Product containing a reproduced image and method of forming a reproduced image layer

Abstract: The first invention provides an image reproduction I comprising a cured coating, a reproduced image layer and a clear coating of isocyanate-curing cellulose acetate butyrate-modified acrylic resin as laminated in this order, and a method of forming reproduced images on the surface of cured coating, the method comprising the steps of superposing, over a cured coating, a copying sheet which comprises a copy support having a reproduced image layer formed thereon to bring the reproduced image layer of the copying sheet into contact with the surface of the cured coating, heat-transferring the reproduced images to the surface of cured coating, releasing the copy support to provide a transfer on the cured coating, and forming a clear coating of isocyanate-curing cellulose acetate butyrate-modified acrylic resin on the surface of the transfer. The second invention provides an image reproduction II comprising a cured coating having a surface treated with an organic solvent of about 7.5 to about 8.2 in solubility parameter, a reproduced image layer and a clear coating as laminated in this order, and a method of forming reproduced images on the surface of cured coating, the method comprising the steps of treating a surface of the cured coating with the organic solvent, superposing, over a cured coating, a copying sheet which comprises a copy support having a reproduced image layer formed thereon to bring the reproduced image layer of the copying sheet into contact with the organic solvent-treated surface of cured coating, heat-transferring the reproduced images to the treated surface of cured coating, releasing the copy support to provide a transfer on the cured coating, and forming a clear coating on the surface of the transfer.

Description: The present invention relates to reproduced image products and a novel method of forming a layer of reproduced images on the surface of cured coating film. A method is known for forming a reproduced image layer on a substrate by heat transfer from a copying sheet comprising a copy support with images reproduced thereon from a pattern or the like using a color copying machine, the method comprising heat-transferring the reproduced images to a primer coating on the substrate, such as a tile, slate, plastics sheet or the like, releasing the copy support and applying a curable clear coating composition (Japanese Unexamined Patent Publication No.162435/1993). However, when said method is conducted on the surface of cured coating, as on an automotive cured coating, problems arise. Silicone is deposited on a copy support in forming a reproduced image layer thereon using a copying machine. Thereafter the silicone becomes attached to a primer coating or the reproduced images during heat transfer, thereby impairing the adhesion between the reproduced images and the primer coating or clear coating. As a result, the reproduced images or clear coating would readily come off from the primer coating due to an external force (scratching, collision, etc.), rain or like external factors, resulting in the decrease of durability. A further drawback is that cratering is created over the clear coating formed on the primer coating or on the reproduced image layer, deteriorating the finished appearance. For these reasons, it has been difficult to apply said method to the surface of cured coating. EP-A-0 318 230 discloses a method for coloring a solid object, comprising the steps of fitting, on an outer surface of the solid object, a coloring film having a base film, a peelable layer, a coloring layer and an adhesive layer, so that the adhesive layer adheres to the surface of the solid object; removing the base film so that the coloring layer remains on the surface of the solid object adhering thereto; and performing a hardening treatment on the coloring layer. An object of the present invention is to provide novel reproduced image products free of said prior art drawbacks. Another object of the invention is to provide a method capable of forming, on a cured coating, a reproduced image layer which is excellent in finished appearance, aesthetic property and durability. Other objects and features will become more apparent from the following description. According to the present invention there are provided a reproduced image product comprising a cured coating having a surface treated with an organic solvent of 15.345 to 16.777 (MPA) 1/2 (7.5 to 8.2 (cal/cm 3 ) 1/2 ) in solubility parameter, a reproduced image layer and a clear coating as laminated in this order and a method of forming reproduced images on the surface of cured coating, the method comprising the steps of treating a surface of the cured coating with an organic solvent of 15.345 to 16.777 (MPA) 1/2 (7.5 to 8.2 (cal/cm 3 ) 1/2 ) in solubility parameter, superposing, over a cured coating, a copying sheet which comprises a copy support having a reproduced image layer formed thereon to bring the reproduced image layer of the copying sheet into contact with the organic solvent-treated surface of cured coating, heat-transferring the reproduced images to the treated surface of cured coating, releasing the copy support to provide a transfer on the cured coating, and forming a clear coating on the surface of the transfer. The inventors of the present invention conducted extensive research to provide an image reproduction free from said prior art drawbacks and found the following. When reproduced images are heat-transferred after treating the surface of cured coating with a specific organic solvent, and a clear coating is applied, the adhesion of reproduced image layer to the cured coating is improved, the cratering of clear coating is prevented and the reproduced image layer which is excellent in finished appearance, aesthetic property and durability is formed. The present invention has been completed based on these novel findings. According to the second invention, there are provided an image reproduction II comprising a cured coating having a surface treated with an organic solvent of 15.345 to 16.777 (MPa) 1/2 (7.5 to 8.2 (cal/cm 3 ) 1/2 ) in