MXPA97006777A - Coating compositions, including alcoximethylene compounds, which have good exterior durability - Google Patents

Abstract

A coating composition comprising: (a) a first component comprising a compound which has joined at least one carbamate group, urea group or group convertible to a carbamate or urea group, and b) a second component which comprises a compound reactive with said carbamate or urea groups in component (a), which is a crosslinking agent with alkoxymethyl substitution

Description

COATING COMPOSITIONS, INCLUDING ALCOXIMETHYLENE COMPOUNDS, WHICH HAVE GOOD OUTER DURABILITY BACKGROUND OF THE INVENTION The invention relates to coating compositions, including crosslinking agents of alkyloxymethylurea for externally durable coating compositions.

Exposure to the Former Guild Curable coating compositions, such as thermosetting coatings, are widely used in coatings gremi. They are frequently used for final coatings in the automotive and industrial coatings industry. Color composite coatings plus transparent coatings are particularly useful as final coatings where exceptional shine quality, vividness of color, sharpness of the image, special metallic effects are desired. The automotive industry has extensively used these coatings for automotive body panels. However, the composite coatings of colo plus transparent layer require an extremely high degree of clarity in the transparent layer, to obtain the desired visual effect. High gloss coatings also require a low degree of visual aberration on the surface of the coating in order to obtain the desired visual effect, such as high sharpness of the image (DOI). As such, these coatings are particularly susceptible to a phenomenon known as environmental degradation. Environmental degradation manifests as spots or marks on, over, the finish of the coating, which frequently can not be removed by rubbing. Coatings containing hydroxy functional polymers crosslinked with alkoxy ethylurea crosslinking agent, historically provide good resistance to degradation. It is thought that poor durability results from autocondensation of urea generating uente < The ether is rapidly drilled. It is desirable to have a usable coating composition with alkoxymethylurea crosslinking agents, which provides a durable coating composition for the exterior. It has been determined that compounds with carbamate or urea functionality, crosslinked with alkoxymethylurea crosslinking agents provide films having good durability.

Summary of the Invention A coating composition comprising: (a) a first component that is a compound to which at least one carbamate or urea functional group has been attached, or a group convertible to a carbamate or urea group, and (b) a second component that is a compound reactive with said carbamate or urea groups in the component selected from the group consisting of crosslinking agents with alkoxymethylurea substitution.

Detailed Description of the Invention The coating composition of the present invention comprises a compound (a) selected from the group consisting of oligomers and polymers to which more than one carbamate group or more than one group of urea has been attached, or more than one group convertible to a carbamate or urea group. The oligomer has a molecular weight between 148 and 2,000, the preferred molecular weight for the oligomers is between 900 and 1,092; the polymers have a molecular weight between 2,000 and 20,000, the preferred molecular weight for the polymers is between 4,000 and 6,000. Mixtures of said oligomers and polymers can be used as component (a). The molecular weight can be determined by the gas phase chromatography method, using a polystyrene standard. The carbamate or urea content of the polymer, at a molecular weight per equivalent of carbamate or urea functionality, will generally be between 200 and 1,200, and preferably between 300 and 800. The carbamate groups can be characterized generally by the formula 0 II - 0-C-NHR where R is H or alkyl, preferably 1 to 4 carbon atoms.

Preferably, R is H or methyl, and more preferably R is H.

