JP5691684B2 - Thermal transfer recording medium - Google Patents

Description

  The present invention relates to a thermal transfer recording medium used in a thermal transfer type printer, and is provided with a heat-resistant slipping layer on one surface of a substrate, and an undercoat layer and a dye layer on the other surface of the substrate. Are sequentially formed. More specifically, the transfer sensitivity at the time of high-speed printing is high, that is, the dye used in the dye layer can be reduced, and the image quality defect occurring in the high density portion, that is, the image receiving layer of the transfer medium is applied to the thermal transfer recording medium. The present invention relates to a thermal transfer recording medium capable of reducing the phenomenon of so-called “shininess” in which hue fluctuation occurs by fusing, and as a result, the surface of a printed material is partially matted.

  In general, a thermal transfer recording medium is an ink ribbon called a thermal ribbon, which is used in a thermal transfer type printer, and has a thermal transfer layer on one side of the substrate and heat resistance on the other side of the substrate. A slipping layer (back coat layer) is provided. Here, the heat-sensitive transfer layer is an ink layer, and the ink is sublimated (sublimation transfer method) or melted (melt transfer method) by heat generated in the thermal head of the printer, and transferred to the transfer target side. is there.

  Currently, among the thermal transfer systems, the sublimation transfer system can easily form full-color images with various functions of the printer, so digital camera self-prints, cards such as identification cards, amusement output, etc. Widely used. Along with the diversification of such applications, there is a growing demand for smaller size, higher speed, lower cost, and durability for the printed material obtained. In recent years, durability has been given to the printed material on the same side of the base sheet. 2. Description of the Related Art Thermal transfer recording media having a plurality of thermal transfer layers provided so as not to overlap protective layers and the like that have been widely used have become quite popular.

  Under such circumstances, along with the diversification and widespread use of applications, there has arisen a problem that sufficient print density cannot be obtained with the conventional thermal transfer recording medium as the printing speed of the printer further increases. In order to increase the transfer sensitivity, attempts have been made to improve the transfer sensitivity in printing by reducing the thickness of the thermal transfer recording medium. However, wrinkles are caused by heat, pressure, etc. during the manufacture of the thermal transfer recording medium or during printing. It has a problem that it occurs or in some cases breaks.

  In addition, attempts have been made to increase the printing density and transfer sensitivity in printing by increasing the dye / resin (Dye / Binder) ratio in the dye layer of the thermal transfer recording medium. In addition to being up, a part of the dye migrates to the heat-resistant slipping layer of the thermal transfer recording medium during the winding state in the manufacturing process (setback), and when the rewinding is performed, the migrated dye has another color. When the dye layer or the protective layer is re-transferred (backside back) and the contaminated layer is thermally transferred to the transfer target, the hue becomes different from the designated color, or so-called scumming occurs.

  Attempts have also been made to increase the energy at the time of image formation on the printer side, not on the thermal transfer recording medium side, but not only the power consumption increases, but also the life of the thermal head of the printer is shortened. And the material to be transferred are fused, so that so-called abnormal transfer is likely to occur. On the other hand, when a large amount of a release agent is added to the dye layer or the transfer target in order to prevent abnormal transfer, blurring of the image or background staining may occur.

  In order to solve such a problem, several methods have been proposed. For example, Patent Document 1 proposes a thermal transfer sheet having an adhesive layer containing a polyvinylpyrrolidone resin and a modified polyvinylpyrrolidone resin between a base material and a dye layer.

  Patent Document 2 proposes a thermal transfer sheet having an adhesive layer composed of a thermoplastic resin of polyvinyl pyrrolidone resin or polyvinyl alcohol resin and colloidal inorganic pigment ultrafine particles between a substrate and a dye layer.

  Patent Document 3 proposes a thermal transfer sheet having a base layer composed of a copolymer of vinylpyrrolidone and vinyl acetate and colloidal inorganic pigment ultrafine particles between a base material and a dye layer.

JP-A-2005-231354 JP 2006-150956 A JP 2008-155612 A

  However, when printing is performed with a sublimation transfer type high-speed printer using the thermal transfer recording medium proposed in Patent Document 1, abnormal transfer is not confirmed, including those stored under high temperature and high humidity. The transfer sensitivity in printing was low, it did not reach a sufficient level, and shine could not be suppressed sufficiently. In addition, when printing is performed on the thermal transfer recording medium proposed in Patent Document 2, the transfer sensitivity in the printing is high and reaches a sufficient level, but is abnormally transferred when stored at high temperature and high humidity. Was confirmed, and the shine could not be suppressed sufficiently. Also, when printing is performed with the thermal transfer recording medium proposed in Patent Document 3, the transfer sensitivity in the printing is high and has reached a sufficient level. I could not. As described above, in the prior art, a thermal transfer recording medium that has high transfer sensitivity in printing, does not cause abnormal transfer even when stored under high temperature and high humidity, and can be used for a high-speed printer that sufficiently improves the phenomenon of shine. It is a situation where no has been found.

