JPS6013594A - Thermal transfer medium - Google Patents

Abstract

PURPOSE:To provide a thermal transfer medium capable of transferring a high- density stable image with a minute amount of energy, which comprises a transfer sheet provided with a transfer sheet on a base having a specified surface roughness and a receiving sheet provided with a receiving layer on a base. CONSTITUTION:The transfer sheet comprising 0.3-30g/m<2> of a leuco dye and a binder, e.g., PVA, is provided on a base provided with minute rugged patterns to have a surface roughness of 0.5-3mum by embossing, sand blasting, chemical treatment or the like to obtain the transfer sheet. On the other hand, the receiving layer comprising a color developer having a melting point of not higher than 200 deg.C, e.g., 4-t-butylphenol, a porous filler having an oil absorption of not lower than 50ml/100g, e.g., silica, a heat-fusible substance having a melting point of not higher than 200 deg.C, e.g., decylacetamide, and a binder is provided on a base to obtain the receiving sheet. The transfer sheet and the receiving sheet are laminated on each other so that the transfer layer and the receiving layer make contact with each other, thereby obtaining a thermal transfer medium.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a thermal transfer medium that utilizes a color reaction between a leuco dye and a color developer. Furthermore, the present invention relates to a thermal transfer medium that provides a transferred image with uniform density even after multiple transfers.

[Prior art]

Conventionally, heat-sensitive transfer media include those consisting of a transfer sheet in which a heat-sublimable dye is provided on a support and a receiving sheet that receives a heat-sublimable dye image by thermal printing on the back surface of the sheet, and heat-fusible media. A combination of a transfer sheet I-, in which a transfer layer of a pigment or dye is provided on a support, and a receiving sheet is known. The image has poor shelf life, requires an oat<- coat to be applied on the transferred image, and the latter (
Well, a pigment or dye dispersed in a thermofusible substance.

Since it is ear dust, if a large amount of pigment is included in the eye 1'1'-J where a high-density image is to be obtained, the transfer efficiency will be lowered, and as a result, it will be difficult to obtain a high-density image, and the thermal sensitivity will further increase. Therefore, if a large amount of thermofusible material is used, a large amount of thermofusible material will transfer to the receiving sheet side, so when peeling the transfer sheet and receiving sheet, it may be difficult to There were drawbacks such as not being peeled off and image areas of fine lines becoming unclear.

On the other hand, there are also known thermal transfer media in which substances that react with each other to form a color due to heat are supported on separate supports, and these support layers are brought into mutually facing contact to perform thermal printing. Since the material is of a reactive type, when the transfer layer simply transfers to the receiving layer during face-to-face contact, a sufficient coloring reaction does not take place, resulting in a low-density image.In order to promote a sufficient reaction, If the heating conditions are higher and thermal printing is performed for a longer period of time, the image on the receiving sheet will be a higher density image, but the drawback is that the coloring reaction will proceed on the transfer sheet as well, resulting in the formation of one image. .

〔the purpose〕

The present invention provides a stable transfer image with high density by using a small amount of thermal energy, and also provides a uniform image density even after multiple transfers by transferring a small amount of leuco dye component from the transfer layer to the receiving layer. The purpose is to provide a thermal transfer medium.

〔composition〕

According to the present invention, a transfer sheet having a transfer layer containing a leuco dye as a main component is provided on a support, and a receiving layer containing a color developer as a main component for imprinting on the leuco dye is provided on a support. The transfer layer consists of a receiving sheet.

A thermal transfer medium is provided, characterized in that it is provided on a support surface having fine irregularities with a surface roughness of 0.5 to 3 μm.

The thermal transfer medium of the present invention is produced by stacking a receiving sheet on a transfer sheet so that its receiving layer is in contact with the transfer layer of transfer sheet 1-, and receiving thermal printing from the back side of transfer sheet 1- or from the back side of the receiving sheet. A desired colored image is formed on the surface of the sheet, but in the case of wood-based lubricants, the adhesion area is increased by giving the surface of the support of the transfer sheet a fine uneven shape, and even after multiple transfers. The leuco dye component transfers smoothly from the transfer layer to the receiving layer.
A transferred image with uniform image density can be obtained.

The formation of fine irregularities can be achieved by treating the support with an embossing method, a sandblasting method, a chemical treatment method, a pigment addition method, a pigment coating method, or the like.

