JPS61114883A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To contrive better gradation expression of image density, by a method wherein a transfer layer comprising a leuco dye is provided on a base, and a heat-fusible substance having a melting point lower than that of the dye is provided thereon. CONSTITUTION:When a receiving sheet comprising a color developer layer is laid on the thermal transfer sheet and thermal printing is conducted, the heat-fusible substance having a lower melting point and constituting an upper layer of the transfer layer is first melted, then the leuco dye having a higher melting point and constituting a lower layer of the transfer layer is co-melted with the substance in an amount proportional to the amount of the substance melted, and the co-melted material is transferred to a receiving layer, where it is co-melted with a color developer, thereby forming a developed color image on the receiving sheet. Since the heat-fusible substance has a high melt viscosity, the melted material of the transfer layer is not flowingly transferred to the receiving layer in a single stroke, and when thermal energy is increased, the viscosity of the melted material is lowered, and the amount of the co-melted material transferred by flowing to the receiving layer is correspondingly increased. Accordingly, the color development quantity can be controlled by regulating the thermal energy, resulting in that a developed color image with gradated density corresponding to the thermal energy is formed on the receiving sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thermal transfer sheet containing a leuco dye used in combination with a receiving sheet having a color developer layer.

[Prior art]

Conventionally, thermal transfer methods have used a transfer sheet in which a heat-sublimable dye is provided on a support, or a transfer sheet in which a heat-fusible substance and a pigment are provided on a support, and a receptor sheet is placed on top of this. A method of forming a transfer image on a receiving sheet by thermal printing is known. However, when using a transfer sheet in which a heat sublimable dye is provided on a support, although it has excellent gradation expression of one image density, it has the drawbacks of low heat sensitivity and poor storage stability. In the case of a heat-sensitive transfer sheet in which a heat-fusible substance and a pigment are provided on a support, the sheet has excellent heat sensitivity and storage stability, but has the drawback of not being able to express gradation at a single image density.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive transfer sheet that has excellent thermal sensitivity and storage stability, as well as excellent gradation expression of image density.

〔composition〕

According to the present invention, a transfer layer containing a leuco dye is provided on a support, and a layer of a thermofusible substance that melts at a lower temperature than that of the leuco dye is provided thereon. A thermal transfer sheet used in combination with a receptor sheet having a colorant layer is prepared.

The thermal transfer sheet 1- of the present invention has a transfer layer containing a leuco dye provided on a support, and a thermofusible substance that melts at a lower temperature than the leuco dye provided on the transfer layer.

According to the research conducted by the present inventors, such a heat-sensitive transfer sheet can be produced by overlapping a receptor sheet having a color developer layer, heating printing from the back side of the heat-sensitive transfer sheet, and transferring the heat-fusible substance and the heat-fusible substance on the heat-sensitive transfer sheet. It has been found that a colored image with gradation can be obtained when a leuco dye and a color developer on a receiving sheet undergo a eutectic reaction. That is, when both sheets are overlapped and printed by heating, first the low-temperature-melting thermofusible substance forming the upper layer of the transfer layer melts, and then the high-temperature melting leuco dye forming the lower layer melts. Eutectic melts in proportion to the amount of melting of the thermofusible substance,
Transfers to the receptor layer (developer layer). When the eutectic material is transferred to the receiving layer, it is further eutecticized with the color developer to form a colored image on the receiving sheet. In this case, the
Because the heat-fusible substances used in the transfer layer have high melt viscosity, the melt in the transfer layer does not transfer fluidly to the receiving layer all at once, but transfers little by little, and when the heating energy is increased, the viscosity of the melt decreases. The amount of flow transfer of the eutectic to the receiving layer increases accordingly. Therefore, by controlling the heating energy, it is possible to adjust the amount of fluid transfer of the molten material from the transfer layer to the receiving layer and the amount of color development. A colored image with a certain tonal density is formed. In addition, in the case of the present invention, the leuco dye is
Since it is located below the layer of thermofusible material that melts at a high temperature and melts at a low temperature, it does not transfer to the receptor layer all at once.

The heat-fusible substance used in the heat-sensitive transfer sheet of the present invention usually has a melt viscosity of 200 cp or more (at a temperature of 90°C), and it is preferable to use a substance whose melt viscosity has a large rate of change with respect to temperature. Note that the melt viscosity as used herein means the viscosity at or near the melting point of a thermofusible substance, and the rate of change in melt viscosity with respect to temperature is ΔV/ΔT (ΔV
: viscosity change, ΔT: temperature change), and the rate of change shows a negative value.

