JP2007261236A - Thermal transfer recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-grade thermal transfer recording material which can obtain a high printing density, which does not cause unevenness in printing, which brings about little difference in gloss between a print area and a non-print area, and which does not cause a blister in a high-density print area. <P>SOLUTION: This thermal transfer recording material is characterized in that: a porous intermediate layer, which contains a resin binder and inorganic particulates with a mean secondary particle diameter of 500 nm or less, is provided on a substrate; an ink absorbing layer, which is composed mainly of a polyester resin, is provided on the intermediate layer; the inorganic particulate is one kind selected from among vapor-phase silica, hydrated alumina and wet silica, or a mixture thereof; the resin binder is modified polyvinyl alcohol with a keto group; and a cross-linking agent layer for cross-linking the modified polyvinyl alcohol with the keto group is provided adjacently to the intermediate layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermal transfer recording material that forms an image by transferring and fixing ink from a donor sheet or film by a heating means, and particularly relates to a photographic quality thermal transfer recording material having a high print density and excellent image quality.

  In recent years, digitalization of image information has progressed, and various printer devices that have been used as output devices for characters and lines have been required to have a quality corresponding to image output. The thermal transfer recording method is a method in which a donor sheet or a donor film, which is uniformly coated with ink on one side, is in contact with a recording material or disposed in the immediate vicinity, and the ink on the donor sheet is formed by a heating element typified by a thermal head. Is a recording method in which the ink is melted and ink is transferred to the recording material. This is a recording method that has been used as an output device for color since it can handle colors by using an inexpensive thermal head with excellent durability and maintainability of the element and preparing a donor sheet of the required color. .

  In such a recording method, the characteristics of the recording material are important when outputting images and photographs that require high resolution and high image quality. That is, for image output, a high-resolution thermal head with a small element area per element is used in order to obtain smoothness of the image and high gradation. In such a head, since the amount of heat generated per element is small, the effect of heat dissipation is large in the recording material, and the thermal energy necessary for the transfer of ink is maintained, so that heat insulation is important in the recording material. . That is, if a recording material having low heat insulation and heat is easily dissipated, there is a problem that ink transfer is not sufficient and a desired image density cannot be obtained.

  As the thermal transfer recording material, another important characteristic is smoothness of the image receiving surface. In other words, when the smoothness of the image receiving surface is low, a portion where the distance between the donor sheet and the image receiving surface is different occurs.If the amount of transferred ink varies depending on the distance, it appears as image unevenness, and as an image output application, It becomes inappropriate.

  As means for improving the smoothness, for example, as in Patent Document 1, a laminated substrate of paper or synthetic paper is described. However, with such a configuration, heat insulation of the image receiving layer cannot be expected, and a sufficient image density cannot be obtained.

  For example, as disclosed in Patent Document 2 and Patent Document 3, paper or foam film, and a configuration for bonding them to paper are disclosed. However, in such a configuration, since there is no liquid or gas permeability or absorptivity, the solvent component of the transferred ink remains on the surface, and an unnatural gloss difference appears between the image area and the non-image, so that The texture is poor. Further, as disclosed in Patent Document 4, for example, a method for improving heat insulation by providing a heat insulating intermediate layer made of foamed resin below the image receiving layer is disclosed. Even in such a method, since the foamed resin layer has a remarkably low liquid or gas permeability and absorbability as a coating layer, an unnatural difference in gloss between the image portion and the non-image ink is expressed, and the ink and the image receiving layer are It was difficult to generate a blister due to the vaporization of the solvent component by heat and to obtain a high-quality image.

  Patent Document 5 discloses a configuration in which a porous layer is formed of an inorganic fine particle and a water-soluble resin as an intermediate layer, and a reactive monomer or oligomer is applied to the upper layer. According to such a configuration, it is possible to suppress the generation of blisters due to the solvent component of the transferred ink. However, when a monomer or oligomer having a low molecular weight is applied to the upper layer, the component penetrates into the porous layer. In order to close the gap, the absorbability and heat insulation of the solvent component are lowered. In addition, unreacted monomers and oligomers remain, obstructing the transferability of the ink and causing a problem that the printing density is lowered.

In addition to smoothness, the ink receiving layer is important for the transferability and fixability of the transferred ink. In this respect, the material component of the ink receiving layer is the dominant factor. As a material component constituting the ink receiving layer, a polyester resin is preferably used as disclosed in Patent Document 6, for example. However, only by optimizing the raw materials such as the acid component and polyhydric alcohol component constituting the polyester resin, the physical properties such as the glass transition point, the molecular weight, the elastic modulus, etc. In an output device using a high-resolution thermal head having a small area per element, a sufficient print density cannot be obtained at present. Thus, it has been difficult for conventional thermal transfer recording materials to meet high-definition images and satisfy high-quality images and print density.
Japanese Examined Patent Publication No. 6-84119 Japanese Patent Publication No. 8-32487 Japanese Patent No. 2726040 JP 2001-39043 A Japanese Patent Laid-Open No. 9-22139 JP 2003-89276 A

  The object of the present invention is to provide a high print density by providing an intermediate layer, there is no occurrence of uneven printing, there is little difference in gloss between the printed part and the non-printed part, and there is no blister in the high density printed part. Is to provide a thermal transfer recording material.

