MXPA97009952A - Aminoresin functionalized with carbamate groups and coating compositions that contains them - Google Patents

Abstract

The present invention relates to a crosslinking agent comprising one or more carbamate groups, or groups convertible to carbamate, and two or more polyfunctional amino moieties having the formula, wherein L is selected from the group consisting of alkyl or aryl, cycloalkyl and alkylaryl, with a carbon chain length between 1 and 6 carbon atoms, and N is a polyfunctional amino moiety. L may also have additional linking groups, such as deesters, ethers, ureas or urethanes groups. Also included is a method of preparing the crosslinking agent, a coating composition containing the crosslinking agent, and a method of coating the substrate with the composition.

Description

AMINORESIN FUNCTIONALIZED WITH CARBAMATE GROUPS AND COATING COMPOSITIONS THAT CONTAIN THEM Field of the Invention The present invention relates to crosslinking agents with carbamate functionality and coating compositions containing these crosslinking agents, particularly with clearcoat or topcoat coating compositions, having crosslinking agents with carbamate functionality in them. base to polyfunctional amino compounds.

BACKGROUND OF THE INVENTION Coatings are often applied in multiple layers, which may include, for example, one or more primer layers and one or more top coats. The final layers can be used to provide color and other aesthetic properties. The final layers are often applied either as a layer, as a color layer, for example, the well-known acrylic enamels, or in two layers, as a color layer, with a transparent overcoat. Colored composite coatings plus transparent coatings are widely used, particularly in the automotive industry, due to their exceptional appearance. The requirements for automotive coatings are particularly strict. Automotive coatings should not only have the desirable appearance properties of high gloss, vividness of color, sharpness of the image, etc. The final layers must also be resistant to wear, scratching, degradation or staining of environmental depositions, powder decomposition, and other forms of film degradation. In a coating of colored composite plus transparent layer, it is particularly critical to have a transparent layer that is resistant to the degradation of the film. Rehfuss et al. in Pat. US Nos. 5,356,669 and 5,474,811, the disclosure of which is incorporated herein by reference, disclose clearcoat compositions comprising polymers with carbamate functionality, which can be cured by reaction with compounds having a plurality of groups reactive with carbamate Reactive diluents with carbamate functionality are described in WO 87/00851, Hoy et al .; Pat. No. 5,115,015, US, Richey, Jr., et al .; Pat. No. 4,814,382, from the USA, Hoy et al .; Pat. No. 4,677,168, from the USA, Hoy et al .; and Pat. No. 4,520,167, US, Blank et al., The disclosures of which are incorporated herein by reference. Reactive diluents with carbamate functionality are compounds with low molecular weight with a carbamate group. Due to their manofunctionality, said compounds can not be used as crosslinking agents in coating compositions. The crosslinking agents with dicarbamate functionality, based on carbamate functional polymers, are disclosed in Pat. No. 5,373,069 to U.S. Rehfuss, the disclosure of which is incorporated herein by reference. Tricarbamate functional crosslinking agents, based on isocyanurate-type materials, are disclosed in US Pat. No. 5,336,566 of EE. EE., Of Rehfuss, the disclosure of which is incorporated herein by reference. These materials have a cyanuric ring core and three primary carbamate terminal groups. The crosslinking agents of alkoxycarbonylamino-1, 3, 5-triazine are disclosed in Pat. No. 4,939,213, US; Pat. No. 5,084,541, US; Pat. No. 5,288,865, from the USA; WO 96/15185, Kuang et al .; WO 96/04258, Flood et al .; WO 96/11915, Bay; and EP 0 624 577, Flood et al., the disclosures of which are incorporated herein by reference. The crosslinking agent described in these references has secondary carbamate groups on the amino group that reacts with alcohols or other materials containing active hydrogen. It is thought that the mechanism of the reaction includes loss of alcohol from the carbamate crosslinking agent and then the formation of a urethane linkage with the active hydrogen-containing material. It has now been discovered that carbamate functionality crosslinking agents can be synthesized based on polyfunctional amino compounds. The compositions of the present invention include crosslinking agents with primary or secondary carbamate functionality, based on polyfunctional amino compounds, in combination with binding resins, such as addition polymers, or resins to inoplastic and materials having at least two groups with carbamate-reactive functionality. The coatings formed by the compositions of the present invention have crosslinked networks with urethane bonds. It has been shown that these bonds are durable and resistant to environmental degradation, according to Rehfuss et al. comment and reveal in Pat. Nos. 5,356,669 and 5,474,811, from the USA.

SUMMARY OF THE INVENTION According to the present invention, there is provided a carbamate functional crosslinking agent based on polyfunctional amino compounds and a curable coating composition comprising the crosslinking agent with carbamate functionality. The crosslinking agent comprises one or more carbamate groups or groups convertible to carbamate and one or more polyfunctional amino moieties, and has the formula O I ?? - -L-O-C-NHR where L is alkyl, aryl, cycloalkyl or alkylaryl, with a carbon chain length between 1 and 6 carbon atoms. L may also have additional linking groups, such as groups of esters, ethers, ureas or urethanes. R is hydrogen, alkyl or cycloalkyl with a carbon chain length between 1 and 6 carbon atoms, and N is a polyfunctional amino moiety. The polyfunctional amino moiety may be primary or secondary amine, alkylala, or alkoxyamine groups. It is thought that coatings using current crosslinking agents with primary carbamate functionality, based on aminoresins, offer an advantage over crosslinking agents, such as those disclosed in WO 96/15185, because in the latter, the proximity of the triazine ring activates a cured bond formed with the main resin, making degradation of the crosslinking linkage more likely.

