MXPA97007325A - Transparent layers resistant to stripe, containing microparticles with reactive surface, and methods for - Google Patents

Abstract

The present invention is a coating composition having good scratch resistance and a method for increasing the scratch resistance of a coating composition. The coating composition comprises (A) a binder system that forms a film containing a crosslinkable resin and optionally a crosslinking agent for the crosslinkable resin, (B) substantially colorless inorganic or carbide microparticles, within a range of particle sizes. about 1 to 1000 nanometers before incorporation into the coating composition, and the microparticles react with the crosslinkable part of the film forming binder system; (C) a solvent system for the crosslinkable resin, an optional crosslinking agent; microparticles, wherein the crosslinkable resin is present in an amount of about 10 to about 80% by weight and the inorganic microparticles are present in an amount of 0.1 to 60% by weight to the sum of the weights of the crosslinkable resin, the optional crosslinking agent, and inorganic microparticles

Description

STRIP RESISTANT TRANSPARENT LAYERS, CONTAINING MICROPARTICLES WITH REACTIVE SURFACE, AND METHODS FOR THIS Field of the Invention The invention relates to a coating composition that exhibits good scratch resistance, and a method of improving the scratch resistance of a coating composition.

BACKGROUND OF THE INVENTION Clearcoat coating compositions, comprising the outermost automotive coating, are subject to damage caused by numerous elements. These elements include environmental precipitation, exposure to ultraviolet radiation emitted by sunlight, exposure to high relative humidity at high temperature, defects caused by small and hard objects, which result in scratching and pitting. A harder film can provide a clear coat that is more resistant to environmental degradation, although resulting in a film that is less scratch resistant. A softer film can provide a coating that is more resistant to scratching, with less resistance to degradation. Therefore, it is most preferable to produce a coating having an optimum mixture of characteristics in relation to various forms of resistance to damage. In order to be commercially successful, a siding should provide as many favorable features as possible. The sum of all the characteristics of any particular coating determines its value in the real world of automotive coatings. Therefore, an object of the present invention is to provide a clear coat composition that exhibits good scratch resistance without compromising the durability of the coating in other areas.

SUMMARY OF THE INVENTION The present invention is directed to a clearcoat composition having good scratch resistance and a method of improving the scratch resistance of a clearcoat coating composition. The scratch resistance of the coating is improved by the addition, to the coating composition, of reactive inorganic microparticles. The clear coat coating composition of the present invention comprises: (A) a film forming binder system, which contains a crosslinkable resin and, optionally, a crosslinking agent for the crosslinkable resin; (B) colorless inorganic microparticles, comprising a functionality capable of reaction with the crosslinkable resin, the microparticles, before incorporation into the coating composition, varied in size from about 1 to 1000 nanometers; (C) a solvent system for the crosslinkable resin and optional crosslinking agent; wherein the resin with crosslinking capacity is in an amount of 10 to 80%, by weight, and the inorganic microparticles are present in an amount of about 0.1 to 60%, by weight, preferably 5.0 to 40%, by weight, in base to the sum of the weights of the crosslinkable resin, the optional crosslinking agent and the inorganic microparticles.