The above object of the present invention has been basically achieved by the following invention.
(1) A porous intermediate layer containing inorganic fine particles having an average secondary particle diameter of 500 nm or less and a resin binder is provided on a support, and an ink receiving layer mainly composed of a polyester-based resin is provided on the intermediate layer. A thermal transfer recording material provided.
(2) The thermal transfer recording material according to (1), wherein the inorganic fine particles are one selected from gas phase method silica, alumina hydrate, and wet method silica, or a mixture thereof.
(3) The resin binder is a modified polyvinyl alcohol having a keto group, and a crosslinking agent layer for crosslinking the modified polyvinyl alcohol having a keto group is provided adjacent to the intermediate layer (1) or (2) The thermal transfer recording material as described.

  According to the present invention, a thermal transfer recording material that can achieve high print density, no density unevenness, little gloss difference between printed and non-printed parts, and satisfies the quality required for photographs without printed blisters. Can be provided.

  In the present invention, the ink-receiving layer preferably contains a polyester resin as a main component. Polyester resins consist of polycarboxylic acid components such as terephthalic acid, isophthalic acid, maleic acid, fumaric acid, phthalic acid, adipic acid, sebacic acid, azelaic acid, abietic acid, succinic acid, trimellitic acid and pyromellitic acid (these The carboxylic acid component may be substituted with a sulfonic acid group or the like) and ethylene glycol, diethylene glycol, propylene glycol, bisphenol A, diether derivatives of bisphenol A (for example, ethylene oxide 2 adduct of bisphenol A, bisphenol A) Propylene oxide 2 adducts, etc.), bisphenol S, 2-ethylcyclohexanedimethanol, neopentyl glycol, cyclohexanedimethanol, glycerin, and other polyalcohol components.

  Specific examples of the polyester resin include JP-A-59-101395, JP-A-63-7971, JP-A-63-7972, JP-A-63-7973, JP-A-60-294862. Can be mentioned. Examples of commercially available emulsion-type products include Toyobo's Bironal MD-1100, Bironal MD-1200, Bironal MD-1220, Bironal MD-1480, and Bironal MD-1985. Examples of solvent-soluble products include Byron 290, Byron 200, Byron 280, Byron 300, Byron 103, Byron GK-140, Byron GK-130, Toyobo made by Toyobo, Tufton NE-382, Tufton U-5, ATR-2009, ATR-2010, Elitel UE3500, UE3210, XA-8153 manufactured by Unitika, Polyester TP-220, R-188 manufactured by Nippon Synthetic Chemical, and the like can be mentioned. In particular, emulsion-type products can be preferably used because they have little penetration into the porous intermediate layer.

In the present invention, the main component of the polyester resin used in the ink receiving layer is to use it in a mass ratio of 70 to 100%. Components other than the polyester resin that can be used in the ink receiving layer include acrylic resins, styrene acrylic copolymer resins, ethylene vinyl acetate resins, urethane resins, urea resins, nylon resins, SBR, NBR and other solvent-soluble resins and emulsions, Various additives such as waxes such as polyethylene wax, fluorescent brighteners, and surfactants can be appropriately added. Moreover, it is preferable that the application quantity of the polyester resin used for an ink receiving layer is the range of 0.1-10 g / m < ² >.

  In the present invention, the intermediate layer is composed mainly of inorganic fine particles having an average secondary particle diameter of 500 nm or less and a resin binder. In the coating layer having such a structure, fine voids are formed between the particles, and the void ratio is large, so that the coating layer has heat insulating properties. Further, such voids absorb the solvent component of the transferred ink, fix the ink, and at the same time, obtain a natural and high-quality image with no gloss difference from the non-image area without imparting excessive gloss. be able to. On the other hand, when the average secondary particle diameter exceeds 500 nm, it becomes impossible to secure an effective void volume as an intermediate layer, and the printing density is lowered. Further, the gloss of the image receiving layer is lowered, so that the gloss required for a photograph cannot be obtained, the smoothness is insufficient, and ink density unevenness occurs.

The inorganic fine particles used in the present invention are preferably gas phase method silica, alumina hydrate, wet method silica, or a mixture thereof. According to such inorganic fine particles, an intermediate layer having a heat insulation property with a high void ratio can be obtained, and a desired ink transfer amount can be obtained in the image receiving layer. The coating amount of inorganic fine particles used for the intermediate layer is preferably in the range of ^{2 to} 35 g / m ² .

  The wet process silica used in the present invention is further classified into precipitation process silica, gel process silica, and sol process silica according to the production method. Precipitated silica is produced by reacting sodium silicate and sulfuric acid under alkaline conditions, and the silica particles that have grown are agglomerated and settled, and are then commercialized through filtration, water washing, drying, pulverization and classification. Precipitated silica is commercially available, for example, from Tosoh Silica Co., Ltd. as a nip seal and from Tokuyama Co., Ltd. as a Toxeal. Gel silica is produced by reacting sodium silicate and sulfuric acid under acidic conditions. During aging, the microparticles dissolve and reprecipitate so as to bind the other primary particles, so that the distinct primary particles disappear and form relatively hard aggregated particles having an internal void structure. For example, it is commercially available as nip gel from Tosoh Silica Co., Ltd., and as syloid and silo jet from Grace Japan Co., Ltd. The sol method silica is also called colloidal silica, and is obtained by heating and aging a silica sol obtained through metathesis of sodium silicate acid or the like through an ion exchange resin layer. For example, it is commercially available as Snowtex from Nissan Chemical Industries, Ltd. Yes.

  Vapor phase silica is also called a dry method as opposed to a wet method, and is generally made by a flame hydrolysis method. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known, but silanes such as methyltrichlorosilane and trichlorosilane can be used alone or silicon tetrachloride instead of silicon tetrachloride. Can be used in a mixed state. Vapor phase silica is commercially available as Aerosil from Nippon Aerosil Co., Ltd. and QS type from Tokuyama Co., Ltd.

