JP2009061679A - Thermal transfer sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer sheet which has improved slip properties, during non-heating, of a heat-resistant lubricating layer of the thermal transfer sheet and, therefore, can hardly cause a print deviation in length between the colors of yellow, magenta and cyan, even in case images indicating a different print ratio in the yellow, magenta and cyan assortment, are printed, and also, lees in the thermal head, when, for example, the thermal transfer sheet incorporating coloring material layers of yellow, magenta, cyan, etc. one after another on the plane, is used. <P>SOLUTION: This thermal transfer sheet 1 has at least, not less than two thermal transfer coloring material layers 3, formed one after another on the plane, on one side of a base sheet 2 and a heat-resistant lubricating layer 4 formed on the other side of the base sheet 2. In addition, the heat-resistant lubricating layer 4 contains a thermoplastic resin including a hydroxyl group, a polyisocyanate, a phosphate-based surfactant and a high-density polyethylene wax particle. It is possible to inhibit the print deviation in length between the colors of yellow, magenta, cyan, etc. by upgrading the slip properties of the heat-resistant lubricating layer during non-heating and lessening the difference in the slip properties of the heat-resistant lubricating layer on heating and non heating. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermal transfer sheet, and in particular, improves the slip property (slidability) when a heat-resistant slipping layer of a thermal transfer sheet is not heated, and has a color material layer of, for example, yellow, magenta, cyan, etc. The present invention relates to a thermal transfer sheet in which even when images having different printing ratios of yellow, magenta, and cyan are printed, the print length is not easily shifted between yellow, magenta, and cyan.

  Conventionally, as a heat-resistant slipping layer of a thermal transfer sheet, as described in Patent Documents 1, 2, 3, etc., as a cleaning component for polyvinyl acetal resins and polyisocyanates, phosphate ester surfactants, and thermal heads , Calcium carbonate, talc, aluminosilicate, clay, zeolite, Teflon (registered trademark) powder, zinc oxide, magnesium oxide, titanium oxide, silica, carbon, heat-resistant lubricant containing fine particles selected from the group consisting of condensates of benzoguanamine and formaldehyde Sexual layers are known.

  At the stage when this type of heat-resistant slipping layer was prepared, the phosphate ester surfactant, which is a slipping component, is present in the layer and on the surface of the heat-resistant slipping layer. A colorant layer of a phosphate ester-based surfactant that is a slipping component when the thermal transfer sheet having the heat-resistant slipping layer is stored in a wound state (small roll ribbon) for a long period of time. There was a problem that the slipping to the side and the heat-resistant slipping layer / coloring material layer into the layer occurred and the slipping property when not heated was lowered (frictional force was increased). However, even in such a state where the sinking into the layer occurs, when heat is applied to the heat resistant slipping layer from the thermal head, the phosphate ester surfactant is added from the heat resistant slipping layer to the heat resistant slipping layer. It exudes to the surface of the heat-sensitive layer and gives an excellent slip property between the thermal head and the thermal transfer sheet. In other words, this heat-resistant slipping layer has excellent slip properties (low frictional force) at the time of printing (heating) when stored in a wound state for a long time, but at the time of non-printing (non-heating) ) Has a problem that the slip property is inferior (the frictional force is high).

  This phenomenon is not a major problem when the color material layer of the thermal transfer sheet is a single color. However, when two or more color layers are provided in the surface direction in the flow direction of the thermal transfer sheet, each color is different. Due to the difference in the printing rate of the material layers, there may be a problem that the printing lengths of the respective color material layers are different (resulting in printing displacement). For example, when printing an image with a high yellow printing rate (an image with a lot of yellow or a strong yellowish color) on a thermal transfer sheet in which the three primary colors of yellow, magenta, and cyan are used in sequence, generally used. Considering an example, in a conventional heat-resistant slipping layer, the heat-resistant slipping layer is always in a heated state during yellow printing, so the heat-resistant slipping layer has a good slip property, and a thermal transfer sheet and a thermal transfer image receiving sheet are better. However, the heat-resistant slipping layer was not heated very much when printing magenta and cyan with low printing rate, and the slip resistance of the heat-resistant slipping layer was reduced. Since it is not so good at the time of non-heating, the conveyance of the thermal transfer sheet and the thermal transfer image-receiving sheet is also deteriorated, and the print tends to be shortened (the print is shrunk).

For this reason, in such an image print (with a high yellow print rate), the yellow print is long and the magenta and cyan prints are short, resulting in an image created by superimposing yellow, magenta, and cyan. In some cases, there was a deviation between yellow and magenta and cyan.
Japanese Patent No. 3517312 Japanese Patent No. 3243304 Japanese Patent No. 3410157

  Accordingly, the present invention has been made in view of such a situation, and improves the slip property (slidability) when the heat-resistant slipping layer of the thermal transfer sheet is not heated. For example, yellow, magenta, cyan, etc. Using a thermal transfer sheet with color material layers arranged in sequence, even if images with different printing rates of yellow, magenta, and cyan are printed, the print length is less likely to shift between yellow, magenta, and cyan. An object of the present invention is to provide a thermal transfer sheet that is less prone to residue.

  According to a first aspect of the present invention, there is provided a thermal transfer sheet in which at least two or more thermal transfer colorant layers are formed on one surface of a base sheet in the surface order, and the heat resistant slipping layer is formed on the other side of the base sheet. In the thermal transfer sheet in which the heat-resistant slipping layer is formed, the heat-resistant slipping layer contains a hydroxyl group-containing thermoplastic resin, a polyisocyanate, a phosphate-based surfactant, and high-density polyethylene wax particles, The polyethylene wax content is 0.5 to 8% by mass, and the high-density polyethylene wax is a spherical particle having a melting point of 110 ° C. or more and 140 ° C. or less and an average particle size of 7 to 12 μm. By improving the slipperiness of the heat-resistant slipping layer when not heated, and ensuring the slipperiness of the heat-resistant slipping layer when printing (heating), the hue between yellow, magenta, cyan, etc. The deviation of the printing length can be prevented of. In addition, by regulating the content range of the high-density polyethylene wax, it is possible to ensure proper lubricity and prevent the residue from adhering to the thermal head. And by defining the melting point of the high-density polyethylene wax, the high-density polyethylene wax does not melt and forms the heat-resistant slip layer without any abnormality in the drying process after coating the heat-resistant slip layer of the thermal transfer sheet. Can do. By defining the range of the average particle diameter of the high-density polyethylene wax, the high-density polyethylene wax protrudes from the surface of the heat-resistant slip layer formed on the thermal transfer sheet, so that appropriate slipperiness can be provided.

