JP2006043992A - Fog reducing method and thermosensitive transfer recording ink sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique, which prevents the densification and fogging of an image from developing by preventing the fusing phenomenon at the high-speed printing in a dye thermal transfer recording system from developing, and a thermosensitive transfer recording ink sheet. <P>SOLUTION: In the thermosensitive transfer recording method, in which the image is formed by diffusing the thermally diffusible coloring matter in an ink layer into an image receiving sheet through the heating in response to a recording signal under the condition that the thermosensitive transfer recording image receiving sheet laminated at least with a thermally diffusible coloring matter accepting layer on a support and the thermosensitive transfer recording ink sheet, which is formed by providing the ink layer including at least the thermally diffusible coloring matter are piled up each other, fine particles having the size, which is 20-500% of the film thickness of the ink layer, is added to the ink layer of the thermosensitive transfer recording ink sheet under the printing conditions, the line period in which is not more than 1.5 ms/line. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fog reduction method under high-speed printing conditions of a dye thermal transfer recording method and a thermal transfer recording ink sheet used therefor, and more specifically, to a fog reduction method compatible with high density during high-speed printing and to this The present invention relates to an ink sheet for thermal transfer recording to be used.

  Conventionally, as a color or monochrome image forming technique, an ink sheet containing a heat diffusible dye having a property of diffusing and transferring by heating is opposed to an image receiving layer of an image receiving sheet, and a thermal printing unit such as a thermal head or a laser. There is known a technique for forming an image (so-called dye thermal transfer system) by transferring the thermal diffusible dye to the image receiving layer in an image-like manner. Such a thermal transfer method is well-established as a method that enables image formation using digital data, does not use a processing solution such as a developer, and can form a high image quality comparable to a silver salt photograph.

  However, a new problem has been found in the process of requesting a higher printing speed. That is, if the printing speed is increased by the dye thermal transfer method, the density tends to increase in the low density area, and before the sufficient density is obtained in the high density area, the ink layer of the ink sheet and the image receiving sheet It has been found that the layers tend to be fused by heat. In particular, the fusing phenomenon that occurs in a high density region is a serious problem because it hinders high image density.

  On the other hand, in the dye thermal transfer system, the fusing phenomenon between the ink layer and the image receiving layer is a well-known phenomenon, and various countermeasure techniques have been proposed. For example, as a countermeasure technique for the image receiving sheet, Patent Documents 1, 2, 3 and the like describe techniques for incorporating various modified silicone resins into the image receiving layer. Patent Document 4 discloses a technique for containing an organic filler and a silicone compound in an image receiving layer, and Patent Document 5 discloses a mold release comprising an inorganic powder surface-treated with a mold release material on the surface of a receiving layer and a resin binder. Techniques for providing layers are described. As a countermeasure technique for the ink sheet, Patent Document 6 has a configuration in which the ink layer contains a phosphate ester-based surfactant and a fluorinated fatty acid-modified silicone, and Patent Document 7 has a silicon graft polymer and a polysiloxane compound in the ink layer. Patent Document 8 describes a structure containing a phosphate ester in an ink layer. Further, Patent Document 9 describes a technique for providing a layer made of particles and a polymer substance between a base material and an ink layer in the claims, and further describes a configuration in which the ink layer contains particles as a conventional technique. However, it is described that the concentration is remarkably lowered in the conventional technique in which particles are included in the ink layer.

As a result of intensive investigations on the improvement of the fusing phenomenon in the high density region during the high-speed printing, the present inventors have prevented the fusion by adding particles to the ink layer, and the density of the high-density portion during the high-speed printing. It has been found that fogging is reduced as an unexpected effect.
JP 60-34988 A JP-A 61-27290 Japanese Patent Laid-Open No. 1-229689 JP-A-5-330252 JP-A-6-155950 JP-A-1-200900 JP-A-9-202059 Japanese Patent Laid-Open No. 10-67182 Japanese Patent Laid-Open No. 60-240495

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object the technology for preventing fogging as well as increasing the density by preventing the fusing phenomenon during high-speed printing in the dye thermal transfer recording method, and the thermal transfer recording used therefor. It is to provide an ink sheet.

The above object of the present invention is achieved by the following configurations.
1. An image-receiving sheet for thermal transfer recording in which at least a heat-diffusible dye-receiving layer is laminated on a support, and a heat-sensitive transfer recording ink sheet in which an ink layer containing at least a heat-diffusible dye is provided on the support are superimposed, In a thermal transfer recording method in which an image is formed by diffusing the heat diffusible dye in the ink layer to the image receiving sheet by heating in accordance with a recording signal, in a printing condition in which a line cycle is 1.5 msec / line or less, A fog reduction method during thermal transfer recording, characterized in that fine particles having a size of 20% to 500% of the thickness of the ink layer are added to the ink layer of the thermal transfer recording ink sheet.

2. 2. The fog reduction method according to 1 above, wherein the fine particles are inorganic fine particles.

3. 2. The fog reduction method according to 1 above, wherein the fine particles are fine particles made of an organic polymer material.

4). The inorganic fine particles are added in an amount of 0.5 wt% to 120 wt% of a solid content excluding the fine particles added from the whole ink layer of the ink layer to which the fine particles are added. 2. The fog reduction method according to 2.

5. The addition amount of the fine particles of the organic polymer material is 0.1 wt% to 20 wt% of the solid content excluding the fine particles added from the whole ink layer of the ink layer to which the fine particles are added. 4. The fog reduction method according to 3 above.

6). An image-receiving sheet for thermal transfer recording in which at least a heat-diffusible dye-receiving layer is laminated on a support, and a heat-sensitive transfer recording ink sheet in which an ink layer containing at least a heat-diffusible dye is provided on the support are superimposed, Thermal transfer recording ink for forming an image by diffusing the thermally diffusible dye in the ink layer to the image receiving sheet by heating in accordance with a recording signal under a printing condition of a line cycle of 1.5 msec / line or less An ink sheet for thermal transfer recording, wherein the ink layer of the thermal transfer recording ink sheet in the previous period contains fine particles having a size of 20% to 500% of the thickness of the ink layer.

7). 7. The thermal transfer recording ink sheet as described in 6 above, wherein the fine particles are inorganic fine particles.

8). 7. The thermal transfer recording ink sheet as described in 6 above, wherein the fine particles are fine particles made of an organic polymer material.

9. The inorganic fine particles are added in an amount of 0.5 wt% to 120 wt% of a solid content excluding the fine particles added from the whole ink layer of the ink layer to which the fine particles are added. 8. The thermal transfer recording ink sheet according to 7.

10. The addition amount of the fine particles of the organic polymer material is 0.1 wt% to 20 wt% of the solid content excluding the fine particles added from the whole ink layer of the ink layer to which the fine particles are added. 9. The thermal transfer recording ink sheet as described in 8 above.

11. The thermal diffusible dye-receiving layer of the thermal transfer recording image-receiving sheet contains a metal ion-containing compound, and the thermal diffusible dye contained in the ink layer of the thermal transfer recording ink sheet contains a metal ion-containing compound and a chelate complex. 6. The fog reduction method according to any one of 1 to 5, which is a heat-diffusible dye that can be formed.

