COATING COMPOSITIONS CONTAINING A KETIMINE

Abstract: Coating compositions comprising polymeric com­ pounds containing aliphatic isocyanate groups and keti­ mines of di- and polyamines in a non-reactive solvent cure slowly in the presence of moisture to provide hard, tough, solvent-resistant surface coatings.

Description: COATING COMPOSITIONS CONTAINING A KETIMINE FIELD OF THE INVENTION This invention relates to surface coatings containing urethane groups. More particularly, it relates to two-component polyurethane surface coatings curable at room temperature. Such compositions provide moisture-hardening-type coatings which excel.in weather resistance and flexibility and which do not develop coating film defects such as foaming even under an environment of high humidity. The compositions have long pot lives. BACKGROUND OF THE INVENTION Heat-curable polyisocyanate compositions provide polyurethanes on curing into decorative and protective coatings, but, especially for large objects (e.g., automobile repair, industrial maintenance coatings), it is impractical to subject the coated structure to oven baking to effect good cure. Room temperature curing of polyurethane surface coating is known, in particular polyurethane surface coatings derived from aliphatic isocyanates. However, these are normally of low reactivity so it is difficult to achieve good room temperature cures with coatings containing this class of isocyanates. Moreover, polyurethane coating materials have rather poor weather resistance when aromatic isocyanates are used, and hardening speed at room temperature is slow if aliphatic or alicyclic isocyanates are used for the purpose of improving the weather resistance. Furthermore, if a catalyst is used tc increase hardening rate, reaction between moisture in the air and the isocydnate occurs and coating film defects such as foaming develop, and pot life is shortened. Thus, there is a major need to provide improved compositiors containing a' phatic NCO groups. The present invention provides such mproved compositions in a novel manner. SUMMARY OF THE INVENTION According to the present invention, in its broadest aspects, a low polymer (a), molecular weight preferably between about 400 and 6000, containing an aliphatic isocyanate (NCO) group or groups, is mixed with (b) a ketimine of a di- or polyamine in a solvent which dissolves both reactants but which, itself, is non-reactice to NCO. Thereafter, if desired, a film is cast and the solvent is allowed to evaporate at any desired temperature preferably room temperature, e.g., 20 - 250C. Then the ketimine slowly liberates di- or polyamine, which effects cure and provides for formation of hard, tough, solvent-resistant surface coatings. A preferred embodiment of the invention is a moisture-hardening-type composition, which is obtained by compounding; (a) a polyester polyurethane resin or poly ether polyurethane resin which possesses nonaromatic isocyanate groups and, (b) a ketimine compound where at least one of the amino groups of a polyamine com pound which contains at least two primary amino groups in one molecule has been blocked by reaction with a ketone. A more particularly preferred embodiment of this invention is a coating composition which is obtained by compounding, (a) an isocyanate-group-containing copolymer which is obtained by copolymerizing 2 to 50 mole % of a monomer which possesses the structure of general formula, EMI4.1 (in the formula, R is hydrogen or an alkyl group, n is an integer of 1 or 2), any 98 to 50 mole % of an ethylenic unsaturated monomer which is copolymerizable with the above-mentioned monomer, and, - (b) a ketimine compound where at least one of the amino groups of polyamine compound which contains two or more primary amino groups in one molecule has been blocked by reaction with a ketone. The latter composition possesses a long usable time in a system where water is absent. On the other hand when it has been coated onto the article to be protected, it reacts with moisture from the air and immedi- matey undergoes a hardening reaction.. In such compositics there is excellent balance between the usable time and hardening rate and, at the same time, protective filths can be formed which are outstanding in weather resistance and flexibility. DETAILED DESCRIPTION OF THE INVENTION In the broadest aspect, polymeric isocyanate (a) may be any adduct of a di- or polyisocyanate, preferably with a stoichiometric insufficiency of a polyol, preferably a diol or triol, or of a hydroxyl-containing polymer, such as an acrylic polymer, a polyester, or a polyether reacted with about one mole of a diisocyanate (NCO) per equivalent of hydroxyl (OH)s. Likewise, broadly, the ketimine (b) may be derived from the reaction of a di- or polyamine, preferably an aliphatic polyamine, having at least two primary amino (-NH2) groups, e.g., ethyllenediamine, 1,6-hexanediamine, and any ketone, for example, acetone, methyl ethyl ketone and the like. Optionally, water formed in the reaction EMI5.1 can be removed to improve pot life. Polyols suitable for preparing