MXPA96001785A - Aspartate-functional polyhydantoin prepolymers and their use in coating compositions - Google Patents

Abstract

The present invention relates to aspartate-functional hydantoin prepolymers prepared by reacting a polyisocyanate having a functionality of at least 1.8 with a polyaspartate corresponding to the formula wherein X represents an organic group which has a valency of n and is inert towards isocyanate groups at a temperature of 100 DEG C or less, and R1 and R2 may be the same or different and represent optionally substituted hydrocarbon radicals, R3 and R4 may be identical or different andrepresent hydrogen or organic groups which are inert towards isocyanate groups at a temperature of 100 DEG C or less and n has a value of 2 to 6, preferably 2 to 4 and more preferably 2. The present invention is also directed to compositions suitable for the production of coatings, adhesives, elastomers, potting compounds or composite matrices containing these polyhydantoin prepolymers in combination with optionally blocked polyisocyanates.

Description

POLYHYDANTOIN PREPOLIMERS WITH ASPARTATE FUNCTIONALITY AND ITS USE IN COATING COMPOSITIONS BACKGROUND TO THE INVENTION ÁÉL. FIELD OF THE INVENTION The present invention relates to polyamide prepolymers with aspartate functionality and their use in combination with optionally blocked polyisocyanates for the production of polyureas, especially as binders in coating compositions. DESCRIPTION OF THE PRIOR ART Coating compositions containing, as binders, optionally blocked polyisocyanates in combination with polyether, polyester or polycarbonate polyols are known. In addition to the preparation of coatings, these compositions can also be used for the production of elastomers, encapsulated compounds, mixed matrices and in other related applications. One of the shortcomings of using these known polyols is that they do not possess sufficient thermal, chemical and hydrolytic stability. Accordingly, an object of the present invention is to provide improved co-reactants for optionally blocked polyisocyanates. This object can be achieved with the hydantoin prepolymers with aspartate functionality according to the present invention. The reaction of polyaspartates with poly JK soci. Nates to form coatings is described in US Pat. No. 5,126,170. The polyisocyanates are mixed with polyaspartiates and then reacted after the The mixture has been applied to a suitable substrate to form a coating containing urea groups. The coating is cured at low temperatures so that the conversion of the urea groups into hydantoin groups does not occur. In German Patent Publication No. 2,158,945, they are made Reacting polyisocyanates with β-aminocarboxylic acid derivatives (broadly encompassing the aspartates, see Example 7) to form open-chain urea derivatives, which can subsequently be heated to 6-membered 2,4-dioxohexahydropyrimidine derivatives . U.S. Patent 3,639,418 relates to the reaction of bis-aspartates with monoisocyanates to form an intermediate which is then converted to the corresponding hydantoin by heating at elevated temperatures. U.S. Patent 3,549,599 refers to polyhydantoins substituted with carboxylic acid esters, prepared by reacting stoichiometric amounts of polyaspartates with polyisocyanates and subsequently converting the urea groups to hydantoin groups. Unless chain terminating monoaspartates are used During their production, the resulting products are high molecular weight polymers, which can be crosslinked through the ester group that remains after the formation of hydantoin by transesterification or aminolysis reactions. In addition, this reference refers mainly to the use of aromatic polyisocyanates to prepare the polyhydantoins. It can be seen that such polyhydantoins are inferior to the corresponding polyhydantoins prepared from (cyclo) aliphatic polyisocyanates with respect to the viscosity and color of the polyhydantoins and the flexibility, color and weather resistance of the resulting products. None of the foregoing references suggests the preparation of the poly-hydantoin prepolymers with aspartate functionality according to the present invention or their use as co-reactants for optionally blocked polyisocyanates. COMPENDIUM OF THE INVENTION The present invention relates to hydantoin prepolymers with aspartate functionality, prepared by Reacting a polyisocyanate with a functionality of at least 1.8 with a polyaspartate corresponding to the formula wherein X represents an organic group having a valence of n and is inert towards isocyanate groups at a temperature of 100 ° C or less, and R1 and R2 may be the same or different and represent optionally substituted hydrocarbon radicals, R and R4 may be identical or different and represent hydrogen or organic groups that are inert towards isocyanate groups at a temperature of 100 ° C or less and n has a value from 2 to 6, preferably from 2 to 4 and more preferably 2. The present invention also relates to compositions suitable for the production of coatings, adhesives, elastomers, encapsulated compounds or mixed matrices containing polyhydantoin prepolymers in combination with optionally blocked