Patent Application
20080069982
Thermal transfer sheets according to the first to fourth aspects of the present invention will be described with reference to
Another embodiment of thermal transfer sheets according to the first to fifth aspects of the present invention will be described with reference to
First Aspect of the Present Invention
1. Adhesive Layer
The adhesive layer according to the first aspect of the present invention comprises a modified polyvinylpyrrolidone resin. Since the modified polyvinylpyrrolidone resin per se is antihygroscopic, the hygroscopic properties of the thermal transfer sheet used under high humidity conditions can be significantly suppressed. Therefore, as compared with an adhesive layer formed of a polyvinylpyrrolidone resin alone, the adhesion between the dye layer and the substrate under high temperature and high humidity conditions can be improved.
The adhesive layer comprises a modified polyvinylpyrrolidone. The modified polyvinylpyrrolidone resin is a copolymer of an N-vinylpyrrolidone monomer with other monomer. The N-vinylpyrrolidone monomer mainly refers to N-vinylpyrrolidone, such as N-vinyl-2-pyrrolidone and N-vinyl-4-pyrrolidone, and its derivatives. Specific examples of such derivatives include compounds having a substituent in the pyrrolidone ring, for example, N-vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-3,3,5-trimethylpyrrolione, and N-vinyl-3-benzylpyrrolidone. The copolymerization method is not particularly limited, and example of polymerization methods include random copolymerization, block copolymerization, and graft copolymerization.
A vinyl polymerizable monomer may be mentioned as the monomer component copolymerizable with the N-vinylpyrrolidone monomer. Specific examples of vinyl polymerizable monomers include (meth)acrylic monomers such as (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, and isopropyl (meth)acrylate, unsaturated carboxylic acids such as fumaric acid, maleic acid, and itaconic acid, ethylene, propylene, vinyl chloride, vinyl acetate, vinyl alcohol, styrene, vinyltoluene, divinylbenzene, vinylidene chloride, ethylene tetrafluoride, and vinylidene fluoride. In the present invention, since a copolymer of vinyl acetate or styrene monomer with the N-vinylpyrrolidone monomer is antihygroscopic, the adhesion between the dye layer and the substrate can be advantageously improved even under a high temperature and high humidity environment. The modified polyvinylpyrrolidone resin may be synthesized by using an N-vinylpyrrolidone monomer component and other comonomer component at a molar ratio of about 10% to 80% (N-vinylpyrrolidone monomer component/N-vinylpyrrolidone monomer component+other comonomer component).
The addition amount of the modified polyvinylpyrrolidone resin is preferably 10% by weight to 50% by weight based on the total solid content of the component for adhesive layer formation. When the addition amount falls within the above-defined range, as compared with an adhesive layer formed of only a polyvinylpyrrolidone resin as a straight chain polymer, the adhesion between the dye layer and the substrate under high temperature and high humidity conditions can be enhanced and, consequently, for example, abnormal transfer at the time of thermal transfer of the thermal transfer sheet can be significantly prevented.
The adhesive layer may further comprise other resins. Specific examples of other resins include polyvinylpyrrolidone resins, polyvinyl alcohol resins, and cellulose derivatives. Specific examples of polyvinylpyrrolidone resins include homopolymers of vinylpyrrolidones such as N-vinyl-2-pyrrolidone and N-vinyl-4-pyrrolidone, or copolymers of thereof. In particular, polyvinylpyrrolidone resins as a straight chain polymer are preferred because the effect of improving the sensitivity in transfer in printing is high and, at the same time, the adhesive between the dye layer and the substrate is good.
Preferably, the polyvinylpyrrolidon resin has a K value in a Fickencher's formula of not less than 60, and grades of K-60 to K-120 are particularly preferred. When the polyvinylpyrrolidone resin has a K value of not less than 60, the sensitivity in transfer in printing can be advantageously improved. The polyvinylpyrrolidone resin may have a number average molecular weight of about 30,000 to 280,000.
Formation of Adhesive Layer
The adhesive layer may be formed by optionally adding an additive to a modified polyvinylpyrrolidone resin (preferably a modified polyvinylpyrrolidone resin mixed with a straight chain polyvinypyrrolidone resin), dissolving or dispersing the resin in water or an aqueous solvent such as alcohols or an organic solvent to prepare a coating liquid and coating the coating liquid onto a substrate by conventional coating means such as gravure printing, screen printing, or reverse roll coating using a gravure plate. The coverage of the component for forming the adhesive layer (coating liquid) is about 0.01 to 0.3 g/m2, preferably 0.05 to 0.15 g/m2, on a dry basis. When the coverage is in the above-defined range, the concaves and convexes on the substrate can be eliminated by filling with the coating to form an even surface, that is, no uncoated part occurs. As a result, an abnormal transfer phenomenon that, in the thermal transfer, the dye layer is disadvantageously transferred onto the receptive layer side of the image receiving sheet, can be effectively prevented. Further, mixing of the adhesive layer with the dye layer at the time of coating of the dye layer can be prevented, and, thus, in the thermal transfer, abnormal transfer of the receptive layer onto the dye layer side can be effectively prevented.
2. Substrate
The substrate may be any material so far as it has a certain level of heat resistance and strength. For example, polyethylene terephthalate films, 1,4-polycyclohexylene dimethylene terephthalate films, polyethylene naphthalate films, polyphenylene sulfide films, polystyrene films, polypropylene films, polysulfone films, aramid films, polycarbonate films, polyvinyl alcohol films, cellophane, cellulose derivatives such as cellulose acetate, polyethylene films, polyvinyl chloride films, nylon films, polyimide films, and ionomer films may be mentioned as specific examples of such substrates. The thickness of the substrate is 0.5 to 50 μm, preferably about 1 to 10 μm.
In the present invention, in forming an adhesive layer on the substrate according to the present invention, when the adhesive layer has satisfactory adhesion to the substrate, the adhesive layer can be provided directly on the substrate without adhesion treatment of the substrate. For example, an adhesive component can be added to the adhesive layer to enhance the adhesion to the substrate.
In the present invention, however, adhesion treatment can be carried out on the substrate in its surface where the adhesive layer and the dye layer are formed. When the substrate is formed of a plastic film, this adhesion treatment is particularly preferred because, when an adhesive layer is formed by coating on the substrate, the wetting properties, adhesion and the like of the coating liquid can be improved. Conventional resin surface modification techniques such as corona discharge treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, roughening treatment, chemical agent treatment, plasma treatment, low-temperature plasma treatment, primer treatment, and grafting treatment may be applied as the adhesion treatment. A combination of two or more of these treatment methods may also be used. The primer treatment may be carried out, for example, by coating, in melt extrusion of a plastic film to form a film, a primer liquid onto an unstretched film and then subjecting the assembly to stretching treatment.
Primer Layer
The adhesion treatment can be carried out by coating a primer layer between the substrate and the adhesive layer. The primer layer may be formed of a resin, and examples of such resins include polyester resins, polyacrylic ester resins, polyvinyl acetate resins, polyurethane resins, styrene acrylate resins, polyacrylamide resins, polyamide resins, polyether resins, polystyrene resins, polyethylene resins, polypropylene resins, vinyl resins such as polyvinyl chloride resins and polyvinyl alcohol resins, and polyvinyl acetoacetal resins such as polyvinylacetoacetal and polyvinylbutyral.
3. Dye Layer
The dye layer may be formed as a single layer of one color, or alternatively may be formed as a plurality of layers containing dyes with different hues. The dye layer may be formed repeatedly in a face serial manner on an identical plane of the identical substrate. The dye layer is a layer comprising a thermally transferable dye supported by any desired binder. Dyes, which are thermally melted, diffused or transferred by sublimation, are usable in the dye layer, and any dye used in conventional dye sublimation thermal transfer sheets may be used. The dye may be properly selected by taking into consideration, for example, hue, sensitivity in printing, lightfastness, storage stability, and solubility in binders.
Specific examples of dyes include: diarylmethane dyes; triarylmethane dyes; thiazole dyes; methine dyes such as merocyanine dyes and pyrazolone methine dyes; azomethine dyes typified by indoaniline dyes, acetophenoneazomethine dyes, pyrazoloazomethine dyes, imidazoleazomethine dyes, imidazoazomethine dyes, and pyridoneazomethine dyes; xanthene dyes; oxazine dyes; cyanomethylene dyes typified by dicyanostyrene dyes and tricyanostyrene dyes; thiazine dyes; azine dyes; acridine dyes; azo dyes such as benzeneazo dyes, pyridoneazo dyes, thiopheneazo dyes, isothiazoleazo dyes, pyrroleazo dyes, pyrraleazo dyes, imidazoleazo dyes, thiadiazoleazo dyes, triazoleazo dyes, and disazo dyes; spiropyran dyes; indolinospiropyran dyes; fluoran dyes; rhodaminelactam dyes; naphthoquinone dyes; anthraquinone dyes; and quinophthalone dyes.