Detailed Description of the Preferred Embodiment The coating composition of the present invention comprises a binder system containing a main resin with crosslinking capability. The crosslinkable resin can be any suitable crosslinkable resin for use in waterborne or substantially solvent based coating compositions. As used herein, the term "resin with crosslinking capability" is intended to include, not only resins capable of crosslinking with the application of heat, but also resins that are capable of crosslinking without the application of heat. Examples of such crosslinkable resin resins include thermoset acrylics, aminoplast agents, urethanes, carbamate, carbonate, polyesters, epoxies, silicones and polyamides. These resins, when desired, may also contain characteristics of functional groups of more than one kind, such as, for example, polyesteramides, urethane acrylates, carbamate acrylates, etc. As acrylic resins it refers to the addition polymers and copolymers, generally known, of acrylic and methacrylic acids and their ester derivatives, acrylamide and methacrylamide, and acrylonitrile and methacrylonitrile. Examples of the ester derivatives of acrylic and methacrylic acids are alkyl acrylates and alkyl methacrylates, such as ethyl, methyl, propyl, butyl, hexyl, ethylhexyl and lauryl acrylates and methacrylates, as well as similar esters, having up to 20 carbon atoms in the alkyl group. In addition, hydroxyalkyl esters can be easily employed. Examples of such hydroxyalkyl esters include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl-4-hydroxybutyl methacrylate, and mixtures of such esters having to about 5 carbon atoms in the alkyl group. When desired, various other unsaturated ethylene monomers can be used in the preparation of acrylic resins, and examples thereof include: vinylaromatic hydrocarbons, optionally including halogen substituents, such as styrene, α-methylstyrene, vinyltoluene, a-chlorostyrene; non-aromatic monoolefinic and diolefinic hydrocarbons which optionally include halogen substituents, such as isobutylene, 2,3-dimethyl-1-hexene, 1,3-butadiene, chloroethylene, chlorobutadiene and the like; and esters of organic and inorganic acids, such as vinyl acetate, vinyl propionate, isopropenyl acetate, vinyl chloride, allyl chloride, vinyl a-chloracetate, dimethyl maleate and the like. The polymerizable monomers indicated above are mentioned as representatives of the monomers containing CH2 = C < that can be used; but essentially, any copolymerizable monomer can be used. As aminoplast resins it refers to the condensation products, generally known, of an aldehyde with a substance containing amino or amido group, and among the examples of which are the reaction products of formaldehyde, acetaldehyde, crotonaldehyde, benzaldehyde and mixtures of these with urea, melamine or benzoguanimine. Among the preferred aminoplast resins are the etherified (ie, alkylated) products obtained from the reaction of alcohols and formaldehyde with urea, melamine or benzoguanimine. Examples of suitable alcohols for the preparation of these etherified products are: methanol, ethanol, propanol, butanol, isobutanol, t-butanol, hexanol, benzyl alcohol, cyclohexanol, 3-chloropropanol and ethoxyethanol. As urethane resins it refers to thermosetting resins, generally known, prepared from organic polyisocyanates and organic compounds containing active hydrogen atoms, as found, for example, in hydroxyl and amino portions. Some examples of urethane resins that are typically used in one component coating compositions are: isocyanate-modified alkyd resins. Examples of systems based on urethane resins that are typically used as two-component coating compositions include an isocyanate terminated prepolymer or organic polyisocyanate, in combination with a substance containing active hydrogen, such as in hydroxyl or amino groups, together with a catalyst (for example, organotin salt, such as dibutyltin dilaurate). The active hydrogen-containing substance in the second component is typically a polyester-polyol, a polyether-polyol or an acrylic polyol known for use in such two-component urethane resin systems. Polyester resins are generally known and are prepared by conventional techniques using polyhydric alcohols and polycarboxylic acids. Examples of suitable polyhydric alcohols are: ethylene glycol; propylene glycol; diethylene glycol; dipropylene glycol; butylene glycol; glycerin; trimethylolpropane; pentaerythritol; sorbitol; 1,6-hexanediol; 1,4-cyclohexanediol; 1,4-cyclohexanedimethanol; 1,2-bis (hydroxyethyl) cyclohexane and 2,2-dimethyl-3-hydroxypropionate. Examples of suitable polycarboxylic acids are: phthalic acid; isophthalic acid; acid terephthalic; trimellitic acid; tetrahydrophthalic acid; hexahydrophthalic acid; tetrachlorophthalic acid; adipic acid; azelaic acid; sebacic acid; succinic acid; maleic acid; glutaric acid; malonic acid; pimelic acid; 2,2-dimethylsuccinic acid; 3,3-dimethylglutaric acid; 2,2-dimethylglutaric acid; fumaric acid and itaconic acid. The anhydrides of the acids indicated above, when they exist, may also be employed and are encompassed by the term "polycarboxylic acid". In addition, substances that react in an acid-like manner to form polyesters are also useful. Such substances include lactones, such as caprolactone, propylolactone and methylcaprolactone, and hydroxy acids, such as hydroxycaproic acid and dimethylolpropionic acid. If a higher triol or water alcohol is used, a monocarboxylic acid may be used, such as acetic acid and benzoic acid in the preparation of the polyester resin. Further, it is intended that the polyesters include polyesters modified with fatty acids or glyceride oils of fatty acids (ie, conventional alkyd resins). Alkyd resins are typically produced by reacting the polyhydric alcohols, polycarboxylic acids and fatty acids derived from drying, separating and non-drying oils, in various proportions, in the presence of a catalyst, such as sulfuric acid or a sulfonic acid, to effect the esterification. Examples of suitable fatty acids include saturated and unsaturated acids, such as stearic acid, oleic acid, ricinoleic acid, palmitic acid, linoleic acid, linolenic acid, licánic acid and eleseaárico acid. Epoxy resins are generally known and refer to compounds or mixtures of compounds containing more than one 1,2-epoxy group of the formula O / \ -c-c-I I '(that is, polyepoxides). The polyepoxides can be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic. Examples of suitable polyepoxides include the polyglycidyl ethers of the polyphenol and / or polyepoxides which are acrylic resins containing pendant and / or terminal 1,2-epoxy groups. The polyglycidyl ethers of the polyphenols can be prepared, for example, by etherification of a polyphenol with epichlorohydrin or dichlorohydrin in the presence of an alkali. Examples of suitable polyphenols include: 1,1-bis (4-hydroxyphenyl) ethane; 2, 2-bis (4-hydroxyphenyl) propane; 1,1-bis (4-hydroxyphenyl) isobutane; 2, 2-bis (4-hydroxyphenyl) ethane; 2,2-bis (hydroxy-t-butylphenyl) propane; bis (2-hydroxynaphthyl) methane and the hydrogenated derivatives thereof. The polyglycidyl ethers of polyphenols of various molecular weights can be produced, for example, by varying the ratio of moles of epichlorohydrin to polyphenol. Epoxy resins also include the polyglycidyl ethers of mononuclear polyhydric phenols, such as the polyglycidyl ethers of resorcinol, pyrogallol, hydroquinone and pyrocatechol. Epoxy resins also include the polyglycidyl ethers of polyhydric alcohols, such as the reaction products of epichlorohydrin or dichlorohydrin with aliphatic and cycloaliphatic compounds containing two to four hydroxyl groups, for example, ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, propanediols, butanediols, pentanediols, glycerin, 1,2,6-hexanetriol, pentaerythritol and 2,2-bis (4-hydroxycyclohexyl) propane. Additional epoxy resins include polyglycidyl ethers of polycarboxylic acids, such as the polyglycidyl esters of adipic acid, phthalic acid and the like. It is also possible to use addition polymerized resins. These polyepoxides can be produced by the addition polymerization of epoxy-functional monomers, such as glycidyl acrylate, glycidyl methacrylate and ether-allyl glycidyl optionally in combination with monomers with unsaturated ethylene, such as styrene, α-methylstyrene, ethylethyrene, vinyl