MXPA97010184A - Compositions of depoliurea waterproof of two components - Google Patents

Compositions of depoliurea waterproof of two components

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Publication number
MXPA97010184A
MXPA97010184A MXPA/A/1997/010184A MX9710184A MXPA97010184A MX PA97010184 A MXPA97010184 A MX PA97010184A MX 9710184 A MX9710184 A MX 9710184A MX PA97010184 A MXPA97010184 A MX PA97010184A
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Mexico
Prior art keywords
groups
composition
group obtained
amino groups
polyisocyanate
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MXPA/A/1997/010184A
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Spanish (es)
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MX9710184A (en
Inventor
Sanjay Luthra
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Bayer Corporation
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Publication date
Priority claimed from US08/766,136 external-priority patent/US5736604A/en
Application filed by Bayer Corporation filed Critical Bayer Corporation
Publication of MX9710184A publication Critical patent/MX9710184A/en
Publication of MXPA97010184A publication Critical patent/MXPA97010184A/en

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Abstract

The present invention relates to an aqueous coating composition having a solids content of 20 to 96% by weight and containing a) a polyisocyanate component dispersible in water and having an average NCO functionality of 2 to 6 and b) a polyaspartate corresponding to formula (I): and c) water, which is present in an amount of at least 4% by weight based on the solids content of components a) and b), where components a) and b) are present in a sufficient quantity to provide an equivalent ratio of isocyanate groups to amino groups of at least 0.9

Description

COMPOSITIONS OF TWO COMPONENT POLYUREA COATING AQUEOUS BACKGROUND OF THE INVENTION Field of the Invention The present invention is directed to aqueous coating compositions containing, as a binder, hydrophilic polyisocyanates and polyaspartic acid esters. BACKGROUND OF THE INVENTION Two component coating compositions, carried in solvents, which contain, as a binder, a polyisocyanate component in combination with an isocyanate-reactive component, in particular a polyhydroxy component, are known. They are suitable for the formation of high quality coatings and can be adjusted to produce coatings that are hard, elastic, resistant to abrasion, resistant to solvents and especially resistant to atmospheric conditions. Two-component coating compositions are also known, which can be diluted with an organic solvent and contain, as a binder, a polyisocyanate component in combination with polyaspartic acid esters or mixtures of polyaspartic acid esters with or without polyhydroxy components and are described in US Patents 5,126,170 and 5,236,741. These compositions can be used to formulate coating compositions having a much lower viscosity at equivalent solvent contents than coating compositions in which the isocyanate-reactive component is based exclusively on polyhydroxy compounds. It is known that coating compositions based on polyaspartic esters provide excellent resistance to atmospheric conditions and a performance similar to two-component polyurethane coating compositions carried in solvents. The use of such coating compositions allows for reduced emissions of volatile organic compounds, which are increasingly being restricted by various government regulations. However, coating compositions based on polyisocyanates and polyaspartic esters can provide only a limited reduction in volatile organic content (VOC). Greater reductions in volatile organic content can not be achieved without increasing the viscosity of the compositions to the extent that film properties, shelf life and / or application characteristics are adversely affected. Water-borne two-component coating compositions are also known which contain, as a binder, a polyisocyanate or a polyisocyanate component dispersible in water in combination with an isocyanate-reactive component, for example polyhydroxy components carried in water or dispersible in water, and are described, for example, in U.S. Pat. 5,075,370 and 5,389,718. The use of such compositions allows the formulation of coating compositions having zero or no organic solvent and providing a substantially equivalent performance to conventional two-component polyurethane coating compositions, carried in solvents. It is an object of the present invention to provide coating compositions that 1) can be diluted