MXPA00001188A - Method for on-mold powder coating - Google Patents

Abstract

Method for on-mold surface coating fiberglass-reinforced molded articles during their manufacture with environmentally friendly and physiologically safe thermosetting unsaturated polyester on-mold coating powders which serve as replacements for liquid gel coats. The thermosetting coating powders employed are adapted to cure at low temperatures to avoid causing thermal damage to the heat sensitive plastic molds which must be reused over and over again, and to cure in the presence of atmospheric oxygen to enable over coating with liquid fill resins and fiberglass, which constitute the bulk of the finished article, without having the fill resins bleed through the powder coating film and detrimentally affect the overall quality of the surface finish.

Description

METHOD FOR COATING IN MOLDÉ ARTICLES MOLDED WITH A COATING POWDER LIKE A REPLENISHMENT OF LIQUID GEL COATING Field of the Invention This invention relates to the manufacture of articles molded from thermosetting resins with or without fiberglass reinforcement. More particularly, this invention relates to a method for in-mold coating the surface of molded articles during their manufacture with spray-dried thermosetting resins which serve as replenishments for liquid gel coatings, with articles having surface coatings formed in this manner on the same and with thermosetting powdered resins adapted for mold coating.

BACKGROUND OF THE INVENTION Liquid gel coating mold coating is a known technique for decorating or protecting the surface of a molded article formed from thermosetting resins, whether or not reinforced with glass fibers. In this technique, a liquid gel coating, which becomes the outer surface or skin of the molded article, is sprayed onto the inner wall of a female mold before molding the part. After the gel coating layer has sufficiently hardened, one or more layers of liquid thermosetting resin, with or without glass fiber reinforcement, constituting the volume of the finished article, and then spread or sprayed onto the gel coating. The layers are added and cured as needed to build the article to the desired thickness After the cure has advanced sufficiently and the gel coating and the fill resin layers are integral, the finished coated article is released from the mold after which it is subsequently reused The mold coating as described above is distinguished from the coating processes after the mold, in which the filling resin is molded before the coating is introduced into the mold, and from conventional decoration operations, in which the filling resin is molded and cured in the mold, then released from the mold and decorated with a coating powder or other finish.The mold coating also differs from the process of mold coating, in which matching molds are used and the coating and filling resin are cured in a closed molding environment under heat and pressure. There are a number of disadvantages associated with the use of liquid gel coatings during mold coating. For example, liquid gel coatings are difficult to apply uniformly to the surface of the mold and excess d? spraying must be collected and disposed of as hazardous waste. Consequently, the transfer efficiency of liquid gel coatings is extremely low (i.e., about 38%). The liquid gel coatings also contain alarmingly high levels d? Volatile organic solvents or liquid crosslinking monomers, such as liquid styrene monomers, which tend to evaporate when sprayed on the mold, changing it? This way the coating formulation, creating bubbles, unwanted porosity, and other irregularities in the surface coating, and generating VOC to unsafe levels, making it necessary to contain and collect the vapor of the volatile ingredients. Also, this way of operation results in prolonged cycle times since the gel coating must be allowed to harden for several hours before the application of the filling resin. Finally, the resulting surface coating, despite being very thick, is insufficiently resistant to scraping, cracking, impact, light, heat, humidity, salinity, weathering and solvents. In view of the above disadvantages, recent emphasis has been placed on finding an appropriate replacement for liquid gel coatings. Liquid coatings carried in water and elevated in solids have been treated, but fail to deliver the necessary performance. Thermosetting coating powders have also been proposed. Coating powders have a number of advantages over liquid gel coatings. For example, "they are essentially free of volatile organic solvents and, as a result, they give off little if any, VOC to the environment when they are cured." Furthermore, coating powders improve work hygiene, since they are in solid form. They are free flowing, dry, and have no dirty liquids associated with them to adhere to workers' clothes and coating equipment.They are relatively non-toxic and in the event of a spill they are easily swept without requiring special cleaning or supplies Finally, the sprayed powder can be recycled during the coating operation and recombined with the original powder feed, leading to very high transfer efficiencies (ie almost 100%) and minimum generation of waste. , thermosetting coating powders are not without problems, Traditionally, they have not been suitable for application to sensitive substrates heat, including plastic molds, such as the unsaturated polyester molds normally used in the manufacture of the molded articles described above, because of the rather high temperatures required for melt flow and powder curing. Because these molds are rather expensive and must be reused again and again, the thermal damage caused by curing temperatures above their softening point - or plastic deformation temperature can not be tolerated. While a number of thermosetting lower temperature curing coating powders based on unsaturated polyester resins have been proposed for in-mold coating purposes, they have also suffered from significant disadvantages, such as an inability to cure sufficiently on the surface at an open air molding process, making said powders useful only in the closed molding environment, or an inability to resist block or sintering at room temperature, making said powders physically unstable and virtually unusable after prolonged storage . The U.S. Patent A. 4,316,869 (Van Gasse) teaches a method for in-mold lining of molded articles, particularly glass fiber reinforced boat hulls, with thermosetting liner poles. Specifically described are powdered unsaturated polyester resin formulations containing an unsaturated polyester resin, a prepolymer d? diallyl ester of copolymerizable crosslinking, a curing initiator, together with other common additives. Also required is a "boiling" copolymerizable crosslinking monomer, in particular, di- or t-ringyl-functional monomers, such as triallyl uranyl and triallyl isocyanurate. However, there are disadvantages to using monomers For example, these monomers are typically liquid or waxy solids (low melting) at room temperature that have only limited use in coating powders.When ST employ beyond trace quantities, they tend to dramatically reduce the transition temperature of glass (Tg) of the formulation, causing the powders to block out sintering during storage and making them virtually impossible to measure or spray during commercial coating operations.The conversion of these materials into superior melting solids is rather costly and takes weather.