  As a second aspect, the hydroxyl group-containing thermoplastic resin according to the first aspect is a polyvinyl acetal resin. Thus, by reacting and curing the polyvinyl acetal resin with polyisocyanate, the film strength of the heat resistant slipping layer can be increased, and the heat resistance can be increased. As a third aspect, the heat-resistant slipping layer according to the first or second aspect includes inorganic or organic fine particles. Thereby, even if there is a change in the heating temperature at the time of printing, it is possible to give an appropriate slipperiness.

  As a fourth aspect, the thermal transferable color material layer according to any one of the first to third aspects includes at least a yellow color material layer, a magenta color material layer, and a cyan color material layer. Thereby, it is possible to prevent the print length from being shifted between the hues in the full-color thermal transfer image. As a fifth aspect of the present invention, the thermal transfer sheet according to any one of the first to fourth aspects is for card creation. The thermal transfer image receiving sheet, which is the transfer target, is in the form of a card. Even if printing is performed by thermal transfer in combination with the above thermal transfer sheet, the thermal transfer image receiving sheet is not flexible and has high rigidity. In this case, it is possible to prevent the print length from being shifted between hues such as yellow, magenta, and cyan.

  The thermal transfer sheet of the present invention can improve the slip property (slidability) when the heat resistant slipping layer is not heated. For example, a thermal transfer sheet provided with color material layers of yellow, magenta, cyan, etc. in a surface sequence is used. Even when images with different printing ratios of yellow, magenta, and cyan were printed, it was possible to prevent the print length from being shifted between yellow, magenta, and cyan, that is, between different hues. As a result, it was possible to obtain a print having a very clear and excellent thermal transfer image.

  The thermal transfer recording material according to the present invention comprises a combination of the above thermal transfer sheet and a card-type thermal transfer image receiving sheet, and transfers the color material in the thermal transfer color material layer of the thermal transfer sheet to the thermal transfer image receiving sheet by heating means. It is something to accept. With this thermal transfer recording material, it was possible to obtain a clear and excellent image-formed product with no deviation in print length between hues of yellow, magenta, cyan, etc. in a card-like print.

  FIG. 1 is a schematic cross-sectional view showing one embodiment of a thermal transfer sheet 1 of the present invention. A yellow color material layer (Y), a magenta color material layer (M), and cyan are formed on one surface of a base sheet 2. The three heat transferable color material layers 3 of the color material layer (C) are repeatedly formed in the surface order, and the heat resistant slipping layer 4 is formed on the other surface of the base sheet 2. For example, a primer layer (adhesive layer) is provided between the base sheet and the heat-resistant slip layer, or a primer layer (adhesive layer) is provided between the base sheet and the heat transferable color material layer (not shown in FIG. 1). In addition to the three types of Y, M, and C, a Bk (black) color material layer can also be used as a heat transferable color material layer. It is also possible to adopt a protective layer-integrated thermal transfer sheet in which Y, M, C, BK, and a protective layer are repeatedly formed in the surface order on the side where the heat transferable color material layer is provided. In any case, in the thermal transfer sheet of the present invention, the heat-resistant slipping layer includes a hydroxyl group-containing thermoplastic resin, polyisocyanate, a phosphate ester surfactant, and high-density polyethylene wax particles.

Hereinafter, each layer constituting the thermal transfer sheet of the present invention will be described in detail.
(Substrate sheet)
As the base material sheet 2 of the thermal transfer sheet used in the present invention, any material may be used as long as it has a conventionally known degree of heat resistance and strength, for example, about 0.5 to 50 μm, preferably about 1 to 10 μm. Polyethylene terephthalate film of thickness, 1,4-polycyclohexylenedimethylene terephthalate film, polyethylene naphthalate film, polyphenylene sulfide film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, Examples thereof include cellulose derivatives such as cellulose acetate, polyethylene films, polyvinyl chloride films, nylon films, polyimide films, ionomer films, and the like.

  In the base material sheet, an adhesive treatment is performed on the surface on which the heat transferable color material layer (dye layer) is formed, on the surface on which the heat resistant slipping layer is formed, and on both surfaces of the base material sheet. . When the plastic film of the base material sheet is formed by applying an adhesive layer thereon, the wettability, adhesiveness, etc. of the coating solution are likely to be insufficient, and thus an adhesive treatment can be performed. As the adhesion treatment, known resin surface modification such as corona discharge treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, surface roughening treatment, chemical treatment, plasma treatment, low temperature plasma treatment, primer treatment, grafting treatment, etc. Quality technology can be applied as it is. Two or more of these treatments can be used in combination. The primer treatment can be performed, for example, by applying a primer solution to an unstretched film at the time of film formation by melt extrusion of a plastic film and then stretching the film.

  Furthermore, as an adhesive treatment of the above base sheet, a primer layer (adhesive layer) is applied between the base sheet and the thermal transfer layer and / or between the base sheet and the heat-resistant slip layer. It is also possible to form. The primer layer can be formed from a resin as shown below. Polyester resin, Polyacrylate resin, Polyvinyl acetate resin, Polyurethane resin, Styrene acrylate resin, Polyacrylamide resin, Polyamide resin, Polyether resin, Polystyrene resin, Polyethylene resin, Polypropylene Examples thereof include vinyl resins such as resins, polyvinyl chloride resins, polyvinyl alcohol resins, and polyvinylidene chloride resins, polyvinyl acetal resins such as polyvinyl acetoacetal and polyvinyl butyral, and cellulose resins.

(Heat resistant slipping layer)
The heat-resistant slip layer of the thermal transfer sheet of the present invention contains a hydroxyl group-containing thermoplastic resin, polyisocyanate, phosphate ester surfactant, and high density polyethylene wax particles. Specific examples of the hydroxyl group-containing thermoplastic resin include polyester resins, polyacrylate resins, polyvinyl acetate resins, styrene acrylate resins, polyurethane resins, polyolefin resins, polystyrene resins, and polyresins. Examples include vinyl chloride resins, polyether resins, polyamide resins, polycarbonate resins, polyethylene resins, polypropylene resins, polyacrylate resins, polyacrylamide resins, polyvinyl chloride resins, polyvinyl butyral resins, and polyvinyl acetoacetal resins. Among these, particularly preferred resins are polyvinyl acetal resins such as polyvinyl butyral resins and polyacetoacetal resins having many hydroxyl groups in the molecule.