12 The thermal diffusible dye-receiving layer of the thermal transfer recording image-receiving sheet contains a metal ion-containing compound, and the thermal diffusible dye contained in the ink layer of the thermal transfer recording ink sheet contains a metal ion-containing compound and a chelate complex. 11. The thermal transfer recording ink sheet as described in any one of 6 to 10 above, which is a heat-diffusible dye that can be formed.

  According to the present invention, it is possible to provide a protective layer transfer sheet used in a post-chelation technique for forming an image having high density, excellent sensitivity, surface physical properties, and image storage stability, and an image forming method using the same. .

Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.
As a result of intensive studies in view of the above problems, the present inventors have improved the fusion phenomenon in the high density region during high-speed printing by adding particles to the ink layer, and at the same time, prevents fogging at a high density. As a result, the present inventors have found that an improved image can be obtained and have reached the present invention.

Details of the present invention will be described below.
<Ink sheet for thermal transfer recording>
[Base material sheet]
As a base material sheet used for the thermal transfer recording ink sheet (hereinafter also referred to as a thermal transfer sheet) according to the present invention, conventionally known materials can be used as the base material sheet of the thermal transfer recording ink sheet. . Specific examples of preferred substrate sheets are thin papers such as glassine paper, condenser paper, paraffin paper, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyphenylene sulfide, polyether ketone, polyether sulfone and other high heat resistant polyesters. Polypropylene, fluororesin, polycarbonate, cellulose acetate, polyethylene derivatives, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, polymethylpentene, ionomer, etc. The thing which was done is mentioned. The thickness of the base sheet can be appropriately selected depending on the material so that the strength, heat resistance and the like are appropriate, but usually a thickness of about 1 to 100 μm is preferably used.

  Moreover, when adhesion with the ink layer formed on the surface of the base sheet is poor, it is preferable to perform primer treatment or corona treatment on the surface.

[Ink layer]
The ink layer constituting the thermal transfer recording ink sheet according to the present invention contains at least a heat-diffusible dye, a binder resin, and fine particles according to the present invention.

<Dye>
The dye used in the ink layer according to the present invention is an azo-based, azomethine-based, methine-based, anthraquinone-based, quinophthalone-based, naphthoquinone-based, or the like used in a heat-sensitive transfer recording ink sheet of a known heat-sensitive sublimation transfer method. Any dye can be mentioned and is not particularly limited. Specific examples of yellow pigments include Holon Brilliant Yellow 6GL, PTY-52, and Macrolex Yellow 6G. Examples of red pigments include MS Red G, Macrolex Red Violet R, Ceres Red 7B, Samaron Red HBSL, and SK. Rubin SEGL and the like, and as blue pigments, Kayaset Blue 714, Waxoline Blue AP-FW, Holon Brilliant Blue S-R, MS Blue 100, Daito Blue No. 1 etc. are mentioned.

The heat-diffusible dye capable of forming a chelate is not particularly limited as long as thermal transfer is possible, and various known compounds can be appropriately selected and used. For example, JP-A-59-78893 Gazette, 59-109349, JP-A-4-94974, 4-97894, 9-123620, 9-131973, 11-78285, 2002-255171. Cyan dyes, magenta dyes, yellow dyes and the like described in JP-A Nos. 2002-234266, 2856335 and 3125236 can be used.
For example, examples of the chelate cyan dye include compounds represented by the following general formula (1).

In the general formula (1), R ₁₁ , R ₁₂ and R ₁₃ each represents a substituted or unsubstituted aliphatic group, and R ₁₁ and R ₁₂ may be the same or different. Examples of the aliphatic group include an alkyl group, a cycloalkyl group, an alkenyl group, and an alkynyl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and an i-propyl group. Examples of a group that can replace these alkyl groups include a linear or branched alkyl group (for example, a methyl group). Group, ethyl group, i-propyl group, t-butyl group, n-dodecyl group, 1-hexylnonyl group, etc.), cycloalkyl group (for example, cyclopropyl group, cyclohexyl group, bicyclo [2.2.1]) Heptyl group, adamantyl group and the like), alkenyl group (for example, 2-propylene group, oleyl group, etc.), aryl group (for example, phenyl group, ortho-tolyl group, ortho-anisyl group, 1-naphthyl group, 9- Anthranyl group, etc.), heterocyclic group (for example, 2-tetrahydrofuryl group, 2-thiophenyl group, 4-imidazolyl group, 2-pyridyl group, etc.) Halogen atom (eg, fluorine atom, chlorine atom, bromine atom), cyano group, nitro group, hydroxy group, carbonyl group (eg, alkylcarbonyl group such as acetyl group, trifluoroacetyl group, pivaloyl group, benzoyl group, pentane) Fluorobenzoyl group, arylcarbonyl group such as 3,5-di-t-butyl-4-hydroxybenzoyl group), oxycarbonyl group (for example, methoxycarbonyl group, cyclohexyloxycarbonyl group, n-dodecyloxycarbonyl group, etc.) Aryloxycarbonyl groups such as alkoxycarbonyl group, phenoxycarbonyl group, 2,4-di-t-amylphenoxycarbonyl group, 1-naphthyloxycarbonyl group, 2-pyridyloxycarbonyl group, 1-phenylpyrazolyl-5-oxy Carbonyl Heterocyclic oxycarbonyl groups, etc.), carbamoyl groups (for example, dimethylcarbamoyl groups, 4- (2,4-di-t-amylphenoxy) butylaminocarbonyl groups and other alkylcarbamoyl groups, phenylcarbamoyl groups, 1-naphthyl Arylcarbamoyl group such as carbamoyl group), alkoxy group (for example, methoxy group, 2-ethoxyethoxy group, etc.), aryloxy group (for example, phenoxy group, 2,4-di-t-amylphenoxy group, 4- (4 -Hydroxyphenylsulfonyl) phenoxy group), heterocyclic oxy group (for example, 4-pyridyloxy group, 2-hexahydropyranyloxy group, etc.), carbonyloxy group (for example, acetyloxy group, trifluoroacetyloxy group, Alkylcarbonyloxy groups such as pivaloyloxy group, Zoyloxy group, aryloxy group such as pentafluorobenzoyloxy group), urethane group (for example, alkylurethane group such as N, N-dimethylurethane group, N-phenylurethane group, N- (p-cyanophenyl) urethane group Aryl urethane groups, etc.), sulfonyloxy groups (for example, methanesulfonyloxy groups, trifluoromethanesulfonyloxy groups, alkylsulfonyloxy groups such as n-dodecanesulfonyloxy groups, benzenesulfonyloxy groups, p-toluenesulfonyloxy groups, etc.) An arylsulfonyl group such as a dimethylamino group, a cyclohexylamino group, an alkylamino group such as an n-dodecylamino group, an anilino group, an arylamino group such as a pt-octylanilino group, etc.) , Sulfonylamino group ( For example, methanesulfonylamino group, heptafluoropropanesulfonylamino group, alkylsulfonylamino group such as n-hexadecylsulfonylamino group, p-toluenesulfonylamino group, arylsulfonylamino group such as pentafluorobenzenesulfonylamino), Famoylamino group (for example, alkylsulfamoylamino group such as N, N-dimethylsulfamoylamino group, arylsulfamoylamino group such as N-phenylsulfamoylamino group), acylamino group (for example, Alkylcarbonylamino group such as acetylamino group, myristoylamino group, arylcarbonylamino group such as benzoylamino group, etc., ureido group (for example, alkylureido group such as N, N-dimethylaminoureido group, N-phenylurea, etc.) Group, arylureido groups such as N- (p-cyanophenyl) ureido group), sulfonyl groups (eg, alkylsulfonyl groups such as methanesulfonyl group and trifluoromethanesulfonyl group, arylsulfonyl groups such as p-toluenesulfonyl group) ), Sulfamoyl groups (for example, dimethylsulfamoyl groups, alkylsulfamoyl groups such as 4- (2,4-di-t-amylphenoxy) butylaminosulfonyl group, arylsulfamo groups such as phenylsulfamoyl group) Moyl group etc.), alkylthio group (eg methylthio group, t-octylthio group etc.), arylthio group (eg phenylthio group etc.), heterocyclic thio group (eg 1-phenyltetrazole-5-thio group, 5-methyl) -1,3,4-oxadiazol-2-thio group and the like.

