JP5288174B2 - Thermal transfer sheet - Google Patents

Description

  The present invention relates to a thermal transfer sheet. More specifically, a thermal transfer colorant layer is formed on one surface of a base film, and a heat resistant primer layer and a heat resistant slipping layer are provided in this order from the base film on the other surface. The present invention relates to a heat transfer sheet having a heat resistance in which a heat resistant primer layer is formed from a specific material and wrinkles due to printing are improved.

  Conventionally, various thermal transfer recording methods are known. Among them, a thermal transfer sheet having a dye layer in which a dye for sublimation transfer is used as a recording material and this is supported on a base material such as a polyester film with a suitable binder. From the above, there are proposed methods for forming various full-color images by thermally transferring a sublimation dye onto a transfer material that can be dyed with a sublimation dye, for example, a thermal transfer image-receiving sheet having a dye-receiving layer formed on paper or a plastic film. Yes. In this case, as the heating means, the color dots having a large number of three or four colors adjusted by heating with the thermal head of the printer are transferred to the receiving layer of the thermal transfer image receiving sheet, and the multicolored color dots are transferred. To reproduce the full color of the document. The image formed in this way is very clear and excellent in transparency because the coloring material used is a dye, so the resulting image is excellent in the reproducibility and gradation of intermediate colors, It is possible to form a high-quality image similar to an image obtained by offset printing or gravure printing and comparable to a full-color photographic image.

  In such a thermal transfer recording system using sublimation transfer, as the printing speed of the thermal transfer printer is increased, there has been a problem that a sufficient print density cannot be obtained with the conventional thermal transfer sheet. Also, there has been a demand for higher density and clearer prints of thermal transfer images, and improved thermal transfer image-receiving sheets that accept images of sublimation dyes transferred from the thermal transfer sheet and the thermal transfer sheet. Many attempts have been made. For example, attempts have been made to improve transfer sensitivity in printing by reducing the thickness of the thermal transfer sheet, but wrinkles may occur due to heat, pressure, etc. during manufacture of the thermal transfer sheet or during thermal transfer recording. Causes the problem of cutting.

  When high density printing is performed with a conventional thermal transfer sheet, if the high temperature above the melting point of the plastic is applied to the plastic film of the base film from the thermal head, the base film loses heat and wrinkles on the thermal transfer sheet. As a result, image unevenness due to the wrinkles occurs in the printed image. It has been proposed to form a layer (heat resistant slipping layer) containing various heat resistant resins on the surface opposite to the surface of the heat transfer colorant layer of the base film so that wrinkles do not occur in such a heat transfer sheet. .

  For example, Patent Document 1 describes that a heat-resistant slip layer of a thermal transfer sheet is crosslinked with a heat-crosslinkable polymer that is a heat-resistant resin to improve heat resistance. Further, Patent Document 2 describes that the heat resistance is improved by crosslinking an electron beam crosslinkable polymer, which is a heat resistant resin, on the heat resistant slipping layer of the thermal transfer sheet. Patent Document 3 describes that the heat-resistant slip layer of the thermal transfer sheet is crosslinked with an ultraviolet-crosslinkable polymer that is a heat-resistant resin to improve heat resistance.

  However, in these methods, if the layer thickness is increased in order to obtain the desired performance, a large amount of energy is required to cure the heat resistant resin, and as a result, heat is applied to the base film of the thermal transfer sheet. There was a problem that deformation occurred. In addition, as a thermal transfer image receiving sheet, a card form using a plastic sheet as a base material, the base material itself having a dyeing property, or an image receiving sheet provided with a dye receiving layer on the base material is used. When using the above card, when the thermal pressure is applied with the thermal transfer sheet and thermal transfer image-receiving sheet overlaid and sandwiched between the thermal head and the platen (roll), In order to eliminate unevenness, in particular, the applied pressure is increased and the pressure is applied directly to the thermal transfer sheet, and the thermal transfer sheet is wrinkled, or friction between the thermal transfer sheet and the thermal transfer sheet. There is a problem with the running of the car.

  For example, Patent Document 4 discloses a primer layer containing a sulfonated polyaniline as an antistatic agent and a resin having a specific viscoelasticity as a primer component between the base sheet and the heat-resistant slipping layer. Proposed to provide. However, the card-type image receiving sheet using a plastic sheet as a base material still has a problem that the thermal transfer sheet is wrinkled during printing.

