JPS61192593A - Thermal transfer sheet for multicolor image - Google Patents

Abstract

PURPOSE:To obtain a high density sharp full color multicolor image, by providing a black high temp. meltable transfer layer containing carbon to the lower layer of one of leuco dye layers wherein a color forming combination is constituted as a repeating unit. CONSTITUTION:On the support 1 in a transfer sheet wherein a leuco dye layer part (x) forming a yellow color, a leuco dye layer part (y) forming a magenta color and a leuco dye layer (z) forming a cyan color are constituted as a repeating unit, a carbon-containing layer (a) is provided and a leuco dye layer (b) forming a cyan color is provided thereon. The m.p. of the carbon-containing layer is pref. set to temp. about 80-20 deg.C higher than that of the upper leuco dye layer. If this m.p. difference becomes too large, the thermal sensitivity of the transfer sheet is reduced and, if too small, a satisfactory sharp full color is not obtained. The m.p. of the carbon-containing layer can be adjusted by mixing a heat meltable org. compound with carbon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive transfer sheet for multicolor images having a transfer layer 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 with a different tone are provided on a support, and a receiving sheet is attached to this transfer sheet. A method of forming a transferred image on a receiving sheet by overlapping and thermal printing is known. however,
When using a transfer sheet in which a heat sublimable dye is provided on a support, the gradation expression of image density is excellent, but there are drawbacks such as low heat sensitivity and poor storage stability. On the other hand, heat-sensitive transfer sheets, which have a heat-fusible substance and pigments on a support, have excellent heat sensitivity and storage stability, but cannot express gradation of image density, so they cannot produce clear, full-color images. It is also known to use a combination of a transfer sheet having a leuco dye layer and a receiving sheet having a color developer layer; However, it is difficult to obtain multicolor images.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive transfer sheet for multicolor images that can produce high-density, clear, full-color multicolor images.

〔composition〕

According to the present invention, the leuco dye layer is used in combination with a receptor sheet having a color developer layer, and has a leuco dye layer that develops each color of yellow, magenta, and cyan for multicolor development, and the leuco dye that develops each color. A heat-sensitive transfer sheet in which a combination of layers is configured as a repeating unit, characterized in that a black high-temperature melting transfer layer containing carbon is provided below one of the leuco dye layers constituting the repeating unit. A thermal transfer sheet for multicolor images is provided.

The thermal transfer sheet for multicolor images of the present invention has a leuco dye layer on a support that develops different colors, that is, yellow, magenta, and cyan, and A transfer sheet containing a carbon-containing transfer layer is provided below one leuco dye layer of a transfer sheet in which a combination of color-producing leuco dye layers is configured as a repeating unit. It has a higher temperature melting property than that of

In the case of the present invention, the melting point of the carbon-containing layer is 80 to 20°C, preferably 60 to 3°C, higher than that of the upper leuco dye layer.
It is better to raise the temperature by about 0°C. If this difference in melting point becomes too large, the thermal sensitivity of the transfer sheet becomes low, while if this difference in melting point becomes too small, satisfactory clear full color cannot be obtained. The melting point of the carbon-containing layer can be adjusted by mixing a heat-fusible organic compound into carbon.

The thermal transfer sheet of the present invention is one in which leuco dye layers that develop different colors for multiple colors are provided on the same support.
In this case, the leuco dye layers that develop a certain color form a set, and the set is constructed as a repeating unit on the support.

The multicolor leuco dye layer used in the present invention may be of any color as long as it develops a desired color, but generally yellow,
A leuco dye layer is selected that produces two colors, magenta and cyan. By using these three leuco dye layers and the carbon-containing layer, seven full colors can be easily obtained.

In other words, the leuco dye layer that develops yellow, magenta, and cyan can be used alone to produce each color, and the combination of the leuco dye layer that develops yellow and the leuco dye layer that develops magenta produces red. A blue color can be obtained by combining a leuco dye layer that develops yellow and a leuco dye layer that develops cyan, and a leuco dye layer that develops green and cyan, and a leuco dye layer that develops magenta. Furthermore, by combining a leuco dye layer that develops a yellow color, a leuco dye layer that develops a magenta color, and a leuco dye layer that develops a cyan color, and by using the carbon-containing transfer layer of the present invention, black color development is achieved. Obtainable.