  Examples of the cycloalkyl group and the alkenyl group are the same as the above substituents. Examples of the alkynyl group include 1-propyne, 2-butyne, 1-hexyne and the like.

As R ₁₁ and R ₁₂ , a group that forms a non-aromatic cyclic structure (eg, pyrrolidine ring, piperidine ring, morpholine ring, etc.) is also preferable.

R ₁₃ is preferably an alkyl group, a cycloalkyl group, an alkoxy group or an acylamino group among the above substituents. n represents an integer of 0 to 4, and when n is 2 or more, the plurality of R ₁₃ may be the same or different.

R ₁₄ is an alkyl group, and examples thereof include a methyl group, an ethyl group, an i-propyl group, a t-butyl group, an n-dodecyl group, and a 1-hexylnonyl group. R ₁₄ is preferably a secondary or tertiary alkyl group, and examples of a preferable secondary or tertiary alkyl group include an isopropyl group, a sec-butyl group, a tert-butyl group, and a 3-heptyl group. The most preferred substituent for R14 is an isopropyl group or a tert-butyl group. The alkyl group of R ₁₄ may be substituted, but is all substituted with a substituent consisting of a carbon atom and a hydrogen atom. They are not substituted with substituents containing other atoms.

R ₁₅ is an alkyl group, and examples thereof include an n-propyl group, i-propyl group, t-butyl group, n-dodecyl group, 1-hexylnonyl group and the like. R ₁₅ is preferably a secondary or tertiary alkyl group, and examples of a preferable secondary or tertiary alkyl group include an isopropyl group, a sec-butyl group, a tert-butyl group, and a 3-heptyl group. The most preferred substituent for R ₁₅ is an isopropyl group or a tert-butyl group. The alkyl group of R ₁₅ may be substituted, but is all substituted with a substituent consisting of a carbon atom and a hydrogen atom. They are not substituted with substituents containing other atoms.

R ₁₆ represents an alkyl group, and examples thereof include n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, isopropyl group, sec-butyl group, tert-butyl group. , 3-heptyl group and the like. Particularly preferred substituents for R ₁₆ are straight-chain alkyl groups having 3 or more carbon atoms, such as n-propyl, n-butyl, n-pentyl, n-hexyl, and n-heptyl. And most preferably an n-propyl group or an n-butyl group. The alkyl group of R ₁₆ may be substituted, but is all substituted with a substituent consisting of a carbon atom and a hydrogen atom, and is not substituted with a substituent containing other atoms.

Specific examples of the compound include, but are not limited to, exemplified compounds 1 to 36 described in JP-A-2002-234266, and the like.
Moreover, as a chelate yellow pigment | dye, the compound represented by following General formula (2) can be mentioned.

In the general formula (2), examples of each substituent represented by R ₁ and R ₂ include a halogen atom, an alkyl group (an alkyl group having 1 to 12 carbon atoms, an oxygen atom, a nitrogen atom, a sulfur atom). Alternatively, a substituent linked by a carbonyl group may be substituted, or an aryl group, alkenyl group, alkynyl group, hydroxyl group, amino group, nitro group, carboxyl group, cyano group or halogen atom may be substituted. Methyl, isopropyl, t-butyl, trifluoromethyl, methoxymethyl, 2-methanesulfonylethyl, 2-methanesulfonamidoethyl, cyclohexyl, etc.), aryl groups (for example, phenyl, 4-t-butylphenyl, 3 -Nitrophenyl, 3-acylaminophenyl, 2-methoxyphenyl, etc. groups), cyano group Alkoxyl group, aryloxy group, acylamino group, anilino group, ureido group, sulfamoylamino group, alkylthio group, arylthio group, alkoxycarbonylamino group, sulfonamido group, carbamoyl group, sulfamoyl group, sulfonyl group, alkoxycarbonyl group, Examples include a heterocyclic oxy group, an acyloxy group, a carbamoyloxy group, a silyloxy group, an aryloxycarbonylamino group, an imide group, a heterocyclic thio group, a phosphonyl group, and an acyl group.

R ₃ represents an alkyl group or an aryl group. Examples of the alkyl group and aryl group represented by R ₃ include the same alkyl groups and aryl groups represented by R ₁ and R ₂ .

Z ₁ represents a 5- to 6-membered aromatic ring constituted with 2 carbon atoms. Specific examples of the 5- to 6-membered aromatic ring constituted with two carbon atoms represented by Z ₁ include benzene, pyridine, pyrimidine, triazine, pyrazine, pyridazine, pyrrole, furan, thiophene and pyrazole. , Imidazole, triazole, oxazole, thiazole and the like, and these rings may further form a condensed ring with other aromatic rings. These rings may have a substituent, and examples of the substituent include the same substituents represented by R1 and R2.

Specific examples of the compound include, but are not limited to, exemplified compounds Y-1 to Y-23 described in Japanese Patent No. 3125236.
Moreover, as a chelate magenta pigment | dye, the compound represented by following General formula (3) can be mentioned.

In the general formula (3), X represents at least a bidentate chelate-forming group or group of atoms, and Y represents a group of atoms forming a 5-membered or 6-membered aromatic hydrocarbon ring or heterocycle. , R ¹ and R ² each represent a hydrogen atom, a halogen atom or a monovalent substituent. n represents 0, 1, 2;
X is particularly preferably a group represented by the following general formula (4).

In the general formula (4), Z ₂ represents an atomic group necessary for forming an aromatic nitrogen-containing heterocyclic ring substituted with at least one group containing a chelatable nitrogen atom. Specific examples of the ring include pyridine, pyrimidine, thiazole, imidazole and the like. These rings may further form a condensed ring with another carbocycle (such as a benzene ring) or a heterocycle (such as a pyridine ring).