The embossing method is a method in which a roll having minute irregularities is heated and pressed with a pressure roll to give the film surface irregularities.The sandblasting method is a method in which carborundum or metal particles are added to the film together with compressed air. This is a method in which the surface of the film is strongly sprayed to create irregularities.The chemical treatment method is a method in which the film is immersed in a concentrated solution of acid or alkali to slightly erode the film surface and create irregularities. The pigment addition method is a method in which fine powder of a colorless or colored pigment is blended into a thermoplastic resin to create a film with unevenness during the manufacturing stage of the plastic film. In the pigment coating method, the pigment used in the pigment addition method is coated on the film surface together with a binder resin.

In particular, in the process of manufacturing plastic films (or sheets), fine powders (particle size 0.5 to 1 μm), a plastic film (or Sea 1-) having a fine unevenness function can be easily obtained.

In the present invention, the fine irregularities provided on the surface of the support are
In the case of the present invention, the surface roughness (Rz) is set to 0.5 to 3μ, since it affects the transferred image density and the number of repeated transfers.
It has been confirmed that this method gives favorable results when specified in m. In addition, in this specification, 1) surface roughness (Itz) is J
IS-B-0601). When the surface roughness l1z) is 0.5 μm or less, the image density becomes high but the number of repeated transfers decreases, while when it is 3 μrn or more, the single image density decreases but the number of transfers increases. The uneven shape of the surface of the support is 0.5 μm to 1
．． The surface roughness is preferably about 5 μm.

The transfer sheet used in the present invention is one in which a transfer layer containing a dileuco dye as a main component is provided on the surface of a support having fine irregularities on the surface as described above. In this case, the leuco dyes that have traditionally been used for pressure-sensitive paper and thermal paper can also be used, including triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based leuco dyes. is preferably applied. Specific examples of these leuco dyes are shown below. 3,3-bis(P-dimethylaminophenyl)-phthalide, 3.3
-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet rough 1-
3.3-bis(p-dimethylaminophenyl)-6-diethylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorphthalide, 3.3-bis(p-dibutylaminophenyl) Phthalide, 3-cyclohexylamino-6-chlorofluoran.

3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ditylamino)-6-methyl-7-anilinofluorane.

3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-1-lifluoromethylphenyl)amino)-6-dinithylaminofluorane, 2-(
3,6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7-(0 -chloroanilino)fluoran, 3-diethylamino-7-(0-chloroanilino)fluoran, 3-N-methyl-N-amylamino-6-methyl-7-
Anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N,N- diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran, Benzoyl Leukomethi [Non-blue.

6'-Chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3- (2'-methoxy-5'-chlorophenyl) phthalide, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl) phthalide, 3 -(2'-hydroxy-4'-diethylaminophenyl)-: 3-(2'-methoxy-5'-methylphenyl)phthalide, 3-(2'-methoxy-4'-dimethylaminophenyl)-3 -(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthari 19 In the present invention, the leuco dye is applied to the support.
Usually 0.3~30g/m'', preferably 0.5~20
It is used at a rate similar to that of Barn'.

The receptor sheet used in the present invention is one in which a receptor layer containing a color developer for the leuco dye as a main component is provided on a support such as paper, synthetic paper, or plastic film. In this case, as a color developer, an electron-accepting substance such as a phenolic substance, an organic acid or a salt thereof, or nisol is used, and from the viewpoint of practicality, one with a melting point of 200°C or less is preferably used. be done. Specific examples of color developers preferably applied in the present invention are shown below. Note that the numbers in parentheses indicate the melting point.