Detailed Description Carbamate functional crosslinking agents comprising a polyfunctional amino moiety, according to the invention, can be formed from any amino or aminoplast moiety or any mixture thereof, having, on average, per molecule, more than an amine group, alkoxylated amine group, or any mixture of these groups. Aminoplasts are well known as a class of materials, and there are many aminoplasts that can be obtained commercially, for example, from Cytec Industries, Inc., West Paterson, NJ, under the trade names of CYMEL® and BEETLE®, or from Monsanto Corporation , under the trade name RESIMENE®. The amino portion may comprise ureas, thioureas, melamines, benzoguanamines, dihydroxyethyleneureas, acetoguanas inas, alkoxynitriles, cyclohexylcarboguanamines, N, N'-dimethyl ureas, acetylenediureas, amides, dicyandiamides, guanilureas, glycolurils, and the like, the products of these materials with aldehydes, such as formaldehydes, and condensates of these. Other triazines, triazoles, diazines, guanidines, substituted ureas or guanamines can also be used. As mentioned, the amino portion can be converted partially or wholly to alkylol groups, by reaction with an aldehyde. Usually formaldehyde is used, but other aldehydes, such as acetaldehyde, paraformaldehyde, trioxane, crotonaldehyde and benzaldehyde are also useful. The amine formaldehyde resin is manufactured in a known manner, by acid catalyzed condensation, preferably using aqueous formaldehyde. In a preferred embodiment, the modified amino-triazine-aldehyde resin is used, such as those described in US Patent No. 3,082,180, the disclosure of which is incorporated herein by reference. It is also possible to partially or substantially completely etherify the alkylol groups, using one or more monofunctional alcohols, for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tert-butanol or benzyl alcohol. A preferred group of amino compounds is that of fully methylolated and substantially completely methylolated melamines, which may, for example, be manufactured in accordance with the process disclosed in Pat. No. 4,293,692, US, the disclosure of which is incorporated herein by reference. Another useful type of amino compound is the fully mixed, alkylated and substantially completely methylolated glycoluril derivatives, such as dimethoxymethyl diethoxymethyl glycoluril, as described in US Pat. No. 4, 105,708, US, the disclosure of which is incorporated herein by reference. Aminoresin can also be the product of the reaction of a hydrogen on the amino group, with an epoxy, or the exchange product of a functionalized amine, such as 5-aminohexanol with melamine. It is especially preferred that the amino portion be melamine, urea, compounds containing urea, melamine-formaldehyde and glycoluril-formaldehyde. The mela-ina-formaldehyde and the glycoluril-formaldehyde can be partially or substantially completely alkylated and methylolated. Therefore, the preferred compounds may have unmodified amino groups, methylol groups, ether groups, and any combination of mixtures of these groups. Particularly preferred examples are melamine, hexamethylolmelamine, pentamethylolmelamine, tetramethylolmelamine, trimethylolmelamine, dimethylolmelamine and monomethylolmelamine.; and partially or substantially completely alkylated derivatives thereof, such as hexametoxymethylmelamine. The carbamate groups can be generalized by the structure -0-C (= 0) -NHR. Carbamate functional crosslinking agents based on polyfunctional amino compounds are formed by reacting the aminoplast or amino moiety with a compound having one or more carbamate groups or with a compound having one or more groups that can be converted to groups of carbamate Groups which can be converted to carbamate groups include cyclic carbonate groups, epoxy groups and unsaturated bonds. The cyclic carbonate groups can be converted to carbamate groups by reaction with ammonia or primary amine, to form a β-hydroxycarbamate. The epoxy groups can be converted to a cyclic carbonate by reaction with CO 2, followed by conversion to the β-hydroxycarbamate. The conversion of the oxirane group to a cyclic carbonate can be done at any pressure, from atmospheric pressure to supercritical pressures of C02, preferably from about 60 to about 150 pounds / inch2 (4.22-10.55 kg / cm2), and at temperatures of approximately 60BC to approximately 150SC. Useful catalysts include any that activates an oxirane ring, such as salts of quaternary amine or tertiary amine, for example, tetraethylammonium bromide; combinations of alkylphosphonium halides and complex organotin halides, for example, tetramethyltinium iodide, tetrabutyltiniumiodide, tetrabutylphosphonium iodide and tetramethylphosphonium iodide; potassium salts, for example, potassium carbonate and potassium iodide, preferably in combination with crown ethers; tin octoate, calcium octoate and the like. The unsaturated bonds can be converted to carbamate groups by reaction with peroxide, to generate an epoxy group, then, conversion of the epoxy group to a carbonate group, and finally, conversion to the carbamate group, according to the procedures described above. The carbamate is primary or secondary, ending in a group NR, where R is H, alkyl or cycloalkyl, with between 1 and 6 carbon atoms and can be substituted or unsubstituted. In a useful synthesis of the carbamate functional compounds of the invention, a methylol group of aminoresin can be reacted with urea or cyanic acid at elevated temperature, preferably also with a catalyst, to form a primary carbamate group. A carbamate group can also be formed by the reaction of an alcohol with phosgene, and then with ammonia or amine, to form a carbamate group. An alkoxylated amino compound can be reacted with a hydroxyalkyl carbamate. Still another approach is to react a semi-dried isocyanate with a hydroxycarbamate, such as a hydroxypropyl carbamate, with a group of alcohol in the amino-resin. A third technique is the esterification of an alcohol with an alkylcarbamate. For the transesterification, the carbamate compounds with lower alkyl groups are preferred. The esterification can be catalyzed by titanate, tin or Lewis acids catalysts. Examples of useful catalysts include, without limitation, dibutyltin dilaurate, dibutyltin oxide, and isobutoxy titanate. The reaction can also be catalyzed by Brónsted acids, such as para-toluenesulfonic acid. By another method, an alkoxylated aminoresin can be reacted with glycerin carbonate. Then, the carbonate ring can be opened with ammonia or amine, to form the beta-hydroxycarbamate. Alternatively, the carbonate ring can be opened with a primary or secondary amine, and then converted to a carbamate group by any of the methods described herein. By another method, an exchange reaction is performed between amino groups of aminoresin and an amine containing a functional group, which can be converted to a carbamate group. Then, the functional group is converted to a carbamate group. A non-limiting example of this is the exchange reaction of melamine with an aminoalcohol, such as 1-aminohexanol, followed by reaction with phosgene, then ammonia or amine.jan.

