JPS61192596A - Receiving sheet for thermal transfer - Google Patents

Abstract

PURPOSE:To enhance heat sensitivity and storage stability and to improve the gradation expression of image density, by forming a receiving layer containing a coupler, which is used in combination with a transfer sheet having a leuco dye layer, from two layers different in a melting property. CONSTITUTION:A receiving layer containing a coupler to a leuco dye, which is used in combination with a transfer sheet having a transfer layer containing a leuco dye, is formed of a lower layer A and an upper layer B. The upper layer B has a low temp. melting property as compared with the lower layer A. That is, the m.p. of the coupler of the upper layer B is pref. so as to be lower than that of the lower layer A by about 90-20 deg.C. Thus constituted receiving sheet imparts density having gradation corresponding to heating energy by a method wherein the transfer sheet having the transfer layer containing the leuco dye is superposed so as to contact the receiving layer thereof with the transfer layer and heated while heating energy is changed from the back surface of the transfer sheet. That is, because a color forming amount can be changed by controlling heating energy, an image excellent in gradation can be obtained.

Description

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

[Prior art]

Conventionally, thermal transfer methods use 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 receiving 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 image density, it has the disadvantages of low heat sensitivity and poor storage stability. A heat-sensitive transfer sheet in which a heat-fusible substance and a pigment are provided on a support has excellent heat sensitivity and storage stability, but has the disadvantage that it cannot express gradation at a single image level.

〔the purpose〕

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

〔composition〕

According to the present invention, the receiving layer is used in combination with a transfer sheet having a transfer layer containing a leuco dye, and includes a lower layer (A) and an upper layer (B) containing a color developer for the leuco dye. , and the upper layer (B) has a lower melting temperature than the lower layer (A).

The receptor sheet of the present invention is one in which a receptor layer consisting of a lower layer (A) and an upper layer (B) containing a color developer is provided on a support such as one sheet of synthetic paper or a plastic film. , the color developer in the upper layer (B) has a lower melting point than the color developer in the lower layer (A).
) The melting point of the color developer is 90-20% higher than that of the lower layer (A).
℃, preferably about 70 to 30 degrees Celsius. If this melting point difference becomes too large, the melting point of the lower layer (A) will become too high and it will be difficult to obtain a one-tone image. On the other hand, if this melting point difference becomes too small, it will not be possible to obtain a satisfactory final gradation. I can't get a sexual image.

The receptor sheet of the present invention is produced by stacking a transfer sheet having a transfer layer containing a leuco dye thereon so that the receptor layer and the transfer layer are in contact with each other, and heating the transfer sheet from the back side while changing heating energy. It provides an image with gradation density depending on the heating energy. That is, when low heating energy is applied, the color developer in the upper layer (B) reacts with the transfer layer to form an image, and when higher heating energy is applied, both the lower layer (A) and the upper layer (B) react with the transfer layer. An image is formed by the reaction, and when intermediate heating energy is further applied, parts of the upper layer (B) and the lower layer (A) react with the transfer layer to form an image. In this way, in the present invention,
By controlling the heating energy, the amount of color development can be changed, so an image with excellent gradation can be obtained.

As the color developer used in the lower layer (A) and the upper layer (B) forming the receptor layer of the present invention, electron-accepting substances 1 such as phenolic substances, organic acids, salts or esters thereof, etc. are 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-
Hydroxylcidiphenyl Ayo 4) Ki,■-naphthol (98)
.