  In addition, the polyisocyanate used in the heat resistant slipping layer crosslinks the hydroxyl group-containing thermoplastic resin using the hydroxyl group, thereby improving the coating strength or heat resistance of the heat resistant slipping layer. As the polyisocyanate, various kinds of polyisocyanate have been conventionally known. Of these, it is desirable to use an adduct of an aromatic isocyanate. As the aromatic polyisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, or a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, Examples include p-phenylene diisocyanate, trans-cyclohexane, 1,4-diisocyanate, xylylene diisocyanate, triphenylmethane triisocyanate, and tris (isocyanatophenyl) thiophosphate, especially 2,4-toluene diisocyanate and 2,6-toluene diisocyanate. Or, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate is preferable.

  The amount of polyisocyanate used is suitably in the range of 5 to 200 parts by mass with respect to 100 parts by mass of the above-mentioned hydroxyl group-containing thermoplastic resin constituting the heat-resistant active layer. The molar ratio of —NCO / —OH is preferably in the range of 0.8 to 2.0. If the amount of polyisocyanate used is too small, the crosslinking density is low and the heat resistance becomes insufficient, which is not preferable. On the other hand, if the amount of polyisocyanate used is too large, it becomes difficult to control the shrinkage of the coating film formed, the time for curing becomes long, unreacted isocyanate groups remain in the heat resistant slipping layer, and air This causes problems such as reacting with the water content.

The phosphate ester-based surfactant contained in the heat resistant slipping layer improves the slipperiness of the heat resistant slipping layer, and can have sufficient slipperiness particularly when heated by a thermal head (during printing). As phosphate ester surfactants,
1) A long-chain alkyl phosphate ester, for example, a saturated or unsaturated higher alcohol having 6 to 20 carbon atoms, preferably 12 to 18 carbon atoms, such as cetyl alcohol, stearyl alcohol, oleyl alcohol, etc. and phosphoric acid Mono and / or diester, etc.
2) Phosphate esters such as polyoxyalkylene alkyl ether or polyoxyalkylene alkyl aryl ether,
3) Alkylphenol or alkylnaphthol (nonylphenol) having at least one, preferably 1-2 alkyl groups having an alkylene oxide adduct (usually 1 to 8 addition moles) or 8 to 12 carbon atoms of the saturated or unsaturated alcohol. Nonionic or anionic phosphate ester surfactants such as phosphate mono- or diester salts of dodecylphenol and diphenylphenol).

  The usage-amount of said phosphate ester type surfactant is 1-100 mass parts per 100 mass parts of said hydroxyl-containing thermoplastic resins, Preferably it is 2-50 mass parts. If the amount of phosphate ester surfactant added is small, the thermal releasability to the thermal head will not be sufficient, causing print defects, head defects, and sticking. When the thermal transfer sheet is wound and stored, the dye of the thermal transfer colorant layer facing the heat transfer layer is transferred to the heat resistant slipping layer, or the phosphate ester surfactant of the heat resistant slipping layer is used. It may shift to the heat transferable color material layer excessively and affect the color reproducibility of the printed matter.

  The high-density polyethylene wax particles contained in the heat-resistant slip layer have a high function of improving the slipperiness of the heat-resistant slip layer when not heated. The high density polyethylene wax particles are polyethylene wax particles having a density of 0.94 to 0.97, and are obtained by finely pulverizing polyethylene wax into a granular form. There is a low density polyethylene wax that is not a polyethylene wax used in the present invention, and when comparing the molecular structure, the low density polyethylene is conspicuously branched due to the structure of the ethylene polymer. Is relatively composed mainly of a linear structure of polyethylene.

  The high-density polyethylene wax particles used in the heat-resistant slip layer of the thermal transfer sheet of the present invention preferably have an average particle size of 15 μm or less and an average particle size of 7 to 12 μm. If the particle size is too small, the function of imparting the slipperiness of the heat resistant slipping layer will be reduced. On the other hand, if the particle size is too large, debris will easily adhere to the thermal head. The shape of the high-density polyethylene wax particles can be spherical, square, columnar, needle-like, plate-like, indeterminate, etc., but in terms of imparting the slipperiness of the heat-resistant slipping layer of the present invention, It is preferable to take the form of spherical particles, providing excellent slipperiness and making it difficult for debris to adhere to the thermal head. By setting the range of the average particle diameter of the high-density polyethylene wax to the above-mentioned regulation, the high-density polyethylene wax protrudes on the surface of the heat-resistant slip layer formed on the thermal transfer sheet and can have appropriate lubricity. .

  The high-density polyethylene wax particles are preferably contained at a ratio of 0.5 to 8% by mass with respect to the total solid content (100% by mass) of the heat-resistant slip layer. If the content is too small, the slipping property of the heat resistant slipping layer is lowered, and if the content is too large, debris tends to adhere to the thermal head. The melting point of the high density polyethylene wax particles is preferably 110 ° C. or higher and 140 ° C. or lower. If the melting point is too low, the storage stability of the thermal transfer sheet is reduced, or the high-density polyethylene wax particles themselves melt in the drying process after the application of the heat-resistant slip layer. On the other hand, if the melting point is too high, the transfer of the color material at the time of thermal transfer tends to be non-uniform due to surface irregularities of the heat-resistant slip layer. The melting point was measured with a differential scanning calorimeter (DSC).

  The heat-resistant slipping layer contains a phosphate ester surfactant and high-density polyethylene wax particles in order to provide slipping properties during printing and non-printing. Therefore, inorganic or organic fine particles can be added. Examples of the inorganic fine particles include clay minerals such as talc and kaolin, carbonates such as calcium carbonate and magnesium carbonate, hydroxides such as aluminum hydroxide and magnesium hydroxide, sulfates such as calcium sulfate, and oxides such as silica. Inorganic fine particles such as graphite, nitrate and boron nitride. Organic fine particles include acrylic resin, Teflon (registered trademark) resin, silicone resin, lauroyl resin, phenol resin, acetal resin, polystyrene resin, nylon resin, etc., or crosslinked resin obtained by reacting these with a crosslinking agent. Examples thereof include fine particles.