JP-A-6-278373 JP-A-6-171248 Japanese Patent Laid-Open No. 2-128899 JP 2001-1653 A

  Therefore, in order to solve the above problems, the object of the present invention is to provide a thermal transfer sheet in which a heat transferable color material layer is formed on one surface of a base film and a heat resistant slipping layer is formed on the other surface. Provided is a thermal transfer sheet having a heat resistance primer layer provided between a base film and a heat resistant slip layer, having excellent adhesion between the heat resistant slip layer and the base film, and preventing wrinkles caused by printing. That is.

The above object is achieved by the present invention described below. That is, the present invention is a thermal transfer in which at least two or more heat transferable color material layers are formed in a surface sequence on one surface of a substrate film, and a heat resistant slipping layer is formed on the other surface of the substrate film. In the sheet, a heat-resistant primer layer is provided between the base film and the heat-resistant slipping layer, and the heat-resistant primer layer is a copolymer (A) mainly composed of acrylic acid monomer or a copolymer composed mainly of methacrylic acid monomer. Containing a polymer (B), the copolymer (A) or the copolymer (B) has a Tg of 30 ° C. or more and 80 ° C. or less, and a weight average molecular weight of 40,000 or more and 300,000 or less. Ah it is, and the heat-resistant slip layer is a hydroxyl group-containing thermoplastic resin and a polyisocyanate, phosphoric acid ester-based surfactant and includes a high density polyethylene wax particles, put on the heat-resistant lubricating layer of the The content of the high density polyethylene wax 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, The thermal transfer sheet is for card production .

  If the Tg is too low, tackiness occurs when the thermal transfer sheet is stored, and problems such as blocking occur. Moreover, when said Tg is too high, a film | membrane will be hard and adhesiveness with a base film will worsen. Further, since the film is hard, it is difficult to be elastically deformed, and the stress between the thermal head and the base film cannot be relaxed, and wrinkles are likely to occur. Moreover, when the weight average molecular weight of the copolymer which comprises a heat-resistant primer layer is too small, it will be easy to cohesive failure and adhesiveness with a base film will worsen. On the other hand, when the weight average molecular weight of the copolymer is high, the viscosity becomes high and the coating suitability is lowered.

The heat resistant slipping layer contains a hydroxyl group-containing thermoplastic resin, polyisocyanate, phosphate surfactant, and high density polyethylene wax particles, and the content of the high density polyethylene wax in the heat resistant slipping layer is 0.00. 5-8 is the mass%, high-density polyethylene wax has a melting point of 110 ° C. or higher 140 ° C. or less, the average particle diameter of spherical particles 7～12Myuemu, friction between the thermal head and the heat resistant lubricating layer The difference in the frictional force between when the thermal head is heated and when the thermal head is not heated is small, and it has slipperiness, and the running property of the thermal transfer sheet in the printer during printing is stabilized.

The thermal transferable color material layer preferably includes at least a yellow color material layer, a magenta color material layer, and a cyan color material layer, and a full-color print can be formed by using only one thermal transfer sheet. The thermal transfer sheet of the present invention is for card production, and is applied especially when heated by a thermal head in order to eliminate uneven printing when using a card as an image receiving sheet which is a transfer target used in combination. Even if the pressure increases, if the thermal transfer sheet of the present invention is used, the heat-resistant primer layer contains a copolymer mainly composed of acrylic acid monomer, or a copolymer mainly composed of methacrylic acid monomer. This heat-resistant primer layer was highly elastic and could not directly damage the base film of the thermal transfer sheet. As a result, it is possible to prevent the thermal transfer sheet from being wrinkled during printing.

  A heat-resistant primer layer is provided between the base film of the thermal transfer sheet and the heat-resistant slipping layer, and the heat-resistant primer layer is a copolymer (A) mainly composed of acrylic acid monomer or a copolymer composed mainly of methacrylic acid monomer. Containing a polymer (B), the copolymer (A) or the copolymer (B) has a Tg of 30 ° C. or more and 80 ° C. or less, and a weight average molecular weight of 40,000 or more and 300,000 or less. As a result, it is possible to obtain a heat transfer sheet having a heat transfer sheet that has good adhesion to the base film (mainly polyester film) of the heat transfer sheet and prevents wrinkles due to printing. In addition, the thermal transfer sheet has a high elasticity and excellent heat resistance even when the conditions of heating and pressurization at the time of printing become severe. It is possible to prevent the thermal transfer sheet from being wrinkled during printing.