Finally, the carbamates can be prepared by transcarbamylation of an alcohol with an alkylcarbamate, for example, methyl carbamate, ethyl carbamate or butyl carbamate, to form a carbamate group in aminoresin. The transcarbamylation is preferably carried out at an elevated temperature, and preferably in the presence of a catalyst, such as an organometallic catalyst, for example, dibutyltin dilaurate. Another class of useful compounds, such as the carbamate functional crosslinking agent, includes the polycarbamate resins and alkoxylated polycarbamate resins, which can be obtained under the tradename PLASTOPAL®, from BASF Corporation, Mt. Olive, NJ. In particular, preferred compounds include the dicarbamates, alkylated or alkoxylated dicarbamates, or dicarbamates with mixtures of these groups. The preferred compounds are of the formulas R \ 'N-C (= O) -0R5O-C (= O) N, R2 R4 where R :, R2, R3 and R4 are each independently selected from the group consisting of H, R5OH and R6OR7, where R6 is an alkyl group of up to 6 carbon atoms and R7 is alkyl of up to 6 carbon atoms; and, further, where R5 is alkyl of up to 20 carbon atoms. In a preferred embodiment, the alkoxylated polycarbamate resin is selected from those which are etherified with isobutanol, n-butanol or methanol. Examples of suitable resin or compounds include, without limitation, Plastopal BTB, Plastopal BTA, Plastopal BTM and Plastopal RL 8822, all commercially available from BASF Corporation, Mt. Olive, NJ. If a polycarbamate is used, the amino groups can be converted partially or wholly to alkylol groups, by reaction with an aldehyde. Usually formaldehyde is used, but other aldehydes, such as acetaldehyde, paraformaldehyde, trioxane, crotonaldehyde and benzaldehyde, are also useful. The amine-aldehyde resin is manufactured in a known manner, by acid catalyzed condensation, preferably using an aqueous formaldehyde. It is also possible to partially or substantially completely etherify the alkylol groups using one or more monofunctional alcohols, for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tertiary butanol or benzyl alcohol. A preferred group of aminoresins is that of fully methylolated and substantially completely methylated polycarbamate resins. Another useful type of aminoresin is that of fully mixed, alkylated and substantially completely methylolated polycarbamate resins. The carbamate functional compound is combined in the coating composition of the invention with an aminoplast resin, aminoplast material, or an amino polymer having more than one reactive group with carbamate functionality. The resin, material or polymer having more than one reactive group with carbamate functionality can be any resin of the type known to be useful in coating compositions. Preferably, especially for automotive coatings, at least one resin from the group of polyesters, polyurethanes, addition polymers, polyester-polyurethane graft copolymers, aminoplasts and mixtures thereof is used. Particularly it is preferred to use addition polymers having one or more groups with reactive functionality with primary carbamate. Such addition polymers include, without limitation, acrylic polymers, vinyl polymers, such as copolymers of vinyl esters, and the like. Of these, acrylic polymers and blends including acrylic polymers are particularly preferred as the resin with at least two groups with reactive functionality with primary carbamate. Alternatively, aminoplast resins could be used, where the melamine resins are the preferred aminoplast. The carbamate reactive groups are preferably isocyanate, anhydride, siloxane or alkoxylated amino groups. These materials can be cured by themselves, or in combination with other crosslinking portions. These other crosslinking portions may or may not be reactable with the carbamate or crosslinking species composed of carbamate. They could be in separate materials or covalently bound to one or more parts of the amino crosslinking agent with carbamate functionality and / or the group reactable with the amino crosslinking agent with carbamate functionality. A non-limiting example of this is the addition of an epoxy-functional resin with an acid-functional resin. Another non-limiting example is the addition of the crosslinking agent alkoxycarbonylamino-1, 3, 5-triazine, disclosed in Pat. No. 4,939,213 from the USA UU and an acrylic resin with hydroxyl functionality. When the carbamate reactive material is an addition polymer, with at least two carbamate reactive functional groups, the preferred addition polymers can be formed by including monomers, such as, without limitation, alkoxylated acrylamides and alkoxylated methacrylamides, such as such as N-butoxymethacrylamide, N-methoxymethyl ether, and N-isobutoxymethacrylamide; alkylacrylamidoglycolate and alkyl ethers, and etherified or esterified related methacrylamide or acrylamide derivatives, including methyl methacrylamidoglycolate methyl ether (sold under the tradename MAGME by Cytec Industries, Stamford, CT) and butylacrylamidoglycolate methyl ether; alkoxylated methacrylates and ureaacrylates, such as hydroxyethylethyleneurea methacrylate (HEEU esterified with methacrylic acid, which can be obtained commercially as Norsocryl 100 from Elf Atochem), followed by reaction with an aldehyde; isocyanate-functional monomers, such as meta-isopropenyl-α, α-dimethylbenzyl isocyanate (which can be obtained commercially under the trade name TMI®, from Cytec Industries, Stamford, CT), isocyanate-functional ethyl methacrylate (which it can be obtained commercially from Dow Corp., Midland, MI); monomers with anhydride functionality, such as maleic anhydride; and siloxane monomers