In forming the dye layer, a binder may be added to a composition (a liquid composition) for dye layer formation, and, for example, a conventional resin binder may be used. Specific examples of preferred binders (resins) include: cellulosic resins such as ethylcellulose, hydroxyethylcellulose, ethylhydroxycellulose, hydroxypropylcellulose, methylcellulose, cellulose acetate, and cellulose butyrate; vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinylpyrrolidone, and polyacrylamide; polyester resins; and phenoxy resins. Among them, cellulosic resins, acetal resins, butyral resins, polyester resins, phenoxy resins and the like are particularly preferred, for example, from the viewpoints of heat resistance and transferability of dye.
Further, in the present invention, instead of the resin (binder), the following releasable graft copolymers may be used as a release agent or a binder. The releasable graft copolymers are such that at least one releasable segment selected from a polysiloxane segment, a carbon fluoride segment, a hydrocarbon fluoride segment, and a long-chain alkyl segment has been graft polymerized to the main chain of a polymer. Among them, a graft copolymer produced by grafting a polysiloxane segment onto the main chain of a polyvinyl acetal resin is particularly preferred.
The dye layer may comprise the above dye, the binder, and optionally other various additives. For example, organic fine particles, such as polyethylene wax, and inorganic fine particles may be mentioned as additives for improving the separability of the thermal transfer sheet from the image-receiving sheet and the coatability of the ink.
Formation of Dye Layer
In general, the dye layer may be formed by adding the dye, the binder, and optional additives to a suitable solvent to dissolve or disperse the ingredients and thus to prepare a liquid composition, coating the liquid composition onto a substrate, and drying the coating. Conventional coating means, such as gravure printing, screen printing, and reverse roll coating using a gravure plate, may be used for the coating. The coverage of the component for forming the dye layer (coating liquid) is 0.2 to 6.0 g/m2, preferably about 0.3 to 3.0 g/m2, on a dry basis.
4. Heat-Resistant Slip Layer
In the thermal transfer sheet according to the present invention, a heat resistant slip layer is provided mainly from the viewpoint of preventing adverse effects such as sticking caused by heat of a thermal head and cockling at the time of printing.
The heat resistant slip layer may be formed using a resin. Examples of resins usable herein include polyvinyl butyral resins, polyvinyl acetoacetal resins, polyester resins, vinyl chloride-vinyl acetate copolymers, polyether resins, polybutadiene resins, styrene-butadiene copolymers, acrylic polyols, polyurethane acrylates, polyester acrylates, polyether acrylates, epoxy acrylates, prepolymers of urethane or epoxy, nitrocellulose resins, cellulose nitrate resins, cellulose acetopropionate resins, cellulose acetate butyrate resins, cellulose acetate hydrodiene phthalate resins, cellulose acetate resins, aromatic polyamide resins, polyimide resins, polyamide-imide resins, polycarbonate resins, and chlorinated polyolefin resins.
The heat resistant slip layer may also be formed by adding a slipperiness-imparting agent to the resin, or by top-coating a slipperiness-imparting agent to the heat resistant slip layer formed of a resin. Specific examples of slipperiness-imparting agents include phosphoric esters, silicone oils, graphite powder, silicone graft polymers, fluoro graft polymers, acrylsilicone graft polymers, acrylsiloxanes, arylsiloxanes, and other silicone polymers. A preferred slipperiness-imparting agent comprises a polyol, for example, a high-molecular polyalcohol compound, a polyisocyanate compound and a phosphoric ester compound. In the present invention, the addition of a filler is more preferred.
The heat-resistant slip layer may be formed by dissolving or dispersing the resin, the slipperiness-imparting agent, and a filler in a suitable solvent to prepare a liquid composition for a heat resistant slip layer, coating the liquid composition onto the substrate sheet by forming means, such as gravure printing, screen printing, or reverse roll coating using a gravure plate, and drying the coating. The coverage of the heat-resistant slip layer is preferably 0.1 to 3.0 g/m2 on a solid basis.
Second Aspect of the Present Invention
The thermal transfer sheet according to the second aspect of the present invention has the same construction as the thermal transfer sheet according to the first aspect of the present invention, except for the adhesive layer. That is, for example, the substrate, the primer layer, the heat resistant slip layer, and the dye layer may be the same as those in the thermal transfer sheet according to the first aspect of the present invention.
Adhesive Layer
The adhesive layer in the second aspect of the present invention comprises a polyvinylpyrrolidone resin and a saccharide or a sugar alcohol. Since the saccharide or sugar alcohol is highly hygroscopic, the saccharide or sugar alcohol absorbs moisture and the moisture absorption of the polyvinylpyrrolidone resin can be significantly suppressed. Therefore, as compared with an adhesive layer formed of a polyvinylpyrrolidone resin alone, the adhesion between the dye layer and the substrate under high temperature and high humidity conditions can be improved, and abnormal transfer can be significantly suppressed.
1) Polyvinylpyrrolidone Resin
Specific examples of polyvinylpyrrolidone resins include homopolymers of vinylpyrrolidones such as N-vinyl-2-pyrrolidone and N-vinyl-4-pyrrolidone, or copolymers of thereof. In particular, polyvinylpyrrolidone resins as a straight chain polymer are preferred because the effect of improving the sensitivity in transfer in printing is high and, at the same time, the adhesive between the dye layer and the substrate is good. Preferably, the polyvinylpyrrolidon resin has a K value in a Fickencher's formula of not less than 60, and grades of K-60 to K-120 are particularly preferred. When the polyvinylpyrrolidone resin has a K value of not less than 60, the sensitivity in transfer in printing can be advantageously improved. The polyvinylpyrrolidone resin may have a number average molecular weight of about 30,000 to 280,000.
Polyvinylpyrrolidone resins may be polymers comprising not only a monomer of N-vinyl-2-pyrrolidone or N-vinyl-4-pyrrolidone but also a derivative having a substituent in a pyrrolidone ring such as N-vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-3,3,5-trimethylpyrolidone, or N-vinyl-3-benzylpyrrolidone. The adhesive layer may further comprise other resin (binder), and specific examples of other resins include polyvinyl alcohol resins and cellulose derivatives.
The addition amount of the polyvinylpyrrolidone resin is preferably about 95% by weight to 85% by weight based on the total solid content of the component for forming the adhesive layer.
2) Saccharide or Sugar Alcohol
Specific examples of saccharides include sucrose, lactose, fructose, maltose, isomaltose, maltose, maltoligosaccharide, maltodextrin, fructo-oligosaccharide, isomerized sugar, coupling sugar, galacto-oligosaccharide, and polydextrose. Specific examples of sugar alcohol include xylitol, erythritol, sortibol, mannitol, lactitol, isomaltitol, hydrogenated glucose syrup, xylo-oligosaccharide alcohol, and polydextrose reducing substance. Two or more saccharides or sugar alcohols may be used in combination. In the present invention, among the saccharides or sugar alcohols, xylitol is preferred. The adhesive layer comprising xylitol can effectively improve the adhesion between the substrate and the dye layer at room temperature or under high humidity conditions.
The addition amount of the saccharide or sugar alcohol is preferably 5% by weight to 10% by weight based on the total solid content of the adhesive layer. When the addition amount falls within the above-defined range, the adhesion between the dye layer and the substrate under high temperature and high humidity conditions can be enhanced and, consequently, unfavorable phenomena such as abnormal transfer can be prevented.
Formation of Adhesive Layer
The adhesive layer may be formed by dissolving or dispersing a polyvinylpyrrolidone resin, a saccharide or a sugar alcohol, and optionally an additive in water, an aqueous solvents such as alcohols, or an organic solvent to prepare a coating liquid and coating the coating liquid onto a substrate by conventional coating means such as gravure printing, screen printing, or reverse roll coating using a gravure plate. The coverage of the component for forming the adhesive layer (coating liquid) is about 0.05 to 0.3 g/m2 on a dry basis. When the coverage is in the above-defined range, the concaves and convexes on the substrate can be eliminated by filling with the coating to form an even surface, that is, no uncoated part occurs. As a result, an abnormal transfer phenomenon that, in the thermal transfer, the dye layer is disadvantageously transferred onto the receptive layer side of the image receiving sheet, can be effectively prevented. Further, mixing of the adhesive layer with the dye layer at the time of coating of the dye layer can be prevented, and, thus, in the thermal transfer, abnormal transfer of the receptive layer onto the dye layer side can be effectively prevented.