toluene, t-butyl styrene, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, ethacrylonitrile, ethyl methacrylate, methyl methacrylate, isopropyl methacrylate, isobutyl metaorilate and isobornyl methacrylate. The carbamate polymer can be represented by the units repeated at random, according to the following formula: In the formula indicated above, Rj represents H or CH3. R 2 represents H, alkyl, preferably from 1 to 6 carbon atoms, or cycloalkyl, preferably 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 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 40 to 60%, and y is from 90 to 10% and preferably from 60 to 40%. In the formula indicated above, 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), styrene, vinyltoluene and the like. L represents a divalent linking group, preferably an aliphatic of 1 to 8 carbon atoms, cycloaliphatic or aromatic linking group 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, component (a) of the polymer is represented by repeating units at random, according to the following formula: In this formula, Rx, R2 (A, x and y are as defined above, L * may be a divalent aliphatic linking group, preferably from 1 to 8 carbon atoms, for example, - (CH2) -, ~ (CH2 ) 2-, - (CH2) 4- and the like, or a divalent cycloaliphatic linking group, preferably of 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 isocyanate-functional acrylic polymer, then the linking group L 'would include a urethane bond -NHCOO- as a residue from the group of Isocyanate When desired, generally known crosslinking agents can be incorporated into a composition of the invention, particularly when the crosslinkable resin comprises a thermosetting resin containing amino or hydrogen functionality. As will be appreciated by a person having skill in the trade, the choice of crosslinking agent depends on several factors, such as compatibility with the resin that forms film, the particular type of functional groups in the resin that forms film, and the like. . The crosslinking agent is used to crosslink the film forming resin, either by condensation reactions or non-free radical addition reactions, or a combination of these two. When, for example, the thermoset reactants can be crosslinked in the presence of moisture or when the reactants include monomers having complementary groups capable of going into crosslinking reactions, then the crosslinking agent can be omitted, if desired. Representative examples of crosslinking agents include: blocked and / or unblocked diisocyanates, diepoxides, aminoplasts, phenol / formaldehyde adducts, carbamates, siloxane groups, cyclic carbonate groups and anhydride groups. Among examples of such compounds are melamine formaldehyde resin (including polymeric or monomeric melamine resin and partially or fully alkylated melamine resin), urea resins (e.g., methylolureas, such as ureaformaldehyde resin, alkoxyureas, such as butylated urea-formaldehyde resin), polyanhydrides (e.g., polysuccinic anhydride), and polysiloxanes (e.g., trimethoxysiloxane). Particularly preferred are aminoplast resins such as melamine formaldehyde resin or urea-formaldehyde resin. Even more preferred are aminoplast resins where one or more of the amine nitrogens is substituted with a carbamate group. When the aminoplast resins are used as the crosslinking agent, melamine-formaldehyde condensates, in which a substantial part of the methylol groups have been etherified by reaction with a monohydric alcohol, are particularly suitable. A coating composition of the invention contains substantially colorless and substantially inorganic microparticles dispersed in the coating composition. These inorganic microparticles, prior to incorporation into the coating composition, have an average diameter in the range of about 1.0 to about 1000 nanometers (eg, from about 1.0 to about 1000 millimicrons), preferably from about 2 to about 200 nanometers, and more preferably from about 4 to about 50 nanometers. The substantially inorganic microparticles, which are suitable for the coating composition of the present invention, prior to incorporation into the coating composition, are in the form of a sol, preferably an organosol, of the microparticles. A particularly effective type of substantially inorganic microparticles, for compositions of the invention, include a variety of silica sols of silica particles with a particle size that is within the range indicated above, and having the surface modifications described above. Suitable microparticles for compositions of the present invention include carbides and compounds that are substantially inorganic. For example, the substantially inorganic microparticles may comprise a core of essentially one single inorganic oxide, such as silica in colloidal, smoke or amorphous form, or alumina, or an inorganic oxide of one type on which an inorganic oxide is deposited from another kind. However, the appropriate inorganic microparticles for coating compositions of the current invention are normally essentially colorless, so as not to seriously interfere with the light transmission characteristics of the coating compositions when they are not pigmented. It should be understood that although the substantially inorganic microparticles can be differentiated or associated by physical and / or chemical means in aggregates, and although a certain sample of the microparticles will generally have particles that fall within a range of particle sizes, the substantially inorganic microparticles they will have an average diameter within the range of about 1 to about 150 nanometers. The substantially inorganic microparticles used as the starting material for incorporation into the coating composition should be of an appropriate form for dispersion in the coating composition, whereby, after dispersion, the substantially inorganic microparticles remain dispersed in stable form by a a period of time that is at least sufficient to prevent the use of the coating composition for the purpose for which it is intended. For example, a coating composition containing dispersed inorganic microparticles, depending on the size of the inorganic microparticles and the nature of the other components used to prepare the coating composition, in which dispersed inorganic microparticles tend to settle over a period of time. of time, but which can be redispersed, as for example, using conventional paint mixing techniques, is considered to fall within the scope of the present invention. A particularly desirable class of substantially inorganic microparticles for compositions of the present invention, includes sols of a wide variety of colloidal silicas, of small particles, with an average diameter of about 1 to 1000 nanometers (nm), preferably of about 2 to about 200 nm, and more preferably of about 4 to 50 nm, and these silicas have had modification of surface during and / or after the particles were initially formed. Said silicas can be prepared by a variety of techniques in a variety of ways, and among examples of which are organosols and mixed sols. In the form in which it is used herein, the term "mixed soles" is intended to include those colloidal silica dispersions in which the dispersion medium includes both an organic liquid and water. Said colloidal silicas of small particles, can be easily obtained, are essentially colorless, and have refractive indexes which make them suitable for combination with a variety of solvent systems and cross-linking resins, to form substantially transparent coating compositions, when the coating compositions have no dyes or pigments. In addition, silicas of appropriate particle size and having various degrees of hydrophobic, hydrophilic, organophobic and organophilic character can be employed, depending on the compatibility with the solvent system and crosslinking resin, in particular, which is use in the coating composition. The silicas that are ordinarily used in compositions of the invention include common colloidal forms, having final silica particles which, at least, prior to incorporation into the coating composition may contain on the surface portions containing carbon with chemical bonding. , as well as groups such as anhydrous Si02 groups, SiOH groups, various ionic groups that are physically associated or have chemical bonds within the surface of the silica, adsorbed organic groups and combinations thereof, depending on the particular characteristics of