polyisocyanates. . DETAILED DESCRIPTION OF THE INVENTION The polydanitide prepolymers with aspartate functionality according to the invention are prepared by reacting a polyisocyanate with a polyaspartate. The polyisocyanates have a functionality of from 1.8 to 6, preferably from 2 to 6, more preferably from 2 to 4 and most preferably 2. Suitable polyisocyanate starting materials include monomeric diisocyanates and polyisocyanate adducts, preferably monomeric diisocyanates. . Suitable monomeric diisocyanates can be represented by the formula R (NCO) 2 in which R represents an organic group obtained by separating the isocyanate groups from an organic diisocyanate with a molecular weight of from about 112 to 1,000, preferably from about 140 to 400. Preferred diisocyanates for the process according to the invention are those represented by the above formula in which R represents a divalent aliphatic hydrocarbon group with 4 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group with 5 to 15 carbon atoms, a group divalent araliphatic hydrocarbon with 7 to 15 carbon atoms or a divalent aromatic hydrocarbon group with 6 to 15 carbon atoms. Examples of suitable organic diisocyanates include 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 1,1-dodecamethylene diisocyanate, , 3- and 1,4-cyclohexane diisocyanate, l-isocyanato-2-isocyanatomethyl cyclopentane, l-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane (isophorone diisocyanate or DIIF), bis- (4) - isocyanatocycline) -methane, 2,4-diisocyanate-dicyclohexyl-methane, 1,3- and 1,4-bis- (isocyanatomethyl) -cciohexane, bis- (4-isocyanato-3-methyl-cyclohexyl) - methane, diisocyanate of,, *, a'-tetramethyl-1, 3- and / or -1,4-xylylene, 1-isocyanato-1-methyl-4 (3) -isocyanatomethyl cyclohexane, 2,4- and diisocyanate or 2, 6-hexahydrotoluylene, 1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 2,6-toluylene diisocyanate, 2,4- and / or 4,4-diisocyanate • -diphenyl-methane, 1, 5-naphthalene diisocyanate and mixtures thereof. Polyisocyanates containing 3 or more isocyanate groups such as 4-isocyanatomethyl-1, 8-octamethylene diisocyanate and aromatic polyisocyanates such as 4,4", 4" -triphenylmethane diisocyanate and polyphenylene polymethylene polyisocyanates obtained by phosgenation can also be used. of condensation products of indigo / formaldehyde. Preferred organic diisocyanates include 1,6-hexamethylene diisocyanate, l-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (isophorone diisocyanate or DIIF), bis- (4-isocyanatocyclohexyl) -methane, diisocyanate a , a, -1, "-tetramethyl-l, 3- and / or -1,4-xylylene, 1-isocyanato-l- ^ methyl-4 (3) -isocyanatomethyl cyclohexane, 2,4- and / or diisocyanate 2, 6-hexahydrotoluylene, 2,4- and / or 2,6-toluylene diisocyanate and 2,4- and / or 4,4'-diphenyl methane diisocyanate In accordance with the present invention, the polyisocyanate component it can also be in the form of a polyisocyanate adduct. Suitable polyisocyanate adducts are those containing isocyanurate, uretdione, biuret, urethane, allophanate, carbodiimide and / or oxadiazinetrione groups. The polyisocyanate adducts have an average functionality of 2 to 6 and an NCO content of 5 to 30% by weight. 1) Polyisocyanates containing isocyanurate groups which can be prepared as described in DE- * PS 2,616,416, EP-OS 3,765, EP-OS 10,589, EP-OS 47,452, US-PS 4,288,586 and US Pat. PS 4,324,879. Generally, the isocyanato isocyanurates have an average NCO functionality of 3 to 3.5 and an NCO content of 5 to 30%, preferably 10. to 25% and most preferably 15 to 25% by weight. 2) uretdione diisocyanates which can be prepared by oligomerization of a portion of the isocyanate groups of a diisocyanate in the presence of a suitable catalyst, for example, a trialkyl phosphine catalyst, and may be used in admixture with other aliphatic and / or cycloaliphatic polyisocyanates, particularly polyisocyanates containing isocyanurate groups summarized in (1) above. i 3) Polyisocyanates containing biuret groups which can be prepared according to the methods described in U.S. Pat. 3,124,605; 3,358,010; 3. 644,490; 3,862,973; 3,906,126; 3,903,127; 4,051,165; 4. 147,714; or 4.22Q.749, using co-reactants such as water, tertiary alcohols, primary and secondary monoamines and primary and / or secondary diamines. These polyisocyanates preferably have an NCO content of 18 to 22% by weight and an average NCO functionality of 3 to 3.5. 4) Polyisocyanates containing urethane groups, which can be prepared according to the process described in US Pat. No. 3,183,112 by reacting excess amounts of polyisocyanates, preferably * diisocyanates, with glycols and low molecular weight polyols with molecular weights of less than 400, such as trimethylol propane, glycerin, 1,2-dihydroxy propane and mixtures thereof. The polyisocyanates containing urethane groups have an NCO content, most preferably from 10 to 20% by weight and a NCO functionality (average) from 2.5 to 3. 5) Polyisocyanates containing allophanate groups, which can be prepared according to the procedures described in U.S. Pat. 3,769,318, 4,160,080 and 4,177,342. The polyisocyanates containing allophanate groups have an NCO content, most preferably * do, from 12 to 21% by weight and an NCO functionality (average) from 2 to 4.5. 