Third Aspect of the Present Invention
The thermal transfer sheet according to the third aspect of the present invention has the same construction as the thermal transfer sheet according to the first aspect of the present invention, except for the adhesive layer. That is, for example, the substrate, the primer layer, the heat resistant slip layer, and the dye layer may be the same as those in the thermal transfer sheet according to the first aspect of the present invention.
Adhesive Layer
The adhesive layer in the third aspect of the present invention comprises a polyvinylpyrrolidone resin and a complex forming agent. When a complex forming agent is added to the polyvinylpyrrolidone resin, the complex forming agent is bonded to the polyvinylpyrrolidone resin to from a complex of polyvinylpyrrolidone (composite). This complex (composite) is insoluble in water, and the hygroscopicity is lost. Therefore, the hygroscopic properties of the polyvinylpyrrolidone resin can be suppressed, and the hygroscopic properties of the thermal transfer sheet used under high humidity conditions can be significantly suppressed. By virtue of this, as compared with an adhesive layer formed of a polyvinylpyrrolidone resin alone, the adhesion between the dye layer and the substrate under high temperature and high humidity conditions can be improved and the abnormal transfer can be significantly suppressed.
1) Polyvinylpyrrolidone Resin
Details of the polyvinylpyrrolidone resin may be the same as those described above in connection with the second aspect of the present invention. The addition amount of the polyvinylpyrrolidone resin is preferably 99.5% by weight to 850% by weight based on the total solid content of the component for forming the adhesive layer.
2) Complex Forming Agent
The complex forming agent is added as a molecule to the end of polyvinylpyrrolidone to form a complex. The resultant complex removes the water absorption of the polyvinylpyrrolidone resin and thus can render the polyvinylpyrrolidone insoluble in water. Specific examples of complex forming agents include polyacrylic acid, tannic acid, and phenols such as resorcin and pyrogallol. The “tannic acid” generally refers to tannins obtained from nutgalls or galls. Tannins are classified into two groups, hydrolyzable tannins and condensed tannins. Hydrolyzable tannins are a group of pyrogallol tannins that are hydrolyzed with an acid, an alkali or an enzyme (tannase) into an alcohol (generally glucose) and an acid (generally gallic acid). Typical hydrolyzable tannins include gall tannins and galinut tannins. Hydrolyzable gall and gallnut tannins are preferably used. Regarding the “pyrogallol,” not only pyrogallol per se but also pyrogallol derivatives such as pyrogallol ether, pyrogallol ester, and gallic esters may also be used. Two or more of the above complex forming agents may be used in combination so far as there is no influence of interaction between the two or more complex forming agents. In the present invention, among the above complex forming agents, hydrolysable tannins and pyrogallol derivatives are preferred.
Regarding the adhesion between the substrate and the dye layer, good adhesion can be provided both at room temperature and under high humidity conditions. In the present invention, in order to prevent a deterioration in adhesion between the dye layer and the substrate due to the moisture absorption of the polyvinylpyrrolidone resin in the adhesive layer, the polyvinylpyrrolidone resin is bonded to the complex forming agent to form a complex of polyvinylpyrrolidone (composite) insoluble in water, thus rendering the polyvinylpyrrolidone nonhygroscopic. Consequently, by virtue of the copresence of the polyvinylpyrrolidone resin and the complex in the adhesive layer, the adhesion between the dye layer and the substrate can be enhanced even under a high temperature and high humidity environment, and unfavorable phenomena such as abnormal transfer can be prevented.
The addition amount of the complex forming agent is preferably 0.5% by weight to 10% by weight based on the total solid content of the component for forming the adhesive layer. When the addition amount falls within the above-defined range, the adhesion between the dye layer and the substrate under high temperature and high humidity conditions can be improved.
Formation of Adhesive Layer
The adhesive layer may be formed by mixing a polyvinylpyrrolidone resin with a complex forming agent, optionally adding additives to the mixture, and dissolving or dispersing the mixture in water, an aqueous solvent of alcohols, or an organic solvent to prepare a coating liquid, and coating the coating liquid by conventional coating means such as gravure printing, screen printing, or reverse roll coating using a gravure plate. The coverage of the adhesive layer is 0.05 to 0.3 g/m2 on a dry basis. When the coverage is in the above-defined range, the concaves and convexes on the substrate can be eliminated by filling with the coating to form an even surface, that is, no uncoated part occurs. As a result, an abnormal transfer phenomenon that, in the thermal transfer, the dye layer is disadvantageously transferred onto the receptive layer side of the image receiving sheet, can be effectively prevented. Further, mixing of the adhesive layer with the dye layer at the time of coating of the dye layer can be prevented, and, thus, in the thermal transfer, abnormal transfer of the receptive layer onto the dye layer side can be effectively prevented.
Fourth Aspect of the Present Invention
The thermal transfer sheet according to the fourth aspect of the present invention has the same construction as the thermal transfer sheet according to the first aspect of the present invention, except for the adhesive layer. That is, for example, the substrate, the primer layer, the heat resistant slip layer, and the dye layer may be the same as those in the thermal transfer sheet according to the first aspect of the present invention.
Adhesive Layer
The adhesive layer in the fourth aspect of the present invention comprises a polyvinylpyrrolidone resin and a modifying agent for modifying the resin. The addition of the modifying agent to the polyvinylpyrrolidone resin can suppress the hygroscopic properties of the polyvinylpyrrolidone resin and can significantly suppress the hygroscopic properties of the thermal transfer sheet under high humidity conditions. By virtue of this, as compared with an adhesive layer formed of a polyvinylpyrrolidone resin alone, the adhesion between the dye layer and the substrate under high temperature and high humidity conditions can be improved and the abnormal transfer can be significantly suppressed.
1) Polyvinylpyrrolidone Resin
Details of the polyvinylpyrrolidone resin may be the same as those described above in connection with the second aspect of the present invention. The addition amount of the polyvinylpyrrolidone resin is preferably 99.5% by weight to 85% by weight based on the total solid content of the component for forming the adhesive layer.
2) Modifying Agent
The modifying agent modifies the polyvinylpyrrolidone resin per se. The addition of the modifying agent can suppress the hygroscopic properties of the polyvinylpyrrolidone resin per se and can significantly improve the adhesion to the substrate. Specific examples of modifying agents usable herein include carboxymethylcellulose, cellulose acetate, cellulose acetate propionate, dibutyl tartrate, dimethyl phthalate, shellac resins and other resins. Preferred are cellulose acetate propionate and shellac resins. In the present invention, two or more of the above modifying agents may be used in combination.
The addition amount of the modifying agent is preferably 0.5% by weight to 10% by weight based on the total solid content of the component for forming the adhesive layer. When the addition amount falls within the above-defined range, the adhesion between the dye layer and the substrate under high temperature and high humidity conditions can be improved, and the abnormal transfer can be significantly suppressed.
Formation of Adhesive Layer
The adhesive layer may be formed by mixing a polyvinylpyrrolidone resin with a modifying agent, optionally adding additives to the mixture, dissolving or dispersing the mixture in water, an aqueous solvents such as alcohols, or an organic solvent to prepare a coating liquid and coating the coating liquid onto a substrate by conventional coating means such as gravure printing, screen printing, or reverse roll coating using a gravure plate. The coverage of the adhesive layer is about 0.05 to 0.3 g/m2 on a dry basis. When the coverage is in the above-defined range, the concaves and convexes on the substrate can be eliminated by filling with the coating to form an even surface, that is, no uncoated part occurs. As a result, an abnormal transfer phenomenon that, in the thermal transfer, the dye layer is disadvantageously transferred onto the receptive layer side of the image receiving sheet, can be effectively prevented. Further, mixing of the adhesive layer with the dye layer at the time of coating of the dye layer can be prevented, and, thus, in the thermal transfer, abnormal transfer of the receptive layer onto the dye layer side can be effectively prevented.
Fifth Aspect of the Present Invention
The thermal transfer sheet according to the fifth aspect of the present invention has the same construction as the thermal transfer sheet according to the first aspect of the present invention, except for the adhesive layer. That is, for example, the substrate, the primer layer and the dye layer may be the same as those in the thermal transfer sheet according to the first aspect of the present invention. Further, in the fifth aspect of the present invention, as with the first aspect of the present invention, a heat resistant slip layer may be formed. In this case, the construction and formation of the heat resistant slip layer may be as described above in connection with the first aspect of the present invention.