  Any of the above inorganic or organic fine particles preferably has an average particle size of about 0.5 to 3 μm. The inorganic or organic fine particles are desirably used at a ratio of 5 to 40 parts by mass with respect to 100 parts by mass of the hydroxyl group-containing thermoplastic resin. If the addition amount is too small, the slipperiness is insufficient. If the amount is too large, the flexibility and film strength of the heat-resistant slip layer formed are lowered. In order to provide a heat resistant slipping layer on a base sheet, the above components are dissolved in an appropriate solvent such as acetone, methyl ethyl ketone, toluene, xylene, etc., and used as a heat resistant slipping layer forming ink. It forms on a base material sheet by the usual suitable printing methods, such as a coater and a wire bar, and the apply | coating method. Next, drying is performed by heating to a temperature of 30 ° C. to 80 ° C., and a resin having a hydroxyl group which is an active hydrogen group is reacted with polyisocyanate to form a heat-resistant slipping layer.

  The thickness of the heat resistant slipping layer is 0.5 to 5 μm, preferably 1 to 2 μm. If this film thickness is less than 0.5 μm, the effect as a heat-resistant slip layer is not sufficient, and if it is thicker than 5 μm, heat transfer from the thermal head to the heat transferable color material layer becomes worse, and the print density This causes the disadvantage of lowering. When a heat resistant slipping layer is provided on the base sheet, it is preferable to heat in order to promote the reaction between the binder resin and the polyisocyanate, but in order not to affect the heat transferable color material layer. In addition, it is preferable to provide a heat transferable color material layer after the heat resistant slipping layer is provided on the base sheet.

(Heat transferable color material layer)
In the present invention, the heat transferable color material layer 3 may be either a color material layer made of heat-meltable ink or a color material layer containing a sublimable dye. The hot-melt ink used in the present invention comprises a colorant and a vehicle, and various additives are added as necessary. As the colorant, among organic or inorganic pigments or dyes, those having a color density required as a recording material and not discolored by light, heat, temperature or the like are preferable. In addition, a substance that develops color when heated or a substance that develops color when in contact with a substance applied to the transfer target can also be used. In addition to cyan, magenta, yellow, black and the like, various colorants can be used as the colorant.

  The vehicle is mainly composed of a wax, and in addition, a mixture of a wax and a drying oil, resin, mineral oil, cellulose, rubber derivatives, or the like is used. The heat transferable color material layer made of heat meltable ink may contain a heat conductive material in order to give good heat conductivity and melt transferability. Examples of such a heat conductive material include carbonaceous materials such as carbon black, aluminum, copper, tin oxide, and molybdenum disulfide. Examples of the method for forming the heat transferable color material layer on the base film using the above hot melt ink include known methods such as hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, and roll coating. It is done. The thickness of the heat transferable color material layer made of a heat-meltable ink can be appropriately determined in consideration of the required printing density, thermal sensitivity, etc., and is usually about 0.1 to 30 μm.

  The heat transferable color material layer (dye layer) containing a sublimable dye is obtained by dispersing or dissolving a heat transferable dye in a binder resin. As the binder resin, those having a moderate affinity with the dye, and those in which the dye in the binder resin sublimates (thermally diffuses) by heating with a thermal head and is transferred to the transfer target are suitable. Use resin that does not transfer. Examples of the resin used as such a binder resin include cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose nitrate, cellulose acetate, and acetic acid / butyric acid cellulose, polyvinyl alcohol, and polyacetic acid. Examples thereof include vinyl resins such as vinyl, polyvinyl acetoacetal, polyvinyl butyral, polyacrylamide, and polyvinyl pyrrolidone, polyester, and polyamide.

  The proportion of the dye contained in the heat transferable color material layer varies depending on the dye sublimation (melting) temperature, dyeing property, etc., but is preferably 30 parts by mass or more, more preferably 100 parts by mass of the binder resin. Is 30 to 300 parts by weight. When the amount of the dye is less than 30 parts by mass, the printing density and the thermal sensitivity are low, and when it exceeds 300 parts by mass, the storage property and the adhesion of the heat transferable color material layer to the base film are deteriorated.

  The dye used in the heat transferable color material layer is a dye which melts, diffuses or sublimates by heat and moves to the transfer target, and a disperse dye is particularly preferably used. The dye is selected in consideration of sublimation (melting) property, hue, light resistance, solubility in a binder resin, and the like. As these dyes, for example, methine series such as diarylmethane series, triarylmethane series, thiazole series, merocyanine, indoaniline, acetophenone azomethine, pyrazoloazomethine, imidazole azomethine, imidazoazomethine, azomethine series represented by pyridone azomethine , Xanthene series, oxazine series, dicyanostyrene, cyanomethylene series represented by tricyanostyrene, thiazine series, azine series, acridine series, benzeneazo series, pyridoneazo, thiophenazo, isothiazole azo, pyrrole azo, pyrazole azo, imidazole azo, Azos such as thiadiazole azo, triazole azo, disazo, spiropyran, indolinospiropyran, fluoran, rhodamine lactam, naphthoquinone, anthraquino Systems include the quinophthalone like.

  In order to provide the heat transferable color material layer, which is a dye layer, on the base film, a known method can be used. For example, a dye and binder resin are dissolved or dispersed together with a solvent to prepare an ink composition for a heat transferable color material layer, which is provided on a base film by a method appropriately selected from known printing methods or coating methods. It ’s fine. The thickness of the dye layer is 0.2 to 5.0 μm, preferably about 0.4 to 2.0 μm.

  The heat-transferable color material layer described above is required to form at least two heat-transferable color material layers having different hues in the surface order on the base sheet, but two or more heat-transferable color material layers The conditions of the above are two or more dye layers using a sublimable dye, a combination of a dye layer and a heat transferable color material layer of heat-meltable ink, or two heat-transferable color material layers of heat-meltable ink. There may be more than one. In the present invention, in particular, a yellow color material layer, a magenta color material layer, and a cyan color material layer are formed in the surface order as a heat transferable color material layer containing a sublimation dye in the base sheet, and a high color comparable to a full color photographic image. It is preferable to form a clear image in which a quality thermal transfer image is formed and a shift in print length is prevented between hues in a full color thermal transfer image. In the case of a black character or pattern thermal transfer image, it is possible to obtain black by overlaying the above three colors of the yellow color material layer, magenta color material layer, and cyan color material layer of the dye layer. It is preferable that a color material layer made of black heat-meltable ink using a black colorant is added to the base sheet. As a result, a clear image having a high black density can be obtained.