with water, so that they do not require the large quantities of solvents required by the polyurethane coating compositions carried in known two-component solvents to obtain viscosities of satisfactory application, 2) can be formulated at higher solids contents than the known two-component aqueous polyurethane coating compositions and 3) can be used to prepare coatings having the desirable properties of known two-component coating compositions. These objects can be achieved with the aqueous, two-component polyurea coating compositions according to the present invention, which are based on hydrophilic polyisocyanates and polyaspartic acid esters, optionally in admixture with other isocyanate-reactive components. Even though it is not known that these polyaspartic acid esters are dispersible in water, they can be diluted with water and still produce smooth and continuous films. This would not be the case if the polyaspartic acid esters were not compatible with water. By using water as a non-organic solvent, improved application characteristics can be achieved without increasing the volatile organic content of the coating compositions according to the invention. An advantage of these coating compositions is that their curing development is not affected by low temperatures (40 ° F). The coating compositions can provide a variety of application and physical properties depending on the type of polyaspartic ester and the polyisocyanate component used and the stoichiometric ratios of isocyanate groups to aspartate (secondary amino) groups. Surprisingly, better chemical resistance can be obtained for coatings prepared from the coating compositions according to the invention using higher ratios than conventional isocyanate groups to amino groups. SUMMARY OF THE INVENTION The present invention is directed to an aqueous coating composition having a solids content of 20 to 96% by weight and containing a) a polyisocyanate component that is dispersible in water and has an average NCO functionality of 2 to 6 and b) a polyaspartate corresponding to the formula X- -N where X represents an organic group having a valence of n and is inert towards the isocyanate groups at a temperature of 100 ° C or less; R? And R2 may be the same or different and represent organic groups that are inert toward the isocyanate groups at a temperature of 100 ° C or less, or Rx and R2, together with the β-carbon atom, form a cycloaliphatic or heterocyclic ring; R3 and R4 may be identical or different and represent hydrogen or organic groups that are inert towards the isocyanate groups at a temperature of 100 ° C or less, and n has a value of 2 to 6 and c) water, which is present in an amount of at least 4% by weight based on the solids content of components a) and b), where components a) and b) are present in an amount sufficient to provide an equivalent ratio of isocyanate groups to amino groups of at least 0, 9: 1. DETAILED DESCRIPTION OF THE INVENTION The polyisocyanate compositions according to the present invention have a minimum average functionality of 2, preferably 2.5, and a maximum average functionality of 6, preferably 4.5. Suitable polyisocyanate adducts for use in the preparation of component a) of the present invention include those containing isocyanurate, uretdione, biuret, urethane, allophanate, carbodiimide or oxadiazinetrione groups.
The processes for the preparation of polyisocyanate adducts containing these groups are known and described in US Pat. 4,518,522, 4,663,377 and . 200,489, whose descriptions are incorporated by reference. Preferred polyisocyanate adducts according to the present invention are those containing isocyanurate groups, mixtures of isocyanurate groups and allophanate groups (for example, those described in US Pat. . 124,427, 5,208,334 and 5,235,018, the descriptions of which are hereby incorporated by way of reference) and mixtures of isocyanurate groups and uretdione groups. Suitable monomeric diisocyanates can be represented by the formula R (NC0) 2, wherein R represents an organic group obtained by removing isocyanate groups from an organic diisocyanate having 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 wherein R represents a divalent aliphatic hydrocarbon group having from 4 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group having from 5 to 15 carbon atoms. carbon, a divalent araliphatic hydrocarbon group having from 7 to 15 carbon atoms or a divalent aromatic hydrocarbon group having from 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, cyclohexane-1, 3- and -1,4-diisocyanate, l-isocyanato-2-isocyanatomethylcyclopentane, l-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (isophorone diisocyanate or DIIF), bis (4-isocyanatocyclohexyl) ) methane, 2,4'-dicyclohexylmethane diisocyanate, 1,3- and 1,4-bis (isocyanatomethyl) cyclohexane, bis (4-isocyanato-3-methylcyclohexyl) methane, diisocyanate of a, a, a ', a' -tetramethyl-1, 3- and / or -1, 4-xylylene, l-isocyanato-l-methyl-4 (3) -isocyanatomethylcyclohexane, 2,4- and / or 2,6-hexahydrotoluylene diisocyanate, diisocyanate of 1 , 3- and / or 1, 4-phenylene, 2,4- and / or 2,6-toluylene diisocyanate, 2,4- and / or 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate and its mixtures Polyisocyanates containing 3 or more isocyanate groups, such as 4-isocyanatomethyl-1, 8-octamethylene diisocyanate, and aromatic polyisocyanates, such as 4,4 ', 4"-triphenylmethanediisocyanate, and polyisocyanates can also be used. polyphenylpolymethylene obtained by phosgenation of aniline / formaldehyde condensates. Preferred organic diisocyanates include diisocyanate 1, 6-hexamethylene, l-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (isophorone diisocyanate or DIIF), bis (4-isocyanatocyclohexyl) methane, a, a, a ', a'-tetramethyl diisocyanate l, 3- and / or -1, 4-xylylene, l-isocyanato-l-methyl-4 (3) -isocyanatomethylcyclohexane, 2,4- and / or 2,6-hexahydrotoluylene diisocyanate, 2,4-diisocyanate and or 2, 6-toluylene and 2,4- and / or 4,4'-diphenylmethane diisocyanate. The 1,6-hexamethylene diisocyanate is especially preferred. The monomeric polyisocyanates or polyisocyanate adducts used to prepare the aqueous dispersions of the present invention are converted to hydrophilic by reaction with isocyanate-reactive compounds containing cationic, anionic and / or nonionic groups, preferably nonionic groups. Reaction components that ensure the dispersibility of the polyisocyanates include compounds that contain lateral or terminal hydrophilic ethylene oxide units and compounds that contain potential ionic groups or ionic groups. Compounds containing lateral or terminal hydrophilic ethylene oxide units contain at least one, preferably one, isocyanate-reactive group and are used in an amount sufficient to obtain a content of hydrophilic units of ethylene oxide of up to about 40% by weight. weight, preferably about 5 to 40% by weight and, more preferably, about 10 to 35% by weight based on the weight of the polyisocyanate. Compounds containing ionic groups or potential ionic groups contain at least one, preferably two, isocyanate-reactive groups and are used in an amount of up to about 120 milliequivalents, preferably about 5 to 80 milliequivalents, more preferably about 10 to 60 milliequivalents and, more preferably, about 15 to 50 milliequivalents per 100 grams of polyisocyanate. Hydrophilic components having terminal or side hydrophilic chains containing ethylene oxide units include compounds corresponding to the formulas H-Z-X-Y-R "or R R ' ) -C-CH2-N-CH2-CH-CCOO-NNHH-RR-INH-CO-ZXYR "where R represents a difunctional radical obtained by eliminating the isocyanate groups of a diisocyanate corresponding to those previously mentioned; hydrogen or a monovalent hydrocarbon radical containing from 1 to 8 carbon atoms, preferably hydrogen or a methyl group; R "represents a monovalent hydrocarbon radical having from 1 to 12 carbon atoms, preferably an unsubstituted alkyl radical which has from 1 to 4 carbon atoms; X represents the radical obtained by elimination of the terminal oxygen atom of a polyalkylene oxide chain having from 5 to 90 chain members, preferably 20 to 70 chain members, wherein at least about 40%, preferably at least about 65% of the chain members consist of ethylene oxide units and the remainder consists of other alkylene oxide units, such as propylene oxide, butylene oxide or styrene oxide units, preferably oxide units of propylene; Y represents oxygen or -NR '' '-, where R' "has the same definition as R", and Z represents a radical corresponding to Y, but can additionally represent -NH- The compounds corresponding to the above formulas can be produced by the methods according to US Patents 3,905,929, 3,920,598 and 4,190,566 (the descriptions of which are hereby incorporated by reference.) Monofunctional hydrophilic synthesis components are produced, for example, by alkoxylating a compound monofunctional such as n-butanol or N-methylbutylamine, using ethylene oxide and, optionally, another alkylene oxide, preferably propylene oxide The resulting product can be possibly modified (although this is less preferred) by reaction with ammonia to form the corresponding primary polyether