Adhesive Layer
The adhesive layer according to the fifth aspect of the present invention comprises a polyvinylpyrrolidone resin and at least one component selected from the group (A) and at least one component selected from the group (B). The addition of at least one component selected from the group (A) and at least one component selected from the group (B) to the polyvinylpyrrolidone resin can suppress the hygroscopic properties of the polyvinylpyrrolidone resin and can significantly suppress the hygroscopic properties of the thermal transfer sheet used under high humidity conditions. Therefore, as compared with an adhesive layer formed of a polyvinylpyrrolidone alone, the adhesion between the dye layer and the substrate under high temperature and high humidity conditions can be improved, and the abnormal transfer can be significantly suppressed. In particular, when a mixture of a polyurethane resin and/or an acrylic polyol resin in the group (A) with an isocyanate, a blocked isocyanate and/or an aluminum chelating agent in the group (B) is added, the polyurethane resin and acrylic polyol resin in the group (A) are cured. Therefore, a significant level of improvement in adhesive strength and water resistance of the thermal transfer sheet can be realized, and abnormal transfer in high energy printing can be suppressed.
1) Polyvinylpyrrolidone Resin
Specific examples of polyvinylpyrrolidone resins include homopolymers of vinylpyrrolidones such as N-vinyl-2-pyrrolidone and N-vinyl-4-pyrrolidone, or copolymers of thereof. The polyvinylpyrrolidone resin suitable for use in the present invention has a molecular weight in the range of 1000 to 3500 (×103) as measured by GPC and has a K value in a Fickencher's formula in the range of 80 to 130.
In an embodiment of the present invention, a modification product of a polyvinylpyrrolidone resin may be contained in combination with the polyvinylpyrrolidone resin. In this case, one of the modification products of polyvinylpyrrolidone used is a copolymer of vinylpyrrolidone with other copolymerizable monomer. The modification product is added from the viewpoint of lowering the water absorption of a coating film of polyvinylpyrrolidone to suppress a lowering in adhesion under a high temperature and high humidity environment. Copolymerizable monomers include, for example, vinyl monomers such as styrene, vinyl acetate, acrylic esters, acrylonitrile, maleic anhydride, vinyl chloride (fluoride), and vinylidene chloride (fluoride or cyanide). A copolymer produced by radical copolymerization of the vinyl monomer with vinylpyrrolidone may be used. Further, block copolymers and graft copolymers between resins, such as polyester, polycarbonate, polyurethane, epoxy, acetal, butyral, formal, phenoxy, or cellulose resins, and polyvinylpyrrolidone may also be used. In order to modify the properties of polyvinylpyrrolidone, another modification product, that is, a material prepared by crosslinking a part of polyvinylpyrrolidone may also be used. The modification product suitable for use in the present invention has a molecular weight in the range of 100 to 3000 (×103) as measured by GPC.
The addition amount of the polyvinylpyrrolidone resin is 98% by weight, to 60% by weight, preferably 98% by weight to 85% by weight, based on the total solid content of the component for forming the adhesive layer.
When the modification product of the polyvinylpyrrolidone resin is incorporated, the addition amount of the modification product is 20 to 80% by weight, preferably 30 to 70% by weight, based on the polyvinylpyrrolidone resin. When the addition amount falls within the above-defined range, the water absorption of the polyvinylpyrrolidone resin can be suppressed, and the adhesion at room temperature can be improved.
Group (A)
The polyurethane resin and the acrylic polyol resin may be conventional materials such as solid form or organic solution dilution type. In this case, however, the polyurethane resin and acrylic polyol resin are soluble in a mixed solvent composed of methyl ethyl ketone (MEK) and isopropyl alcohol (IPA) at a weight ratio 1:1 (MEK/IPA=1/1) and, even when diluted to a solid content of 5% by weight, do not gel. The addition of the above polyurethane resin or acrylic polyol resin can realize excellent suitability for coating.
In the present invention, preferably, the polyurethane resin and the acrylic polyol resin can be crosslinked or cured with an isocyanate, a blocked isocyanate, or an aluminum chelating agent in the group (B). The effect of the present invention can be attained by using the above compounds as a mixed solution with the polyvinylpyrrolidone resin or a mixture of the polyvinylpyrrolidone resin and the modification product of the polyvinylpyrrolidone resin. The polyurethane resin usable in the present invention may be a commercially available product, and examples thereof include SANPRENE IB-114B (manufactured by Sanyo Chemical Industries, Ltd.). Examples of commercially available products of the acrylic polyol resin include Acrydic A-801-P (manufactured by Dainippon Ink and Chemicals, Inc.). The acrylic polyol resin is a polymer comprising hydroxyl group-containing (meth)acrylic monomer units, for example, poly(hydroxyethyl methacrylate) and has, as a solid, an acid value of about 1 to 15 and a hydroxyl value of about 20 to 150.
The addition amount of at least one component selected from the group consisting of polyurethane resins and acrylic polyol resins is 1 to 30% by weight, preferably 1 to 100% by weight, based on the total solid content of the component for forming the adhesive layer. When the addition amount falls within the above-defined range, the function as the adhesive component is satisfactory. Further, as compared with an adhesive layer formed of a polyvinylpyrrolidone resin alone, the print density can be improved.
Group (B)
The isocyanate, blocked isocyanate, and aluminum chelating agent may be conventional materials such as solid form or organic solution dilution type. In this case, however, the isocyanate, blocked isocyanate, and aluminum chelating agent are soluble in a mixed solvent composed of methyl ethyl ketone (MEK) and isopropyl alcohol (IPA) at a weight ratio 1:1 (MEK/IPA=1/1) and, even when diluted to a solid content of 5% by weight, do not gel. The addition of the isocyanate, blocked isocyanate, and aluminum chelating agent can realize excellent suitability for coating.
Specific examples of isocyanates include hexamethylene diisocyanate (HDI), xylene diisocyate (XDI), methylene diisocyanate (MDI), isophorone diisocyanate (IPDI), hydrogenated xylene diisocyanate (H6XDI), and dimmers or trimers of these isocvanate monomers, for example, isocyanurate compounds, adduct compounds, and biuret compounds. Specific examples of blocked isocyanates include those in which an isocynate group has been masked, for example, with oxime or lactam. Specific examples of aluminum chelating agents include aluminum salts of ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), dihydroxyethylethylenediaminediacetic acid (DHEDDA) and the like. The compounds belonging to the group (B) may be commercially available products, and examples thereof include Takenate A-14 (manufactured by MITSUI TAKEDA CHEMICALS, INC.) (isocyanate), NK ASSIST IS-80D (manufactured by Nicca Chemical Co., Ltd.) (blocked isocyanate), and DICNATE AL500 (manufactured by Dainippon Ink and Chemicals, Inc.) (aluminum chelating agent).
The addition amount of at least one component selected from the group consisting of isocyanates, blocked isocyanates, and aluminum chelating agents is 1 to 10% by weight, preferably 1 to 5% by weight, based on the total solid content of the component for forming the adhesive layer. When the addition amount falls within the above-defined range, the function of curing the polyurethane resin and the acrylic polyol resin is satisfactory and the stability of the coating liquid is good.
Optional Components
In order to improve the function as the adhesive layer, optional components in addition to the above components, may be added to the adhesive layer. Specific examples of optional components include polyester resins, vinyl resins such as polyacrylic ester resins, polyvinyl acetate resins, styrene acrylate resins, polyacrylamide resins, polyamide resins, polyether resins, polystyrene resins, polyethylene resins, polypropylene resins, polyvinyl chloride resins and vinyl-chloride-vinyl acetate copolymer resins, and ethylene-vinyl acetate copolymer resins, and polyvinylacetal resins such as polyvinylacetoacetal and polyvinylbutyral. Among them, polyester resins and acrylic resins are preferred from the viewpoint of improving the adhesion.
The addition amount of the optional component is preferably 1 to 10% by weight based on the total solid content of the component for forming the adhesive layer. When the addition amount falls within the above-defined range, the polyvinylpyrrolidone resin-derived print density can be improved. Further, the application of the adhesive layer to substrates not subjected to corona discharge treatment or other treatment is also possible.
Such other optional components include, for example, wettability improvers, fluorescent brighteners, and various fillers.