(Transfer)
The thermal transfer sheet of the present invention is preferably used in combination with a card using a plastic sheet as a substrate to be transferred. This is because, in the case of a material to be transferred, which is not flexible as represented by a card and has a high rigidity, it is difficult to convey the material to be transferred with a thermal transfer printer with accurate dimensional accuracy, such as yellow, magenta, This is because, when images having different printing ratios such as cyan are printed, deviations in the printing length are likely to occur between the hues, and if the thermal transfer sheet of the present invention is applied, deviations in the printing length can be eliminated. Needless to say, a sheet using a conventionally known paper, synthetic paper or the like as a thermal transfer image receiving sheet can also be used.

  A card as a transfer target is a plastic sheet, paper or the like used as a base material, but when a sublimable dye is used for the heat transferable color material layer of a thermal transfer sheet used in combination, the card base material is A material having dye receptivity is used on the recording surface, or in the case of a substrate not having dye receptivity, a material having a dye receptive layer formed on the surface is used. The dye receiving layer is for maintaining a formed image by receiving a sublimable dye, and is formed from various resins.

  Examples of the resin for forming the dye receiving layer include polyolefin resins such as polypropylene, halogenated polymers such as polyvinyl chloride and polyvinylidene chloride, polyvinyl acetate, ethylene vinyl acetate copolymer, and vinyl chloride vinyl acetate. Copolymers, vinyl resins such as polyacrylic esters, acetal resins such as polyvinyl formal, polyvinyl butyral, polyvinyl acetal, various saturated and unsaturated polyester resins, polycarbonate resins, cellulose resins such as cellulose acetate, polystyrene, acrylic resins Examples thereof include styrene resins such as rho styrene copolymer and acrylonitrile-styrene copolymer, polyamide resins such as urea resin, melamine resin and benzoguanamine resin. These resins can be arbitrarily blended and used within a compatible range.

  In addition, the receiving layer resin as described above may cause fusion with the binder resin of the dye layer that retains the dye during thermal transfer of image formation. Therefore, in order to obtain good releasability, phosphate ester, surfactant It is preferable to internally add various releasing agents such as an agent, a fluorine compound, a fluorine resin, a silicone compound, a silicone oil, and a silicone resin into the receiving layer, and in particular, a modified silicone oil is preferably added and cured. .

  When the card substrate is a material having dye receptivity on the recording surface, a polyvinyl chloride resin sheet is often used as the substrate, but other plastic sheets can also be used. For example, polypropylene resin, non-crystalline cyclic olefin copolymer, ABS, polyester resin (= polyethylene terephthalate resin), non-crystalline polyester resin, polycarbonate resin, polyarylate resin, polyamide resin or polyimide resin alone or these resins It is preferable to use a sheet made of a blend resin of these resins and other resins. Of course, polyolefin resins, polystyrene resins, and polyvinyl chloride resins other than those described above can also be used. The plastic sheet may be transparent, but it may be whitened by blending a highly concealing filler such as titanium dioxide and used as a white sheet.

  The thermal transfer sheet of the present invention is suitable for the production of a card made of polyvinyl chloride resin, and the gradation of the card base material comprising the dye layer of the heat transferable color material layer without forming a special dye receiving layer. Characters, symbols, barcodes, etc. made up of adhesive images and meltable ink layers can be printed directly. In the present invention, a particularly preferable card substrate contains 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass of a plasticizer per 100 parts by mass of polyvinyl chloride, and the card substrate is sublimated. In addition to having sufficient dyeing properties with respect to reactive dyes, it also has good adhesion to hot melt inks. The card substrate may have a single layer configuration, or may have a multilayer configuration in which a transparent resin layer is provided on at least one surface of a center core containing a white pigment.

(Incorrect print length)
The problem to be solved by the thermal transfer sheet of the present invention is that when printing images with different hues and different printing ratios, the print length shifts between the hues, the thermal transfer sheet, the thermal head, the transfer object, etc. This will be described below with reference to FIG. In the case where the printing rate is high, for example, when the area of the maximum size of the image to be transferred 7 on which the image can be formed is 100%, the image is formed at a ratio (area) of about 60 to 90% of the size. As shown in the half, the thermal transfer sheet 1 is sandwiched between the thermal head 5 and the platen roll 6 when printing the thermal transfer sheet 1 due to friction with the heat-resistant slipping layer of the thermal transfer sheet 1 of the thermal head 5. Then, the image is formed while being pressurized and heated to convey the thermal transfer sheet 1 and the transfer medium 7 in the direction of the arrow shown in the figure. At that time, the frictional force of the thermal transfer sheet 1 with the thermal head is lowered, and the print length is in the state shown in FIG. In this case, the rate of heating by the thermal head is relatively high, the rate of the non-heated state is low, and the slidability of the heat-resistant slipping layer of the thermal transfer sheet 1 with the thermal head 5 is relatively good.

  On the other hand, when the printing rate is low, for example, when the area of the maximum size on which the image of the transfer body 7 can be formed is 100%, the image is formed at a rate (area) of about 5 to 30% of the size. As shown in the lower half of FIG. 2, when the thermal transfer sheet 1 is printed in the friction with the heat-resistant slipping layer of the thermal transfer sheet 1 of the thermal head 5, the thermal transfer sheet 1 is formed between the thermal head 5 and the platen roll 6. It is sandwiched between and pressed and heated, and an image is formed while the thermal transfer sheet 1 and the transfer target 7 are conveyed in the direction of the arrow shown in the figure. At that time, the frictional force between the thermal transfer sheet 1 and the thermal head is increased, and the printing length is in the state shown in FIG. In this case, the rate of heating by the thermal head is relatively low, that is, the rate of the non-heated state is high, and the sliding property of the heat-resistant slipping layer of the thermal transfer sheet 1 with the thermal head 5 is poor. As a result, the print length is Compared with the case where the printing rate is high, it is shorter. (L> M)

  Further, with reference to FIG. 3, when printing images with different hues and different printing ratios, an example of using a card as an object to be transferred is shown as an example in which the printing length shifts between hues. FIG. 3 shows the printing start and printing end in units of cards. As the printing pattern, a pattern having a horizontal stripe shape area 2 having a width of 1 mm on the printing end side of the card and the other area 1 is used. The area 2 is printed with one heat transferable color material layer in hues of yellow (Y), magenta (M), and cyan (C), for example, and the area 1 is the heat transferable color material used for printing in the area 2 A layer is printed with a heat transferable color material layer having a different hue. For example, when area 2 is printed with magenta (M), yellow (Y) and cyan (C) are used for area 1.