prepolymer component (a) include monomer polyols, such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, trimetbylene glycol, 1,3- and 1,4-butanediol, 1,5-pentanediol, 1,2hexylene glycol, l,10-decandeaiol, 1,2-cyclohexanediol, 2-butene-1,4-diol, 3-cyclohexane-1,1-dimethanol, 4methyl-3-cyclohexane-1,1-dimethanol, 3-methylene-1,5pentanediol, (2-hydroxyethoxy) -1-propanol, 4- (2-hydroxy- ethoxy)-1-butanol, 5-(2-hydroxypropoxy)-1-pentanol, 1-(2hydroxy-methoxy) 2-hexanol, 1-(2-hydroxypropoxy)-2-octanol, 3-allyloxy-1,5-pentanediol, 2-allyloxymethyl-2-methyl1,3-pentanediol, [(4,4-pentyloxy)-methyl]-1,3-propanediol, 3-(o-propenylphenoxy)-1,2-propanediol, 2,2'-diisopropylidene-bis-(p-phenyleneoxy)diethanol, glycerin, 1,2,6hexanetriol, 1,1,1-trimethylolethane, 1,1,1-trimethylol propane, 3-(2-hydroxyethoxy)-1,2-propanediol, 3-(2hydroxypropyl)-1,2-propanediol, 2,4-diamethyl-2-(2hydroxyethoxy)-methyl-pentanediol-1,5, 1,1,1-tris [(2-hydroxyethoxy) methyl]ethane, 1,1,1-tris [(2hydroxypropoxy)methyl]propane, pentaerythritol, sorbitol, sucrose, lactose, &alpha;-methyl glucoside, a-hydroxyalkyl glucosides, novolac resins, hydroxy-terminated caprolactose, and the like. Preferred is 1,1, l-trimetbylolprcpane. The compositions containing polyester polyurethane and/or polyether polyurethane resins having nonaromatic (i.e., aliphatic) isocyanate groups are obtained by polycondensing a hydroxyl-containing polyester or polyester with a polyisocyanate in excess. Illustrative hydroxyl terminated polyesters are reaction products of polyhydric alcohols, such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,4butanediol, 1,3-butanediol, pentanediol, 1,6-hexanediol, dodecanediol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, neopentyl glycol, 2,2,4trimethylpentanediol, hydrogenated bisphenol A, propylene oxide addition product of bisphenol A, glycerin, tri- methylolethane, trimethylolpropane, pentaerythritol, and trishydroxyethyl isocyanurate, and a polycarboxylic acid, polycarboxylic acid anhydride, or alkyl ester of a polycarboxylic acid, such as phthalic anhydride, isophthalic acid, terephthalic acid, dimethyl terephthalic acid, succinic acid, adipic acid, azelaic acid, dodecanedioic acid, eicosanedioic acid, dimer acid, maleic anhydrice, fumaric acid, itaconic acid, tetrahydrophthalic acid, anhydrous hexahydrophthalic acid, Eymic acid anhydride, methyl Nadic acid anhydride, trimellitic anhydride, pyromellitic anhydride, and butanetetracarboxylic acid, in a mixing proportion where the hydroxyl groups are in excess. Also permissible in combination are, e.g., monobasic acids such as fatty acids, benzoic acid, and tertiary butyl benzoic acid, monoalcohols such as octanol, lauryl alcohol, and oleyl alcohol, hydroxycarboxylic acids such as hydroxystearic acid, parahydroxybenzoic acid, and metahydroxybenzoic acid. In addition, polycaprolactone, which is a ring-opened, hydroxy-terminated polymer of s-caprolactone, is extremely useful. Although the number-average molecular weight of the above-mentioned hydroxyl-group-terminated polyester can vary widely, the range of 200 to 5,000 is preferred and it is especially preferred that it be a low molecular weight substance of 300 to 2,000. As the aforementioned hydroxyl-terminated polyether, there can be used,e.g., polyoxyethylene, polyoxypropylene, polyoxyethylene propylene copolymer polyether, and polytetramethylene glycol, and the like. In addition to simple linear polyethers, polyfunctional polyethers which possess at least 3 hydroxyl groups at the molecular terminal, with a branched structure possessing a polyhydric alcohol such as glycerin or pentaerythritol, or a polyamine such as ethylenediamine in the skeleton, can be used. Hydroxy-functional polymers of other types can be used also, especially the hydroxy poly methacrylates. These are available coirmer- cially, or can be made in known ways. Especially useful is a commercial hydroxyl-containing polyacrylate available from Henkel, under the trade?ame G-Cure 867. The isocyanate stating material comprises a compound wherein the isocyanate group is not directly bonded to an aromatic ring. Aromatic groups are permitted elsewhere in the structure, however. Illustratively included are alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate (MDI), hydrogenated toluene-diisocyanate (TDI), hydrogenated xylene diisocyanate, and the like; aliphatic polyisocyanates, such as hexamethylene diisocyanate, lysine diisocyanate, and the like, and, in addition, aromatic ring-containing polyisocyanates wherein the NCO group is not directly bonded to the aromatic ring, such as xylene diisocyanate, a,z,a','- tetramethyl xylylene diisocyanate, &alpha;,&alpha;,&alpha;',&alpha;'-tetramethyl- naphthylene diisocyanate, and the like. Isocyanates wherein the NCO's.are directly bonded to aromatic rings, such as toluene diisbcyanate,-diphenylmethane diiso- cyanate, naphthylene diisocyanate, and the like, are not suitable for this invention. Preferred compounds have isocyanate groups bonded to secondary or tertiary aliphatic carbon atoms. Especially preferred is a,a,a' ,a '- tetramethyl-meta-xylylene diisocyanate (also known as m-TMXDI). The low polymers (a) can have a molecular weight which varies broadly, but preferably it will be in the range of 400 to 10,000. The low polymers are obtained by condensing an excess of polyisocyanate with the hydroxy-compound; usually under heating at 40 to 1500 C, for example. The proportion of mixing the hydroxyl groups and isocyanate groups is conventional and well known, but usually in the range of 1:1.3 to 1:2.5 and preferably 1:1.5 to 1:2.0 (-OH to -NCO). In one aspect of the invention, monomers which possess the general formula structure, EMI9.1 wherein R is hydrogen or an alkyl, e.g., C1-Cs alkyl, and n is an integer of 1 to 2, can be mentioned, e.g., p-isopropenyl-,a-dimethylbenzyl isocyanate, p-ethylenyl a,a-dimethylbenzyl isocyanate, m-ethylenyl- dimethyl- benzyl isocyanate, isopropenyl-a, ,a',a'-tetramethyl- xylylene diisocyanate, ethylenyl-a,a,a',a'-tetramethy- xylyene diisocyanate, etc. The proportion of the isocyanate-group-containing monomers for the aforementioned copolymer is about 2 to 50 mole %, preferably, 5 to 40, and especially preferably, 10 to 30, mole t. Illustrative ethylenic unsaturated monomers which are copolymerizable with the aforementioned monomers, are acrylic acid esters, such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2ethylhexyl acrylate, lauryl acrylate, oleyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, 2hydroxyethyl acrylate, and 2-hydroxypropyl acrylate; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, oleyl methacrylate, stearyl methacrylate, methoxyethyl methacrylate, butoxyethyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate, aromatic vinyl monomers such as styrene, a-methyl- styrene, vinyltoluene, paramethylstyrene, and chlorostyrene, monoalkyl esters or dialkyl esters of unsaturated dibasic acids such as maleic acid, fumaric acid, or itaconic acid, nitrile-group-containing monomers such as acrylonitrile and methacrylonitrile, vinyl esters such as vinyl acetate and vinyl propionate, and unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, itaconic acid, and crotonic acid, mixtures thereof and the like. Among the above-mentioned various ethyleneic unsaturated monomers, acrylic acid esters and methacrylic acid esters are especially preferred; also, to combine the use of aromatic vinyl monomers in the amount of 0 to 30 weight % of. the total monomers with the acrylic acid ester or methacrylic acid ester improves gloss; also, to combine the use of a nitrilegroup-containing monomer in the amount of 5 to 30 weight % of the total monomers with the acrylic acid ester, methacrylic acid ester, or aromatic vinyl monomer is especially preferred to speed polymer formation. The isocyanates-group-containing copolymer preferably has a number-average molecular weight of 1,000 to 20,000. Synthesis is possible under the presence o z polymerization initiator which generates radicals in an inert solvent by either cf the solution polymerization method, bulk polymerization method, suspension polymerization method, and emulsion polymeriza- tion method, but the solution polymerization method or bulk polymerization method In a system where water is absent is especially preferred. The ketimine component (b) is one wherein at least one of the amino groups of a polyamine compound which possesses at least two primary amino groups has been capped by reaction with a ketone. These can be obtained by effecting dehydration reaction of an aliphatic amine such as ethylenediamine, trimethylenediamine, tetramethylenediamine, 1, 6-hexamethylenediamine, nonamethylenediamine, and diethylenetriamine, alicyclic diamines such as isophoronediamine, 4,4'-bisaminomethylcyclohexane, 4,4'-diaminodicyclohexylpropane, hydrogenated xylylenediamine, and dipentenediamine, an alicyclic diamine such as a,z,a',a'-tetramethylxylenediamine, or a diamine where the amino group is not directly bonded to the aromatic ring, such as a,a,a',a'-tetramethylxylylenediamine and xylylenediamine, with a ketone such as acetone; methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone-, and isophorone. It is preferred that all of the amino groups of a polyamine compound be ketimized, but only can one amino group in the molecule need be reacted. The ketimine compound (b) is a latent amino compound which releases ketone in the presence of moisture and reverts to an amine, and it does not react with the aforementioned component (a) in a coating material where water is not present, but when it has been coated on a surface to be covered, the ketimine reacts with moisture from the air and reverts to the amine, which forms a tough crosslinked covering film by immediately reacting with the isocyanate groups in the polymer (a). The isocyanate-group-containing polymer (a) and the ketimine compound (b) are mixed and used in weight proportions such that an equivalent quantity of the isocyanate groups of (a) and an equivalent quantity of the amino groups (total of ketimine and free amino groups) of the ketimine compound (b) are within the range of 1:..06 to 1: 