MX2007001797A - Clearcoat paint composition - Google Patents

Abstract

A coating composition including an aqueous dispersion of a copolymerization product of a mixture of monomers including carbamate-functional and (meth)acrylic monomers, some having carboxylic acid-functionality. The monomer mixture is essentially free of hydroxyl monomer. The coating can be applied on a polycarbonate substrate. The coating composition may be a clearcoat coating composition, preferably an automotive clearcoat coating composition. The invention provides a method of producing such a coating and application on a substrate, particularly as a basecoat/clearcoat composite coating, with the coating composition of the invention preferably being at least the clearcoat of the composite coating. If the substrate is a polycarbonate, the clearcoat can be applied directly on the substrate without any primer or basecoat.

Description

COMPOSITION OF TRANSPARENT LAYER PAINT FIELD OF THE INVENTION The present invention relates to thermosetting transparent layer compositions, and more particularly, to automotive topcoat coatings.

BACKGROUND OF THE INVENTION Curable, or thermosetting, coating compositions are widely used in the coating art, in particular for finishing coatings in the automotive or industrial coatings industry. Mixed basecoat-clearcoat coatings are particularly useful as topcoats for which exceptional gloss, depth of color, sharpness of image or special metallic effects are desired. The automotive industry has made extensive use of these coatings for automotive bodies. Automotive clearcoats must meet many performance requirements. They should be soft and shiny to provide the desired aesthetic appearance. They must also be durable, both to preserve the appearance of coating and to protect the steel substrate, by resisting scratches and color alteration and also degradation of UV light in sunlight, environmental attack, and heat.

In the new era of automotive design and production, polycarbonate materials have become increasingly popular as an alternative material for use in automotive body components. Polycarbonate materials usually have acceptable levels of effort and clarity, but lack high levels of abrasion resistance and chemical resistance. Carbamate functional materials have found particular utility in coating compositions as crosslinkable resins. Clearcoat compositions containing carbamate-functional acrylic polymers can provide significant advantages over other compositions, such as hydroxy functional acrylic / melamine coating compositions as a solution to the environmental attack problem. Environmental attack, or acid attack, results in spots or marks on or in the coating that often can not be removed. Although such polymers and compositions containing carbamate functional materials provide a significant improvement over the prior art, improvements are still desired in some areas. In particular, it would be advantageous to provide polymers that exhibit the ability to rework polycarbonate materials as well as steel and other substrates, at the same time possessing the positive characteristics of environmental attack and performance of carbamate-functional acrylics. This would allow a low performance VOC coating system. It would also be advantageous to provide polymers exhibiting the ability to be used in an aqueous dispersion that can be applied to polycarbonate surfaces. Thus, there is a need for coating compositions having improved coating and adhesion capabilities that can be applied using existing equipment in plants currently configured to handle more traditional coating technology. Said coating composition must still provide a cured coating having the desired physical properties.

BRIEF DESCRIPTION OF THE INVENTION In one embodiment, the present invention provides a process for coating a substrate with a mixed low volatile emission coating. The process includes applying a primer coating composition on a substrate and curing the primer composition to form a primer coating layer. A basecoat coating composition is applied over the primer coating layer, and a clearcoat coating composition is applied over the basecoat coating composition. The applied basecoat and clearcoat compositions are cured to form a mixed coating layer. At least one of the primer coating compositions, base coat and clear coat includes a water based dispersion comprising an aqueous emulsion of copolymerized acrylic monomers, methacrylic monomers, and carbamate functional monomers. The dispersion is essentially free of hydroxyl monomer. In another embodiment, the present invention provides a method of coating a polycarbonate substrate. The method includes preparing a composition comprising an aqueous dispersion of copolymerized acrylic monomers, methacrylic monomers, and carbamate functional monomers. Preferably, the dispersion is essentially free of hydroxyl monomer. The composition is applied to a polycarbonate substrate and cured. In various embodiments, the dispersion is prepared by copolymerizing at least one carbamate functional monomer with a functional carboxylic acid monomer in a solvent. The resulting solution is salted with a mine and used to form a dispersion in water. In a particularly advantageous embodiment, the coating composition of the invention is a clearcoat coating composition, preferably an automotive clearcoat coating composition. The invention further provides an article, such as an automotive vehicle, having a surface coated with a coating derived from the coating composition of the invention, in particular a mixed coating having a basecoat layer and a clearcoat layer, and a method of producing said coating on a substrate, in particular as a mixed base coat / clear coat, with the coating composition of the invention of preferably forming at least the transparent layer of the mixed coating. In various embodiments, the article comprises a polycarbonate material.