Next, an embodiment of the invention will be described in detail.
FIG. 1 shows one embodiment which is a thermal transfer sheet of the present invention. A heat-resistant primer layer 2 and a heat-resistant slip layer 3 are sequentially laminated on one surface of the base film 1, and a yellow color material layer 41 as a heat transferable color material layer 4 is formed on the other surface of the base film 1. In this configuration, the magenta color material layer 42 and the cyan color material layer 43 are repeatedly provided in the surface order.
Below, each layer which comprises the thermal transfer sheet of this invention is demonstrated in detail.

(Base film)
The base film 1 constituting the thermal transfer sheet of the present invention may be any film as long as it has a conventionally known degree of heat resistance and strength, for example, 0.5 to 50 μm, preferably about 3 to 10 μm. Polyethylene terephthalate film, 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, In addition to resin films such as cellulose derivatives such as cellulose acetate, polyethylene film, polyvinyl chloride film, nylon film, polyimide film, ionomer film In addition, paper such as condenser paper and paraffin paper, nonwoven fabric, or a composite of paper or nonwoven fabric and resin may be used.

(Heat resistant primer layer)
In the present invention, a heat-resistant primer layer 2 containing a copolymer mainly composed of an acrylic acid monomer or a copolymer mainly composed of a methacrylic acid monomer is provided between the base film and the heat-resistant slipping layer. It is. Examples of the copolymer mainly composed of the acrylic acid monomer include a copolymer of an acrylic acid monomer and a fumaric acid monomer, or a resin in which polyacrylic acid and maleic anhydride are mixed. Examples of the copolymer mainly composed of the methacrylic acid monomer include a copolymer of a methacrylic acid monomer and an itaconic acid monomer.

  The above-mentioned copolymers mainly composed of acrylic acid monomers or copolymers mainly composed of methacrylic acid monomers are generally called acrylic resins, but acrylic resins are obtained by polymerizing acrylic acid and its derivatives. Resins that can be used, including polymers such as acrylic acid, acrylic ester, acrylamide, acrylonitrile, methacrylic acid, methacrylic ester, and copolymers with other monomers such as styrene. The dicarboxylic acid has two carboxyl groups, and examples thereof include maleic acid, fumaric acid, itaconic acid, and acid anhydrides thereof. A copolymer obtained by copolymerizing such an acrylic resin as a monomer with a dicarboxylic acid can be preferably used in the heat-resistant primer layer of the present invention. In addition, a mixture of an acrylic resin and a dicarboxylic acid, and the acrylic resin and the dicarboxylic acid are not chemically bonded to each other, but a mixture of the acrylic resin and the dicarboxylic acid is also used as the heat-resistant primer of the present invention. It can be preferably used in a layer.

  When the acrylic resin is copolymerized with a dicarboxylic acid as a monomer, it is preferable that the acrylic acid and the dicarboxylic acid have a molar fraction of dicarboxylic acid of 0.001 to 0.4 and the remainder is acrylic acid. When the amount of dicarboxylic acid is small, the adhesiveness between the heat-resistant primer layer and the base film is lowered, which is not preferable. Moreover, when there are many dicarboxylic acids, it is easy to generate | occur | produce wrinkles by a printing, and it is unpreferable. Moreover, when mixing dicarboxylic acid with an acrylic resin, it is preferable to mix 0.1-60 mass parts of dicarboxylic acid with respect to 100 mass parts of acrylic resins. If the amount of dicarboxylic acid is small, the adhesion between the heat-resistant primer layer and the base film is lowered, and the heat-resistant primer layer is peeled off from the base film, which is not preferable. On the other hand, when the amount of dicarboxylic acid is large, the heat resistance is lowered, so that wrinkles due to printing tend to occur, which is not preferable.

  The copolymer mainly composed of the acrylic acid monomer or the copolymer mainly composed of the methacrylic acid monomer preferably has a Tg of 30 ° C. or higher and 80 ° C. or lower. If the Tg is less than 30 ° C., tackiness occurs when the thermal transfer sheet is stored, and problems such as blocking are likely to occur. Moreover, when said Tg exceeds 80 degreeC, a film | membrane will become hard and adhesiveness with a base film will worsen. Further, since the film is hard, it is difficult to be elastically deformed, and the stress between the thermal head and the base film cannot be relaxed, and wrinkles are likely to occur. All Tg prescribed | regulated by this invention are measured by DSC (differential calorimeter) generally known.