The melting point of the thermofusible substance used in the present invention is in the range of 200°C or lower, preferably 150°C or lower.

In the case of the present invention, the quantitative system of the melting point m4 of the leuco dye and the melting point m2 of the thermofusible substance is m1) mz (m1: melting point of the leuco dye, m1: melting point of the thermofusible substance).

Specific examples of the thermofusible substance used in the present invention are as follows:
For example, the following can be mentioned.

(1) Aliphatic amide compound R"NHCOR" represented by the following general formula (1) or (II) (1) (wherein, R2 is an alkyl group having 1 to 30 carbon atoms, R1゜R3 is a carbon number 10
-30 alkyl groups, R' and Rs are hydrogen or lower alkyl groups) 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, balmityl Acetamide, palmitylpropionamide, palmitylbutyramide, heptylacetamide,
heptylpropionamide, stearyl acetamide,
stearylpropionamide, stearylbutyramide,
stearyl valeramide, stearyl capronamide,
Stearyllaurinamide, stearyl palmitinamide, stearyl stearamide, nonadecylacetamide, nonadecylpropionamide, behenylacetamide, behenylpropionamide, behenylstearinamide, undecanoic acid methylamide, undecanoic acid ethylamide, lauric acid methylamide, lauric acid ethylamide, tridecanoic acid Methylamide, tridecanoic acid ethylamide, myristic acid methylamide, myristic acid ethylamide, pentadecanoic acid methylamide, pentadecanoic acid ethylamide, valmitic acid methylamide, valmitic acid dimethylamide, valmitic 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 amide compound represented by the following general formula (m) (wherein R'' is an alkyl group having 1 to 30 carbon atoms, R7,
(R8 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) Amide compounds 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, R10 is hydrogen, halogen or a lower alkyl group) (wherein Hll 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-2,4-dimethylbenzamide, N-cyclohexylpalmitic acid amide, N-(chlorohexyl)palmitic acid amide, N-(2-methyl cyclohexyl) stearic acid amide, N-stearylhexahydrobenzamide.

(4) A phenyl ester compound of hydroxybenzoic acid represented by the following general formula (IV).

(wherein, hydroxyl group, n is 0, 1.2 or 3, m is 1,2
or 3) Specific examples of such compounds include, for example.

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-dihydroxyphenyl) ester, 3-hydroxybenzoic acid (4-carboxyphenyl) ester, 4-hydroxybenzoic acid (4 -butoxyphenyl) ester, 4-hydroxybenzoic acid (・1-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-dichlorophenyl) ester, salicylic acid (2-
bromophenyl) ester, salicylic acid (4-bromophenyl) ester, salicylic acid (2,4-dibromophenyl) ester, salicylic acid (2,6-dibromophenyl) ester, salicylic acid (2,4,6-tribromophenyl) ester , salicylic acid (3-methylphenyl)
ester, salicylic rs1 (2,4-dimethylphenyl) ester, salicylic acid (4-tert, -butylphenyl) ester, salicylic acid (4-t, ert, -amylphenyl) 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!
ff (2-methoxy-4-allylphenyl) ester,
Salicylic acid (α-naphthyl) ester, salicylic acid (β
-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-diglorosalicylic acid (
2-methoxyphenyl) ester.

(5) Convex benzoic acid phenyl ester compound represented by the following general formula (■) (wherein R13 is hydrogen, an alkyl group having 1 to 30 carbon atoms or an alkoxy group, 2 halogens, a nitro group, a nitrile group,
Acyloxy group, substituted or unsubstituted aryl or aralkyl group, substituted or unsubstituted aryloxy or aralkyloxy group, R1'' is hydrogen, alkyl group or alkoxy group having 1 to 30 carbon atoms, 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 such compounds include, for example.