1.2, and especially preferably 1: 0.7 to 1: 1(-NCO to -NH2). The aforementioned isocyanate-group-containingpolymer (a) and ketimine compound (b) are usually used by dissolving them in an organic solvent which does not contain water or active hydrogen. Suitable solvents are widely available. Illustratively, esters such as methoxyethyl acetate, toluene, -and the like, can be employed. Besides being provided for actual use as a clear varnish, they can have mixed and dispersed therein various types of inorganic pigments for coloring, such as titanium oxide, iron oxide, carbon black, and phthalocyanine blue, inorganic fillers such as calcium carbonate, barium sulfate, talc, alumina, silica, glass fibers, bentonite, and also processing aids such as leveling aids, defoaming aids, and dispersing aids. Coatings produced from the moisture-hardeningtype compositions according to this invention excel in hardening properties in spite of the fact that the usable time is long. They do not develop coating film defects such as foaming even under an environment of high humidity. In ad i.ion, the coating films excel in weather resistance and flexibility, and they can be used widely for products made of metal, wood, plastic, and cement, as well as for pre-formed organic covering films and the like. DESCRIPTION OF THE PREFERRED EM3ODIYiENTS The following non-limiting examples illustrate the invention: Xetimines were prepared in a known manner by reacting a ketone, e.g., acetone or methyl isobutyl ketone, with a polyamine, e.g., ethylenediamine, 1,6hexamethylenediamine, or 1,4-bis(aminomethyl)-cyclo- hexane in toluene as a solvent. The water of reaction was optionally removed, after a few hours of heating the mixture at about 80 C, or, after several days of standing at room-temperature, by treatment with a molecular sieve. Prepolymer A A mixture Gf 300.4 g (1.23 moles) m-TMXDI, 50 g (0.373 mole) trimethylolpropane and 0.015% dibutyltin dilaurate (on total charge) was heated for 4 h at 800C under dry nitrogen, to provide an adduct or prepolymer containing 15.9% NCO. Precolvmer B A mixture of 259 g (1.06) p-T!XDI, 500 g (0.515 mole) poly(tetramethylene ether) glycol of numberaverage molecular weight 970, and 0.010% dibutyltin dilaurate (on total charge) was heated. for 4 h at 800C under dry nitrogen to provide a prepolymer containing 5.9% NCO. Examples 1-5 To provide coating compositions, the prepolymers prepared as shown above were diluted with methoxy ethyl acetate solvent and mixed with a ketimine, or for control purposes with the corresponding amine. The ratio of NCO equivalents to amine equivalents (actually present in the amine or potentially available from the ketimine) was about 1 : 0.95 in each case. Where the mixture had sufficient pot life, films were cast from it. The formulations used and the results obtained are set forth in Table 1. TABLE 1: COMPOSITIONS OF ISOCYANATE-GROUP-CONTAINING PREPOLYMER AND KETIMINE EXAMPLE 1A* 1 2 3A* 3 4 5A* 5 COMPOSITION (parts by weight) Prepolymer of 37.4 pbw &alpha;,&alpha;,&alpha;',&alpha;-tetramethyl-meta-xylylene diisocyanate and 62.6 pbw polytetramethylene ether glycol 100 100 100 100 100 100 100 100 Ethylenediamine 6.54 - - - - - - Ethylenediamine/acetone ketimine (water not (removed) - 19.2 - - - - - Ethylenediamine/acetone ketimine (water removed) - - 15.3 - - - - 1,6-hexanediamine - - - 7.7 - - - 1,6-hexanediamine/acetone ketimine (water not removed) - - - - 15.4 - - 1,6-hexanediamine/acetone ketimine (water removed) - - - - - 21.1 - - 1,4-bis(aminomethyl)cyclohexane - - - - - - 9.5 1,4-bis(aminomethyl)cyclohexane/acetone ketimine (water removed) - - - - - - -14.8 PROPERTIES Pot Life (min.) 1.5 1.5 4.5 0.17 0.25 25 0.2 25 Dry-to-Touch Time (min) no film 90 180 no film 5 90 no film 90 * Control. The data in Table 1 demonstrate that if the free amine, instead of the ketimine,was used, the pot life of the composition was so short as to make the preparation of coating films impractical. On the other hand, with the ketimines, particularly those from which the water of reaction has been removed, reasonable pot lives are obtained and films were obtained which were dry to touch in not over three hours at room temperature. EXAMPLES 6-8 A prepolymer was prepared from a,a,a' , - tetramethyl-metaxylylenediisocyanate (m-TMXDI) and a commercial hydroxyl-containing polyacrylate, G-Cure 867, (Henkel Company)by reaction of the two materials in the proportions of one mole of m-TMX2I for each equivalent of OH in the polyacrylate. Conditions and catalyst were as in Examples 1-5. Portions of the solution were mixed with a toluene of the respective ketimine in the proportion of one ketimine nitrogen for each equivlanet of NCO in the m-TMXDI- reacted prepolymer. The formulations used and the results obtained are set forth in Table 2: TABLE 2: COMPOSITIONS OF ISOCYANATE-CONTAINING-POLYMER AND KETIMINES EXAMPLE 6 7 8 COMPOSITION(parts by weight) &alpha;,&alpha;,&alpha;',&alpha;'-tetramethyl-meta-xylylene diisocyanate prepolymers with hydroxyfunctional polyacrylate 84.0 81.1 89.0 1,4-bis(aminomethyl)cyclohexane/acetone