Next, the heat-sensitive transfer sheet of the present invention will be explained with reference to the drawings, and a plan view of the transfer sheet in which the leuco dye layer portion (c) that develops a cyan color is constructed in repeating units will be shown. A carbon-containing layer is provided below the cyan-colored leuco dye layer (c). That is, the cross-sectional structure of this leuco dye layer portion (c) is as shown in FIG. (b) is provided. Note that the carbon-containing layer can also be provided below another leuco dye layer. Further, the arrow shown in FIG. 1 indicates the feeding direction of the transfer sheet. Thermal transfer sheets as described above can be easily created by using each leuco dye liquid as an ink and coating it on a support (e.g., paper, synthetic paper, plastic film, etc.) by letterpress printing, gravure printing, etc. can do.

For an example of such a heat-sensitive transfer sheet, see Japanese Patent Application No. 58.
-100686.

In the carbon-containing layer provided in the thermal transfer sheet of the present invention, the carbon contained has a particle size of 0.03 μm.
It is preferable to use carbon with an oil absorption of 1000 m m /100 g or less, and examples of the thermofusible substance mixed in with the carbon include waxes or wax-like substances such as polyethylene wax and oxidized polyethylene wax. Use is preferred.

The heat-sensitive transfer sheet configured as described above is obtained by overlaying a receiving sheet having a color developer layer thereon so that the transfer layer and the receiving layer are in contact with each other, and heating the transfer sheet from the back side while changing heating energy. , with gradation depending on the heating energy.

In addition, high-density images can be obtained. That is, when the transfer layer and the receiving layer are placed in contact with each other and heating energy is applied from the back side of the transfer sheet, the leuco dye in the transfer layer and the color developer in the receiving layer are eutecticized and react to develop color. Furthermore, in the present invention, black in a multicolor image is developed by a combination of a yellow leuco dye, a magenta leuco dye, and a cyan leuco dye. During the process, the yellow leuco dye at the beginning reacts quickly with the developer, but the cyan leuco dye at the end reacts poorly with the developer, making it difficult to obtain an appropriate black color. do not have.

In the present invention, after transferring each of the above-mentioned leuco dyes, by controlling heating energy and transferring a carbon-containing colored transfer layer thereon, a high-density and clear black colored image can be obtained, and You can get clear, full-color images.

As the leuco dyes that develop yellow, magenta, and cyan colors used in the present invention, any of those conventionally used for pressure-sensitive paper and thermal paper can be used, including triphenylmethane-based, fluoran-based, and phenothiazine-based leuco dyes. ,
Auramine-based, spiropyran-based, and indolinophthalide-based agents are preferably applied. Specific examples of these leuco dyes are shown below, but of course the present invention is not limited thereto.

Yellow dye: 3.6-Simethoxyfluorane, 3-cyclohexylamino-6-chlorofluorane, 3-(ρ-dimethylaminophenyl)-3-phenylphthalide, etc.

Magenta dye: 3-diethylamino-7,8-benzfluorane, 3-
diethylamino-6-methyl-7-chlorofluorane,
3-di(l-ethyl-2-methylindole)-3-yl-phthalide, 3-diethylamino-6-phenyl-7
-Azafluoran etc.

Cyan dye: 3,3-bis(p-dimethylaminophenyl)-phthalide, 3,3-bis(p-dimethylaminophenyl)-6
-Simethylaminophthalide (also known as Crystal Violen 1-lactone), 3,3-bis(ρ-diethylaminophenyl)-6-dimethylaminophthalide, 2-bis(P-dimethylaminophenyl)methyl- 5-dimethylamino-benzoic acid, 3-(ρ-dimethylaminophenyl)-3-(p-dibenzylaminophenyl) phthalide, and the like.

Further, as the color developer used in the present invention, electron-accepting substances such as phenolic substances, organic acids or salts or esters thereof, etc. are used, and from the viewpoint of practicality, those with a melting point of 200°C or less are preferably used. Applicable. 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-Crt-butylphenolcidiphenyl ether 2-naphthol (121), methyl-4-hydroxybenzoate (131), 4-hydroxyacetophenone (109), 2,2'-dihydroxydiphenyl ether (79), 4-phenylphenol (166) )
, 4-hert. -octylcatechol (109),
2,2'-dihydroxydiphenyl (103), 4
．． 4'-methylenebisphenol (160), 2.
2'-methylenebis(4-chlorophenol) (16
4), 2,2'-methylenebis(4-methyl-6-L
crt. -butylphenol) (125), 4,4'
-isopropylidenediphenol (156), 4.4
' -isopropylidene bis(2-chlorophenol)
(90), 4,4'-isopropylidene bis(2,6-
dibromophenol) (172), 4,4'-isopropylidene bis(2-t.ert-butylphenol)
(110), 4,4'-isopropylidene bis(2-
methylphenol) (136).