DETAILED DESCRIPTION OF THE INVENTION The following description of the preferred embodiment (s) is merely exemplary in nature and in no way should limit the invention, its application or uses. "A" and "an" as used herein indicate "at least one" of the article is present; a plurality of said articles may be present, when possible. "Approximately" when applied to values indicates that the calculation or measurement allows some slight inaccuracy in the value (with some approach to accuracy in the value, approximately or reasonably close to the value, almost). If, for some reason, the inaccuracy provided by "about" otherwise is not understood in the art with this ordinary meaning, then "approximately" as used herein indicates a possible variation of up to 5% in value. The clearcoat composition of the present invention includes an aqueous dispersion of a copolymer of carbamate-functional (meth) acrylate monomers which are copolymerized with other acrylic or methacrylic monomers, some preferably having acid functionality. The dispersion is essentially free of hydroxyl monomer. The term "(meth) acrylate" as used herein, refers to both acrylate and methacrylate. The polymers include both relatively low molecular weight oligomers and relatively high molecular weight polymers. The term "copolymers" is contemplated to include oligomers and polymerized polymers of more than one kind of monomer. It will be appreciated that the term "function, as used in this disclosure, refers to the potential for entanglement to occur after the formation of a polymeric emulsion with an external entanglement agent.A carbamate group according to the invention can be represented by the structure wherein R 'is H or alkyl. Preferably, R 'is H or alkyl of 1 to about 4 carbon atoms, and more preferably R' is H (a primary carbamate). In various embodiments, carbamated propyl acrylic monomers such as In various other embodiments, the copolymer of the present coating composition has at least one monomer unit that includes the condensation product of a group ethylenically unsaturated carboxylic acid and glycidyl ester of a mixture of tertiary acids having 9 to 11 carbon atoms having at least one methyl group on the α-carbon. In an alternate preferred embodiment, at least one monomer unit includes the polymerization product of the condensation product of a polymerizable glycidyl ester or ether and a mixture of tertiary acids having 9 to 11 carbon atoms having at least one methyl group in the a-carbon. Mixtures of tertiary acids having 9 to 11 carbon atoms having at least one methyl group on the a-carbon are available under the trademark VERSATIC ™ acid, and the glycidyl ester of VERSATIC ™ acid (also commonly called neodecanoic acid) is available under the trademark CARDURA® Resin E-10 from Shell Oil Company. Examples of polymerizable acids include, without limitation, acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, and itaconic acid, and monoalkyl anhydrides and esters of the dysfunctional acids. Examples of glycidyl esters and ethers include, without limitation, glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether. With particular reference to a preferred acrylic polymer, then, the carbamate functionality can be conveniently introduced by polymerizing a monomer having a carbamate group. It is also possible to polymerize with a monomer having functionality that can be reacted to supply a carbamate group after polymerization. Examples of polymerizable addition monomers having carbamate functionality include, without limitation, carbamate propyl acrylate (CPA), carbamate propyl methacrylate (CPMA), and carbamate ethyl methacrylate (CEMA). Carbamate functionality can be introduced to an acrylic polymer by a number of reactions, including, without limitation, converting hydroxyl groups to carbamates by other methods, such as those set forth in Ohrbom, et al., U.S. Pat. 6,160,058, and McGee et al., U.S. Patent. 5,726,244, both are incorporated herein by reference. Hydroxyl groups may arise from reacting a carboxylic acid group with a glycidyl compound or reacting glycidyl functionality with a carboxylic acid. In a preferred embodiment, the acrylic polymer has an equivalent weight (with respect to the carbamate functionality) of up to about 650 grams / equivalent, more preferably up to about 520 grams / equivalent, still more preferable up to about 435 grams / equivalent, more preferable to about 370 grams / equivalent, and most preferably up to about 350 grams / equivalent. The acrylic polymer preferably has an equivalent weight (with respect to the carbamate functionality) of at least about 260 grams / equivalent, more preferably at least about 290 grams / equivalent, and still more preferably at least about 310 grams / equivalent . The acrylic polymer preferably has equivalent weight on the scale of 260 to 650 grams / equivalent, even more preferable 290 to 370 grams / equivalent, and much preferable 310 to 350 grams / equivalent. The polymer or acrylic polymers used as secondary dispersions (at least partially neutralized and then dispersed in water) must have a weight average molecular weight of at least about 2,400, preferably at least about 3,000, more preferable at least about 3,500 , and in particular preferable at least about 4,000. The weight average molecular weight can be determined by gel permeation chromatography using standard polystyrene. In addition, the weight average molecular weight is preferably up to about 10,000, more preferably up to about 12,000, and even more preferably up to about 15,000. The acrylic polymer having carbamate functionality has an equivalent weight, based on the carbamate or functionality preferably up to about 1,000 grams per equivalent, more preferably up to about 800 grams per equivalent, and still more preferable up to about 600 grams per equivalent. The carbamate equivalent weight is preferably at least about 350 grams per equivalent. A primary dispersion of acrylic carbamate resin could have a molecular weight in millions. The equivalent weight of these resins could be higher, for example, at least 1,500 g / carbamate and most preferably approximately 2,000 g / carbamate.

