JPS59192593A - Thermal transfer medium - Google Patents

Abstract

PURPOSE:To enable to produce a uniform image with high density, by a method wherein a heat-fusible substance is incorporated in an image-receiving layer, and average particle diameters of the heat-fusible substance and a color developer are set to be not layer than a specified value. CONSTITUTION:In an image-receiving sheet, the image-receiving layer comprising a color developer for a leuco dye and a heat-fusible substance in the form of minute particles having an average particle diameter of not larger than 1mum is provided on a base such as a paper, a synthetic paper or a plastic film. When producing the image-receiving sheet, layer-forming components such as the color developer and the heat-fusible substance are dispersed or dissolved in a medium such as water by a crushing and mixing means such as a ball mill, an attriter or a sand mill, and the resulant dispersion or solution is applied to the base. To provide a transfer layer comprising a leuco dye and a porous filler on a transfer sheet, a coating liquid in which the leuco dye is dissolved and the porous filler is dispersed is applied to a base such as a paper, and is dried. Accordingly, since the leuco dye and the color developer are provided separately on separate bases, the problem of color development of fogging during production or preservation is completely obviated. By the presence of the color developer and the heat-fusible substance in a minute form, an extremely clear image can be obtained with an enhanced image density.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a thermal transfer medium capable of obtaining a high-density image and a transfer image having a uniform image density even after multiple transfers. [Prior Art] Conventionally, thermal transfer media include those consisting of a transfer sheet with a heat-sublimable dye layer provided on a support and a receiving sheet that receives a sublimable dye image by thermal printing from the back side of this sheet, and A combination of a transfer sheet and a receiving sheet is known, in which a transfer layer of a fusible substance and a pigment or dye is provided on a support. The latter medium is a transfer layer with pigments or dyes dispersed in a thermofusible material, making it difficult to carry high-density images. If a large amount of pigment is included for the purpose of obtaining an image, the transfer efficiency will be lowered, making it difficult to obtain a high-density image. Since the fusible substance migrates to the receiving sheet side, when the transfer sheet and the receiving sheet are peeled off, the transfer sheet and the receiving sheet cannot be peeled off smoothly, resulting in problems such as the image area of fine lines 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 reactive, but when face-to-face contact occurs,
If the transfer layer simply transfers to the receiving layer, a sufficient coloring reaction will not occur, resulting in a low-density image.If the heating conditions are set to higher temperature and longer thermal printing to promote 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 present inventors first attempted to improve the above-mentioned drawbacks by
We have proposed a thermal transfer medium in which a thermofusible substance is blended into the receptor layer provided on the receptor sheet, or a thermal transfer medium in which a polymer resin with a minimum film formation temperature of 40°C or less is used as a binder. It is still not sufficient to overcome the drawbacks mentioned above.

〔the purpose〕

The present invention provides a thermal transfer medium which has higher sensitivity and can provide images with higher density than the various thermal transfer media described above, and also allows transfer of a small amount of leuco dye component from the transfer layer to the receiving layer. An object of the present invention is to provide a heat-sensitive transfer medium that can provide a uniform and high-density image even after multiple transfers.

〔composition〕

According to the present invention, the transfer notebook includes a transfer layer containing a leuco dye as a main component, and a receiving sheet having a receiving layer containing a color developer as a main component for the leuco dye, and the receiving layer includes a thermoplastic resin. There is provided a heat-sensitive transfer medium characterized in that it contains a fusible substance and the average particle size of the thermofusible substance and color developer is 1 μm or less.

A thermal transfer medium has a structure in which a receiving sheet is stacked on a transfer sheet so that its receiving layer is in contact with the transfer layer of the transfer sheet. A desired colored image is formed on the sheet surface. In the present invention, as described above, a thermofusible substance is blended in the receptor layer, and furthermore, the particle size of the color developer and the thermofusible substance in this layer is on average one size smaller than the other. Therefore, when the transfer layer and the receptor layer are brought into contact with each other and heated, the leuco dye transferred from the transfer layer to the receptor layer easily reacts with the color developer in the receptor layer, resulting in a clear, high-concentration color. An image is formed on the receiver sheet.