6) Polyisocyanates containing isocyanurate and allophanate groups, which can be prepared in accordance with procedures described in U.S. Patents 5,124,427, 5,208,334 and 5,235,018, the disclosures of which are incorporated herein by reference, preferably polyisocyanates containing these groups in a monoisocyanurate group to monoalphanate groups ratio of about : 1 to 1:10, preferably from about 5: 1 to 1: 7. 7) Polyisocyanates containing carbodiimide groups, which can be prepared by oligomerization of di- or polyisocyanates in the presence of known carbodiimidation catalysts, are described in DE-PS 1,092,007, US-PS 3,152,162 and DE-OS 2,504,400, 2,537,685 and 2,552,350. 8) Polyisoxates containing oxadiazinetrione groups and containing the reaction product of two moles of a diisocyanate and one mole of carbon dioxide. Preferred polyisocyanate adducts are polyisocyanates containing isocyanurate groups, biuret groups and mixtures of isocyanurate groups with any of allophanate or uretdione groups. Suitable polyaspartates which can be used as starting materials for the production of the aspartate-functional polyhydantoin prepolymers according to the invention include those corresponding to the formula: wherein X represents an organic group having a valence of n and is inert towards isocyanate groups at a temperature of 100 ° C or less, preferably a hydrocarbon group obtained by separating the amino groups from an aliphatic, araliphatic or cycloaliphatic polyamine, more preferably a diamine, and Ri R2 may be the same or different and represent optionally substituted hydrocarbon radicals, preferably an alkyl group containing from 1 to 9 carbons and more preferably methyl, ethyl or butyl groups, R3 and R4 may be identical or different and represent hydrogen or organic groups which are inert towards isocyanate groups at a temperature of 100 ° C or less, preferably hydrogen, and n has a value of at least 2, preferably from 2 to 6, more preferably from 2 to 4 and most preferably 2. These polyaspartates can be prepared by reacting esters of maleic or fumaric acid optionally substituted with polyamines. Suitable optionally substituted maleic or fumaric acid esters are those corresponding to the formula R 1 OOC-CR 3 = CR 4 -COOR 2 (II) wherein R 1 R2, R 3 and R are defined as above. Examples of optionally substituted maleic or fumaric acid esters suitable for use in the preparation of the polyaspartates include the dimethyl, diethyl and dibutyl esters (eg, di-n-butyl) of maleic acid and fumaric acid and the corresponding acid esters maleic or fumaric substituted with methyl in position 2 and / or 3. The polyamines suitable for preparing the poliasparta¬ coughs include those corresponding to the formula X- (NH2) n where X and n are defined as before. Polyamines include high molecular weight amines, with molecular weights of 800 to about 10,000, preferably 800 to about 6,000 and low molecular weight amines, with molecular weights less than 800, preferably less than 600. Molecular weights are average molecular weights in number (Mn) and are determined by terminal group analysis (NH number). Examples of These polyamines are those in which the amino groups are attached to aliphatic, cycloaliphatic, araliphatic and / or aromatic carbon atoms. Suitable low molecular weight polyamines include ethylene diamine, 1,2- and 1,3-propane diamine, 2-methyl-l, 2-25 propane diamine, 2,2-dimethyl-l, 3-propane diamine, 1, 3- and 1,4-butane diamine, 1,3- and 1,5-pentane diamine, 2-methyl-1, 5-pentane diamine, 1,6-hexane diamine, 2,5-dimethyl-2, 5- hexane diamine, 2,2,4-. and / or 2, 4, 4-trimethyl-l, 6-hexane diamine, 1,7-heptane diamine, 1,8-octane diamine, 1,9-nonane diamine, inonane tria, 1,10-decane diamine, 1, 11-undecane diamine, 1, 12-dodecane diamine, l-amino-3-aminomethyl-3, 5, 5-trimethylcylohexane, 2,4-y / p 2, 6-hexahydrotoluylene diamine, 2,4 '- and / or 4,4'-diaminodicyclohexyl-methane, 3,3'-dialkyl-4,4'-diamino-dicyclohexyl methanes (such as 3,3'-dimethyl- 4,4 '-diamino- 35 dicyclohexyl methane and 3,3' -diethyl-4,4 * -dia ino-dicyclohexyl methane), 1,3- and / or 1,4-cyclohexane diamine, 1,3-bis ( methylamine) -cydohexane, 1,8-p-menthane diamine, hydrazine, hydrazides of icarbazido carboxylic acids, bis-hydrazides, bis-semicarbazides, phenylene diamine, 2,4- and 2,6-toluylene diamine, 2, 3-and 3,4-toluylene diamine, 2,4'- and / or 4,4"-diamino diphenylmethane, polyphenylene polymethylene polyamines of high functionality, obtained by the condensation reaction of aniline / formaldehyde, N, N, N- tris- (2-aminoethyl) -amine, guanidine, melamine, N- (2-aminoethyl) -1, 3-propane diamine, 3,3'-diamino-benzidine, polyoxypropylene amines, polyoxyethylene amines, 2, 4-bis- (4'-aminobenzyl) -aniline and mixtures thereof. Also suitable are the amine terminated polyethers having the required molecular weight, such as the Jeffamine resins, for example, Jeffamine D-230 and T-403, available from Huntsman. W5 Suitable high molecular weight polyamines include those prepared from the known polyhydric polyurethane compounds, especially polyethers.