or polysiloxane macromonomers, such as those commercially available from Huís. Examples of alkoxylated amides include, without limitation, such compounds as N- (1, 1-dimethyl-3-oxobutyl) -acrylamide, N-alkoxyamides, such as methylolamides; N-alkoxy acrylamides, such as n-butoxy acrylamide; N-aminoalkylacrylamides or methacrylamides, such as aminomethylacrylamide, l-aminoethyl-2-acrylamide, 1-aminoethyl-2-acrylamide, l-aminopropyl-2-acrylamide, 1-aminopropyl-2-methacrylamide, Nl- (N-butylamino) propyl - (3) -acylamide and 1-aminohexyl- (6) -acylamide and 1- (N, N-dimethylamino) -ethyl- (2) -methacrylamide, 1- (N, N, dimethylamino) -propyl- (3) -acylamide and 1- (N, N-dimethylamino) -hexyl- (6) -methacrylamide. Acrylic copolymers containing MAGME are described by Howard R. Lucas in Effect of a-Methyl Groups on Room Tempera ture Crosslinking in Acrylic Polymers Containing MAGME Monomers (Effects of a-Methyl Groups on Crosslinking to Ambient Tempera ture in Acrylic Polymers They contain MAGME Monomers), Journal of Coa tings Technolgy, Vol. 57, No. 731, 49 (December 1985), the disclosure of which and cited references are incorporated herein by reference. Polymers of N- (alkoxymethyl) acrylamides are described in many references, including those by Christenson, et al., USA. UU 3,079,434; Trucker, USA UU 3,326,868; Flegenheimer, USA UU 3,344,097; and Christenson et al., USA. UU 3,247,139, each of which is incorporated herein by reference. The unsaturated monomer, with a group with functionality reactive with the carbamate, can be polymerized together with one or more unsaturated copolymerizable monomers, known in the art. Such copolymerizable monomers include, without limitation, α, β-ethylenically unsaturated monocarboxylic acids containing from 3 to 5 carbon atoms and the esters or nitriles of these acids; unsaturated α, β-ethylenically dicarboxylic acids containing from 4 to 6 carbon atoms and the anhydrides, monoesters and diesters of these acids; vinyl esters, vinyl ethers, vinyl ketones and heterocyclic or aromatic aliphatic vinyl compounds. Representative examples of useful esters of acrylic, methacrylic or crotonic acids include, without limitation, such compounds as alkyl esters and substituted alkyl esters of said acids, particularly those of reaction with saturated cycloaliphatic and aliphatic alcohols, containing from 1 to 20 carbon atoms, such as methacrylates and acrylates of methylol, ethyl, propyl, isopropyl, n-butyl, isobutyl, tertiary butyl, 2-ethylhexyl, lauryl, stearyl, cyclohexyl, trimethylcyclohexyl, tetrahydrofurfuryl, sulfoethyl and isobornyl; and polyalkylene glycol methacrylates and acrylates. Representative examples of other monomers polymerizable with unsaturated ethylene include, without limitation, compounds such as esters, semi esters, fumaric, maleic, and itaconic anhydrides. Representative examples of polymerizable vinyl monomers include, without limitation, such compounds as vinyl acetate, vinyl propionate, vinyl ethers such as vinyl ethyl ether, vinyl and vinylidene halides, and vinyl ethyl ketone. Representative examples of heterocyclic or aromatic aliphatic vinyl compounds include, without limitation, compounds such as styrene, α-methylstyrene, vinyltoluene, t-butylstyrene and 2-vinylpyrrolidone. Other suitable copolymerizable monomers include α-olefin compounds, such as ethylene, propylene; diene compounds, such as butadiene and isoprene; and compounds with silicon or fluorine atoms, such as 1H, 1H, 5H-octafluoropentyl acrylate and trimethylsiloxyethyl acrylate. The addition copolymers are preferably acrylic polymers. For purposes of this invention, acrylic polymers are defined as polymers that include one or more α-β-ethylenically unsaturated monocarboxylic acids, containing from 3 to 5 carbon atoms or derivatives of these acids, such as the esters mentioned above. Preferred acrylic polymers can be prepared using conventional techniques, such as free radical polymerization, cationic polymerization or anionic polymerization, in, for example, a batch or semi-batch process. For example, the polymerization can be carried out by heating the monomers with unsaturated ethylene, in bulk or in organic solution or aqueous dispersion in the presence of a free radical source, such as an organic peroxide or azo compound and, optionally, an chain transfer for a batch process; or, alternatively, the monomers, initiator (s), and any chain transfer agent can be fed at a controlled rate in a heated reactor, charged with solvent in a semi-batch process. Typical sources of free radicals are organic peroxides, including dialkyl peroxides, such as di-tert-butyl peroxide and dicumyl peroxide, peroxyesters, such as tertiary butyl peroxy-2-ethylhexanoate and tertiary butyl peroxypivalate; peroxydicarbonates, such as di-2-ethylhexylperoxydicarbonate and dicyclohexylperoxydicarbonate; diacyl peroxides, such as dibenzoyl peroxide and dilauroyl peroxide; hydroperoxides, such as eumeno hydroperoxide and tertiary butyl hydroperoxide; ketone peroxides, such as cyclohexanone peroxide and methyl isobutyl ketone peroxide; and peroxyketals, such as 1,1-bis- (t-butylperoxy) -3,5,5-trimethylcyclohexane and 1,1-bis- (t-butylperoxy) -cyclohexane; as well as azo compounds such as 2,2'-azobis (2-methylbutanonitrile) and 1,1''-azobis (cyclohexanecarbonitrile). Typical chain transfer agents include mercaptans, such as octyl mercaptan, n- or tert-dodecyl mercaptan, thiosalicylic acid, mercaptoacetic acid and mercaptoethanol; halogenated compounds; and dimeric alpha-methylstyrene. Free radical polymerization is usually carried out at temperatures from about 20a to about 200aC, preferably from 90C to 170BC. The