SUMMARY OF THE INVENTION Therefore, an object of this invention is to provide means for manufacturing molded articles formed from thermosetting resins, with or without f reinforcement, which avoids the above disadvantages. More particularly, it is an object of this invention to provide methods for in-mold coating the surface of molded articles formed from thermosetting resins during their manufacture with low temperature curing thermosetting coating powders, molded articles having surface coatings formed in this manner, therein, and low temperature curing thermosetting coating powders adapted for use in such mold coating methods, which avoid the above disadvantages. In accordance with one aspect of this invention, there is provided a method for in-mold coating the timeless surface of a molded article formed from thermosetting resins, with or without glass f reinforcement, on a thermally sensitive female mold surface (i.e. , plastic) without damaging the mold, using an unsaturated, thermosetting polyester powder coating of low temperature curing, which methods comprise: a) providing one of the compositions of low temperature tempering, thermosetting, unsaturated polyester powder coating compositions descr later; b) applying the coating powder, which is converted to the outer surface of the molded article, towards the surface of the mold, preferably while the mold surface is sufficiently hot to cause the powder particles to melt and flow and disperse on the molding surface and form a substantially continuous film at least along the mold interface; c) heating the powder coated surface of the mold to melt and render any solid powder particles and cause the resulting monolithic coating film to cure, preferably to completion: d) apply a compatible liquid thermosetting resin, with or without fglass reinforcement, which constitutes the volume of the molded article, towards the cured coating powder film and allowing the curing of the filling resin to progress sufficiently until the powder coating and the filling resin are integral; and, e) removing the molded article from the mold as the finished coated article. In the aforementioned method, the coating powder application and the curing of steps b) and c) are preferably carried out in an open air environment, i.e. while the mold is open and exposed to conditions environmental In accordance with another aspect of this invention, thermosetting coating powders are provided adapted for the mold coating methods, whose ST- powders. they melt, are extrudable, storage stable, easily fluidizable, and not only curable in an open air environment, but also at temperatures low enough to not cause damage to plastic molds, and are also capable of providing a surface coating which is exceptionally smooth, uniform, lustrous and attractive in appearance with little or no surface porosity, resistant to. scraping, impact, cracking, staining, light, heat, humidity, salinity, weathering and solvents, and one that forms a very strong bond with the thermosetting resin, where the powders essentially consist of a reactive film forming mixture in the form of particles of: a) an ethylenically unsaturated polyester resin; b) an ethylenically unsaturated, crosslinking, copolymerizable prepolymer; c) a thermal initiator; d) an optional curing catalyst; and e) an agent d? mold release, provided that: i) the particulate mixture is essentially free of any ethylenically unsaturated, crosslinking, copolymerizable monomers; and preferably with the additional condition that: ii) either resin d? The unsaturated polyester contains at least one reactive hydrogen atom, or the particulate mixture further consists essentially of a photoinitiator along the thermal initiator, or both. In the above mold coating method, if the coating powder includes a photoinitiator, before or after the heating step c), the coating film is exposed to sufficient ultraviolet radiation or ionization to effect radiation curing as required. length of the surface exposed to air. A preferred first mold coating powder useful in this invention consists essentially of a particulate mixture of a) an unsaturated polyester resin containing active hydrogen atoms obtained by the condensation of an acid. ethylenically unsaturated dicarboxylic acid (or anhydride), e.g., maleic anhydride or fumaric acid, and a diol possessing active hydrogen atoms, e.g., 1-cyclohexa.no dimethanol, to reduce the inhibition of air e- cured to the exposed surface and improve out-of-behavior flow at low temperatures, together with lower amounts of aromatic dicarboxylic acid (or 'anhydride') dry) and aromatic diols, e.g., a combination of phthalic anhydride and hydrogenated bisphenol A, respectively, to raise the Tg of the resin so that the pulverized mixture remains physically stable and solid at room temperature, together with b) a p-repolymer of difunctional allyl ester, crosslinking, v.gr, isodialyl phthalate, b) a thermal peroxide initiator, e.g., peroxy ketal, d) an oxidation reduction catalyst, v .gr., a cobalt salt, and e) a mold release agent, and the usual additives. A second preferred powder coating powder useful in this invention consists essentially of a mixture of particles of a) an unsaturated polyether resin containing unsaturation of maleate "or fumarate, b) a difunctional vinyl ether urethane prepolymer crosslinking, c) a peroxide thermal initiator, v.gr ,, a peroxy ketal, d) a oxidation reduction catalyst v.gr ,, cobalt salt, e) a mold release agent, and f) a photoinitiator, v, A benzyl ketal, acyl phosphine or arylketone, along with the usual additives, is provided in yet another aspect of this invention, molded articles, with or without fiber reinforcement, having surface coatings formed thereon by means of which are provided. above-mentioned mold-coating methods The various aspects, features and advantages of this invention will become more apparent from the following description and appended claims.

Detailed Description of the Preferred Modes Through this specification, all parts and percentages specified therein are by weight unless otherwise stated, likewise, in the following description of the coating powders used to form the outer skin of the molded product, the component a) (the 'unsaturated polyester resin) and the component b) (the unsaturated, crosslinking, copolymerizable prepolymer) are considered here as the "resin" and equal to 100 parts. of gold components are calculated as parts in relation to 100 parts of the resin (abbreviated "phr").