The urea groups can be characterized generally by the formula O where R 'and R "each independently represent H or alkyl, preferably from 1 to 4 carbon atoms, or R' and R" could together form a heterocyclic ring structure ( for example, where R 'and R "form an ethylene bridge.) Groups that can be converted to carbamate include cyclic carbonate groups, epoxy groups, and n-saturated linkages Cyclic carbonate groups can be converted to carbamate groups , by reaction with ammonia or a primary amine, which opens the cyclic carbonate ring to form a β-hydroxycarbamate.The epoxy groups can be converted to carbamate groups by first converting to a cyclic carbonate group by reaction with C02. It can be carried out at any pressure, from atmospheric to supercritical pressures of C02, but preferably under high pressures (for example, 60-150 psi (4.22-10.55 kg / cm2)). for this reaction it is preferably between 60-150BC. Useful catalysts include any which activates an oxirane ring, such as tertiary amine or quaternary salts (eg, tetramethylammonium bromide), combinations of complex organotin halides and alkyl phosphonium halides (eg, (CH3) 3SnI, Bu4SnI , Bu "PI and (CH3) 4PI), potassium salts (e.g., K2C03, Kl), preferably in combination with crown ethers, tin octoate, calcium octoatc and the like. The cyclic carbonate group can then be converted to a carbamate group, as described above. Any unsaturated linkage can be converted to cathoxide groups by reacting first with peroxide to convert to an epoxy group, then with C02 to form a cyclic carbonate, and then with ammonia or a primary amine to form the carbamate. The oligomeric compound (a), having more than one group with carbamate functionality, has the general formula: where X is O, S or NH, R i is H or alkyl of 1 to 4 carbon atoms. The compounds useful as oligomeric component (a), according to the invention, can be prepared in a variety of forms. The carbamate can be primary, ending in a group of NH2, or secondary, ending in a group of NHR. In a preferred embodiment, the carbamate is primary. One way to prepare useful oligomeric compounds such as component (a) is to react an alcohol ('alcohol' is defined herein as having one or more OH groups) with more than one urea, to form a compound with carbamate groups. This reaction is obtained by heating a mixture of alcohol and ureas. This reaction is also carried out under heat, preferably in the presence of a catalyst, as is known in the art. Another technique is the reaction of an alcohol with cyanic acid, to form a compound with primary carbamate groups (for example, unsubstituted carbamates). The carbamates can also be prepared by reaction of an alcohol with phosgene and then ammonia, to form a compound having primary carbamate groups, or by reaction of an alcohol with a phosgene and then a primary amine, to form a compound having of secondary carbamate. Another way is to react an isocyanate (e.g., hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI)) with a compound such as a hydroxypropyl carbamate, to form an isocyanate derivative cu ißrpo with cr.r aatc. Finally, the carbamates can be prepared by a transcarbamylation method, wherein an alcohol is reacted with an alkyl carbamate (for example, methyl carbamate, carbamate, butyl carbamate *), to form a compound containing a group of primary carbamate. This reaction is carried out under heat, preferably in the presence of a catalyst, such as an organometallic catalyst (for example, dibutyltin dilaurate). Other techniques for preparing carbamates are known in the art and are described, for example, in "Esters of Carbamic Acid" (Carbamic Acid Esters), by P. Adams and F. Barón, Chemical Review, v. 65, 1965. Various alcohols can be used in the preparation of carbamates compounds that are useful as component (a), according to the invention. They generally have from 1 to 200 carbon atoms, preferably from 1-60 carbon atoms, and could be monofunctional or polyfunctional (preferably a functionality of 2 to 3), aliphatic, aromatic or cycloaliphatic. They could contain only OH groups or they could contain OH groups plus heteroatoms, such as O, S, Si, N, P and other groups such as ester groups, ether groups, amino groups or unsaturated sites. Examples of useful alcohols are: 1,6-hexanediol, 1,2-hexanediol, 2-ethyl-l, 3-hexanediol, ethylpropyl-1,5-pentanediol, 2-tet-ethyl-2,4-pentanediol , 2, 2, 4-trimethyl-l, 3-pentanediol, 2, 4, 7, 9-tetramethyl-5-decyl-4,7-diol, 1,3-dihydroxyacetone dimer, 2-butene-1, 4 -diol, pantothenol, dimethyl tartrate, pentaethylene glycol, dimethylsilyldipropanol and 2,2'-thiodiethanol. The polymeric compound (a) is selected from the group consisting of polymers of polysilane, polyester, epoxy, alkyd, urethane, acrylic and polyamide, and mixtures thereof, wherein the polymer has more than one carbamate functional group attached thereto. In a preferred embodiment, component (a) is an acrylic polymer with carbamate functionality, represented by the units repeated at random, according to the following formula: In the formula indicated above, R represents H or CH '. R 'represents H, alkyl, preferably of 1 to 6 carbon atoms, or cycloalkyl, preferably of up to 6 carbon atoms in the ring. It is to be understood that the terms alkyl and cycloalkyl include substituted alkyl and cycloalkyl, such as cycloalkyl or alkyl substituted by halogen. However, substituents that will have an adverse impact on the properties of the cured material should be avoided. For example, it is thought that ether bonds are susceptible to photoinduced hydrolysis, and should be avoided at sites that would place the ether link in the crosslinking matrix. The values x and y represent percentages of weight, where x is from 10 to 90% and preferably from 20 to 50%, and y is from 90 to 10% and preferably from 80 to 50%. In the formula, A represents repeated units derived from one or more monomers with unsaturated ethylene. Such monomers are known in the trade for copolymerization with acrylic monomers. These include alkyl esters of acrylic or methacrylic acid, for example, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, butyl methacrylate, isodecyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and the like; and vinyl monomers such as unsaturated m-tetramethylxylene isocyanate (which American Cyanamid sells as TMIß), vinyltoluene, styrene, styrenic derivatives, such as methylstyrene, t-butylstyrene and the like. L represents a divalent linking group, preferably an aliphatic linking group of 1 to 8 carbon atoms, cycloaliphatic or aromatic of 6 to 10 carbon atoms.