2-naphthol (121), methyl-4-hydroxybenzoate (131), 4-hydroxyacetophenone (109), 2,2'-dihydroxydiphenyl ether (79), 4-phenylphenol (166),
4-tart-octylcatechol (109),
2.2'-dihydroxydiphenyl (103), 4.
4'-methylenebisphenol (160), 2.2
'-methylenebis(4-chlorophenol) (164
), 2,2'-methylenebis(4-methyl-6-7e
rt-Butylphenol propylidene diphenol (156), 4,4'-isopropylidene bis(2-chlorophenol) (90)
, 4.4'-isopropylidene bis(2,6-dibromophenol) (172), 4.4'-isopropylidene bis(2-tart-butylphenol) (
110), 4.4'-isopropylidene bis(2-methylphenol) (136), 4.4'-isopropylidene bis(2,6-dimethylphenol) (168)
, /1.4'-see-butylidene diphenol (
119), 4.4'-see-butylidene bis(2-
methylphenol) (142), 4,c-cyclohexylidene diphenol (180), 4,4'-cyclohexylidene bis(2-methylphenol) (18
4), salicylic acid (163), salicylic acid methalyl ester (74), salicylic acid phenacyl ester (11)
0), 4-hydroxybenzoic acid methyl ester (13
1), 4-hydroxybenzoic acid ethyl ester (11
6), 4-hydroxybenzoic acid propyl ester (9
8), 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 (17g), thiosalicylic acid (164), 2-
Chloro-5-nitrobenzoic acid (165'), 4-methyhexyphenol (53), 2-hydroxybenzyl alcohol (87), 2,5-dimethylphenol (75
), benzoic acid (122), orthotoluic acid (107
), meta-1-luic acid (111), para-toluic acid (1
81), 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 (14g), phthalic acid monobenzyl ester (107)
), 1.1-bis(4'-hydroxyphenyl)ethane (126), ■, 1-bis(4'-hydroxyphenyl)propane (130), 1.1-bis(4'-hydroxyphenyl)hexane (111).

1.1-bis(4'-hydroxyphenyl)hebutane (120), 1. L-bis(4'-hydroxyphenyl)-2-propylpentane (128), 1.1-
Bis(4'-hydroxyphenyl)-2-ethylhexane (87), 2.2-bis(4'-hydroxyphenyl)propane (101).

3.3-bis(4'-hydroxyphenyl)hexane (155), 1.1-bis(3'-methyl-41-
hydroxyphenyl)ethane (101), 1,1-bis(3'-methyl-4'-hydroxyphenyl)propane (94).

1.1-bis(3'-methyl-4'-hydroxyphenyl)butane (135), 1.1-bis(3'-methyl-4'-hydroxyphenyl)pentane (97),
1.1-bis(3'-methyl-4'-bitroxyphenyl)hexane (7B), 1.1-bis(3'-methyl-4'-hydroxyphenyl)hebutane (8s),
2-(3'-methyl-4'-hydroxyphenyl)-
2-(4'-hydroxyphenyl)-2-(4'-
hydroxyphenyl)propane (1,20), 2.2
-bis(3-methyl-4'-hydroxyphenyl)pentane (128), 2,2-bis(5-methyl-4'
-hydroxyphenyl)hexane (104), 2.2
-bis(3'-methyl-4'-hydroxyphenyl)
4-methylpentane (129), 1,1-bis(3'
-methyl-4'-hydroxyphenyl)4-methylbutane (124), 3,3-bis(3'-methyl-4
'-Hydroxyphenyl)hexane (90), 5.5
-bis(3'-methyl-47-hydroxyphenyl)
Nonane (12B), 2-(4'-hydroxyphenyl)-2-(3'-chloro-4'-hydroxyphenyl)propane (101), 2,2-bis(3'-isopropyl-I'4'- hydroxyphenyl) propane (
97), 2,2-bis(3'-tert-butyl-
4'-Hydroxyphenyl)propane (117).