In various embodiments, the present invention provides polymerization of a monomer mixture that includes at least one functional carboxylic acid monomer or at least one monomer having a group that becomes an acid group after the polymerization, such as an anhydride group . Examples of functional acid or functional anhydride monomers include, without limitation, α-, β-ethylenically unsaturated monocarboxylic acids containing 3 to 5 carbon atoms such as acrylic, methacrylic, crotonic acids, and optionally, the esters of those acids; a-, β-ethylenically unsaturated dicarboxylic acids containing 4 to 6 carbon atoms and the anhydrides, monoesters such as maleic anhydride, maleic acid monomethyl ester, and fumaric acid, and optionally, the diesters of those acids; monomers containing a carboxyl group; sorbic, cinnamic, vinyl furoic, a-chlorosorbic, p-vinylbenzoic, maleic, fumaric, aconitic, atropic and itaconic acids; and functional acid derivatives of copolymerizable monomers, such as the hydroxyethyl acrylate ester medium of an anhydride, such as succinic acid. Other preferred half esters include lower alkyl esters containing 1 to 6 carbon atoms such as itaconic monomethyl ester, butyl acid itaconate, methyl fumarate, butyl fumarate, methyl acid maleate and butyl acid maleate. In various embodiments, a functional acidic monomer is preferably included in an amount of about 5% a about 25% by weight of the monomers being polymerized, and preferably from about 12% to about 25% by weight of the monomers being polymerized. Acid functionality can also be provided by other known means, such as by reaction of a hydroxyl group with a cyclic anhydride or by hydrolysis of an ester, such as by hydrolysis of a tert-butyl methacrylate monomer unit. Alternatively, it may be preferred to include an acid functional monomer such as maleic acid, methacrylic acid or crotonic acid, or an anhydride monomer such as maleic anhydride or itaconic anhydride which can be hydrated after polymerizing to generate acidic groups. The acrylic polymer can be polymerized using other co-monomers. Further representative examples of suitable esters of acrylic, methacrylic and crotonic acids include, without limitation, those esters of the reaction with cycloaliphatic alcohols containing 1 to 20 carbon atoms, such as acrylates, methacrylates and crotonates of methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, lauryl, stearyl, cyclohexyl, trimethylcyclohexyl, tetrahydrofurfuryl, stearyl, sulfoethyl and isobornyl. Representative examples of other polymerizable ethylenically unsaturated monomers include, without limitation, such compounds as anhydrides, monoesters and fumaric, maleic and itaconic diesters with alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol and tert-butanol. Representative examples of vinyl polymerization monomers include, without limitation, such compounds as vinyl act, vinyl propionate, vinyl ethers such as vinyl ethyl ether, vinyl and vinylidene halides, and vinyl ethyl ketone. Representative examples of aromatic or heterocyclic aliphatic vinyl compounds include, without limitation, such compounds as styrene, α-methyl styrene, vinyl toluene, tert-butyl styrene, and 2-vinyl pyrrolidone. The co-monomers can be used in any combination. The acrylic polymer or polymers can be prepared using conventional techniques, such as by heating the monomers in the presence of a polymerization initiating agent and optionally chain transfer agents. The polymerization is preferably carried out in solution, although it is also possible to polymerize the acrylic polymer by volume. In preferred embodiments of the present invention, the dispersions are formulated by a primary dispersion process or a secondary dispersion process. Using a primary dispersion process, an emulsion is made by directly polymerizing a carbamate functional monomer, for example, carbamate propyl acrylic monomer, with the other co-monomers in water. The aqueous mixture is provided having a suitable surfactant together with an appropriate polymerization initiator such as, for example, ammonia persulfate. Alternatively, using a secondary dispersion process, the carbamate functional monomer it is polymerized with functional acid co-monomers and others in an appropriate solvent solution. The solvent solution is subsequently titrated with an appropriate amine and neutralized. The resulting polymer salt is then added in water to form an aqueous dispersion that can be used in clearcoat coating compositions, basecoat coating compositions, and pigment grinding compositions. Non-limiting examples of said salt amines are dimethylenol amine (D EA), 2-amino-2-methyl propanol (AMP), ammonia, triethanolamine, triethyl amine, diethyl amine. The solvent or solvent mixture is usually heated to the reaction temperature and the monomers and initiator (s) and optionally