Examples of L include: - (CH2) -, ~ (CH2) 2-, - (CH2) 4- and the like. In a preferred embodiment, -L- is represented by -COO-L-, where L 'is a divalent linking group. Therefore, in a preferred embodiment of the invention, the polymer component (a) is represented by repeating units at random, according to the following formula: , where In this formula, R, R ', A, x and y are as defined above. L 'can be a divalent aliphatic linking group, preferably 1 to 8 carbon atoms, for example, - (CH2) -, ~ (CH2) 2-, - (CH2) 4- and the like, or a linking group divalent cycloaliphatic, preferably up to 8 carbon atoms, for example, cyclohexyl and the like. However, other divalent linking groups can be used, depending on the technique used to prepare the polymer. For example, if a hydroxyalkyl carbamate adduct is formed on an acrylic polymer with isocyanate functionality, then the linking group L1 would include a urethane linkage -NHCOO- as a residue of the isocyanate group. This acrylic polymer with carbamate functionality is described in US Pat. No. 5,356,669. UU , which is incorporated herein by reference. The polymer component (a) used in the composition of the invention can be prepared in a variety of ways. One way of preparing such polymers is to prepare an acrylic monomer having a carbamate functionality in the ester portion of the monomer. Such monomers are well known in the trade and are described, for example, in US Patents 3,479,328, 3,674,838, 4,126,747, 4,279,833 and 4,340,497. UU , the disclosures of which are incorporated herein by reference. A synthesis method includes the reaction of a hydroxy ester with urea, to form the carbamyloxy carboxylate (for example, carbamate modified acrylic). Another synthetic method reacts an unsaturated acid ester a and b with a carbamate hydroxy ester to form the carbamyloxy carboxylate. Yet another technique includes the formation of a hydroxylalkyl carbamate by reacting ammonia, or a primary or secondary diamine or amine with a cyclic carbonate, such as ethylene carbonate. The hydroxyl group in the hydroxyalkyl carbamate is then esterified by reaction with methacrylic or acrylic acid to form the monomer. Other methods of preparing acrylic monomers modified by carbamate are described in the guild, and they can also be used. The acrylic monomer can then be polymerized together with other monomers with unsaturated ethylene, if desired, by techniques well known in the art. An alternative way to prepare an acrylic polymer for use as component (a) in the composition of the invention is to react an already formed polymer, such as an acrylic polymer, with another component, to form a group with carbamate functionality attached to the polymer backbone , as described in US Pat. No. 4,758,632. UU , the revelation of which is incorporated herein by reference. One technique for preparing such acrylic polymers includes thermally decomposing urea (to emit ammonia and HNCO) in the presence of a hydroxyl-functional acrylic polymer or copolymer, to form an acrylic polymer with carbamate functionality. Another technique consists in reacting the hydroxyalkyl carbamate hydroxyalkyl group with the isocyanate group of an isocyanate-functional vinyl or acrylic monomer to form the carbamate-functional acrylic. Acrylics with isocyanate functionality are known in the guild and are described, for example, in the Patéate;,,., 25 a • > '.. L, the revelation of which is incorporated here by reference. Isocyanate vinyl monomers are well known in the trade and include unsaturated m-tetramethyl isocyanate n (q > >, American Cyanamid as TMI®). Another technique is that of reacting the cyclic carbonate group, in an acra-CO even with cyclic carbonate, with ammonia, with the purpose of forming the acrylate with carbamate functionality. Acrylic polymers with cyclic carbonate functionality are known in the art and are described, for example, in US Patent 2,979,514. UU., The disclosure of which is incorporated herein by reference. A more difficult, but feasible, way to prepare the polymer would be to transesterify an acrylic polymer with a hydroxyalkyl carbamate. Groups capable of forming urea groups include amino groups which can be converted to urea groups by reaction with a monoisocyanate (for example, methyl isocyanate), to form a secondary urea group, or with cyanic acid (which can formed in situ by thermal decomposition of urea), to form a primary urea group. This reaction preferably occurs in the presence of a catalyst, as is known in the art. An amino group