That is, in this receiving layer, the thermofusible substance acts as a good reaction medium for the leuco dye and the color developer when heated, promoting the color reaction of both components, and Since the particle size of the color substance and the color developer are fine particles with an average particle size of 1 μm or less, it is possible to form extremely clear images.

On the other hand, if a thermofusible substance is not incorporated into the receptor layer, or if the particle size of this substance and the color developer is larger than 1 μm, the density of the developed image will be low and the clarity of the image will be reduced. and give unfavorable results.

In the present invention, the thermofusible substance contained in the receptor layer is 2
It is an organic compound having a melting temperature of 00°C or lower, preferably 150°C or lower, and can be selected from a wide range of groups. Examples of thermofusible substances suitable for the present invention are as follows.

(1) Aliphatic amide compound represented by the following general formula (I) or (I[) 5-R'NHCOR2(I) (wherein, R2 is an alkyl group having 1 to 3 carbon atoms, R, l.

R3 is an alkyl group having 10 to 3 carbon atoms, R' I B5
is hydrogen or a lower alkyl group) Specific examples of such fatty acid amides include the following.

Decylacetamide, decylzolopionamide, undecyl acetamide, undecylpropionamide P1 lauryl acetamide P1 lauryl propionamide, tridecyl acetamide 1, tridecyl propionamide,
Myristylacetamide, myristylzolopionamide, pentadecyl acetamide, hentadecylpropionamide P1 palmitylacetamide, palmitylpropionamide, ξlumitylbutyrami P1 heptylacetamide P1 heptylpropionamide, stearyl acetamide, stearylpropionamide, stear 6-lylbutyramide, Stearyl valeramide 1, stearyl capronamide, stearyl lauramide, stearyl no ξ lumitin amide P1 stearyl stearamide, nonadecylacetamide, nonadecylpropionamide, behenylacetamide, behenylpropionamide, hehenylstearamide, undecanoic acid methylamide, undecanoic acid Ethylamide, methyl laurate, ethyl lauric acid, methyl amide tridecanoate P1 ethyl amide tridecanoate, methyl amide myristic acid, ethyl myristic acid, methyl amide pentadecanoate P, ethyl amide pentadecanoate, methyl amide nomylmitic acid P1 dimethyl amide palmitate, butyramide tsucurmitate, stearic acid methylamide,
Stearic acid ethylamide, stearic acid propylamide, stearic acid butyv-ysV, -7-9
7') y@,) fyIy7 S I', 7 Careic acid noethylamide, stearic acid dibutylamide, nonadecanoic acid methylamide P1 Nonadecanoic acid ethylamide, behenic acid methylamide, oleic acid methylamide, oleic acid ethylamide.

(2) An aromatic carboxylic acid amide compound represented by the following general formula (g) (wherein R6 is an alkyl group having 1 to 3 carbon atoms,
(8 is hydrogen, halogen, lower alkyl group or lower alkoxy group, and n is 0 or 1) Specific examples of such compounds include those shown below.

N-stearylbenzamide, N-noglumityl-2-
Chlorobenzamide, N-stear IJ Roux 2-methoxybenzamide Y, N-stearyl-4-methylbenzamyl r1N-7ξlumityl-2,4-y methylbenzamide, N-behenylbenzamide, N-behenyl-2 −
methylbenzami) l', N-stearylphenylacetylamide, N-behenylphenylacetylamide.

(3) An amide compound having a cyclohexyl ring represented by the following general formulas (1) and (V) (wherein R9 is an alkyl group having 1 to 30 carbon atoms or a substituted or unsubstituted aryl group, RIO is hydrogen,... or a lower alkyl group) (in the formula, R11 has 1 carbon number)
-30 alkyl group, RI2 is hydrogen, halogen or lower alkyl group) Specific examples of such compounds include those shown below.