the silica desired. The microparticles can be reactive with the binder, either by their inherent reactivity (eg, the presence of SiOH groups) or this reactivity can be converted, using one of a wide range of alkoxysilane linking agents (eg, glycidylalkoxysilanes, isocyanatoalkoxysilanes, aminoalkoxysilanes and carbamylalkoxysilanes). The reactive groups of the silica allow the silica to be reacted in the crosslinkable resin, without further treatment, when a silane or aminoplast crosslinking agent is used. When the surface of the silica is not reactive with the crosslinking resin or the crosslinking agent, the inorganic particles are reacted with a binding agent comprising a compound having a functionality capable of covalently binding to the inorganic particles and have a functionality capable of crosslinking in the resin with crosslinking capacity, where both functionalities are reacted in a backbone of the binding agent. The backbone of the binding agent is a polyvalent linking group. Examples of the polyvalent linking groups are polyvalent radicals, such as silicone and phosphorus, alkyl groups, oligomers or polymers, such as acrylic, urethane, polyester, polyamide, epoxy, urea and alkyd polymers and oligomers. Examples of functionality that reacts with the inorganic particle include functionalities of hydroxyl, hydroxy ether, phenoxy, silane and aminoplast. Where a group with hydrophilic functionality is desired, as for use in a water-based coating, groups with hydrophobic functionality can be reacted with groups such as an acid to provide the hydrophilic functionality. These aggregated hydrophilic groups may or may not be crosslinked in the cured film. Reactive functionality with the crosslinkable resin includes functionalities of carbamate, isocyanate, carboxyl, epoxy, hydroxyl, amine, urea, amide, aminoplast and silane. For purposes of the present invention, the preferred reactive functionality is an oxyhydride, carbamate, isocyanate or aminoplast functionality. When necessary, these groups can be blocked prior to the reaction with the inorganic microparticles, then they can be deblocked to react with the crosslinking agent or crosslinkable resin. Alternatively, the reactive functionality with the crosslinking agent or crosslinkable resin can be incorporated into the binding agent after reacting in the microparticles. Preferred binding agents, for purposes of the present invention, have the formula A2 A, O-Si - A4X wherein Al t A2, A3 and A4 are the same or different, and are hydrogen, or alkyl of 1 to 20 carbons, alkoxyalkyl, wherein the alkyl group is 1 to 20 carbons. The SiOAi bond is able to hydrolyze and react with the surface of the inorganic particles. The group X comprises any functionality that can react with the crosslinkable resin or the crosslinking agent of the coating composition. Above, examples of such functionalities were indicated. Preferably, group X comprises carbamate, hydroxyl, epoxy or isocyanate functionality, more preferably carbamate. The hydroxy, amine and isocyanate binding agents can be obtained commercially. Examples of commercially available silane lioning agents include Dow Corning Additive No. 21, an aminomethoxysilane; Dow Corning Z-6040, a silane with glycidoxy functionality; and Silquist A1310, a silane with isocyanate functionality. Alternatively, the hydroxyl, hydroxy ether or silane is reacted in the silica by forming a colloidal dispersion of the silica in an alcohol, such as a lower monohydric alcohol, or alcohols containing ether, followed by the reaction of the silica with compounds for provide functionality that can react with the crosslinking resin or the crosslinking agent. Said functionality can be provided by forming a colloidal dispersion of the silica in an alcohol, such as a lower monohydric alcohol, examples of which include methanol, ethanol, n-propanol, isopropanol, n-butanol and ether containing alcohols, such as as a monomethyl ether of ethylene glycol, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, propylene glycol monobutyl ether and dipropylene glycol monobutyl ether. Said dispersions can be prepared by the controlled addition of an aqueous silica sol to the alcohol, while simultaneously stirring water, for example, by distillation, under conditions which are not sufficient to effect a substantial chemical reaction between the hydroxyl groups of the alcohol and the silanol groups of colloidal silica. The clearcoat compositions of the present invention may comprise a water-based or solvent-based system, or may be a powder or aqueous powder suspension system. The term "solvent-based system" is used herein in a broad sense and is intended to include true solvents, as well as liquid diluents for the cross-linking resin and the optional cross-linking agent, which are not true solvents for these components. The solvent system is organic, a mixture of organic solvents, a mixture of organic solvents and water, or water alone. When the solvent system comprises both water and an organic portion, the components are usually miscible in the proportions employed. The relationship between the solvent system and the crosslinkable resin depends on the relative natures of these materials and on the relative amounts used. Factors such as solubility, miscibility, polarity, and hydrophilic and hydrophobic character are factors that could be considered. In a preferred embodiment of the invention, the solvent is present in the clearcoat composition in an amount from about 0.01%, by weight, to about 99%, by weight, preferably from about 10%, by weight, to about 60% , by weight, and more preferably from about 30%, by weight, to about 50%, by weight. The clear coat composition used in the practice of the invention could include a catalyst to increase or accelerate the curing reaction. For example, when aminoplast compounds are used, particularly the monomeric melamines, such as component (b), a strong acid catalyst can be used 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. Other catalysts that could be useful in the composition of the invention are Lewis acids. Transparent coating compositions may also include optional ingredients, such as various fillers, plasticizers, antioxidants, surfactants, catalysts to promote drying or curing, flow control agents, thixotropes and additives for slip and / or pigment resistance. The coating compositions can be coated on the article by any of a number of techniques well known in the art. These include, for example, spray coating, dip coating, roller coating, curtain coating and the like. For car body panels, spray coating is preferred. The clear coating composition is applied to a substrate having a pigmented basecoating composition. The compositions of the pigmented base coat for said composite components are well known in the trade, and do not require to be explained in detail here. The polymers known in the art to be useful in basecoat compositions include acrylics, vinyls, polyurethanes, polycarbonates, polyesters, alkyd compounds and polysiloxanes. Among the preferred polymers are acrylics and polyurethanes. In a preferred embodiment of the invention, the composition of the base layer also uses an acrylic polymer with carbamate functionality. The base layer polymers preferably have crosslinking capability and, therefore, include one or more types of crosslinkable functional groups. Such groups include, for example, hydroxyl, isocyanate, amine, epoxy, acrylate, vinyl, silane and acetoacetate groups. These groups could be hidden or blocked in such a way that they are unblocked and available for the crosslinking reaction under the desired curing conditions, generally at elevated temperatures. Among the useful functional groups with cross-linking ability are the hydroxyl, epoxy, acid, anhydride, silane and acetoacetate groups. Among the preferred functional groups with crosslinking capability are the hydroxyl functional groups and the amino functional groups. The polymers of the base layer could have self-crosslinking capability, or they could require a separate crosslinking agent that is reactive with the functional groups of the polymer. When the polymer includes hydroxyl functional groups, for example, the crosslinking agent could be an aminoplast resin, isocyanate and isocyanates with blocking (including isocyanurates), and crosslinking agents with acid functionality or anhydride functionality.