solubility parameter, a reproduced image layer and a clear coating as laminated in this order, and a method of forming reproduced images on the surface of cured coating, the method comprising the steps of treating a surface of the cured coating with an organic solvent of 15.345 to 16.777 (MPa) 1/2 (7.5 to 8.2 (cal/cm 3 ) 1/2 ) in solubility parameter, superposing, over a cured coating, a copying sheet comprising a copy support having a reproduced image layer formed thereon to bring the reproduced image layer of the copying sheet into contact with the organic solvent-treated surface of cured coating, heat-transferring the reproduced images to the treated surface of cured coating, releasing the copy support to give a transfer product having a reproduced image layer on the cured coating, and forming a clear coating on the surface of the transfer product. Stated more specifically, the method of the invention is carried out as follows. (1) The surface of cured coating is treated with said specific organic solvent, and heat transfer is carried out using a copying sheet comprising a copy support having images reproduced thereon after superposing the surface of reproduced image layer of the copying sheet on the surface of cured coating treated with the organic solvent, giving a transfer product (v) comprising a cured coating having a surface treated with the organic solvent, a reproduced image layer and a copy support as superposed in this order. (2) The copy support is released from the transfer product (v), giving a transfer product (vi) comprising a cured coating having a surface treated with the organic solvent, and a reproduced image layer as superposed in this order. (3) A clear coating composition is applied to the surface of the transfer product (vi) and dried, giving a transfer product (vii) having a clear coating formed on the transfer product (vi). The invention is described below with reference to the drawings. FIG. 1 is a section view of a copying sheet which comprises a copy support 1 having a reproduced image layer 2 formed thereon. FIG. 2 is a section view of the transfer product (v) prepared by heat transfer in such a manner that the reproduced image layer of the copying sheet is superposed on a surface 7 of the cured coating 4 treated with the organic solvent. FIG. 3 is a section view of a transfer product (vi) formed by releasing the copy support from the transfer product (v) shown in FIG. 2. FIG. 4 is a section view of a transfer product (vii) having a clear coating 8 formed on the transfer product (vi) shown in FIG. 3. The transfer product (vii) is the image reproduction according to the present invention. The cured coating to be used in the method of the invention include conventional cured coatings which can be used without specific limitation. Among them, cured coatings formed for automotive use are preferably used. Automotive cured coatings include, for example, those comprising an undercoat, intercoat (which may be omitted) and topcoat as laminated on a metal substrate or plastics substrate. Topcoats for use herein include, for example, solid color coats, finished coats of metallic luster, finished coats of pearlescent luster, etc. Stated more specifically, topcoats employable herein include those comprising a solid colored coat, metallic coat or pearlescent coat as a base coat and a clear coat as a topcoat which are formed by 2-coat 1-bake, 3-coat 1-bake, or 3-coat 2-bake coating method. The topcoats for use herein include those formed from a topcoat coating composition containing a curable resin component which comprises a base resin (such as acrylic resin, polyester resin, alkyd resin, epoxy resin, silicone resin, fluorine-containing resin or the like) and a crosslinking agent (such as amino resin, polyisocyanate compound, polycarboxylic acid compound or the like). The topcoat composition is used in the form known per se, for example, in the form of a solution or a dispersion comprising said base resin, crosslinking agent and the like dissolved or dispersed in an organic solvent or water. The surface of cured coating for automotive use can be the surface of cured coating on any of new cars and used cars, or the surface of repaired coating. The surface of cured coating may be ground, degreased or otherwise treated when required in conducting the method of the present invention. The cured coatings for automotive use which are used in the invention can be as follows: The coating applied as a topcoat is preferably heated for curing to an extent avoiding the possibility that the cured coating may become softened due to the swelling and dissolution of cured coating caused by the organic solvent during the treatment and consequently may become deformed during heat transfer, reducing the clarity of reproduced images. The heating conditions may be properly selected depending on the type of the coating composition. For example, the coating is heated preferably at about 120 to about 180°C for about 20 to about 60 minutes when an amino resin or polycarboxylic acid compound is used as a curing agent. Before treatment with the organic solvent in the method of the invention, the resin coating composition for fixing the reproduced image may be applied to form an undercoat on a surface portion for forming a reproduced image layer. According to the method of the present invention, preferably a resin coating composition for fixing the reproduced image is applied to the surface of cured coating, especially automotive cured coating. Said coating composition is used to facilitate the heat transfer of reproduced images, to fix the transferred reproduced image layer and to affix the transfer to the cured coating, for contributing to the formation of a durable transfer layer. Isocyanate-curing acrylic resin coating compositions are suitable for use as the resin coating composition for fixing the reproduced image. More specific, desirable examples are isocyanate-curing acrylic resin coating compositions for a first or second coating to be described later and colored coating compositions containing a colored pigment as well as the acrylic resin composition. When the colored coating composition is used, a