JPS6063193A - Thermal transfer medium - Google Patents

Abstract

PURPOSE:To provide the titled medium capable of producing images with high density while consuming a minute amount of energy and capable of providing a uniform image density even in transferring multiple times, wherein a porous filler containing layer is provided between a plastic film base and a transfer layer consistuting a transfer sheet. CONSTITUTION:A layer containing a porous filler (e.g., silica) having an oil absorption of 50-300ml/100g is provided on a surface of the base consisting of a plastic film, and then a transfer layer comprising a leuco dye (preferably, crystal violet lactone) as a main constituent is provided thereon to obtain the transfer sheet. On the other hand, a receiving layer comprising a color developer for the leuco dye, preferably, 1-naphthol or the like, as a main constituent is provided on a base such as a paper and a synthetic paper to obtain a receiving sheet. The transfer sheet is combined with the receiving sheet to obtain the objective medium. It is preferable to incorporate a porous filler having an oil absorption of not less than 150ml/100g into the receiving layer.

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, the thermal transfer medium Y consists 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 from the back side of the sheet, or a heat-fusible transfer sheet. A combination of a transfer sheet and a receiving sheet is known, in which a transfer layer of a pigment or dye is provided on a support.The former uses a heat sublimable dye, so the receiving sheet 1
-The above dye image has poor storage stability and requires an overcoat on the transferred image, and the latter is a transfer layer with pigment or dye dispersed in a thermofusible material, so it is expensive. If a large amount of pigment is included for the purpose of obtaining a high-density image, the transfer efficiency will be low, making it difficult to obtain a high-density image.In addition, if a large amount of thermofusible material is used to further increase thermal sensitivity, Since a large amount of the thermofusible substance migrates to the receiving sheet side, when the transfer sheet and the receiving sheet 1- are peeled off, the separation does not occur smoothly, resulting in problems such as the thin line image area becoming unclear.

On the other hand, there is also known a thermal transfer medium 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.
This kind of thing is a one-reaction type, so when it comes to face-to-face contact,
If the transfer layer simply transfers to the receiving layer, a sufficient coloring reaction will not take place, resulting in a low-density image; however, if the heating conditions are set to higher temperature and longer thermal printing for the purpose of promoting sufficient reaction, Although the image on the receiving sheet becomes a higher-density image, there is a drawback in that the coloring reaction proceeds also on the transfer sheet, resulting in image formation.

〔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, there is provided a transfer sheet in which a transfer layer containing a leuco dye as a main component is provided on a support, and a receiving sheet in which a receiving layer in which a color developer for the leuco dye is provided as a main component on a support. A heat-sensitive transfer medium is provided, characterized in that the transfer layer is provided on the surface of a plastic film via a porous filler-containing layer having an oil absorption of 50 to 30,011 Q/LOOK.

In the thermal transfer medium of the present invention, a receiving sheet is stacked on a transfer sheet so that the receiving layer is in contact with the transfer layer of the transfer sheet, and the receiving sheet is placed on the back side of the transfer sheet or on the back side of the transfer sheet.

A desired colored image is formed on the surface of the receiving sheet by thermal printing from the back side of the receiving sheet, but in the present invention,
A plastic film is used as a support for the transfer sheet, and the surface of the plastic has an oil absorption of 50-3.
A porous filler-containing layer of 00m Q /100g (according to JIS K5101 method) is provided to provide an uneven shape and at the same time improve the ability to retain the leuco dye component, making it especially effective for multiple transfers. The leuco dye component can be smoothly transferred from the layer to the receiving layer.
Transfer images with uniform image density can be easily obtained.

In the present invention, as described above, a plastic film having a porous filler-containing layer on its surface is used as a support for the transfer layer, but in this case, the porous filler is
Use one with an oil absorption of 50 to 300 m n /100 g. If an oil absorption amount is less than 50mQ/100g, it is not preferable because the density of the obtained image will decrease greatly in multiple transfers.On the other hand, if an oil absorption amount is less than 30m
It is not preferable to use a material having a value larger than 0m Q/loog because the transfer efficiency will deteriorate and it will be difficult to obtain a high-density image. Specific examples of the porous filler used in the present invention include silica.

aluminum silicate, alumina, aluminum hydroxide,
Magnesium hydroxide, Ji! Examples include inorganic and organic fine powders such as formalin resin and styrene resin. In addition, in the porous filler-containing layer provided on the support, the proportion of the porous filler used is 0.5 to 1 M per 1 M of the support.
It is best to use a ratio of 2g.