  In the present invention, the vapor phase silica pulverized to an average secondary particle size of 500 nm or less is preferably dispersed in the presence of a cationic compound. As a dispersion method, gas phase method silica and a dispersion medium are premixed by ordinary propeller stirring, turbine type stirring, homomixer type stirring, etc., and then a media mill such as a ball mill, a bead mill, a sand grinder, a high pressure homogenizer, an ultrahigh pressure, etc. It is preferable to perform dispersion using a pressure disperser such as a homogenizer, an ultrasonic disperser, a thin film swirl disperser, or the like. The average secondary particle diameter in the present invention can be determined by photography using a transmission electron microscope. For simplicity, a laser scattering particle size distribution meter (for example, LA910, manufactured by Horiba, Ltd.) is used. Thus, it can be measured as the number median diameter.

  In the present invention, wet process silica pulverized to an average secondary particle diameter of 500 nm or less can also be preferably used. As the wet method silica used here, precipitation method silica or gel method silica is preferable, and precipitation method silica is particularly preferable. The wet process silica particles used in the present invention are preferably wet process silica particles having an average primary particle diameter of 50 nm or less, preferably 3 to 40 nm, and an average aggregate particle diameter of 5 to 50 μm.

  Since the wet process silica produced by a normal method has an average aggregate particle diameter of 1 μm or more, it is used after being finely pulverized. As a pulverization method, a wet dispersion method in which silica dispersed in an aqueous medium is mechanically pulverized can be preferably used. At this time, the increase in the initial viscosity of the dispersion is suppressed, high concentration dispersion is possible, and the pulverization / dispersion efficiency is increased so that it can be pulverized into fine particles. Therefore, precipitated silica having an average aggregate particle diameter of 5 μm or more is used. It is preferable to do.

  A specific method for obtaining wet process silica fine particles having an average secondary particle diameter of 500 nm or less in the present invention will be described. First, silica particles and a cationic compound are mixed in a dispersion medium mainly composed of water, and at least one dispersion device such as a sawtooth blade type dispersion machine, a propeller blade type dispersion machine, or a rotor stator type dispersion machine is used. Used to obtain a preliminary dispersion. If necessary, an appropriate low boiling point solvent or the like may be added to the aqueous dispersion medium. The higher the solid content concentration of the silica pre-dispersion liquid, the more preferable, but when the concentration is too high, it becomes impossible to disperse, so the preferable range is 15 to 40% by mass, and more preferably 20 to 35% by mass. Next, the silica particles are pulverized by applying the silica pre-dispersion to mechanical means having a stronger shearing force to obtain a wet process silica fine particle dispersion having an average secondary particle size of 500 nm or less. As the mechanical means, a known method can be adopted, for example, a media mill such as a ball mill, a bead mill, a sand grinder, a high pressure homogenizer, a pressure disperser such as an ultra high pressure homogenizer, an ultrasonic disperser, a thin film swirl disperser, etc. Can be used.

  As the cationic compound used for the dispersion of the gas phase method silica and the wet method silica, a cationic polymer can be preferably used. As the cationic polymer, polyethyleneimine, polydiallylamine, polyallylamine, alkylamine polymer, JP-A-59-20696, JP-A-59-33176, JP-A-59-33177, JP-A-59-155088, Sho 60-11389, Sho 60-49990, Sho 60-83882, Sho 60-109894, Sho 62-198493, Sho 63-49478, Sho 63-115780, Shosho 63-280681, No. 1-40371, No. 6-234268, No. 7-125411, No. 10-193976, etc. The polymer having is preferably used. In particular, diallylamine derivatives are preferably used as the cationic polymer. In terms of dispersibility and dispersion viscosity, the weight average molecular weight of these cationic polymers is preferably about 2,000 to 100,000, and particularly preferably about 2,000 to 30,000.

The alumina hydrate used in the present invention is represented by a constitutive formula of Al ₂ O ₃ .nH ₂ O (n = 1 to 3). The case where n is 1 represents an alumina hydrate having a boehmite structure, and the case where n is greater than 1 and less than 3 represents an alumina hydrate having a pseudo boehmite structure. The alumina hydrate is generally obtained by a known production method such as hydrolysis of an aluminum alkoxide such as aluminum isopropoxide, neutralization of an aluminum salt with an alkali, hydrolysis of an aluminate. The average secondary particle diameter of the alumina hydrate used in the present invention is 500 nm or less.

  The above-mentioned alumina hydrate used in the present invention is used in the form of a dispersion dispersed with a known dispersant such as acetic acid, lactic acid, formic acid, nitric acid and the like.

  Two or more kinds of inorganic fine particles may be used in combination from the inorganic fine particles described above. For example, combined use of finely pulverized wet method silica and vapor phase method silica, combined use of finely pulverized wet method silica and alumina hydrate, and combined use of vapor phase method silica and alumina hydrate. The ratio in the case of this combined use is not particularly limited.

  In the intermediate layer of the present invention, the content of inorganic fine particles having an average secondary particle diameter of 500 nm or less is preferably 50% by mass or more, more preferably 60% by mass or more, based on the total solid content of the intermediate layer. The range of 65-90 mass% is especially preferable. Thus, the intermediate layer having a high content ratio of inorganic fine particles constitutes a porous intermediate layer having a high porosity and a high heat insulating property. The porosity can be represented by the volume fraction of air contained in the coating layer by the volume fraction = (1−true specific gravity of the constituent / apparent specific gravity of the coating layer). A preferred range for the volume fraction of air that provides sufficient heat insulation is in the range of 0.2 to 0.7.