  In addition, a copolymer having a weight average molecular weight of 40,000 or more and 300,000 or less is preferably used for the copolymer mainly composed of acrylic acid monomer or the copolymer mainly composed of methacrylic acid monomer. When the weight average molecular weight of the copolymer constituting the heat-resistant primer layer is less than 40000, the heat-resistant primer layer tends to cohesively break and adhesion to the substrate film is deteriorated. On the other hand, when the weight average molecular weight of the copolymer is larger than 300,000, the viscosity of the coating solution for forming the heat-resistant primer layer containing the resin increases, and the coating suitability decreases. The weight average molecular weight defined in the present invention was measured by GPC (gel permeation chromatography, the solvent was tetrahydrofuran).

  In addition to the above-mentioned acrylic resin copolymerized or mixed with dicarboxylic acid, it is not particularly limited as long as it has heat resistance, and a thermoplastic resin or a thermosetting resin alone or a mixture may be added. In order to further improve heat resistance, reaction products with various isocyanate curing agents, monomers having unsaturated bonds, and oligomers may be used, and the curing method is not particularly limited, such as heating and irradiation with ionizing radiation. Various modified resins obtained by modifying the binder resin with silicone or long-chain alkyl can also be used.

  Examples of binder resins that can be used in addition to those obtained by copolymerizing or mixing dicarboxylic acids with acrylic resins include, for example, polyester resins, polyvinyl acetate resins, polyurethane resins, norbornene resins, polyolefin resins, polystyrene resins, and polyresins. Examples thereof include thermoplastic resins such as polyvinyl acetal resins such as vinyl chloride resins, polyether resins, polyamide resins, polycarbonate resins, polyethylene resins, polypropylene resins, polyvinyl chloride resins, polyvinyl butyral resins, and polyvinyl acetoacetal resins. Examples of the modified resin include commercially available various modified silicone resins and resins obtained by reacting a resin having a hydroxyl group with an isocyanate-modified monovalent higher alcohol, such as an acetal resin.

As a method for forming a heat-resistant primer layer, a coating liquid is prepared by dissolving or dispersing in water or a solvent such as acetone, methyl ethyl ketone, toluene, xylene, etc., selected so as to suit the coating suitability of the above materials, Examples of the method include forming a film by applying, drying and solidifying the coating solution by a conventional coating means such as a gravure coater, a roll coater, a wire bar or the like. As a coating amount, i.e. the thickness of the heat-resistant primer layer may have 5.0 g / m ² or less on a solids basis, heat preferably has a thickness of 0.1 to 2.0 g / m ^2, sufficient performance A slipping layer can be formed.

(Heat resistant slipping layer)
The heat-resistant slip layer 3 is formed for the purpose of improving the running performance and heat resistance of the thermal head during printing. Examples of the binder resin that forms the heat resistant slipping layer include a thermoplastic resin and a thermosetting resin or a cross-linked product thereof. As a preferable thermoplastic resin, known resins can be used, for example, polyester resins, polyacrylate resins, polyvinyl acetate resins, polyurethane resins, styrene acrylate resins, polyacrylate resins, polyacrylamide resins. , Polyamide resins, polyether resins, polystyrene resins, polyethylene resins, polypropylene resins, polyolefin resins, vinyl resins such as polyvinyl chloride resins and polyvinyl alcohol resins, cellulose resins, hydroxyethyl cellulose resins, cellulose acetate resins And cellulose-based resins such as polyvinyl acetoacetal resins and polyvinyl butyral resins, silicone-modified resins, and long-chain alkyl-modified resins. Particularly preferred resins in the present invention are hydroxyl group-containing thermoplastic resins such as polyvinyl acetal resins such as polyvinyl acetoacetal resin and polyvinyl butyral resin, polyvinyl acetate resins and polyester resins.

  It is preferable to use a reaction cured product of a thermoplastic resin containing a hydroxyl group as the reactive group and a polyisocyanate as a binder resin for the heat resistant slipping layer. Adhesiveness with a base film can be improved. The polyisocyanate may be a polyisocyanate that has been conventionally used for the synthesis of paints, adhesives, or polyurethanes.

  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 (isocyanatephenyl) 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.