The polyamines can be prepared by reacting the hydroxylic compounds with an excess of the above-described polyisocyanates to form NCO prepolymers and subsequently hydrolyzing the terminal isocyanate group to an amino group. Preferably, the polyamines are prepared by converting the terminal hydroxy groups of the polyhydroxy compounds to amino groups, for example, by amination.

The preferred high molecular weight polyamines are amine terminated polyethers such as the Jeffamine resins available from Huntsman. Preferred polyamines are l-amino-3-aminomethyl-3,5,5-trimethyl-cyclohexane (isophorone diamine or IPDA), bis-30 ((4-aminocyclohexyl) methane, bis- (4-amino-3-methylcyclohexyl) - methane, 1,6-diaminohexane, 2-methyl pentamethylene diamine, ethylene diamine, -triaminononane, 2,4- and / or 2,6-toluylene diamine, 4,4'- and / or 2, 4 • - diamino-diphenyl methane and the Jeffamine D-230 and T-403 resins The preparation of the polyaspartates from the aforementioned starting materials can be carried out, for example, at a temperature from 0 to 100 ° C using starting materials in proportions such that at least 1, preferably 1, olefinic double bond is present for each primary amino group.

# Batch in excess can be separated by distillation after the reaction. The reaction can be carried out in the absence of solvent or in the presence of suitable solvents such as methanol, ethanol, propanol, dioxane and mixtures of such solvents. The polysaccharide prepolymers with aspartate functionality according to the invention are prepared by reacting the polyisocyanates with the polyaspartates at a ratio of equivalents of aspartate groups (ie, secondary amino groups) to isocyanate groups of 1.05: 1 to 10: 1, preferably from 1.1: 1 to 10: 1 and more preferably «From 1.2: 1 to 10: 1. Preferably, the reaction is carried out by incrementally adding the polyisocyanate to the polyaspartate. The reaction to form the intermediate containing urea groups is carried out at a temperature of 10 to 100 ° C, preferable¬ to 80 ° C and more preferably 20 to 50 ° C. Upon completion of this addition reaction, the temperature is raised to 60 to 240 ° C, preferably to 80 to 160 ° C and more preferably to 100 to 140 ° C, to convert the urea groups to hydantoin groups with the elimination of a monoalcohol. Instead of forming the urea groups and hydantoin groups in two stages, the reaction can be carried out * I entirely at elevated temperatures in order to form the urea groups and hydantoin groups in one step. When polyisocyanates and polyaspartates are used with functionalities of 2, the poly-hydantoin prepolymers with aspartate functionality can be represented by the formula Wherein X, R1 R2, R3 and R are defined as above, R5 represents the residue obtained by separating the isocyanate groups from an organic diisocyanate, preferably an organic monomeric diisocyanate and p has a value from 1 to 20, preferably from 1 to 10. and more preferably from 1 to 5. The polyhydantoin prepolymers with functionality Aspartate can be used in combination with the monomeric diisocyanates or preferably the polyisocyanate adducts previously described to form two-component coating compositions. They can also be reacted with NCO prepolymers, which are prepared from of the monomeric polyisocyanates or polyisocyanate adducts described above, preferably monomeric diisocyanates, and organic compounds containing at least two isocyanate-reactive groups, preferably at least two hydroxy groups. These organic compounds include compounds of High molecular weight with molecular weights of 400 to about 6,000, preferably 800 to about 3,000, and optionally low molecular weight compounds with molecular weights below 400. Molecular weights are average molecular weights in number (Mn) and are determined by analysis of the terminal groups (OH index).