  In the present invention, as the binder constituting the intermediate layer and the cross-linking agent layer, various known binders can be used, and a hydrophilic binder that is highly transparent and can provide higher ink permeability is preferably used. In using the hydrophilic binder, it is important that the hydrophilic binder does not swell during the initial permeation of the ink and block the gap. From this viewpoint, a hydrophilic binder having a low swelling property at a relatively near room temperature is preferable. Used. Preferred hydrophilic binders are fully or partially saponified polyvinyl alcohol and cationic modified polyvinyl alcohol. The coating amount of the binder used for the intermediate layer is preferably used in the range of 4 to 45% with respect to the inorganic fine particles.

  Examples of the cation-modified polyvinyl alcohol include polyvinyl alcohol having a primary to tertiary amino group or a quaternary ammonium group in the main chain or side chain of polyvinyl alcohol as described in JP-A-61-110483. It is.

  In the present invention, if necessary, a hardening agent can be used together with the above hydrophilic binder constituting the ink receiving layer. Specific examples of the hardener include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedione, bis (2-chloroethylurea) -2-hydroxy-4,6-dichloro-1 , 3,5 triazine, a compound having a reactive halogen as described in US Pat. No. 3,288,775, divinyl sulfone, a compound having a reactive olefin as described in US Pat. No. 3,635,718, N-methylol compounds as described in Japanese Patent No. 2,732,316, isocyanates as described in US Pat. No. 3,103,437, US Pat. Nos. 3,017,280 and 2,983,611 described Aziridines such as carbodiimide compounds as described in US Pat. No. 3,100,704, Epoxy compounds as described in No. 3,091,537, halogen carboxaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane, chromium alum, zirconium sulfate, boric acid and inorganic cross-linking agents such as borate, etc. Can be used alone or in combination of two or more.

  As the resin binder constituting the intermediate layer in the present invention, a modified polyvinyl alcohol having a keto group is preferable, and a cross-linking agent layer containing a compound having two or more primary amino groups in the molecule is provided adjacent to the intermediate layer. It is preferable. By using such a resin binder and a crosslinking agent, it is possible to prevent the recording material from being deteriorated such as bending during conveyance in the thermal transfer recording apparatus or occurrence of cracks in the image receiving layer due to heating history.

  The resin binder having a keto group can be synthesized by a method of copolymerizing a monomer having a keto group and another monomer. Specific examples of the monomer having a keto group include acrolein, diacetone acrylamide, diacetone methacrylate, acetoacetoxyethyl methacrylate, 4-vinylacetoacetanilide, acetoacetylallylamide and the like. Further, a keto group may be introduced by a polymer reaction. For example, an acetoacetyl group can be introduced by a reaction of a hydroxy group or an amino group with a diketene. Specific examples of the resin binder having a keto group include acetoacetyl-modified polyvinyl alcohol, acetoacetyl-modified cellulose derivatives, acetoacetyl-modified starch, diacetone acrylamide-modified polyvinyl alcohol, and resin binders described in JP-A-10-157283. Can be mentioned. In the present invention, modified polyvinyl alcohol having a keto group is particularly preferable. Examples of the modified polyvinyl alcohol having a keto group include acetoacetyl-modified polyvinyl alcohol and diacetone acrylamide-modified polyvinyl alcohol.

  The acetoacetyl-modified polyvinyl alcohol can be produced by a known method such as a reaction between polyvinyl alcohol and diketene. The degree of acetoacetylation is preferably from 0.1 to 20 mol%, more preferably from 1 to 15 mol%. The saponification degree is preferably 80 mol% or more, more preferably 85 mol% or more. The degree of polymerization is preferably 500 to 5000, more preferably 2000 to 4500.

  The diacetone acrylamide modified polyvinyl alcohol can be produced by a known method such as saponification of a diacetone acrylamide-vinyl acetate copolymer. As content of a diacetone acrylamide unit, the range of 0.1-15 mol% is preferable, and also the range of 0.5-10 mol% is preferable. The saponification degree is preferably 85 mol% or more, and the polymerization degree is preferably 500 to 5000.

  In the present invention, the resin binder having a keto group contained in the intermediate layer is crosslinked with a crosslinking agent in an adjacent crosslinking agent layer. Examples of the crosslinking agent include the following compounds.

(1) Polyamines Aliphatic polyamines;
Alkylene diamines (for example, ethylene diamine, propylene diamine, trimethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.),
Polyalkylene polyamines (for example, diethylenetriamine, iminobis (propylamine), bis (hexamethylene) triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, etc.),
・ Substituents of these alkyl or hydroxyalkyl (for example, aminoethylethanolamine, methyliminobis (propylamine), etc.)
Aliphatic or heterocyclic-containing aliphatic polyamines (for example, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, etc.)
・ Aromatic ring-containing aliphatic amines (for example, xylylenediamine, tetrachloro-p-xylylenediamine, etc.)

C4-C15 alicyclic polyamines;
For example, 1,3-diaminocyclohexane, isophorone diamine, menthane diamine, 4,4′-methylene dicyclohexane diamine (hydrogenated methylene dianiline) and the like.

A C4-C15 heterocyclic polyamine;
For example, piperazine, N-aminoethylpiperazine, 1,4-diaminopiperazine and the like.