different color is formed in the background of the reproduced image layer, so that the reproduced images appear as if they were relieved or faded by the different color of the background. The resin coating composition for fixing the reproduced image, such as an isocyanate-curing acrylic resin coating composition, is applied, for example, by spraying, brushing or like means. The thickness of the coating, although suitably selectable according to the required properties and appearance, is usually about 10 to about 200 µm, preferably about 20 to about 100 µm. When the coating of the coating composition is dried for curing, the conditions for partial curing are so adjusted so as to provide the coating with the properties suited to heat transfer (heat softening properties). Stated more specifically, preferred conditions, although different depending on the type of the composition used and film thickness, are, for example, a film thickness of about 50 µm, and drying for about 6 to about 24 hours at 20°C or heating for about 10 to 60 minutes at 60°C. If the coating composition is not fully cured and the coating remains sticky, it would become difficult to heat-transfer the images to such coating. Even if heat transfer is forcedly conducted in this case, the reproduced images of high clarity would not be formed. On the other hand, if the coating composition is fully cured to provide a completely cured coating, a coating incapable of heat-softening may be produced, resulting in a disadvantage that the adhesion is impaired between the coating and the reproduced image layer. Hence such curing is undesirable. To determine whether the curing is complete or not, the softening properties at a heat transfer temperature are assessed. The curing extent can be determined by a simple method utilizing the solvent resistance. For example, if the luster of coating surface is reduced by scratching with xylol, the coating is partially crosslinked. If the luster is not altered at all, the coating is considered to have completely cured. The curing extent is also determined by a gel fraction ratio of coating. A suitable gel fraction ratio in the present invention is about 30 to about 80% by weight. The gel fraction ratio indicated herein was calculated by immersing an isolated coating in an acetone solvent, boiling the coating with refluxing for 8 hours, fully drying the same, and calculating the ratio by the equation (Weight of sample after extraction/weight of sample before extraction) X 100. In this case, the undercoat may be partially cured by heating or at room temperature. The undercoat thus formed gives an advantage that the adhesion between the cured coating and the reproduced image layer is stabilized without being affected by the type and age of cured coating. Preferably the cured coating or a coating formed on the cured coating from the resin coating composition for fixing the reproduced image (which may be hereinafter collectively referred to as "cured coating") is subjected to sanding with water-resistant paper or the like before treatment with the organic solvent. The organic solvent to be used for treating the surface of the cured coating is one incapable of dissolving the cured coating and having a low solvent power for dissolving the reproduced image layer of the copying sheet. In other words, if the organic solvent is capable of dissolving the cured coating, the cured coating when swollen or dissolved would become softened so that the cured coating would become deformed by heat transfer, resulting in failure to give a reproduced image layer with great clarity. If the organic solvent has too high a solvent power for dissolving the reproduced image layer of the copying sheet, the reproduced image is deformed by the pressure involved during heat transfer, and defects such as shrinks are caused in the reproduced image layer, leading to the reduced commercial value of the transfer product. Yet, if the organic solvent is entirely incapable of dissolving the reproduced image layer, the adhesion of the reproduced image layer to the cured coating is lowered. The organic solvent is variable in the solvent power for dissolving the cured coating and the reproduced image layer depending on the type or age (passage of time) of cured coating, the resin component of the printing ink used for forming a reproduced image layer, and other factors. Therefore, the organic solvent which is suitable for the specific conditions is properly selected for use. It is critical in the present invention to use the organic solvent with the foregoing properties which has a solubility parameter of 15.345 to 16.777 (MPa) 1/2 (7.5 to 8.2 (cal/cm 3 ) 1/2 ), The solubility parameter referred to herein is calculated by (cohesive energy density/molar volume) 1/2 . If the solubility parameter is less than 15.345 (MPa) 1/2 [7.5 to (cal/cm 3 ) 1/2 ], the adhesion between the cured coating and the reproduced image layer is likely to decrease due to its low solvent power for dissolving the reproduced image layer. Hence such solvent is undesirable to use. On the other hand, if a solubility parameter is more than 16.777 (MPa) 1/2 [8.2 (cal/cm 3 ) 1/2 ], there arise, due to its high solvent power for dissolving the reproduced image layer, deformation and shrinks of reproduced image layer, and cratering of clear coating caused by the inability to control the action of silicone on the surface of reproduced image layer and cured coating owing to a low permeability into the cured coating and the reproduced image layer. Hence the solvent with such parameter is undesirable to use. The above-mentioned solubility parameter of the organic solvent applies to a mixture of 2 or more solvents. The solubility parameter of a mixture of at least two solvents can be calculated by the following equation: S 1 X Φ 1 + S 2 X Φ 2 ..... (wherein S 1 , S 2 , .. mean the solubility parameter of each solvent of the mixture, and Φ 1 , Φ 2 .... mean the volume fraction of each solvent of the mixture. A small quantity of the organic solvent used for treating the cured coating preferably remains on the surface of the coating until superposition of the copying sheet on the cured