  These polyisocyanates include, for example, Takenate (manufactured by Takeda Pharmaceutical Co., Ltd.), Barnock (manufactured by Dainippon Ink and Chemicals Co., Ltd.), Coronate (manufactured by Nippon Polyurethane Industry Co., Ltd.), Duranate (manufactured by Asahi Kasei Kogyo Co., Ltd.), Dismodule It can be obtained under a trade name such as (manufactured by Bayer) and used in the present invention. The addition amount of the polyisocyanate is suitably in the range of 5 to 200 parts by mass with respect to 100 parts by mass of the binder resin constituting the heat resistant slipping layer. The -NCO / -OH ratio is preferably in the range of 0.6 to 2.0. When the amount of polyisocyanate used is insufficient, the heat resistance is insufficient because the crosslinking density is low. On the other hand, if the amount is too large, the shrinkage of the formed coating film cannot be controlled, and the curing time is prolonged, unreacted- NCO groups may remain in the slipping layer and cause problems such as reaction with moisture in the atmosphere.

As a slipperiness imparting agent (lubricant) to be added to the heat resistant slipping layer for improving the slipperiness, various conventionally known lubricants can be used. However, sufficient slipperiness especially when heated by a thermal head (printing). It is preferable to add a phosphate ester surfactant that can be provided. As the phosphate ester surfactant,
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 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.

  In the present invention, the addition of high-density polyethylene wax particles is preferable because the lubricity of the heat-resistant slipping layer when not heated can be improved. 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, 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.

  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 in a ratio of 5 to 40 parts by mass with respect to 100 parts by mass of the thermoplastic resin. If the addition amount is too small, the slipperiness is insufficient, and on the other hand, it is too much. The flexibility and film strength of the heat-resistant slip layer formed are reduced. In order to provide the heat resistant slipping layer on the base film, 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 film with the usual appropriate 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 slip layer is a coating weight of ^{solids, 0.5g / m 2 ~5.0g / m} 2, and preferably from ^{1.0g / m 2 ~2.0g / m 2} . When this film thickness is less than 0.5 g / m ² , the effect as a heat-resistant slip layer is not sufficient, and when it is thicker than 5.0 g / m ² , the thermal head to the heat transferable color material layer Heat transfer becomes worse, and the printing density is lowered. When a heat resistant slipping layer is provided on the base film, 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)
When the heat transferable color material layer 4 formed on the other surface of the heat resistant primer layer and the heat resistant slipping layer of the base film is a sublimation type heat transfer sheet, a layer containing a sublimation dye is used. In the case of a heat melting type thermal transfer sheet, a layer is formed with a heat melting ink colored with a pigment or the like. Hereinafter, although a sublimation type thermal transfer sheet will be described in detail as a representative example, the present invention is not limited to only a sublimation type thermal transfer sheet.

  As the dye used in the sublimation type heat transferable color material layer, any dye conventionally used in known heat transfer sheets can be used in the present invention and is not particularly limited. These dyes include methines such as diarylmethane, triarylmethane, thiazole and merocyanine, indoaniline, azomethine such as acetophenone azomethine, pyrazoloazomethine, imidazole azomethine and pyridone azomethine, xanthene and oxazine. Cyanomethylene, thiazine, azine, acridine, benzeneazo, and pyridoneazo, thiophenazo, isothiazoleazo, pyrroleazo, pyrazoleazo, imidazoleazo, thiadiazoleazo, triazoleazo represented by dicyanostyrene and tricyanostyrene Azo, such as, disazo, spiropyran, indolinospiropyran, fluoran, rhodamine lactam, naphthoquinone, anthraquinone, quinophthalone It is. Specifically, the following dyes are used.

C. I. (Color Index) Disperse Yellow 51, 3, 54, 79, 60, 23, 7, 141, 201, 231
C. I. Disperse Blue 24, 56, 14, 301, 334, 165, 19, 72, 87, 287, 154, 26, 354
C. I. Disperse thread 135, 146, 59, 1, 73, 60, 167
C. I. Disperse Orange 149
C. I. Disperse violet 4, 13, 26, 36, 56, 31
C. I. Solvent Yellow 56, 14, 16, 29
C. I. Solvent Blue 70, 35, 63, 36, 50, 49, 111, 105, 97, 11
C. I. Solvent Red 135, 81, 18, 25, 19, 23, 24, 143, 146, 182
C. I. Solvent Violet 13
C. I. Solvent Black 3
C. I. Solvent Green 3

  For example, Foron brilliant yellow S-6GL (Sand, Disperse Yellow 231), Macrolex Yellow 6G (Bayer, Disperse Yellow 201) as a yellow dye, MS-RED-G (Mitsui Toatsu Chemical Co., Ltd.) as a magenta dye Company, Disper Thread 60), Macrolex Red Violet R (manufactured by Bayer, Dispers Violet 26), cyan dye is Kayaset Blue 714 (Nippon Kayaku Co., Ltd., Solvent Blue 63), Foron Brilliant Blue S-R (Sand, Disperse Blue 354), Waxoline Blue AP-FW (ICI, Solvent Blue 36) and the like.