C6-C20 aromatic polyamines;
Unsubstituted aromatic polyamines (eg 1,2-, 1,3- and 1,4-phenylenediamine, 2,4'- and 4,4'-diphenylmethanediamine, polyphenylpolymethylenepolyamine, diaminodiphenylsulfone, benzidine , Thiodianiline, bis (3,4-diaminophenyl) sulfone, 2,6-diaminopyridine, m-aminobenzylamine, triphenylmethane-4,4 ′, 4 ″ -triamine, naphthylenediamine, etc.)
Aromatic polyamines (eg 2,4- and 2,6-tolylenediamine, crude tolylenediamine, diethyltolylenediamine, 4,4′-) having a nucleus-substituted alkyl group (for example, a C1-C4 alkyl group) Diamino-3,3′-dimethyldiphenylmethane, 4,4′-bis (o-toluidine), dianisidine, diaminoditolylsulfone, 1,3-dimethyl-2,4-diaminobenzene, 1,3-diethyl-2, 4-diaminobenzene, 1,3-dimethyl-2,6-diaminobenzene, 1,4-diethyl-2,5-diaminobenzene, 1,4-diisopropyl-2,5-diaminobenzene, 1,4-dibutyl- 2,5-diaminobenzene, 2,4-diaminomesitylene, 1,3,5-triethyl-2,4-diaminobenzene, 1,3,5- Riisopropyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene, 2,3-dimethyl- 1,4-diaminonaphthalene, 2,6-dimethyl-1,5-diaminonaphthalene, 2,6-diisopropyl-1,5-diaminonaphthalene, 2,6-dibutyl-1,5-diaminonaphthalene, 3,3 ′ , 5,5′-tetramethylbenzidine, 3,3 ′, 5,5′-tetraisopropylbenzidine, 3,3 ′, 5,5′-tetramethyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetraethyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetraisopropyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′- Trabutyl-4,4′-diaminodiphenylmethane, 3,5-diethyl-3′-methyl-2 ′, 4-diaminodiphenylmethane, 3,5-diisopropyl-3′-methyl-2 ′, 4-diaminodiphenylmethane, 3, 3'-diethyl-2,2'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 3,3 ', 5,5'-tetraethyl-4,4'-diaminobenzophenone, 3, 3 ', 5,5'-tetraisopropyl-4,4'-diaminobenzophenone, 3,3', 5,5'-tetraethyl-4,4'-diaminodiphenyl ether, 3,3 ', 5,5'-tetra Isopropyl-4,4′-diaminodiphenylsulfone, etc.)

Polyamide polyamines;
For example, low molecular weight (for example, molecular weight 200 to 5000) obtained by condensation of dicarboxylic acid (such as dimer acid) and excess (more than 2 moles per mole of acid) polyamines: (such as alkylenediamine, polyalkylenepolyamine, etc.) Polyamide polyamine etc.)

Polyether polyamines;
For example, a hydride of cyanoethylated polyether polyol (polyalkylene glycol, etc.) having a molecular weight of 100-5000

(2) Dicyandiamide derivative;
Dicyandiamide, dicyandiamide / formalin polycondensate, dicyandiamide / diethylenetriamine polycondensate, etc.

(3) a hydrazine compound;
Inorganic salts of hydrazine, monoalkyl hydrazine, hydrazine (eg, inorganic salts such as hydrochloric acid, sulfuric acid, nitric acid, nitrous acid, phosphoric acid, thiocyanic acid, carbonic acid), organic salts of hydrazine (eg, organic salts such as formic acid, oxalic acid, etc.) ).

(4) polyhydrazide compounds (dihydrazide, trihydrazide);
Carbohydrazide, succinic acid dihydrazide, adipic acid dihydrazide, citric acid trihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide and the like.

(5) Aldehydes;
Monoaldehyde such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, crotonaldehyde, benzaldehyde, glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleindialdehyde, 1,8-octane dial, phthalaldehyde, isophthalaldehyde , Terephthalaldehyde, dialdehydes such as aldehyde-terminated PVA, side chain aldehyde-containing copolymer obtained by saponifying arylidene acetate vinyl diacetate copolymer, dialdehyde starch, polyacrolein and the like.

(6) methylol compounds;
Methylolphosphine, dimethylolurea, dimethylolmelamine, trimethylolmelamine, urea resin initial polymer, melamine resin initial polymer, and the like.

(7) an activated vinyl compound;
Divinyl sulfone compounds, β-hydroxyethyl sulfone compounds, and the like.

(8) epoxy compound;
Epichlorohydrin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diglycidyl amine, polyepoxy compounds, etc. .

(9) Isocyanate compounds;
Tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane-tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylenebis-4-phenylmethane triisocyanate, isophorone diisocyanate, and their ketoxime block or phenol block, poly An isocyanate etc. are mentioned.

(10) phenolic compounds;
Phenol resin initial condensate, resorcinol resin, etc.

(11) a polyvalent metal salt;
・ Zirconium salt (zirconium nitrate, basic zirconium carbonate, zirconium acetate, zirconium sulfate, zirconium oxychloride, zirconium chloride, hydroxy zirconium chloride, zirconium carbonate, zirconium carbonate / ammonium, zirconium carbonate / potassium, zirconium fluoride compound, etc.)
・ Titanium salts (titanium tetrachloride, titanium lactate, tetraisopropyl titanate, etc.)
・ Aluminum salts (aluminum chloride, aluminum sulfate, aluminum lactate, etc.)
・ Calcium salts (calcium chloride, calcium sulfate, calcium acetate, calcium propionate, etc.)
・ Magnesium salts (magnesium chloride, magnesium sulfate, etc.)
・ Zinc salts (zinc chloride, zinc sulfate, zinc acetate, etc.)