4-Ser L-butylphenol (98), 4-hydroxydiphenyl ether (84), ■-naphthol (
98), 2-naphthol (121), methyl-4 dihydroxybenzoate (1,31), 4-hydroxyacetophenone (109), 2,2'-dihydroxydiphenyl ether (79), 4-phenylphenol (1
66), 4-SerL-octylcatechol (109)
, 2,2'-dihydroxydiphenyl (103), 4
, 4'-methylenebisphenol (160), 2,2
'-methylenebis(4-chlorophenol) (164
), 2,2'-methylenebis(4-methyl-6-t
, er sheeptylphenol) (125), 4,4'
-isopropylidenediphenol (156), 4,4'
-isopropylidene bis(2-chlorophenol) (
90), 4,47-isopropylidene bis(2,6-dibromophenol) (172), 4,4'-isopropylidene bis(2-Ler monobutylphenol) (1
10), 4,4'-isopropylidene bis(2-methylphenol) (136), 4,4'-isopropylidene bis(2,6-dimethylphenol) (168), 4
．． 4'-5ec-butylidene diphenol (119)
, 4,4'-5ec-butylidenebis(2-methylphenol) (142), 4,4'-cyclohexylidenediphenol (180), 4,4'-cyclohexylidenebis(2-methylphenol) (184) , salicylic acid (163), salicylic acid methalyl ester (7
4), salicylic acid phenacyl ester (110), 4-
Hydroxybenzoic acid methyl ester (13), ]4
-Hydroxybenzoic acid ethyl ester 11.6), 4-
Hydroxybenzoic acid propyl ester (98), 4-hydroxybenzoic acid isopropyl ester (86), 4-
Hydroxybenzoic acid butyl ester (71), 4-hydroxybenzoic acid isoamyl ester (50), 4-hydroxybenzoic acid phenyl ester (178), 4-hydroxybenzoic acid benzyl ester (1,11), 4-hydroxybenzoic acid cyclohexyl ester Esther (119),
5-hydroxysalicylic acid (200), 5-chlorsalicylic acid (172), 3-chlorsalicylic acid (178),
Thiosalicylic acid (164), 2-chloro-5-21-lobenzoic acid (165), 4-methoxyphenol (53)
, 2-hydroxybenzyl alcohol (87), 2,5
-dimethylphenol (75), benzoic acid (122),
Ortho-1-ruylic acid (1,07), meta-1helyl 11
(111), para-toluic acid (181), ormyfurobenzoic acid (142), metaoxybenzoic acid (200)
, 2,4-dihydroxyacetophenone (97), resorcinol monobenzony 14 (135), 4-hydroxybenzophenone (], 33), 2,4-dihydroxybenzophenone (1/14), 2-nano 1-ic. acid (]84), 1-hydroxy-2-naphthoic acid (195), 3,4-dihydroxybenzoic acid ethyl ester (128), 3,4-dihydroxybenzoic acid phenyl ester (189), 4-hydroxypropio Phenone (150), salicyl salicile h (
148), phthalic acid monobenzyl ester (407).

Further, in the present invention, a phenolic compound represented by the general formula (wherein R is an alkylene group containing 1 to 5 ether bonds) can be used as a color developer. This phenolic substance can be easily produced in high yield and purity by reacting monothiohydroquinone with the corresponding dihalogenoalkyl ether under alkaline conditions.
Moreover, it can be synthesized relatively inexpensively.

In the phenolic substance represented by the above general formula, R
is an alkylene group containing 1 to 5 ether groups; in this case, the ether group may be present in the main chain of the alkylene group or may be present in the side chain. The number of carbon atoms contained in this ether group-containing alkylene group is usually in the range of 2 to 15. Preferred ether group-containing alkylene groups are:
It contains 1 to 3 ether bonds and has 2 to 7 carbon atoms.

In the present invention, the receiving layer and/or the transfer layer has an oil absorption amount of 50 m Q / 100 g (JIS K
5101 method) or more preferably L50 m Q /
Preferably, it contains 100 g or more of porous filler. The porous filler to be contained in the receptor layer is 0.01 part by weight or more, usually 0.01 part by weight or more, per 1 part by weight of the color developer.
The amount ranges from 0.05 to 10 parts by weight, preferably from 0.1 to 3 parts by weight. The proportion of the porous filler contained in the transfer layer is 0.01 to 1 ffiff per 1 part by weight of the leuco dye.
i part, preferably 0.03 to 0.5 part by weight. Specific examples of porous fillers include inorganic and organic fine powders such as silica, aluminum silicate, alumina, aluminum hydroxide, magnesium hydroxide, urea-formalin resin, and styrene resin.

In addition, in the present invention, the transfer layer and, if necessary, the receiving layer have a melting point of 200° C. or lower, preferably 15° C.
Thermofusible substances having a melting point below 0° C. can be added. The amount used is 0.1 to 50 parts by weight per 1 part by weight of the leuco dye.

The thermofusible substances preferably used in the present invention are as follows.