4,4'-isopropylidenebis(2,6-dimethylphenol) (168), 4,4'-see-butylidenediphenol (119), 4,4'-5ee-butylidenebis(2-methylphenol) ( 142), 4
．． 41-cyclohexylidene diphenol (180),
4,4'-cyclohexylidene bis(2-methylphenol) (184), salicylic acid (163), salicylic acid methalyl ester (74), 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 (8G), 4-hydroxybenzoic acid butyl ester (71), 4-hydroxybenzoic acid isoamyl ester Ester (50), 4-hydroxybenzoic acid phenyl ester (178), 4-hydroxybenzoic acid benzyl ester (111), 4-hydroxybenzoic acid cyclohexyl ester (119), 5-hydroxysalicylic acid (2
00), 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 (107)
.

Metatoluic acid (111), paratoluic acid (181)
, orthochlorobenzoic acid (142), metaoxybenzoic acid, Q
, aromatic acid (200), 2,4-dihydroxyacetophenone (97), resorcinol monobenzoate (1
35), 4-hydroxybenzophenone (133), 2
, 4-dihydroxybenzophenone (144), 2-naphthoic acid (184), 1-hydroxy-
2-naphthoic acid (195), 3,4-dihydroxybenzoic acid ethyl ester (12g), 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), 1,1-bis(4') -hydroxyphenyl)propane (130), 1,1-bis(4'
-hydroxyphenyl)hexane (111), 1,1-
Bis(4'-hydroxyphenyl)hebutane (120)
.

1.1-bis(4'-hydroxyphenyl)-2-propylpentane (12g), 1,1-bis(4'-hydroxyphenyl)-2-ethylhexane (87), 2
,2-bis(4'-hydroxyphenyl)butane(1
01), 3,3-bis(4'-hydroxyphenyl)
Hexane (155), ■, 1-bis(3'-methyl-
4'-hydroxyphenyl)ethane (101), ■, 1
-bis(3'-methyl-47-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'-hydroxyphenyl)hexane (78), 1,1-bis(
3'-Methyl-4'-hydroxyphenyl)hebutane (85), 2-(3'-methyl-4'-hydroxyphenyl)-2-(4'-hydroxyphenyl)propane (120), 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-4'-hydroxyphenyl)nonane (12g), 2-(4'
-hydroxyphenyl)-2-(3'-chloro-4'
-hydroxyphenyl)propane (101), 2.
2-bis(3'-isopropyl-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' -
Hydroxy-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), 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 (93
), 1,7-bis(4-hydroxyphenylmercapto-dioxahebutane (108)), 1,8-bis(4-hydroxyphenylmercapto)-3,5-dioxaoctane (100), etc.

In the transfer sheet and receiving sheet used in the present invention, the leuco dye layer and/or the color developer layer are used to increase the transferred image density and to obtain a transferred image with high density and uniform density during multiple transfers. It is preferable to further contain a porous filler, if necessary. This porous filler has an oil absorption of at least 50 tan /100 g (J
IS K5101 method), preferably 150m Q
/ 100 g or more is used. The proportion of the porous filler contained in the leuco dye layer and/or color developer layer is 0.01 parts by weight per 1 part by weight of the leuco dye or color developer.
~1 part by weight, preferably 0.03 to 0.5 part 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.

,, When providing a leuco dye layer and a color developer layer on a support, the leuco dye and color developer are attached to the support.

Usually 0.1~20g/rr? ．． Preferably 0.3-1
The coating amount is 0g/I (based on dry solids). In addition, the binder for supporting the leuco dye and color developer on the support has a melting point or softening point of 50 to 130°C.
It is preferable to contain a resin which is , but in this case, either thermoplastic or thermosetting resin can be used as the resin. The resin having a melting point preferably has a melting point of 130° C. or lower in consideration of the heat resistance and heat sensitivity of the transfer sheet.

It is sufficient from the viewpoint of thermal sensitivity that the resin has a softening point of 130° C. or lower. Specific examples of such resins include the following.

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.

The resins mentioned above can be used in the form of a single polymer, a copolymer, or a mixture of a plurality of resins. The amount of this resin used is in the range of 0.01 to 1 part by weight per 1 part by weight of the leuco dye or color developer. If the amount of this resin is less than 0.01 part by weight, the layer binding force to the support will be weakened, making it impossible to support the leuco dye and color developer on the support with sufficient adhesion force. When the amount exceeds 1 part by weight, the thermal sensitivity of the product decreases and the resulting transferred image density becomes low. The amount of resin is 0.05 to 1 part by weight of leuco dye or color developer.
It is preferable to use 0.5 parts by weight in order to obtain uniform image density during multiple transfers.