  Among the above-described crosslinking agents, polyhydrazide compounds and polyvalent metal salts are preferable. Among the polyhydrazide compounds, dihydrazide compounds are particularly preferable, and adipic acid dihydrazide and succinic acid dihydrazide are more preferable. As the polyvalent metal salt, a zirconium salt is particularly preferable, and zirconium oxychloride and zirconium nitrate are more preferable. The addition amount of the crosslinking agent is suitably in the range of 1 to 40% by weight, preferably in the range of 2 to 30% by weight, particularly preferably in the range of 3 to 20% by weight, based on the resin binder having a keto group.

  In the present invention, completely or partially saponified polyvinyl alcohol, cation-modified polyvinyl alcohol, and a resin binder having a keto group can be used in combination. In that case, a hardening agent or a crosslinking agent may be used in combination. it can.

  In the present invention, other known resin binders may be used in combination. For example, cellulose derivatives such as carboxymethyl cellulose and hydroxypropyl cellulose, starch and various modified starches, gelatin and various modified gelatins, chitosan, carrageenan, casein, soy protein, polyvinyl alcohol, various modified polyvinyl alcohols, polyvinylpyrrolidone, polyacrylamide, etc. are required It can be used together depending on the situation. Furthermore, various latexes may be used in combination as the binder resin.

The coating amount of the ink receiving layer in the present invention is preferably in the range of 0.05 to 10 g / m ² as the coating amount after drying. The coating amount of the intermediate layer is preferably ¹ to 30 g / m ² as the coating amount after drying. The coating amount of the crosslinking agent layer is preferably in the range of 0.1 to 10 g / ^{m 2.}

  In the present invention, the coating method for the ink receiving layer and the coating method for providing the intermediate layer and the crosslinking agent layer are not particularly limited, and a known coating method can be used. For example, there are a slide bead method, a curtain method, an extrusion method, an air knife method, a roll coating method, a rod bar coating method, and the like.

  Examples of the support used in the present invention include polyethylene, polypropylene, polyvinyl chloride, diacetate resin, triacetate resin, cellophane, acrylic resin, polyethylene terephthalate, polyethylene naphthalate and other water resistant supports such as polyolefin resin-coated paper, Water-absorbing supports such as high-quality paper, art paper, coated paper, cast coated paper and the like are used. Among the water-resistant supports, polyolefin resin-coated paper is preferable, and those having a thickness of about 50 to 250 μm are preferably used.

  When using a support, particularly a film or resin-coated paper which is a water-resistant support, it is preferable to provide a primer layer mainly composed of a natural polymer compound or a synthetic resin on the surface on which the ink receiving layer is provided. The primer layer provided on the support is mainly composed of natural polymer compounds such as gelatin and casein and synthetic resins. Examples of such synthetic resins include acrylic resins, polyester resins, vinylidene chloride, vinyl chloride resins, vinyl acetate resins, polystyrene, polyamide resins, polyurethane resins, and the like. The primer layer is provided on the support with a film thickness (dry film thickness) of 0.01 to 5 μm. Preferably it is the range of 0.01-2 micrometers.

  Various back coat layers can be coated on the support in the present invention for writing property, antistatic property, transportability, curl resistance and the like. The backcoat layer can contain an appropriate combination of inorganic antistatic agents, organic antistatic agents, hydrophilic binders, latexes, pigments, curing agents, surfactants, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the content of this invention is not restricted to an Example. In addition, a part and% show a mass part and mass%.

(Preparation of recording material 1)
<Preparation of polyolefin resin-coated paper support>
A 1: 1 mixture of hardwood bleached kraft pulp (LBKP) and softwood bleached sulfite pulp (NBSP) was beaten to 300 ml with Canadian Standard Freeness to prepare a pulp slurry. As a sizing agent, alkylketene dimer is 0.5% to pulp, polyacrylamide is 1.0% to pulp, and cationized starch is 2.0% to pulp. Polyamide epichlorohydrin resin is 0 to pulp. 0.5% was added and diluted with water to make a 1% slurry. This slurry was made with a long paper machine to a basis weight of 170 g / m ² , dried and conditioned to obtain a polyolefin resin-coated paper base paper. In papermaking the base paper, the density of 0.969 g / cm 70 parts high-density polyethylene resin ² and density 0.918 g / cm ² low-density polyethylene resin 30 parts blend resin composition was melted at 320 ° C., to a thickness of 30μm Extrusion-coating so as to be, extrusion-coated using a roughened cooling roll, the back side, the other side of the resin of 100 parts of low-density polyethylene having a density of 0.918 g / cm ² , A polyethylene resin composition in which 10 parts of anatase-type titanium is uniformly dispersed is melted at 320 ° C., extrusion-coated so as to have a thickness of 35 μm, and extrusion-coated using a cooling roll having a finely roughened surface. Receiving layer coating surface).

The surface of the polyolefin resin-coated paper support was subjected to a high-frequency corona discharge treatment, and then an undercoat layer having the following composition was applied and dried so that the amount of gelatin adhered was 35 mg / m2.
<Undercoat layer>
Gelatin 100 parts Sulfosuccinic acid-2-ethylhexyl ester salt 2 parts Chrome alum 8 parts

On the undercoat layer, a crosslinker coating solution 1 having the following composition is applied by a reverse gravure device, and hot air at 70 ° C. is sequentially blown and dried, and then the intermediate layer coating solution 1 is applied using a slide bead coating device. Then, hot air of 50 ° C. and 60 ° C. was blown in order and dried. Furthermore, the ink receiving layer coating liquid was applied with a microgravure apparatus and dried by blowing hot air at 70 ° C. The coating amount of the crosslinking agent layer is 3 g / m ² , the coating amount of the intermediate layer coating liquid 1 is 21 g / m ^{2 in} terms of silica solid content, and the coating amount of the ink receiving layer is 3 g / m ² .