Examples of the high molecular weight compounds are polyester polyols, polyether polyols, polyhydroxy polycarbonates, polyhydroxy polyacetals, polyhydroxy polyacrylates, polyhydroxy polyester amides and polyhydroxy polythioethers. Polyester polyols, polyether polyols and polyhydroxy polycarbonates are preferred. Further details concerning the low molecular weight compounds and starting materials and methods for preparing the high molecular weight polyhydroxy compounds are described in U.S. Patent 4,701,480, which are incorporated herein by reference. Generally, the NCO prepolymers have an isocyanate content of about 0.5 to 30% by weight, preferably about 1 to 20% by weight, and are prepared in a known manner by the reaction of the aforementioned starting materials to a NCO / OH equivalent ratio of about 1.05: 1 to 10: 1, preferably about 1.1: 1 to 3: 1. The polysaccharide prepolymers with aspartate functionality can also be used in combination with blocked polyisocyanates to form one component compositions, which are cured at elevated temperatures. In these applications it is not necessary to convert the urea groups to hydantoin groups before combining these resins with the blocked polyisocyanates. This is because these compositions must be cured at elevated temperatures and while the resins are heated to the curing temperature, the urea groups can be converted to hydantoin groups. Suitable blocked polyisocyanates are prepared by blocking the monomeric diisocyanates, polyisocyanate adducts or NCO prepolymers previously described with a monofunctional blocking agent for isocyanate groups. Suitable blocking agents are known and include monophenols; primary, secondary or tertiary alcohols; easily forming compounds, enols such as acetoacetic ester, acetylacetone and malonic acid derivatives; secondary aromatic amines; imides; lactams; oximes; mercaptans; and triazoles. Polyhydantoin prepolymers with ^ Sk functionality. Aspartate is mixed with the preceding? M co-reactants in amounts sufficient to provide a ratio of equivalents of secondary amino groups to isocyanate groups of from 3: 1 to 1: 3, preferably from 2: 1 to 1: 2 and more preferably from 1.1: 1.0 to 1.0: 1.1. The resulting products prepared from the hydantoin prepolymers of According to the invention, they have improved hydrolytic, chemical and thermal stability when compared to known esters, carbonates and ethers, which are commonly used as co-reactants for polyisocyanates. The compositions containing the U-polyhydantoin prepolymers according to the invention are suitable for various applications such as binder components for the production of coatings, adhesives, foams, elastomers, encapsulated compounds, mixed matrices and microcellular elastomers. The compositions can also contain other known additives such as catalysts, pigments, fillers, leveling agents, anti-setting agents, UV stabilizers and the like. In a preferred embodiment, the compositions are used for the production of coatings by one or more layers to substrates by known methods such as spraying, brush coating, dipping or flooding or by means of doctor rollers or applicators. These coating compositions are suitable for the formation of coatings on various substrates, for example metals, plastics, wood, cement, concrete or glass. The coating compositions are particularly suitable for the formation of coatings on steel on steel plates, for example, for the manufacture of the bodies of the automobiles, panels of garniture of machines, barrels or containers. The substrates to be coated by the process according to the invention can be treated with suitable primers before carrying out the process according to the invention. After the substrates have been coated, the two-component compositions can be cured either at room temperature, for example, by air drying, or by so-called forced drying, or at elevated temperature. The one component compositions must be