  Next, as a binder resin for carrying the above dye, cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, acetic acid / butyric acid cellulose, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl Examples include vinyl resins such as acetoacetal and polyvinylpyrrolidone, acrylic resins such as poly (meth) acrylate and poly (meth) acrylamide, polyurethane resins, polyamide resins, and polyester resins. Among these, cellulose , Polyurethane-based, vinyl-based, acrylic-based and polyester-based resins are preferably used in terms of heat resistance, dye transferability and the like.

The dye layer, which is a sublimation-type heat transferable color material layer, adds these dyes and a binder resin, and additives (for example, release agents, etc.), fillers, and the like as necessary to one surface of the base film. And dissolved in an appropriate organic solvent such as toluene, methyl ethyl ketone, ethanol, isopropyl alcohol, cyclohexanone, DMF, or dispersed in an organic solvent or water, for example, gravure printing, screen printing, reverse roll coating printing A coating film can be formed by coating and drying by means such as a method. Dye layer formed in this way, in the coating amount in thickness, in the dry state, 0.2~5.0g / m ² preferably has a thickness of about 0.4 to 2.0 g / m ² The sublimable dye in the dye layer should be present in an amount of 5 to 90% by mass, preferably 10 to 70% by mass, based on the mass of the dye layer. If the image of the desired heat transferable color material layer is monocolor, it is formed by selecting one of the dye layers such as yellow, magenta, and cyan. If the image is a full color image, suitable yellow, magenta , And cyan (add black if necessary) to form each dye layer.

  The heat transferable color material layer described above is required to form at least two or more heat transferable color material layers of different hues in the surface order on the base film, but the two or more heat transferable color material layers are required. The conditions of the above are that two or more dye layers using a sublimable dye are formed, a combination of a dye layer and a heat transferable color material layer of a heat-meltable ink, or two heat-transferable color material layers of a heat-meltable ink. There may be more than one. Particularly in the present invention, a yellow dye layer, a magenta dye layer, and a cyan dye layer are formed in the surface order as a heat transferable color material layer containing a sublimation dye on the base sheet, and high quality thermal transfer comparable to a full color photographic image. It is preferable to form a clear image in which an 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 to add a color material layer made of black heat-meltable ink using a black colorant to the base film. As a result, a clear image having a high black density can be obtained.

In order to improve the adhesion between the base film and the heat transferable color material layer, an easy-adhesion layer obtained by longitudinal stretching and then individually or a mixture of a polyester resin and an acrylic resin and cured with a melamine crosslinking agent May be applied. However, the coating amount of the easy-adhesion layer is preferably 0.1 g / cm ² or less in a dry state, and the coating amount unevenness is preferably within a range of ± 15% in both the vertical direction and the width direction. The surface treatment of the base film, that is, the easy adhesion treatment may be performed by corona treatment, plasma treatment, or the like without being limited to the method of applying the easy adhesion layer.

(Transfer material)
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 that is a white plastic sheet containing a white pigment.

Next, the present invention will be described more specifically with reference to examples. Hereinafter, unless otherwise specified, parts or% is based on mass.
( Reference Example 1)
Using a bar coater, apply the following heat-resistant primer layer coating liquid 1 at a rate of 0.8 g / m ^{2 in} terms of solid content on one side of a 6 μm thick easy-adhesion-treated polyethylene terephthalate film. And dried at 90 ° C. for 1 minute to form a heat-resistant primer layer. Moreover, the following heat resistant slipping layer coating liquid 1 was applied onto the heat resistant primer layer at a rate of 1.0 g / m ^{2 in} terms of solid content and dried at 90 ° C. for 2 hours to form a heat resistant slipping layer.

<Heat-resistant primer layer coating solution 1>
-Acrylic resin 15.0 parts (BR-64 weight average molecular weight: 65000, Tg: 55 ° C., manufactured by Mitsubishi Rayon Co., Ltd.)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

<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 ・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

A yellow dye layer (Y), a magenta dye layer (M), and a cyan dye layer (C) are repeatedly formed in this order on the other surface of the base sheet (on the easy adhesion treatment surface) in this order by a bar coater. did. Each dye layer (Y, M, C) is coated with the following coating liquid for each dye layer (Y, M, C) at a rate of 1.0 g / m ^{2 in} terms of solid content using a bar coater. And dried to prepare the thermal transfer sheet of Reference Example 1.