reaction can be conveniently carried out at reflux, although reflux is not required. When the resin having at least two groups with carbamate reactive functionality is an acrylic polymer, the polymer will generally have an average molecular weight, by number, of from about 1000 to about 40,000, preferably from about 1000 to about 6000, and still more. preferably from about 1000 to about 3000. The molecular weight can be determined by gel permeation chromatography using a polystyrene standard. The equivalent weight will generally be between approximately 200 and 1500, and more preferably will fall between about 300 and 340. The glass transition temperature can be adjusted according to methods well known in the trade, by means of selection and distribution of the comonomers. In a preferred embodiment, the T (J) of the acrylic having reactive functionality with carbamate could be between 20 ° C and 80 ° C, more preferably between about 20 ° C and 60 ° C. It is also possible, and in some cases it could be preferred, to form the resin that has at least two groups with carbamate reactive functionality, by adduction of a resin or preformed polymer, with a compound having carbamate-reactive functionality, eg, a compound having at least one isocyanate group can be used, anhydride group, alkoxylated amino group or siloxane group, together with at least one group reactive with functionality in the polymer or resin In a preferred synthesis of the polymer or resin having at least two groups with carbamate reactive functionality, an acid functional polymer or resin is reacted with hydroxyethyl ethyleneurea, which is then reacted with an aldehyde. skilled artisans, other combinations of adduction compound and resin or functional polymer that will result in polymer or resin having at least two groups with reactive functionality with primary carbamate. The coating compositions of the invention include at least one of the carbamate functional crosslinking agent of the invention, and at least one polymer or resin having at least two groups with carbamate reactive functionality. The carbamate functionality crosslinking agent can be included in an amount of from about 10 percent, by weight, to about 90 percent, by weight, preferably from about 20 percent, by weight, to about 80 percent , by weight, based on the total weight of the composition, excluding solvents. In a particularly preferred embodiment, the carbamate functional crosslinking agent is included in an amount of between about 30 percent, by weight, to about 70 percent, by weight, based on the total weight of the composition, excluding solvents . The polymer or resin having at least two groups with primary carbamate reactive functionality can be included in an amount of between about 10 percent, by weight, to about 90 percent, by weight, preferably between about 20 percent , by weight, to approximately 80 percent, by weight, based on the total weight of the composition, excluding solvents. In a particularly preferred embodiment, the polymer or resin having at least two groups with primary carbamate reactive functionality is included in an amount of from about 30 percent, by weight, to about 70 percent, by weight, based on the total weight of the composition, excluding solvents. The compositions may include one or more catalysts, and preferably include at least one catalyst for the crosslinking reaction. Useful catalysts include, without limitation, alkylsulfonic acid, arylsulfonic acids, and alkylarylsulfonic acids, such as methanesulfonic acid, p-toluenesulfonic acid, and dodecylbenzenesulfonic acid; dinonylnaphthalenedisulfonic acids; phosphoric acid and its esters, such as phenyl acid phosphate, hydroxyphosphate ester and butyl phosphate; Lewis acids, such as boron trifluoride etherate, trimellitic acid, monobutyl maleate, triflic acid; etc. When a catalyst is included, the catalyst is used at levels of between about 0.01 percent, by weight, about 2.0 percent, by weight, preferably between about 0.05 percent, by weight at about 1.0, percent, by weight, in based on the total weight of the coating composition. Although the coating compositions of the present invention can be used as powder coatings, in a preferred embodiment, the coating compositions additionally include organic solvents or water. In a highly preferred embodiment, the compositions are solvent based coating compositions. The organic solvent may be present in an amount of between about 5 percent, about 99 percent, by weight, preferably between about (20 percent to about 80 percent, by weight, and more preferably between about 20 percent, by weight. percent to about 50 percent, by weight, of the coating composition The selection of particular solvents can be made according to methods well known in the trade.The optimum solvent or optimum solvent mixture can be reached by simple tests In general, useful solvents include, but are not limited to, esters, particularly acetates, propionates and butyrates, alcohols, ketones, aromatic solvents, glycol ethers and glycol esters.Non-limiting examples of useful solvents include methyl ethyl ketone, methyl isobutyl ketone, amyl acetate, butyl acetate, butyl ether of ethylene glycol, methyl acetate ether of propylene glycol, xylene, toluene, isopropanol, butanol, naphtha and other mixtures of aromatic hydrocarbons, N-methylpyrrolidone, butyl acetate and isobutyl isobutyrate. The particular type (s) of solvent used and the optimum levels depend on the specific crosslinking agent and binder of the coating composition. The selection and distribution of the solvents can be done by simple tests. The compositions, according to the invention, can also be