Formation of Adhesive Layer
The adhesive layer may be formed by mixing the polyvinylpyrrolidone resin (optionally in combination with a modification product of polyvinylpyrrolidone resin) with the component in the group (A), the component in the group (B), and optional components, dissolving or dispersing the mixture in an organic solvent or an aqueous solvent to prepare a coating liquid, and coating the coating liquid by conventional coating means such as gravure printing, screen printing, or reverse roll coating using a gravure plate. Regarding the solvent, a mixed solvent composed of MEK and IPA is suitable because the mixed solvent can well dissolve the above materials and can easily control the viscosity in the coating. In the preparation of the coating liquid, when the total solid content is brought to 3 to 7% by weight, good suitability for coating can be realized. When the total solid content falls within the above-described range, the suitability for coating is improved and the viscosity can be maintained at a proper value. As a result, the suitability for coating in gravure printing can be significantly improved. Therefore, also for the polyurethane resin and the acrylic polyol resin, materials, which, when diluted to a solid content of about 5% by weight with a mixed solvent composed of MEK and IPA, do not gel, are preferably selected. Further, also for the isocyanate, blocked isocyanate, and aluminum chelating agent, materials, which, when diluted to a solid content of about 5% by weight with a mixed solvent composed of MEK and IPA, do not gel, should be selected.
The adhesive layer may be coated as a blotted image onto the whole area on the dye layer coating side of the substrate, or alternatively may be formed in a pattern form only between the substrate and the dye layer. The coverage of the adhesive layer on a dry basis is 0.01 to 3.0 g/m2, preferably 0.05 to 0.3 g/m2. When the coverage of the adhesive layer falls within the above-defined range, the concaves and convexes on the substrate can be eliminated by filling with the adhesive layer and any uncoated part does not occur. Therefore, in the thermal transfer, abnormal transfer in which the dye layer is transferred to an image receiving sheet on its receptive layer side can be effectively prevented. Further, mixing of the adhesive layer with the dye layer in the coating of the dye layer can be prevented, and abnormal transfer, in which the receptive layer is transferred to the dye layer side at the time of thermal transfer, can be effectively prevented.
The following Examples further illustrate the contents of the first to fifth aspects of the present invention. However, the invention is not to be construed as being limited thereto. In the Examples (Comparative Examples), parts or % is by weight unless otherwise specified.
First Aspect of the Present Invention
A 4.5 μm-thick untreated polyethylene terephthalate (PET) film (DIAFOIL K 880, manufactured by Mitsubishi Polyester Film Co., Ltd.) was provided as a substrate. A liquid composition A1 having the following composition for an adhesive layer was gravure coated onto the PET film at a coverage of 0.03 g/m2 on a dry basis, and the coating was dried at 110° C. for one min to form an adhesive layer. A liquid composition A having the following composition for a dye layer was then gravure coated on the adhesive layer at a coverage of 0.8 g/m2 on a dry basis, and the coating was dried to form a dye layer. Thus, a thermal transfer sheet of Example A1 was prepared. In this case, a liquid composition A having the following composition for a heat resistant slip layer was previously gravure coated on the other side of the substrate at a coverage of 1.0 g/m2 on a dry basis, and the coating was dried to form a heat resistant slip layer.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. The liquid composition for an adhesive layer as used in Example A1 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.05 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A2 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer used in Example A1 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.1 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A3 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer used in Example A1 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.2 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A4 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer used in Example A1 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.25 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A5 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer used in Example A1 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.35 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A6 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A2 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A7 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A3 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.03 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A8 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer used in Example A8 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.05 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A9 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer used in Example A8 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.2 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A10 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer used in Example A8 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.35 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A11 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A4 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.2 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A12 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A5 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A13 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A6 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.03 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A14 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer used in Example A14 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.05 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A15 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer used in Example A14 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.2 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A16 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer used in Example A14 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.35 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A17 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A7 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A18 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A8 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A19 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A9 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A20 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A10 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A21 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A11 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A22 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A12 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A23 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A13 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Example A24 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A coating liquid A14 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example A1. Thus, a thermal transfer sheet of Comparative Example A1 was prepared.
The same substrate of PET film as used in Example A1 was provided. A heat resistant slip layer as described in Example A1 was previously formed on the other side of the substrate. A dye layer was formed onto the substrate on its side remote from the heat resistant slip layer in the same manner as in Example A1, except that the dye layer was formed directly onto the substrate without providing the adhesive layer. Thus, a thermal transfer sheet of Comparative Example A2 was prepared.
Evaluation Test A
The thermal transfer sheets of Example A and Comparative Example A were evaluated for heat-resistant adhesion at room temperature and under high-temperature and high-humidity conditions and adhesion to an image-receiving sheet by the following methods.
(Evaluation 1: Heat Resistant Adhesion 1)
Each of the thermal transfer sheets of Example A and Comparative Example A as a sample was applied onto a mount so that the dye layer surface faced upward, that is, the mount was brought into contact with the heat resistant slip layer. A reference ribbon 1 (an assembly comprising a dye layer, which is the same as that in the sample, provided directly on an easy-adhesion treated PET film of DIAFOIL K230E manufactured by MITSUBISHI POLYESTER FILM CORPORATION as a substrate) corresponding to the sample was applied onto the identical mount at its position different from the position of the sample so that the surface of the dye layer faced upward. Each mount was folded back so that dye layer surface in the sample and the dye layer surface in the reference ribbon were put on top of and brought into contact with each other. In this state, heat sealing was carried out under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec, followed by separation. The assembly was then visually inspected for residual dye layer (undesired transfer of dye layer) in each of the sample and the reference ribbon 1. The results were evaluated according to the following criteria. In this case, the heat resistant adhesion test was carried out by the following two testing methods. In one of the testing methods, the heat sealing was carried out in such a state that both the thermal transfer sheets of Example A and Comparative Example A as samples and the reference ribbon 1 were allowed to stand at room temperature. In the other testing method, the heat sealing was carried out after both the sample thermal transfer sheets and the reference ribbon 1 were allowed to stand under an environment of 40° C. and 90% RH for 16 hr.
Evaluation Criteria
◯: The area of the dye layer remaining on the sample side is larger than the area of the dye layer remaining on the reference ribbon side.
Δ: The area of the dye layer remaining on the sample side is equal to the area of the dye layer remaining on the reference ribbon side.
x: The area of the dye layer remaining on the sample side is smaller than the area of the dye layer remaining on the reference ribbon side.
(Evaluation 2: Heat Resistant Adhesion 2)
Each of the thermal transfer sheets of Example A and Comparative Example A as a sample was applied onto a mount so that the dye layer surface faced upward, that is, the mount was brought into contact with the heat resistant slip layer. A reference ribbon 2 (an assembly comprising a dye layer, which is the same as that in the sample, provided on a substrate comprising an adhesive layer formed of a polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) (the same as the adhesive layer in Comparative Example A1) provided at a coverage of 0.06 g/m2 on a dry basis on a surface of a PET film of DIAFOIL K880 manufactured by MITSUBISHI POLYESTER FILM CORPORATION) corresponding to the sample was applied onto the identical mount at its position different from the position of the sample so that the surface of the dye layer faced upward. Each mount was folded back so that dye layer surface in the sample and the dye layer surface in the reference ribbon were put on top of and brought into contact with each other. In this state, heat sealing was carried out under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec, followed by separation. The assembly was then visually inspected for residual dye layer (undesired transfer of dye layer) in each of the sample and the reference ribbon 2. The results were evaluated according to the same criteria as the heat resistant adhesion 1. In this case, the heat resistant adhesion test was carried out by the following two testing methods. In one of the testing methods, the heat sealing was carried out in such a state that both the thermal transfer sheets of Example A and Comparative Example A as samples and the reference ribbon 2 were allowed to stand at room temperature. In the other testing method, the heat sealing was carried out after both the sample thermal transfer sheets and the reference ribbon 2 were allowed to stand under an environment of 40° C. and 90% RH for 16 hr.
(Adhesion to Image Receiving Sheet)
Each of the thermal transfer sheets of Example A and Comparative Example A and a specialty standard set of an image receiving sheet for a digital color printer P-200, manufactured by Olympus Optical Co., LTD. were put on top of each other so that the dye layer surface in the thermal transfer sheet was brought into contact with the image receiving surface in the image receiving sheet. The assembly was heat sealed under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec. Thereafter, both the sheets were separated from each other and were visually inspected for the state of separation between the dye layer in the sample and the image receiving layer in the image receiving sheet, and the results were evaluated according to the following criteria. In this case, the heat sealing of the thermal transfer sheet and the image receiving sheet was carried out in such a state that these sheets were allowed to stand at room temperature.
Evaluation Criteria
◯: No abnormal transfer of image receiving layer onto dye layer side took place.
x: Abnormal transfer of image receiving layer onto dye layer side took place.
The results of the evaluation of each item will be shown in Table 1 below.