coating. If a large quantity of the organic solvent used for treatment is left on the surface of cured coating in heat transfer, foaming would be caused by heat transfer and the durability of the reproduced image layer would be lowered. If the organic solvent has completely dried up, it becomes impossible to control the action of silicone on the surface of reproduced image layer and cured coating, causing cratering to occur on the clear coating and reducing the adhesion of the clear coating. Hence the complete absence of the solvent is undesirable. The amount of the organic solvent which should remain on the surface of cured coating depends largely on the boiling point of the organic solvent. The boiling point of the solvent is about 60 to about 250°C, preferably about 100 to about 230°C when the organic solvent is used singly. If a mixture of organic solvents is used, preferably the solvent having said boiling point accounts for at least about 50% by weight, or preferably about 60% by weight, of the mixture. If the organic solvent has a boiling point of lower than about 60°C, the solvent would remain on the surface of coating for a shorter period, and only a short time could be left for heat transfer. If the organic solvent has a boiling point of over about 250°C, the solvent is apt to remain between the cured coating and the reproduced image layer or in the reproduced image layer, resulting in the decrease of adhesion and durability. Hence the solvent is undesirable to use. Examples of preferred organic solvents are heptane, mineral spirit, ethylcyclohexane, kerosene, turpentine oil, dipentene, "Shellsol D70" (trademark, product of Shell Chemical Co., Ltd.), "Exxon Naphtha No.3" (trademark, product of Exxon Chemical Co., Ltd.), "IP Solvent 1016" (trademark, product of Idemitsu Petrochemical Co., Ltd.), etc. In the treatment with the organic solvent in the method of the invention, the organic solvent used therein does not dissolve the cured coating, but slightly dissolves the reproduced image layer and has a specific solubility parameter. Such organic solvent is applied to the cured coating so that some portion of the solvent would remain. A surface of the cured coating is treated with the organic solvent, for example, by being coated with the organic solvent using a spray coater, roll coater or the like or by being rubbed with a fabric, sponge or cotton piece soaked with the organic solvent. The organic solvent is used for the treatment in an amount of about 20 to about 150 g, preferably about 30 to about 100 g, per square meter of cured coating. The silicone (which has been affixed to a copy support in forming reproduced images on the copy support using a copying machine) is deposited on the cured coating and on the reproduced image layer during heat transfer. Then the silicone is dissolved in or diluted with the organic solvent remaining after treatment. Further the silicone thus dissolved or diluted is caused to become permeated or dispersed on the cured coating and the reproduced image layer formed thereon, whereby presumably the action of the silicone is controlled, resulting in markedly improved adhesion of reproduced image layer to the cured coating, and in avoided cratering of a clear coating composition to be subsequently applied. The reproduced image layer of the copying sheet is superposed on the surface of cured coating treated in this way with the organic solvent to accomplish heat transfer while the organic solvent remains. FIG. 2 is a section view of the transfer product (v) thus obtained. As described hereinbefore, the copying sheet has a copy support with a reproduced image layer formed thereon as shown in FIG. 1. The surface of the copying sheet may be heated by a drier or the like before heat transfer to remove the moisture from the sheet so that the sheet can be prevented from shrinking. The heat transfer can be carried out using a dryer for industrial use or for household use at a sheet temperature of about 30 to about 100°C, preferably about 30 to about 70°C for about 30 to about 120 seconds (in the case of A4 size) while pressing the copying sheet against the cured coating. A sheet temperature lower than about 30°C reduces the adhesion between the cured coating and the reproduced image layer, whereas a sheet temperature of higher than 100°C allows the organic solvent to readily dissolve the reproduced image layer, thereby bringing about the shrinks on the reproduced image layer or lowering the clarity of the reproduced image layer. Hence the sheet temperature outside said range is undesirable. When required, the surface of the transfer may be lightly rubbed with a fabric piece to smooth out the crumpled film by removing the air from between the cured coating and the reproduced image layer while the reproduced image layer is warm, so that the reproduced image layer is uniformly attached to the surface of the cured coating. The copy support is released or removed from the reproduced image layer after transfer. The release can be done in the same manner as in the first invention. The obtained transfer product (vi) comprises a cured coating 4 having a surface 7 treated with the organic solvent, and a reproduced image layer 2 laminated in this order as shown in FIG. 3. Thereafter, a clear coating composition is applied to the surface of the above-obtained transfer product and dried to give a clear coating. It is not important whether the organic solvent has been remaining or not during the application of the clear coating composition. The clear coating composition useful in the invention can be used as selected without limitation from conventional non-crosslinking or crosslinking coating compositions, According to the method of the present invention, an isocyanate-curing cellulose acetate butyrate-modified acrylic resin clear coating composition is applied to the surface of the reproduced image layer of the transfer product (ii) and dried to give a first clear coating. Such specific clear coating composition can be prevented from cratering. The isocyanate-curing cellulose acetate butyrate-modified acrylic resin clear coating composition for forming the clear coating comprises