amino The preferred monohydroxy functional polyethers are those in which the ethylene oxide portion has a minimum molecular weight of 200, preferably 250, and more preferably 300. The upper limit for the molecular weight of the ethylene oxide portion is 1000, preferably 950, more preferably 900, and more preferably 800. The minimum molecular weight for all of the polyether is 200, preferably 250 and, more preferably, 300. The upper limit for the molecular weight of the polyether is 1500, preferably 1200, more preferably 1000 and, more preferably, it is the same as the maximum molecular weight of the ethylene oxide portion. In other words, the most preferred polyethers are based exclusively on ethylene oxide. The compounds containing ionic groups or potential ionic groups to give hydrophilicity to the polyisocyanates can be cationic or anionic. Examples of anionic groups include carboxylate groups and sulfonate groups. Examples of cationic groups include tertiary and quaternary ammonium groups and tertiary sulfonium groups. The ionic groups are formed by neutralization of the corresponding potential ionic groups before, during or after their reaction with the polyisocyanate. When the potential ionic groups are neutralized before forming the modified polyisocyanate, the ionic groups are directly incorporated. When the neutralization is carried out after the formation of the prepolymer, potential ionic groups are incorporated. Suitable compounds for incorporating the carboxylate, sulfonate, tertiary sulfonium, and tertiary or quaternary ammonium groups discussed previously are described in US Pat. 3,479,310, 4,108,814, 3,419,533 and 3,412,054, the descriptions of which are hereby incorporated by reference. Suitable starter molecules for the production of the monofunctional polyethers include monoalcohols containing from 1 to 12 carbon atoms, preferably 1 to 4 carbon atoms, such as methanol, ethanol, propanol or butanol, cyclohexanol, 3-methyl-3-hydroxymethyloxetane and phenol. In the patent 4,472,550 additional cyclic starter molecules are exposed, the description of which patent is hereby incorporated by reference. The production of the emulsifiers takes place by reaction of the aliphatic polyisocyanates with compounds containing hydrophilic groups as described in the prior art references. In order to reduce the viscosity of the hydrophilic polyisocyanates, small amounts, ie, about 1 to 10% by weight, based on the solvent-free polyisocyanate composition, of an organic solvent such as ethyl acetate can be added. , acetone or methyl ethyl ketone to the compositions before use according to the invention. However, it is preferred not to use any organic solvent in the polyisocyanate composition of the present invention. Suitable polyaspartates for use according to the present invention include those corresponding to the formula: where X represents an organic group having a valence of n and is inert towards the isocyanate groups at a temperature of 100 ° C or less, preferably the group obtained, more preferably the hydrocarbon group obtained, by elimination of the amino groups of a polyamide. aliphatic, araliphatic or cycloaliphatic, more preferably a diamine, and R? And R2 may be the same or different and represent organic groups which are inert towards the isocyanate groups at a temperature of 100 ° C or less, preferably an alkyl group containing from 1 to 9 carbon atoms and, more preferably, methyl, ethyl groups or butyl, or Rx and R2, together with the β-carbon atom, form a cycloaliphatic or heterocyclic ring; R3 and R4 may be identical or different and represent hydrogen or organic groups that are inert towards the isocyanate groups at a temperature of 100 ° C or less, and n has a value of at least 2, preferably 2 to 6, more preferably 2 to 4 and, more preferably, 2. These polyaspartates can be prepared by reaction of optionally substituted esters of maleic or fumaric acid with polyamines. Suitable optionally substituted esters of maleic or fumaric acid are those corresponding to the formula R 1 OOC-CR 3 = CR 4 -COOR 2 (II), wherein R 1 R2, R 3 and R 4 are as defined above. Examples of optionally substituted esters of maleic or fumaric acid suitable for use in the preparation of the polyaspartates include dimethyl, diethyl and dibutyl (eg, di-n-butyl) esters of maleic acid and fumaric acid and the corresponding esters of the maleic or fumaric acid substituted by methyl in the 2 and / or 3 position. Suitable polyamines for preparing the polyaspartates include those corresponding to the formula X - (- NH 2) n, where X and n are as