Mold Coating Powders Coating powders useful in practice d? This invention is resin formulations of "unsaturated polyester, thermosettable, pulverized, curing at low temperature adapted to be applied to a mold surface and form an external skin on a resinous body molded therein without damaging the mold. The coating consists essentially of a reactive film-forming particulate mixture of an ethylenically unsaturated polyester resin, an ethylenically unsaturated crosslinking prepolymer, a thermal initiator, optional curing catalyst, and a mold release aid, with the proviso that The particulate mixture is essentially free of any ethylenically unsaturated crosslinking monomers In order to achieve a sufficient surface cure in an open air mold environment as contemplated in this invention, the preferred powders are further characterized that already be the unsaturated polyester resin possesses an ato active hydrogen, or the particulate mixture further consists essentially of a photoinitiator along the thermal initiator, or both. It is particularly important that any unsaturated polyoster coating powder employed in an open-faced mold coating process be able to achieve complete cure along the inner surface of the coating exposed to air, since this prevents the resin from Fill blood fluid through the powder coating film and undo the appearance of the outer surface finish. The unsaturated polyester resins useful in practice d? this invention can be obtained in a conventional manner, such as by condensation of one or more di- or polyfunctional carboxylic acids or their anhydrides, d? Preference is given to dicarboxylic acids or their anhydrides, with one or more di- or polyfunctional alcohols, preferably dihydric alcohols. The ethylenic unsaturation is usually supplied by the acid, even though it is possible to supply it in its place through the polyol. The unsaturation can be provided in the polymer structure or at the end of the chain. If provided in the structure, the di- and polyfunctional ethylenically unsaturated acids or their anhydrides useful for this purpose include maleic anhydride, fumaric acid, itaconic anhydride, tetrahydphthalic anhydride, nadic anhydride, dimethyl methacrylic acid, etc. Maleic anhydride, fumaric acid or mixtures thereof are generally preferred due to economic considerations. It should be understood that whether or not anhydrides are listed, any of these forms are contemplated for use herein, If the unsaturation is supplied at the end of the chain, monofunctional, ethylenically unsaturated carboxylic acids (or their esters) are used, for example, acrylic acid, methacrylic acid, etc. Frequently, smaller amounts of di- and polyfunctional, saturated, aliphatic and aromatic carboxylic acids or their anhydrides are used in conjunction with the ethylenically unsaturated acids to reduce the density of the ethyl ionic unsaturation and provide the desired chemical and mechanical properties. of appropriate saturated aliphatic and aromatic polyfunctional acids (or anhydrides thereof) used to make especially the properties of the resin (eg, raising the Tg of the resin) include adipic acid, succinic acid, sebacic acid, phthalic anhydride , isophthalic acid, terephthalic acid, dimethylterephthalate, dimethylisophthalate, tetrahydrophthalic acid, hexahydrophthalic acid, dicyclohexane dicarboxylic acid, dodecane dicarboxylic acid. - le ¬ trimellitic acid, pyro elitic anhydride. etc., As described above, to allow surface curing of the exposed surface of the coating film in an open air molding environment, it is desirable that the polyester resin contain an active hydrogen atom in its structure . The term "active hydrogen" used herein means an atom and hydrogen that is easily abstracted by free radicals and participates in the curing reaction. Active hydrogen atoms are typically supplied by the polyol, even though it may instead come from acids containing active hydrogen used in conjunction with the unsaturated acid. Examples of di- or polyfunctional alcohols useful herein containing active hydrogen atoms include those with allylic, benzyl, tertiary alkyl or cyclohexyl hydrogen atoms. These active hydrogen atoms are readily absorbed during free-radical-induced curing and form corresponding free allylic, benzylic, cyclohexyl and alkyl-free radicals, all of which promote curing on the exposed surface; While not wishing to be bound by theory, it is believed that the inclusion of an active hydrogen-containing compound in the unsaturated polyster molecule allows the generation of free radicals that. They have greater stability and are less susceptible to allow deactivation during contact with atmospheric oxygen. Examples d? suitable di- or polyfunctional alcohols possessing active hydrogens include alcohols having: an allylic hydrogen, such as trimethylolpropane monoallyl ether, trimethylolpropane diallyl ether, vinylcyclohexanediol, etc :, a benzyl hydrogen, such as benzene dimethanol, etc.; a tertiary alkyl hydrogen, such as methylpropanediol, butylethylpropanediol, etc .; and - a cyclohexyl hydrogen, such as cyclohexane dimethanol, cyclohexane diol, etc. As mentioned above, it is also possible to supply the active hydrogen through the carboxylic acid. Examples of suitable di- or polyfunctional carboxylic acids with active hydrogens include carboxylic acids having; a hydrogen, of malonyl, such as malonic acid, etc .; or an allylic hydrogen, such as nadic anhydride, tetrahydphthalic anhydride, dimer acid, etc. Frequently, the polyols without active hydrogens are used in the condensation reaction in conjunction with a substantial proportion of polyols which - they contain active hydrogen to provide the desired chemical and mechanical properties. Typically, between about 10 and 100 mole%, and. preferably between about 50 and 100 mol%, of the hydroxyl functionality relative to the total hydroxyl functionality of monomers used to form the unsaturated polyether resin A) is supplied by polyol monomers containing active hydrogen, the remainder being polyols containing non-active hydrogen. Examples of suitable di- or polyfunctional alcohols do not contain active hydrogens used to prepare especially the properties of the resin (e.g., to raise the Tg of the resin) include ethylene glycol, ethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol. , butanediol, dodecanediol, hydrogenated bisphenol A, adducts of bisphenol A / propylene oxide, glycerol, trimethylolpropane, trimethylolethane, etc., Whether the polyester is functional acid or functionalized hydroxyl depends on the -COOH / -OH ratio of the mixture of monomer. while 'these saturated functionalities generally do not participate in the curing reaction that continues mainly through the unsaturated groups, frequently- they are used to achieve the chemical properties or. desired mechanical - id - in the final polymer. If the polyester-unsaturated acid is functional acid, the acid number is usually about 1 to 80. If the unsaturated polyester is functional hydroxyl, the hydroxyl number is usually from about 5 to 100. The unsaturated polyester resin can be formulated to be crystalline (ie, semi-crystalline), or amorphous. Crystalline resins or mixtures of crystalline and amorphous resins are desirable to form powder coatings with low melt viscosities and good flow out of the behavior at low temperatures. It is well known in the art that certain alcohol and acid monomers impart crystallinity to unsaturated polyesters. For example, symmetrically substituted linear monomers or cyclic monomers or their mixtures "are generally used to form crystalline polyesters Examples of suitable diols known to promote crystallinity include ethylene glycol, butanediol, hexanediol, and cyclohexane dimethanol. of suitable dicarboxylic acids known to do the same include tarephthalic acid, adipic acid, dodecanedicarboxylic acid, and cyclohexanedicarboxylic acid, more desirably, unsaturated polyesters suitable for the practice of this invention are solid materials substantially at more than room temperature , so that they can easily be formulated into coating powders that will not be blocked or sintered during environmental storage On the other hand, unsaturated polyols have sufficiently low melting temperatures and melt viscosities at such temperatures to permit It is noted that the coating powders formulated therefrom melt, flow and easily disperse on the. Full mold surface below the mold deformation temperature. It should be understood that what determines the above properties of the coating powders is generally the unsaturated polyester resin component used therein, and this comprises the main portion of the resin. The unsaturated polyester resins, therefore, preferably have a molecular weight in the range of about 400 to 10,000 and, preferably, 1,000 to about 4,500, a sufficiently high glass transition temperature (Tg) to prevent the sintering at room temperature to about 32-38 ° C, preferably a Tg of about 41 to 65 ° C, and more preferably, about 41 to 49 ° C, and a sufficiently low melt viscosity to allow the powder after melting, to completely wet the Mold surface at the desired mold temperature and form a smooth film thereon with virtually no surface porosity, preferably a melt viscosity at 175SC less than about 5,000 centipoise, and more preferably between about 3.750 to 4.750 centipoise. The degree of unsaturation, preferably unsaturation of maleate or fumarate, normally present in said polyester resins is preferably in the range of about 2 to 20% by weight, of the polyester resin, and more preferably, about 4. to 10% by weight. The polyether unsaturated resin is mixed with an ethylenically unsaturated prepolymer or oligomer, crosslinking, copolymerized which, after curing, reacts with linear polyester chains to crosslink them and thus impart thermosetting properties to the coating. in the practice of this invention, preference is given to difunctional compounds which are solid at room temperature. These solid resins generally include prepolymers containing vinyl ether, vinyl ester, allyl ether, allyl ester, methoxylate or methacrylate groups in the chain ends.