Examples 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-chlorphenyl ester Phenyl ester, benzoic acid-3-bromphenyl ester, benzoic acid-2,4-dibromphenyl ester, benzoic acid-
3-code phenyl ester, 3-nitrophenyl stethyl benzoate, 4-methyl-2,6-dichlorophenyl benzoate, 4-isopropylphenyl benzoate, 4-j-butyl benzoate Phenyl ester, benzoic acid-4-benzyl phenyl ester, benzoic acid Iv-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
-Me-1-xyphenyl ester, benzoic acid-4-(4-
methyl) phenoxyphenyl ester, 4-methylbenzoic acid phenyl ester, 4-methoxybenzoic acid phenyl ester, 4-phenoxybenzoic acid phenyl ester,
4-ace1-xybenzoic acid phenyl ester, 4-methoxybenzoic acid, 'J, aroma M-4-methoxyphenyl ester.

2-ace1-xybenzoic acid phenyl ester, 2-benzoyloxybenzoic acid phenyl ester, 2-21-lobenzoic acid-4-methylphenyl ester, 4-21-lobenzoic acid-4-methylphenyl ester .

4-benzoyloxybenzophenone, 2-benzoyloxy-4-methylbenzophenone.

(6) A benzoyloxybenzoic acid ester compound represented by the following general formula (■) (wherein R15 is hydrogen, an alkyl group or alkoxy group having 1 to 30 carbon atoms, or a halogen, and R'1' is a carbon number of 1 to 30).
30 alkyl groups, substituted or unsubstituted aryl or aralkyl groups) Specific examples of such compounds include, for example.

Examples include those shown below.

4-Benzoyloxybenzoic acid methyl ester.

4-benzoyloxybenzoic acid ethyl ester, 4-benzoyloxybenzoic acid-lowpropyl ester, 4-
Benzoyloxybenzoic acid benzyl ester, 4-benzoyloxybenzoic acid phenyl ester, 2-benzoyloxybenzoic acid phenyl ester, 4-(4'-methylbenzoic acid ethyl ester), 4
-(/I'-Me1-xybenzoyloxy)benzoic acid ethyl ester, 4-(4'-chloropenzoyloxy)benzoic acid ethyl ester.

(7) Ester compound represented by the following general formula (IX) (X) In the above formula, R,, R2, R3 and R4 all represent a higher alkyl group, and the number of carbon atoms thereof is usually 10 to 30°, preferably 16-22. Examples of this alkyl group include decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, hexadecyl, octadecyl, nonadecyl, eicosyl, and the like.

The leuco dye used in the thermal transfer sheet of the present invention includes:
Those applied to this type of heat-sensitive material can be arbitrarily applied. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferably used. . Specific examples of such leuco dyes include those shown below.

3.3-bis(P-dimethylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3.3-bis(P- dimethylaminophenyl)-6-dibutylaminophenyl, 3.3-bis(P-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6- Chlorfluorane, 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'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3
, 6-bis(diethylamino)-0-(o-chloroanilino)xantylbenzoic acid lactam).

3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7-(O-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-benzointrinopyrylospirane.

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)phthalide.

3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-(N-benzyl-trifluoro methylanilino)fluoran, 3-pyrrolidino-7-(di-P-chlorphenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl- ρ-Toluidino)-7-(α-phenylethylamino)fluoran.

3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(ρ-n
-butylanilino)fluorane, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
', 5'-benzofluorane, 3,6-simethoxyfluorane.

3-(p-dimethylaminophenyl)-3-phenyl phthalide, 3-di(1-ethyl-2-methylyldol)-3-yl-phthalide, 3-diethylamino-6-phenyl-7-azafluorane, 3 .3-bis(p-diethylaminophenyl)-6-dimethylaminophthalide, 2-bis(p-dimethylaminophenyl)methyl-5-
Dimethylamino-benzoic acid, 3-(p-dimethylaminophenyl)-3-(p-dibenzylaminophenyl)phthalide, :3-(N-ethyl-N-n-amyl)amino-6-methyl-7 - Aniritsu fluoran etc.

To produce the thermal transfer sheet of the present invention, paper, synthetic paper,
A transfer layer is provided by applying a coating solution containing a leuco dye onto a support sheet such as a plastic film, and a thermofusible substance is applied onto the transfer layer. A conventional binder can be added to the coating solution for forming the transfer layer in order to firmly bind the leuco dye to the porous sheet, but in this case, it is preferable that the softening point or melting point is 5
A thermoplastic or thermosetting resin having a temperature of 0 to 130°C is used.