chain transfer agent (s) are added at a controlled rate over a period of time, typically about 100%. two to about six hours. The polymerization reaction is usually carried out at temperatures from about 20 ° C to about 200 ° C. The reaction can be conveniently performed at the temperature at which the solvent or solvent mixture refluxes, although under its own control a temperature below reflux can be maintained. The initiator must be chosen to equal the temperature at which the reaction is carried out, so that the half-life of the initiator at that temperature should preferably be no more than about five minutes. Additional solvent can be added concurrently. The mixture is usually maintained at the reaction temperature after complete the additions over a period of time to complete the polymerization. Optionally, additional initiator can be added to ensure complete conversion of monomers to polymer. Typical initiators are organic peroxides such as dialkyl peroxides such as di-t-butyl peroxide, peroxyesters such as t-butyl peroctoate and t-butyl peracetate, peroxydicarbonates, diacyl peroxides, hydroperoxides such as t-butyl hydroperoxide, and peroxycetales; azo compounds such as 2,2'-azobis (2-methylbutanonitrile) and 1,1''-azobis (cyclohexanecarbonitrile); and combinations of these. Typical chain transfer agents are mercaptans such as octyl mercaptan, or n- or tert-dodecyl mercaptan; halogenated compounds, thiosalicylic acid, mercaptoacetic acid and dimeric alpha-methyl styrene. Although aqueous coating compositions that are free of regulated volatile organic compounds (VOCs) are preferred, a solvent may optionally be used in the coating composition used in the practice of the present invention. In general, the solvent can be any organic solvent and / or water. In a preferred embodiment, the solvent includes a polar organic solvent. More preferably, the solvent includes one or more organic solvents selected from polar aliphatic solvents or polar aromatic solvents. Still more preferably, the solvent includes a ketone, ester, acetate, aprotic amide, aprotic sulfoxide, or a combination of any of these. Examples of Useful solvents include, without limitation, methyl ethyl ketone, methyl isobutyl ketone, m-amyl acetate, ethylene glycol butyl acetate, propylene glycol monomethyl ether acetate, xylene, N-methylpyrrolidone, mixtures of aromatic hydrocarbons, and mixtures of these. In another preferred embodiment, the solvent is water or a mixture of water with small amounts of co-solvents. In general, co-solvents are organic solvents miscible in water that can be up to about 50%, based on the total amount of volatile materials (ie, more organic water solvents). In a preferred embodiment, the water is at least about 10%, more preferably at least about 15%, still more preferable at least about 20%, and even more preferably at least about 25% by weight of the total amount of volatile material. The organic phase of the coating composition includes the polymer having a sufficient amount of the carboxylic acid and carbamate functionalities and a sufficient amount of the water-miscible solvent to form a colloidal emulsion of the water. The organic phase also includes an oxygenated hydrogen bonding solvent under, which advantageously reduces the viscosity of the coating composition. In a preferred embodiment, the coating composition has a viscosity of 200 centipoise or less. Coating compositions at this viscosity can be applied using the Same application equipment as it is used with traditional high solids coating technology. Accordingly, the monomers used to prepare the acrylic or other polymer are selected and distributed to achieve the desired viscosity, and in conjunction with the molecular weight of the polymer and the water miscible solvent or solvent mixture are likewise selected to achieve the desired viscosity . The volatile organic content (VOC) of the coating composition, as measured according to the EPA Method 24, is preferably about 3.5 pounds / gallon or less, more preferably about 3.2 pounds / gallon or less, and even more preferably about 3.0 pounds / gallon or less (without water). (The VOC values used herein are those calculated without water). The VOC is minimized as much as possible by using the minimum amount of organic solvent together with the maximum amount of water to obtain the desired viscosity. The coating composition preferably contains one or more crosslinking agents that react with the acrylic polymer after applying the coating composition to form a cured coating. The composition preferably includes at least one entanglement agent that is reactive with carbamate functionality. Interlacing agents have two or more groups reactive with the polymer, and the interlayer advantageously has an affinity for water. That is, the entanglement agents preferably have a polar group or groups.

