by the reaction of aromatic dianhydrides and aromatic diisocyanates in the presence of a metal acetylacetonate, such as Al, Co, Fe, Ni, Zr, etc. By using appropriate proportions, the polyimides may be end-capped with either anhydride or isocyanate groups. The use of the acetylacetonate permits the use of lower temperatures for imide ring closure thereby avoiding undesirable coreaction between anhydride groups and certain solvents. "Polyimide dianhydride" is an anhydride-terminated polyimide; and "polyimide diisocyanate" is an isocyanate-terminated polyimide as represented by the respective formulas: ##STR1## wherein Ar', Ar and n are as defined hereinafter. By this process, the polyimide dianhydride product has an anhydride activity of at least 0.17 as defined herein regardless of the type of solvent used.

Abstract: Monomeric or polymeric isocyanurates, e.g., polyisocyanate/polyisocyanurates, are prepared by catalytically cyclotrimerizing an isocyanate, e.g., an aliphatic or cycloaliphatic isocyanate, in the presence of an aminosilyl catalysis initiator, e.g., a mono- or diaminosilane, a silylurea or a silazane, having the structural formula:R.sub.(4-n) Si--NR'R"].sub.n (I)wherein R is a saturated or unsaturated, aliphatic, cycloaliphatic, aryl, aralkyl or alkylaryl monovalent hydrocarbon radical, or halo or cyano substituted such radical, and further wherein any two radicals R may together form a single divalent such hydrocarbon radical; R' is R, SiR.sub.3 or an amido radical having the structural formula: ##STR1## wherein R'" is R or SiR.sub.3, with R being as above defined, and further wherein R', when R' is neither the amido radical nor SiR.sub.

Abstract: Disclosed is a process for the preparation of polyamide compounds by reacting at least one polycarboxylic acid with at least one diisocyanate in the presence of a catalyst comprising at least one mono-alkali metal salt of dicarboxylic acid. The polyamide compounds prepared by this process have a substantially linear configuration and a high degree of polymerization and, therefore, are suitable for the manufacture of fibers, films and molded articles.

Abstract: A solvent-free resin mixture which is curable by thermosetting, in particular for use as a highly heat-resistant impregnating, varnishing and casting resin for the insulation of electrical conductors and windings in electrical machinery and equipment, contains at least one reactive liquid epoxide compound, at least one reactive liquid polyisocyanate and at least one latent hardener for these components; the mixture also contains triallyl cyanurate as a crosslinking agent.

Abstract: A prepolymer having a molecular weight of at least 3,000 is made from a polyether polyol where all the OH groups are capped with an aliphatic polyisocyanate. When mixed with water the prepolymer reacts to form an elastomeric cross-linked polyurethane gel adhesive which can be used to adhere fibers to from a nonwoven fabric. Examples of the aliphatic diisocyanate are IPDI (isophorone diisocyanate) and hydrogenated MDI. A catalyst can also be applied to the aqueous mixture to accelerate the adhesive binder formation.

Abstract: This invention is directed to a polyurethane product produced by a one step process, in the absence of a polymerization catalyst, with reactants, and additives, if any, being initially intermingled in the ambient room temperature range and reacted with intermingling in the absence of externally added heat. The reactants are (1) aliphatic, aromatic, or cycloaliphatic having at least two isocyanate groups and (2) diol/polyol compounds having at least two sterically unhindered hydroxyl groups. The product is a liquid, homogeneous adhesive material characterized by a natural absence of polymerization catalyst residue and capable of being cured because of the presence of unreacted isocyanate groups, the isocyanate reactant being charged in excess of the stoichiometric requirement of the diol/polyol reactant.

Abstract: Novel high molecular weight resins, useful for electrically insulating conductors, are prepared by polycondensing a mixture of anhydrides, and a diisocyanate and/or a diamine in an inert organic solvent, preferably in the presence of a catalytic amount of 2-methylimidazole.

Abstract: A heat-resistant heterocyclic polymer consisting of units of the general formula ##STR1## wherein R, R.sup.1 and X are as defined hereinbelow anda method for producing heat-resistant heterocyclic polymers, consisting in that, at a temperature of 90.degree. to 400.degree. C., there is conducted a reaction of polyfunctional nitrile-containing compounds with polyfunctional isocyanates.The proposed polymers are stable at temperatures from 300.degree. to 350.degree. C. Materials based thereon are capable of retaining their properties at a temperature of up to 400.degree. C. for long periods of time. The method is simple and can be effected without isolation, purification or drying the polymer, which allows combining the process of producing the polymer with that of producing a finished article.

Abstract: A coating or molding composition including a polyisocyanate and an unsaturated imide, and having a ratio of total isocyanate functions to total polymerizable double bonds in the imide in the range of from 0.3 to 15, is addition polymerized to hard, imide group containing polymers characterized by the recurring unit: ##STR1## Coatings and shaped articles formed from such polymers are hard, tough, thermally stable, solvent resistant and are good insulators.

Abstract: Polyimide-amide-carboxylic acids produced by reacting an aromatic diamine with an aromatic tetracarboxylic acid dianhydride in amounts of 1.5 to 2.0 moles of the latter per mole of the former in the presence of an inert solvent, and reacting the resulting intermediate reaction product with an aromatic diisocyanate in about equivalent amounts at a temperature of 50.degree. to 100.degree. C. while removing generated carbon dioxide from the reaction system are good in heat resistance, wear resistance, chemical resistance, etc.

Abstract: This invention relates to the use of an isocyanate blocked imidazole or imidazoline compound as a catalyst for effecting cure of powdered epoxy resins. The isocyanate blocked imidazole or imidazoline imparts an extended pot life to a curable epoxy powder coating composition while effecting cure at substantially lower temperatures than normally would be required and with faster cure times.

Abstract: The reaction of an isocyanate such as toluene diisocyanate with itself to form an isocyanurate or with an active hydrogen compound such as diethylene glycol to form a urethane is catalyzed by the presence of an ar-ammonium areneoxide such as 4-dodecyl-2-trimethylammonium phenoxide.

Abstract: Rigid, solid, non-cellular, urethane polymer compositions can be prepared which are the reaction product of at least one polyhydric alcohol with at least one organic polyisocyanate in the presence of a low molecular weight urethane modifier adduct which is the reaction product prepared, for instance, by reacting (1) at least one polyisocyanate and at least one monohydric alcohol or (2) at least one monofunctional isocyanate with at least one monohydric or polyhydric alcohol. Said adduct can also consist of mixtures of (1) and (2). Such polymers when prepared in the presence of any catalyst for urethane formation which is a liquid or solid at ambient temperature, set quickly to solid, rigid polymers having a density of at least one gram per cubic centimeter. They can be demolded after combining the materials, without the addition of heat from an external source, within a period of less than one minute to about 15 minutes.

Abstract: Polyamideimides prepared by polycondensation of trimellitic anhydride, diphenyl methane diisocyanate and an isocyanate mixture are provided. These preparations exhibit low viscosity in high-solids solutions and are useful as wire enamels and topcoats over polyester and polyesterimide base coats.

Abstract: This invention relates to isocyanate prepolymers activated with alkyl ureas and to a two-stage process for the production of polyurethane elastomers based on 1,5-naphthylene diisocyanate, using alkyl ureas as activators.

Abstract: The present invention relates to a process for the production of polyureas by reacting organic polyisocyanates containing blocked isocyanate groups with organic compounds containing at least two primary and/or secondary amino groups in the presence of catalysts which accelerate the condensation reaction of the above-mentioned starting materials, characterized in that compounds containing at least one guanidine group corresponding to the following formula: ##STR1## are used as catalysts.