can also be reacted with phosgene and then ammonia to form a compound having primary urea group (s), or by reaction of an amino group with phosgene and then a primary amine, to form a compound having urea groups high school. Another method is to react an isocyanate with a hydroxyurea compound, to form an isocyanate derivative covered with urea. For example, one isocyanate group in toluene diisocyanate can be reacted with hydroxyethylethyleneurea, followed by reaction of the other isocyanate group with an excess of polyol to form a hydroxycarbamate. The composition of the invention is cured by the reaction of component (a) with carbamate functionality or with urea functionality, with a component (b) containing one or more functional groups that are reactive with the carbamate or urea groups of the component (a), and is a crosslinking agent of alkoxymethyl'5. The crosslinking agents can be formed by various methods. A common method includes obtaining ureas by isocyanate and amine reaction, where an aliphatic or aromatic isocyanate is reacted with an aromatic amine or primary or secondary aliphatic amine, to produce a urea compound. To obtain the alkoxymethylurea, the urea is reacted with formaldehyde to form the methylolated shell, where the reaction is catalyzed by either acid or base, followed by a condensation reaction that releases water and results in the formation of a methylene bridge. The condensation reaction is catalyzed with acid. The methylol compounds produced by these reactions are relatively stable under neutral or alkaline conditions, but have condensation, forming polymeric compounds under acidic conditions. It is desirable to further react the free methylol groups with an alkoxy to form alkoxymethyl groups to make the compounds more stable. With the replacement of the hydrogen of the methylol compound with alkyl groups, the material is more soluble in organic solvents and is more stable. The reaction is catalyzed with acid and is carried out in the presence of excess alcohol. The urea may be a di, tri or tetra substituted methylolurea. The presence of methylol groups makes the urea susceptible to hydrolysis and the formation of unstable ether bridges. Therefore, it may be desirable to use other urea initiator materials to form the crosslinking agent of alkoxymethylurea. Ethylene urea can be used instead of urea, to form the alkoxymethylurea, and to minimize the reactive sites in the urea. In this case, ethyleneurea is prepared from urea, ethylenediamine and formaldehyde. Generally, ethyleneurea is prepared by reacting an excess of ethylenediamine with urea and then introducing the methyl with formaldehyde. Ethyleneurea provides only two reactive sites for methylolation, in contrast to urea, which can provide up to four sites for methylolation. Additionally, the alkoxymethylurea can be formed from diurea crystals. In the guild it is sometimes considered that the diuißa crystals are agents of rheology control. The diary crystals are reacted with formaldehyde, followed by reaction with an alcohol, to form the alkoxymethylurea. Another method of forming "alkoxymethyl" is a glycoluril. Glycoluril is formed by reacting urea and glyoxal in a molar ratio of 2% to 50%. The preferred alkyloxymethyloureas for the purpose of the present invention include N, N-dimethylurea; N, N, N-trimethylurea; and alkoxymethylureas having an alkoxy with a carbon chain length of 1 to 12 carbon atoms. Particularly preferred are the alkoxymethylureas having an alkoxy with a carbon chain length between 1 and 4. In a coating composition, the alkoxymethylurea reacts with the compound (a) with carbamate or urea functionality, to form a crosslinked film. The carbamate or urea portion reacts with the alkoxy group in the urea crosslinking agent to form a urethane linkage. As component (a) a compound with carbamate or urea functionality is used instead of a hydroxyl-functional compound, to minimize the formation of ether bridges in a coating composition. The ratio of functionality equivalents of carbamate or urea to ethylalkoxy functionality in a coating composition is between 40:60 to 95: 5, preferably 50:50. Generally, the compound with carbamate functionality or with urea functionality, is present in an amount between 70 and 90 percent, by weight, and the alkoxymethylurea is present in an amount between 30 and 10 percent, by weight, based on total weight of the coating composition. A coating composition, according to the present invention, can be used, for example, in the form