  In the above general formula (3), Y represents a group of atoms forming a 5-membered or 6-membered aromatic hydrocarbon ring or heterocyclic ring, and the ring may further have a substituent, and is condensed. You may have a ring. Specific examples of the ring include 3H-pyrrole ring, oxazole ring, imidazole ring, thiazole ring, 3H-pyrrolidine ring, oxazolidine ring, imidazolidine ring, thiazolidine ring, 3H-indole ring, benzoxazole ring, benzimidazole ring, A benzothiazole ring, a quinoline ring, a pyridine ring, etc. are mentioned. These rings may further form a condensed ring with another carbocyclic ring (for example, benzene ring) or a heterocyclic ring (for example, pyridine ring). Examples of substituents on the ring include alkyl groups, aryl groups, heterocyclic groups, acyl groups, amino groups, nitro groups, cyano groups, acylamino groups, alkoxy groups, hydroxy groups, alkoxycarbonyl groups, halogen atoms, etc. The group may be further substituted.

R ¹ and R ² each represent a hydrogen atom, a halogen atom (for example, a fluorine atom, a chlorine atom) or a monovalent substituent, and examples of the monovalent substituent include an alkyl group, an alkoxy group, a cyano group, Examples thereof include an alkoxycarbonyl group, an aryl group, a heterocyclic group, a carbamoyl group, a hydroxy group, an acyl group, and an acylamino group.

  X represents at least a bidentate chelate-forming group or a group of atoms, and may be anything that can form a dye as the general formula (3), such as 5-pyrazolone, imidazole, pyrazolopyrrole, pyrazolopyrazole, pyra Zoloimidazole, pyrazolotriazole, pyrazolotetrazole, barbituric acid, thiobarbituric acid, rhodanine, hydantoin, thiohydantoin, oxazolone, isoxazolone, indandione, pyrazolidinedione, oxazolidinedione, hydroxypyridone, or pyrazolopyridone are preferred .

  Specific examples of the compound include, but are not limited to, exemplified compounds (1) to (56) described in JP-A-9-131973.

<Binder resin>
The ink layer according to the present invention contains a binder resin together with the above-described pigment and fine particles according to the present invention described later.

  As the binder resin used in the ink layer, conventionally known binder resins used in thermal transfer recording ink sheets can be used. Examples thereof include cellulose resins such as cellulose addition compounds, cellulose esters, and cellulose ethers, and polyvinyl resins. Polyvinyl acetal resins such as alcohol, polyvinyl formal, polyvinyl acetoacetal, polyvinyl butyral, polyvinyl pyrrolidone, polyvinyl acetate, polyacrylamide, styrene resin, poly (meth) acrylic acid ester, poly (meth) acrylic acid, (meth) Examples thereof include vinyl resins such as acrylic acid copolymers, rubber resins, ionomer resins, olefin resins, and polyester resins. Among these resins, polyvinyl butyral, polyvinyl acetoacetal or cellulose resin having excellent storage stability is preferable.

  As a binder resin for the ink layer, a reaction product of an isocyanate described in JP-B-5-78437 and a compound having active hydrogen selected from polyvinyl butyral, polyvinyl formal, polyester polyol and acrylic polyol, isocyan The reaction product in which the amount of the reaction product is 10 to 200 parts by weight with respect to 100 parts by weight of the reaction product in which the narate is diisocyanate or triisocyanate and the compound having active hydrogen; An organic solvent-soluble polymer obtained by esterifying and / or urinating an intramolecular hydroxyl group of a synthetic water-soluble polymer, a natural and / or semi-synthetic water-soluble polymer; the degree of acetylation described in JP-A-3-264393 is 2. Cellulose acetate having a total substitution degree of 4 or more and a total substitution degree of 2.7 or more; polyvinyl alcohol (Tg = 8 ° C), polyvinyl acetate (Tg = 32 ° C), vinyl resin such as vinyl chloride / vinyl acetate copolymer (Tg = 77 ° C), polyvinyl butyral (Tg = 84 ° C), polyvinyl acetoacetal (Tg = 110 ° C) Polyvinyl acetal resins such as polyacrylamide (Tg = 165 ° C.), vinyl resins such as aliphatic polyester (Tg = 130 ° C.), and the like; isocyanates described in JP-A-7-52564; A reaction product with polyvinyl butyral in which the mass of the vinyl alcohol part contained is 15 to 40%, the reaction product in which the isocyanate is a diisocyanate or a triisocyanate; described in JP-A-7-32742 Phenylisocyanate-modified polyvinyl acetal resin of general formula (I); JP-A-6-155935 One of the isocyanate-reactive cellulose or isocyanate-reactive acetal resin described above, an isocyanate-reactive acetal resin, an isocyanate-reactive vinyl resin, an isocyanate-reactive acrylic resin, an isocyanate-reactive phenoxy resin, and an isocyanate reaction Cured product of a composition containing one kind of resin selected from a basic polystyrene resin and a polyisocyanate compound; polyvinyl butyral resin (preferably having a molecular weight of 60,000 or more, glass transition temperature of 60 ° C. or more, more preferably 70 ° C. or more 110 ° C. or less, and the vinyl alcohol moiety has a mass percentage of 10 to 40%, preferably 15 to 30% in the polyvinyl butyral resin); acrylic modified cellulose resins and cellulose resins include ethyl cellulose, hydroxyethyl cellulose, Cellulose resins (preferably ethyl cellulose) such as droxycellulose, hydroxypropylcellulose, methylcellulose, cellulose acetate, and butyric acetate cellulose can be used.

  One of these various binder resins can be used alone, or two or more thereof can be used in combination.

<Fine particles>
The ink layer according to the present invention contains fine particles together with the dye and the binder resin.
Examples of the fine particles include inorganic fine particles and organic polymer fine particles.
As inorganic fine particles, conventionally known fine particles such as metals and metal oxides, sulfides and carbonates can be used. Specific examples include silica, talc, kaolin, zeolite, titanium oxide, zinc oxide, magnesium oxide. Iron oxide, nickel oxide, calcium carbonate, potassium carbonate, alumina, boron nitride, molybdenum disulfide, zinc sulfide, barium sulfate, carbon black, titanium, zinc, aluminum, copper, nickel, and the like.

  The addition amount of these inorganic fine particles is preferably in the range of 0.5 to 120% by weight of the solid content of the ink layer to which the inorganic fine particles are added excluding the fine particles added from the entire ink layer.

Examples of the organic fine particles include fine particles of conventionally known organic polymer materials. Specific examples include acrylic resins, silicon resins, styrene resins, melamine resins, benzoguanamine resins, urethane resins, amide resins, urea resins, epoxy resins, and the like.
The addition amount of these organic fine particles is preferably in the range of 0.1 wt% to 20 wt% of the solid content weight of the ink layer to which inorganic fine particles are added excluding the fine particles added from the entire ink layer.