  Therefore, in view of the above problems, the present invention has high transfer sensitivity at the time of high-speed printing, that is, it can reduce the dye used for the dye layer, and also has abnormalities in printing even after storage under high temperature and high humidity. Transfer can be prevented, and image quality defects occurring at high density portions, that is, hue variation occurs when the image receiving layer of the transfer target is fused to the thermal transfer recording medium, and as a result, the surface of the print is partially It is an object of the present invention to provide a heat-sensitive transfer recording medium that can reduce the phenomenon of so-called “shininess” that causes matting.

The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 provides a heat-resistant slipping layer on one surface of a substrate and an undercoat layer on the other surface of the substrate. In the thermal transfer recording medium in which the dye layer is sequentially formed, the undercoat layer includes a silicon compound represented by the general formula Si (OR ¹ ) ₄ and / or a hydrolyzate thereof, and a general formula (NCO-R ⁴ Si (OR ³ ) ₃ ) ₃ trimer 1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate and / or a hydrolyzate thereof (provided that R ¹ and R ³ are CH ₃ , C ₂ H ₅ or C ₂ H ₄ OCH ₃ , R ⁴ is (CH ₂ ) _n , n represents an integer of 1 or more), a water-soluble polymer, and a vinylpyrrolidone-vinylcaprolactam copolymer as a main component. It is formed by applying and drying the coating liquid The heat-sensitive transfer recording medium is characterized in that the water-soluble polymer is polyvinyl alcohol and / or polyvinyl pyrrolidone.
The invention according to claim 2 is the thermal transfer recording medium according to claim 1 , wherein the silicon compound represented by the general formula Si (OR ¹ ) ₄ is tetraethoxysilane.
A third aspect of the present invention is the thermal transfer recording medium according to the first aspect , wherein the coating amount of the undercoat layer after drying is in the range of 0.10 to 0.30 g / m ^2. is there.

  According to the heat-sensitive transfer recording medium of the present invention, the transfer sensitivity at the time of high-speed printing is high, that is, high-density printing can be obtained without increasing the dye used in the dye layer, and even after storage at high temperature and high humidity. There is no abnormal transfer in printing, and a sufficiently satisfactory printed material with less so-called “shine” phenomenon can be obtained.

1 is a side sectional view of an embodiment of a thermal transfer recording medium of the present invention.

  Hereinafter, the thermal transfer recording medium of the present invention will be described in detail with reference to FIG. This is a structure in which a heat-resistant slipping layer 2 that imparts slidability with a thermal head is provided on one surface of the substrate 1, and an undercoat layer 3 and a dye layer 4 are sequentially formed on the other surface of the substrate 1.

  Since the base material 1 is required to have heat resistance and strength not to be softened and deformed by heat pressure in thermal transfer, for example, polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, acetate, polycarbonate, polysulfone, polyimide, polyvinyl alcohol, aromatic Synthetic resin films such as polyamide, aramid, and polystyrene, and paper such as condenser paper and paraffin paper can be used alone or in combination, but in particular, physical properties, workability, cost, etc. In view of the above, a polyethylene terephthalate film is preferable. In addition, the thickness is in the range of 2 to 50 μm in consideration of operability and workability, but in consideration of handling properties such as transfer suitability and workability, the thickness is about 2 to 9 μm. preferable.

  Moreover, in the base material 1, it is also possible to perform an adhesion treatment on the surface on which the heat resistant slipping layer 2 and / or the undercoat layer 3 is formed. As the adhesion treatment, known techniques such as corona treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, roughening treatment, plasma treatment, primer treatment, etc. can be applied, and these treatments are used in combination. You can also In the present invention, it is effective to improve the adhesion between the base material and the undercoat layer, and a primer-treated polyethylene terephthalate film is preferable in consideration of cost.

Next, the heat-resistant slipping layer 2 can be handled by a conventionally known layer. For example, a resin serving as a binder, a functional additive imparting releasability or slipperiness, a filler, a curing agent, a solvent, and the like are blended. And can be formed by coating and drying. The coating amount after drying of the heat resistant slipping layer is suitably about 0.1 to 2.0 g / m ² .