After an article is coated with the layers described above, the composition is subjected to conditions for the coating layers to cure. Although various curing methods may be used, heat curing is preferred. Generally, heat curing is effected by exposing the coated article to elevated temperatures provided mainly by sources of radioactive heat. Curing temperatures will vary, depending on the particular blocking groups used in the crosslinking agents; however, they are generally in a range between 93 ° C and 177 ° C, and preferably between 121 ° C and 141 ° C. 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 have a range of 15 to 60 minutes The current invention is illustrated with the following non-limiting examples.

Examples EXAMPLE 1 Silane Binding Agent with Carbamate Functionality To a 1 liter flask, maintained under an inert atmosphere, 275.7 g of methyl amyl ketone, 205 g of 3-isocyanatopropyl-1-trimethoxysilane, and 0.16 grams of dilaurate were added. dibutyltin. Then, the system was heated to approximately 40 ° C. Then 119 grams of hydroxypropyl carbamate was added, followed by the addition of 14 grams of methyl amyl ketone. The system was maintained at about 40aC until the reaction was completed, as determined by infrared spectrometry. Then 10 grams of methanol were added. The final product has a theoretical non-volatile content of 50%, a carbamate functionality of 325 g / equ and a methoxy functionality of 108.3 g / equ (or 325 g / equ of Si (OMe) 3).