Examples of suitable prepolymers include allyl esters, such as diallyl phthalates, isodialyl phthalates and p-diallyl phthalates, which are obtained by the reaction product of allyl alcohol and phthalic anhydride; allyl esters, such as those obtained by reaction of allyl propoxylate and hydrogenated methylene diisocyanate, etc .; vinyl ethers, such as amyl ether urethanes, including those obtained by the reaction of hydroxybutyl vinyl ether with either diisocyanates, isocyanate-terminated alcohol adducts, or isocyanurates, etc .; and, methacrylates or acrylates, "such as urethanes, methacrylates or acrylates, including those formed by the reaction of -hydroxyethyl or hydroxypropyl methacrylate or acrylate with diisocyanates, etc. Crosslinking prepolymers, such as unsaturated polyesters, can be formulated to have a crystalline or amorphous microstructure, This will depend on the choice of monomers used in the formation reaction, as is known in the art, and the desired outward flow behavior and the final coating properties, will be observed by those skilled in the art that the amount of unsaturated prepolymer in relation to the unsaturated polyester resin will depend on the choice of the materials used. Usually, these materials are used in the amount necessary to allow the crosslinking to proceed to completion. this results in less than about 25% by weight of the resin q The crosslinking prepolymer is comprised. A thermal initiator is used to generate pounds radicals and to induce crosslinking of the polyester resin to a thermoset state. The thermal initiators useful herein are desirably solid at room temperature and are preferably selected from peroxide and azo compounds. Examples of suitable peroxide initiators include peroxy ketals, such as 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyanohexane, diacyl peroxides, such as benzoyl peroxide, peroxy esters, dialkyl peroxides, peroxides ketone, etc., with the peroxy ketals being preferred. It is further desired that the activity of the initiator be such as to allow curing to proceed below the mold deformation temperature, preferably less than about 163aC, while not causing substantial cure in the extruder during conventional melt processing. Therefore, it is particularly desired to employ thermal initiators having an average lifetime of one sheet between about 41 and 57BC. The amount of thermal initiator employed in the coating powder composition of the present invention typically varies between about 0.1 and 10 phr, and preferably between about 1 and 5 phr. Conventional photoinitiators can also be used in conjunction with thermal initiators for photoactivated curing (ie, radiation). As described above, the thermal curing of the powder composition can be aided along the exposed surface by compounds that form free radicals under photolytic conditions, v.gr-, during exposure to sufficient ultraviolet radiation or ionization, v.gr , electronic beam., radiation. This is especially important with powders based on unsaturated polyesters that do not contain active hydrogen atoms. As with thermal initiators, photoinitiators should be solid compounds at room temperature. Of course, if they are liquids, as with any of the other materials used in the powders, they can be converted to solids by absorption into inert filler before use, as is well known in the art. However, liquids should be avoided whenever possible. Examples of suitable photoinitiators include benzoin ethers, benzyl ketals, such as benzyl dimethyl ketal, acyl phosphines, such as 2,4,6-trimethoxybenzoyl diphenylphosphine oxide, and aryl ketones, such as l-hydroxycyclohexyl phenyl ketone, etc. Photoinitiators, if included, are generally employed in a sufficient amount to allow curing by radiation along the surface of the coating film exposed to air, Typically, this translates to a scale of about 0.1 to 10 phr, and preferably between about 1 and 5 phr. Accelerators or catalysts, particularly oxidation reduction catalysts, can also be employed in the de-dusting powder to induce the generation of free radicals and allow the crosslinking reactions to proceed at faster rates. With reduction catalysts "by oxidation, the transition metal compounds based on a fatty acid or oil can be used. Examples of suitable metals include cobalt, manganese, lead, copper and vanadium. cobalt of monocarboxylic acids, ie, fatty acids), for example, cobalt octoate, cobalt neodecanoate, cobalt naphthalate, and cobalt octadecanoate are most preferred, while curing, on the surface of the coating, even the radicals Free formed at the sites of active hydrogen tend to react- with tmospheric oxygen to form hydroperoxides ... that is, inactivated peroxide initiators, that plug the free radicals and stop the curing reaction, however, the hydroperoxides formed from this way, due to its location, they decompose easily in the presence of the cobalt salts to restart the curing of free radical, p thereby allowing the curing to proceed to completion on the surface, oxidation reduction catalysts are generally employed in the coating powder in amounts of less than about 1.0 phr, and preferably in. the slat between about 0.1 and 0.5 phr. Also contained in the coating powders of this invention are internal mold release agents or lubricants. These lubricating materials promote the division of the mold after curing. Examples of suitable mold release agents include metal soaps of fatty acids, such as zinc stearate, copolymers of organophosphate esters, and modified fatty acids, etc. The release agents of. The molds are used in an amount sufficient to allow release of the cured coating from the mold after the molded article is completed. The release agents are generally employed in the coating powder of this invention on a scale of about 0.1 and 10 phr, and preferably on a scale between approximately 2 and 5 phr. Comp described above, the unsaturated polyester powder coating powders of this invention are virtually free of any copolymerizable ethylenically unsaturated crosslinking onomers, such as those previously mentioned herein and further described in US Pat. , UA, 4,316,869 the teaching of which is hereby incorporated by reference in its entirety, consequently, - the blocking resistance of these powders is improved substantially. allowing the application by electrostatic spraying of the powders on the surface of the mold and the formation of high quality coatings with minimal surface imperfections?) It should be understood that the coating powders of this invention may also contain the other usual additives. For example, the coating powders may include conventional pigments and / or fillers, typically in an amount of up to 120 phr, to impart the desired color and opacity to the coating film, although transparent coatings are also possible (i.e. - not pigmented). The appropriate pigments. they include inorganic pigments such as co or titanium dioxide, and organic pigments, such as carbon black, etc. Suitable fillers include calcium carbonate, barium sulfate, wollastonite, mica, ceramic clay, diatomaceous earth, boric acid, low molecular weight nylon, etc. Other common additives, such as luster control gene, flow or leveling agents, dry flow additives, anti-cracking or degassing agents, agents d? texturization, light stabilizers, ultraviolet absorbers, antioxidants, etc., typically in a total amount of up to about 15 phr, may also be included. Appropriate luster control agents include polyethylene waxes, oxidized polyethylene, pnjjamides, teflons, polyamides, etc.: flow control agents include acrylic resins, silicone resins, etc.; Dry flow additives include fumed silica, alumina oxide, 'etc; anti-cracking or degassing agents include benzoin, benzoin derivatives, low molecular weight phenoxy and phthalate plasticizers, etc .; texturing agents include organoilieag clays, cross-linked rubber particles.- multiple curing agents, etc .; the light stabilizers include hindered amines, etc. The appropriate Uv absorbers include benzotriazoles, etc .; Antioxidants include organophosphites, hindered phenolics, etc. The melting temperatures and curing temperatures of the above powders will vary somewhat depending on the various ingredients employed. However, it is particularly important that the coating powders possess the ability to flow by melting and coalesce easily to a connate or no surface porosity at temperatures and times that are safe for plastic molds, while at At the same time they are physically stable under environmental storage conditions and are chemically non-reactive during conventional melt processing. Accordingly, the reagent powders useful in the practice of this invention are formulated to be free-flowing solid particles, dried at room temperature and do not exhibit sintering at temperatures of at least up to 32 ° C, preferably up to about 43SC furthermore, the coating powders desirably have a melting temperature (ie, flux temperature) of less than about 12lsC, preferably in the range of about 49 to 71sc and a melting temperature of less than about 177BC, preferably on the scale of approximately 121 to 149SC, temperatures consistent with the application of coating powder compositions to plastic molds. Of course, the curing depends on the time "as well as it depends on the temperature, however," a complete cure at the above temperatures can be achieved within a commercially reasonable time, for example, in about 30 minutes or less, d? preference in about 15 minutes or less. Preferred powder coatings of this invention can effect a complete cure between about 121-149SC in about 5 minutes or less, which is safe for more heat sensitive applications. A "complete cure" is a degree of cure reached at which additional time at elevated temperature will not improve the properties of the coating once it is cooled to ambient temperatures For heat-reflecting reverse powders, the level of cure can be measured by the solvent resistance of the backing Typically, a fully cured coating will withstand up to about 50 double rubs using methyl ethyl ketone (MEK) solvent without rubbing through the coated substrate A double rub is a rubbing from one side to the other a cloth saturated with solvent using pressure applied with the normal hand.