In the present invention, in order to obtain a multicolor image using the heat-sensitive transfer sheet, the receiving layer of the receiving sheet is superimposed on the transfer layer surface (the surface containing the leuco dye layer) of the heat-sensitive transfer sheet, and the The heat-sensitive transfer sheet is accurately moved using the containing layer, and a heating means such as a thermal printer is used to heat print from the back side of the heat-sensitive transfer sheet, and a multicolor image is created on the receiving sheet by the reaction between the leuco dye and the color developer. All you have to do is form it.

〔effect〕

The present invention is a thermal transfer sheet having the above structure, and when performing thermal transfer in combination with a receiving sheet, a leuco dye layer that develops different colors for multicolor development of the thermal transfer sheet is applied to the receiving sheet. A multicolor image can be obtained by sequentially overlapping and developing colors, and by controlling the heating energy, the carbon-containing transfer layer provided according to the present invention is transferred, and a high-density black color is obtained. You can get clear, full-color images.

〔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) Preparation of transfer sheet (J) (Cyan) Dye liquid 3.3-Bis(p-dimethylaminophenyl)-phthalide, 5 parts Polyester resin 3 parts Methyl ethyl ketone 100 parts (Y1) (Magenta) Dye liquid 3- Diethylamino-7,8-benzfluorane 210 parts Polyester resin 3 parts Methyl ethyl ketone 100 parts (iji) (yellow) Dye liquid 3.6-Simethoxyfluorane 10 parts Polyester resin 3 parts Methyl ethyl ketone 100 parts (1v) Carbon coating liquid Carbon (grains) Diameter 0.016 μm, oil absorption 800+n
Q / 100 g) 4 parts polyethylene wax (melting point 100°C) 16 parts toluene 100 parts Using the above coating liquid, a 6 μm thick polyester film was printed using a 6-color gravure printing machine, and as shown in Fig. 1 and A transfer sheet having the structure shown in FIG. 2 was prepared. In this case, the dry coating amount of the leuco dye layer was 0.5 g/distance.

(2) Preparation of receptor sheet 2.2-bis(4'-hydroxyphenyl)hebutane 20 parts Silica fine particles (oil absorption 200 m Q /100 g)
10 parts polyvinyl alcohol
3 parts water
A composition consisting of 100 parts was dispersed for 10 hours using a ball mill, and then applied and dried using a wire bar on the surface of high-quality paper (basis weight 35 g/r+?) to obtain a receiving sheet of 5 g 1rd after dry adhesion. .

Example 2 In Example 1, as leuco dyeing of the cyan dye solution, 3
, 3-bis(P-dimethylaminophenyl)-6-dimethylaminophthalide was used as the leuco dye in the magenta dye solution, and 3-diethylamino-6-methyl-
A transfer sheet was prepared in the same manner except that 10 parts of 7-chlorofluorane and 10 parts of 3-cyclohexylamino-6-chlorofluorane were used as the yellow dye liquid.

Comparative Example 1 A transfer sheet was created in the same manner as in Example 1, except that the carbon-containing layer was not used.

The receiving sheet shown in Example 1 was placed on each of the transfer sheets obtained above, and an image was recorded from the back side of the transfer sheet using a thermal head with varying heating energy. The following table shows the density of the recorded image obtained in relation to the heating energy.

Table-1

[Brief explanation of drawings]

FIG. 1 is an explanatory plan view of the heat-sensitive transfer sheet of the present invention, and FIG. 2 is an explanatory cross-sectional view of a cyan-colored leuco dye layer portion provided with a carbon-containing layer as the lower layer. A: Leuco dye layer that develops yellow color Opening: Leuco dye layer that develops magenta C... Leuco dye layer that develops cyan l...Support, a... Carbon-containing layer b...leuco dye layer

Claims (1)

[Claims] (1) A combination of a leuco dye layer that is used in combination with a receptor sheet that has a color developer layer and that develops each color of yellow, magenta, and cyan for multicolor development, and a leuco dye layer that develops each of the above colors. is constituted as a repeating unit, characterized in that a black high-temperature melting transfer layer containing carbon is provided below one layer of the leuco dye layer constituting the repeating unit. Thermal transfer sheet for color images.