2.2-bis(3'-chloro-4'-hydroxyphenyl)propane (84), 2-(4'-2droxy-3',5'-dimethylphenyl)-2-(4'-hydroxyphenyl) Propane (127), bis(3'
-methyl-5'-ethyl-4'-hydroxyphenyl)
Methane (105), 1.1-(3'-methyl-5'-
Butyl-4'-hydroxyphenyl)butane (104)
, 2.2-bis(4-hydroxyphenyl)octane (83), bis(4-hydroxyphenylmercapto)
Methane (55), bis(4-hydroxyphenylmercapto)methane (55), 1,2-bis(4-hydroxyphenylmercapto)ethane (173), 1,3-bis(4-hydroxyphenylmercapto)propane (8)
2), 1.4-bis(4-hydroxyphenylmercapto)butane (182), 1.5-bis(4-hydroxyphenylmercapto)pentane (98), 1.6-
Bis(4-hydroxyphenylmercapto)hexane (
166), 1,3-bis(4-hydroxyphenylmercapto)acetone (74), 1,5-bis(4-hydroxyphenylmercapto)-3-oxapentane (9
3), 1.7-bis(4-hydroxyphenylmercapto)-3,5-dioxahebutane (108), 1.
8-bis(4-hydroxyphenylmercapto)-3,
6-Shioxaoctane (100), 4-benzylmercaptophenol, 4-P-chlorobenzylmercaptophenol, 4-p-methylbenzylmercaptophenol, etc.

In addition to the above-mentioned color developer, the receiving layer of the receiving sheet may contain a porous filler if necessary.

This porous filler has an oil absorption of at least 50 mA/
100 g (according to JIS K 5101 method), preferably 150 m Q /100H 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 part 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 resin.

In addition, in order to strongly bond the receptor layer to the support sheet,
A variety of conventional binders can be used.

The amount of color developer applied to the support is usually 0.1 to 25
,/rrr, preferably 0.3 to 15 g/i (based on dry solid content).

The receiving sheet of the present invention is used in combination with a transfer sheet having a transfer layer containing a leuco dye.

That is, by stacking the receptor sheet of the present invention on a transfer sheet so that the receptor layer is in contact with the transfer layer, and thermally printing from the back side of the heat-sensitive transfer sheet, a density corresponding to the printing energy is printed on the receptor sheet. A colored image can be formed.

The leuco dye used in the heat-sensitive transfer sheet may be any one that is applied to this type of heat-sensitive material, such as triphenylmethane, fluoran, phenothiazine, auramine, spiropyran, and indolinophthalide. Leuco compounds of such 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-diethylaminophenyl, 3.3-bis(P-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(P-dibutylaminophenyl)phthalide, 3 -Cyclohexylamino-6-chlorofluorane.

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-tolyluaN-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-trifluoran) (methylphenyl)
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-(o-chloroanilino)fluoran.

3-Dibutylamino-7-(o-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) fluorane, Benzoylleucomethylene blue.

6'-Chloro-81-methoxy-benzoindolino-pyrylospirane.

6'-Bromo-3'-methoxy-benzoindolino-pyrylosbilane, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide.

3-(2'-Hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-ditrophenyl)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-trifluoromethylanilino)fluoran.

3-pyrrolidino-7-(di-P-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-p-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-(p
-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-phenylphthalide.

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-anilite fluorane and the like.

To manufacture thermal transfer sheets, paper 1 synthetic paper.

A transfer layer can be formed by coating a coating solution containing a leuco dye on a support sheet such as a plastic film.The coating solution for forming the transfer layer contains a leuco dye that is firmly bonded to the support sheet. For this purpose, customary binders can be added, preferably thermoplastic or thermosetting resins having a softening point or melting point of 50 to 130 DEG C. 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, fluororesin, Examples include silicone resin, natural rubber, chlorinated rubber, butadiene rubber, olefin rubber, phenol resin, urea resin, melamine resin, epoxy resin, polyimide, and the like. When applying a coating liquid to a support sheet using these resins, a solvent coating method, a hot melt coating method, an aqueous emulsion coating method, etc. are employed.

The amount of leuco dye applied to the support sheet is usually o
, i to 20 g/i, preferably 0.3 to 10 g/i (based on dry solids).