Coating Powder Preparation The coating powders of this invention are prepared in the usual manner. First, an intimate mixture is formed by dry mixing of all the ingredients of the formulation together in a mixer. A dry mix is then melt-blended in a mixing extruder with heating above-1 point d? Fusion of the resin and other ingredients, when necessary, so that the extrusion is a complete and homogeneous mixture Extrusion is preferably carried out at between approximately 82 and 12 ° C to minimize any curing. and gelation in the extruder The gaseous or supercritical fluid, v.gr .. C02, can be charged to the extruder to reduce extrusion temperatures.The extruded composition cools rapidly and solidifies and then breaks into chips. , the chips are milled in a mill with cooling and, as necessary, the particles are sized and sized according to the size The average particle size desired for electrostatic application is generally between about 20 and 60 micrometers.

Liquid Filling Resins Liquid Filling Resins d? thermosetting. which constitute the volume of the finished article, useful in the practice of this invention are well known in the art. The particular filler resin must have a chemical that is compatible with the coating powder to avoid adhesion problems in the molding. These problems manifest blistered bubbles between the filler resin and the coating of the finished part, or as insufficient adhesion between the filler resin and the backfill. Therefore, it is particularly advantageous to employ liquid filler resin formulations of p the unsaturated ester to coincide with the chemistry of the coating powders. These filler resins typically consist of unsaturated polyester resins and re-monomers, eg styrene together with the usual additives. such thermal co-ordinators, hardening accelerators or catalysts, retarders, glazing agents and fillers Molds The present invention contemplates the use of a female mold of the type commonly used in the manufacture of molded articles from resins of thermosetting, with or without fiberglass reinforcement. More frequently, heat-sensitive plastic molds, v.gr-, unsaturated polyester molds, ST use, which have an internal surface in the configuration of the article to be molded. The molds also usually contain conductive pigments, e.g., carbon black, mixed therein which make their surfaces sufficiently conductive for coating the ctostatic. Since these molds are rather expensive and ST is required to be used again and again, the coating powder must be capable of melt flow and be cured at temperatures below the softening point n plastic deformation temperature of the molds . T.? plastic deformation temperature of said molds is typically between approximately 1.90 and 232SC. The significant thermal damage that occurs to the surface of the mold during the mold coating (cracking, cracking, blistering and warping) can not be tolerated, since this not only will it adversely affect the final configuration of the finished item, but it will also affect the overall quality of the surface finish.