Examples of such resins include polyethylene, polypropylene, polystyrene, petroleum resin, acrylic resin,
Vinyl chloride resin, vinyl acetate resin, vinylidene chloride resin, polyvinyl alcohol, cellulose resin, polyamide, polyacetal, polycarbonate, polyester,
Examples include fluororesin, silicone resin, natural rubber, chlorinated rubber, butadiene rubber, olefin rubber, phenol resin, urea resin, melamine resin, epoxy resin, and polyimide. When a porous sheet is impregnated with a coating liquid using these resins, a solvent coating method, a hot melt coating method, an aqueous emulsion coating method, etc. are employed, and it is particularly preferable to employ a solvent coating method.

What is the amount of leuco dye applied to the support sheet?

Usually 0.1-20g/m, preferably 0.3-10g
/rrr (dry solids basis).

When forming a thermofusible material layer on the transfer layer, the formation of the thermofusible material layer is carried out by various hot melt coating methods, aqueous emulsion coating methods, etc. i'(1+) is usually
0.1~20g/rtl, preferably 0.3~10g/
It is 汀f.

The thermal transfer sheet 1- of the present invention is used in combination with a receptor sheet having a receptor layer containing a color developer.

That is, the thermal transfer sheet 1 of the present invention is stacked on the receiving sheet 1- so that the transfer layer consisting of the leuco dye-impregnated layer and the thermofusible material layer is in contact with the receiving layer, and the transfer sheet 1 is gently transferred to the receiving sheet 1-. By thermally printing from the back side of the sheet, it is possible to form a colored image on the receiving sheet with a density corresponding to the printing energy.

As the color developer used in the receiving layer of the receiving sheet, an electron-accepting substance 1 such as a phenolic substance, an organic acid or a salt or ester thereof is used, and from the viewpoint of practicality, one having a melting point of 200°C or less is preferably used. is applicable. Specific examples of color developers preferably applied in the present invention are shown below.

'I tart-butylphenol, 4-hydroxydiphenyl ether, [-naphthol, 2-naphthol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, 2,2'-dihydroxydiphenyl ether, 4-phenylphenol, 4-l; crj
-octylcatechol, 2,2'-dihydroxydiphenyl, 4,4'-methylenebisphenol, 2.
2'-methylenebis(4-chlorophenol), 2.
2'-methylenebis(4-methyl-6-terheeptylphenol), 4,4'-isopropylidenediphenol, 4,4'-isopropylidenebis(2-
chlorophenol), 4,4'-isopropylidene bis(2゜6-dibromophenol), 4,4'-isopropylidene bis(2-tert-butylphenol), 4,7+'-isopropylidene bis(2-methylphenol) ), 4°4'-isopropylidene bis(2,
6-dimethylphenol), 4,4'-5ec-butylidene diphenol.

4.4'-5ea-butylidene bis(2-methylphenol), 4.4'-cyclohexylidene diphenol.

4.4'-Cyclohexylidenebis(2-methylphenol), salicylic acid, salicylic acid methalyl ester, salicylic acid phenacyl ester, 4-hydroxybenzoic acid methyl ester, 4-hydroxybenzoic acid ethyl ester, 4-hydroxybenzoic acid isopropyl ester , 4-hydroxybenzoic acid butyl ester, 4-hydroxybenzoic acid isoamyl ester, 4-hydroxybenzoic acid phenyl ester, 4-hydroxybenzoic acid benzyl ester, 4-hydroxybenzoic acid cyclohexyl ester, 5-hydroxybenzoic acid, 5-chlor Salicylic acid, 3-chlorosalicylic acid, thiosalicylic acid, 2-chloro-5-nitrobenzoic acid, 4-me-1-xyphenol, 2-hydroxybenzyl alcohol, 2,5-dimethylphenol, benzoic acid.

Orthotoluic acid, metatoluic acid, paratoluic acid,
Orthochlorobenzoic acid, metaoxybenzoic acid, 2,4-
dihydroxyacetophenone), resorcinol monobenzoate, 4-hydroxybenzophenone, 2,4
-dihydroxybenzophenone, 2-nano 1-ic
Acid, 1-hydroxy-2-naphthoic acid, 3,4-dihydroxybenzoic acid ethyl ester, 3
, 4-dihydroxybenzoic acid phenyl ester, 4-hydroxypropiophenone, salicyl salicylate, phthalic acid monobenzyl ester.