N-cyclohexyl acetamide, N-cyclohexylluprobionamide, N-cyclohexylstearamide, N-cyclohexylpenzamide, N-cyclohexyl-2-methylbenzamide P1 N-cyclohexyl-2-chlorobenzamide , N-cyclohexyl-2
, 4-J methylpenzamide, N-cyclohexylpalmitic acid amide)', N-(chlorohexyl)nomylmitic acid amide 9-1', N-(2-methylcyclohexyl) stearic acid amide, N-stearylhexahydro Penzami do.

(4) A phenyl ester compound of hydroxybenzoic acid represented by the following general formula (b) (wherein, group, substituted or unsubstituted aryloxy, aralkyloxy group, carzene acid group or hydroxyl group, n is 0, 1.2 or 3, m is 1.2
or 3) Specific examples of such compounds include those shown below.

4-hydroxybenzoic acid phenyl ester, 4-hydroxybenzoic acid (2-methoxyphenyl)-10~ ester, 4-hydroxybenzoic acid (2-methoxy-4
-methylphenyl) ester, 4-hydroxybenzoic acid (3,5-)hydroxyphenyl) ester, 3-hydroxybenzoic acid (4-carboxyphenyl) ester,
4-hydroxybenzoic acid (4-butoxyphenyl) ester, 4-hydrobenzoic 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-) dichlorophenyl) ester, salicylic acid (2-bromophenyl) ester, salicylic acid (4-bromophenyl) ester, salicylic acid (2,4,6-) dichlorophenyl) ester, 4
-dibromophenyl) ester, salicylic acid (2,6-
dibromophenyl) ester, 'ゝ salicylic acid (
2,4,6-)dibromophenyl) ester, salicylic acid (3-methylphenyl) ester, salicylic acid (2,
4-, ) methylphenyl) ester, salicylic acid (4-
tcrt-butylphenyl) ester, salicylic acid (4
-1erl-amylphenyl) ester, salicylic acid (
2-methoxyphenyl) ester, salicylic acid (2-ethoxyphenyl) ester, salicylic acid (3-7toxyphenyl) ester, salicylic acid (4-hydroxyphenyl) ester, salicylic acid (4-benzylphenyl) ester
Esters, salicylic acid (4-benzoylphenyl) ester, salicylic acid (2-methoxy-4-allylphenyl) ester, salicylic acid (α-naphthyl) ester, salicylic acid (β-naphthyl) ester, salicylic acid (4-
10 rho 3-methylphenyl) ester, salicylic acid (
3-hip C1-IF diphenyl) ester, salicylic acid (4-f lobenylphenyl) ester, 5-chlorosalicylic acid (3-methylphenyl) ester, 3,5-dichlorosalicylic acid (2-methoxyphenyl) ester.

(5) Benzoic acid phenyl ester compound BI3 R+4 represented by the following general formula (VIT) (wherein B+3 is hydrogen, an alkyl group or alkoxy group having 1 to 30 carbon atoms,... rogene, nitro group, nitrile group, acyloxy group, substituted or unsubstituted aryl, aralkyl group, substituted or unsubstituted aryloxy or aralkyloxy group, R14 is hydrogen, carbon number 1-30
Alkyl group 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 Specific examples of such compounds (which are groups) include those shown below.