A certain amount of entanglement agents without affinity to water may also be included. The interleaver can be monomeric, oligomeric or polymeric. Examples of entanglement agents include, without limitation, aminoplast crosslinkers. The aminoplast interlayer is advantageously a monomeric melamine formaldehyde resin, preferably partially alkylated, in particular preferably partially methylated. Melamine formaldehyde resins having imino content are also useful. The transparent layer composition preferably includes at least about 10% by weight, more preferably at least about 15% by weight, of the interlayer, based on the non-volatile carrier. "Non-volatile vehicle" refers to the film-forming components. In preferred embodiments, the interleaver is at least about 5%, more preferably at least about 10% by weight of the non-volatile carrier. It is also preferred for the interleaver to be up to about 40%, more preferably up to about 30% by weight of the non-volatile vehicle. The interleaver is preferably from about 5% to about 40%, more preferably from about 10% to about 35%, and still more preferably from about 15% to about 35% by weight of the non-volatile carrier. The clear coat coating composition may include one or more catalysts to enhance the cure reaction, and it preferably includes a catalyst for the reaction of the aminoplast curing agent and a catalyst for the reaction of the polyisocyanate curing agent. Suitable catalysts for the reactions of the aminoplast curing agent include, without limitation, alkylsulfonic acids, arylsulfonic acid and alkylarylsulfonic acids, such as methane sulphonic acid, g-toluene sulfonic acid, dinonylnaphthalene sulfonic acid, dodecylbenzene sulfonic acid, phosphoric acid and their esters such as phosphate esters of phenyl acid, butyl phosphate and hydroxy phosphate; monobutyl maleate, boron trifluoride etherate, trimellitic acid, and triflic acid. Catalysts of strong acid are often blocked, for example, with an amine. Additional agents, for example surfactants, stabilizers, humidifying agents, rheology control agents, fillers, pigments, dyes, fungicides, dispersing agentsAdhesion promoters, UV absorbers, hindered amine light stabilizers, and the like as are known to those skilled in the art of coating formulations can be included and contemplated within the scope of the invention. Although such additives are well known in the prior art, the amount used must be controlled to avoid adversely affecting the coating characteristics. In various embodiments, the coating of the present invention is applied to polycarbonate substrates. The invention provides a high level of adhesion between the cured coating and the polycarbonate substrate at the same time avoiding or minimizing the use of non-reactive volatile components, such as solvents. Preferred polycarbonate substrates for use with the present invention include thermoplastic polycarbonate materials. Typical examples of polycarbonate resins are obtained by the reaction of aromatic dihydroxy compounds with phosphene, as well as those obtained by the reaction of aromatic dihydroxy compounds with carbamate precursors such as diaryl carbonates. The term "polycarbonate resin" should also include aromatic polycarbonate resins, including polyester carbonates obtained from the reaction products of a dihydroxy phenol, a carbamate precursor and a dicarboxylic acid such as terephthalic acid and isophthalic acid. In a preferred embodiment, the coating composition of the invention is a coating composition for an automotive vehicle or part thereof. Car lots can include polycarbonate materials, as well as steel and other materials commonly used in the industry. Among the classes of useful automotive coating compositions are primers and surfactants, primers, base layers, and clear coats. Transparent layers are particularly preferred. The coating compositions can be coated on an article of a vehicle, or other substrate, 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 automotive bodies and the like, spray coating is preferred. In various embodiments, the coating composition is used as the clear coat of a lighter mixed color coating. The pigmented basecoat composition on which it is applied may be any of a number of types well known in the art, and does not require detailed explanation herein. Polymers known in the art as useful in basecoat compositions include acrylics, vinyls, polyurethanes, polycarbonates, polyesters, alkyds and polysiloxanes. Preferred polymers include acrylics and polyurethanes. In a preferred embodiment of the invention, the basecoat composition also utilizes a carbamate functional acrylic polymer. The basecoat polymers may be thermoplastic, but are preferably crosslinkable and comprise one or more types of interlacing functional groups. Such groups include, for example, hydroxy, isocyanate, amine, epoxy, acrylate, vinyl, silane and acetoacetate groups. These groups can be masked or blocked in such a way that they are unlocked and available for the entanglement reaction under the desired cure conditions, usually elevated temperatures. Useful crosslinkable functional groups include epoxy, acid, anhydride, silane and acetoacetate groups. Preferred crosslinkable functional groups include hydroxy functional groups, acid functional groups and amino functional groups.