Mold Coating Methods and Products The method of this invention for forming a mold coated article into a mold starts by providing one of the thermosetting unsaturated polyester coating powder compositions described above and a plastic female mold having a surface imparting configuration defined by the inner wall of the mold. In an open atmosphere the particles of the unsaturated polyester formulation are applied to the surface of the mold, and then heated to melt the particles, after which they flow and disperse easily forming a substantially continuous and preferably completely continuous film that coats the mold surface. Preferably, the mold surface is pre-heated prior to the deposition of the unsaturated polyester particles, to cause the powder particles, as they strike the hot mold, to melt immediately, flow and moisten and coalesce towards a substantially continuous coating film which at least rotates the mold interface The mold can be treated with a mold release agent and / or a conductive wash prior to application of the powder, if desired. the initial preheating step is usually carried out in a preheating station which houses banks of infrared (IR) lamps of high intensity, short wave, medium or long, directed on the surface of the mold for surface heating only .- "even when conventional convention ovens or XR ovens and combination convection can be used. The ST wavelength TR lamps generally prefer. The final temperature of the mold surface reached during the pre-heating phase should be sufficiently high (but still lower than the mold deformation temperature), so that by the time the mold is transferred from the preheating station At the powder application area, the surface temperature does not fall below the temperature necessary to melt the powder particles, at least at the interface of the mold. The time and temperature of the preheating will vary somewhat depending on the coating powders employed. For the aforementioned powders, the surface temperature of the mold as it leaves the pre-catalyst station is preferably approximately 163eC, because the Room temperature is usually around 21 to 27aC, the surface temperature of the mold will rapidly drop to a value much lower than 163QC by the time the mold reaches the powder coating area which is preferably a short distance. However, as the previously heated mold enters the powder coating station, the surface temperature of the mold must still be above the temperature necessary to cause the powder particles, as they impinge on the hot mold surface, melt immediately flow and moisten the entire mold surface For powders previously In this case, the surface temperature of the mold immediately before the powder coating is preferably about 93 to 121sp. This preheating is advantageous due to a number of reasons. For example, preheating improves the initial attraction of the powder to the surface of the mold, reduces the time needed to cure the powders, results in a more uni-shaped durability, and more importantly allows the development d? the coating films with the desired softness (ie, no scratches) and luster (i.e. a gloss value of 609 of about 85 or greater) with minimal surface porosity, While preheating is preferred, the coating powders may applied to a mold surface at room temperature followed, by subsequent melting and curing, even though generally less attractive films are produced. After leaving the pre-heating station, the mold is preferably moved to a powder spray booth located a short distance from the preheating station, where the powder-coating particles are applied to the surface of the powder. hot mold by electrostatic spraying, while the application by electrostatic means is preferred, any other conventional powder coating process can be used to-, apply the dust particles. The powder spray booth typically houses banks of corona discharge or tri-boiler guns and a dust recovery system. The successive layers are applied bluntly necessary to obtain thicker films- The pejículas that have a thickness after the curing of around 0.13 to 0.76 millimeters are the most frequently used, 'It must be understood that even when it is important to have the powders that affect on the mold surface to completely melt or coalesce into a coating that coats the mold to derive the full benefit of the aforementioned coating powders, due to the cooling of the environment and the cooling effect of the powder coating itself, the particles of powder applied on them. Interface powders may remain unmelted or partially melted until final curing. After powder application, the powder coated mold is then moved to a powder curing station located preferably a short distance from the powder spray booth. The powder curing station can be one and the same as the station d? preheating dust. In the powder curing station, the mold surface is again heated, preferably using the TP lamps as described in the foregoing to a temperature sufficient to melt and flow any non-molten particles of powder and cure the film. resulting monolithic coating on the mold surface, preferably until finished. While it is possible to keep the coating film in a partially cured state until the filler resin is added and then cure both resins simultaneously until an alkaline cure, it is preferred to completely cure the unsaturated polyester film before adding the resin rosin to Prevent the filling resin from bleeding into the powder coating film. Therefore, in the powder curing station, the powder-coated mold surface is heated to a temperature equal to or higher than the coating powder cure temperature and lower than the mold deformation temperature and maintained at that temperature. level until the powder is completely cured, thereby forming a thermosetting film hardened onto the mold surface having an external surface (defined herein as the surface against the mold surface) and a surface internal opposite exposed to an open air environment m? The time and temperature of the final curing will vary somewhat depending on the coating powder used and the conditions of use. However, for the aforementioned coating powders, the mold surface preferably is heated to a temperature between about 149 and 177aC for about 2 to 5 minutes to effect complete curing. If a photoinitiator is used in the coating powder, the coating film is further exposed for a sufficient time to radiation, such as ultraviolet or electron beam radiation, to allow radiation curing of the exposed internal surface of the coating film. . Ultraviolet radiation is generally preferred. Radiation curing, if employed, is usually carried out after curing powder in a radiation curing station preferably placed at a short distance from the powder curing station. Ultraviolet radiation is typically delivered by means of mercury lamps of medium pressure or of adulterated mercury vapor, such as Fusion H-, D- and / or lamps v, for a sufficient time, v.gr .., between approximately 1 millisecond and 10 seconds, typically less than about 3 seconds, to activate the photoinitiator and initiate photopolymerization on the inner surface. Radiation curing can also be carried out immediately after dusting., as long as the powder particles applied have completely melted on the surface of the mold. In addition to the method described above, after the powder coating film has been cured, the mold is transferred to a molding station, wherein the inner surface of the cured coating film is contacted at the exposed interface with a liquid filling resin. The liquid filling resin can be applied by means of spatulas, brushes. rollers or sprinklers. The pertinent techniques - known by the names of manual laying and. sprayed The technique of manual laying involves placing a esters d? glass or other reinforcement materials in the mold and saturate the reinforcement material with the filling resin. In the spraying technique, a layer of loose glass fibers and filler resin are sprayed into the mold. The successive layers are added and cured as necessary to form the molded article to the desired final thickness. This volume layer can also be formed by a technique known as resin transfer molding wherein the dry reinforcement materials are placed in a mold cavity defined by one or more mold surfaces and the liquid fill resin is injected. then into the cavity to form the molded product, sometimes under vacuum. After the curing of the filling resin layer has advanced sufficiently and the coating film and the filling resin are integral through its interface, the shaped article can be separated from the mold. Before or after the removal, it is also possible to apply other layers consisting of materials of a different kind, for example, fiber reinforced cement, foamed polymer, or a combination of both, on the filling resin layer. When the molded product is separated from the mold, the coating powder film defines the external surface of the molded body with complete fidelity to the mold configuration. In summary, this invention provides a method for in-mold coating molded articles formed from thermosetting resins. with or without fiber reinforcement, with thermosetting coating powders in an open atmosphere, surprisingly without causing thermal damage to the molds sensitive to heat, cracking, blistering, warping, etc. during melting and rhyming -or without producing coatings lower surfaces that lack the desired non-porosity, smoothness, luster, beauty, luminosity, uniformity, adhesion between layers, and / or resistance to scraping, light cracking impact, heat, humidity, salinity, weathering and solvents. ' What makes this in-mold coating method possible is that the thermosetting coating powders used are uniquely formulated to melt, flow and rotate to a uniform film and achieve complete curing, even along the surface exposed to air. , in the molds at extraordinarily low temperatures and / or fast speeds, while still stable to storage and extrudable by melting.

The invention will now be described in more detail through specific examples.

Example 1 Preparation of Unsaturated Polyester Resin that Contains Active Hydrogen Atoms This is an example of a found polyester resin in.satur.adp that is especially useful e? the practice of this invention. 0.85 moles (122.4 g) of 1,4-cyclohexane di ethanol was charged to a 0.5 liter resin fret equipped with a partial condenser, total condenser, stirrer, nitrogen inlet and temperature controller. While a stream of nitrogen is introduced at the rate of -25-30 mL / min and stirred, the temperature rose to 125 ° C. Then, 0.6 mol (88.8 g) of phthalic anhydride, 0-5 mol (58 g) of fumaric acid, 0-5 mol .. (. 3g g). Of bisphenol? .hydrogenated, and '50 ppm of 4-methoxyphenol (antioxidant) to the fret. While still stirring and spraying with nitrogen, the temperature rose slowly to 180 ° C while the esterification water was collected. When 85-90% of the theoretical distillate had been collected, the nitrogen purge rate was increased to 200 ml / min. The viscosity and the acid value of the resin were checked periodically to u? the desired values were obtained. The amorphous resin was then discharged to a tray, ST cooled and ground to scale. Multiple tests were performed and the resins had properties within the scales provided in the table below.