previously defined. Polyamines include high molecular weight amines having molecular weights of 400 to about 10,000, preferably 400 to about 6,000, and low molecular weight amines having molecular weights below 400. Molecular weights are number average molecular weights (Mn) and they are determined by analysis of final groups (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 polyamines of low molecular weight include ethylenediamine, 1,2- and 1,3-propanediamine, 2-methyl-1,2-propanediamine, 2,2-dimethyl-1,3-propanediamine, 1,3- and 1 , 4-butanediamine, 1,3- and 1,5-pentanediamine, 2- • methyl-1,5-pentanediamine, 1,6-hexanediamine, 2,5-dimethyl-2,5-hexanediamine, 2,2,4 and / or 2, 4, 4-trimethyl-1,6-hexanediamine, 1,7-heptane diamine, 1,8-octanediamine, 1,9-nonanediamine, triaminononane, 1,10-decanediamine, 1, 11-undecanediamine, 1,12-dodecanediamine, l-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 2,4- and / or 2,6-hexahydrotoluylenediamine, 2,4'- and / or 4 , 4'-diaminodicyclohexylmethane, 3,3 '-dialkyl-4,4'-diaminodicyclohexylmethanes (such as 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane and 3,3'-diethyl-4,4'-diamino- dicyclohexylmethane), 1,3- and / or 1,4-cyclohexanediamine, 1,3-bis (methylamino) cyclohexane, 1,8-p-methanediamine, hydrazine, semicarbazidocarboxylic acid hydrazides, bishidrazides, bissemicarbazides, Phenylenediamine, 2,4- and 2,6-toluylenediamine, 2,3- and 3,4-toluylenediamine, 2,4'- and / or 4,4'-diaminodiphenylmethane, higher functional polyphenylenepolymethylenepolyamines obtained by the aniline condensation reaction / formaldehyde, N, N, -tris (2-aminoethyl) amine, guanidine, melamine, N- (2-aminoethyl) -1,3-propanediamine, 3, 3'-diaminobenzidine, polyoxypropyleneamines, polyoxyethyleneamines, 2 , 4-bis (4'-aminobenzyl) aniline and their mixtures. Preferred polyamines are l-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (isophorone diamine or IFDA), bis (4-aminocyclohexyl) methane, bis (4-amino-3-methyl-clohexyl) methane, 1,6-diaminohexane, 2-methylpentamethylenediamine, ethylenediamine, triaminononane, 2,4- and / or 2, 6- toluylene diamine and 4,4'- and / or 2,4'-diaminodiphenylmethane. Suitable polyamines of high molecular weight include those prepared from known polyhydric polyhydroxy compounds, especially polyethers. The polyamines can be prepared by reacting the polyhydroxyl compounds with an excess of the polyisocyanates previously described to form NCO prepolymers and subsequent hydrolysis of the terminal isocyanate group to an amino group. Preferably, the polyamines are prepared by converting the terminal hydroxy groups of the polyhydroxyl compounds into amino groups, for example by amination. Preferred high molecular weight polyamines are amine terminated polyethers such as Jeffamine Texaco resins. The preparation of the polyaspartates from the aforementioned starting materials can be carried out, for example, at a temperature of 0 to 100 ° C, using the starting materials in such proportions that at least 1, preferably 1, is present. , olefinic double bond for each primary amino group. The excess of the starting materials can be removed by distillation after the reaction. The reaction can be carried out solvent-free or in the presence of suitable solvents, such as methanol, ethanol, propanol, dioxane and mixtures of said solvents. The compositions according to the invention may also contain known additives, such as fillers, plasticizers, pigments, carbon black, silica sols, leveling agents, wetting agents, antifoaming agents and stabilizers. To prepare the two-component coating compositions according to the invention, the isocyanate and aspartate components and the optional additives can be mixed with water in any particular order. Preferably, the aspartate component is mixed with any additive and then with the isocyanate component. The resulting mixture is then dispersed in water in a known manner with simple mixing. However, it is also possible to introduce one of the reactive components, preferably the aspartate component, with water and then introduce the remaining component. The isocyanate and aspartate components are mixed in amounts corresponding to a minimum equivalent ratio of isocyanate groups to amino groups of 0.9: 1, preferably 1.7 and, more preferably, 4: 1, and a maximum equivalent ratio of 20: 1, preferably 12: 1. If coatings having a better chemical resistance are desired, then higher NCO: NH equivalent ratios are used. The flexibility / hardness of the coatings can be altered, for example, by selection of the polyamine used to prepare the aspartate.