  As an example of the heat resistant slipping layer, the binder resin may be polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer, polyether resin, polybutadiene resin, acrylic polyol, polyurethane acrylate, polyester. Examples thereof include acrylate, polyether acrylate, epoxy acrylate, nitrocellulose resin, cellulose acetate resin, polyamide resin, polyimide resin, polyamideimide resin, and polycarbonate resin. Functional additives include natural waxes such as animal waxes and plant waxes, synthetic hydrocarbon waxes, aliphatic alcohols and acid waxes, fatty acid esters and glycerite waxes, synthetic ketone waxes, amine and amide waxes , Synthetic waxes such as chlorinated hydrocarbon wax and alpha-olefin wax, higher fatty acid esters such as butyl stearate and ethyl oleate, sodium stearate, zinc stearate, calcium stearate, potassium stearate, magnesium stearate, etc. Surfactants such as higher fatty acid metal salts, long chain alkyl phosphate esters, polyoxyalkylene alkyl aryl ether phosphate esters or phosphate esters such as polyoxyalkylene alkyl ether phosphate esters, etc. Rukoto can. As fillers, talc, silica, magnesium oxide, zinc oxide, calcium carbonate, magnesium carbonate, kaolin, clay, silicone particles, polyethylene resin particles, polypropylene resin particles, polystyrene resin particles, polymethyl methacrylate resin particles, polyurethane resin particles, etc. Can be mentioned. Examples of the curing agent include isocyanates such as tolylene diisocyanate, triphenylmethane triisocyanate, tetramethylxylene diisocyanate, and derivatives thereof, but the above are not particularly limited.

Next, the undercoat layer 3 includes, as an essential component of the present invention, a silicon compound represented by the general formula Si (OR ¹ ) ₄ and a hydrolyzate thereof, and a general formula (R ² Si (OR ³ ) ₃ ) _n. Wherein R ¹ and R ³ are CH ₃ , C ₂ H ₅ , or C ₂ H ₄ OCH ₃ , R ² is an organic functional group, and n is 1 or more. It can be formed by applying and drying a coating solution containing, as main components, a water-soluble polymer and a vinylpyrrolidone-vinylcaprolactam copolymer.

  Examples of water-soluble polymers include polyvinyl alcohol, polyvinyl pyrrolidone, starch, gelatin, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, sodium alginate and the like. Among them, polyvinyl alcohol or polyvinyl pyrrolidone is preferable and is an essential component of the undercoat layer in the present invention.

  The polyvinyl alcohol in the present invention is generally obtained by saponifying polyvinyl acetate, and so-called completely saponified polyvinyl alcohol in which only several percent of acetate groups remain from so-called partially saponified polyvinyl alcohol in which several tens percent of acetate groups remain. It includes up to saponified polyvinyl alcohol and is not particularly limited. Examples of the polyvinyl alcohol resin used for the undercoat layer include Kuraray Poval PVA-235 (manufactured by Kuraray Co., Ltd.), Kuraray Poval PVA-117 (manufactured by Kuraray Co., Ltd.), Kuraray Poval PVA-124 (manufactured by Kuraray Co., Ltd.), Gohsenol KH-20 ( Nippon Synthetic Chemical Co., Ltd.), Gohsenol N-300 (Nippon Synthetic Chemical Co., Ltd.) and other polyvinyl alcohols, and acetoacetylated polyvinyl alcohols that have acetoacetyl groups and are rich in reactivity. 320 (manufactured by Nippon Synthetic Chemical Co., Ltd.), water-based polyvinyl acetal ESREC KX series (manufactured by Sekisui Chemical Co., Ltd.), SRECK KW series (manufactured by Sekisui Chemical Co., Ltd.), etc., in which some alcohol groups of polyvinyl alcohol are acetal-modified.

  Examples of polyvinyl pyrrolidone include homopolymers of vinyl pyrrolidone such as N-vinyl-2-pyrrolidone and N-vinyl-4-pyrrolidone, and copolymers thereof. Furthermore, modified polyvinyl pyrrolidone resin and the like can be mentioned. The modified polyvinyl pyrrolidone resin is a copolymer of an N-vinyl pyrrolidone monomer and another monomer. The form of copolymerization is not particularly limited, such as random copolymerization, block copolymerization, and graft copolymerization. The N-vinyl pyrrolidone monomer mentioned above refers to N-vinyl pyrrolidone (N-vinyl-2-pyrrolidone, N-vinyl-4-pyrrolidone, etc.) and derivatives thereof. Examples thereof include those having a substituent on the pyrrolidone ring such as vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-3,3,5-trimethylpyrrolidone, N-vinyl-3-benzylpyrrolidone. .

  Examples of the monomer component copolymerized with the N-vinylpyrrolidone monomer include the following vinyl polymerizable monomers. For example, (meth) acrylic monomers such as (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, unsaturated carboxylic acids such as fumaric acid, maleic acid, itaconic acid, ethylene, Examples include propylene, vinyl chloride, vinyl acetate, vinyl alcohol, styrene, vinyl toluene, divinylbenzene, vinylidene chloride, ethylene tetrafluoride, and vinylidene fluoride.

  The vinylpyrrolidone-vinylcaprolactam copolymer is a copolymer of an N-vinylpyrrolidone monomer and a vinylcaprolactam which is a vinyl polymerizable monomer. The form of copolymerization is not limited to any of random copolymerization, block copolymerization, and graft copolymerization. Here, the N-vinyl pyrrolidone-based monomer refers to N-vinyl pyrrolidone (N-vinyl-2-pyrrolidone, N-vinyl-4-pyrrolidone, etc.) and derivatives thereof. Examples of those having a substituent on the pyrrolidone ring such as vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-3-benzylpyrrolidone, N-vinyl-3,3,5-trimethylpyrrolidone However, it is not particularly limited.