  The particle size of the fine particles of the present invention is an average particle size in the range of 20% to 500% of the thickness of the ink layer for both inorganic particles and organic particles. When the average particle size is larger than the above range, it is effective for fogging and fusing, but the concentration in the high concentration region is rather lowered. The effect is not recognized in all of wearing, covering and density.

  Further, the ink layer according to the present invention may contain various known additives as necessary in addition to the above-described pigment and binder resin. For example, the ink layer may be prepared by dissolving an ink coating solution prepared by dissolving or dispersing the above-described dye, binder resin, or other additive in a suitable solvent by a known means such as a gravure coating method (support body). (The same applies in this specification.) It can be formed by drying after coating. The ink layer according to the present invention may have a thickness of about 0.1 to 3.0 μm, preferably about 0.3 to 1.5 μm.

[Heat resistant slipping layer]
In the thermal transfer sheet according to the present invention, it is preferable to provide a heat-resistant slipping layer on the surface opposite to the ink layer across the base sheet.

  The heat resistant slipping layer is provided for the purpose of preventing thermal fusion between a heating device such as a thermal head and a base sheet, smooth running, and removing deposits on the thermal head.

  Examples of the resin used for the heat resistant slipping layer include cellulose resins such as ethyl cellulose, hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, nitrocellulose, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl Vinyl resins such as acetal and polyvinylpyrrolidone, acrylic resins such as polymethyl methacrylate, polyethyl acrylate, polyacrylamide, and acrylonitrile-styrene copolymers, polyimide resins, polyamide resins, polyamideimide resins, polyvinyltoluene resins, A single or mixture of natural or synthetic resins such as malon indene resin, polyester resin, polyurethane resin, silicone-modified or fluorine-modified urethane is used. It is. In order to further improve the heat resistance of the heat resistant slipping layer, among the above resins, a resin having a hydroxyl group-based reactive group is used, and a polyisocyanate or the like is used in combination as a crosslinking agent. It is preferable to do.

  Further, in order to impart slidability with the thermal head, a solid or liquid release agent or lubricant may be added to the heat-resistant slip layer to give heat-resistant slip. Examples of the release agent or lubricant include various waxes such as polyethylene wax and paraffin wax, higher aliphatic alcohols, organopolysiloxanes, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants. Activators, fluorine surfactants, metal soaps, organic carboxylic acids and derivatives thereof, fluorine resins, silicone resins, fine particles of inorganic compounds such as talc, silica, and the like can be used. The amount of the lubricant contained in the heat resistant slipping layer is 5 to 50% by mass, preferably about 10 to 30% by mass. The thickness of such a heat-resistant slipping layer can be about 0.1 to 10 μm, preferably about 0.3 to 5 μm.

  When the protective transfer layer unit is a laminate of a protective transfer layer and an adhesive layer, the adhesive layer serves to facilitate the transfer of the protective transfer layer to the transfer target. As an adhesive for forming this adhesive layer, it is possible to use a hot-melt adhesive such as acrylic, styrene acrylic, vinyl chloride, styrene-vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer. it can. The adhesive layer can be formed by known means such as gravure coating, gravure reverse coating, roll coating, etc., and the thickness of the adhesive layer is preferably about 0.1 to 5 μm.

<Image-receiving sheet for thermal transfer recording>
Next, an image receiving sheet for thermal transfer recording (hereinafter also referred to as a thermal transfer image receiving sheet) having at least a heat diffusible dye receiving layer on the support according to the present invention will be described.

(Substrate sheet)
The support used in the thermal transfer image-receiving sheet has a role of holding the heat-diffusible dye image-receiving layer and has a mechanical strength that does not hinder handling even in an overheated state because heat is applied during thermal transfer. Is preferred.

The material of such a support is not particularly limited. For example, condenser paper, glassine paper, sulfuric acid paper, high-size paper, synthetic paper (polyolefin-based, polystyrene-based), fine paper, art paper, coated paper , Cast coated paper, wallpaper, backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, paperboard, cellulose fiber paper, or polyester, polyacrylate, polycarbonate, polyurethane, polyimide, polyether Imide, cellulose derivative, polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene, acrylic, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone Examples include polyether sulfone, tetrafluoroethylene, perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene / ethylene, tetrafluoroethylene / hexafluoropropylene, polychlorotrifluoroethylene, and polyvinylidene fluoride. A white opaque film formed by adding a white pigment or a filler to these synthetic resins or a foamed foam sheet can be used, and is not particularly limited.
Moreover, the laminated body by the arbitrary combinations of the said support body can also be used. Examples of typical laminates include cellulose fiber paper and synthetic paper, or synthetic paper of cellulose synthetic paper and a plastic film. The thickness of these substrate sheets may be arbitrary and is usually about 10 to 300 μm.

  In order to obtain higher printing sensitivity and high image quality without density unevenness or white spots, it is preferable to have a layer having fine voids. As the layer having fine voids, a plastic film or synthetic paper having fine voids inside can be used. Moreover, the layer which has a fine space | gap by various coating systems can be formed on various base material sheets. As a plastic film or synthetic paper having fine voids, a polyolefin resin such as polypropylene or a polyester resin such as polyethylene terephthalate is mainly blended with an inorganic pigment and / or a polymer incompatible with polypropylene, and these are voids (voids). ) A plastic film or synthetic paper obtained by stretching and forming a mixture of these as a formation initiator is preferred.

Considering these points, the elastic modulus at 20 ° C. of the plastic film and the synthetic paper is preferably 5 × 10 ⁸ Pa to 1 × 10 ¹⁰ Pa. In addition, since these plastic films and synthetic paper are usually formed by biaxial stretching, they shrink by heating. When these are left at 110 ° C. for 60 seconds, the shrinkage is 0.5 to 2.5%. The plastic film and the synthetic paper described above may be combined with each other as a single layer including fine voids, or may have a plurality of layers. In the case of a plurality of layer configurations, all layers constituting the layer may contain fine voids, or a layer having no fine voids may be contained. A white pigment may be mixed in the plastic film or synthetic paper as a concealing agent as necessary. In order to increase whiteness, an additive such as a fluorescent brightening agent may be included. The layer having fine voids preferably has a thickness of 30 to 80 μm.

  As a layer having fine voids, a layer having fine voids can be formed on a substrate by a coating method. As the plastic resin to be used, known resins such as polyester, urethane resin, polycarbonate, acrylic resin, polyvinyl chloride, and polyvinyl acetate can be used singly or in combination.

In addition, if necessary, a resin such as polyvinyl alcohol, polyvinylidene chloride, polyethylene, polypropylene, modified polyolefin, polyethylene terephthalate, polycarbonate, or the like is provided on the surface of the support opposite to the side on which the image receiving layer is provided for the purpose of preventing curling. Or a layer of synthetic paper. As a bonding method, for example, known lamination methods such as dry lamination, non-solvent (hot melt) lamination, EC lamination method and the like can be used, but preferred methods are dry lamination and non-solvent lamination. An example of an adhesive suitable for the non-solvent lamination method is Takenate 720L manufactured by Takeda Pharmaceutical Co., Ltd., and an example of an adhesive suitable for dry lamination is Takelac A969 / Takenate A manufactured by Takeda Pharmaceutical Co., Ltd. -5 (3/1), manufactured by Showa Polymer Co., Ltd., Polysol PSA SE-1400, Vinylol PSA AV-6200 series and the like. The amount of these adhesives, from about 1-8 g / ^{m 2} on a solids, and preferably from 2 to 6 g / ^{m 2.}

  When the plastic film and the synthetic paper as described above, or between them, or various papers and the plastic film or the synthetic paper are laminated, they can be bonded together with an adhesive layer.