cellulose acetate butyrate (hereinafter referred to as "CAB")-modified acrylic resin as a base resin and a polyisocyanate compound as a curing agent. The CAB-modified acrylic resin is produced by radical polymerization reaction of a mixture of CAB, hydroxyl-containing acrylic monomer and, when necessary, other radically polymerizable monomer. The CAB which can be used herein is a cellulose derivative prepared by butyl-esterifying partially acetylated cellulose. A preferred CAB has an acetyl group content of about 1 to about 30% by weight, preferably about 1 to about 14% by weight and a butyl group content of about 16 to about 60% by weight, preferably about 35 to about 60% by weight. Suitable examples of commercially available products include, for example, "EAB-381" (trademark, product of Eastman-Kodak Co.), "EAB-551" (trademark, product of Eastman-Kodak Co.), etc. Examples of the hydroxyl-containing acrylic monomer are compounds having one hydroxyl group, and one (meth)acryloyl group, per molecule such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, ethylene glycol mono(meth)acrylate, propylene glycol mono(meth)acrylate, and hydroxyl-containing acrylic monomers prepared by modifying these monomers with ε-caprolactone. Examples of the other radically polymerizable monomer include compounds having a radically polymerizable, α,β-ethylenically unsaturated bond per molecule, such as styrene, its derivatives, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and like alkyl esters of (meth)acrylic acids, (meth)acrylic acids, (meth)acrylonitrile, etc. In the copolymerization for preparing the CAB-modified acrylic resin, the monomers are used in the following proportions: based on the total amount of the monomers used, about 10 to about 30% by weight, preferably about 15 to about 25% by weight, of the CAB; about 1 to about 50% by weight, preferably about 5 to about 35% by weight, of the hydroxyl-containing acrylic monomer; and about 20 to about 89% by weight, preferably about 40 to about 80% by weight, of the other radically polymerizable monomer. If the proportion of the CAB is below 10% by weight, the coating composition for a second clear coating which is applied in the subsequent step when required is likely to cause cratering, and hence this proportion is undesirable. On the other hand, the proportion of above 30% by weight reduces the surface smoothness of the second clear coating, and hence is undesirable. The hydroxyl-containing acrylic monomer used in a proportion of below about 1% by weight lowers the curability of the composition, and impairs the water resistance, weatherability and processability and like coating properties. Hence said proportion is undesirable. If the proportion is above about 50% by weight, hydroxyl groups which can not be cured with a polyisocyanate curing agent would remain in an increased amount, resulting in the decrease of water resistance, weatherability and like coating properties. Hence said proportion is undesirable. Suitably the CAB-modified acrylic resin has a weight average molecular weight of about 5,000 to about 200,000, preferably about 8,000 to about 100,000. The weight average molecular weight of less than about 5,000 reduces the water resistance, weatherability, processability and other coating properties and deteriorates the finished appearance of the second clear coating (cratering, etc.), and hence is undesirable. On the other hand, the weight average molecular weight of more than about 200,000 lowers the surface smoothness of the second clear coating, and hence is undesirable. Preferred polyisocyanate compounds are those free of yellowing. Examples of such compounds are aliphatic diisocyanate compounds such as trimethylene diisocyanate, hexamethylene diisocyanate, etc., alicyclic diisocyanate compounds such as isophorone diisocyanate, etc., biuret-type addition reaction products of these polyisocyanate compounds or isocyanurate ring type addition reaction products thereof, polyol-modified compounds thereof, and so on. The proportions of the CAB-modified acrylic resin and the polyisocyanate compound are about 0.8-1.5 in terms of NCO/OH equivalent ratio. When required, the coating composition for the clear coating may contain an organic solvent, rheology control agent, ultraviolet stabilizer, ultraviolet absorber and like additives. It is desirable that the coating composition for the clear coating have a surface tension of up to 30 dyne/cm. A higher surface tension tends to bring about cratering of the composition and hence is undesirable. The surface tension can be adjusted, for example, with a silicone type additive. The coating composition for the clear coating can be applied by spraying, brushing or like means. The thickness of the first clear coating can be properly selected according to the required properties and appearance. Usually the thickness of cured coating is in the range of about 10 about 200 µm, preferably about 20 to about 100 µm. The composition is dried for curing to an extent avoiding the possibility that the coating composition for the second clear coating will be dissolved in or mixed with the first clear coating, thereby impairing the finished appearance. Such drying conditions, although variable depending on the type and proportion of the composition, are sufficient if the coating is dried, for example, for about 6 to about 48 hours at about 20°C or heated for about 10 minutes to about 2 hours at about 60°C. The clear coating composition for forming the clear coating can be selected without limitation from conventional non-crosslinking solvent-vaporizable coating compositions, room temperature-crosslinking coating compositions, heat-crosslinking coating compositions and activation energy radiation crosslinking coating compositions. The coating composition to be used herein are not specifically limited. Typical examples are as described below. The non-crosslinking solvent-vaporizable coating compositions are capable of forming a dried coating merely by the vaporization of a solvent. Examples of such compositions are those containing, as a main component, a cellulose derivative which is soluble in a solvent, such as