  When the above print pattern is printed using a conventional thermal transfer sheet, as shown in the lower half of FIG. 3, the magenta (M) print is shifted from the normal position in the area 2 on the print end side. Move to. In printing of each of the Y, M, and C heat transferable color material layers, the card and the heat transfer sheet are overlapped and pressed on the print start side at the start of printing. In this example, the Y and C color material layers are actually imaged by heating the thermal head from the printing start side. On the other hand, the color material layer of M is pressed by overlapping the card and the thermal transfer sheet on the printing start side, but the thermal head is not yet heated and is in an unheated state. As shown in FIG. 2, the thermal head is heated and the M image is formed only when it is sandwiched between the thermal head and the platen roll and transported in an unheated state and reaches the position of the region 2 on the printing end side. The The conventional thermal transfer sheet has a high frictional force with the thermal head when not heated, that is, the sliding property with the thermal head is poor, and accordingly, the card is also poorly transported. As a result, the print length is shortened, and as a result, as shown in the lower part of FIG. 3, the M thermal transfer image (region 2) is shifted to the print start side, that is, the upper side. This occurs because the Y and C thermal transfer images have a high printing rate and the M thermal transfer image has a low printing rate.

Next, the present invention will be described more specifically with reference to examples. Hereinafter, unless otherwise specified, parts or% is based on mass.
(Example 1)
Using a gravure coater on one surface of a base sheet of a polyethylene terephthalate film having a thickness of 6 μm that has been subjected to easy adhesion treatment, a ratio of 0.8 g / m ^{2 in} terms of solid content of the following heat-resistant slipping layer coating solution And dried to form a heat resistant slipping layer.
<Coating liquid 1 for heat resistant slipping layer>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Spherical high-density polyethylene wax (solid content ratio: 0.5 mass%) ^{* 1} 0.09 part (melting point: 110 to 118 ° C., (Average particle size 10μm)
-Methyl ethyl ketone 100.0 part-Toluene 100.0 part * 1; The numerical value of solid content ratio in polyethylene wax is the mass% with respect to the total solid (100 mass%) of a heat-resistant slipping layer. The numerical value of the solid content ratio in the polyethylene wax having the following composition has the same meaning.

A yellow dye layer (Y), a magenta dye layer (M), a cyan dye layer (C), and a heat-meltable black ink layer on the other surface of the base sheet (on the easy-adhesion treated surface) by a gravure printing machine, Four types of thermal transfer layers of the transferable protective layer were repeatedly formed in this order in the surface order. However, in this case, the four heat transferable color material layers are a yellow dye layer (Y), a magenta dye layer (M), a cyan dye layer (C), and a heat-meltable black ink layer. Each said dye layer (Y, M, C) is 1.0 g / m < ² > in conversion of solid content each using the following coating liquid for each dye layer (Y, M, C) using a gravure printing machine. It was prepared by coating and drying at a ratio. The heat-meltable black ink layer was coated with the following release layer coating liquid at a rate of 1 g / m ^{2 in} terms of solid content using a gravure printing machine and dried to form a release layer. The following heat-meltable black ink layer coating solution was applied and dried at a rate of 0.7 g / m ^{2 in} terms of solid content on the release layer using a gravure printing machine. The transferable protective layer is coated with the same release layer coating liquid used under the hot melt black ink layer at a rate of 1 g / m ^{2 in} terms of solid content using a gravure printing machine, and dried. After forming the release layer, the following protective layer coating solution is applied on the release layer at a rate of 0.8 g / m ^{2 in} terms of solid content and dried using a gravure printing machine. did. In addition, each dye layer, heat-meltable black ink layer, and transferable protective layer are 10 cm long along the flow direction of the base film, with no gaps, and the coating width in the width direction is The thermal transfer sheet of Example 1 was produced by continuously forming the base film in the full width and continuously.

<Yellow dye layer coating liquid (Y)>
Disperse dye (holon brilliant yellow-S-6GL) 5.5 parts Binder resin 4.5 parts (polyvinyl acetoacetal resin KS-5, manufactured by Sekisui Chemical Co., Ltd.)
・ Phosphate surfactant 0.1 part (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Polyethylene wax 0.1 part ・ Methyl ethyl ketone 45.0 parts ・ Toluene 45.0 parts

<Magenta dye layer coating solution (M)>
-Disperse dye (MS Red G) 1.5 parts-Disperse dye (Macrolex Red Violet R) 2.0 parts-Binder resin 4.5 parts (Polyvinylacetoacetal resin KS-5, manufactured by Sekisui Chemical Co., Ltd.)
・ Phosphate surfactant 0.1 part (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Polyethylene wax 0.1 part ・ Methyl ethyl ketone 45.0 parts ・ Toluene 45.0 parts

<Cyan dye layer coating solution (C)>
-Disperse dye (Kayaset Blue 714) 4.5 parts-Binder resin (polyvinylacetoacetal resin KS-5, manufactured by Sekisui Chemical Co., Ltd.) 4.5 parts-Phosphate ester surfactant 0.1 parts ( Price Surf A208N (Daiichi Pharmaceutical Co., Ltd.)
・ Polyethylene wax 0.1 part ・ Methyl ethyl ketone 45.0 parts ・ Toluene 45.0 parts

<Release layer coating solution>
・ Urethane resin (Chrisbon 9004, manufactured by DIC) 20.0 parts ・ Polyvinylacetoacetal resin (KS-5, manufactured by Sekisui Chemical Co., Ltd.) 5.0 parts ・ Dimethylform alumide 80.0 parts ・ Methyl ethyl ketone 120.0 parts

<Coating liquid for heat-meltable black ink layer>
・ 20.0 parts of vinyl chloride-vinyl acetate copolymer resin solution (Solvine CNL manufactured by Nissin Chemical Industry Co., Ltd.)
Carbon black 10.0 parts Methyl ethyl ketone / toluene (mass ratio 1/1) 70.0 parts

<Coating liquid for protective layer>
・ 100.0 parts of vinyl chloride-vinyl acetate copolymer resin (Solvine CNL Nissin Chemical Industry Co., Ltd.)
・ Toluene 150.0 parts ・ Methyl ethyl ketone 150.0 parts