  For the purpose of increasing the adhesive strength between the substrate sheet and the heat diffusible dye-receiving layer, it is preferable to subject the surface of the substrate sheet to various primer treatments and corona discharge treatments.

(Binder resin)
In the thermal transfer image-receiving sheet according to the present invention, a known resin can be used as the binder resin for the image-receiving layer, and among them, a resin that is easily dyed is preferably used. Specifically, polyolefin resins such as polypropylene, halogenated resins such as polyvinyl chloride and polyvinylidene chloride, vinyl resins such as polyvinyl acetate, polyacrylic acid ester, polyvinyl butyral, and polyvinyl acetal, polyethylene terephthalate, and polybutylene Polyester resins such as terephthalate, polystyrene resins such as polystyrene and polystyrene acrylonitrile, polyamide resins, phenoxy resins, copolymers of olefins such as ethylene and propylene with other vinyl monomers, polyurethane, polycarbonate, acrylic resins, ionomers, A simple substance such as a cellulose derivative or a mixture thereof can be used, and among these, polyester resins, vinyl resins, polystyrene resins and cellulose derivatives are preferred. Arbitrariness.

(Release agent)
It is preferable to add a release agent to the heat diffusible dye receiving layer according to the present invention for the purpose of preventing heat fusion with the heat diffusible dye receiving layer. As the mold release agent, a phosphoric ester plasticizer, a fluorine compound, silicone oil (including reaction curable silicone) and the like can be used, and among these, silicone oil is preferable. As the silicone oil, various modified silicones including dimethyl silicone can be used. Specifically, amino-modified silicones, epoxy-modified silicones, alcohol-modified silicones, vinyl-modified silicones, urethane-modified silicones, and the like can be blended or polymerized using various reactions. The release agent may be used alone or in combination of two or more. Further, the addition amount of the release agent is preferably 0.5 to 30 parts by mass with respect to 100 parts by mass of the binder resin for forming the dye image-receiving layer. When the range of the addition amount is not satisfied, there may be a problem such as fusion between the thermal transfer sheet and the dye image-receiving layer of the thermal transfer image-receiving sheet or a decrease in printing sensitivity. These releasing agents may not be added to the dye image-receiving layer, but may be provided separately as a releasing layer on the heat-diffusible dye-receiving layer.

(Metal ion-containing compounds)
In the present invention, a metal ion-containing compound (hereinafter also referred to as a metal source) can be contained in the image receiving layer.

Examples of the metal source include inorganic or organic salts and metal complexes of metal ions, and among them, salts and complexes of organic acids are preferable. Examples of the metal include monovalent and polyvalent metals belonging to Groups I to VIII of the Periodic Table. Among them, Al, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Sn, Ti And Zn are preferable, and Ni, Cu, Cr, Co and Zn are particularly preferable. Specific examples of the metal source include Ni ²⁺ , Cu ²⁺ , Cr ²⁺ , Co ²⁺ and Zn ²⁺ and aliphatic salts such as acetic acid and stearic acid, or aromatic carboxylic acid salts such as benzoic acid and salicylic acid. Can be mentioned.

In the present invention, the metal source is particularly preferably a complex represented by the following general formula (I) because it can be stably added to the binder resin in the post-heating region and is substantially colorless.
Formula (I)
[M (Q ₁ ) _X (Q ₂ ) _Y (Q ₃ ) _Z ] _P ⁺ (L ⁻ ) _P
In the above general formula (I), M represents a metal ion, preferably Ni ²⁺ , Cu ²⁺ , Cr ²⁺ , Co ²⁺ or Zn ²⁺ . Q ₁ , Q _2, and Q ₃ each represent a coordination compound that can coordinately bond with the metal ion represented by M, and may be the same or different from each other. These coordination compounds can be selected from, for example, coordination compounds described in Chelate Science (5) (Nan Edo). L- represents an organic anion group, and specific examples include a tetraphenyl boron anion and an alkylbenzene sulfonate anion. _X represents 1, 2 or 3; _Y represents 1, 2 or 0; _Z represents 1 or 0; _P represents 1 or 2. Specific examples of this type of metal source include compounds exemplified in U.S. Pat. No. 4,987,049 or compound No. 9 exemplified in JP-A-9-39423. 1-99 etc. can be mentioned. Particularly preferred is a compound represented by the following general formula (II) described in JP-A-10-241410.

Formula (II)
M ²⁺ (X ¹⁻ ) ₂
In the general formula (II), M ²⁺ represents a divalent transition metal ion, and among these, nickel and zinc are preferred from the color of the metal ion supply compound itself and the color tone of the chelated dye. X ¹⁻ represents a coordination compound capable of forming a complex with a divalent metal ion. These compounds may have a neutral ligand depending on the central metal, and typical ligands include H ₂ O or NH ₃ .

  The content of the metal ion-containing compound is preferably 1 to 80% by mass, more preferably 1 to 50% by mass, based on the entire image receiving layer.

(Middle layer)
The thermal transfer image receiving sheet may be provided with an intermediate layer between the base sheet and the heat diffusible dye receiving layer. The intermediate layer referred to in the present invention refers to all layers existing between the base sheet and the heat-diffusible dye-receiving layer, and may have a multilayer structure. Examples of the function of the intermediate layer include solvent resistance performance, barrier performance, adhesion performance, white color imparting ability, hiding performance, antistatic function, etc., but are not limited thereto, and all conventionally known intermediate layers can be applied. .

  In order to impart solvent resistance and barrier performance to the intermediate layer, it is preferable to use a water-soluble resin. Examples of water-soluble resins include cellulose resins such as carboxymethyl cellulose, polysaccharide resins such as starch, proteins such as casein, gelatin, agar, and polyvinyl alcohol, ethylene vinyl acetate copolymer, polyvinyl acetate, vinyl chloride, Vinyl acetate copolymers (for example, Veopa manufactured by Japan Epoxy Resin Co., Ltd.), vinyl acetate (meth) acrylic copolymers, (meth) acrylic resins, styrene (meth) acrylic copolymers, vinyl resins such as styrene resins, And polyamide resins such as melamine resin, urea resin and benzoguanamine resin, polyester, polyurethane and the like. The water-soluble resin referred to here is completely dissolved (particle size of 0.01 μm or less), colloidal dispersion (0.01 to 0.1 μm), or emulsion (0.1 to 1 μm) in a solvent mainly composed of water. ) Or a resin in a slurry (1 μm or more) state. Of these water-soluble resins, particularly preferred are alcohols such as methanol, ethanol, and isopropyl alcohol, and dissolution by general-purpose solvents such as hexane, cyclohexane, acetone, methyl ethyl ketone, xylene, ethyl acetate, butyl acetate, and toluene. Of course, it is a resin that does not even swell. In this sense, a resin that is completely soluble in a solvent mainly composed of water is most preferable. In particular, a polyvinyl alcohol resin and a cellulose resin are mentioned.