  The vinyl pyrrolidone-vinyl caprolactam copolymer is considered to have been compensated by the vinyl caprolactam component for the poor heat resistance and moisture resistance of the water-soluble polymer component and the vinyl pyrrolidone component. High, can prevent abnormal transfer in printing, and can exhibit the function of reducing the shine in the high density portion during high-speed printing. Here, in the vinylpyrrolidone-vinylcaprolactam copolymer, the polymerization ratio of vinylpyrrolidone and vinylcaprolactam is preferably (vinylpyrrolidone) / (vinylcaprolactam) = 8/2 to 2/8 in a molar ratio. In some cases, the above functions can be sufficiently exhibited.

The metal alkoxide represented by the general formula Si (OR ¹ ) ₄ is condensed after hydrolysis to form a chain or three-dimensional polymer. However, since the metal oxide is hard and cracks easily occur due to distortion due to volume reduction during condensation, it is very difficult to form a thin, transparent and uniform condensate film on the film. Therefore, by adding a polymer, flexibility can be imparted to the structure and cracks can be prevented to form a film. The metal alkoxide forms a complex at the molecular level with the water-soluble polymer, and the alkoxide and / or its hydrolyzate in the undercoat layer contributes to the improvement of transfer sensitivity at the time of high-speed printing, which is insufficient with the water-soluble polymer alone. I think that. However, the subbing layer consisting of a mixture of a metal alkoxide or its hydrolyzate and a water-soluble polymer having a hydroxyl group is composed of hydrogen bonds, so that the subbing layer swells with water during long-term storage under high temperature and high humidity. The deterioration of the adhesive tends to cause a decrease in adhesion.

In contrast, in the present invention, by adding the above-mentioned general formula _{^{(R 2 Si (OR 3)}} 3) a compound represented by _n, it is possible to prevent this swelling. In the general formula (R ² Si (OR ³ ) ₃ ) _n , the organic functional group (R ₂ ) is preferably a non-aqueous functional group such as vinyl, epoxy, methacryloxy, ureido, and isocyanate. The non-aqueous functional group is further improved in water resistance since the functional group is hydrophobic. General Formula (R ² Si (OR ³ ) ₃ ) When the compound represented by _n is a multimer, a trimer is preferable, and more preferably, the general formula (NCO-R ⁴ Si (OR ³ ) ₃ ) ₃ (wherein R ⁴ is (CH ₂ ) _n , n is 1 or more, preferably n is 1 to 5), 1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate . This is a condensate of 3-isocyanatoalkylalkoxysilane. This 1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate is known to exhibit the same performance as the reaction due to the polarity of the nurate part, although the isocyanurate part has no chemical reactivity. Yes.

In general, it is added to an adhesive or the like in the same manner as 3-isocyanate alkylalkoxysilane and is known as an adhesion improver. Therefore, by adding 1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate to Si (OR ¹ ) ₄ and a water-soluble polymer having a hydroxyl group, it is prevented from swelling due to water and is resistant to moisture. Can be improved.

  1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate may be produced by thermal condensation of 3-isocyanatepropylalkoxysilane, and may contain 3-isocyanatepropylalkoxysilane as a raw material. But there is no problem.

The general formula Si (OR ¹ ) ₄ is preferably such that R ¹ can be represented by CH ₃ , C ₂ H ₅ , C ₂ H ₄ OCH _3, etc., especially tetraethoxysilane Si (OC ₂ H ₅ ) ₄ is hydrolyzed. After decomposition, it is preferable because it is relatively stable in an aqueous solvent.
Here, (A) a silicon compound represented by the general formula Si (OR ¹ ) ₄ and / or a hydrolyzate thereof, and (B) a silicon represented by the general formula (R ² Si (OR ³ ) ₃ ) _n The compound and / or hydrolyzate thereof, (C) water-soluble polymer, and (D) vinylpyrrolidone-vinylcaprolactam copolymer are used in a mass ratio of (A) 10-20: (B) 1-2: (C) 1-4: (D) 1-4 is preferable.

The coating amount of the undercoat layer after drying is not generally limited, but is preferably in the range of 0.10 to 0.30 g / m ² . Is less than 0.10 g / m ^2, the deterioration during the dye layer stack, there is a possibility has problems insufficient transfer sensitivity during high speed printing, the adhesion to the substrate or a dye layer. On the other hand, if it exceeds 0.30 g / m ² , the sensitivity of the thermal transfer recording medium itself is affected, and the transfer sensitivity at the time of high-speed printing may be insufficient.

Next, the dye layer 4 can cope with a conventionally known one, for example, a dye layer forming coating solution is prepared by blending a heat transferable dye, a binder, a solvent, and the like, and formed by coating and drying. About 1.0 g / m ² is appropriate. Note that the dye layer can be composed of a single layer of one color, or a plurality of dye layers containing dyes having different hues can be repeatedly formed on the same surface of the same base material in the surface order.