of a substantially solid powder, or a dispersion, and optionally a solvent can be used in the composition of the present invention. Frequently, it is desirable that the composition be in a substantially liquid state, which can be obtained with the use of a ui = r-íven ?. In general. depending on the solubility characteristics of the components (a) and (b), the solvent can be any organic solvent and / or water. In a preferred embodiment, it is a polar organic solvent. More preferably, the solvent is a polar aliphatic solvent a polar aromatic solvent. Still more preferably, the solvent is a ketone, ester, acetate, alcohol, aprotic amide, aprotic sulfoxide or aprotic amine. Examples of useful solvents include methyl ethyl ketone, methyl isobutyl ketone, -amyl acetate, ethylene glycol butyl ether acetate, propylene glycol monomethyl ether acetate, xylene, n-methylpyrrolidone or mixtures of aromatic hydrocarbons. In another preferred embodiment, the solvent is water or a mixture of water with small amounts of aqueous cosolvents. The composition of the invention may include a catalyst for increasing or accelerating the curing reaction. Frequently, it may be desirable to employ a strong acid catalyst to increase or accelerate the curing reaction. Such catalysts are well known in the trade and include, for example, p-toluenesulfonic acid, dinonylnaphthalenedisulfonic acid, dodecylbenzenesulfonic acid, phenyl acid phosphate, monobutyl maleate, butyl phosphate and hydroxyphosphate ester. Additional ingredients may be added to the coating composition, such as, but not limited to, pigments, reagent control agents, flow control additives, ultraviolet light absorbers and light stabilizers of the clogged amine. In a preferred embodiment of the invention, the composition of the invention is used as a pigmented coating composition or clearcoat coating composition. In such a composition, the solvent may be present in the composition of the invention in an amount of about 0.01 percent, by weight, to about 99 percent, by weight, preferably about 10 percent, by weight, to about 60. percent, by weight, and more preferably from about 30 percent, by weight, to about 50 percent, by weight. The coating compositions may be coated in the article by any of a number of techniques well known in the art. Among these are, for example, spray coating, dip coating, roller coating, curtain coating and the like. For car body panels, spray coating is preferred. In a particularly preferred embodiment, the composition of the invention is used as a clear and / or colorless coating composition on a pigmented basecoat, as part of a colored composite coating plus clearcoat. Such composite coatings are popular for their vividness of color and appearance of a shiny liquid surface. They have found a particularly wide acceptance in the field of automotive coatings. The composition of the invention can also be used as the base layer of a colored composite coating plus transparent layer. Other pigmented base coat compositions for such composite coatings are well known in the trade, and do not require detailed explanation here. Among the polymers known to be useful in basecoat compositions are acrylics, vinyls, polyurethanes, polycarbonates, polyesters, alkyds and polysiloxanes. A preferred polymer in an acrylic polymer. After an article is molded, emptied or coated with the layers described above, the composition is subjected to conditions to cure the coating layers. Although various coating methods can be used, thermal curing is preferred. Generally, thermal curing is carried out by exposing the coated article to high temperatures, provided mainly by sources of heat by radiation. The curing temperatures will vary, depending on the functional polymer or aminoplast used, but are generally within a range of 93 SC and 177aC, and are preferably between J 1BC and 141aC. The curing time will vary, depending on the particular components used and the physical parameters, such as the thickness of the layers; however, typical curing times vary between 15 to 60 minutes. The invention is also directed to a method for improving the durability of coating films using alkoxymethylurea compound. The method comprises combining the alkoxymethylurea compound with a carbamate or urea functional compound, to form the coating composition, and subsequently applying the coating to a substrate and forming a film. The coating film is heated to form a cured film. The invention is further described in the following non-limiting examples.