  In order to give adhesive performance to the intermediate layer, a urethane-based resin and a polyolefin-based resin are generally used depending on the type of the base sheet and its surface treatment. Further, when a thermoplastic resin having active hydrogen and a curing agent such as an isocyanate compound are used in combination, good adhesiveness can be obtained. In order to give the intermediate layer a white color imparting ability, a fluorescent whitening agent can be used. The fluorescent brightening agent used can be any conventionally known compound, including stilbene, distilbene, benzoxazole, styryl-oxazole, pyrene-oxazole, coumarin, aminocoumarin, imidazole, and benzimidazole. -Based, pyrazoline-based, and distyryl-biphenyl-based fluorescent whitening agents. The whiteness can be adjusted by the type and amount of the fluorescent brightener. Any method can be used as the method of adding the optical brightener. That is, a method of adding by dissolving in water, a method of adding by pulverizing and dispersing by a ball mill or a colloid mill, a method of dissolving in a high boiling point solvent and mixing with a hydrophilic colloid solution, and adding as an oil-in-water dispersion, There is a method of impregnating the polymer latex and adding it.

  Further, titanium oxide may be added to the intermediate layer in order to conceal the glaring feeling and unevenness of the base sheet. Furthermore, the use of titanium oxide is preferable in that the degree of freedom in selecting a base sheet is widened. There are two types of titanium oxide: rutile type titanium oxide and anatase type titanium oxide, but considering the effect of whiteness and fluorescent brightening agent, the absorption in the ultraviolet region is shorter than rutile type. Anatase type titanium oxide is preferred. If the binder resin in the intermediate layer is aqueous and titanium oxide is difficult to disperse, use titanium oxide with a hydrophilic treatment on the surface, or disperse it with a known dispersant such as a surfactant or ethylene glycol. be able to. As for the addition amount of a titanium oxide, 10-400 mass parts is preferable as a titanium oxide solid content with respect to 100 mass parts of resin solid content.

  In order to impart an antistatic function to the intermediate layer, a conventionally known conductive material such as a conductive inorganic filler or an organic conductive material such as polyaniline sulfonic acid may be appropriately selected and used in accordance with the intermediate layer binder resin. it can. The thickness of such an intermediate layer is preferably set in the range of about 0.1 to 10 μm.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, “part” and “%” represent “part by weight” and “% by weight”, respectively.

Example 1
<Preparation of thermal transfer ink sheet>
[Preparation of thermal transfer ink sheet 1]
(Coating back coat layer)
A backcoat layer coating solution 1 having the following composition is applied to the surface of a 6 μm thick polyethylene terephthalate film (manufactured by Toray Industries, Inc.) by a gravure coating method and dried, followed by a heat curing treatment. A support A having a back coat layer of 0 μm was produced.

<Preparation of backcoat layer coating solution 1>
Polyvinyl butyral resin (Sekisui Chemical Co., Ltd., ESREC BX-1) 3.5 parts by weight Phosphate ester surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Prisurf A208S)
3.0 parts by weight Phosphate ester surfactant (Phosphanol RD720 manufactured by Toho Chemical Co., Ltd.)
0.3 part by weight Polyisocyanate (Dainippon Ink & Chemicals, Barnock D750-45)
19.0 parts by weight Talc (manufactured by Nippon Talc Co., Ltd. Y / X = 0.03) 0.2 parts by weight Methyl ethyl ketone 35.0 parts by weight Toluene 35.0 parts by weight

(Formation of ink layer)
An ink layer coating liquid having the following composition was applied to the surface opposite to the surface on which the backcoat layer of the prepared support A was provided, and dried to prepare thermal transfer ink sheets 1 to 17 (Table 1). . The thickness of each ink layer after drying was 0.8 μm.

<Ink layer coating solution>
Dye M-1 5.0 parts by weight Polyvinyl acetoacetal resin (manufactured by Sekisui Chemical Co., Ltd., ESREC KS-5)
5.0 parts by weight Fine particles (described in Table 1)
Methyl ethyl ketone 45.0 parts by weight Toluene 45.0 parts by weight

<< Preparation of thermal transfer image-receiving sheet >>
As a base material, on one side of synthetic paper having a thickness of 150 μm (YUPO FPG-150 manufactured by Oji Oil Chemical Co., Ltd.), an image-receiving layer coating liquid having the following composition is solidified by drying using a wire bar coating method. After coating so that the amount was 3 g / m ² , drying was performed at 110 ° C. for 30 seconds to obtain a thermal transfer image receiving sheet 1.

(Image-receiving layer coating solution)
Vinyl chloride vinyl acetate copolymer (Denka Vinyl # 1000A, manufactured by Denki Kagaku Kogyo Co., Ltd.)
3.0 parts by weight Vinyl chloride styrene acrylic copolymer (Denka Lac # 400, manufactured by Denki Kagaku Kogyo Co., Ltd.)
0.7 parts by weight Polyester resin (Toyobo Co., Ltd., Byron 600) 4.6 parts by weight Vinyl-modified silicone (Shin-Etsu Chemical Co., X-62-1212) 0.8 parts by weight Catalyst (Shin-Etsu Chemical Co., Ltd., CAT PLR- 5) CAT PLR-5) 0.4 parts by weight Catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., CAT PL-50T) 0.5 parts by weight Methyl ethyl ketone 30.0 parts by weight Toluene 30.0 parts by weight Isopropyl alcohol 30.0 parts by weight

Example 2
Post-chelate thermal transfer ink sheets 18 to 34 (Table 1) were prepared in the same manner as in Example 1 except that the dye of Example 1 was changed to the post-chelate dye M-2. The thickness of each ink layer after drying was 0.8 μm.
Next, a post-chelate type image-receiving sheet 2 was prepared in the same manner as in Example 1 except that the image-receiving layer coating solution had the following composition.

(Image-receiving layer coating solution)
Polyvinyl butyral resin (Seksui Chemical Co., Ltd. ESREC BX-1) 4.5 parts by weight Metal ion-containing compound (MS-1 * 1) 3.0 parts by weight Methylstyryl modified silicone oil (KF410, Shin-Etsu Chemical Co., Ltd.) 0.5 parts by weight Parts methyl ethyl ketone 80.0 parts by weight butyl acetate 10.0 parts by weight (* 1) MS-1: Ni ²⁺ [C ₇ H ₁₅ COC (COOCH ₃ ) = C (CH ₃ ) O ⁻ ] ₂

Comparative Example 1
Comparative ink sheets 1 to 3 (Comparative-1 to Comparative-3) were prepared in the same manner as in Example 2 except that the fine particles were changed to those shown in Table 2 in Example 2.