ketimine 16.0 - 1,6-hexamethylenediamine/methylisobutyl ketone ketimine - 18.9 Ethylenediamine/acetone ketimine - - 10.7 Modaflow (flow promoter) a - 0.5 0.5 Cellulose acetate butyrate,b - 0.5 0.5 Solvent PROPERTIES Pot Life (minutes) 2.5 2.0 1.0 Dry-to-touch (minutes) 5.0 3.0 2.0 Film Properties, 1 week cure at 23 C. Thickness, mil 1.0 1.0 1.0 Pencil hardness H-2H H-2H H-2H 60 Gloss 41 133 114 Methylethyl ketone, rubs to remove 200 50 < 200 Tape removal adhesion (0 to 10 (perfect)) 7 7 7 a. parts of a 10% solution in toluene b. parts by a 20% solution in methyl ethyl ketone. EXAMPLES 9-14 A prepolymer was prepared from &alpha;,&alpha;,&alpha;'&alpha;'- tetramethyl-meta-xylylenediisocyanate and a polycaprolactone of m.w. 1000 by the general procedure used to make Prepolymer B above and designated PCL-TMXDI. A prepolymer of m-TMXDI and 1,1, 1-trimethyloipropane was made in a similar manner by reacting the two materials in a molar ratio of 3:1, and designated TMP-TMXDI. Various proportions of the prepolymers were mixed, and combined with the ketimine of ethylenediamine and acetone (water removed) described above, in the proportions of one equivalent of ketimine nitrogen for each equivalent of NCO groups. The final mixtures were diluted to 50% solids'in methoxyethyl acetate to provide a coating composition. The composition was drawn into films on aluminum test panels. These were allowed to stand for two weeks at room temperature before testing. The formulations used and the results obtained are set forth in Table No. 3. TABLE NO. 3: COMPOSITIONS OF ISOCYANATE-CONTAINING-PREPOLYMERS AND KETIMINES EXAMPLE 9 10 11 12 13 14 (Composition (equivalents) Prepolymer 1 1 1 1 1 1 PCL-TMXDI (pbw) (100) (90) (70) (50) (30) (0) TMP-TMXDI (pbw) (00 (10) (30) (50) (70) (100) Ketimine of ethylene diamine/acetone 1 1 1 1 1 1 PROPERTIES Pot Life (min.) > 60 > 60 30 10 < 12 < 2 Dry-to-touch time (min.) ND ND 45 20 12 2 Film Propertis Thickness, mils 0.8 0.7 0.8 0.8 0.7 0.7 Pencil hardness F-H H-2H 2H-3H 2H-3H 2H-3H 3H-4H Revrse impact resistance, in-lb. > 78 > 78 60 70 > 70 > 50 Mendrel flex, 1/8., P-pass, F-fail P P P P P F Adhesion by tape test (0-10 (perfect) 10 10 10 10 10 10 The results in Table 3 show that by suitable adjustment of functionality in the composition it is possible to obtain good hardness and flexibility and yet achieve good solvent resistance as well, together with other valuable properties and good curing at reasonable times at room temperature. PREPARATION 1 A trifunctional-type polycaprolactone of molecular weight 550, made by Daicel Chemical Industries, No. 305, 550 parts by weight, 594 parts by weight of isophorone diisocyanate, and 763 parts by weight of ethyl acetate as solvent were added to a reactor which was equipped with a reflux condensing tube, stirrer, and thermometer, and then heated and mixed at 906 C for 7 hours. There was obtained a 60 weight % solution of an isocyanate-terminated polyester polyurethane resin. The quantity of isocyanate groups was 1.26 equivalents in 1000 g. of solution. PREPARATION 2 A mixture of 690 parts by weight of a terminal hydroxyl group polyester resin of 1,4-butanediol and adipic acid (number-average molecular weight 690), 134 parts by weight of trimethylolpropane, and 854 parts by weight of a,a,a1,a'-tetramethylmetaxylylene diisocyanate was added to the reactor of preparation 1, then after heating at 1200 C for 5 hours. This was diluted by adding 560 parts by weight of ethyl acetate and 560 parts by weight of toluene. There was obtained a 60 weight % solution of an isocyanate-terninated polyester polyurethane resin. The quantity of isocyanate groups was 0.72 equivalents in 1000 g. of solution. PREPARATION 3 A mixture of 1000 parts by weight of poly tetranethylene glycol of molecular weight 1000, 171 parts by weight of trishydroxyethyl isocyanurate, 168 parts by weight of hexamethylene diisocyanate, and 750 parts by weight of hydrogenated diphenylmethane diisocyanate H12 (MDI) was added to the reactor 7khich was used in Preparation 1, then after reacting at 80 C for 2 hours while heating and stirring and further at 1200 C for 3 hours, this was diluted by adding ethyl acetate 745 weight parts and toluene 745 weight parts, there was obtained a 60 weight % of an isocyanateterminated polyether polyurethane resin. The quantity of isocyanate groups was 1.44 equivalents in 1000 g. of solution. PREPARATION 4 A mixture of 400 parts by weight of a polypropylene glycol of a mixture of molecular weight 400, 530 parts by weight of a linear polycaprolactone of molecular weight 530 (trade number 205, made by Daicel Chemical Industries, Ltd.), and 981 parts by weight of &alpha;, &alpha;, &alpha;', &alpha;', &alpha;",&alpha;"-hexamethylmesitylene triisocyanate was added to the reactor which was used in Preparation 1, tnen reaction was carried out at 120 C for 5 hours and tis was diluted by adding methyl ethyl ketone 635 g and twluene 635 g. There was thereby obtained a 60% weight solution of an isocyanated-terminated polyurethane resin which possessed both a polyether and polyester skeleton. The