<Crosslinking agent layer coating solution 1>
Adipic acid dihydrazide 50 parts Polyvinyl alcohol 50 parts (saponification degree 88%, average polymerization degree 500)
It adjusted with water so that solid content concentration might be 16%.

<Preparation of silica dispersion 1>
After adding 4 parts of dimethyldiallylammonium chloride homopolymer (molecular weight 9,000) and 100 parts of gas phase method silica (average primary particle diameter 7 nm, specific surface area 300 m ² / g) to water to prepare a preliminary dispersion, a high-pressure homogenizer Was passed twice under a pressure of 30 MPa to produce a silica dispersion 1 having a solid content concentration of 20%. The average secondary particle size was 140 nm.

<Intermediate layer coating solution 1>
Silica dispersion 1 (as silica solid content) 100 parts acetoacetyl-modified polyvinyl alcohol 20 parts (degree of acetoacetylation 3%, degree of saponification 98%, average degree of polymerization 2350)
Boric acid 4 parts Nonionic surfactant 0.3 parts (Polyoxyethylene alkyl ether)
It adjusted with water so that solid content concentration might be 11.2%.

At the stage of applying the intermediate layer, the cross section of the coating layer was observed with a scanning electron microscope, the coating layer thickness was measured, and the volume fraction of air was determined. The volume fraction of air in the intermediate layer was 0.61. It was confirmed that a porous coating layer was obtained.
<Ink-receiving layer coating solution>
Polyester resin emulsion 1 100 parts (terephthalic acid, isophthalic acid as carboxylic acid component, emulsion of polyester resin polymerized using ethylene glycol and neopentyl glycol as alcohol component, glass transition temperature = 65 ° C.)

(Preparation of recording sheet 2)
The recording sheet 1 was prepared in the same manner as the recording sheet 1 except that the intermediate layer coating solution 1 was changed to the intermediate layer coating solution 2 and the crosslinking agent layer coating solution was not applied.
<Intermediate layer coating solution 2>
Silica dispersion 1 (as silica solid content) 100 parts polyvinyl alcohol 23 parts (saponification degree 88%, average polymerization degree 3500)
Boric acid 4 parts Nonionic surfactant 0.3 parts (Polyoxyethylene alkyl ether)
It adjusted with water so that solid content concentration might be 12.8%.

(Preparation of recording sheet 3)
In the preparation of the silica dispersion of the recording sheet 1, it was prepared in the same manner as the recording sheet 1 except that the set pressure of the high-pressure homogenizer was changed to one pass of 30 MPa and the average secondary particle diameter of silica was 455 nm.

(Preparation of recording sheet 4)
In the preparation of the silica dispersion of the recording sheet 2, the recording sheet 2 was prepared in the same manner as the recording sheet 2 except that the setting pressure of the high-pressure homogenizer was changed to one pass of 30 MPa and the average secondary particle diameter of silica was 455 nm.

(Preparation of recording sheet 5)
The recording sheet 1 was prepared in the same manner as the recording sheet 1 except that an alumina dispersion was used instead of the silica dispersion.
<Alumina dispersion>
Water in acetic acid (10% aqueous solution) 2 parts of γ-alumina powder (average primary particle diameter 16 nm, specific surface area 185 m ² / g) were added 100 parts of water was prepared preliminary dispersion was treated with a homogenizer, An alumina dispersion having a solid content of 20% was produced. The average secondary particle size was 168 nm.

(Preparation of recording sheet 6)
The recording sheet 2 was prepared in the same manner as the recording sheet 2 except that the alumina dispersion 1 was used instead of the silica dispersion 1 of the recording sheet 2.

(Preparation of recording sheet 7)
The recording sheet 1 was prepared in the same manner as the recording sheet 1 except that the silica dispersion liquid 2 was used instead of the silica dispersion liquid 1 and the intermediate layer coating liquid 3 was used.
<Preparation of silica dispersion 2>
After adding 4 parts of dimethyldiallylammonium chloride homopolymer (molecular weight 9,000) and 100 parts of wet process silica (average primary particle diameter 15 nm) to water to prepare a preliminary dispersion, 82% of 0.2 μm diameter zirconia beads were prepared. A silica dispersion 2 having a solid content concentration of 30% was produced by a twice-pass treatment using a bead mill filled at a filling rate of 2%. The average secondary particle size was 143 nm.

<Intermediate layer coating solution 3>
Silica dispersion 2 (as silica solid content) 100 parts acetoacetyl-modified polyvinyl alcohol 21 parts (acetoacetylation degree 3%, saponification degree 98%, average polymerization degree 2350)
Boric acid 5 parts Nonionic surfactant 0.3 parts (Polyoxyethylene alkyl ether)
It adjusted with water so that solid content concentration might be 14.1%.

At the stage of applying the intermediate layer, the cross section of the coating layer was observed with a scanning electron microscope, the coating layer thickness was measured, and the volume fraction of air was determined. The volume fraction of air in the intermediate layer was 0.59. It was confirmed that a porous coating layer was obtained.