<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

( Reference Example 2)
The heat-resistant primer layer coating solution in Example 1, except that the heat-resistant coating solution for a primer layer 2 below, in the same manner as in Reference Example 1 to prepare a thermal transfer sheet of Example 2.
<Heat-resistant primer layer coating solution 2>
-Acrylic resin 15.0 parts (BR-105 weight average molecular weight: 55000, Tg: 50 ° C., manufactured by Mitsubishi Rayon Co., Ltd.)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

( Reference Example 3)
The heat-resistant primer layer coating solution in Example 1, except that the heat-resistant coating solution for a primer layer 3 below, in the same manner as in Reference Example 1 to prepare a thermal transfer sheet of Example 3.
<Heat-resistant primer layer coating solution 3>
-Acrylic resin 10.0 parts (BR-101 weight average molecular weight: 160000, Tg: 50 ° C., manufactured by Mitsubishi Rayon Co., Ltd.)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

( Reference Example 4)
The heat-resistant primer layer coating solution in Example 1, except that the heat-resistant coating solution for a primer layer 4 below, in the same manner as in Reference Example 1 to prepare a thermal transfer sheet of Example 4.
<Heat-resistant primer layer coating solution 4>
-Acrylic resin 15.0 parts (BR-116 weight average molecular weight: 45000, Tg: 50 ° C., manufactured by Mitsubishi Rayon Co., Ltd.)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

( Reference Example 5)
The heat-resistant primer layer coating solution in Example 1, except that the heat-resistant coating solution for a primer layer 5 below, in the same manner as in Reference Example 1 to prepare a thermal transfer sheet of Example 5.
<Heat-resistant primer layer coating solution 5>
-Acrylic resin 10.0 parts (BR-90 weight average molecular weight: 230000, Tg: 65 ° C., manufactured by Mitsubishi Rayon Co., Ltd.)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Example 1 )
The heat-resistant lubricating layer coating liquid in Example 1, except that the coating liquid 2 for the heat-resistant lubricating layer below, in the same manner as in Reference Example 1 to prepare a thermal transfer sheet of Example 1.
<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 parts ・ Spherical high-density polyethylene wax (solid content ratio: 0.5 mass%) * 1 0.09 parts (melting point: 110 to 118 ° C., (Average particle size 10μm)
-Methyl ethyl ketone 100.0 parts-Toluene 100.0 parts * 1; The numerical value of solid content ratio in polyethylene wax is the mass% with respect to the total solid content (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.

(Example 2 )
The heat-resistant lubricating layer coating liquid in Example 2, except that the coating liquid 2 for the above heat-resistant slipping layer, in the same manner as in Reference Example 2, to prepare a thermal transfer sheet of Example 2.

(Comparative Example 1)
The heat-resistant primer layer coating solution in Example 1, except that the heat-resistant coating solution for a primer layer 6 below, in the same manner as in Reference Example 1 to prepare a thermal transfer sheet of Comparative Example 1.
<Heat-resistant primer layer coating solution 6>
-Acrylic resin 15.0 parts (BR-83 weight average molecular weight: 40000, Tg: 105 ° C., manufactured by Mitsubishi Rayon Co., Ltd.)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Comparative Example 2)
The heat-resistant primer layer coating solution in Example 1, except that the heat-resistant coating solution for a primer layer 7 below, in the same manner as in Reference Example 1 to prepare a thermal transfer sheet of Comparative Example 2.
<Heat-resistant primer layer coating solution 7>
-Acrylic resin 10.0 parts (BR-88 weight average molecular weight: 480000, Tg: 105 ° C., manufactured by Mitsubishi Rayon Co., Ltd.)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Comparative Example 3)
The heat-resistant primer layer coating solution in Example 1, except that the heat-resistant coating solution for a primer layer 8 below, in the same manner as in Reference Example 1 to prepare a thermal transfer sheet of Comparative Example 3.
<Heat-resistant primer layer coating solution 8>
-Acrylic resin 10.0 parts (BR-95 weight average molecular weight: 320,000, Tg: 80 ° C., manufactured by Mitsubishi Rayon Co., Ltd.)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Comparative Example 4)
The heat-resistant primer layer coating solution in Example 1, except that the heat-resistant coating solution for a primer layer 9 below, in the same manner as in Reference Example 1 to prepare a thermal transfer sheet of Comparative Example 4.
<Heat-resistant primer layer coating solution 9>
-Acrylic resin 10.0 parts (BR-102 weight average molecular weight: 360,000, Tg: 20 ° C., manufactured by Mitsubishi Rayon Co., Ltd.)
・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts

(Comparative Example 5)
The heat-resistant primer layer coating solution in Example 1, except that the heat-resistant coating solution for a primer layer 10 below, in the same manner as in Reference Example 1 to prepare a thermal transfer sheet of Comparative Example 5.
<Heat-resistant primer layer coating solution 10>
・ 10 parts of aqueous polyester resin (Polyester WR-960, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
・ 45 parts of water ・ 45 parts of isopropyl alcohol

(Comparative Example 6)
The heat-resistant primer layer coating solution in Example 1, except that the heat-resistant coating solution for a primer layer 11 below, in the same manner as in Reference Example 1 to prepare a thermal transfer sheet of Comparative Example 6.
<Heat-resistant primer layer coating solution 11>
・ Polyvinylpyrrolidone resin (K-15, manufactured by ISP) 6.0 parts ・ Water 47 parts ・ Isopropyl alcohol 47 parts

The thermal transfer sheets of the above Examples , Reference Examples and Comparative Examples were evaluated for the adhesion between the base film and the heat-resistant primer layer or the heat-resistant slip layer, and the printing wrinkles and the printing density. The evaluation method will be described below.
Evaluation method 1. An adhesive mending tape (Nichiban Nystack 12 mm wide) is cut out by 5 cm, and 3 cm of the tape is stuck on the heat-resistant slipping layer of each thermal transfer sheet. Thereafter, the tape was peeled 90 ° at a stretch, and it was visually confirmed whether the base film and the heat-resistant primer layer or the heat-resistant slipping layer were in close contact.

Judgment criteria for the evaluation of the adhesion are as follows.
○: The base film and the heat-resistant primer layer or heat-resistant slipping layer are in close contact, and nothing remains on the peeled tape.
(Triangle | delta): The adhesiveness of a base film and a heat resistant primer layer or a heat resistant slipping layer is a little inferior, and peeling of a layer is recognized a little in the peeled tape.
X: The base film and the heat-resistant primer layer or the heat-resistant slipping layer are not in close contact, and peeling of the layer is observed on the peeled tape.

2. Printing Wrinkles The thermal transfer sheet produced in each example was printed under the following printing conditions using the transfer target shown below, and the state of the printing wrinkles was evaluated with the naked eye.
<Printing conditions>
Transfer object: White vinyl chloride Card printer: Card printer
Printing pressure: 2.2kg / inch
Printing speed: 3msec / line
Thermal head resolution: 300 dpi
Print pattern: 255th gradation solid image
Printing energy: 0.26 mJ / dot

The criteria for evaluating print wrinkles are as follows.
○: No print wrinkles.
Δ: Fine print wrinkles at the edge of the printed material.
X: Print wrinkles are conspicuous on the printed material.

3. Print density The reflection density (maximum density) of the 255th gradation was measured for the prints in each of the above Examples , Reference Examples, and Comparative Examples, and the ratio of the density of each print product based on the print density of Comparative Example 1 Were ranked as follows.
○: Concentration is equivalent to the standard (concentration is 97% to 103%)
Δ: Concentration is 90 to 97% compared to standard
×: The concentration is less than 90% compared to the standard.

Table 1 shows the evaluation results of the above adhesion, printing wrinkles and printing density.

It is sectional drawing which shows one embodiment which is the thermal transfer sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base film 2 Heat resistant primer layer 3 Heat resistant slipping layer 4 Thermal transferable color material layer

Claims (2)

In a thermal transfer sheet in which at least two or more heat transferable color material layers are formed in a surface sequence on one surface of a base film, and a heat resistant slipping layer is formed on the other surface of the base film, the base film A heat-resistant primer layer is provided between the heat-resistant slipping layer and the heat-resistant primer layer contains a copolymer (A) mainly composed of acrylic acid monomer or a copolymer (B) mainly composed of methacrylic acid monomer. and, wherein the copolymer (a), or a copolymer relates to (B), the Tg is at 80 ° C. or less 30 ° C. or more and a weight average molecular weight of Ri der 40000 or 300000, and said The heat-resistant slipping layer contains a hydroxyl group-containing thermoplastic resin, polyisocyanate, phosphate ester-based surfactant, and high-density polyethylene wax particles, and the high-density polyethylene in the heat-resistant slipping layer described above. 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, and the thermal transfer sheet is A thermal transfer sheet for card production . The thermal transfer sheet according to claim 1, 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 .

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