quantity of isocyanate groups was 1.57 equivalent in 1000 g. of solution. PREPARATIONS 5-8 The repective polyamines, ketones, and other raw materials of Preparations 5-8 which are given in Table 4 were charged into a reactor which was equipped with a stirrer, a condenser with a water separating apparatus, and a thermometer, and reaction was conducted for 8 hours at 110 to 1150C in the case of 5-7 and at 750C in the case of 8. In the case of Preparation 5-7, the solvent was refluxed and the water which formed was separated and removed; and in the case of Preparation 8, the formed water was removed by causing it to become adsorbed by a molecular sieve, and by filtering the molecular sieve off after the reaction. The reaction products of the respective preparations were further concentrated under. reduced pressure and were so adjusted as to obtain a 50 weight % solution. Conversion to ketimine was measured by nuclear magnetic resonance analysis, and the total amino group content quantity (the total of ketimine and free amino groups is expressed as the number of equivalents in 1000 g. of solution) of the respective reaction product solutions was measured by the hydrochloric acid titration method. The results are presented in Table 4. TABLE 4: PREPARATION OF KETIMINES PREPARATION 5 6 7 8 COMPOSITION (parts by weight) Ethylenediamine 60 - Hexamethylenediamine - 116 Isophoronediamine - - 169 Hydrogenated xylylenediamine - - - 142 Methyl isobutyl ketone 500 500 500 Methyl ethyl ketone - - - 360 Toluene 100 100 100 Molecular sieve - - - 100 Ketimine conversion rate (mol %) 96 94 58 80 Amine content of 50% solution (equivalent 1 1000 g) 4.59 3.70 3.79 4.39 FEaS LES 15-23 The following general procedure was used for the coating composition. To 167 parts by weight of the respective isocyanated-terminated polyurethane resin solutions which were prepared in Preparations 1 to 4, were added, titanium oxide, 100 parts by weight, toluene, 83 parts by weight,ethyl acetate, 70 parts by weight, ethylene glycol monoethyl acetate, 30 parts by weight, and a silicone system leveling agent 0.1 parts by weight, then dispersing was effected with a sand mill for 1 hour, after which the resulting product was removed. There were obtained pigment dispersions of isocyanate-terminated polyurethane resins. Next, to 45 parts by weight of the respective above-mentioned pigment dispersions were added to the respective ketimine compound solutions of Preparations 5 to 8, given in Table 4, in the proportions of compounding given in Table 5. Thus were prepared the compositions for moisture-hardening-type coverings of this invention, Examples 15-23 of Table 5: : TABLE ISOCYANATE-CONTAINING PREPOLYMERS AND KETIMINES TYPE OF ISOCYANATE-TERMI- AMOUNT OF KETIMINE COMPOUND NATED POLYURETHANE RESIN SOLUTION COMPOUNDED EXAMPLE Preparation Preparation Preparation Preparation 5 6 7 8 15 Preparation 1 4.5 - 16 Preparation 1 - 5.1 - 17 Preparation 1 - - 5.5 18 Preparation 1 - - - 3.8 19 Preparation 2 - 3.2 - 20 Preparation 3 4.2 - - 21 Preparation 3 - 5.8 - 22 Preparation 4 - 7.0 - 23 Preparation 4 - - - 5.4 23A* Preparation 1 - not used - 23B* Preparation 2 - not used - 23C* Preparation 2 - 5.8 - * Comparison PREPARATION 1A A 60 weight % solution of the isocyanateterminated polyester resin which was produced in Preparation 1 was used to prepare a pigment dispersion by proceeding as outlined above; then, to 45 parts by weight of the pigment dispersion, was added 0.05 parts by weight of dibutylin dilaurate as a reaction accelerator; and a coating material of moisture-hardeningtype was prepared for comparison, (example 23A*, Table 5. PREPARATION 2A To 550 parts by weight of a trifunctional polycaprolactone of molecular weight 550, was added 470 parts of tolylene diisocyanate, and 680 weight parts of ethyl acetate as solvent in a reactor similar to that in Preparation 1, then the mixture was heated and mixed at 700 C for 6 hours. There was obtained a 60 weight % solution of an aromatic isocyanate-terminated polyester polyurethane. The content quantity of isocyanate groups was 1.42 equivalents in 1000 g. of solution. A pigment dispersion was prepared from this resin solution in exactly the same manner as described above, and a coating material of moisture hardening type was prepared for comparison (Example 23B, Table 5) by adding 0.05 parts by weight of dibutyltin dilaurate in 45 parts by weight of this pigment dispersion. PREPARATION 3A A comparison coating material of moisture hardening type (Example 23C* Table 5) was prepared by adding 5.8 parts by weight of the ketimine compound (solution of Preparation 6)to 45 parts by weight of the pigment dispersion which was prepared in Preparation 2A. The respective coating materials of Examples 15-23 and 23A-23C, given in Table 5, were spray-coated on tin sheets of ( > .3 mm thickness so that the dried coating film thickness would become about 30 V and, after drying. in a state of 25"C and relative humidity 60%, the physical properties of the coating films were judged. Also, these samples were left standing under an environment