Benzoic acid phenyl ester, benzoic acid-4-methylphenyl ester, benzoic acid-2,4-dichlorophenyl ester, benzoic acid-2,4,6-tric-13-lorphenyl ester, benzoic acid-2-methyl-4 -Chlorphenyl ester, benzoic acid-3-bromphenyl ester, benzoic acid e2+4) fromphenyl ester, benzoic acid-3-iodophenyl ester, benzoic acid-3-ditrophenyl ester, benzoic acid-
4-Methyl-2,6-dichlorophenyl ester, benzoic acid-4-isopropylphenyl ester, benzoic acid ~
4-t-7'tylphenyl ester, benzoic acid-4-pennorphenyl ester, benzoic acid 4 (1-naphthyl) phenyl ester, benzoic acid e-2-benzoyloxyphenyl ester, benzoic acid-4-(2-methyl) ) diphenyl ester, benzoic e-2-phenylethyloxyphenyl ester, benzoic acid-2-acetoxyphenyl ester, benzoic acid-4-methoxyphenyl ester, benzoic acid e-4-C4-methyl)phenoxyphenyl ester, 4-methylbenzoic acid acid phenyl ester, 4-methoxybenzoic acid phenyl ester, 4-phenoxybenzoic acid phenyl ester, 4-acetoxybenzoic acid phenyl ester 1
4-enyl ester, 4-methoxybenzoic acid-4-methoxyphenyl ester, 2-acetoxybenzoic 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) A benzoyloxybenzoic acid ester compound represented by the following general formula (■) (wherein R, +5 is hydrogen, an alkyl group or alkoxy group having 1 to 30 carbon atoms, or a halogen, R16 is 3 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 - Bensoyl, t
-xybenzoic acid phenyl ester, 4-(4'-methylbenzoyloxy)benzoic acid ethyl ester, 4-(4
'-Methoxybenzyloxy)benzoic acid ethyl ester, 4-(4'-chlorobenzoyloxy)benzoic acid ethyl ester.

The above thermofusible substance is used in an amount of 0.1 per part by weight of leuco dye.
~50 parts by weight. Note that, if necessary, an appropriate amount of the above-mentioned thermofusible substance can be added to the transfer layer.

In the present invention, the color developer blended into the receptor layer is an electron-accepting substance, such as a phenolic substance, an organic acid, or its salt or ester, and from the viewpoint of practicality, preferably has a melting point of 200°C or less. are used. Specific examples of color developers preferably used in the present invention are shown below. In addition,
Numbers in parentheses indicate melting points in degrees Celsius.

4-1erl-butylphenol (98), 4-hydroxydiphenyl ether (84), 1-naphthol (9
8), 2-naphthol (121), methyl-4-hydroxybenzoate (131), 4-hydroxyacetophenone (109), 2,21-dihydroxydiphenyl ether (79), 4-phenylphenol (166)
,4. -terj-octylcatechol (109), 2
．． 2I-dihydroxydiphenyl (103), 4,4'
-Methylenebisphenol (160), 2.2'-methylenebis(4-chlorophenol) (164), 2.2
'-methylenebis(4-methyl~6-jert-7
'Tylphenol) (125), 4,4'-isopropylidene diphenol (156), 4,41-impropylidene bis(2-chlorophenol) (90), 4,4
1-inpropylidene bis(2,6-dibromophenol) (172), 4,4′-isopropylidene bis(2
-tert-butylphenol) (110), 4.4'
-isopropylidene bis(2-methylphenol) (1
36), 4,41-y17-impropylidene bis(2,6-dimethylphenol) (
168), 4+4'-5ee-butylidene diphenol (119), 4+4'-5ec-butylidene bis(
2-methylphenol) (142), 4,4'-cyclohexylidene diphenol (18o), 4,4'-cyclohexylitine bis(2-methylphenol) (184
), salicylic acid (163:), salicylic acid m −)!
J ester (74), salicylic acid phenacyl ester (110), 4-hydroxybenzoic acid butyl ester (
131), t-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 phenyl ester (S
O), 4-hydroxybenzoic acid phenyl ester (17
8), 4-hydroxybenzoic acid benzyl ester (11
1), 4-Yo-IF Cybenzoic e cyclohexyl ester (119), 5-Hydroxysalicylic acid (
200), 5-chlorsalicylic acid (172), 3-chlorsalicylic acid (178), thiosalicylic acid (164),
2-chloro-518- -nitrobenzoic acid (165), 4-methoxyphenol (53), 2-hydroxybenzyl alcohol (87)
, 2,5-dimethylphenol (75), benzoic acid (1
22), 0-toluic acid (107), m-toluic acid (
111), p-toluic acid (181), 0-chlorobenzoic acid (142), m-hydroxybenzoic acid (200),
2.4-,) hydroxyacetophenone (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--p-hydroxybenzoic acid phenyl ester (1
89), 4-hydroxypropio7xnon (tso),
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. A phenolic substance can be easily synthesized in high yield, with high purity, and at a relatively low cost by reacting monothiohydroquinone with a corresponding dihalogenoalkyl ether under tra-alkaline conditions.