nitrocellulose, acetylcellulose, benzylcellulose or the like. The room temperature-crosslinking coating compositions are curable by crosslinking at room temperature, and include, for example, coating compositions containing a room temperature-curable resin as a main component. Examples of such resins are oxidation-polymerizable resins such as oxidation-polymerizable unsaturated group-containing unsaturated fatty acids, oxidation-polymerizable unsaturated group-containing alkyd resins, etc.; moisture-curing resins such as isocyanate group-containing acrylic resins, alkoxysilyl group-containing acrylic resins, alkoxysilyl group-containing silicon-modified polyester resins, etc.; curable resins comprising a hydroxyl-containing resin such as polyether polyol, polyester polyol, acryl polyol or the like, and a polyisocyanate curing agent; radical reaction-curable resins comprising an unsaturated polyester resin and a peroxide; and mixtures of these resins. Heat-crosslinking coating compositions are curable on crosslinking by heating preferably at about 140°C or lower, and include those comprising a heat-curable resin or the like as a main component. Examples of the resin as the main component are self-curing resins such as N-methylol group-containing acrylic resins, etc.; curable resins such as those comprising polyether polyol, polyester polyol, acryl polyol or like hydroxyl-containing resins and a curing agent such as amino resin, blocked polyisocyanate or the like, those comprising acrylic resin, polyester resin or like polycarboxylic acid resins and a polyepoxide crosslinking agent; and mixtures of these resins, etc. Activation energy radiation crosslinking coating compositions are those which are curable on crosslinking by irradiation with activation energy radiation. Examples of such compositions are those comprising, as a main component, an activation energy radiation curable unsaturated group-containing acrylic resin, polyester resin, silicone resin, polyether resin, or a mixture of these resins. Where necessary, these coating compositions may contain cratering inhibitors, surface control agents, UV absorbers, UV stabilizers, curing catalysts, transparent pigments, transparent fillers, etc. and also may contain a coloring agent in an amount which does not hide the reproduced image layer, such as colored pigments, metal flakes and colored mica, etc. The clear coating composition for use in the invention can be any of organic solvent solution compositions, organic solvent dispersion compositions, aqueous solution compositions, aqueous dispersion compositions, powder compositions, etc. Among these clear coating compositions, it is suitable to use an isocyanate-curing acrylic resin clear coating composition comprising a hydroxyl-containing acrylic resin as a base resin and a polyisocyanate compound as a curing agent, the composition being excellent in finished appearance, low-temperature curability, weatherability, etc. Hydroxyl-containing acrylic resins are those prepared by radical polymerization of a mixture of hydroxyl-containing acrylic monomer and, as necessary, other radically polymerizable monomer. Examples of useful hydroxyl-containing acrylic monomers and other radically polymerizable monomers optionally used include those exemplified above. In the copolymerization for preparing the hydroxyl-containing acrylic resin, the monomers are used in the following proportions: based on the total amount of the monomers used, about 1 to about 50% by weight, preferably about 5 to about 35% by weight, of the hydroxyl-containing acrylic monomer; and about 50 to about 99% by weight, preferably about 65 to about 95% by weight, of the other radically polymerizable monomer. If the proportion of the hydroxyl-containing acrylic monomer is about 1% or less by weight, the coating composition is reduced in curability and impaired in water resistance, weatherability, processability and like coating properties. Hence said proportion is undesirable. On the other hand, if the proportion is above about 50% by weight, hydroxyl groups which can not be cured with a polyisocyanate curing agent would remain in an increased amount, resulting in the decrease of water resistance, weatherability and other coating properties. Hence said proportion is undesirable. The hydroxyl-containing acrylic resin has suitably a weight average molecular weight of about 6,000 to 100,000, preferably about 8,000 to 80,000. The weight average molecular weight of less than about 6,000 reduces the water resistance, weatherability, processability and other coating properties and hence is undesirable. On the other hand, the weight average molecular weight of more than about 100,000 lowers the surface smoothness of the coating, and hence is undesirable. Useful polyisocyanate compounds include those exemplified above. The proportions of the hydroxyl-containing acrylic resin and polyisocyanate compound are about 0.8-1.5 in terms of NCO/OH equivalent ratio. The coating composition for the clear coating is applied, for example, by spraying, brushing or like means. The thickness of the coating, although suitably selectable according to the required properties and appearance, is usually about 10 to about 200 µm, preferably about 20 to about 100 µm. The drying conditions are variously selected depending on the type and proportion of the composition. Usually the drying is conducted for about 6 to about 48 hours at about 20°C or for about 10 minutes to about 2 hours at about 60°C. Preferred clear coating compositions are isocyanate-curing acrylic resin clear coating compositions comprising a hydroxyl-containing acrylic resin as a base resin and a polyisocyanate compound as a curing agent. The transfer product (vii) prepared according to the invention comprises a cured coating 4 having a surface 7 treated with an organic solvent, a reproduced image layer 2, and a clear coating 8 laminated in this order as shown in FIG. 4. The cured coating may include a cured image-fixing layer, when so required. According to the method of the invention, the reproduced image layer which is excellent in finished appearance, aesthetic property and durability (e.g. water resistance) is