Properties Example 1 Glass transition temperature (Tg) 42-47sC "Melting Point 52-57aC Acid Number (mg KOH / g resin) 47 Viscosity ICI @ 1752C 3750-4750 cps Molecular Weight (Mn) per GPC 1700 -1850 Example 2 - -. Preparation of Coating Powders in Unsaturated Polyester Mold The following ingredients were mixed together in a certain manner and amounts to form three different mold coating powder formulations (A, B, C) of this invention.

Ingredients Parts in ABC Weight DRY MIXTURE IN MIXER UNTIL HOMOGENEOUS Polyster Unsaturated (from Example 1) 95 Pioester 277-FLV (Unsaturated Polyester) 1 95 Isodiallyl Phthalate (Diallyl Ester Prepolymer) 5 5 Lupersol 231XL (Peroxide Initiator) 2 4.Í 4.5 Uralac XP3125 (Unsaturated Polyol) 3 80 Uralac ZW-3307 (Divinyl Ether Prepolymer) 4 20 Surfonyl 104-S (Flow Agent) 5 1 1 Modaflo 2000 (Acrylic Flow Agent) 6 1 1 ' 1 Moldwiz P66 (Release Agent) 7 3 3 3 Cobalt Neodecanoate (Catalyzed oxidation reduction) '0.1 0.1 0.2 TR 93 TiQ2 (Pigment) 9 20 20 20 R-8098 Red (Iron Oxide Pigment) 10 0.01 0.01 0.01 Raven Black 22 { Pigment of A B C Carbon Black) 11 0. 014 0. 014 0. 014 FUSING MIXTURE IN SCREW EXTRUDER DOUBLE TO 82 SC - EXTRUDED COLD AND BREAKING IN CHIPS LOADING CHIPS AND 0. 2% AN ALUMINUM OXIDE WEIGHT C1Z MILL BRINKMANN MOLER UNTIL POWDER AND SHREDDING MESH -140 Fitted Notes of the Table ^ ioester 277-FLV is an unsaturated polyester resin containing CHD and having a Tg of 36fiC, a melt viscosity of 8,000 centipoise at 175SC and an acid number of 12, sold by Pioneer Plastics. 2Lupersol 231XL is a free radical initiator, peroxy ketal, based on l-l-bis (t-butylperoxy)) 3, 3, 5, -trimetilcelohexane, sold by Elf Atochem. 3Uralac XP3125 is an unsaturated polyester resin having a Tg of 51SC and an acid number of 10 max, sold by DSM Resins. Uralac ZW-3307 is a urethane prepolymer terminated in crystalline divinyl ether having a Tm of '90 to 110aC, sold by DSM Resins. 5Surfonyl 104-S is an acetylenic diol flow agent, sold by Air Products. dModaflow 2000 is an acrylic copolymer flow agent, sold by Mozel Inc. 7Moldwiz P-66 is a mold release agent containing copolymers of organophosphate esters and modified fatty acids, sold by Axel Plastics. . 8 Cobalt Niodecanoate is a cobalt salt, sold by OMG Americas. 9TR 93 is a titanium dioxide pigment, sold by TTíoxide Americas. LúR-8098 Red is an iron oxide pigment, sold by Hittaker, Clark and Daniels. "Raven Black 22 is a carbon black pigment sold by Colu bian Chemicals." Aluminum Oxide C is a fuming alumina dry flow additive sold by Sullivan Associates.

Example 3 Coating method in. Mold An polished unsaturated polyester mold surface was heated to a temperature between 149BC and 163 ° C under medium wave IR lamps at 42% intensity, after which one of the aforementioned powders (A, B, C) was electrostatically sprayed onto the inner wall of the mold with a triboelectric spray gun within 1 minute from the mold leaving the Ir lamps to cause the interface powder particles to melt and form a continuous coating that coats the mold surface. For 2 minutes after the application of the powder, the powder coated mold was replaced. under the medium wave IR lamps and heated to a surface temperature of about 177BC, during which time the powdered or molten particles above the interface powders were melted and coalesced towards the coating film and the film was cured. coating to a thermoset state, then the ST mold allowed to cool to room temperature. Subsequently, the alternate layers of fiberglass mat and filler resin were applied to the exposed side of the cured powder coating film by hand laying and then the filler resin was allowed to cure at room temperature. After the fill resin has sufficiently cured, the resulting product was separated from the mold and tested. This procedure was repeated for each of the aforementioned powders (A, B, C) with the exception that the powder (C) was subsequently cured after the curing of IR with UV radiation by passing the mold under a lamp. Fusion-V adulterated with gallium for 1-3 seconds. The performance properties of the individual coating powders (A, B, C) and the coating films formed therefrom are given below.

Results B Gelation time at 204aC (sec) 11 10 Hot Plate Melt Flow at 190aC (mm) 44 45 70 Resistance to sintering at 43aC under 100 g of weight for 12 hours Good Regular Good Resistance MEK (50 No, No, No, No, Double Rubings) corricorricorri tion ment 4-5 4-5 4-5 Softness (Orange Crust) None None No Porosity No Yes No Adhesion between Layers (Boiling Water) Without Without No Blisters Ampoules Ampoules Luster 60a 89 89 91 Luster 20a 74 70 78 Adhesion of Coating (ASTM D-3359) Good Good Good Results A B C Coating Flexibility Very Very Good Good Good Good Excellent Weather Meter No Good Xenon Are (ASTM No Depressed - Lightweight Tested- G-26-92?) (1500 hours) Rioro Mind Note- Better than ble Gel Coating Example 4 Comparison between Coating Powders in Mold of the Prior Art and the Invention The following ingredients were mixed together in the same manner as in Example 2 to form two different mold coating powder formulations, one formulation (1) made in accordance with this invention, and the other formulation (P) made in accordance with the general teachings of the US Patent 4,316,869 Ingredients Parts by Weight 1 P Polyster? Nsaturadp (from Example 1) 95 Aropol 7501 (Unsaturated Polyster) 1 80 Trialilocyanurate (Monomer.) 2 5 Isodialyl phthalate (Diallyl Ester Prepolymer) 5 20 Lupersol 231XL (peroxide initiator) 4.5 4. "5 Surfonyl 104-S (Flow Agent) 1 1 Modaflow 2000 (Agent for Acrylic Flow) 1 1. Moldwiz P-66 (Release Agent) 3 3 TR 93 TiQ2 ( Pigment)? 7 Fitting Notes: ^ ropol 7501 is an unsaturated polyether resin free of CHDM having a Tg of 601C, sold by Ashland Chemical. 2 Trialilocyanurate (TAC) is an unsaturated crosslinking monomer that has a melting point d? 27aC.