  The heat transferable dye in the dye layer is not particularly limited as long as it is a dye that melts, diffuses, or sublimates and transfers due to heat. For example, the yellow component includes solvent yellow 56, 16, 30, 93, 33. , Disperse Yellow 201, 231, 33 and the like. Examples of the magenta component include C.I. I. Disperse thread 60, C.I. I. Disperse violet 26, C.I. I. Solvent Red 27, or C.I. I. Solvent Red 19 etc. can be mentioned. As the cyan component, C.I. I. Disperse Blue 354, C.I. I. Solvent Blue 63, C.I. I. Solvent Blue 36, or C.I. I. Disperse Blue 24 and the like. As a black ink dye, it is common to perform color matching by combining the above dyes.

  As the binder for the dye layer, any conventionally known resin binder can be used, and is not particularly limited. However, cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, and cellulose acetate, and polyvinyl Examples thereof include vinyl resins such as alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, and polyacrylamide, polyester resins, styrene-acrylonitrile copolymer resins, and phenoxy resins.

  Here, the ratio of the dye and the binder in the dye layer is preferably dye / binder = 10/100 to 300/100. This is because when the dye / binder ratio is less than 10/100, the amount of dye is too small and the color development sensitivity is insufficient, and a good thermal transfer image cannot be obtained. This is because the solubility of the dye with respect to the ink is extremely lowered, so that when it becomes a thermal transfer recording medium, the storage stability is deteriorated and the dye is likely to be precipitated. Further, known additives such as isocyanate compounds, silane coupling agents, dispersants, viscosity modifiers, stabilizers and the like can be used in the dye layer or the dye layer forming coating solution as long as the performance is not impaired.

  The image receiving paper used as the transfer medium used in the present invention will be described.

  As the image receiving paper substrate, papers mainly composed of cellulose pulp can be used. Examples of paper include coated paper, art paper, high-quality paper (acidic paper, neutral paper), medium-quality paper, and glassine paper.

  Furthermore, it is preferable to form a heat insulating layer containing hollow particles and an adhesive component on the image receiving paper substrate. Thermal transfer printing is performed by heating from a thermal head, and it is required that the thermal head and the image receiving paper substrate have good adhesion. Since the image receiving paper base material having the heat insulating layer has cushioning properties, adhesion with the thermal head is improved, and a more uniform image can be obtained at the time of printing. As a material for forming the walls of the hollow particles used in the heat insulating layer, acrylonitrile, vinylidene chloride, a polymer of styrene acrylate, and the like are preferably used. Examples of the method for producing the hollow particles include a method in which a foaming agent such as butane gas is encapsulated in the resin particles and foamed by heating, an emulsion polymerization method, and the like. As a method of heating and foaming, when using pre-foamed hollow particles in which hollow particles are pre-foamed by overheating, and after forming a heat insulating layer containing unfoamed particles by coating, etc., heat treatment such as a drying step May form a hollow structure in the heat insulating layer. From the viewpoint of easily controlling the hollow ratio and particle diameter of the hollow particles, it is generally preferable to use the already-expanded particles.

  As the dyeing resin used for the image receiving layer formed on the image receiving paper substrate or the heat insulating layer, a thermoplastic resin having high affinity for dye and good dye dyeing property is used. Examples of the resin include vinyl chloride resin, urethane resin, polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, polystyrene resin, polyacrylate resin, acrylic resin, cellulose resin, and polyamide resin. A thermoplastic resin such as a copolymer resin of a vinyl compound monomer and a monomer having a benzotriazole skeleton and / or a benzophenone skeleton, and these thermoplastic resins may be used alone or in combination of two or more. You may use together. Further, the dyeing resin is more preferably composed of a water-soluble or water-dispersed so-called aqueous system from the viewpoint of environmental load.

  In thermal transfer printing, there is a process in which the image receiving layer on the image receiving paper substrate and the dye layer of the ink ribbon are overlaid and heated with a thermal head, and then the ink ribbon is peeled off from the image receiving layer. And releasability is also required. For this reason, it is preferable to add a release agent to the image receiving layer for the purpose of preventing fusion with the ink ribbon and improving printing runnability. Examples of the release agent to be added include silicone oil, polysiloxane graft acrylic resin, waxes, and fluorine compounds.

  The image receiving layer is preferably added with a crosslinking agent to improve heat resistance. As a crosslinking agent, a carbodiimide compound, an isocyanate compound, an oxazoline compound, and an organic titanium chelate compound are preferable. Among these cross-linking agents, carbodiimide-based cross-linking agents are preferable because they are highly effective in improving heat resistance, are less likely to cause running problems such as ribbon fusion during printing, and are stable in aqueous paints. . The addition amount of the carbodiimide crosslinking agent is preferably 1 to 30 parts, more preferably 3 to 25 parts, with respect to 100 parts of the resin contained in the image receiving layer. If it is less than 1 part, sufficient crosslinking effect cannot be obtained, and printing running failure may occur. If it exceeds 30 parts, the curing property of the resin may inhibit the density of the printed image.