Second Aspect of the Present Invention
A 4.5 μm-thick untreated polyethylene terephthalate (PET) film (DIAFOIL K 880, manufactured by Mitsubishi Polyester Film Co., Ltd.) was provided as a substrate. A liquid composition B1 having the following composition for an adhesive layer was gravure coated onto the PET film at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried at 110° C. for one min to form an adhesive layer. A liquid composition B having the following composition for a dye layer was then gravure coated on the adhesive layer at a coverage of 0.8 g/m2 on a dry basis, and the coating was dried to form a dye layer. Thus, a thermal transfer sheet of Example B1 was prepared. In this case, a liquid composition B having the following composition for a heat resistant slip layer was previously gravure coated on the other side of the substrate at a coverage of 1.0 g/m2 on a dry basis, and the coating was dried to form a heat resistant slip layer.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B2 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B2 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A coating liquid B3 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B3 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B4 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B4 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B5 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B5 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B6 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B6 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B7 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.05 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B7 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.2 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B8 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B8 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B9 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B9 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B10 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B10 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B11 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B11 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B12 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B12 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B13 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B13 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B14 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B14 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B15 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B15 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B16 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. The liquid composition for an adhesive layer as used in Example B7 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.03 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B17 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. The liquid composition for an adhesive layer as used in Example B7 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.35 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Comparative Example B18 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B16 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Example B19 was prepared.
The same substrate of PET film as used in Example B1 was provided. A heat resistant slip layer as described in Example B1 was previously formed on the other side of the substrate. A liquid composition B17 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example B1. Thus, a thermal transfer sheet of Comparative Example B1 was prepared.
Evaluation Test B
The thermal transfer sheets of Example B and Comparative Example B were evaluated for heat-resistant adhesion at room temperature and under high-temperature and high-humidity conditions and adhesion to an image-receiving sheet by the following methods.
(Heat Resistant Adhesion 1)
Each of the thermal transfer sheets of Example B and Comparative Example B as a sample was applied onto a mount so that the dye layer surface faced upward, that is, the mount was brought into contact with the heat resistant slip layer. A reference ribbon 1 (an assembly comprising a dye layer, which is the same as that in the sample, provided directly on an easy-adhesion treated PET film of DIAFOIL K230E manufactured by MITSUBISHI POLYESTER FILM CORPORATION as a substrate) corresponding to the sample was applied onto the identical mount at its position different from the position of the sample so that the surface of the dye layer faced upward. Each mount was folded back so that dye layer surface in the sample and the dye layer surface in the reference ribbon were put on top of and brought into contact with each other. In this state, heat sealing was carried out under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec, followed by separation. The assembly was then visually inspected for residual dye layer (undesired transfer of dye layer) in each of the sample and the reference ribbon 1. The results were evaluated according to the following criteria. In this case, the heat resistant adhesion test was carried out by the following two testing methods. In one of the testing methods, the heat sealing was carried out in such a state that both the thermal transfer sheets of Example B and Comparative Example B as samples and the reference ribbon 1 were allowed to stand at room temperature. In the other testing method, the heat sealing was carried out after both the sample thermal transfer sheets and the reference ribbon 1 were allowed to stand under an environment of 40° C. and 90% RH for 16 hr.
Evaluation Criteria
◯: The area of the dye layer remaining on the sample side is larger than the area of the dye layer remaining on the reference ribbon side.
Δ: The area of the dye layer remaining on the sample side is equal to the area of the dye layer remaining on the reference ribbon side.
x: The area of the dye layer remaining on the sample side is smaller than the area of the dye layer remaining on the reference ribbon side.
(Heat Resistant Adhesion 2)
Each of the thermal transfer sheets of Example B and Comparative Example B as a sample was applied onto a mount so that the dye layer surface faced upward, that is, the mount was brought into contact with the heat resistant slip layer. A reference ribbon 2 (an assembly comprising a dye layer, which is the same as that in the sample, provided on a substrate comprising an adhesive layer formed of a polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) (the same as the adhesive layer in Comparative Example B1) provided at a coverage of 0.06 g/m2 on a dry basis on a surface of a PET film of DIAFOIL K880 manufactured by MITSUBISHI POLYESTER FILM CORPORATION as a substrate) corresponding to the sample was applied onto the identical mount at its position different from the position of the sample so that the surface of the dye layer faced upward. Each mount was folded back so that dye layer surface in the sample and the dye layer surface in the reference ribbon were put on top of and brought into contact with each other. In this state, heat sealing was carried out under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec, followed by separation. The assembly was then visually inspected for residual dye layer (undesired transfer of dye layer) in each of the sample and the reference ribbon 2. The results were evaluated according to the same criteria as the heat resistant adhesion 1. In this case, the heat resistant adhesion test was carried out by the following two testing methods. In one of the testing methods, the heat sealing was carried out in such a state that both the thermal transfer sheets of Example B and Comparative Example B as samples and the reference ribbon 2 were allowed to stand at room temperature. In the other testing method, the heat sealing was carried out after both the sample thermal transfer sheets and the reference ribbon 2 were allowed to stand under an environment of 40° C. and 90% RH for 16 hr.
(Adhesion to Image Receiving Sheet)
Each of the thermal transfer sheets of Example B and Comparative Example B and a specialty standard set of an image receiving sheet for a digital color printer P-200, manufactured by Olympus Optical Co., LTD. were put on top of each other so that the dye layer surface in the thermal transfer sheet was brought into contact with the image receiving surface in the image receiving sheet. The assembly was heat sealed under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec. Thereafter, both the sheets were separated from each other and were visually inspected for the state of separation between the dye layer in the sample and the image receiving layer in the image receiving sheet, and the results were evaluated according to the following criteria. In this case, the heat sealing of the thermal transfer sheet and the image receiving sheet was carried out in such a state that these sheets were allowed to stand at room temperature.
Evaluation Criteria
◯: No abnormal transfer of image receiving layer onto dye layer side took place.
x: Abnormal transfer of image receiving layer onto dye layer side took place.
The results of evaluation of each item will be shown in Table 2 below
Third Aspect of the Present Invention
A 4.5 μm-thick untreated polyethylene terephthalate (PET) film (DIAFOIL K 880, manufactured by Mitsubishi Polyester Film Co., Ltd.) was provided as a substrate. A liquid composition C1 having the following composition for an adhesive layer was gravure coated onto the PET film at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried at 110° C. for one min to form an adhesive layer. A liquid composition C having the following composition for a dye layer was then gravure coated on the adhesive layer at a coverage of 0.8 g/m2 on a dry basis, and the coating was dried to form a dye layer. Thus, a thermal transfer sheet of Example C1 was prepared. In this case, a liquid composition C having the following composition for a heat resistant slip layer was previously gravure coated on the other side of the substrate at a coverage of 1.0 g/m2 on a dry basis, and the coating was dried to form a heat resistant slip layer.
The same substrate of PET film as used in Example C1 was provided. A heat resistant slip layer as described in Example C1 was previously formed on the other side of the substrate. A liquid composition C2 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example C1. Thus, a thermal transfer sheet of Example C2 was prepared.
The same substrate of PET film as used in Example C1 was provided. A heat resistant slip layer as described in Example C1 was previously formed on the other side of the substrate. A liquid composition C3 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example C1. Thus, a thermal transfer sheet of Example C3 was prepared.
The same substrate of PET film as used in Example C1 was provided. A heat resistant slip layer as described in Example C1 was previously formed on the other side of the substrate. A liquid composition C4 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example C1. Thus, a thermal transfer sheet of Example C4 was prepared.
The same substrate of PET film as used in Example C1 was provided. A heat resistant slip layer as described in Example C1 was previously formed on the other side of the substrate. A liquid composition C5 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.05 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example C1. Thus, a thermal transfer sheet of Example C5 was prepared.
The same substrate of PET film as used in Example C1 was provided. A heat resistant slip layer as described in Example C1 was previously formed on the other side of the substrate. The liquid composition for an adhesive layer as used in Example C5 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.2 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example C1. Thus, a thermal transfer sheet of Example C6 was prepared.
The same substrate of PET film as used in Example C1 was provided. A heat resistant slip layer as described in Example C1 was previously formed on the other side of the substrate. A liquid composition C6 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example C1. Thus, a thermal transfer sheet of Example C7 was prepared.
The same substrate of PET film as used in Example C1 was provided. A heat resistant slip layer as described in Example C1 was previously formed on the other side of the substrate. A liquid composition C7 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example C1. Thus, a thermal transfer sheet of Example C8 was prepared.
The same substrate of PET film as used in Example C1 was provided. A heat resistant slip layer as described in Example C1 was previously formed on the other side of the substrate. The liquid composition for an adhesive layer as used in Example C5 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.03 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example C1. Thus, a thermal transfer sheet of Example C9 was prepared.