formed on the cured coating, especially automotive cured coating. Such remarkable effects can be produced by the method of the invention for the following reasons. The silicone adhering to the cured coating and to the reproduced image layer formed thereon (the silicone attached to the copy support in forming a reproduced image layer on the copy support of a copying sheet using a copying machine is deposited, during heat transfer, on the cured coating and the reproduced image layer) is dissolved in or diluted with the organic solvent remaining after treatment with the solvent and is permeated and dispersed in the cured coating and the reproduced image layer formed thereon, with the result that presumably the action of silicone is controlled, and therefore the adhesion of the reproduced image layer is markedly improved and a clear coating composition to be subsequently applied is prevented from cratering. The present invention is described below in more detail with reference to the following examples and comparative examples. Examples and Comparative Examples Example 1 A copying sheet was produced by reversely reproducing images from a pattern as the original drawing on a copy support using "Color Laser Copier Piccel 700" (trademark, product of Canon Inc., toner type) as a color copying machine. The copy support was one available under "Copress 4H" (trademark, product of Osaka Taiyo Bussan Co., Ltd.) and had an image-forming resin layer and release paper (A4 size). A surface portion of coated automotive exterior panel (exterior panel coated with white cured coating of melamine-curing acrylic resin coating composition, baked at 140°C for 30 minutes, 60 cm X 60 cm) to be used for heat transfer was subjected to wet sanding with water resistant paper # 1000, and dried. The dried coating was sprayed with about 30 to about 40 g/m 2 of mineral spirit (solubility parameter 16.573 (MPa) 1/2 [8.1 (cal/cm 3 ) 1/2 ] boiling point 150 to 205°C) for treatment with the organic solvent. The reproduced image layer of the copying sheet was superposed on the surface of cured coating treated with the organic solvent in contact with each other. Then, release paper was removed from the copying sheet. The copying sheet was heated from the side of image-forming resin layer with a drier to a film temperature of 40 to 50°C. The surface of the copying sheet was lightly rubbed with paper to press the reproduced image layer against the cured coating while eliminating the organic solvent and bubbles from between them, giving a transfer product (v) comprising an automotive cured coating, a reproduced image layer and an image-forming resin layer as laminated in this order. The obtained transfer product was left to stand at room temperature for 30 minutes for cooling. Water was sprinkled over the surface of the image-forming resin layer of the transfer product. Then, the image-forming resin layer was removed by rubbing with fingers. The transfer product was washed with a neutral detergent and with water, and dried by draining, giving a transfer product (vi) comprising an automotive cured coating having a surface treated with an organic solvent, and a reproduced image layer as laminated in this order. Diluted with a solvent was a clear composition comprising 70 parts by weight (calculated as solids) of an acrylic resin [with a monomer composition of 2-hydroxyethyl methacrylate/styrene/methyl methacrylate/ethyl acrylate= 20/16/26/38 (weight ratio), weight average molecular weight about 20,000], and 30 parts by weight (calculated as solids) of hexamethylene diisocyanate. Added to the diluted composition was 0.1 parts by weight of "BYK-306" (trademark, product of BYK Co., silicone-type additive), giving a clear coating composition of isocyanate-curing acrylic resin. The clear composition thus obtained was applied by spraying to the surface of the transfer product (vi) to a thickness of about 60 µm (when cured), set for about 20 minutes and baked at 60°C for 60 minutes, giving a transfer product (vii) comprising an automotive cured coating with a surface treated with an organic solvent, a reproduced image layer and a cured clear coating as laminated in this order. Example 2 The procedure of Example 1 was repeated with the exception of spraying the coated automotive exterior panel (exterior panel coated with white coating film of melamine-curing acrylic resin coating composition) used in Example 1 with the isocyanate-curing acrylic resin clear coating composition used in Example 1 to a thickness of about 60 µm when cured, setting the coated panel for about 20 minutes, and baking the same at 60°C for 30 minutes to form an image-fixing layer, whereby a transfer product (vii) comprising an automotive cured coating (including a cured clear coating) having a surface treated with an organic solvent, a reproduced image layer and a cured clear coating as laminated in this order. Examples 3 to 9 The procedure of Example 2 was repeated with the exception of using the organic solvents shown below in Table 1, thereby producing a transfer product (vii) comprising an automotive cured coating (including a cured clear coating) having a surface treated with an organic solvent, a reproduced image layer and a cured clear coating as laminated in this order. Comparative Example 1 The procedure of Example 1 was repeated with the exception of not using the organic solvent, producing a transfer product comprising an automotive cured coating, a reproduced image layer and a cured clear coating as laminated in this order. Comparative Example 2 The procedure of Example 2 was repeated with the exception of not using the organic solvent, producing a transfer product comprising an automotive cured coating (including a cured clear coating), a reproduced image layer and a cured clear coating as laminated in this order. Comparative Examples 3 to 5 The procedure of Example 2 was repeated with the exception of using the organic solvents shown in Table 1, thereby producing a transfer product comprising an automotive cured coating (including a cured clear coating) with a surface treated with an organic solvent, a reproduced image layer and a cured clear coating as laminated