water-based compositions. In water-based compositions, water may be included in an amount between about 20 percent, by weight, to about 95 percent, by weight, preferably between about 30 percent, by weight, to about 70 percent. percent, by weight, of the coating composition. Water-based compositions preferably also include one or more organic co-solvents, such as butyl "Cellosolve", "Cellosolve" acetate or Texanol, at levels between about 1 percent, by weight, to about 20 percent, by weight, preferably between about 5 percent, by weight, to about 10 percent, by weight, based on the total weight of the coating composition. Any of the usual additives may be included in the coating compositions of the invention, including, without limitation, surfactants, fillers, stabilizers, wetting agents, dispersing agents, adhesion promoters, ultraviolet light absorbers, antioxidants, light stabilizers, clogged amine, additives for rheology control, such as thixotropes, leveling agents, slip agents, waxes, reactive diluents, additives to prevent cratering, etc. The amounts and combinations of said additives can be determined according to the usual methods employed in the guild. The composition may include additional cross-linking technologies, which may react or not with carbamate or with groups with reactive functionality with carbamate. These additional crosslinking technologies can be separated or covalently linked with one or more parts of the amino crosslinking agent with carbamate functionality and / or the group that can react with the amino crosslinking agent with carbamate functionality. A non-limiting example of this is the addition of an epoxy-functional resin with an acid-functional resin. Another non-limiting example is the addition of the alkoxycarbonylamino-1 crosslinking agent, 3, 5-triazine disclosed in a Pat. from USA UU The carbamate functional crosslinking agent is cured with a mixture of aminoplast based on melamine, such as monomeric hexametoxymethylmelamine and an acrylic resin of isobutoxymethylacrylamide. The coating compositions of the invention can be applied according to customary techniques, such as, for example, spray coating, even electrostatic coating methods, dip coating, roller coating, curtain coating, etc. For automotive body panels, spray coating methods are preferred. The coating compositions of the invention can be applied to many different types of substrates, including, without limitation, metal, plastic, ceramic, paper, leather, wood and wood-like substrates. Preferably, the compositions of the invention are applied on a primer layer. When the coating compositions, according to the invention, are used as a pigmented final layer, the pigment can be any organic or inorganic pigment or dye; filling; metallic pigment or other flake pigment; or combinations of these. The flake pigment can be, for example, aluminum or mica flakes. The pigments are usually used in final coat compositions at pigment to binder ratio levels between about 0.1 to about 1.0. In a preferred embodiment, the composition of the invention can be used as the transparent layer on a pigmented base layer, as part of a colored composite coating plus transparent layer. The pigmented base coat is preferably applied over a primer layer. The pigmented base coat compositions for said composite coatings are well known in the trade and are described in detail in many patents and elsewhere. The polymers known in the art to be useful in basecoat compositions include acrylics, vinyls, polyurethanes, polycarbonates, polyesters, alkyds and polysiloxanes. Preferred polymers include acrylics and polyurethanes. The basecoat compositions are preferably thermosetting compositions that are cured to a crosslinked insoluble coating layer. Preferred are the "wet" basecoat / clearcoat systems, in which the clearcoat composition is applied to the basecoat composition before the latter is cured. After the article is coated with at least the composition of the invention having an amino-carbamate-based crosslinking agent, the coated article can be subjected to conditions for curing the coating layer or layers. Although various methods of curing may be possible, heat curing is the usual and preferred method. Generally, heat curing can be effected by exposing the coated article at elevated temperatures provided, for example, by heat sources by radiation. The curing temperature is preferably between about 180 SF to about 310 aF, and more preferably between about 250aF to about 285aF. The article can be cured for a period of time between about 15 to about 45 minutes, preferably between about 20 to about 30 minutes. The invention is further described in the following examples. The examples are merely illustrative and in no way limit the scope of the invention, as described and claimed. All parts are parts by weight, unless specifically indicated otherwise.

Examples Example 1. Crosslinking Agent with Carbamate Functionality, Based on Hexamethoxymethylmelamine. A. Preparation of Melamine with Oxydryl Functionality A mixture of 914 parts, by weight, of CYMEL® 303 (available from Cytec Industries, Stamford, CT), 826.8 parts of hydroxypropyl carbamate and 1000 parts of methanol was heated to 69 ° C. under an inert atmosphere. A total of 12 parts of dodecylbenzenesulfonic acid was added to the mixture. The reaction mixture was maintained at less than 70 BC until all of the hydroxypropyl carbamate had been incorporated into the melamine. At that point, 379.5 parts of methyl carbamate were added to the mixture. The mixture was heated to reflux, and the reflux was maintained until again, the methyl carbamate was no longer being incorporated.