The same substrate of PET film as used in Example C1 was provided. A heat resistant slip layer as described in Example C1 was previously formed on the other side of the substrate. The liquid composition for an adhesive layer as used in Example C5 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.35 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example C1. Thus, a thermal transfer sheet of Example C10 was prepared.
The same substrate of PET film as used in Example C1 was provided. A heat resistant slip layer as described in Example C1 was previously formed on the other side of the substrate. A liquid composition C8 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example C1. Thus, a thermal transfer sheet of Example C11 was prepared.
The same substrate of PET film as used in Example C1 was provided. A heat resistant slip layer as described in Example C1 was previously formed on the other side of the substrate. A liquid composition C9 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example C1. Thus, a thermal transfer sheet of Comparative Example C1 was prepared.
Evaluation Test C
The thermal transfer sheets of Example C and Comparative Example C were evaluated for heat-resistant adhesion at room temperature and under high-temperature and high-humidity conditions and adhesion to an image-receiving sheet by the following methods.
(Heat Resistant Adhesion 1)
Each of the thermal transfer sheets of Example C and Comparative Example C as a sample was applied onto a mount so that the dye layer surface faced upward, that is, the mount was brought into contact with the heat resistant slip layer. A reference ribbon 1 (an assembly comprising a dye layer, which is the same as that in the sample, provided directly on an easy-adhesion treated PET film of DIAFOIL K230E manufactured by MITSUBISHI POLYESTER FILM CORPORATION as a substrate) corresponding to the sample was applied onto the identical mount at its position different from the position of the sample so that the surface of the dye layer faced upward. Each mount was folded back so that dye layer surface in the sample and the dye layer surface in the reference ribbon were put on top of and brought into contact with each other. In this state, heat sealing was carried out under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec, followed by separation. The assembly was then visually inspected for residual dye layer (undesired transfer of dye layer) in each of the sample and the reference ribbon 1. The results were evaluated according to the following criteria. In this case, the heat resistant adhesion test was carried out by the following two testing methods. In one of the testing methods, the heat sealing was carried out in such a state that both the thermal transfer sheets of Example C and Comparative Example C as samples and the reference ribbon 1 were allowed to stand at room temperature. In the other testing method, the heat sealing was carried out after both the sample thermal transfer sheets and the reference ribbon 1 were allowed to stand under an environment of 40° C. and 90% RH for 16 hr.
Evaluation Criteria
◯: The area of the dye layer remaining on the sample side is larger than the area of the dye layer remaining on the reference ribbon side.
Δ: The area of the dye layer remaining on the sample side is equal to the area of the dye layer remaining on the reference ribbon side.
x: The area of the dye layer remaining on the sample side is smaller than the area of the dye layer remaining on the reference ribbon side.
(Heat Resistant Adhesion 2)
Each of the thermal transfer sheets of Example C and Comparative Example C as a sample was applied onto a mount so that the dye layer surface faced upward, that is, the mount was brought into contact with the heat resistant slip layer. A reference ribbon 2 (an assembly comprising a dye layer, which is the same as that in the sample, provided on a substrate comprising an adhesive layer formed of a polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) (the same as the adhesive layer in Comparative Example C1) provided at a coverage of 0.06 g/m2 on a dry basis on a surface of a PET film of DIAFOIL K880 manufactured by MITSUBISHI POLYESTER FILM CORPORATION as a substrate) corresponding to the sample was applied onto the identical mount at its position different from the position of the sample so that the surface of the dye layer faced upward. Each mount was folded back so that dye layer surface in the sample and the dye layer surface in the reference ribbon were put on top of and brought into contact with each other. In this state, heat sealing was carried out under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec, followed by separation. The assembly was then visually inspected for residual dye layer (undesired transfer of dye layer) in each of the sample and the reference ribbon 2. The results were evaluated according to the same criteria as the heat resistant adhesion 1. In this case, the heat resistant adhesion test was carried out by the following two testing methods. In one of the testing methods, the heat sealing was carried out in such a state that both the thermal transfer sheets of Example C and Comparative Example C as samples and the reference ribbon 2 were allowed to stand at room temperature. In the other testing method, the heat sealing was carried out after both the sample thermal transfer sheets and the reference ribbon 2 were allowed to stand under an environment of 40° C. and 90% RH for 16 hr.
(Adhesion to Image Receiving Sheet)
Each of the thermal transfer sheets of Example C and Comparative Example C and a specialty standard set of an image receiving sheet for a digital color printer P-200, manufactured by Olympus Optical Co., LTD. were put on top of each other so that the dye layer surface in the thermal transfer sheet was brought into contact with the image receiving surface in the image receiving sheet. The assembly was heat sealed under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec. Thereafter, both the sheets were separated from each other and were visually inspected for the state of separation between the dye layer in the sample and the image receiving layer in the image receiving sheet, and the results were evaluated according to the following criteria. In this case, the heat sealing of the thermal transfer sheet and the image receiving sheet was carried out in such a state that these sheets were allowed to stand at room temperature.
Evaluation Criteria
◯: No abnormal transfer of image receiving layer onto dye layer side took place.
x: Abnormal transfer of image receiving layer onto dye layer side took place.
The results of evaluation of each item will be shown in Table 3 below
Fourth Aspect of the Present Invention
A 4.5 μm-thick untreated polyethylene terephthalate (PET) film (DIAFOIL K 880, manufactured by Mitsubishi Polyester Film Co., Ltd.) was provided as a substrate. A liquid composition D1 having the following composition for an adhesive layer was gravure coated onto the PET film at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried at 110° C. for one min to form an adhesive layer. A liquid composition D having the following composition for a dye layer was then gravure coated on the adhesive layer at a coverage of 0.8 g/m2 on a dry basis, and the coating was dried to form a dye layer. Thus, a thermal transfer sheet of Example D1 was prepared. In this case, a liquid composition D having the following composition for a heat resistant slip layer was previously gravure coated on the other side of the substrate at a coverage of 1.0 g/m2 on a dry basis, and the coating was dried to form a heat resistant slip layer.
The same substrate of PET film as used in Example D1 was provided. A heat resistant slip layer as described in Example D1 was previously formed on the other side of the substrate. A coating liquid D2 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example D1. Thus, a thermal transfer sheet of Example D2 was prepared.
The same substrate of PET film as used in Example D1 was provided. A heat resistant slip layer as described in Example D1 was previously formed on the other side of the substrate. A coating liquid D3 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example D1. Thus, a thermal transfer sheet of Example D3 was prepared.
The same substrate of PET film as used in Example D1 was provided. A heat resistant slip layer as described in Example D1 was previously formed on the other side of the substrate. A coating liquid D4 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example D1. Thus, a thermal transfer sheet of Example D4 was prepared.
The same substrate of PET film as used in Example D1 was provided. A heat resistant slip layer as described in Example D1 was previously formed on the other side of the substrate. A coating liquid D5 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.05 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example D1. Thus, a thermal transfer sheet of Example D5 was prepared.
The same substrate of PET film as used in Example D1 was provided. A heat resistant slip layer as described in Example D1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer as used in Example D5 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.2 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example D1. Thus, a thermal transfer sheet of Example D6 was prepared.
The same substrate of PET film as used in Example D1 was provided. A heat resistant slip layer as described in Example D1 was previously formed on the other side of the substrate. A coating liquid D6 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example D1. Thus, a thermal transfer sheet of Example D7 was prepared.
The same substrate of PET film as used in Example D1 was provided. A heat resistant slip layer as described in Example D1 was previously formed on the other side of the substrate. A coating liquid D7 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example D1. Thus, a thermal transfer sheet of Example D8 was prepared.
The same substrate of PET film as used in Example D1 was provided. A heat resistant slip layer as described in Example D1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer as used in Example D5 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.03 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example D1. Thus, a thermal transfer sheet of Example D9 was prepared.
The same substrate of PET film as used in Example D1 was provided. A heat resistant slip layer as described in Example D1 was previously formed on the other side of the substrate. The coating liquid for an adhesive layer as used in Example D5 was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.35 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example D1. Thus, a thermal transfer sheet of Example D10 was prepared.
The same substrate of PET film as used in Example D1 was provided. A heat resistant slip layer as described in Example D1 was previously formed on the other side of the substrate. A coating liquid D8 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example D1. Thus, a thermal transfer sheet of Example D11 was prepared.