There are various conventionally known plastic films used as supports, such as polyester films, polyamide films, polyvinyl chloride films,
There are polyethylene films, polypropylene films, etc. The formation of the porous filler-containing layer on the support can be performed using various binders as described below, and the proportion of the binder used is 1 to 1 part by weight of the porous filler in solid terms. The proportion is 10 parts by weight.

The transfer sheet used in the present invention is one in which a transfer layer containing a leuco dye as a main component is provided on the surface of a plastic film having a porous filler-containing layer on the surface as described above. In this case, any leuco dye that has been conventionally used for pressure-sensitive paper or thermal paper can be used.
Triphenylmethane-based, fluoran-based, 4-phenothiazine-based, auramine-based, and spiropyran-based ones are 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 lactone).

3.3-bis(ρ-dimethylaminophenyl)-6-dimethylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide.

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-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- (N-(3'-trifluoromethylphenyl)
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-dibutylamino-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, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane.

6'-bromo-3'-methoxy-benzoindo-
Pyrillospiran.

3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide, 37(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-47-chloro-5'
-methylphenyl)phthalide, In the present invention, the leuco dye is engraved on a support,
Usually 0.3~30g/m'', preferably 0.5~20
It is used at a rate of about g/m2.

The receptor sheet used in the present invention has a receptor layer containing a color developer for the leuco dye as a main component on a support such as synthetic paper or plastic film. In this case, as the color developer, an electron-accepting substance such as a phenolic substance, an organic acid or a salt or ester thereof is used, and from the viewpoint of practicality, one with a melting point of 200°C or less is preferably used. . 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-tert-butylphenol (98), 4-hydroxydiphenyl ether (84), 1-naphthol (
9B).

2-naphthol (121), methyl-4-hydroxybenzoate (131), 4-hydroxyacetophenone (109), 2,2'-dihydroxydiphenyl ether (79), 4-phenylphenol (166), 4
tert-octylcatechol (109), 2,2
'-dihydroxydiphenyl (103), 4,4'
-methylenebisphenol (160), 2,2'-methylenebis(4-chlorophenol)' (164), 2
,2'-methylenebis(4-methyl-6-tert-
butylphenol) (125), 4,4'-isopropylidene diphenol (156), 4,4'-isopropylidene bis(2-chlorophenol) (90),
4,4'-isopropylidene bis(2,6-dibromophenol) (172), 4,4'-isopropylidene bis(2-tert-butylphenol) (110)
, 4,4'-isopropylidene bis(2-methylphenol) (136), 4,4'-isopropylidene bis(2,6-dimethylphenol) (16 g), 4.4
'-5ec-butylidene diphenol (119), 4
．． 4'-5ea-butylidenebis(2-methylphenol) (142), 4,4'-cyclohexylidenediphenol (180]i, 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 (131), 4
-Hydroxybenzoic acid ethyl ester (116), 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 (111), 4-hydroxybenzoic acid cyclohexyl ester ( 119),
5-hydroxysalicylic acid (200), 5-chlorsalicylic acid (172), 3-chlorsalicylic acid (178),
Thiosalicylic acid (164), 2-chloro-5-nitrobenzoic acid (165).

4-methoxyphenol (53), 2-hydroxybenzyl alcohol (87), 2,5-dimethylphenol (75), benzoic acid (122), orthotoluic acid (1
07), metatoluic acid (111), para-ruylic acid (181), orthochlorobenzoic acid (142), metaoxybenzoic acid (200), 2,4-dihydroxyacetophenone (97), resorcinol monobenzoate (135), 4-hydroxybenzophenone (133
), 2,4-dihydroxybenzophenone (144),
2-naphthoic acid (184), 1-hydroxy-2-naphthoic acid (195), 3.4
-dihydroxybenzoic acid ethyl ester (128), 3
,4-dihydroxybenzoic acid phenyl ester (189
), 4-hydroxypropiophenone (150), salicyl salicylate (148), phthalic acid monobenzyl ester (107).