The resulting compositions have a minimum solids content of 20% by weight, preferably 50% by weight and, more preferably, 70% by weight. The maximum solids content is 96% by weight, preferably 95% by weight and, more preferably, 90% by weight. The solids contents of the two-component compositions according to the invention are much greater than those of the one-component and two-component polyurethane dispersions, which typically have solids contents of 35 to 40% by weight. Depending on the solids content and the presence of organic solvents, the coating compositions according to the invention are present in oil-in-water or water-in-oil emulsions. In addition to the binder components, the coating compositions may also contain the known coatings technology additives, such as fillers, pigments, softeners, high-boiling liquids, catalysts, UV stabilizers, antioxidants, microbicides, algicides, dehydrators. , thixotropic agents, wetting agents, flow enhancers, delustrant agents, anti-slip agents, aerators and extenders. The additives are chosen based on the requirements of the particular application and its compatibility with components a) and b). The coating compositions can be applied to the substrate to be coated by conventional methods, such as painting, rollers, pouring or spraying. The invention is still illustrated, but without intending to limit it, by the following examples, wherein all parts and percentages are by weight, unless otherwise specified. EXAMPLES The following starting materials were used in the examples: The hydrophilically modified polyisocyanates were prepared by reaction of the monofunctional polyethers described below with an IHR trimer, i.e., a polyisocyanate containing isocyanurate groups prepared by trimerization of a portion of the isocyanate groups of 1,6-hexamethylene diisocyanate, containing tris (6-isocyanatohexyl) isocyanurate and higher homologs thereof and having an isocyanate content of 21.6% by weight, a monomeric diisocyanate content of < 0.2%, a viscosity at 20 ° C of 3000 mPa.s and an average isocyanate functionality of about 3.5. The amount of monofunctional polyether reacted with the polyisocyanate in percent by weight, based on the weight of the polyisocyanate, is set forth in the Table. The reaction was carried out under nitrogen and with stirring, until the theoretical isocyanate content was obtained, which occurred, in general, after 2 to 3 hours. When the reaction was completed, the reaction product was cooled and stored under dry nitrogen. Polyisocyanate 1 A modified polyisocyanate was prepared by reacting a DIH trimer (Desmodur 3300, from Bayer Corp.) with a monofunctional polyether prepared by ethoxylation of methanol and having a molecular weight of 350. The modified polyisocyanate contained 12.3% of the polyether. Polyisocyanate 2 A modified polyisocyanate was prepared by reaction of the DIH trimer described above with a monofunctional polyether having a molecular weight of 2150 (number of OH-26.2) and prepared by alkoxylation of n-butanol with a mixture of ethylene oxide and propylene oxide (molar ratio of ethylene oxide to propylene oxide - 83:17). Polyisocyanate 3 A polyisocyanate modified by reaction of the DIH trimer described above was prepared with a monofunctional polyether having a molecular weight of 630 and prepared by alkoxylation of n-butanol with a mixture of ethylene oxide and propylene oxide (molar ratio of ethylene to propylene oxide - 99: 1). Polyaspartate 1 238 parts of 4,4'-diamino-3,3 '-dimethyldicyclohexylmethane (available from BASF as Laromin C 260) (1.0 mole) were added dropwise with stirring to 344 parts of maleic acid diethyl ester (2)., 0 moles) that had been previously charged at room temperature in a three-neck 1 L flask equipped with a stirrer, a thermometer and an addition funnel. The amine was added at such a rate 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, which was reduced to 90% solids with n-butyl acetate, was a clear, colorless liquid having a viscosity of about 300 mPa.s (25 ° C) and an equivalent weight of about 291, base to the solids. Poliaspartate 2 516 parts of maleic acid diethyl ester (3.0 moles) were added dropwise with stirring to 403 parts (1.0 moles) of an amine-terminated, trifunctional propylene oxide polyether (Jeffamine T-403, Texaco) that had been previously charged at room temperature in a 2 L, three neck flask equipped with stirrer, thermometer and addition funnel. The diester was added at such a rate that the exotherm did not increase the temperature of the reaction mixture above 50 ° C. After completion of the addition, 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 having a viscosity of about 96 mPa.s (25 ° C) and an amine equivalent weight of about 306. Additive 1 A tribrach and foam control additive (FC) -430, of 3M) present as a 5% solution in butylcarbitol. Additive 2 A setting agent (Victawet 35B, from Stouffer). Additive 3 A molecular sieve (Baylith L powder, from Bayer Corp.). Examples 1-19 Coating compositions were prepared by mixing the polyaspartates with any additive. Unless otherwise indicated, the resulting mixture was mixed with the isocyanate and then with water to form the aqueous coating composition. In certain examples, the polyaspartates were mixed with water before the addition of the isocyanate. In the comparative examples, the coating compositions did not contain water. The coating compositions were applied to steel panels and glass substrates in a wet film thickness of 3 mils and cured for two weeks at 25 ° C and 55% relative humidity. The results are shown in the following tables.