The coating amount of the image-receiving layer is preferably from 0.5 to 5.0 g / ^{m 2,} more preferably from 0.5 to 4.0 g / ^{m 2.} If it is less than 0.5 g / m ² , the light resistance of the image may be inferior. If it exceeds 5.0 g / m ² , the dye may diffuse in the image receiving layer, and image bleeding may occur.

  The materials and methods used in the examples and comparative examples of the present invention are shown below. In the text, “part” is based on mass unless otherwise specified.

<Preparation of image receiving paper to be transferred>
Art paper having a basis weight of 180 g / m ² was used as the image receiving paper substrate.

<Formation of heat insulation layer>
The following composition heat insulating layer coating solution is applied on the image receiving paper substrate by a gravure coating method so that the coating amount after drying becomes 10 g / m ² , and then aged in a 40 ° C. environment for one week. Thus, an image receiving paper with a heat insulating layer was obtained.

<Insulation layer coating solution>
Mainly composed of acrylonitrile and methacrylonitrile
45 parts of already foamed hollow particles made of a copolymer (average particle size 3.2 μm, volume hollowness 85%)
Polyvinyl alcohol 10 parts Vinyl chloride vinyl acetate copolymer resin dispersion 45 parts (vinyl chloride / vinyl acetate = 7/3, T _g 64 ° C.)
200 parts of water

<Formation of image receiving layer>
By applying and drying the following composition image-receiving layer coating solution on the heat insulation layer by a gravure coating method so that the coating amount after drying becomes 4 g / m ^2, and then aging in a 40 ° C. environment for one week. An image receiving layer was obtained.

<Image-receiving layer coating solution>
97 parts of urethane resin (glass transition temperature: -20 ° C)
Associative urethane thickener 1 part sulfonic acid surfactant 2 parts water 200 parts

<Preparation of substrate with heat-resistant slip layer>
As a base material, a polyethylene terephthalate film with a single-sided easy adhesion treatment of 4.5 μm is used, and a heat resistant slipping layer coating solution having the following composition is applied to the non-easy adhesion treatment surface by a gravure coating method so that the coating amount after drying is 1 After coating and drying so as to be 0.0 g / m ² , the substrate with a heat-resistant slipping layer was obtained by aging in a 40 ° C. environment for 1 week.
<Heat resistant slipping layer coating solution>
Acrylic polyol resin 12.5 parts Polyoxyalkylene alkyl ether / phosphate ester 2.5 parts talc 6.0 parts 2,6-tolylene diisocyanate prepolymer 4.0 parts toluene 50.0 parts methyl ethyl ketone 20.0 parts ethyl acetate 5.0 parts

<Preparation of undercoat layer coating solution>
A: 17.3 parts of tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ) and 10.0 parts of methanol were added 72.7 parts of hydrochloric acid (0.1N), and the mixture was stirred for 30 minutes for hydrolysis. solution
B: 2.0 parts of polyvinyl alcohol and vinylpyrrolidone-vinylcaprolactam copolymer (copolymerization ratio (molar ratio): 1/1) 3.0 parts in a mixed solution of 90.0 parts of water and 5.0 parts of methanol Dissolved solution C: 2.0 parts of polyvinylpyrrolidone and vinylpyrrolidone-vinylcaprolactam copolymer [copolymerization ratio (molar ratio): 1/1 in a mixed solution of 90.0 parts of water and 5.0 parts of methanol Solution D in which 3.0 parts were dissolved: 1.5 parts of polyvinyl alcohol, 1.5 parts of polyvinylpyrrolidone and vinylpyrrolidone-vinylcaprolactam copolymer in a mixed solution of 90.0 parts of water and 5.0 parts of methanol [Copolymerization ratio (molar ratio): 1/1] Dissolved solution in which 2.0 parts were dissolved E: Vinylpyrrolidone-vinylcaprolactam copolymer [copolymerized in a mixed solution of 90.0 parts of water and 5.0 parts of methanol polymerization (Molar ratio): 1/1] Solution F in which 5.0 parts are dissolved: Solution G in which 5.0 parts of polyvinyl alcohol is dissolved in a mixture of 90.0 parts of water and 5.0 parts of methanol: Dissolved solution H obtained by dissolving 5.0 parts of polyvinylpyrrolidone in a mixed solution of 90.0 parts of water and 5.0 parts of methanol: 2.5 parts of polyvinyl alcohol in a mixed solution of 90.0 parts of water and 5.0 parts of methanol Solution I in which 2.5 parts of polyvinylpyrrolidone was dissolved: 45.0 parts of water, 45.0 parts of IPA, and 10.0 parts of 1,3,5-tris (3-methoxysilylpropyl) isocyanurate were mixed. Mixture J stirred for 5 minutes: mixed with 23.4 parts of water and 47.9 parts of IPA, 0.7 parts of vinylpyrrolidone-vinyl acetate copolymer [copolymerization ratio (molar ratio): 1/1] and alumina sol 28 0.0 part mixed and stirred for 30 minutes