cured at elevated temperatures. It is very beneficial that the coatings do not degrade thermally even at the highest temperatures that can occur in the event of a failure of the coating plant. The invention is further illustrated but is not intended to be limited by the following examples, in which all parts and percentages are by weight, unless specifically indicated to the contrary. EXAMPLES The following starting materials were used in the examples: Bis-aspartate 1 210 parts of 4,4'-diamino-dicyclohexylmethane (1.0 mole) were added dropwise with stirring to 344 parts of diethyl acid ester maleic (2.0 moles) that were previously charged at room temperature in a 1 L three-necked flask equipped with a stirrer, thermometer and an addition funnel. The amine was added at a rate such that the exotherm did not increase the temperature of the reaction mixture above 50 ° C. After the addition was complete, the contents of the reaction flask were maintained at 50 ° C for a period of 12 hours. The resulting product was a clear, colorless liquid with a viscosity of about 1400 mPa.s (25 ° C) and a weight of amine equivalents of about 276. Bis-aspartate 2 were added dropwise, with stirring, to the mixture. parts of 2-methyl-l, 5-pentanediamine (1.0 mol) to 344 parts of maleic acid diethyl ester (2.0 mol) which were pre-charged at room temperature in a 1 L three-necked flask equipped with an agitator, thermometer and a funnel * addition. The amine was added at a rate such that the exotherm did not increase the temperature of the reaction mixture above 50 ° C. After the addition was complete, the contents of the reaction flask were maintained at 50 ° C for a period of 12 hours. The resulting product was a clear, colorless liquid with a viscosity of about 90 mPa.s (25 ° C) and a weight of amine equivalents of about 230. Bis-aspartate 3 I were added dropwise, with stirring, 170 parts of isophorone diamine (1, 0 mol) to 344 parts of maleic acid diethyl ester (2.0 moles) which were pre-charged at room temperature in a 1 L three-necked flask equipped with a stirrer, thermometer and addition funnel. The amine was added at a rate such that the exotherm did not increase the temperature of the reaction mixture above 50 ° C. After the addition was complete, the contents of the reaction flask were maintained at 50 ° C for a period of 12 hours. The resulting product was a clear, colorless liquid with a viscosity of about 500 mPa.s (25 ° C) and a weight of amine equivalents of about 230. Bis-aspartate 4 * were added dropwise, with stirring, 116 parts of 2-methyl-l, 5-pentanediamine (1.0 mole) to 456 parts of maleic dibutyl ester (2.0 moles) that were charged 0 previously at room temperature in a three-neck, 1 L flask equipped with an agitator, thermometer and an addition funnel. The amine was added at a rate such that the exotherm did not increase the temperature of the reaction mixture above 50 ° C. After the addition was complete, the contents of the reaction flask were maintained at 50 ° C for a period of 12 hours. The resulting product was a clear, colorless liquid with a viscosity of about 64 mPa.s (25 ° C) and a weight of amine equivalents of about 286. Examples 1-6 - Preparation of poly-hydantoin prepolymers with aspartate functionality The bis -spartate was charged into a flask in a nitrogen atmosphere and then 1,6-hexamethylene diisocyanate (DIH) was added dropwise to the bis-aspartate, keeping the temperature below 80 ° C. Then, the reaction mixture was heated under vacuum at 120 ° C until the generation of alcohol ceased, which indicated the end of the hydantoin formation. The following table expresses the amounts of the reactants and the properties of the resultant aspartate-functional polyhydantoin prepolymers. 1 - . 1 - . 1 - Viscosity of the solution, determined in butyl acetate. All viscosities were measured using a Brookfield DV-II + viscometer equipped with a CP-52 spindle at 25 ° C.