(Preparation of recording sheet 8)
In place of the ink-receiving layer coating solution of the recording sheet 1 and the polyester resin emulsion 1, the polyester resin 2 (terephthalic acid, isophthalic acid, sebacic acid as the carboxylic acid component, and ethylene glycol or neopentyl glycol as the alcohol component) is used. It was produced in the same manner as the recording sheet 1 except that a polymerized polyester resin emulsion (glass transition temperature = 21 ° C.) was used.

(Preparation of recording sheet 9)
In the preparation of the silica dispersion of the recording sheet 1, it was prepared in the same manner as the recording sheet 1 except that the set pressure of the high-pressure homogenizer was changed to one pass of 23 MPa and the average secondary particle diameter of silica was 566 nm.

(Preparation of recording sheet 10)
The recording sheet 1 was prepared in the same manner as the recording sheet 1 except that the ink receiving layer was not applied.

(Preparation of recording sheet 11)
The recording sheet 1 is the same as the recording sheet 1 except that a commercially available acrylic emulsion (emulsion obtained by self-emulsification polymerization using PVA as a protective colloid, glass transition temperature 33 ° C.) is used in place of the ink-receiving layer coating solution of the recording sheet 1 and the polyester resin emulsion 1. It produced similarly.

(Preparation of recording sheet 12)
The recording sheet except that a commercially available styrene acrylic emulsion (emulsion polymerized with PVA as a protective colloid, glass transition temperature = −27 ° C.) was used in place of the ink-receiving layer coating solution of the recording sheet 1 and the polyester resin emulsion 1. 1 was prepared.

(Preparation of recording sheet 13)
The recording sheet 1 was prepared in the same manner as the recording sheet 1 except that the intermediate layer coating solution 1 was changed to the intermediate layer coating solution 4 and the crosslinking agent layer coating solution was not applied.
<Intermediate layer coating solution 4>
100 parts of polyvinyl alcohol (saponification degree 88%, average polymerization degree 3500)
It adjusted with water so that solid content concentration might be 5.8%.

(Preparation of recording sheet 14)
The recording sheet 1 was prepared in the same manner as the recording sheet 1 except that the intermediate layer coating solution 1 was changed to the intermediate layer coating solution 5 and the crosslinking agent layer coating solution was not applied.
<Intermediate layer coating solution 5>
Hollow pigment 13.5 parts (particle diameter 1.0 μm, density 0.56 g / cm 3, styrene-acrylic copolymer)
Polyvinyl alcohol 86.5 parts (saponification degree 98%, average polymerization degree 1750)

  Table 1 shows the results of the obtained recording sheets according to the following evaluation methods.

<Print density>
Each recording material was subjected to solid printing of C, G, Y, R, M, B, and K using a sublimation type thermal transfer printer (SELPHY CP-500 manufactured by Canon Inc.), and the printing density was measured using Macbeth RD918. The total value of each color is 9.2 or more: ◯, 8.4 or more and less than 9.2: ◯ △, 7.7 or more and less than 8.4: Δ: 6.9 or more and less than 7.7, Δ ×, 6. Less than 9: judged as x. It can be judged visually that the image is sufficiently colored and vivid.

<Print unevenness>
Using a sublimation thermal transfer printer (SELPHY CP-500 manufactured by Canon Inc.) for each recording material, solid printing of K was performed, and determination was performed based on the following criteria.
○: Printing unevenness is not visible.
○ △: Slight unevenness can be discriminated by comparison with the sample of ○.
Δ: Slight unevenness with no practical problem can be determined.
Δ: Clear printing unevenness
X: Unclear unevenness or print defect apparently practical.

<Gloss difference>
A sublimation type thermal transfer printer (SELPHY CP-500 manufactured by Canon Inc.) was used for each recording material, solid K (100%, 50 printing) was performed, and the following criteria were used.
○: Gloss difference is not felt between the printing part and non-printing.
○ △: A slight difference in gloss can be determined by comparison with the sample of ○.
(Triangle | delta): The slight gloss difference which is satisfactory practically can be discriminate | determined.
Δ ×: Clear gloss difference.
X: There is a clear gloss difference which has a practical problem.

<Transport crack>
A sublimation thermal transfer printer (SELPHY CP-500 manufactured by Canon Inc.) was used for each recording material, and K was printed on the entire surface.
○: There is no crack of the coating layer due to conveyance.
Δ: A slight crack is partially observed.
X: A clear conveyance crack is seen.

<Blister>
A sublimation thermal transfer printer (SELPHY CP-500 manufactured by Canon Inc.) was used for each recording material, and the entire surface of K was printed, and the state of occurrence at the printing portion was observed, and the following criteria were used.
○: No blister occurs.
(Triangle | delta): Generation | occurrence | production is seen slightly and image quality is inferior compared with a good quality ((circle)).
X: Clear occurrence is observed, and the image quality is clearly impaired.

  As is apparent from the above results, it can be seen that the recording sheets 1 to 6 of the present invention have high printing density and are free from printing unevenness, gloss difference, conveyance cracking, and blistering.

Claims (3)

  A porous intermediate layer containing inorganic fine particles having an average secondary particle diameter of 500 nm or less and a resin binder was provided on the support, and an ink receiving layer mainly comprising a polyester resin was provided on the intermediate layer. A thermal transfer recording material characterized by   2. The thermal transfer recording material according to claim 1, wherein the inorganic fine particles are one selected from gas phase method silica, alumina hydrate, and wet method silica, or a mixture thereof.   The resin binder is a modified polyvinyl alcohol having a keto group, and a crosslinking agent layer for crosslinking the modified polyvinyl alcohol having a keto group is provided adjacent to the intermediate layer. Thermal transfer recording material.