(Example 2)
A thermal transfer sheet of Example 2 was produced in the same manner as in Example 1 except that the heat-resistant slipping layer coating liquid in Example 1 was changed to the following heat-resistant slipping layer coating liquid 2.
<Coating fluid 2 for heat resistant slipping layer>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Spherical high-density polyethylene wax (solid content ratio 3% by mass) 0.55 part (melting point 110 to 118 ° C., average particle size 10 μm) )
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Example 3)
A thermal transfer sheet of Example 3 was prepared in the same manner as in Example 1 except that the heat resistant slipping layer coating liquid in Example 1 was changed to the following heat resistant slipping layer coating liquid 3.
<Coating fluid 3 for heat resistant slipping layer>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Spherical high-density polyethylene wax (solid content ratio: 8% by mass) 1.54 parts (melting point: 110 to 118 ° C., average particle size: 10 μm) )
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

Example 4
A thermal transfer sheet of Example 4 was produced in the same manner as in Example 1 except that the coating solution for heat resistant slipping layer in Example 1 was changed to the coating solution 4 for heat resistant slipping layer described below.
<Coating fluid 4 for heat resistant slipping layer>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Spherical high-density polyethylene wax (solid content ratio 3 mass%) 0.55 part (melting point 110 to 118 ° C., average particle size 8 .5μm)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Example 5)
A thermal transfer sheet of Example 5 was produced in the same manner as in Example 1 except that the heat-resistant slipping layer coating solution in Example 1 was changed to the following heat-resistant slipping layer coating solution 5.
<Coating fluid 5 for heat resistant slipping layer>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Spherical high-density polyethylene wax (solid content ratio 3 mass%) 0.55 part (melting point 110 to 118 ° C., average particle size 7 .5μm)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Example 6)
A thermal transfer sheet of Example 6 was prepared in the same manner as in Example 1 except that the heat resistant slipping layer coating liquid in Example 1 was changed to the following heat resistant slipping layer coating liquid 6.
<Coating fluid 6 for heat resistant slipping layer>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 1.1 parts ・ Spherical high-density polyethylene wax (solid content ratio: 3 mass%) 0.55 parts (melting point: 110 to 118 ° C., average particle size: 12 μm) )
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Comparative Example 1)
A thermal transfer sheet of Comparative Example 1 was produced in the same manner as in Example 1 except that the heat resistant slipping layer coating liquid in Example 1 was changed to the following heat resistant slipping layer coating liquid 7.
<Coating fluid 7 for heat resistant slipping layer>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Comparative Example 2)
A thermal transfer sheet of Comparative Reference Example 2 was prepared in the same manner as in Example 1 except that the heat resistant slipping layer coating liquid in Example 1 was changed to the following heat resistant slipping layer coating liquid 8.
<Coating fluid 8 for heat resistant slipping layer>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Spherical high-density polyethylene wax (solid content ratio: 0.3 mass%) 0.05 part (melting point: 110 to 118 ° C., average particle size) (Diameter 10μm)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Comparative Example 3)
A thermal transfer sheet of Comparative Reference Example 3 was produced in the same manner as in Example 1 except that the heat resistant slipping layer coating liquid in Example 1 was changed to the following heat resistant slipping layer coating liquid 9.
<Coating fluid 9 for heat resistant slipping layer>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Spherical high-density polyethylene wax (solid content ratio: 10% by mass) 1.97 parts (melting point: 110 to 118 ° C., average particle size: 12 μm )
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Comparative Example 4)
A thermal transfer sheet of Comparative Reference Example 4 was prepared in the same manner as in Example 1 except that the heat resistant slipping layer coating liquid in Example 1 was changed to the following heat resistant slipping layer coating liquid 10.
<Coating fluid 10 for heat resistant slipping layer>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Spherical high-density polyethylene wax (solid content ratio 3 mass%) 0.55 part (melting point 110 to 118 ° C., average particle size 30 μm) )
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Comparative Example 5)
A thermal transfer sheet of Comparative Reference Example 5 was produced in the same manner as in Example 1 except that the heat resistant slipping layer coating liquid in Example 1 was changed to the following heat resistant slipping layer coating liquid 11.
<Coating fluid 10 for heat resistant slipping layer>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Amorphous high-density polyethylene wax (solid content ratio 3 mass%) 0.55 part (melting point 104-110 ° C., average particle size 8μm)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

  After producing the thermal transfer sheet of each of the above examples, the sample was stored at room temperature (25 ° C.) for 1 month in a wound state, and then subjected to the following evaluations and tests. The thermal transfer sheet immediately after being prepared by coating the heat-resistant slip layer has sufficient slipperiness with the thermal head even during non-heating in printing, and after coating the heat-resistant slip layer, This is because when three weeks or more have elapsed, the frictional force with the thermal head during non-heating increases, and the problem of misalignment of the print length, which is a problem, appears.

Using the thermal transfer sheet of each example produced as described above, evaluation of the amount of deviation of printing and evaluation of thermal head residue were performed by the following methods.
(Print displacement)
First, the thermal transfer sheet produced in each example was printed under the following printing conditions using the transfer target shown below.
<Printing conditions>
Transfer object: White vinyl chloride Card printer: Card printer
Printing pressure: 1.1kg / inch
Printing speed: 3msec / line
Print pattern: The pattern shown in FIG. 3, and the image was formed by transferring with the Y and C dye layers in the region 1 and transferring with the M dye layer in the region 2.
The printing energy was 0.18 mJ / dot for each of the Y and C dye layers in region 1 and 0.18 mJ / dot for the M dye layer in region 2.

(Evaluation)
Evaluation was performed by measuring the amount of misalignment of the prints in the regions 1 and 2 shown in FIG. The determination (corresponding to LM shown in FIG. 2) is X when the deviation is greater than 0.7 mm, Δ when 0.7 mm or less and 0.5 mm or more, and ○ when less than 0.5 mm. did.

(Thermal head residue)
In the printing conditions at the time of evaluating the deviation of the above printing, except that in each example, 100 cards were printed continuously, and then the thermal head was removed from the printer, and the thermal head residue was removed with a microscope. The amount of adhesion was evaluated. However, in each example, the condition is that no debris is attached to the thermal head at the time of the first printing start. Thermal head residue tends to occur at the part where the thermal transfer sheet hits both sides of the thermal transfer sheet, so the judgment was made in the thermal head where the thermal head deposits hit the both sides of the thermal transfer sheet. The case where it was generated to cover the heater line was marked as x, and the case where it was not so large as to cover the heater line was marked as ◯.