After the addition of 3.5 parts of AMP-95 aminomethylpropanol, 95% (commercially available from Angus Chemical Corp., Buffalo Grove, IL), the reaction mixture was distilled by aspiration, to remove the unreacted methyl carbamate. . After the distillation by aspiration, 882 parts, by weight, of amyl acetate were added. The resulting resin solution had an equivalent, by weight, of hydroxyl, of 348 g./equiv. in solution. B. Preparation of Melamine with Carbamate Functionality A mixture of 68 parts, by weight, of isophorone diisocyanate, 73.6 parts, by weight, of methyl isoamyl ketone, and 0.2 parts, by weight, of dibutyltin dilaurate was prepared, and 36.5 parts, by weight, of hydroxypropyl carbamate were slowly added to the mixture. During the addition, the reaction temperature was not allowed to be higher than 39 BC. After it was determined that the hydroxypropyl carbamate had been incorporated by NCO titration with dibutylamine, 110.5 parts, by weight, of the hydroxypropyl melamine of Part A were added. The reaction mixture was heated to 65 ° C. until all of the isocyanate was consumed, as determined by titration, with dibutylamine. The reaction mixture was cooled and then 28 parts, by weight, of n-butanol were added. C. Curing of the Crosslinking Agent with Carbamate Functionality, Based on Hexamethoxymethylmelamine A mixture of 52.8 parts, by weight, of the melamine product with carbamate functionality of Part B, 3.9 parts, by weight, of hexametoxymethylmelamine, and 0.3 parts , by weight, of dodecylbenzenesulfonic acid was applied on glass, with a thickness of 8 millimeters. The application was baked in an oven, at 285 SF (140.5), for 30 minutes. The cured coating layer was hard and transparent. The cured coating layer was soaked for one minute with methyl ethyl ketone, without any observable effect. A test of the cured coating layer was also made, with 200 double rubs with methyl ethyl ketone, without any observable effect.

Example 2. Crosslinking Agent with Carbamate Functionality, Based on Hexamethoxymethylmelamine A. Preparation of Melamine with Functionality of Carbamate In a suitable reactor, a mixture of 400 parts, by weight, of monomeric hexametoxymethylmelamine, 318 parts of hydroxypropyl carbamate, 300 parts , by weight, of butyl carbamate, and a catalytic amount of zinc nitrate, was slowly heated to 60 ° C under an inert atmosphere. Aspiration was applied to the reaction mixture, to remove the reaction byproduct of methanol. When the reaction mixture reached 100 BC, the temperature was maintained at about 100 BC, until the calculated weight of methanol was removed. At this point, 500 parts, by weight, of toluene, 260 parts, by weight, of methyl carbamate, and a catalytic amount of dibutyltin oxide were added to the reactor. The reaction mixture was heated to reflux. The by-product of the transcarbamation reaction, methanol, was removed. The progress of the reaction was monitored by titration of the hydroxyl functionality. When the concentration of hydroxyl had decreased to less than 10% of its initial level, the batch was distilled by aspiration of solvent and unreacted materials. The resin viscosity of the product was adjusted with the addition of 104 parts, by weight, of Dowanol® PM (available from Dow Corp., Midland, MI). B. Curing of Carbamate Functional Crosslinking Agent, Based on Hexamethoxymethylmelamine A mixture of 120 parts, by weight, of the melamine product with carbamate functionality, of Part A, 14.5 parts, by weight, of hexametoxymethylmelamine, 35 parts, by weight, of Dowanol * 'PM, and 1.0 part, by weight, of dodecylbenzenesulfonic acid blocked with oxazolidinone was applied on glass, with a thickness of 8 millimeters. The application was baked in an oven, at 275 ° F (135.0ßC), for 25 minutes. The cured coating layer is hard and transparent. The cured coating layer was soaked for one minute in methyl ethyl ketone, without any observable effect. A test of the cured coating layer was also made, with 200 double rubs with methyl ethyl ketone, without any observable effect.

Example 3. Coating Composition Containing Carbamate Functional Crosslinking Agent, Based on Hexamethoxymethylmelamine A. Preparation of N-Isobutoxymethacrylamide Polymer In an appropriate vessel, equipped with a condenser, 1125 parts, by weight, of isobutyl alcohol were heated, to reflux in nitrogen. Once the reflux was reached, the nitrogen was stopped, and a mixture of 988 parts of N-isobutoxymethacrylamide, 748 parts of styrene, 747 parts of 2-ethylhexyl acrylate, 248 parts of VAZO-67 (obtainable from DuPont de Nemours, Inc.) and 115 parts of isobutanol, over a period of two hours. All parts are by weight. After the addition was complete, 200 parts of isobutanol were added. Reflux was maintained for an additional 30 minutes. B. Preparation of the Coating Composition A mixture of 35.6 parts, by weight, of the melamine with carbamate functionality of Example 1, Part B, 27.2 parts, by weight, of the N-isobutoxymethacrylamide polymer of Example 3, Part was formed. A, and 0.19 parts, by weight, of dodecylbenzenesulfonic acid. The mixture was applied on glass, with a thickness of 8 millimeters. The application was baked in an oven, at 285aF (140.5aC), for 30 minutes. The cured coating layer was hard and transparent. The cured coating layer was soaked for one minute in methyl ethyl ketone, without any observable effect. A test of the cured coating layer was also made, with 200 double rubs with methyl ethyl ketone, without any observable effect. The invention has been described in detail, in relation to preferred embodiments thereof. However, it should be understood that variations and modifications can be made within the spirit and scope of the invention.