of 400 C and relative humidity 90% and the coating film sate condition was judged. Furthermore, the usable time of each coating material was examined. Each coating material was sealed into a glass bottle and the time to gelation at 250C was measured. The results of the foregoing evaluations are given in Table 6. TABLE 6: PROPERTIES Weather Hardening Property Coated Surface Coating Resis Gelling Time (25 C, 60% RH) State Under Pencil Film Elon- Gloss Tance EXAMPLE (hours) 8 hrs. 16 hrs. 24 hrs. High Humidityb Hardnessc gation d (60 ) Gloss Retention Rate e 15 60 50 < 50 < 50 < Good 3H 120% 92 84 16 52 50 < 50 < 50 < Good 2H 200% 95 84 17 60 40 < 50 < 50 < Good 3H 140% 95 86 18 32 50 < 50 < 50 < Good 3H 80% 95 86 19 96 32 50 < 50 < Good 2H 300% 97 87 20 48 50 < 50 < 50 < Good 3H 70% 95 82 21 54 50 < 50 < 50 < Good 3H 120% 93 79 22 32 50 < 50 < 50 < Good 3H 80% 92 72 23 28 50 < 50 < 50 < Good 3H 50% 90 68 23A* 120 5 8 20 Swelled in 2B 40% 96 75 parts 23B 72 18 30 50 < Entire surface F 25% 92 18 swelled 23C 12 50 < 50 < 50 < Swelled in parts 3H 60% 88 21 TABLE 6 (continued) NOTES: a. For the hardening property, the coated film surface was rubbed with a cloth dipped in methyl ethyl ketone, and the property was judged by the number of times rubbed until the coating film detached. b. For the coated surface stated under high humid ity, judgment was made after letting stand 1 day under an environment of 40 and 90% relative humdity after spraying. c. Pencil hardness was evaluated 1 week after coating. d. The coating film was detached by the mercury amalgam method one week. after coating, and the elongation. at breaking was measured with a tensile testing instrument. e. Weather resistance was judged by the gloss retention rate (%) after irradiating with a QW tester for 500 hours. PREPARATIONS 9-13 Toluene,89 parts by weight, and methyl isobutyl ketone,20 parts by weight, were introduced into a reactor which was equipped with a stirrer, a reflux cooling tube, a thermometer, and a dropping vessel; after heating to 850 C, a mixture consisting of the respective monomers and polymerization intitiators indicated by the respective numbers in Table 1 was dripped from the dropping vessel taking 4 hours, while stirring. The reaction solution was maintained at 85 to 900 C and, at the time of termination of the dripping, 0.3 weight parts of the polymerization initiator, azobisisobutyronitrile, was further added and by continuing the reaction at the abovementioned temperature for four hours, there was obtained a solution of an isocyanate-group-containing copolymer. The solids component content, viscosity, and quantity of isocyanate group contained (equivalent quantity/1000 g solution) of the copolymer solutions which were obtained in the respective preparation numbers are also given in Table 7: TABLE 7 PREPARATION 9 10 11 12 13 m-isopropenyl-a, a-dimethyl benzyl isocyanate 15 25 - - - p-isopropenyl-a,-dimethyl- benzyl isocyanate - - 15 - m-ethylenyl- a, a-dimethyl- benzyl isocyanate - - - 30 Isopropenyl-&alpha;, &alpha;, &alpha;', &alpha; ;' -tetra- methylxylylene diisocyanate - - - - 10 Methyl methacrylate 40 - 20 - 30 n-butyl methacrylate 20 - - - 10 Ethyl acrylate - 15 - 20 n-butyl acrylate- 25 20 40 20 40 Cyclohexyl methacrylate ¯ - ¯ 10 - Styrene - 20 - 20 p-methylstyrene - - 15 - Acrylonitrile - 20 10 - 10 Azobisisobutyronitrile 1 I I 1 1 Solid component content (weight %) 48.5 50.2 50.0 48.7 49.0 Viscosity (cps/250C) 1100 2200 1900 1700 900 Isocyanate content quantity (eg/1000 g) 0.37 0.62 0.37 0.80 0.35 EXAMPLES 24-33 As a general procedure, to 100 parts by weight of each of the copolymer solutions of Preparations 9 to 13 which were given in Table 7, were added titanium oxide 50 parts by weight, toluene 50 parts by weight, ethyl acetate 50 parts by weight, and a silicon system leveling agent 0.1 part by weight; dispersing was conducted for 1 hour with a sand mill and there was obtained a pigment dispersion of an isocyanate-group-containing copolymer in each case. Next, according to the compounding proportions shown in Table 8, the respective ketimine compound solutions given in Table 4 were mixed with 27 weight parts of the respective above-mentioned pigment dispersions, and the respective coating materials consisting of the compositions for covering of this invention were prepared. TABLE 8: ISOCYANATE-CONTAINING PREPOLYMERS AND KETIMINES PREPARATION NUMBER OF QUANTITY OF KETIMINE COMPOUND ISOCYANATE-GROUP-CON- SOLUTION COMPOUNDED TAINING POLYMER IN PIGMENT DISPERSION Preparation Preparation Preparation Preparation EXAMPLES 5 6 7 8 Nos. 24 Preparation 9 -- 1.0 -- -25 Preparation 9 -- -- 0.9 -26 Preparation 10 1.3 -- -- -27 Preparation 10 -- 1.6 -- -28 Preparation 10 -- -- 1.6 -29 Preparation 10 -- -- -- 1.4 30 Preparation 11 0.8 -- -- -31 Preparation 12 -- 1.8 -- -32 Preparation 13 -- 1.0 -- -33* Coating Material for -- -- -- 0.8 Comparison * Control. PREPARATION 33A* To 100 weight parts of a 50% toluene solution of a copolymer of methyl methacrylate, styrene, butyl acrylate, and 2-hydroxyethyl methacrylate (the hydroxyl group content