EXAMPLES 7-9 - Preparation of polyhydrogentoin prepolymers with aspartate functionality The bis-aspartate was charged to a flask under a nitrogen atmosphere and then 1,6-hexamethylene diisocyanate (DIH) was added dropwise to the bis-aspartate, maintaining the temperature below 80 ° C. Then, the reaction mixture was heated under vacuum at 120 ° C until the generation of alcohol ceased, which indicated the end of the hydantoin formation i. The following table expresses the amounts of the reactants and the properties of the resultant aspartate-functional polyhydantoin prepolymers. 1 - Viscosity of the solution, determined in butyl acetate. All viscosities were measured using a Brookfield DV-II + viscometer equipped with a CP-52 spindle at 25 ° C. Although the invention has been described in detail in the foregoing for the purpose of illustration, it will be understood that such details only serve that purpose and that those skilled in the art can make variations without departing from the spirit and scope of the invention, except as which may be limited by the claims.

Claims (2)

CLAIMS 1. A hydantoin prepolymer with aspartate functionality, prepared by reacting a polyisocyanate with a functionality of at least 1.8 with a polyaspartate corresponding to the formula wherein X represents an organic group having a valence of n and is inert towards isocyanate groups at a temperature of 100 ° C or less, and Ri and R2 may be the same or different and represent optionally substituted hydrocarbon radicals, R3 and R4 may be identical or different and represent hydrogen or organic groups that are inert towards isocyanate groups at a temperature of 100 ° C or less and n has a value of 2 to 6. The hydantoin prepolymer of claim 1, wherein R2 and R2 represent a methyl, ethyl or butyl group and R3 and R4 represent hydrogen. 3. The hydantoin prepolymer of the claim

1, wherein n is 2. 4. The hydantoin prepolymer of the claim 2, where n is 2. 5. A hydantoin prepolymer with aspartate functionality corresponding to the formula in one X represents an organic group that has a valence of n and is inert towards isocyanate groups at a temperature of 100 ° C or less, and R? and R 2 may be identical or different and represent organic groups that are inert towards isocyanate groups at a temperature of 100 ° C or less, R 3 and R 4 may be identical or different and represent hydrogen or organic groups that are inert towards isocyanate groups at a temperature of 100 ° C or less and R5 represents the residue obtained by separating the isocyanate groups from an organic diisocyanate, p has a value from 1 to 20. The hydantoin prepolymer of claim 5, wherein R2 and R2 represent a methyl, ethyl or butyl group and R3 and R represent hydrogen. 7. The hydantoin prepolymer of claim 5, wherein r i is 2. 8. The hydantoin prepolymer of claim 6, wherein n is 2. The present invention relates to hydantoin prepolymers with aspartate functionality, prepared by reacting a polyisocyanate with a functionality of at least 1.8 with a polyaspartate corresponding to the formula wherein X represents an organic group having a valence of n and is inert towards isocyanate groups at a temperature of 100 ° C or less, and R? and R 2 may be the same or different and represent optionally substituted hydrocarbon radicals, R and R may be identical or different and represent hydrogen or organic groups that are inert towards isocyanate groups at a temperature of 100 ° C or less and n has a value of 2 to 6, preferably 2 to 4 and more preferably

2. The present invention also relates to compositions suitable for the production of coatings, adhesives, elastomers, encapsulated compounds or mixed matrices containing polyhydantoin prepolymers in combination with optionally blocked polyisocyanates.