Example 2 Silica A with Functionality of Carbamate To 400 grams of colloidal silica (Nalco 1057, of Nalco colloids), 4 grams of water and 22.5 grams of the binding agent of Example 1 were added. This mixture was then placed in an oven at 60 ° C. (140BF) for 16 hours.

Examples 3A-3C Transparent Layer Compositions Example 3A Transparent Control Coat 264.1 grams of URECLEAR® 1 clearcoat without silica. 1 Ureclear® is a registered trademark of a transparent layer containing an acrylic resin with carbamate functionality, which can be obtained from BASF Corporation.

Example 3B Transparent Layer with Silica without Treatment 264.1 grams of URECLEAR® clear coat, as used in Ex. 3A, were combined, under agitation, with 62.85 grams of Nalco 1057 colloidal silica without the binding agent and 54.0 grams of methyl isoamyl ketone methyl-2-hexanone.

Example 3C Transparent Layer with Silica with Surface Treatment A 264.1 grams of URECLEAR® clear coat, as used in Ex. 3A, 62.85 grams of carbamate-functionalized silica of Example 2 were combined, with stirring, and 60 grams of methyl isoamyl ketone methyl-2-hexanone were added. These clearcoats were applied in a "wet" manner over a black basecoat with a high solids content, over primed, 10.2 cm x 30.5 cm (4 inches x 12 inches) primed panels. These panels were dried by evaporation at ambient temperatures, for 10 minutes, and then cured for 20 minutes at 132.22C (270SF). After 24 hours, the scratch and wear resistance was evaluated. The panels were subjected to a scratch and wear resistance test, where the person performing the test was not aware of the coating composition to which the test was made. The test method is Test Method FL-TM-BI-161-01, which is described below. The panels aged for 24 hours. Three panels were evaluated. The brightness of three areas of 3.8 cm x 10.2 cm (1.5 inches x 4 inches) in each panel was marked and measured with good brightness, image sharpness (DOl) and little or no dirt. The brightness was measured using the statistics mode on the brightness meter, measuring the initial brightness of each of the three areas, taking the average of at least three readings in each, with the beam perpendicular to the length of 10.2 cm (4 inches). The average initial brightness was measured, as well as the standard deviation of each brightness. The standard deviation was less than 0.5 brightness units, and the range of the three averages was less than 1.5 brightness units. A 50 mm x 50 mm square of 3M polishing paper was cut in half and placed in two felt squares, with the abrasive side removed from the felt. The two squares were mounted on the finger of the Croc meter with the felt between the finger of the Crockmeter and the abrasive paper. A constant orientation of the abrasive paper was maintained, in relation to the direction of wear. The two squares were fixed with a hose clamp. The panel was placed on the Crockmeter in such a way that the finger wears the panel in one of the three areas demarcated on the panel. The movement of the Crockmeter was parallel to the dimension of 10.2 cm (4 inches). The test surface was subjected to 10 double passes of the Crockmeter. The wear process was repeated in the other two areas of the panel, changing the abrasive paper each time. The brightness was measured again, in each of the three worn areas, by the same method as in the first brightness measurement. A higher degree of gloss retention indicates less scratching.

The results of the tests are indicated in Table 1. Table 1 Results of Scratch Resistance and Attrition of Ex. 3A-3C Example 4 Silane Binding Agent with Functionality of Polymeric Carbamate A carbamate resin with a hydroxyl functionality was prepared with a hydroxyl equivalency of 1650 g / equivalent at a non-volatile content of 95%. To 922 grams of acrylic with hydroxyl and carbamate functionality the following was added: Example 5 Silica B with Carbamate Functionality To 1500 grams of colloidal silica (Nalco 1057, Nalco colloids), 60 grams of the binding agent of Example 4 was added. This mixture was then placed in an oven at 60 ° C (140 ° F) for 16 hours. hours. This resulted in a colloidal silica dispersion with carbamate functionality, with a non-volatile content of 31.3%.