quantity in the 50% solution was 0.62 equivalent per 1000 g, and the viscosity was 1500 cps/25 C), was added titanium oxide 50 parts by weight, toluene 50 parts by weight, ethyl acetate 50 parts by weight, ethylene glycol monoethyl ether acetate 20 parts by weight, and a silicone system leveling agent 0.1 part by weight; dispersing was conducted for 1 hour with a sand mill and there was obtained a pigment dispersion of an isocyanate-group-containing copolymer. To 27 parts by weight, of this pigment dispersion, was added 1.4 weight parts of a 75% ethyl acetate solution of a modified hexamethylene diisocyanate (trade name Desmodur N of the Bayer Company) and there was thus prepared a coating material for comparison. Each of the above-mentioned coating materials 24 to 33A was coated with a spray onto a 0.8 mm steel sheet so that the dried coating film would be about 30u thick, and drying was conducted at 250 C, 50% relative humidity. Also the usable time for each coating material was tested by sealing the coating material in a glass bottle and measuring the time until gelation at 250 C. The test results for the respective coating materials and coating films are given in Table 9: TABLE ): ISOCYANATE-CONTAINING PREPOLYMERS AND KETIMINES PROPERTIES: USABLE TIME HARDENING PROPERTY PENCIL FLEXIBILITY GLOSS WEATHER (GELLING TIME) HARDNESS ERICHSEN 60 C RESISTANCE GLOSS RE1 Days 2 Days 4 Days TENTION Later Later Later EXAMPLES HOURS mm % 24 48 50 < 50 < 50 < 2H 6.0 89 90 25 50 45 50 < 50 < 2H 4.5 91 92 26 24 50 < 50 < 50 < 3H 3.5 90 84 27 28 50 < 50 < 50 < 2H 5.8 92 83 28 30 50 < 50 < 50 < 2H 4.7 92 87 29 18 50 < 50 < 50 < 3H 3.0 93 80 30 36 50 < 50 < 50 < 2H 4.0 92 88 31 32 50 < 50 < 50 < 3H 5.2 94 85 32 60 40 50 < 50 < 2H 6.3 87 90 33 32 36 50 < 50 < 2H 4.8 89 83 33A* 9 12 20 40 2H 1.8 90 78 * Control ** See Footnote to Table 6 Many variations will suggest themselves to those skilled in this art in light of the above, detailed description. All such variations are within the full intended scope of the appended claims.

Claims: WHAT IS CLAIMED IS: 1. A moisture curable composition comprising (a) a low polymer containing isocyanate groups attached to aliphatic carbon atoms; (b) a ketimine reaction product of a di- or polyamine and a ketone. 2. A composition as defined in Claim 1 wherein component (a) comprises an adduct of a compound containing isocyanate groups attached to aliphatic carbon atoms with a stoichiometric insufficiency of water, an organic diol or an organic polyol, or a hydroxyl-containing polymer. 3. A composition as defined in Claim 2 wherein said hydroxyl-containing polymer comprises a polyester, a polyether, a polyacrylate, a polymethacrylate or a mixture of any of the foregoing. 4. A composition as defined in Claim 1 wherein component (a) is an adduct of a,a,a',a'-tetra- methyl-meta-xylylenediisocyanate. 5. A composition as defined in Claim 4 wherein component (a) is an adduct of a,a,a',a'-tetra- methyl-meta-xylenediisocyanate and l,l,l-trimethylolpropane,polytetramethylene ether glycol, a hydroxylcontaining polyacrylate,a polycaprolactone, or a mixture of any of the foregoing. 6. A composition as defined in Claim 1 wherein component (a) is a polyester polyurethane or a polyether polyurethane, each of which contain isocyanate groups attached to aliphatic carbon atoms. 7. A composition as defined in Claim 1 wherein component (a) comprises a copolymer which is obtained by copolymerizing from 2 to 50 percent by weight of a monomer of the formula: EMI40.1 wherein R is hydrogen or C1-C6 alkyl and n is an integer of 1 to 2, and 50 to 98 percent by weight of an ethylenically unsaturated compound which is copolymerizable with said monomer. 8. A composition as defined in Claim 1 wherein ketimine component (b) is derived from an aliphatic di- or polyamine and an aliphatic ketone. 9. A composition as defined in Claim 8 wherein ketimine component (b) is derived from ethylenediamine, 1, 6-hexanediamine, 114-bis(aminomethyl) cyclohexane, and acetone or methyl isobutyl ketone. 10. A composition as defined in Claim 8 wherein ketimine component (b) is substantially free of water of reaction 11. A composition as defined in Claim 1 which also includes: (c) a medium capable of dissolving components (a) and (b), said medium being non-reactive to isocyanate groups. 12. A method for coating a substrate, said method comprising: (1) providing a coating composition comprising: (a) a low polymer containing iso cyanate groups attached to ali phatic carbon atoms; (b) a ketimine reaction product of a di- orpolyamine and a ketone; and (c) a liquid medium capable of dissolving components (a) and (b), said medium being non reactive to isocyanate groups; (2) casting a film of said composition on the substrate to be coated and removing the liquid medium there from; and (3) providing sufficient time and moisture to effect cure of the compo sition into a hard, tough, solvent resistant surface coating.

Inventors: ARENDT, VOLKER DIETRICH
Applicants: AMERICAN CYANAMID COMPANY
Application year: 1984
Main classification: C08G18
IPC codes: C09D175, C08G18