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 oil absorption amount is 50 m for the receptor layer.
It is preferable to contain a porous filler of Q / 100 g or more (according to JIS K 5101 method), preferably 150 m Q / 100 g or more. When contained in the receptor layer, the porous filler is 0.01 part by weight or more, usually 0.05 to IO parts by weight, preferably 0.1 to 3 parts by weight, per 1 part by weight of the color developer. range. 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.

Further, in the present invention, the transfer layer and, if necessary, the receiving layer have a melting point of 200° C. or lower, preferably 150° C.
Thermofusible substances having a melting point below .degree. C. can be added. The amount used is 0.1 to 50 parts by weight per 1 part by weight of Leuco mulberry.

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

(1) Fatty acid amides RlNHC:OR' (I) R4 R'' CON (II) \R8 (wherein R2 is an alkyl group having 1 to 30 carbon atoms, nL,
, R3 is an alkyl group having 10 to 30 carbon atoms, and R4 and RG 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 ace 1-amide, tridecyl propionamide, myristyl ace 1-amide, myristyl propionamide, pentadecyl acetamide, pentadecyl propion Amide, palmitylacetamide, palmitylpropionamide, palmitic acid amide, heptyl acetamide, heptyl propionamide, stearyl acetamide, stearyl propionamide, stearyl butyramide, stearyl valeramide, stearyl capronamide, stearyl lauramide, stearyl palmitin amide, stearyl Stearamide, nonadecylacetamide, nonadecylpropionamide, behenylacetamide, behenylpropionamide, behenylstearamide, undecanoic acid methylamide, undecanoic acid ethylamide, lauric acid methylamide, lauric acid ethylamide, tridecanoic acid methylamide, tridecanoic acid ethylamide, myristate methylamide , myristic acid ethylamide, pentadecanoic acid methylamide, pentadecanoic acid ethylamide, palmitic acid methylamide, palmitic acid dimethylamide, palmitic acid butyramide,
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) Aromatic carboxylic acid amides represented by the following general formula (m) (wherein R6 is an alkyl group having 1 to 3 carbon atoms, R?,
(R11 is hydrogen, halogen, lower alkyl group or lower alkoxy group, and n is 0 or l) Specific examples of such compounds include those shown below.

N-stearylbenzamide, N-palmityl-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 3 carbon atoms or a substituted or unsubstituted aryl group, R10 is hydrogen, halogen or a lower alkyl group) (wherein, R11 is an alkyl group having 1 to 30 carbon atoms, R12
is hydrogen, halogen or a lower alkyl group) Specific examples of such compounds include those shown below.

N-cyclohexyl acetamide, N-cyclohexylpropionamide, N-cyclohexylstearamide, 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-stearylhexahydrobenzamide.

(4) Phenyl esters of hydroxybenzoic acid represented by the following general formula (VI) (wherein X is halogen, an alkyl group or alkoxy group having 1 to 3 carbon atoms, halogen, substituted or unsubstituted aryl aralkyl group, substituted or unsubstituted aryloxy or aralkyloxy group, carboxylic acid group or hydroxyl group, n is 0,1°2 or 3, m is 1,2 or 3) such Specific examples of the compound 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 (2,4,6-1-
(lichlorophenyl) ester, salicylic acid (2-bromophenyl) ester, salicylic acid (4-bromophenyl) ester, salicylic acid (2,4-dibromophenyl) ester
Esters, salicylic acid (2,6-dibromophenyl) ester, salicylic acid (2,4,6-1-ribromophenyl) ester, salicylic acid (3-methylphenyl) ester, salicylic acid (2,4-dimethylphenyl) ester, salicylic acid (4 -tert-butylphenyl) ester, salicylic acid (4-tert-butylphenyl) ester, salicylic acid (2-methoxyphenyl) ester, salicylic acid (2-ethoxyphenyl) ester, salicylic acid (3-methoxyphenyl) ester, salicylic acid (4- hydroxyphenyl) ester, salicylic acid (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, 5-chlorosalicylic acid (3-methylphenyl) ester, 3,5-dichlorosalicylic acid (2-methoxyphenyl) ester.