Examples 6A-6C Example 6A Transparent Gauge with Silica with Carbamate Functionality Sample 6A was prepared by adding 260.1 grams of carbamate-functionalized silica B, from Example 5, to 134.3 grams of the transparent layer URECLEAR®, a clear layer containing an acrylic resin with functionality of carbamate, sold by BASF Corporation, with a non-volatile content of 75.4%. This produced a clear layer with a 75% solid silica dispersion based on the weight of solid URECLEAR®.

Example 6B Transparent Silica Coating with Carbamate Functionality 208.0 grams of the carbamate functionalized silica B, from Example 5, were added to 277.5 grams of the transparent URECLEAR® layer, as described in Ex. 6A, with a non-volatile content of 72.4%. This produced a clear layer with a 30% solid silica dispersion based on the weight of solid URECLEAR®.

Example 6C Transparent, Silica Free Coating with Carbamate Function Transparent URECLEAR® Coating, as described in Ex. 6, with a non-volatile content of 54%. These transparent coats were spray applied in a "wet" manner on a black basecoat with a high solids content, on 10.2 cm x 30.5 cm (4 inches x 12 inches) electro-coated panels. These panels were cured for 20 minutes at 132.2aC (270fiF). After cooling, scratch and wear resistance was evaluated, using the test method described above (FL-TM-BI-161-01). A higher degree of gloss retention indicates less scratching.

Table 2 Scratch Resistance

Claims (21)