In the phenolic substance represented by the above general formula, R
The ether group therein may be in the main chain of the alkylene group or in a 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 those containing 1 to 3 ether bonds and having 2 to 7 carbon atoms.

Specific examples of the phenolic substance represented by the above general formula include those shown below.

Compound No. Structural Formula % Formula % The compound represented by the general formula (IX) described above has excellent heat sensitivity, and is particularly excellent in high-speed recording properties.

Furthermore, zinc chloride can be used as the color developer. This color developer containing zinc chloride provides a transferred colored image with excellent plasticizer resistance and solvent resistance.

The transfer sheet used in the present invention is sheet paper, synthetic paper,
A transfer layer containing a leuco dye as a main component and a porous filler as an auxiliary component is provided on a support such as a plastic film. As the leuco dye in this case, any of those conventionally used for pressure-sensitive paper and thermal paper can be used, and triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based ones are preferably used. be done. Specific examples of these leuco dyes are shown below.

3+3-His(p-dimethylaminophenyl)-phthalide 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as Crystal 22-noζioletlactone) 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide -dimethylaminophenyl)-6-diethylaminophthariP 313- His(p-dimethylaminophenyl)-6-
Chlorphtally P 3.3-bis(p-dibutylaminophenyl)phthalate S 3-cyclohexylamino-6-chlorofluoran 3-(N・N-diethylamino)-5-methyl-7(N
IN y hensylamino)fluoran 3-dimethylamine-5,7-dimethylfluoran 3-diethylamino-7-methylfluoran 3-)ethylamino-7,8--3: fluoran 3-diethylamine-6-methyl-7 -Chlor\ Fluorane 3-pyrrolidino-6-methyl-7-anilinofluorane 2-(N-(3'-)'J chlorylmethylphenyl)amine)-6-dinithylaminofluorane 2- (3, 6
-bis(diethylamino) -9-(0-chloroanilino)xantylbenzoic acid lactam) 3-diethylamino-'r-(o-chloroanilino)fluoran 3-dibutylamino-7-(0-chloroanilino)fluoran 3-N-methyl- N-amylamino-6-methyl-7-
Anilinofluoran 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran 3-(2-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5' -chlorophenyl)phthalide 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxyl 5-m; trophenyl)
Phthalide 3-(2'-hydroxy-4'-diethylaminophenyl) -3-(2'-methoxy-5'-methylphenyl)phthalide 3-(2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-41-chloro-5'-
methylphenyl) phtari F″′.

The amount of the leuco dye mentioned above is usually 0.3 to 30 g based on the support.
/m2, preferably about 0.5 to 20 g/I'r+2.

In the present invention, the porous filler that can be incorporated into the transfer layer provides a high-density image even after multiple transfers. This porous filler has an oil absorption of at least 50mA! /1
00g (according to JISK5101 method), preferably 15
0m17100g or more is used. If the oil absorption amount is less than 50 ml/100 g, the object of the present invention cannot be fully achieved. The proportion of porous filler contained in the transfer layer is 0.0 per weight of leuco dye.
The amount is 1 to 1 part by weight, preferably 0.03 to 0.5 part by weight. Specific examples of porous fillers used in the present invention include inorganic and organic microorganisms such as silica, aluminum silicate, alumina, aluminum hydroxide, magne/lamb hydroxide, urea-formalin resin, and styrene resin. It is a powder.

In the present invention, the oil absorption amount is 50 d for the receptor layer as well.
It is preferable to include porous filler in an amount of /100 g or more, but it can be omitted depending on the case. The porous filler contained in the receptor layer is 0.01 parts by weight or more, usually 0.805 to 10 parts by weight, per 1 part by weight of the color developer.
Preferably it is in the range of 0.81 to 3 parts by weight.