The basecoat polymers can be self-interlacing, or they can require a separate crosslinking agent that is reactive with the functional groups of the polymer. When the polymer comprises hydroxy functional groups, for example, the entanglement agent can be an aminoplast resin, isocyanate and blocked isocyanates (including isocyanurates), and functional acid or anhydride crosslinking agents. The clearcoat coating composition is usually applied wet-on-wet in a basecoat coating composition as is widely practiced in the industry. A preferred embodiment provides a method of coating a polycarbonate substrate with the aqueous dispersion of the present invention. The aqueous dispersion can be a basecoat coating composition or a clearcoat coating composition. It is contemplated that both the basecoat and the clearcoat coating compositions comprise aqueous dispersions. In various modalities, a substrate is first coated with a primer, such as an electroconductive primer coating known in the art. A basecoat coating composition is applied to the primed substrate and can be flamed for a short period of time. The clearcoat coating composition is then applied over the basecoat coating. The clearcoat coating is allowed to flame for a short period of time before being baked and cured to form a mixed coating layer. Yes the substrate is a polycarbonate, the transparent layer can be applied directly on the substrate without any primer or base coat. The coating compositions described herein are preferably subjected to conditions to thereby cure the coating layers. Although various methods of curing can be used, heat curing is preferred. In general, heat curing is performed by exposing the coated article to elevated temperatures provided primarily by sources of radioactive heat. Curing temperatures will vary depending on the particular blocking groups used in the crosslinking agents; however, they usually vary between 90 ° C and 180 ° C. In a preferred embodiment, the cure temperature is preferably between 115 ° C and 150 ° C, and more preferably at temperatures between 115 ° C and 140 ° C for a blocked acid catalyzed system. For a blocked acid catalyzed system, the cure temperature is preferably between 80 ° C and 100 ° C. The healing time will vary depending on the particular components used, and physical parameters such as the thickness of the layers; however, typical cure times vary from 15 to 60 minutes, and preferably 15 to 25 minutes for blocked acid catalyzed systems and 10 to 20 minutes for unblocked acid catalyzed systems. The healing times can also be expressed as time after the metal temperature reaches the temperature of Bake ("metal temperature"). For example, the healing time can be from 5 to 60 minutes, preferably from 10 to 30 minutes. Once cured, a mixed layer transparent layer on base layer of the present invention produces a film having attack and adhesion performance. Unlike similar formulations in the prior art, the present invention provides a coating suitable for application on polycarbonate that is very glossy and transparent with minimal haze and has a high level of solvent resistance. The clearcoat coating composition may include additional carbamate functional compounds. Such carbamate functional compounds include, without limitation, any of those described in the U.S.A. Nos. 6,160,058, 6,084,038, 6,080,825, 5,994,479, the descriptions of which are incorporated herein by reference. In particular, the composition may include a functional carbamate or functional urea material comprising at least two functional groups, at least one of which is a carbamate or urea group which is the reaction product of (1) a hydroxyl group of a first compound which is the result of a ring opening reaction between a compound with an epoxy group and a compound with an organic acid group and (2) cyanic acid or a compound containing carbamate or urea group. The coating composition may include another resinous material, for example one or more of the carbamate materials functionalities described in Ohrbom, et al., patent of E.U.A. No. 6,165,618; Green, and others, patent of E.U.A. No. 5,872,195; McGee, and others, patent of E.U.A. No. 5,854,385; Green, and others, patent of E.U.A. No. 5,852,136; Ohrbom, and others, patent of E.U.A. No. 5,827,930; Menovcik, et al., Patent of E.U.A. No. 5,792,810; McGee, and others, patent of E.U.A. No. 5,770,650; Ohrbom, and others, patent of E.U.A. No. 5,766,769; Bammel, et al., Patent of E.U.A. No. 5,760,127; Menovcik, et al., Patent of E.U.A. No. 5,744,550; Rehfuss, et al., Patent of E.U.A. No. 5,719,237; Green, patent of E.U.A. No. 5,693,724; Green, patent of E.U.A. No. 5,693,723; Menovcik, patent of E.U.A. No. 5,659,003; Briggs, patent of E.U.A. No. 5,639,828; Rehfuss, et al., Patent of E.U.A. No. 5,336,566; Ohrbom, and others, patent of E.U.A. No. 6,541,594; and Ohrbom, et al., U.S. Patent. No. 6,362,285, each of which is incorporated herein by reference. The carbamate functional material can be a compound or an oligomer (i.e., with up to ten or more units of repeating monomer). Preferably, the carbamate functional material has a molecular weight (for a compound), or number-average molecular weight (for an oligomer) of up to about 2,000, preferably up to about 1,800. Primer and surface active agent compositions may further include one or more pigments and typically include one or more fillers. The basecoat and topcoat compositions of one layer also include one or more color pigments and / or one or more special effect pigments, including metallic sheet pigments and pearlescent pigments. Inks can be inked clearcoat. 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.