Example 1
A gravure coating solution prepared by mixing the undercoat layer coating solution prepared above on the surface of the substrate with a heat-resistant slipping layer with a mass ratio of A / B / I = 70/20/10 and stirring for 30 minutes. The undercoat layer was formed by coating and drying by a coating method such that the coating amount after drying was 0.2 g / m ² . Subsequently, a dye layer coating liquid having the following composition is applied onto the undercoat layer by a gravure coating method so that the coating amount after drying is 0.7 g / m ² , and the dye layer is then dried. The thermal transfer recording medium of Example 1 was obtained.
<Dye layer coating solution>
C. I. Solvent Blue 63 6.0 parts Polyvinyl acetal resin 4.0 parts Toluene 45.0 parts Methyl ethyl ketone 45.0 parts

(Example 2)
The thermal transfer recording medium produced in Example 1 was the same as in Example 1 except that the undercoat layer coating liquid prepared as described above was mixed at a mass ratio of A / C / I = 70/20/10. Similarly, a thermal recording transfer medium of Example 2 was obtained.

(Example 3)
The thermal transfer recording medium produced in Example 1 was the same as Example 1 except that the undercoat layer coating solution prepared above was mixed at a mass ratio of A / D / I = 70/20/10. Similarly, a thermal recording transfer medium of Example 3 was obtained.

Example 4
In the heat-sensitive transfer recording medium produced in Example 3, the example was applied in the same manner as in Example 3 except that the undercoat layer was applied and dried so that the coating amount after drying was 0.05 g / m ^2. No. 4 thermal recording transfer medium was obtained.

(Example 5)
In the heat-sensitive transfer recording medium produced in Example 3, the example was applied in the same manner as in Example 3 except that the undercoat layer was applied and dried so that the coating amount after drying was 0.35 g / m ^2. No. 5 thermal recording transfer medium was obtained.

(Comparative Example 1)
After forming the undercoat layer on the easy-adhesion treated surface of the substrate with a heat-resistant slipping layer, the same dye layer coating solution as in Example 1 is dried on the easy-adhesive treated surface by a gravure coating method. The dye layer was formed by coating and drying so that the coating amount was 0.7 g / m ² , and the thermal transfer recording medium of Comparative Example 1 was obtained.

(Comparative Example 2)
The thermal transfer recording medium produced in Example 1 was the same as in Example 1 except that the undercoat layer coating liquid prepared above was mixed at a mass ratio of A / E / I = 70/20/10. Similarly, a thermal recording transfer medium of Comparative Example 2 was obtained.

(Comparative Example 3)
In the heat-sensitive transfer recording medium produced in Example 1, the same procedure as in Example 1 was conducted except that the undercoat layer coating liquid prepared as described above was mixed at A / F / I = 70/20/10. Thus, a thermal recording transfer medium of Comparative Example 3 was obtained.

(Comparative Example 4)
The thermal transfer recording medium produced in Example 1 is the same as in Example 1 except that the undercoat layer coating solution prepared as described above was mixed at a mass ratio of A / G / I = 70/20/10. Similarly, a thermal recording transfer medium of Comparative Example 4 was obtained.

(Comparative Example 5)
The thermal transfer recording medium produced in Example 1 was the same as in Example 1 except that the undercoat layer coating solution prepared above was mixed at a mass ratio of A / H / I = 70/20/10. Similarly, a thermal recording transfer medium of Comparative Example 5 was obtained.

(Comparative Example 6)
In the heat-sensitive transfer recording medium produced in Example 1, the undercoat layer was prepared in the same manner as in Example 1 except that the undercoat layer coating solution prepared above was mixed at a mass ratio of A / D = 70/30. A thermal recording transfer medium of Comparative Example 6 was obtained.

(Comparative Example 7)
In the heat-sensitive transfer recording medium produced in Example 1, the heat-sensitive recording transfer medium of Comparative Example 7 was prepared in the same manner as in Example 1 except that the undercoat layer coating liquid having the undercoat layer prepared above was changed to D only. Obtained.

(Comparative Example 8)
In the heat-sensitive transfer recording medium produced in Example 1, the heat-sensitive recording transfer medium of Comparative Example 8 was prepared in the same manner as in Example 1 except that the undercoat layer coating liquid having the undercoat layer prepared above was changed to J only. Obtained.

<Print evaluation>
Regarding the thermal transfer recording media of Examples 1 to 5 and Comparative Examples 1 to 8, the thermal transfer recording media stored at room temperature, and after being stored in an environment of 50 ° C. and 80% RH for 72 hours, further 24 at room temperature. Table 1 shows the results of performing solid printing with a thermal simulator using a thermal transfer recording medium and a transfer medium that have been stored for a long time, the presence or absence of abnormal transfer, the evaluation of shine, and the measurement of the maximum reflection density. Note that the maximum reflection density is a value obtained by measuring a printed portion where no shine is confirmed with X-Rite 528.