1.1-bis(4'-hydroxyphenyl)methane,
1.1-bis(4'-hydroxyphenyl)ethane,
1.1-bis(4'-hydroxyphenyl)propane, 1.1-his(4'-hydroxyphenyl)hexane, 1.1-bis(4'-hydroxyphenyl)hebutane.

1.1-bis(4'-hydroxyphenyl)-2-propylpentane.

1.1-bis(4'-hydroxyphenyl)-2-ethylhexane.

2.2-bis(4'-hydroxyphenyl)propane.

2.2-bis(4'-hydroxyphenyl)hexane, 2.2-bis(4'-hydroxyphenyl)hebutane, 3.3-bis(4'-hydroxyphenyl)hexane.

■, 1-bis(3'-methyl-4'-hydroxyphenyl)ethane.

1.1-bis(3'-methyl-4'-hydroxyphenyl)propane.

1.1-bis(3'-methyl-4'-hydroxyphenyl)butane.

1.1-bis(3'-methyl-4'-hydroxyphenyl)pentane.

■, 1-bis(3'-methyl-4'-bitroxyphenyl)hexane, ■, 1-bis(3'-methyl-4'-hydroxyphenyl)hebutane, 2-(3'-methyl-41 -Hydroxyphenyl)-
2-(4'-hydroxyphenyl)propane, 2.2
-bis(3'-methyl-4'-hydroxyphenyl)
Pentane, 2.2-bis(5'-methyl-4'-hydroxyphenyl)hexane, 2.2-bis(3'-methyl-4'-hydroxyphenyl).1-methylpentane.

1.1-bis(3'-methyl-4'-hydroxyphenyl)4-methylbutane.

3.3-bis(3'-methyl-4'-hydroxyphenyl)pentane, 3.3-bis(3'-methyl-4'-hydroxyphenyl)hexane, 5.5-bis(3'-methyl-4 '-Hydroxyphenyl)nonane, 2-(4'-hydroxyphenyl)-2-(3'-
Chlor-4'-hydroxyphenyl)propane, 2.2
-bis(3'-isopropyl-4'-hydroxyphenyl)propane, 2.2-bis(3'-tert-butyl-4'-hydroxyphenyl)propane, 2.2-bis(3'-chloro-4') -hydroxyphenyl)propane, 2-(4'-hydroxy-3',5'-dimethylphenyl)-2-(4'-hydroxyphenyl)propane.

Bis(3'-methyl-5'-ethyl-4'-hydroxyphenyl)methane, 1.1-(3'-methyl-5'-butyl-4'-hydroxyphenyl)butane, 2.2-bis(4 -hydroxyphenyl)octane.

Bis(4-hydroxyphenylmercapto)methane, 1.2-bis(4-hydroxyphenylmercapto)ethane.

■, 3-bis(4-hydroxyphenylmercapto)propane.

1.4-bis(4-hydroxyphenylmercapbutane.

1,5-bis(4-hydroxyphenylmercapto)ben'tane.

1,6-bis(4-hydroxyphenylmercapto)・
\xane, 1,3-bis(4-hydroxyphenylmercapto)acetone, 1,5-bis(4-hydroxyphenylmercapto)3
-Oxapentane, 1,7-bis(4-hydroxyphenylmercapto)3
, 5-dioxahebutane, 1,8-bis(4-hydroxyphenylmercapto)3
, 5-dioxaoctane, 4-benzylmercaptophenol 4-p-florbenzylmercaptophenol, 4-
11-methylbenzylmercaptophenol, etc.

For the receiving layer of the receiving sheet, in addition to the above-mentioned color developer 1p1, porous IIT. A material may be included. This porous filler has at least an oil absorption capacity.
¥, 50…0. /100g (JIS K5101
method), preferably 1.50m Q. / 100
g or more is used.

The proportion of the porous filler contained in the receptor layer is 1:1 of the color developer.
0.01 to 1 part by weight, preferably 0,0 parts by weight
It is 3 to 0.5 parts by weight. Specific examples of such porous fillers include inorganic and organic fine powders such as silica, aluminum silicate, alumina, aluminum hydroxide, magnesium hydroxide, urea-formalin resin, and styrene resin6. Also, various conventional binders can be used to strongly bond the receiving layer to the support sheet.