The receptor sheet used in the present invention has a receptor layer containing a color developer for leuco dye and a thermofusible substance in the form of fine particles with an average particle size of 1 μm or less on a support such as paper, synthetic paper, or plastic film. It is something. In order to manufacture this receptor sheet, layer forming components such as a color developer and a thermofusible substance are dispersed or dissolved together with a medium such as water using a pulverizing and mixing means such as a ball mill, attritor, or Sun 13 mill. is applied onto the above-mentioned support. When drying the receptor layer, it is preferable that the color developer and heat-fusible substance are once thermally melted at a temperature higher than their melting point, or alternatively, the color developer and heat-fusible substance are mixed with an organic compound. It is also preferable to apply a solution dissolved in a solvent to the support as a coating solution. In any case, it is necessary to form the color developer and the thermofusible substance into fine particles having an average particle size of 1 μm or less by the above-mentioned pulverizing and mixing means.

In order to form a transfer layer containing a leuco dye and a porous filler on a transfer sheet, a coating solution in which the leuco dye is dissolved and a porous filler is dispersed is applied to the support such as the paper mentioned above, and then dried. It is convenient to let

Furthermore, the surface smoothness (Beckman smoothness, JIS-P811
It is also effective to adjust 9) to 200 to 1000 seconds.

In addition, when a transfer layer or a receiving layer is provided on each support, a conventional binder is used as the binder.
such as polyvinyl alcohol, methoxy), cellulose, hydroxyethylcellulose, carboquine methylcellulose, polyvinylpyrroli, polyacrylamide, polyacrylic acid, starch, gelatin, polystyrene, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, etc. Water-soluble, organic solvent-soluble or aqueous emulsion-forming resins can be used.

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. It may be provided in

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 with an image-like transfer layer have a
It can be obtained by applying the transfer layer forming liquid in the form of a desired image (including letters) by letterpress printing or gravure printing, or by applying the transfer layer forming liquid to the surface of the image-free transfer layer of the above-mentioned transfer sheet. , overlap the surfaces of appropriate supports such as paper, synthetic paper, plastic film, etc., and apply an image from the support side or the transfer sheet side using a suppressing means such as a typewriter or iron pen, or a heating suppressing means such as a thermal head or heat wave. The image-free transfer layer of the transfer sheet can be imagewise adhered to the surface of another suitable support by pressing the transfer sheet in a manner similar to that shown in FIG.

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 the receiving sheet is placed on the surface of the transfer layer of the transfer sheet, and the thermal This can be done by direct heating printing using a printer, or by overlaying the receiving layer of a receiving sheet on the transfer layer of the transfer sheet, and then writing an original image written in black ink on the back of the transfer sheet. This can be done by placing them in close contact with each other, irradiating infrared rays from the side of the receiving sheet surface, and selectively heating only the black image area in the original image to a high temperature (in this case, the transfer sheet and the receiving sheet are (Both materials must be transparent to infrared rays.)

291 In thermal transfer as in the present invention, by repeating the above operations 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. By forming a transfer and reverse transfer image on the receiving sort, blue and red colored images can be formed on the same sheet.

〔effect〕

In the present invention, the leuco dye and its color developer are separated and contained on separate supports, which eliminates color fog during manufacture and storage, which is seen with conventional thermal paper. No problems arise. Furthermore, the obtained copy contains only a color developer and no leuco dye in the non-image area, so no color development occurs even if it is heated (in other words, it is not fully fixable). be). Also, a small amount of heating energy such as a thermal head can generate high
- It is economical because a high density image can be obtained 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 layer of the receiving sheet is uniform, and the dye transfer occurs little by little during transfer, so the image density of the resulting copies is is equalized. Furthermore, when heated, the thermofusible substance provides a good reaction medium for the reaction of the leuco dye and color developer, so the color reaction is accelerated.
By the presence of finely divided color developers and thermofusible materials, images can be obtained with great sharpness and increased image density.