The same substrate of PET film as used in Example D1 was provided. A heat resistant slip layer as described in Example D1 was previously formed on the other side of the substrate. A coating liquid D9 for an adhesive layer having the following composition was gravure coated onto the substrate on its side remote from the heat resistant slip layer at a coverage of 0.06 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A dye layer was formed on the adhesive layer in the same manner as in Example D1. Thus, a thermal transfer sheet of Comparative Example D1 was prepared.
Evaluation Test D
The thermal transfer sheets of Example D and Comparative Example D were evaluated for heat-resistant adhesion at room temperature and under high-temperature and high-humidity conditions and adhesion to an image-receiving sheet by the following methods.
(Heat Resistant Adhesion 1)
Each of the thermal transfer sheets of Example D and Comparative Example D as a sample was applied onto a mount so that the dye layer surface faced upward, that is, the mount was brought into contact with the heat resistant slip layer. A reference ribbon 1 (an assembly comprising a dye layer, which is the same as that in the sample, provided directly on an easy-adhesion treated PET film of DIAFOIL K230E manufactured by MITSUBISHI POLYESTER FILM CORPORATION as a substrate) corresponding to the sample was applied onto the identical mount at its position different from the position of the sample so that the surface of the dye layer faced upward. Each mount was folded back so that dye layer surface in the sample and the dye layer surface in the reference ribbon were put on top of and brought into contact with each other. In this state, heat sealing was carried out under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec, followed by separation. The assembly was then visually inspected for residual dye layer (undesired transfer of dye layer) in each of the sample and the reference ribbon 1. The results were evaluated according to the following criteria. In this case, the heat resistant adhesion test was carried out by the following two testing methods. In one of the testing methods, the heat sealing was carried out in such a state that both the thermal transfer sheets of Example D and Comparative Example D as samples and the reference ribbon 1 were allowed to stand at room temperature. In the other testing method, the heat sealing was carried out after both the sample thermal transfer sheets and the reference ribbon 1 were allowed to stand under an environment of 40° C. and 90% RH for 16 hr.
Evaluation Criteria
◯: The area of the dye layer remaining on the sample side is larger than the area of the dye layer remaining on the reference ribbon side.
Δ: The area of the dye layer remaining on the sample side is equal to the area of the dye layer remaining on the reference ribbon side.
x: The area of the dye layer remaining on the sample side is smaller than the area of the dye layer remaining on the reference ribbon side.
(Heat Resistant Adhesion 2)
Each of the thermal transfer sheets of Example D and Comparative Example D as a sample was applied onto a mount so that the dye layer surface faced upward, that is, the mount was brought into contact with the heat resistant slip layer. A reference ribbon 2 (an assembly comprising a dye layer, which is the same as that in the sample, provided on a substrate comprising an adhesive layer formed of a polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) (the same as the adhesive layer in Comparative Example D1) provided at a coverage of 0.06 g/m2 on a dry basis on a surface of a PET film of DIAFOIL K880 manufactured by MITSUBISHI POLYESTER FILM CORPORATION as a substrate) corresponding to the sample was applied onto the identical mount at its position different from the position of the sample so that the surface of the dye layer faced upward. Each mount was folded back so that dye layer surface in the sample and the dye layer surface in the reference ribbon were put on top of and brought into contact with each other. In this state, heat sealing was carried out under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec, followed by separation. The assembly was then visually inspected for residual dye layer (undesired transfer of dye layer) in each of the sample and the reference ribbon 2. The results were evaluated according to the same criteria as the heat resistant adhesion 1. In this case, the heat resistant adhesion test was carried out by the following two testing methods. In one of the testing methods, the heat sealing was carried out in such a state that both the thermal transfer sheets of Example D and Comparative Example D as samples and the reference ribbon 2 were allowed to stand at room temperature. In the other testing method, the heat sealing was carried out after both the sample thermal transfer sheets and the reference ribbon 2 were allowed to stand under an environment of 40° C. and 90% RH for 16 hr.
(Adhesion to Image Receiving Sheet)
Each of the thermal transfer sheets of Example D and Comparative Example D and a specialty standard set of an image receiving sheet for a digital color printer P-200, manufactured by Olympus Optical Co., LTD. were put on top of each other so that the dye layer surface in the thermal transfer sheet was brought into contact with the image receiving surface in the image receiving sheet. The assembly was heat sealed under conditions of temperature 100 to 130° C., pressure 34.3×104 Pa, and pressing time 2 sec. Thereafter, both the sheets were separated from each other and were visually inspected for the state of separation between the dye layer in the sample and the image receiving layer in the image receiving sheet, and the results were evaluated according to the following criteria. In this case, the heat sealing of the thermal transfer sheet and the image receiving sheet was carried out in such a state that these sheets were allowed to stand at room temperature.
Evaluation Criteria
◯: No abnormal transfer of image receiving layer onto dye layer side took place.
x: Abnormal transfer of image receiving layer onto dye layer side took place.
The results of evaluation of each item are shown in Table 4 below.
Fifth Aspect of Invention
A 6 μm-thick polyethylene terephthalate (PET) film (DIAFOIL K 203 E, manufactured by Mitsubishi Polyester Film Co., Ltd.) subjected to easy-adhesion treatment was provided as a substrate. A liquid composition E having the following composition for an adhesive layer was gravure coated onto the easy-adhesion treated face in the PET film at a coverage of 0.2 g/m2 on a dry basis, and the coating was dried to form an adhesive layer. A liquid composition E(i) having the following composition for a dye layer was then gravure coated on the adhesive layer at a coverage of 0.8 g/m2 on a dry basis, and the coating was dried to form a dye layer. Thus, a thermal transfer sheet of Example E1 was prepared. In this case, a liquid composition E having the following composition for a heat-resistant slip layer was previously gravure coated on the other side of the substrate at a coverage of 1.0 g/m2 on a dry basis, and the coating was dried to form a heat resistant slip layer.
Thermal transfer sheets were prepared in the same manner as in Example E1, except that coating liquids prepared according to formulations shown in Table 5 were used as the coating liquid E for an adhesive layer.
Evaluation Test E
(Evaluation of Transferred Image Density)
The thermal transfer sheets prepared in Example E and Comparative Example E were used in combination with an image receiving sheet (KL36-IP, manufactured by Canon Inc.), and printing was carried out with Card Photo Printer CP-200 manufactured by Canon Inc. The maximum density (cyan) in the printed portion was measured with a Macbeth densitometer RD-918, manufactured by Sakata INX Corp. The thermal transfer sheet was patched to a cyan panel part in genuine media, and a cyan blotted image (gradation value 255/255: density max) print pattern was printed. The printing was carried out under an environment of temperature 30° C. and humidity 50%. In the evaluation, the maximum density was compared with that of the reference ribbon (a ribbon in which any adhesive layer is not interposed (Comparative Example E1)), and the results were rated as follows.
⊚: density of not less than 110%.
◯: density of not less than 105% and less than 110%
(Suitability for Printing)
Printing was carried out under the following conditions for evaluation of suitability for printing.
The thermal transfer sheet and the image receiving sheet as used in the evaluation of transferred image density were provided. The thermal transfer sheet was patched to yellow, magenta, and cyan panel parts in genuine media, and a black blotted image (gradation value 255/255: density max) print pattern was printed and was evaluated, and the results were rated according to the following criteria. After storage of the thermal transfer sheet and the image receiving sheet under an environment of temperature 40° C. and humidity 90% for two weeks, the printing was carried out under two environments, that is, under an environment of temperature 30° C. and humidity 500% and under an environment of temperature 40° C. and humidity 90%.
<Evaluation Criteria for Suitability for Printing>
◯: Defective printing phenomena such as abnormal transfer, uneven transfer, and omission of transfer did not occur for all the thermal transfer sheets patched respectively to the yellow, magenta, and cyan panel parts.
Δ ◯: Defective printing phenomena such as abnormal transfer, uneven transfer, and omission of transfer occurred for one of the three patched thermal transfer sheets (for the thermal transfer sheet patched to the cyan panel part).
Δ: Defective printing phenomena such as abnormal transfer, uneven transfer, and omission of transfer occurred for two of the three patched thermal transfer sheets (for the thermal transfer sheets patched respectively to the magenta panel part and the cyan panel part).
x: Defective printing phenomena such as abnormal transfer, uneven transfer, and omission of transfer occurred for all the three patched thermal transfer sheets.
The evaluation results for each item are shown in Table 5 below.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-011610 | Jan 2004 | JP | national |
| 2004-055681 | Mar 2004 | JP | national |
| 2004-055682 | Mar 2004 | JP | national |
| 2004-070969 | Mar 2004 | JP | national |
| 2004-089716 | Mar 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/00700 | 1/20/2005 | WO | 00 | 7/17/2006 |