EXAMPLES ACRYLIC POLYMERS WITH CARBAMATE MONOMER (WATER): Polymer 1.

Table 1 To a reactor containing 94.8 g of propylene glycol monopropyl ether at 140 ° C, a mixture of 16.7 g of acrylic acid, 54.8 g of carbamate propyl acrylate, 63.9 g of n-butyl methacrylate, 68.6 g of 2-ethylhexyl acrylate was added. , 64.7 g of styrene in 8.4 g of propylene glycol monopropyl ether for four hours. After a waiting period of about 30 minutes, a mixture of 4 g of t-butyl peroxy acetate and 4 g of mineral spirits was added in about 30 additional minutes to complete the reaction. After another waiting period of about 1 hour, the contents were cooled to 70 ° C and 12.4 g of dimethylethanolamine and 8.4 g of deionized water were added. After approximately 20 minutes of agitation, 160 g of deionized water is charged, producing a resin dispersed in water at 28% solids. It was found that the GPC molecular weight (measured against a polystyrene standard) was approximately Mn 5.570, Mw 14.440 with a polydispersity of 2.5. The equivalent weight is calculated as 850 g / carbamate and the neutralization amount was 60%. The theoretical Tg of the resin (determined using the Fox equation) is 22.9 ° C.

Polymer 2 Table 2 To a mixture of 95 g of butyl cellosolve and 20 g of deionized water in a reactor maintained at 105 ° C, a mixture of 59.5 g of carbamate propyl acrylate, 61 g of 2-ethylhexyl methacrylate, 36.2 g of acrylic acid was added. , 32.5 g styrene, 111.3 g of n-butyl acrylate in 1 g of ethylene glycol monobutyl ether, and 4.7 g of t-butyl peroxy 2-ethylhexanoate in 23 g of ethylene glycol monobutyl ether for three hours. After a waiting period of about 30 minutes, 1.2 g of t-butyl peroxy-2-ethylhexanate in 11.6 g of Butyl Cellusolve is added in about 30 additional minutes to complete the reaction. After another waiting period of about 1 hour, the reactor is cooled to about 70 ° C and 30.1 g of dimethylethanolamine is added to the reactor. 1 g of ethylene glycol monobutyl ether. After stirring for about 30 minutes, it is dispersed in 500 g of deionized water to obtain a resin dispersed in water at 30% NV having an equivalent weight of 870 g / carbamate. It is neutralized at 68% and has a theoretical Tg (determined using the Fox equation) of 1.1 ° C. It was found that the GPC molecular weight (measured against a polystyrene standard) was approximately Mn 6,120, Mw 13,870 with a polydispersity of 2.3.