(5) Benzoic acid phenyl esters represented by the following general formula (■) (wherein R is hydrogen, an alkyl group or alkoxy group having 1 to 3 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, R+4 is hydrogen, carbon number 1 to 3 o
an alkyl or alkoxy group, halogen, nitro group, nitrile group, acyloxy group, substituted or unsubstituted aryl or aralkyl group, substituted or unsubstituted aryloxy or aralkyloxy group or acyl group) Specific examples of the compound 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-chlor Phenyl ester, benzoic acid-3-bromphenyl ester, benzoic acid-4-nitrylphenyl ester, benzoic acid-2
, 4-dibromphenyl ester, benzoic acid-3-iodophenyl ester, benzoic acid-3-ditrophenyl ester, benzoic acid-4-methyl-2,6-dichlorophenyl ester, benzoic acid-4-isopropylphenyl ester ester, benzoic acid-4-t-butylphenyl ester,
Benzoic acid-4-benzylphenyl ester, benzoic 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-m-1-xybenzoic acid phenyl ester,
4-phenoxybenzoic acid phenyl ester, 4-acetoxybenzoic acid phenyl ester, 4-methoxybenzoic acid-4-methoxyphenyl ester, 2-ace1-xybenzoic acid phenyl ester, 2-benzoyloxybenzoic acid phenyl ester, 2- 21-Lobenzoic 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 (VII) (wherein R15 is hydrogen, an alkyl group or alkoxy group having 1 to 30 carbon atoms, or a halogen, and Rr6 is a carbon number of 1 to 30)
30 alkyl group, substituted or unsubstituted aryl or aralkyl group) Specific 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-benzoyl Oxybenzoic acid aenyl ester, 4-(4'-methylbenzoyloxy)benzoic acid ethyl ester, 4-(4'
-Me1-xybenzoyloxy)benzoic acid ethyl ester, 4-(4'-chlorobenzoyloxy)benzoic acid ethyl ester.

When providing a transfer layer and a receiving layer on each support, conventional binders are used, such as polyvinyl alcohol, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, polyacrylamide, and polyacrylic acid. ,
Water-soluble, organic solvent-soluble or aqueous emulsion-forming materials such as starch, gelatin, polystyrene, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, etc. can be used, but 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 , polyester, fluororesin, silicone resin, natural rubber, chlorinated rubber, butadiene rubber, olefin rubber, phenol resin, urea resin, melamine resin, epoxy resin, polyimide, etc. are preferably used as the binder. These resins are appropriately used in the form of homopolymers, copolymers, or mixtures of a plurality of resins, and it is particularly 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 be prepared using a solvent coating method,
Coating can be done by either a hot melt coating method or an aqueous emulsion coating method.

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

sp value ((Cal/cc)!'ri = (E/V)
"E...Cohesive energy density of resin (Cal/mol
e) ■...Molar volume of resin (cc/sole)
Furthermore, in the present invention, in order to obtain a transfer medium with higher thermal sensitivity, the transfer layer and/or the receiving layer containing the thermofusible material is formed by using the thermofusible material during or after the layer formation. It is advantageous to thermally melt the thermofusible substance once by applying heat treatment to a temperature higher than the melting point of
When forming a transfer layer containing a leuco dye, it is also a preferable means to use a coating liquid containing the leuco dye in a dissolved state.

Furthermore, the surface smoothness (Beckman smoothness, JIS-P8119) of the transfer layer and/or the receiving layer is 200 to 10.
It is also effective to adjust the time to 00 seconds.

The thermal transfer medium of the present invention is prepared by dispersing and dissolving the above-mentioned layer-forming components together with a solvent such as water using a pulverizing and mixing means such as a ball mill or an attritor to prepare a layer-forming liquid, which is then dried and adhered onto each support. Amount 0.3-30 g/r
It can be obtained by coating and drying to obtain Tr.

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, a suitable support surface such as paper 1 synthetic paper or plastic film can be placed on the surface of the non-image transfer layer of the transfer sheet described above, and a typewriter, iron pen, etc. It can be obtained by pressing the image-free transfer layer of the transfer sheet onto the surface of another suitable support in an image-like manner by pressing it in an image-like manner using a heat-suppressing means such as a thermal head or a thermal pen. .