in this order. The transfer products prepared in Examples 1 to 9 and Comparative Examples 1 to 5 were evaluated in properties by the following test methods. Condition of transfer The surface of the reproduced image layer was checked as to the transfer products prepared by removing the image-forming resin layer and drying by draining for 4 hours in Examples and Comparative Examples, namely the transfer products comprising an automotive cured coating (including a cured clear coating) and a reproduced image layer. The surface of the reproduced image layer was assessed as follows: A, free of shrinks and popping and acceptable; B, some shrinks but no problem posed when used; C, suffering shrinks and unacceptable; and D, suffering both shrinks and popping and unacceptable. Adhesion of reproduced image layer The adhesion test was carried out on the transfer products prepared by the same method as stated above in the test for the condition of transfer. The transfer product was cut with a sharp cutter to the automotive cured coating to produce 100 squares, 2 mm X 2 mm. Then, cellophane tape was applied over the surface of squares and removed. The peeling extent was amassed as follows: A, no peeling; B, slightly peeled along the cut or the coating remaining on at least 98% of the adhering area; C, the coating remaining on 80 to about 98% of the adhering area; and D, the coating remaining on less than 80% of the adhering area. Finished appearance The appearance of the transfer product finally obtained was visually evaluated as to craters, etc. as follows: A, good in appearance; B, slightly poor in appearance, and no problem posed in use; C, impaired in appearance; and D, pronouncedly impaired in appearance. Water resistance The transfer product finally obtained was immersed in tap water at 40°C for 240 hours, dried and checked for appearance and adhesion. The appearance was evaluated as follows: A, no blister; B, a few blisters; C some blisters, and D, blisters abounding. The adhesion was evaluated by cutting the surface of the clear coating to the automotive cured coating and subsequently following the same procedure as done in the test for the adhesion of reproduced image layer. The results are shown in Table 1. The organic solvents listed above in Table 1 have the following solubility parameters and boiling points. Mineral spirit: 16.573 (MPa) 1/2 [8.1 (cal/cm 3 ) 1/2 ] in solubility parameter, 150 to 205°C in boiling point. Exxon Naphta No.3: (Trademark, product of Exxon Chemical Co.), 15.959 (MPa) 1/2 [7.8 (cal/cm 3 ) 1/2 ] in solubility parameter, 85 to 124°C in boiling point Ethylcyclohexane: 16.136 (MPa) 1/2 [7.9 (cal/cm 3 ) 1/2 ] in solubility parameter, 131°C in boiling point Toluene 18.209 (MPa) 1/2 [8.9 (cal/cm 3 ) 1/2 ] in solubility parameter, 110°C in boiling point Swasol #310: (Trademark, product of Maruzen Oil Co., Ltd.), 16.982 (MPa) 1/2 [8.3 (cal/cm 3 ) 1/2 ] in solubility parameter, 153 to 180°C boiling point n-Hexane: 14.731 (MPa) 1/2 [7.2 (cal/cm 3 ) 1/2 ] in solubility parameter, 69°C in boiling point

Claims: A reproduced image product comprising a cured coating having a surface treated with an organic solvent of 15.345 to 16.777 (MPa) 1/2 [7.5 to 8.2 (cal/cm 3 ) 1/2 ] in solubility parameter, a reproduced image layer and a clear coating as laminated in this order. The reproduced image product according to claim 1, wherein the organic solvent has a boiling point of 60 to 250°C. The reproduced image product according to claim 1, wherein the cured coating has a cured coating for fixing the reproduced image. A method of forming reproduced images on the surface of cured coating, the method comprising the steps of treating a surface of the cured coating with an organic solvent of 15.345 to 16.777 (MPa) 1/2 [7.5 to 8.2 (cal/cm 3 ) 1/2 ] in solubility parameter, superposing, over a cured coating, a copying sheet which comprises a copy support having a reproduced image layer formed thereon to bring the reproduced image layer of the copying sheet into contact with the organic solvent-treated surface of cured coating, heat-transferring the reproduced images to the treated surface of cured coating, releasing the copy support to provide a transfer on the cured coating, and forming a clear coating on the surface of the transfer. The method according to claim 4, wherein (1) the surface of cured coating is treated with an organic solvent of 15.345 to 16.777 (MPa) 1/2 [7.5 to 8.2 (cal/cm 3 ) 1/2 ) in solubility parameter, and heat transfer is carried out using a copying sheet comprising a copy support having images reproduced thereon after superposing the surface of reproduced image layer of the copying sheet on the surface of cured coating treated with the organic solvent, giving a transfer product (v) comprising a cured coating having a surface treated with the organic solvent, a reproduced image layer and a copy support as superposed in this order, (2) the copy support is released from the transfer product (v), giving a transfer product (vi) comprising a cured coating having a surface treated with the organic solvent, and a reproduced image layer as superposed in this order, and (3) a clear coating composition is applied to the surface of the transfer product (vi) and dried, giving a transfer product (vii) having a clear coating formed on the transfer product (vi). The method according to claim 5, wherein the organic solvent has a boiling point of 60 to 250°C. The method according to claim 5 or 6, wherein the cured coating has a cured coating for fixing the reproduced image. The method according to claim 5, 6 or 7, wherein the coating composition for forming the clear coating is an isocyanate-curing acrylic resin clear coating composition.

Inventors: HAGA HIDEO, INOUE KYOJI, MIYATAKE KEIJI, NAGASAO TSUTOMU, NAKASHIMA MOTOHITO, OGATA KENTARO, SUZUKI AKIRA, TOMIYAMA TAKESHI, HAGA, HIDEO, INOUE, KYOJI, MIYATAKE, KEIJI, NAGASAO, TSUTOMU, NAKASHIMA, MOTOHITO, OGATA, KENTARO, SUZUKI, AKIRA, TOMIYAMA, TAKESHI
Applicants: KANSAI PAINT CO LTD, TOYOTA MOTOR CO LTD, KANSAI PAINT CO. LTD., TOYOTA JIDOSHA KABUSHIKI KAISHA
Application year: 1996
Main classification: B44C5
IPC codes: B44C5, B41M5, B44C1, B41M7