Table 1 These examples demonstrate that the coatings obtained from the coating compositions according to the invention are virtually the same as those obtained from the known compositions of two components, which do not contain water. Therefore, the use of water as a solvent according to the present invention does not have a detrimental effect on the properties of the resulting coatings. Table 2 This example demonstrates that even when the coating compositions are cured at below ambient temperatures, the resulting coatings possess properties comparable to those obtained at room temperature. This is not typical of aqueous two component coating compositions containing a polyisocyanate and a polyol component.
Table 3 Table 3 (cont.) Table 4 Table 4 (cont.) Table 5 Table 5 (cont.) The Gardner drying time was determined using a Gardner Circular Drying Time Recorder. Hard to touch - During the first stage of drying, the film is mobile and partially flows back into the striped channel. The film can be considered "stable to the touch" when it no longer backfolds and the stylus begins to leave a transparent channel. Dry on the surface - When the stylus no longer leaves a transparent channel, but begins to break the dry top layer of the curing film, the film is considered "dry on the surface". Dries hard - When the stylus no longer breaks the film, but moves freely on the surface, it can be considered that the cross section of the film has reached the condition of "hard dry". Wear-free - When the stylus no longer wears the surface of the film at all, it can be considered that the film is "wear-free". The resistance to solvents was determined by wetting a gauze with methyl ethyl ketone and then rubbing each panel 100 times. A double rubbing consists of rubbing from one part to another against the coated panel. Following a waiting period of five minutes after the friction was completed, each panel was scraped with the fingernail of the big toe. If there was no evidence of destruction of the film, the films were rated as apt. The pendular hardness of the coatings was determined according to ASTM D-4366-87 (Koenig Pendular Hardness). The abrasion resistance was determined according to ASTM D-4060 (wheels CS 17, 1000 cycles and 1000 g of weight in each cycle). The impact resistance was determined according to ASTM D-2794.
Resistance to chemical stains was determined by placing a drop of the particular liquid on a coated panel and covering it with a 4-ounce glass jar. For those solvents that evaporate rapidly, a cotton ball was placed on the liquids of the coated panel and remained saturated. After the appropriate time interval, the coated panels were washed and evaluated to determine the effect of the liquid and assigned one of the following classifications: NE No effect A, R: Film softened, but recovered after 1 hour A: Film softened B: Film with bubbles. D: Destroyed movie. Although the invention has been described in detail in the foregoing for illustrative purposes, it is to be understood that said detail has only that purpose and that those skilled in the art can make variations therein without departing from the spirit and scope of the invention, except in what may be limited by the claims.

Claims (18)

  1. CLAIMS 1. An aqueous coating composition having a solids content of 20 to 96% by weight and consisting of a) a polyisocyanate dispersible in water and having an average NCO functionality of 2 to 6 and b) a corresponding polyaspartate to the formula X- -N where X represents an organic group having a valence of n and is inert towards the isocyanate groups at a temperature of 100 ° C or less; R? and R 2 may be the same or different and represent organic groups that are inert towards the isocyanate groups at a temperature of 100 ° C or less, or R? and R2, together with the β-carbon atom, form a cycloaliphatic or heterocyclic ring; R3 and 4 may be identical or different and represent hydrogen or organic groups which are inert toward the isocyanate groups at a temperature of 100 ° C or less, and n has a value of 2 to 6 and c) water, which is present in an amount of at least 4% by weight based on the solids content of components a) and b), where components a) and b) are present in an amount sufficient to provide an equivalent ratio of isocyanate groups to amino groups of at least 0, 9: 1.