Further, the frictional force between the thermal head and the thermal transfer sheet was measured by the following method.
As shown in FIG. 4, the thermal transfer printer 10 with a frictional force measurement function includes a printer main body 10 a that is swingably supported by a support shaft 12, a thermal head 11 attached to the printer main body 10 a, and a thermal head 11. And a platen roller 14 provided. Among these, the printer main body 10a has a substantially triangular shape centered on the support shaft 12, and the thermal head 11 is provided at the lower end A of the printer main body 10a and swings near the right end C of the printer main body 10a. A detection unit 13 is provided in contact with the main body 10a to obtain the swinging force of the printer main body 10a. The support shaft 12 of the printer body 10a is disposed at the point B.

The platen roller 14 is pressed toward the thermal head 14 by a pressing mechanism 18 provided on the base 20 so that the thermal transfer sheet 16 and the photographic paper 17 are sandwiched between the thermal head 14 at a constant pressure. Among these, the thermal transfer sheet 16 includes a base film, a dye layer (thermal transferable color material layer) provided on one side of the base film, and a heat resistant slipping layer provided on the other side of the base film. The dye layer can be transferred to the transfer target 17 side by heating with a thermal head from the heat resistant slipping layer side. When the thermal transfer sheet 16 and the transfer target 17 are conveyed in the direction of arrow L _{1 in} FIG. 4, the printer body 10 a swings in the direction of arrow L ₂ about the support shaft 12 and contacts the detection unit 13. At this time, the swinging force of the printer main body 10a is obtained by the detection unit 13, a signal from the detection unit 13 is transmitted to the conditioner 13a, and the friction force between the thermal head 11 and the thermal transfer sheet 16 is transmitted by the conditioner 13a. Can be sought.

While the thermal head 11 repeats heating ON / OFF, a frictional force is generated between the thermal head 11 and the heat-resistant slip layer of the thermal transfer sheet 16. With such frictional force between the heat-resistant lubricating layer of the thermal head 11 and the thermal transfer sheet 16 occurs, the printer main body 10a is swung in the arrow L ₂ direction in FIG. 4 about the support shaft 12, the printer body 10a Comes into contact with the detection unit 13. At this time, the detection unit 13 detects the swinging force of the printer body 10a.

  As shown in FIG. 4, the distance between the thermal head 11 provided at the lower end (one end) A of the printer main body 10a and the support shaft 12 located at the point B is AB, and the right end ( When the distance between the other end portion C and the support shaft 12 is BC, the friction force between the thermal head 11 and the thermal transfer sheet 16 is caused by the conditioner 13a based on the swinging force obtained by the detection unit 13. , Friction force = oscillating force × (BC / AB).

  In the printer main body 10a of the thermal transfer printer 10, the relationship between the distance AB between the support shaft 12 and the lower end portion A and the distance BC between the support shaft 12 and the right end portion C is AB: BC = 1: 1. It has become. Further, ∠ABC is 90 °. Further, a strain gauge type LM-5KA-P (manufactured by Kyowa Denki, capacity 50 N, rated output 1.005 mV / V) was used as the detection unit 13. As a conditioner 13a connected to the detection unit 13, a DC bridge power supply type CDV-700A (manufactured by Kyowa Denki Co., Ltd.) having excellent high frequency response was used. Finally, the output from the conditioner 13a was weighted to obtain the frictional force.

  The feeding speed of the transfer target 17 and the thermal transfer sheet 16 was set to 84 μm / line, and the printing pressure was set to 30 [N]. The resistance value of the thermal head was 1586 ohm / dot, and the number of heating elements of the thermal head was 720 dots (60.5 mm width). The additional voltage was 13.2V. As shown in FIG. 3, only 768 lines were energized to the thermal head 11, the number of gradations was controlled in 12 steps from 0 to 11 gradations, and the pulse duty was 80% at 11/11 gradations. The actual print pattern was made to be a solid and white stripe (printed portion and non-printed portion) in a direction perpendicular to the transfer direction of the transfer object. The printing speed is 4 msec / line, and the thermal head temperature before printing is 30 ° C. Furthermore, an image receiving sheet for CP730 manufactured by Canon Inc. was used as a transfer target. The measurement of the frictional force between the thermal head and the thermal transfer sheet is based on the method described in Japanese Patent Laid-Open No. 2003-300338.

Table 1 shows the evaluation results of the deviation amount of the print and the thermal head residue, and the measurement results of the frictional force between the thermal head and the thermal transfer sheet measured by the above method.

It is a schematic sectional drawing which shows one embodiment of the thermal transfer sheet of this invention. FIG. 5 is a schematic diagram illustrating a point in which a print length shift occurs between hues when images with different print ratios are printed with different hues, illustrating a conveyance state of a thermal transfer sheet, a thermal head, a transfer target, and the like. When printing images with different hues in different hues, the print length shift between hues is indicated for each card of the transfer object, indicating the print start and print end, specifying the print pattern, It is the schematic to explain. . It is the schematic explaining the apparatus and method which measures the frictional force of a thermal head and a thermal transfer sheet at the time of heating of a thermal head, and the time of non-heating (ON / OFF).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal transfer sheet 2 Base material sheet 3 Thermal transfer color material layer 4 Heat resistant slipping layer 5 Thermal head 6 Platen roll 7 Thermal transfer image receiving sheet (transfer object)
DESCRIPTION OF SYMBOLS 10 Thermal transfer printer 10a Printer main body 11 Thermal head 12 Support shaft 13 Detection part 14 Platen roller 15 Release plate 16 Thermal transfer sheet 17 Transfer object 18 Pressing mechanism 20 Base

Claims (5)

  In the thermal transfer sheet in which at least two thermal transfer colorant layers are sequentially formed on one surface of the substrate sheet and the heat resistant slipping layer is formed on the other surface of the substrate sheet, The functional layer contains a hydroxyl group-containing thermoplastic resin, polyisocyanate, phosphate ester-based surfactant, and high-density polyethylene wax particles, and the content of the high-density polyethylene wax in the heat-resistant slip layer is 0.5 to 8 mass. The high-density polyethylene wax is a spherical particle having a melting point of 110 ° C. or more and 140 ° C. or less and an average particle size of 7 to 12 μm.   The thermal transfer sheet according to claim 1, wherein the hydroxyl group-containing thermoplastic resin is a polyvinyl acetal resin.   The thermal transfer sheet according to claim 1 or 2, wherein the heat-resistant slipping layer contains inorganic or organic fine particles.   The thermal transfer sheet according to any one of claims 1 to 3, wherein the thermal transfer color material layer includes at least a yellow color material layer, a magenta color material layer, and a cyan color material layer. The thermal transfer sheet according to claim 1, wherein the thermal transfer sheet is for card making.

Images