<Image formation>
The thermal transfer recording device is mounted with a line thermal head having a heating resistor density of 300 dpi (dpi represents the number of dots per inch), and the image receiving layer portion of the thermal transfer image receiving sheet and the ink layer of the thermal transfer ink sheet are superimposed. The step pattern is sequentially increased in the applied energy range of 5 to 80 mJ / mm ² while being pressed by a thermal head and a platen roll. Line speeds are 3.0 msec / line, 1.5 msec / line, 1.0 msec / An image was formed by heating from the back side of the ink layer at a line of 0.5 msec / line to transfer the dye onto the image receiving layer of the thermal transfer image receiving sheet.

Next, using the same thermal transfer recording apparatus as that used for image formation, the image-receiving sheet on which the image was formed and the protective layer transfer sheet were superimposed, and the applied energy of 60 mJ / mm ² while being pressed by the thermal head and the platen roll The protective layer was transferred to the entire surface of the image receiving sheet by heating from the back side of the protective layer transfer sheet at a feed rate of 2 msec / line. In addition, as the protective layer transfer sheet, the protective layer transfer sheet portion of the ink sheet C-CR / A6 manufactured by Konica Minolta Photo Imaging was used.

<Evaluation>
The following evaluations were performed on each image produced as described above.
(Evaluation of printing density)
The reflection optical density of the maximum density portion of the produced image pattern was measured using a densitometer (X-rite 310), and the print density was evaluated according to the following criteria.

◎: Maximum density is 2.0 or more ○: Maximum density is 1.8 or more and less than 2.0 △: Maximum density is 1.6 or more and less than 1.8 ×: Maximum density is less than 1.6

(Evaluation of fogging)
The above-mentioned image is stored except that the prepared ink sheet is stored in an environment of 50 ° C. and 80% RH for 24 hours, the printing environment is 30 ° C. and 80% RH, and the line speed is only 1.0 msec / line. An image was formed in the same manner as the forming method. The reflection optical density of the white background portion of the image (the portion where only the protective layer other than the colored image pattern is transferred) and the image receiving sheet before printing are measured using a densitometer (X-rite 310) and evaluated according to the following criteria: went.

A: The difference between the density of the white background after printing and the density of the image receiving sheet before printing is less than 0.005. ○: The difference between the density of the white background after printing and the density of the image receiving sheet before printing is 0.005 or more. Less than 01 Δ: The difference between the density of the white background after printing and the density of the image receiving sheet before printing is 0.01 or more and less than 0.02 ×: The difference between the density of the white background after printing and the density of the image receiving sheet before printing 0.02 or more

(Evaluation of fusion)
The state of fusing phenomenon between the image receiving layer and the ink layer in the transfer process of the dye from the ink sheet during the image formation in the environment of 30 ° C. and 80% RH performed in the evaluation of the fog was observed, and the following criteria were used. Evaluation was performed.

A: No abnormal noise was generated and no fusing phenomenon occurred.
○: Slight abnormal noise was generated, but no fusion phenomenon occurred.
Δ: Abnormal noise was generated, and the ink layer and the image receiving layer were fused at the maximum density portion of the image pattern.
X: An abnormal sound was generated, and the ink layer and the image receiving layer were fused at a portion other than the maximum density portion of the image pattern.
The above evaluation results are shown in Tables 3 and 4.

The results of the comparative examples shown in Table 4 cannot satisfy all of the printing density, fogging and fusing under printing conditions of 1.5 msec / line or less, but as shown in Table 3, the fine particles of the present invention In the case of using an ink sheet containing, even under printing conditions of 1.5 msec / line or less, a high maximum density can be obtained without causing a fusing phenomenon, fog is prevented, and an image with less fog is obtained. available.

Claims (12)

An image-receiving sheet for thermal transfer recording in which at least a heat-diffusible dye-receiving layer is laminated on a support, and a heat-sensitive transfer recording ink sheet in which an ink layer containing at least a heat-diffusible dye is provided on the support are superimposed, In a thermal transfer recording method in which an image is formed by diffusing the heat diffusible dye in the ink layer to the image receiving sheet by heating in accordance with a recording signal, in a printing condition in which a line cycle is 1.5 msec / line or less, A fog reduction method during thermal transfer recording, characterized in that fine particles having a size of 20% to 500% of the thickness of the ink layer are added to the ink layer of the thermal transfer recording ink sheet. The fog reduction method according to claim 1, wherein the fine particles are inorganic fine particles. The fog reduction method according to claim 1, wherein the fine particles are fine particles made of an organic polymer material. The amount of the inorganic fine particles added is 0.5 wt% to 120 wt% of a solid content excluding the fine particles added from the whole ink layer of the ink layer to which the fine particles are added. Item 3. The fog reduction method according to Item 2. The addition amount of the fine particles of the organic polymer material is 0.1 wt% to 20 wt% of the solid content excluding the fine particles added from the whole ink layer of the ink layer to which the fine particles are added. The fog reduction method according to claim 3. An image-receiving sheet for thermal transfer recording in which at least a heat-diffusible dye-receiving layer is laminated on a support, and a heat-sensitive transfer recording ink sheet in which an ink layer containing at least a heat-diffusible dye is provided on the support are superimposed, Thermal transfer recording ink for forming an image by diffusing the thermally diffusible dye in the ink layer to the image receiving sheet by heating in accordance with a recording signal under a printing condition of a line cycle of 1.5 msec / line or less An ink sheet for thermal transfer recording, wherein the ink layer of the thermal transfer recording ink sheet in the previous period contains fine particles having a size of 20% to 500% of the thickness of the ink layer. The thermal transfer recording ink sheet according to claim 6, wherein the fine particles are inorganic fine particles. The thermal transfer recording ink sheet according to claim 6, wherein the fine particles are fine particles made of an organic polymer material. The amount of the inorganic fine particles added is 0.5 wt% to 120 wt% of a solid content excluding the fine particles added from the whole ink layer of the ink layer to which the fine particles are added. Item 8. The thermal transfer recording ink sheet according to Item 7. The addition amount of the fine particles of the organic polymer material is 0.1 wt% to 20 wt% of the solid content excluding the fine particles added from the whole ink layer of the ink layer to which the fine particles are added. The ink sheet for thermal transfer recording according to claim 8. The thermal diffusible dye-receiving layer of the thermal transfer recording image-receiving sheet contains a metal ion-containing compound, and the thermal diffusible dye contained in the ink layer of the thermal transfer recording ink sheet contains a metal ion-containing compound and a chelate complex. 6. The fog reduction method according to claim 1, wherein the fogging dye is a heat-diffusible dye that can be formed. The thermal diffusible dye-receiving layer of the thermal transfer recording image-receiving sheet contains a metal ion-containing compound, and the thermal diffusible dye contained in the ink layer of the thermal transfer recording ink sheet contains a metal ion-containing compound and a chelate complex. The thermal transfer recording ink sheet according to any one of claims 6 to 10, which is a heat-diffusible dye that can be formed.