〔effect〕

The present invention is a receiving sheet having the above structure, and when performing thermal transfer in combination with a transfer sheet, a recorded image with excellent gradation can be obtained on the receiving sheet depending on the heating energy. In addition, in the present invention, transfer sheets that develop different colors are used, and these are sequentially stacked on a receiving sheet, and the colors are developed by changing the applied energy.

Excellent gradation as shown in photos. Full color images can be obtained.

〔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 gX.

Example 1 (1) Preparation of receiving paper (A-1) 1.7-bis(4-hydroxyphenylmercapto) 3
．． 5-dioxahebutane (melting point 108°C) 30 parts Silica fine particles (oil absorption 200m Q/100H)
After dispersing a composition consisting of 10 parts vinyl chloride/vinyl acetate copolymer resin 5 parts methyl cellosolve 155 parts for 24 hours using a ball mill,
It was coated on the surface of high-quality paper (64 g/n?'') using a wire bar and dried to form a high-temperature melting color developer-containing layer (lower layer) with a coating weight of 5 g/n?.

Next, on the lower layer, a solution of the following composition dispersed in 100 parts of water was applied with a wire bar and dried to form a low-temperature melting color developer-containing layer (upper layer) with a dry coverage of 1/2. A receiving sheet (A-1) was prepared.

4-Hydroxybenzoic acid butyl ester 10 parts (melting point 71°C) Silica fine particles (oil absorption 200 mm /100 g)
3 parts polyvinyl alcohol
1 part (2) Preparation of transfer sheet (B-1) 3-(N-ethyl-N-n-7 mil)amino-6-methyl-7-anilite fluorane 20 parts Polyester resin 3 parts Methyl ethyl ketone
A thermal transfer sheet (B-1) having a dry adhesion weight of 0.5 g/nf was prepared by applying 70 parts of the composition onto the surface of a polyester film having a thickness of 6 μm using a wire bar and drying it.

Next, the receiving layer of the receiving paper (A-1) obtained as described above and the transfer layer of the transfer sheet (B-1) are superimposed, and the heating energy is changed from the back side of the transfer sheet using a thermal head. When an image was recorded using the same method, a gray to black image was recorded on the receiving paper as shown in Table 9.

Table 1 From Table 1, it can be seen that when the receiving paper of the present invention is used, the image density changes in accordance with the change in heating energy, making it possible to record gradation.

Example 2 (1) Preparation of receiving paper (A-2) In the receiving paper (A-1), 1,7-bis(4-hydroxyphenylmercapto)-3,5-dioxahebutane was replaced with A high-temperature melting color developer-containing layer (lower layer) was formed in the same manner except that 5-bis(4-hydroxyphenylmercapto)-3-oxapentane (melting point: 93°C) was used.

Next, in the same manner, a low-temperature melting color developer-containing layer ( upper layer) and receiving paper (A
-2) was created.

Next, the receiving layer of the receiving paper (A-2) obtained as described above and the transfer layer of the transfer sheet (B-1) shown in Example 1 were superimposed, and the same procedure as in Example 1 was carried out. When an image was recorded using this method, a gray to black image was recorded on the receiving paper as shown in Table 2 below, demonstrating that gradation image recording was possible.

Table 2 Comparative Example 1 (1) Preparation of receiving paper (C-1) Receiving paper (C-1) was prepared in the same manner as in receiving paper (A-1) except that the high temperature melting color developer layer (lower layer) was removed. C-1)
It was created.

Next, the receiving layer of the receiving paper (C-1) obtained as described above and the transfer layer of the transfer sheet (B-1) shown in Example 1 were superimposed, and an image was recorded in the same manner as in Example 1. When I did:
In this case, as shown in Table 3 below, an image without gradation was recorded on the receiving paper.

Table-3

Claims (1)

[Claims] (1) Used in combination with a transfer sheet having a transfer layer containing a leuco dye, having a receiving layer consisting of a lower layer (A) and an upper layer (B) containing a color developer for the leuco dye; A receiving sheet for thermal transfer, wherein the upper layer (B) has a lower melting temperature than the lower layer (A).