(1) Fatty acid amides R'NHCOR'' represented by the following general formula (I) or (II) Alkyl group, R1,
R3 is an alkyl group having 10 to 30 carbon atoms, and R4 and os are hydrogen or a lower alkyl group.) Specific examples of such fatty acid amides include the following.

decyl acetamide, decyl propionamide, undecyl acetamide, undecyl propionamide, lauryl acetamide, lauryl propionamide, tridecyl acetamide, tridecyl propionamide, myristyl acetamide, myristyl propionamide,
Pentadecyl acetamide, pentadecyl propionamide, palmitylacetamide, palmitylpropionamide, palmitylbutyramide, heptylace1-amide, heptylpropionamide, stearyl acetamide, stearylpropionamide, stearylbutyramide, stearylvaleramide, stearylcapronamide , stearyllaurinamide, stearylpalmitinamide, stearylstearamide, nonadecylace1-amide, nonadecylpropionamide, behenylacetamide, behenylpropionamide, behenylstearamide, undecanoic acid methylamide, undecanoic acid ethylamide, lauric acid methylamide, lauric acid ethylamide, Tridecanoic acid methylamide.

1-Rysocanoic acid ethylamide, myristic acid methylamide, myristic acid ethylamide, pentadecanoic acid methylamide, pentadecanoic acid ethylamide, palmitic acid methylamide, palmitic acid dimethylamide, palmitic acid butylamide, stearic acid methylamide, stearic acid ethylamide.

Stearic acid propylamide, stearic acid butylamide, stearic acid dimethylamide, stearic acid diethylamide, stearic acid dibutylamide, nonadecanoic acid methylamide, nonadecanoic acid ethylamide, behenic acid methylamide, oleic acid methylamide, oleic acid ethylamide (2) The following general formula (III Aromatic carboxylic acid amides represented by (wherein 1 (6 is an alkyl group having 1 to 30 carbon atoms, R7,
(R9 is hydrogen, halogen, lower alkyl group or lower alkoxy group, and n is O or 1) Specific examples of such compounds include those shown below.

N-stearylbenzamide, N-no(lumityl-2-
Chloropenzamide, N-stearyl-2-methoxybenzamide, N-stearyl-4-methylbenzamide, N-palmityl-2,4-dimethylbenzamide, N
-Behenylbenzamide, N-behenyl-2-methylbenzamide, N-stearylphenylacetylamide,
N-Behenylphenylacetylamide.

(3) Amides having a cyclohexyl ring represented by the following general formulas (IV) and (V) (wherein R9 is an alkyl group having 1 to 30 carbon atoms or a substituted or unsubstituted aryl group, R is hydrogen, norogen or a lower alkyl group) (wherein R is an alkyl group having 1 to 30 carbon atoms, tt12
is hydrogen, halogen or a lower alkyl group) Specific examples of such compounds include those shown below.

N-cyclohexyl acetamide, N-cyclohexylpropionamide, N-cyclohexyl stearamide, N-cyclohexylbenzamide, N-cyclohexyl-2-methylbenzamide, N-cyclohexyl-2- Chlorobenzamide, N-cyclohexyl-2,
4-dimethylbenzamide, N-cyclohexylpalmitic acid amide, N-(chlorohexyl) palmitic acid amide, N-(2-methylcyclohexyl) stearic acid amide, N-stearylhexahydropenzamide.

(4) Phenyl esters of hydroxybenzoic acid represented by the following general formula (VI) (wherein, group, substituted or unsubstituted aryloxy or aralkyloxy group, carboxylic acid group or hydroxyl group, where n is 0,1°2 or 3 and 1m is 1,2 or 3) Specific examples of such compounds Examples include those shown below.