〔Example〕

Next, the present invention will be further explained in detail with reference to Examples and Comparative Examples.

Example 1 ``CA) Creation of transfer sheet Carnauba wax 1
0g crystal violet lactone
20g Norica fine particles (oil absorption 300ml 1100g)
1 g ethyl cellulose
5g water
After dispersing 100 g of the composition for 24 hours using a ball mill, it was applied onto the surface of a 12 μm thick roughened polyester film using a wire S- and dried to prepare a transfer sheet with a coating weight of 10 g/m 2 .

(B) Creation of acceptance sort 4 ~ Hydroxybenzoic acid n-butyl ester
20g silica particles (oil absorption 200m7!//100g
) 10 g methyl 4-benzoyloxybenzoate 20 g ethyl cellulose
A composition consisting of 2 g of 100 g of methyl ethyl ketone was dispersed and mixed for 24 hours using an i-lumil to prepare a dispersion liquid in which the average particle size of solid particles was 0.1 μm (as measured by Nanosizer, a fine particle size measuring device manufactured by Coulter Co.), It was coated on the surface of high-quality paper (35 g/m2) using a wire parser and dried to prepare a receiving sheet with a coverage of 5 g/m2.

The receiving layer of the receiving sheet is stacked so as to be in contact with the transfer layer surface of the transfer sheet obtained in this way, and then 1 millijoule of heating energy is applied from the back side of the transfer sheet using a thermal head to develop color. The density and sharpness of the images were evaluated. The results are shown in Table 1.

Example 2 Example I except that bisphenol A and salicylic acid (2-methoxyphenyl) ester were used in place of 4-hydroxybenzoic acid n-butyl ester and methyl 4-benzoyloxybenzoate described in Example 1, respectively. A receiving sheet was prepared in the same manner as above.

The receptor sheet thus obtained was placed on the transfer sheet obtained in Example 1, heated and colored in the same manner as in Example 1, and the density and sharpness of the obtained image were evaluated. The results are also shown in Table 1.

Comparative example 1 4-hydroxybenzoic acid n-butyl ester 2
0g Nrika fine particles (oil absorption 200m7!//100g)
10 g Methyl 4-benzoyloxybenzoate 20 g Hydroxyethyl cellulose (10% aqueous solution) 20 g 33- Water
A composition consisting of 82g was milled using a ball mill for 24 hours.
A dispersion liquid having an average particle size of solid particles of 5 μm (measured in the same manner as in Example 1) was prepared by time-dispersed mixing, and it was applied to the surface of high-quality paper (35 g/m2) using a wire spar. Then, it was dried to prepare a receiving sheet with a coverage of 5 g and 7 m2.

The receiving sheet thus obtained was tested in the same manner as described in Example 1 to evaluate the density and sharpness of the image obtained. The results are shown in Table 1.

Comparative Example 2 Example 1 except that bisphenol A and salicylic acid (2-methoxyphenyl) ester were used instead of 4-hydroxybenzoic acid n-butyl ester and methyl 4-benzoyloxybenzoate described in Comparative Example 1. A receiving sheet for comparison was prepared in the same manner as above.

The receiving sheet thus obtained was tested in the same manner as described in Example 1 to evaluate the density and sharpness of the resulting image. This result is also shown in Table 1.
Shown below.

Table 1 As is clear from this comparison, the images obtained in Examples 1 and 2 had higher density and better clarity than those obtained in Comparative Examples 1 and 2. Therefore, it was found that the media obtained in Examples 1 and 2 were fixed thermal transfer media that could be put to practical use.

Patent applicant Ricoh Co., Ltd. Agent Patent Attorney Ikeura Distributed 35-

Claims (1)

[Claims] (1) Consisting of a transfer sheet having a transfer layer containing a leuco dye as a main component, and a receiving sheet having a receiving layer containing a color developer as a main component for the leuco dye, a thermofusible substance is contained in the receiving layer. A heat-sensitive transfer medium, characterized in that the heat-fusible substance and the color developer have an average particle size of 1 μm or less.