EXAMPLES Example 1 Acrylic Polymer with Functionality of Carbamate To a clean, dry, 5 liter flask equipped with a stirrer, condenser and thermocouple were added 417.0 grams of propylene glycol methyl ether. Heat was applied and reflux was maintained. In a separate vessel were added sequentially, 600.0 grams of propylene glycol methyl ether, 0.34 grams of 4-methoxyhydroquinone and 730.5 grams of carbamate propyl methacrylate. The vessel was stirred and heated slightly, so that homogeneity was achieved before each addition, until a solution was obtained. In a second vessel, 595.8 grams of 2-ethylhexyl acrylate, 384.3 grams of styrene, 211.5 grams of 2-ethylhexyl methacrylate and 319.8 grams of t-butyl peroxyacetate (50%) were added. The contents of the first and second containers were combined and mixed until they were homogeneous. This mixture was added to the flask at a constant speed, for a period of about 4 hours.

For 30 months a mixture of 32.1 grams of t-butyl perosyacetate (50%) and 60.0 grams of aromatic 100 was uniformly added. The reflux was maintained for a period of 150 minutes, followed by cooling.

Example 2 1 Dodecylbenzenesulfonic acid blocked with diisopropanolamine. 2 Tinuvin 123, by Ciba Giegy Corp. 3 Tinuvin 1130, by Ciba Giegy Corp. 4 Byk 320, by Byk Chemie.

Example 3 - (Comparison) Composition of Coating with Acrylic Resin with Functionality of OH and Melamine 1 Dodecylbenzenesulfonic acid blocked with diisopropanolamine, 2 Tinuvin 123, by Ciba Giegy Corp. 3 Tinuvin 1130, by Ciba Giegy Corp. Byk 320, by Byk Chemie.

Example 4 (Comparison) Composition of Coating with Acrylic Resin with OH Functionality and Alkoxymethylurea Adduction Agent 1 Dodecylbenzenesulfonic acid blocked with diisopropanolamine. 2 Tinuvin 123, by Ciba Giegy Corp. 3 Tinuvin 1130, by Ciba Giegy Corp. 4 Byk 320, by Byk Chemie.

Table 1 Comparative Durability Results * 1 year of exposure in Florida ** Exposure to QUV-2500 hours

Claims (22)