4-Hydroxybenzoic acid phenyl ester, 4-hydroxybenzoic acid (2-methoxyphenyl) ester, 4-
Hydroxybenzoic acid (2-methoxy-4-methylphenyl) ester, 4-hydroxybenzoic acid (3,5-dioxyphenyl) ester, 3-hydroxybenzoic acid (4
-carboxyphenyl) ester, 4-hydroxybenzoic acid (4-butoxyphenyl) ester, 4-hydroxybenzoic acid (4-chlorophenyl) ester, salicylic acid (2-chlorophenyl) ester, salicylic acid (4-
chlorophenyl) ester, salicylic acid (2,3-dichlorophenyl) ester, salicylic acid (2,6-dichlorophenyl) ester, salicylic acid (2,4,6-trichlorophenyl) ester, salicylic acid (2-bromophenyl) ester, salicylic acid (4- bromophenyl)
Esters, salicylic acid (2,4-dibromophenyl) ester, salicylic acid (2,6-dibromophenyl) ester, salicylic acid (2,4,6-)-dibromophenyl) ester, salicylic acid (3-methylphenyl) ester, salicylic acid ( 2,4-dimethylphenyl) ester, salicylic acid (4-tert-butylphenyl) ester, salicylic acid (4-tert-aryamylphenyl) ester, salicylic acid (2-methoxyphenyl) ester,
Salicylic acid (2-ethoxyphenyl) ester, salicylic acid (3-methoxyphenyl) ester, salicylic acid (
4-hydroxyphenyl) ester, salicyl #(4-
benzylphenyl) ester, salicylic acid (4-benzoylphenyl) ester, salicylic acid (2-methoxy-
4-allylphenyl) ester, salicylic acid (alpha naphthyl) ester, salicylic acid (beta naphthyl) ester, salicylic acid (4-chloro-3-methylphenyl) ester, salicylic acid (3-hydroxyphenyl) ester, salicylic acid (4-propenylphenyl) ester ester, 5-chlorosalicylic acid (3-methylphenyl) ester, 3,5-dichlorosalicylic acid (2-methoxyphenyl) ester.

(5) Benzoic acid phenyl esters represented by the following general formula (VII) (wherein RlB is hydrogen, an alkyl group or alkoxy group having 1 to 30 carbon atoms, a halogen, a nitro group, a nitrile group, an acyloxy group, a substituted or unsubstituted aryl or aralkyl group, substituted or unsubstituted aryloxy or aralkyloxy group, R14 is hydrogen, carbon number 1-
30 alkyl or alkoxy groups, halogens, di-1-lo groups, nitrile groups, acyloxy groups, substituted or unsubstituted aryl or aralkyl groups, substituted or unsubstituted aryloxy or aralkyloxy groups, or acyl groups. ) Specific examples of such compounds include those shown below.

Benzoic acid phenyl ester, benzoic acid-4-methylphenyl ester, benzoic acid-2,4-dichlorophenyl ester, benzoic acid-2,4,6-trichlorophenyl ester, benzoic acid-2-methyl-4-chlorophenyl ester ester, benzoic acid-3-bromphenyl ester, benzoic acid-4-nitrylphenyl ester, Andara C aromatic acid-2
, 4-dibromophenyl ester, benzoic acid-3-iodophenyl ester, benzoic acid-3-diI-phenyl ester, benzoic acid-4-methyl-2,6-cyclophenyl ester, benzoic acid-4 -isopropylphenyl ester, benzoic acid-4-tert-butylphenyl ester, benzoic acid-4-benzylphenyl ester, branch, fragrant acid-4-(1-naphthyl)phenyl ester, benzoic acid-2-benzoyloxyphenyl ester, Benzoic acid-
4-(2-methyl)diphenyl ester, benzoic acid-2
-Phenylethyloxyphenyl ester, benzoic acid-
2-acetoxyphenyl ester, benzoic acid-4-methoxyphenyl ester, benzoic acid-4-(4-methyl)
Phenoxyphenyl ester, 4-methylbenzoic acid phenyl ester, 4-methoxybenzoic acid phenyl ester, 4-buenoxybenzoic acid phenyl ester, 4-acetoxybenzoic acid phenyl ester, 4-methoxybenzoic acid-4-methoxyphenyl ester, 2 -acetoxybenzoic acid phenyl ester, 2-benzoyloxybenzoic acid phenyl ester, 2-nitrobenzoic acid-4-methylphenyl ester, 4-nitrobenzoic acid-4-methylphenyl ester, 4-benzoyloxybenzophenone, 2- Benzoyloxy-4-methylbenzophenone.

(6) Benzoyloxybenzoic acid esters represented by the following general formula (VIII) (wherein R1' is hydrogen, an alkyl group or alkoxy group having 1 to 30 carbon atoms, or halogen, and R is 1 to 30 carbon atoms)
Examples of such compounds include those shown below.

4-benzoyloxybenzoic acid methyl ester, 4-benzoyloxybenzoic acid ethyl ester, 4-benzoyloxybenzoic acid-n-propyl ester, 4-benzoyloxybenzoic acid benzyl ester, 4-benzoyloxybenzoic acid phenyl ester, 2- Benzoyloxybenzoic acid aenyl ester, 4-(4'-methylbenzoyloxy)benzoic acid ethyl ester, 4-(4'
-methoxybenzoyloxy)benzoic acid ethyl ester, 4-C4'-chlorobenzoyloxy)benzoic acid ethyl ester.