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 transfer sheet 1- having a transfer layer with no image, the receiving layer of the receiving sheet is superimposed on the surface of the transfer layer of transfer sheet 1-, and transfer sheet 1 - This can be done by directly heating printing using a thermal printer from the back side of the transfer sheet, or by overlaying the receiving layer of the receiving sheet on the transfer layer side of the transfer sheet, and then printing black on the back side of the transfer sheet. This can be done by bringing the original drawing written in ink into close contact with each other, irradiating infrared rays from the side of the receiving sheet, and selectively heating only the black image area on the original drawing to a high temperature (in this case, the transfer sheet and It is necessary that the receiving sheet be transparent to infrared rays).

In thermal transfer as in the present invention, by repeating the above operations using the same transfer sheet,
Multiple copies can be easily obtained. Also, if you want to get multicolored copies.

If you create transfer sheets using leuco dyes of different tones as main coloring components, for example, create a transfer sheet with blue leuco dye and a transfer sheet with red leuco dye, and form a transferred image on the same receiving sheet by transfer. , 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 as 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., complete fixation is not achieved). It is also economical because high-density images can be obtained with a small amount of heating energy and many 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 layers of the receiving sheets 1 to 1 is uniform, and the dye transfer occurs little by little during transfer, so the image of the obtained copies is The concentration is uniform.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all percentages and parts shown in the following examples are based on weight.

Preparation of Example Support (1): Acrylic polyol 15 parts Polyisocyanate 5 Silica fine particles (oil absorption 160m Q /100g) 5
After dispersing the above composition in a ball mill for 24 hours, it was coated on the surface of a 12 μm polyester film and dried to obtain a support (1) with a coating weight of 1 g/rrr. .

Preparation of support (2): The oil absorption amount of the above silica fine particles is 200mQ/100g
A support (2) was obtained in the same manner except that it was made into a support (2).

Preparation of support (3): The above silica particles were mixed with urea-formalin resin (oil absorption m2
A support (3) was obtained in the same manner except that the support (3) was made to have a diameter of 00m'Q/loog).

Next, to create a heat-sensitive transfer sheet, 1 part crystal violet lactone 1 part carnauba wax 1 Q
! ! After dispersing liquid A consisting of ethyl cellulose 5/I water 75n using a ball mill for 24 hours, using a wire bar, the above supports (1), (2) and (
3) After coating and drying each surface, the amount of adhesion is Log/mF.
Transfer sheets (A), (B) and (C) were created.

Next, in order to create a receiving sheet, 20 parts of 4-hydroxybenzoic acid n-butyl ester, silica fine particles (oil absorption: 200 m Q /100 g) 1
A composition consisting of 0 n polyvinyl alcohol 3++ + 1 oool/water was dispersed for 24 hours using a ball mill, and then applied to the surface of high-quality paper (35 g/rr?) using a wire bar and dried to form a receiving sheet with a coating weight of 5 g/m. Created.

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.

A transfer sheet (D) for comparison was created.

Comparative Example 2 Silica fine particles of Example 1 (oil absorption amount 20Qm Q/1
A comparative transfer sheet (E) was prepared in the same manner except that the transfer sheet (00g) had an oil absorption of 10mD, /100g.

Transfer sheet 1- (A) (B) obtained as above
The coated surfaces of (C), (D), and (E) were brought into contact with the receiving sheet, and thermal transfer was performed by applying 1 mj of heating energy to the back surface of the transfer sheet using a thermal head.

Table 1 shows the density (measured using a Macbeth densitometer) of the obtained transferred colored image. Next, the same transfer sheet (Δ')
CB) (C) (D) (E) were used to perform repeated transfers, and the color image density of the resulting copies is shown in Table 1.
Shown below. From the results shown in Table 1, it can be seen that Transfer Sheets 1 to 1 of the present invention provide higher and more uniform image densities than those of the comparative examples.

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, A heat-sensitive transfer medium characterized in that the transfer layer is provided on the surface of a plastic film via a porous filler-containing layer having an oil absorption of 50 to 300 mQ/100g.