Claims l '. A clear coat coating composition, for automotive application, comprising
1. (A) a film-forming binder system, which contains a cross-linking resin and, optionally, a cross-linking agent for the cross-linking resin; (B) colorless carbide or inorganic microparticles, where the microparticles vary in size from about 1 to 1000 nanometers, prior to incorporation into the coating composition, and the microparticles are reactive with the crosslinking portion of the film forming binder system; (C) a solvent system for the crosslinkable resin, optional crosslinking agent; wherein the resin with crosslinking capacity is in an amount of about 10 to about 80%, by weight, and the inorganic microparticles are present in an amount of 0.1 to 60.0%, by weight, based on the sum of the weights of the crosslinkable resin, the optional crosslinking agent and the inorganic microparticles.
2. 2. The coating composition of claim 1, wherein the microparticles are selected from the group consisting of silica, fumed silica and colloidal silica.
3. 3. The coating composition of claim 1, wherein the microparticles vary in size from 2.0 to 200 nanometers.
4. 4. The coating composition of claim 1, wherein the microparticles are present in aggregates ranging in diameter from about 5 to 50 nanometers and are present in an amount between 5 and 40%, by weight, based on the sum of the weights of the resin with crosslinking capacity, the optional crosslinking agent and the inorganic microparticles.
5. 5. The coating composition of claim 1, wherein the inorganic particles comprise inorganic particles reacted with a binding agent, wherein the binding agent comprises a backbone portion which is a polyvalent linking group having there a first reactive functionality with the particles inorganic, and a second reactive functionality with the crosslinking agent.
6. 6. The coating composition of claim 5, wherein the binding agent comprises a polyvalent skeleton selected from the group consisting of phosphorus and silicone radicals, alkyl groups having a carbon chain length of about 1 to 12 carbon atoms, polymers and oligomers selected from the group consisting of polymers and oligomers of acrylic, polyester, polyether, urethane, urea, polyamide, epoxy and alkyd, and mixtures thereof; a first functionality in the skeleton, reactive with the inorganic particles, selected from the group consisting of functionalities of hydroxyl, phenoxy, hydroxyether, silane and aminoplast; Y a second functionality in the backbone, reactive with the crosslinking agent, selected from the group consisting of carbamate, hydroxyl, isocyanate, carboxyl, epoxy, amine, urea, amide, silane and aminoplast functionalities, which may be with or without blocking.
7. 7. The coating composition of claim 5, wherein the reactive functionality with the crosslinking agent comprises a carbamate functionality.
8. 8. The coating composition of claim 1, wherein the inorganic particles comprise a reactive functionality of SiOH on the surface of the particles.
9. 9. The coating composition of claim 7, wherein the crosslinking agent comprises silane or aminoplast functionality.
10. 10. The coating composition of claim 6 comprises an aminoplast crosslinking agent.
11. 11. A clearcoat coating composition, for automotive application, comprising (A) a film forming binder system, which contains a crosslinkable resin and, optionally, a crosslinking agent for the crosslinkable resin; (B) colorless carbide or inorganic microparticles, wherein the microparticles vary in size from about 1 to 1000 nanometers, and prior to incorporation into the coating composition, the microparticles are reacted with a binding agent, wherein the binding agent comprises a skeleton portion, which is a polyvalent linking group having there a first reactive functionality with the inorganic particles, and a second reactive functionality with the crosslinking portion of the film forming binder system; (C) a solvent system for the crosslinkable resin, optional crosslinking agent; wherein the crosslinkable resin is in an amount of about 10 to about 80%, by weight, and the inorganic microparticles are present in an amount of 0. 1 to 60.0%, by weight, based on the sum of the weights of the crosslinkable resin, the optional crosslinking agent and the inorganic microparticles.
12. 12. A method for improving the scratch resistance of a clear coat coating composition, for automotive use, comprising I) applying a pigmented coating composition to a substrate; II) forming a film of the coating composition applied in I); III) applying to the formed film of I) a clearcoat coating composition, wherein the clearcoat coating composition comprises (A) a film forming binder system, which contains a crosslinkable resin and, optionally, a crosslinking agent for the crosslinkable resin; (B) substantially colorless carbide or inorganic microparticles, ranging in size from about 1 to 1000 nanometers, prior to incorporation into the coating composition, and the microparticles are reactive with the crosslinking portion of the film forming binder system; (C) a solvent system for the crosslinkable resin, optional crosslinking agent and microparticles; wherein the resin with crosslinking capacity is present in an amount of about 10 to about 80%, by weight, and the inorganic microparticles are present in an amount of 0.1 to 60.0%, by weight, based on the sum of the weights of the resin with crosslinking capacity, the optional crosslinking agent and the inorganic microparticles; and IV) baking the base layer and the transparent layer, either separately or together, to form a cured film on the substrate.
13. 13. The method of claim 12, wherein the transparent layer composition applied to the substrate includes inorganic microparticles selected from the group consisting of silica, fumed silica and colloidal silica.
14. 14. The method of claim 12, wherein the transparent layer coating composition applied to the substrate includes microparticles ranging in size from 2.0 to 200 nanometers.
15. 15. The method of claim 12, wherein the transparent layer coating composition applied to the substrate includes inorganic particles comprising inorganic particles reacted with a binding agent, wherein the binding agent comprises a backbone portion which is a polyvalent linking group which there it has a first reactive functionality with the inorganic particles and a second reactive functionality with the crosslinking agent.
16. 16. The method of claim 12, wherein the transparent layer coating composition applied to the substrate includes as the binding agent for the microparticles, a compound comprising a polyvalent skeleton selected from the group consisting of phosphorus and silicone radicals, of alkyl with a carbon chain length of 1 to 12 carbon atoms, polymers and oligomers selected from the group consisting of acrylic polymers and oligomers, polyester, polyether, urethane, urea, polyamide, epoxy and alkyd, and mixtures thereof; wherein the first functionality reactive with the inorganic particles is selected from the group consisting of functionalities of hydroxyl, phenoxy, hydroxyether, silane and aminoplast; and the second reactive functionality with the crosslinking agent is selected from the group consisting of carbamate, isocyanate, carboxyl, epoxy, amine, urea, amide, silane and aminoplast functionalities.
17. 17. The method of claim 15, wherein the transparent layer coating composition applied to a substrate comprises a binding agent having a carbamate functionality reactive with the crosslinking agent.
18. 18. The method of claim 12, wherein the clearcoat coating composition applied to the substrate comprises inorganic particles comprising a reactive functionality with SiOH on the surface of the particles.
19. 19. The method of claim 17, wherein the transparent layer applied to the substrate includes a crosslinking agent comprising a silane or aminoplast crosslinking agent.
20. 20. The method of claim 12 or 15, wherein the microparticles are present in an amount between 5.0 and 40%, based on the total weight of the crosslinkable resin, optional crosslinking agent and microparticles.
21. 21. A method for improving the scratch resistance of a clearcoat coating composition for automotive use, comprising I) applying a pigmented coating composition to a substrate; II) forming a film of the coating composition applied in I); III) applying to the formed film of I) a clearcoat coating composition, wherein the clearcoat coating composition comprises (A) a film forming binder system, which contains a crosslinkable resin and, optionally, a crosslinking agent for the crosslinkable resin; , (B) colorless carbide or inorganic microparticles, wherein the microparticles vary in size from about 1 to 1000 nanometers, and prior to incorporation into the coating composition, the microparticles are reacted with a binding agent, wherein the binding agent comprises a skeleton portion, which is a polyvalent linking group having there a first reactive functionality with the inorganic particles, and a second reactive functionality with the crosslinkable portion of the film forming binder system; (C) a solvent system for the crosslinkable resin, optional crosslinking agent and microparticles; wherein the resin with crosslinking capacity is present in an amount of about 10 to about 80%, by weight, and the inorganic microparticles are present in an amount of 0.1 to 60.0%, by weight, based on the sum of the weights of the resin with crosslinking capacity, the optional crosslinking agent and the inorganic microparticles; and IV) baking the base layer and the transparent layer, either separately or together, to form a cured film on the substrate.