When a transfer layer and a receiving layer are provided on each support, conventional binders are used, such as polyvinyl alcohol, meth-1-xycellulose, human U-xyedylcellulose, carboxymethylcellulose, and polyvinylpyrrolidone. , polyacrylamide, polyacrylic acid, starch, gelatin, polystyrene, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate-1, etc., which are water-soluble, organic solvent-soluble, or capable of forming an aqueous emulsion. However, especially in the case of the transfer layer, resins having a melting point or softening point of 50 to 130°C, such as polyethylene, polypropylene, polystyrene,
Petroleum resin, acrylic resin, vinyl chloride resin, vinyl acetate resin, vinylidene chloride resin, polyvinyl alcohol, cellulose resin, polyamide, polyacetal, polycarbonate, boron diester, fluororesin, silicone resin, natural rubber, chlorinated rubber, It is preferable to use butadiene rubber, olefin rubber, phenol resin, urea resin, melamine resin, epoxy resin, polyimide, etc. as the binder. These resins are suitably used in the form of homopolymers, copolymers, or mixtures of a plurality of resins, and in particular,
It is preferable to use those having an sp value (solubility parameter) of 8 or more, preferably 9 or more. When creating a transfer sheet using these resins as a binder, the transfer forming liquid can also be applied by b) deviation of a solvent coating method, a hot melt coating method, or an aqueous emulsion coating method.

Note that the sp value indicates the solubility parameter τ of the resin, and is expressed by the following formula.

5. Value [(.8□/..)”) = (□/v >hE・・
・Cohesive energy density of resin (Cat/mole)v
--- Molar volume of resin (cc/mole) Furthermore, in the present invention, in order to obtain a transfer medium with higher thermal sensitivity,
The transfer layer and/or receptor layer containing the thermofusible substance are
During or after layer formation, it is advantageous to perform heat treatment to a temperature higher than the melting point of the thermofusible substance to heat-melt the thermofusible substance once, and furthermore, to apply a transfer layer containing a leuco dye. When forming, it is also a preferable means to use a coating liquid containing a leuco dye in a dissolved state.

Furthermore, the surface flatness of the transfer layer and/or the receiving layer (Beckman smoothness, JIS-P8119) is 200 to 1.
It is also effective to adjust the time to 000 seconds.

In the thermal transfer medium of the present invention, each layer forming liquid is prepared by dispersing and dissolving the above-mentioned layer forming components together with a solvent such as wood using a pulverizing and mixing means such as a ball mill or attritor, and this is dried and adhered onto each support. It can be obtained by coating and drying so that the amount is 0.3 to 30 g/m.

In the transfer sheet used in the present invention, the transfer layer provided on the surface thereof may be a so-called plain (no image) layer provided uniformly over the entire surface of the support, or may be formed in advance into a desired image form. It may be provided.

A transfer sheet with a non-image transfer layer has a layer on the surface of the support.
It can be obtained by simply applying a transfer layer forming liquid. On the other hand, those having an image-like transfer layer can be obtained by applying a transfer layer forming liquid onto the surface of a support in the form of a desired image (including letters) by letterpress printing or gravure printing. Alternatively, paper, synthetic paper,
Appropriate supports such as plastic films are stacked one on top of the other, and pressed in an image form from the support side or the transfer sheet 1 side using a suppressing means such as a typewriter or iron pen, or a heating suppressing means such as a thermal head or a thermal pen. can be obtained by imagewise depositing the imageless transfer layer of the transfer sheet onto the surface of another suitable support.

To carry out the thermal transfer of the present invention, for example, when using a transfer sheet having an image-shaped transfer layer, a receiving sheet is placed on the surface of the transfer layer so that the receiving layer is in contact with the surface of the transfer layer, and then this is rolled with a heating roll. On the other hand, when using a transfer sheet with a transfer layer without an image, the receiving layer of receiving sheet 1- is overlaid on the transfer layer surface of the transfer sheet, and , can be done by direct heating printing using a thermal printer,
Alternatively, the receiving layer of the receiving sticker l- is placed on the transfer layer surface of the transfer sheet, and an original drawing written in black ink is brought into close contact with the back surface of the transfer sheet, and infrared rays are irradiated from the side of the receiving sheet surface. This can be done by selectively heating only the black areas of the original image to a high temperature (in this case, both the transfer sheet and the receiving sheet must be transparent to infrared rays). ).