1. Claims The claims that we claim are: 1. A coating composition comprising: (a) a first component comprising a compound to which is attached at least one functional group selected from the group consisting of a carbamate group, a group of urea, a group that can be converted to carbamate or urea, and mixtures thereof; Y (b) a second component comprising a compound reactive with said carbamate groups in component (a), selected from the group consisting of crosslinking agents with alkoxymethylurea substitution.
2. 2. A composition, according to claim 1, wherein component (a) comprises a compound selected from the group consisting of oligomers to which more than one functional group selected from the group consisting of carbamate groups, urea groups and groups that can be converted to carbamate or urea, and said oligomers have a molecular weight between 148 and 2,000, polymers to which more than one functional group selected from the group consisting of carbamate groups, urea groups and functional groups has been linked convertible to carbamate or urea groups, and said polymers have a molecular weight of more than 2,000, and mixtures of said polymers and oligomers.
3. 3. A composition, according to claim 1, wherein said first component is a polymer with carbamate or urea functionality, selected from the group consisting of polymers of polysilane, polyester, epoxy, alkyd, urethane, acrylic and polyamide, and mixtures of these.
4. 4. A composition, according to claim 2, wherein said polymer comprises a polymer backbone to which a group with carbamate functionality has been bonded plus df1, and said first component is represented by randomly repeating units, according to the formula: where R R represents H or CH3, R 'represents H, alkyl or cycloalkyl, L represents a divalent linking group, A represents repeat units derived from one or more monomers with unsaturated ethylene, X represents 10 to 90%, by weight, and Y represents 90 to 10%, by weight.
5. 5. A composition, according to claim 4, comprising one or more monomers with unsaturated ethylene and more than one monomer has a carbamate group attached thereto.
6. 6. A composition, according to claim 4, wherein said monomers with unsaturated ethylene comprise one or more acrylic monomers.
7. 7. A composition, according to claim 5, wherein said acrylic monomers comprise a carbamate group.
8. 8. A composition, according to claim 5, wherein 10-90% of said monomers with unsaturated ethylene are acrylic monomers.
9. 9. A composition where -L- is represented by the formula -COO-L ', where L' is a divalent linking group.
10. 10. A composition, according to claim 1, wherein component (a) comprises an oligomer to which more than one functional group selected from the group consisting of carbamate groups, urea groups and convertible carbamate or urea groups has been attached. , and said oligomer has a molecular weight between 148 and 2,000.
11. 11. A composition, according to claim 1, wherein the compound (b) is selected from the group consisting of alkoxymethylureas, wherein the alkoxy group has a carbon chain length between 1 and 12 carbons.
12. 12. A composition, according to claim 1, wherein the compound (b) is formulated from compounds selected from the group consisting of urea, glycolurils, ethyleneurea and diurea crystals.
13. 13. A method of producing an article with a colored composite coating plus transparent layer, comprising the steps of applying a colored coating composition to a substrate, and applying a clear coating composition on the colored coating composition, wherein the composition Transparent coating is a curable coating composition comprising: (a) a first component comprising a compound to which more than one functional group selected from the group consisting of carbamate groups, urea groups and carbamate convertible groups has been attached or urea, and (b) a second component comprising a compound reactive with said carbamate or urea groups of component (a), which is an alkoxymethylurea.
14. 14. A method, according to claim 13, wherein the component (a) comprises a compound selected from the group consisting of oligomer "to which more than one functional group selected from the group consisting of carbamate groups, urea groups, was attached. and groups convertible to carbamate or urea, and said oligomers have a molecular weight between 148 and 2,000, and the polymers have been joined more than one functional group selected dl irupo consistent ßrt carbamate and urea groups, and said polymers have a weight molecular weight of more than 2,000, and mixtures of said polymers and oligomers.
15. 15. A method, according to claim 14, which donates component (a) comprises an olomer which is a primary carbamate compound.
16. 16. A method, according to claim 14, wherein the component. (a) comprises a carbamate functional polymer selected from the group consisting of polymers of polysilane, polyester, epoxy, alkyd, urethane, acrylic and polyamide, and mixtures thereof.
17. 17. A method, according to claim 14, wherein the component (a) comprises a polymer backbone to which more than one carbamate functional group has been attached, and said first component is represented by the randomly repeated units, according to with the formula: where R represents H or CH3, R 'represents H, alkyl or cycloalkyl, L represents a divalent linking group, A represents repeated units derived from one or more monomers with unsaturated ethyl, X represents 10 to 90%, by weight, and Y represents 90 to 10%, by weight.
18. 18. A method, according to claim 17, wherein component (a) comprises a polymer that includes acrylic monomers, wherein more than one of said acrylic monomers comprises a carbamate group.
19. 19. A method, according to claim 17, wherein -L- is represented by the formula -CO0-L ', where L' is a divalent linking group.
20. 20. A method, according to claim 17, wherein the component (b) is selected from the group consisting of alkoxymethylurea, wherein the alkoxy group of the urea has a carbon chain length between 1 and 12 carbons.
21. 21. An article comprising a substrate having therein a colored composite coating plus transparent layer prepared according to the composition of claim 1.
22. 22. A method for improving the outer durability of the transparent layer of a color composite coating plus transparent layer comprising combining: (a) a first component comprising a compound to which has bound at least one functional group selected from the group consisting of in carbamate groups, urea groups and groups convertible to carbamate or urea, and (b) a second component comprising a compound reactive with said carbamate or urea groups of component (a), selected from the group consisting of crosslinking agents with substitution of alkoxymethylurea, to form the coating composition and subsequently apply the coating to a substrate, forming a film, heating the coating film to cure the film.