Claims (22)

Claims
1. l. A crosslinking agent comprising one or more carbamate groups, or groups convertible to carbamate, and two or more polyfunctional amino moieties having the formula Or I II -N-L-O-c-NHR, wherein L is selected from the group consisting of alkyl, aryl, cycloalkyl and alkylaryl, with a carbon chain length between 1 and 6 carbon atoms, and N is a polyfunctional amino moiety. L may also have additional linking groups, such as groups of esters, ethers, ureas or urethanes.
2. 2. The crosslinking agent of claim 1, wherein the polyfunctional amino moiety is selected from the group consisting of urea, substituted urea, thiourea, melamines, benzoguanimines, dihydroxyethylene ureas, acetoguanimines, cyclohexylcarboguanamines, N, N'-dimethyl ureas, alkoxynitriles, acetylenediols, dicyandiamides , guanilureas, glycolurils, amides, carbamates, the reaction products of these compounds with aldehydes, and condensates thereof.
3. 3. The crosslinking agent of claim 1, wherein the polyfunctional amino moiety is selected from the group consisting of triazines, triazoles, diazines, guanos, guanadines.
4. 4. The crosslinking agent of claim 1, wherein the polyfunctional amino moiety comprises an alkoxylated aminoplast or aminoresin.
5. 5. The crosslinking agent of claim 1, wherein the polyfunctional amino moiety is selected from the group consisting of portions containing alkylated and methylolated glycoluril mixture, urea and urea containing portions.
6. 6. The crosslinking agent of claim 1, wherein the polyfunctional amino moiety is selected from the group consisting of melamine, melamine-formaldehyde, glycoluril-formaldehyde and urea portions.
7. 7. The crosslinking agent of claim 6, wherein the group -L- is CH2, CHR or CHR 'CHR "-, where R, R' R" are hydrogen or an alkyl group.
8. 8. A method for preparing a crosslinking agent with carbamate functionality, which comprises reacting a polyfunctional amino compound with a compound having reactive groups with polyfunctional amino and with a primary carbamate compound or compound having groups convertible to carbamate.
9. 9. The method of claim 8, wherein a carbamate convertible compound is used, which further comprises converting the convertible group to carbamate, to a carbamate functionality.
10. 10. The method of claim 8, wherein the reactive groups in aminoresin are converted to carbamate functionality by reaction of the groups with phosgene and then reacted with amine or ammonia.
11. ll. The method of claim 8, wherein the reactive groups in aminoresin are converted to carbamate by reaction of the groups with an isocyanate with primary carbamate functionality.
12. 12. The method of claim 8, wherein the reactive groups on the aminoresin are esterified with an alkyl carbamate.
13. 13. The method of claim 8, wherein the reactive groups on the aminoresin are reacted with alkyl carbamate at an elevated temperature in the presence of a catalyst.
14. 14. The method of claim 8, wherein the reactive groups on the aminoresin are formed by the reaction of epoxy with a hydrogen of the amine group, followed by conversion of the hydroxyl group to a carbamate group.
15. 15. A coating composition comprising a) a resin or material having more than one reactive group with carbamate functionality, and b) a crosslinking agent comprising one or more carbamate groups or groups convertible to carbamate and a polyfunctional amino moiety having the formula O -N L 0-C NHR f wherein L is alkyl, aryl, cycloalkyl and alkylaryl with a carbon chain length between l and ß carbon atoms and N is a polyfunctional amino moiety with one or more amino groups.
16. 16. The coating composition of claim 14, wherein the polyfunctional amino moiety is selected from the group consisting of primary amines, secondary amines, alkylamines, alkylated carbamates, alkoxyamines, and mixtures thereof.
17. 17. The coating composition of claim 14, wherein the polyfunctional amino moiety is selected from the group consisting of urea resins, substituted urea resins, thiourea resins, melamines, benzoguanamines, dihydroxyethylene ureas, acetoguanimines, cyclohexylcarboguani inas, N, N '- dimethylureas, acetylenediureas, dicyandiamides, guanilureas, glycolurils, amides, carbamates, the reaction products of these compounds with aldehydes, and condensates thereof.
18. 18. The coating composition of claim 14, wherein the polyfunctional amino moiety is selected from the group consisting of triazines, triazoles, diazines, guanamines and guanadines.
19. 19. The coating composition of claim 14, wherein the polyfunctional amino moiety is an aminoplast portion.
20. 20. The coating composition of claim 14, wherein the polyfunctional amino compound is selected from the group consisting of a mixture of alkylated and methylolated glycolurils, urea and urea-containing portions.
21. 21. The coating composition of claim 14, wherein the resin or material having reactive functionality with the carbamate is selected from the group consisting of polyurethane polyesters, addition polymers, polyester-polyurethane graft copolymers, aminoplastoe, and mixtures thereof.
22. 22. A method for coating a substrate, comprising a) applying to a substrate, a coating composition comprising a resin or material having more than one group reactive with carbamate functionality and a crosslinking agent comprising one or more carbamate groups or groups convertible to carbamate and a polyfunctional amin portion having the formula O IN -NL-0-C-MHR, wherein L is alkyl, aryl, cycloalkyl alkylaryl with a carbon chain length between 1 and carbon atoms and N is a polyfunctional amino moiety with one or more amino groups, and R is alkyl or cycloalkyl co between 1 and 6 carbon atoms; and b) cure the coating when baking at temperatures between 180 aF and 310 = F (82.2 and 154.4 aC), between 15 and 45 minutes.