<Printing conditions>
Printing environment: 23 ° C, 50% RH
Applied voltage: 29V
Line cycle: 0.7msec
Print density: main scanning 300 dpi sub-scanning 300 dpi

<Evaluation criteria>
The abnormal transcription was evaluated according to the following criteria.
○: Abnormal transfer to the transfer object is not observed Δ: Abnormal transfer to the transfer object is very slight ×: Abnormal transfer to the transfer object is observed on the entire surface The following criteria were used.
◯: No shine is recognized Δ: Tekali is partially recognized
X: Tekari is clearly recognized.

  In the above evaluation method / evaluation standard, the practically allowable lower limit values are abnormal transfer: Δ, shine: Δ, and maximum reflection density: 2.35.

  From the results shown in Table 1, for abnormal transfer, there was no problem with abnormal transfer during storage at room temperature, and there was no problem. However, in the evaluation after the high-temperature / high-humidity storage test, 1,3,5-Tris ( The thermal transfer recording medium lacking 3-methoxysilylpropyl) isocyanurate and the thermal transfer recording medium lacking tetraethoxysilane and 1,3,5-tris (3-methoxysilylpropyl) isocyanurate of Comparative Example 7 were printed. Abnormal transfer occurred on the entire surface of the material, and it was confirmed that the adhesion of the dye layer was clearly deteriorated during storage at high temperature and high humidity.

  As for shine, in Comparative Examples 3 to 5 where no vinylpyrrolidone-vinylcaprolactam copolymer was used, shine was clearly recognized, but no shine was observed in the thermal transfer recording media of Examples 1 to 5, or The effect of using the vinylpyrrolidone-vinylcaprolactam copolymer was confirmed to the extent that it was partially recognized. In addition, compared with the thermal transfer recording medium of Comparative Example 1 in which no undercoat layer is provided, the thermal transfer recording media of Examples 1 to 5 have a reflection density exceeding 2.35, and the transfer sensitivity is sufficiently high. I understood it. Further, the thermal transfer recording media of Example 2, Comparative Example 2 and Comparative Example 4 lacking polyvinyl alcohol in the undercoat layer tended to have little effect of increasing the sensitivity. Evaluation was also made on the shine and reflection density after storage at high temperature and high humidity, but it was found that there was no significant change in performance and there was no practical problem.

It can be seen that the heat-sensitive transfer recording medium of Example 4 has somewhat lower adhesion after storage at high temperature and high humidity because the coating amount of the undercoat layer is less than 0.10 g / m ² . In addition, it can be seen that the thermal transfer recording medium of Example 5 has a tendency to deteriorate transfer sensitivity and shine due to the coating amount of the undercoat layer exceeding 0.30 g / m ^2. I found that there was no problem.

  Further, in the thermal transfer recording medium of Comparative Example 8, as a result of providing the undercoat layer with a mixture of vinyl pyrrolidone-vinyl acetate copolymer and alumina sol, abnormal transfer, shine, and maximum reflection density are generally practical when stored at room temperature. Although there is no problem, it has been found that there is a problem with the shine of high temperature and high humidity storage products.

  The thermal transfer recording medium obtained according to the present invention is an ink ribbon used in a sublimation transfer type printer, and in addition to the high speed and high functionality of the printer, various images can be easily formed in full color. Self-prints, cards such as identification cards, amusement output, etc. can be widely used.

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Heat-resistant slipping layer, 3 ... Undercoat layer, 4 ... Dye layer

Claims (3)

In a thermal transfer recording medium in which a heat-resistant slipping layer is provided on one surface of a substrate, and an undercoat layer and a dye layer are sequentially formed on the other surface of the substrate, the undercoat layer has a general formula Si (OR ¹ 3) a silicon compound represented by ₄ and / or a hydrolyzate thereof, and a trimer 1,3,5-tris (3-tris represented by the general formula (NCO-R ⁴ Si (OR ³ ) ₃ ) ₃ ) ( Alkoxysilylalkyl) isocyanurate and / or a hydrolyzate thereof (wherein R ¹ and R ³ are CH ₃ , C ₂ H ₅ , or C ₂ H ₄ OCH ₃ , R ⁴ is (CH ₂ ) _n , n is 1 And a coating solution containing a water-soluble polymer and a vinylpyrrolidone-vinylcaprolactam copolymer as main components, and dried to form polyvinyl alcohol and / or polyvinylpyrrolidone. In A thermal transfer recording medium characterized by the above. Formula Si (OR ¹⁾ a silicon compound represented by the ₄ heat-sensitive transfer recording medium of claim 1, wherein the tetraethoxysilane. Coating amount after drying of the undercoat layer is a thermal transfer recording medium according to claim 1, wherein in the range of 0.10~0.30g / ^{m 2.}

Images