Then we tried to apply each formulation to a mold surface in the same way as e? Example 3. However, it was found that the formulation (P) underwent severe blockage at room temperature, ie, after half an hour of exposure to room temperature (approximately 22aC) the powder particles were turned into a solid, non-fluidizable lump. . . When trying to spray the formulation (P) through the corona discharge barrel after breaking the blocked powders by mechanical agitation, the powders were still piled up in the barrel and had to be mechanically released into the barrel by a template wire to of coating the mold surface. While the final film properties' achieved after curing the formulation (P) were only slightly worse than those of the formulation (1), - the formulation (P) due to its extremely low block strength is totally an unacceptable formulation for use in commercial electrostatic coating operations. The performance properties of the individual coating powders (P, 1) and the coating films formed therefrom are given below.

Results 1 P Gelification Time at 204SC (sec) 6 25 Hot Plate Melt Flow at 190aC (mm) 55 74 Sintering Resistance at 43aC low weight 100g for 12 sheets Good Very Bad Free Flow Powder at Temperature Si Do not Solid Grume Environment After Half Hour MEK Resistance (50 Rubings Without Co-No Corri- bilities) Smoothness (Orange Scratch) None •: None Luster 60a 91 82 Luster 20s 80 76 Meter? Xenon Weather Are Excellent Excellent (ÁSTM G-20-92A) (600 Hours) Without Dior-Observable Signs of Observation From the foregoing it will be seen that this invention TS is well adapted to achieve all the purposes and objects set forth above, together with the other advantages that are apparent and inherent.

Since many possible variations of the invention can be made without departing from the scope thereof, it is not intended that the invention be limited to the modalities of the examples described, which are considered to be purely exemplary. Accordingly, reference should be made to the appended claims to determine the true spirit and scope of the invention, in which ST claims exclusive rights.

Claims (8)

1. - A method for in-mold coating an article molded in an open mold, comprising: a) providing a powder composition of a thermosetting unsaturated polyester coating, consisting essentially of an unsaturated polyester resin, a copolymerizable crosslinking prepolymer; , and a thermal initiator, with the proviso that the composition is essentially free of a copolymerizable crosslinking monomer, b) applying the coating powder composition, which becomes the outer skin of the molded article, to a mold surface. "that imparts configuration; c) heating the powder-coated mold surface to a temperature sufficient to flow and coalesce the coating powder to a substantially continuous coating film and effect curing. with the temperature being lower than the deformation temperature of the mold; e) applying a filling resin, which constitutes the volume of the molded article, towards the cured powder coating and allowing the curing of the filling resin to progress sufficiently until the powder coating film and the filling resin are integral; and g) releasing the finished coated article from the mold.

2. The method according to claim 1, wherein the coating powder composition has the additional condition that any of the unsaturated polyester resin possesses an active hydrogen, or the powder composition additionally comprises A photoinitiator, or both, is essential

3. The method according to claim 1, wherein the coating powder composition further consists essentially of a curing catalyst

4. The method of compliance with claim 1. , wherein the coating powder composition further consists essentially of a mold release agent

5. The method according to claim 1, wherein, before step b) the mold surface is preheated at a temperature sufficient to flow and coalesce the coating powder to a substantially continuous film that coats the mold surface as the powder impinges on the surface of the film. mold during step b). 6, - The method of compliance with claim 1, wherein the mold is a. plastic mold, 7, - The method according to claim 1. wherein the filler resin is an unsaturated polyether filler resin. 8, - The method according to claim 1, wherein the filling resin is mixed with glass fibers, - The method according to claim 1, wherein the volume of the article is formed in step e) successively applying and curing as necessary the layers of filler resin and fiberglass mat over the cured powder coating, 10. The method according to claim 1, wherein the coating powder composition consists essentially of a unsaturated polyester resin containing active hydrogen atoms, a copolymerizable unsaturated prepolymer, a thermal initiator, a curing accelerator, and a mold release agent. 11. The method according to claim 10, wherein the unsaturated polyester resin is formed by reacting an unsaturated dicarboxylic acid or anhydride thereof selected from the group consisting of fumaric acid and maleic anhydride, with a diol containing active hydrogen at least comprising cyclohexane dimethanol, together with minor amounts of aromatic dicarboxylic acid or anhydride thereof comprising at least phthalic anhydride and an aromatic diol comprising at least hydrogenated bisphenol A. 12. The method according to claim 1, wherein the coating powder composition consists essentially of an unsaturated psester resin, a co-polymerizable unsaturated prepolymer, a thermal initiator, a photoinitiator, a curing catalyst, and an agent of mold release. 13. A powder coating composition in mold, whose composition is a film-forming mixture in the form of particles consisting essentially of: a) an unsaturated polyether resin; b) an unsaturated crosslinking prepolymer; c) a thermal initiator; and d) a mold release agent, with the provisos that: I) the composition is essentially free of a crosslinking monomer, and II) either the unsaturated polyether resin contains at least one active hydrogen atom, or the mixture it consists essentially also of a photoinitiator, or both. 14. The composition according to claim 13, wherein the mixture further consists essentially of: e) a curing catalyst. 15. The composition according to claim 14, wherein the unsaturated polyester resin contains unsaturation of maleate or fumarate and an active hydrogen selected from an allyl, benzyl, cyclohexyl, tertiary alkyl, and hydrogen of malonyl, the copolymerizable unsaturated prepolymer is a diallyl ester of an aromatic dicarboxylic acid, the initiator is a peroxide, and the catalyst is a cobalt salt of a fatty acid. 1

6. The composition according to claim 14, wherein the composition contains a photoinitiator and the unsaturated polyether resin contains maleate or fumarate unsaturation and is free of active hydrogen atoms, the copolymerizable unsaturated prepolymer is an ether urethane of divinyl, and the catalyst is a cobalt salt of a fatty acid, 1

7. A mold coated article, formed by the method of claim 1. 1

8. A heat-sensitive plastic mold having the coating powder of claim 13 coated and cured thereon without causing significant thermal damage to the mold. 19, - A heat sensitive plastic mold having the coating powder of claim 14 coated and cured thereon without causing significant thermal damage to the mold.