〔effect〕

The present invention is a six-layer transfer sheet having the above-mentioned structure, and when thermal transfer is performed in combination with a receiving sheet, a recorded image with excellent contrast properties can be obtained on the receiving sheet depending on the heating energy. Furthermore, this recorded image has excellent storage stability. In the present invention, a plurality of heat-sensitive transfer layers that develop different colors are provided, and by sequentially overlapping these layers on a receiving sheet to develop the colors, a multicolor image can be created.
You can do it.

〔Example〕

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

Example 1 (1) Creation of transfer sheet h (A-1) 3- N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane (melting point 206°C) 10 parts polyester resin (softening point 100°C) 3 parts of the product X were dissolved in 100 parts of methyl ethyl ketone and applied to the surface of a 6 μm thick polyester film using a wire bar and dried to form a leuco dye-containing transfer layer with a coating weight of 1 g/rrr. Formed.

Next, on the transfer layer, apply 1 part of the following thermofusible substance.
When drying the skin using a wire bar, the adhesion wind is 1.01;
/rrr to prepare a heat-sensitive transfer sheet (^-1).

Benzoic acid phenyl ester (melting point 71°C) 10 parts 5% methylcellulose aqueous solution 5 parts water
3
5 parts The melt viscosity of the thermofusible material layer is approximately 250c.
p (00°C).

(2) Preparation of receptor sheet (B-1) 20 parts of 4-hydroxybenzoic acid n-butyl ester Silica fine particles (oil absorption 200 m 11./100 g
) 10 parts polyvinyl alcohol
3 parts water
After dispersing 100 parts of the composition using a ball mill for 10 hours, it was coated and dried using a wire bar on the surface of high-quality paper (basis weight 35 g/rn) to obtain a receiving sheet (with a dry coverage of 5 g/rn). B-1) was obtained.

Next, the transfer sheet (A-1) obtained as described above
The transfer layer of and the receiving layer of the receiving sheet (B-1) are superimposed,
When an image was recorded from the back side of the transfer sheet using a thermal head with varying heating energy, a gray to black image was recorded on the receiving sheet as shown in the following table.

Table 1 From Table 1, it can be seen that when the thermal transfer sheet of the present invention is used, the image density changes in accordance with the change in heating energy, and gradation recording is possible. Further, even after this recorded image was stored in a constant temperature bath at 60° C. for 50 hours, the density of the recorded image hardly changed.

Example 2 (1) Preparation of transfer sheet (A-2) 15 parts of 3-diethylamino-7,8-benzfluorane (melting point 222°C) 4 parts of styrene resin (softening point 95°C) was mixed with 100 parts of methyl ethyl ketone. 6 μm J'7 polyester film 1 using a wire bar.
1 was coated and dried to form a transfer layer with a dry adhesion amount of 1 g/n.Next, on top of this, the following thermofusible +'1 substance dispersion was dried using a wire bar; Amount 1, to #n
The coating was applied and dried to prepare a thermal transfer sheet 1-(A-2).

N-stearylbenzamide (melting point 85°C) 10 parts 5%
Methylcellulose aqueous solution 5 parts water
35
Note that the melt viscosity of the thermofusible material layer is approximately 300 cp.
(90°C).

(2) Preparation of receptor sheet (El-2) 2.2-bis (
4'-Hydroxyphenyl)heptane 20 parts Silica fine particles (200 m Q / 100 g per oil absorption 1)
) 10 parts polyvinyl alcohol
3 parts water
After dispersing 100 parts of the composition for 10 hours using a ball mill, it was coated and dried using a wire bar on the surface of high-quality paper (basis weight 35 g/proof) to obtain a receptor sheet (B) with a dry coverage of 5 g/I. -1) was obtained.

Next, the transfer sheet (8-2) obtained as described above
The transfer layer of and the receiving layer of receiving sheet 1-([3-2) were superimposed and image recording was performed in the same manner as in Example 1.

As shown in Table-2 below, the receiving sea 1- (11-2)
Images ranging from light pink to deep red were recorded on L, demonstrating that it was possible to record images with gradation.

Table-2

Claims (1)

[Claims] (1) Provide a transfer layer containing a leuco dye on a support,
1. A heat-sensitive transfer sheet used in combination with a receptor sheet having a color developer layer for the leuco dye, characterized in that a layer of a thermofusible material that melts at a lower temperature than the leuco dye is provided thereon.