In thermal transfer as in the present invention, by repeating the above steps using the same transfer sheet,
Multiple copies can be easily obtained. In addition, when obtaining multicolor copies, create transfer sheets with leuco dyes of different tones as the main coloring components, for example, create a transfer sheet with blue leuco dye and a transfer sheet with red leuco dye, and create the same transfer sheet. If a transfer image is formed by transfer onto a receiving sheet, blue and red colored images can be formed on the same sheet.

〔effect〕

In the present invention, since the leuco dye and its color developer are contained on separate supports, there is no problem of color fogging during production or storage, which was seen with conventional thermal paper. Furthermore, since the resulting copy contains only a color developer and no leuco dye in the non-image area, no color development occurs even if it is heated (i.e., it is completely fixed). (It is a sexual thing). It is also economical because high-density colorimetry can be obtained with a small amount of heating energy, and a large number of copies can be made using the same transfer sheet. Moreover, in the copies obtained in this case, the transfer of the leuco dye from the transfer layer of the transfer sheet to the receiving layer of the receiving sheet is uniform, and the dye transfer occurs little by little during transfer, so the image density of the obtained copies is low. It is homogenized.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that "1 part" and "%" shown below are both based on weight.

Example 1 Acrylic polyol 15 parts Polyisocyanate 5 n Silica fine particles (average particle size 0.5 to 1 μm) 5 n Methyl ethyl ketone 7517 After dispersing the above composition in a ball mill for 24 hours, a 12 μm polyester film was dispersed using a wire bar. The coating was applied to the surface and dried to obtain a roughened support with a surface roughness of 1 μm.

Next, to create a heat-sensitive transfer sheet, crystal violet lactone 10 parts carnauba wax 1Qt
After dispersing solution A consisting of t ethyl cellulose 5 u water 75 n for 24 hours using a ball mill, it was applied to the surface of the roughened support using a wire bar and dried to transfer the adhesion amount], Og/rrr. Sea I・(A
)It was created.

Next, in order to create a receiving sheet, 20 parts of r1-butyl 4-hydroxybenzoate ester silica fine particles (oil absorption 200 m Q / 100 g
) 10n polyvinyl alcohol water ], 00! The composition consisting of + was dispersed for 24 hours using a ball mill, and then applied and dried using a wire bar on the surface of high-quality paper (35 g/m') to prepare a receiving sheet with an adhesion weight of 5 g/rr.

Example 2 A polyester film with a thickness of 12 μm was immersed in a 5% trickle acetic acid solution for 5 minutes, and after washing with water, the surface roughness was 2.5 μm.
A support with a roughened surface was obtained.

Next, a transfer sheet (B) was prepared in the same manner as in Example 1 except for using the above support.

Comparative Example 1 The above liquid A was applied to the surface of the 12 μm thick unroughened polyester film of Example 1 in the same manner as in Example 1 to create a comparative transfer sheet (C).

Comparative Example 2 In Example 1, when roughening the support, instead of using silica fine particles (0.5 to 1 μm), particles with an average particle size of about 5 μm were used.
A comparative transfer sheet (D) was prepared in the same manner except that a support having a surface roughness of 5 μm formed using the same material as that of Example 1 was used.

Transfer sheets obtained as above (A) (B) (C
) (D) was brought into contact with the receiving sheet I and the coated surface, and a thermal head was used to apply 1 mj on the back side of the transfer sheet.
Thermal transfer was performed by applying heating energy of . Table 1 shows the density (measured using a Macbeth densitometer) of the obtained transferred colored image. The following identical transfer sheets (A) (B) (C
) (o) was used to perform repeated transfers, and the color image densities of the copies obtained at that time are shown in Table 1.

From the results shown in Table 1, the transfer sheet of the present invention has
It can be seen that a higher and more uniform image density can be provided than that of the comparative example.

Table-1

Claims (1)

[Claims] (1) consisting of a transfer sheet provided on a support with a transfer layer containing a leuco dye as a main component, and a receiving sheet provided on a support with a receiving layer containing a color developer for the leuco dye as a main component, Thermal transfer medium 1 characterized in that the transfer layer is provided on the surface of a support having fine irregularities with a surface roughness of 0.5 to 3 μm.