Polymer 3 Table 3 To 308.5 g of deionized water in a reactor maintained at 90 ° C, a well stirred mixture of 188 g of deionized water, 6.1 g of Abex® EP-110 surfactant (available from Alcolac Inc.), 36.3 g of carbamate was added. propyl acrylate, 203 g of n-butyl acrylate, 50 g of n-butyl methacrylate, 67.9 g of methyl methacrylate, and 0.9 g of ammonium persulfate in 36.3 g of deionized water for 2.5 hours. The reaction mixture was maintained at 90 ° C for a further 2 hours and then cooled to 35 ° C. 21.8 g of 20% of 2-amino-2-methyl-1-propanol in deionized water, 11.4 g of Piuracol® P410 (available from BASF Corporation), 14.5 g of 2-ethylhexyl alcohol, and g of deionized water to achieve a final emulsion at 35.5% solids. The theoretical Tg of the resin (determined using the Fox equation) is -13.4 ° C, and the equivalent weight is 1.740 g / carbamate.

Table 4 Laboratory paint tests (4 mil) were made on polycarbonate sheets with coating compositions as presented in table 4. After 10 minutes at room temperature, the films were cured when heated at 110 ° C for 45 minutes. The films were very clear, bright, and held more than 20 double rubs of isopropanol, more than 200 double rubs of deionized water. After applying a cross weft of cuts, they do not show any perception of excess paint films, as evidence that the coatings have good adhesion to the polycarbonate substrate. The invention has been described in detail with reference to preferred embodiments thereof. However, it should be understood that variations and modifications may be made within the spirit and scope of the invention.

Claims (15)

REIVINDICACIO ES

1. A process for coating a substrate with a mixed VOC emission coating, the process comprising: applying a primer coating composition on a substrate and curing the primer coating composition to form a primer coating layer; applying a base coat coating composition on the primer coating layer; applying a clearcoat coating composition on the basecoat coating composition; and curing the applied basecoat and clearcoat coating compositions to form a mixed body coating layer, wherein at least one of the primer coating composition, the basecoat coating composition and the coating composition of The transparent layer comprises a water-based dispersion comprising an aqueous emulsion of copolymerized (meth) acrylate monomers and carbamate functional monomers, the dispersion being further essentially free of hydroxyl monomer.

2. - The process according to claim 1, wherein the dispersion is prepared by copolymerizing with emulsion at least one monomer selected from the group consisting of

3. - The process according to claim 1, wherein the dispersion is prepared by copolymerizing carbamate propyl (meth) acrylate and an acid functional co-monomer in a solvent, salting the resulting polymer with an amine, and adding water to form a dispersion watery

4. - The process according to claim 1, wherein the primer coating layer is electroconductive.

5. - The process according to claim 1, wherein the substrate comprises polycarbonate.

6. - The process according to claim 1, further comprising the use of at least one reactive interleaver with carbamate functionality.

7. - The process according to claim 6, wherein the interleaver is an aminoplast.

8. - A method of coating a polycarbonate substrate, the method comprising: preparing an aqueous dispersion of copolymerized carbamate functional monomer and (meth) acrylic co-monomers essentially free of hydroxyl monomer; add at least one interleaver; applying the composition to a polycarbonate substrate; and cure the composition.

9. The method according to claim 8, wherein the dispersion is prepared by copolymerizing at least one monomer selected from the group consisting of

10. The method according to claim 8, wherein the aqueous dispersion is prepared by copolymerizing carbamate functional monomer with at least one functional carboxylic acid monomer in a solvent, salting the resulting polymer with an amine, and forming a dispersion in water.

11. The method according to claim 8, further comprising mixing the dispersion with a hexamethoxymethylmelamine crosslinker (HMMM) and an acid catalyst.

12. The method according to claim 8, wherein the interleaver comprises an aminoplast resin.

13. - The method according to claim 8, further comprising copolymerizing a UV absorber.

14. - A transparent layer coating made in accordance with the method of claim 8.

15. - A basecoat coating made in accordance with the method of claim 8.