  2. 2. The composition of Claim 1, wherein said polyisocyanate is based on a polyisocyanate adduct containing isocyanurate groups.
  3. 3. The composition of Claim 2, wherein said polyisocyanate adduct is prepared from 1,6-hexamethylene diisocyanate.
  4. 4. The composition of Claim 1, wherein said X represents the group obtained by elimination of the amino groups of 4,4 '-diamino-3,3' -dimethyldicyclohexylmethane.
  5. 5. The composition of Claim 2, wherein said X represents the group obtained by removing the amino groups of 4,4 '-diamino-3,3' -dimethyldicyclohexylmethane.
  6. 6. The composition of Claim 3, wherein said X represents the group obtained by elimination of the amino groups of 4,4 '-diamino-3,3' -dimethyldicyclohexylmethane. The composition of Claim 1, wherein said X represents the group obtained by elimination of the amino groups of an amino-terminated polyether. 8. The composition of Claim 2, wherein said X represents the group obtained by elimination of the amino groups of an amino-terminated polyether. 9. The composition of Claim 3, wherein said X represents the group obtained by elimination of the amino groups of an amino-terminated polyether. 10. An aqueous coating composition having a solids content of 20 to 96% by weight and consisting of a) a polyisocyanate dispersible in water and having an average NCO functionality of 2 to 6 and b) a polyaspartate corresponding to the formula where X represents an organic group having a valence of n and is inert towards the isocyanate groups at a temperature of 100 ° C or less; R? and R 2 may be the same or different and represent organic groups which are inert towards the isocyanate groups at a temperature of 100 ° C or less, or R x and R 2, together with the β-carbon atom, form a cycloaliphatic or heterocyclic ring; R3 and R4 may be identical or different and represent hydrogen or organic groups that are inert towards the isocyanate groups at a temperature of 100 ° C or less, and n has a value of 2 to 6 and c) water, which is present in an amount of at least 4% by weight based on the solids content of components a) and b), where components a) and b) are present in an amount sufficient to provide an equivalent ratio of isocyanate groups to amino groups of at least 1, 7: 1 The composition of Claim 10, wherein said polyisocyanate is based on a polyisocyanate adduct containing isocyanurate groups. The composition of Claim 11, wherein said polyisocyanate adduct is prepared from 1,6-hexamethylene diisocyanate. The composition of Claim 10, wherein said X represents the group obtained by removal of the amino groups from the group., 4'-diamino-3, 3 '-dimethyldicyclohexylmethane. The composition of Claim 11, wherein said X represents the group obtained by removal of the amino groups of 4,4 '-diamino-3,3' -dimethyldicyclohexylmethane. 15. The composition of Claim 12, wherein said X represents the group obtained by removal of the amino groups of 4,4 '-diamino-3,3' -dimethyldicyclohexylmethane. 16. The composition of Claim 10, wherein said X represents the group obtained by elimination of the amino groups of an amine-terminated polyether. The composition of Claim 11, wherein said X represents the group obtained by elimination of the amino groups of an amine-terminated polyether. 18. The composition of Claim 12, wherein said X represents the group obtained by elimination of the amino groups of an amine-terminated polyether.
MXPA/A/1997/010184A 1996-12-17 1997-12-16 Compositions of depoliurea waterproof of two components MXPA97010184A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US08766136 1996-12-17
US08/766,136 US5736604A (en) 1996-12-17 1996-12-17 Aqueous, two-component polyurea coating compositions

Publications (2)

Publication Number Publication Date
MX9710184A MX9710184A (en) 1998-06-30
MXPA97010184A true MXPA97010184A (en) 1998-10-30

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