JPS61242874A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To provide a thermal transfer recording medium having excellent heat sensitivity and capable of giving thermal transfer recorded image free of stickness, by providing a transfer sheet having a transfer layer comprising a leuco dye and a wax and a receiving sheet having a receiving layer comprising a color developer a main constituent. CONSTITUTION:The transfer sheet is produced by providing an under layer comprising a wax as a main constituent on a base such as a paper, a synthetic paper and a plastic film and providing a layer comprising a leuco dye as a main constituent thereon. The wax layer functions as a favorable reaction medium for a color forming reaction between the leuco dye and a color developer, and must be melted at a temperature not higher than the melting point of the leuco dye layer. The amount of the wax layer adhered to the base is about 0.5-2g/m<2>. A receiving sheet having a receiving layer comprising a color developer is laid on the transfer sheet, with the transfer layer in contact with the receiving layer, and heating is conducted on the back side of the transfer layer while varying the heating energy, whereby the transfer layer is melted, and is transferred onto the receiving layer, thereby forming an image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thermal transfer recording medium that utilizes a color-forming reaction between a leuco dye and a color developer.

[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 thermal sensitivity and storage stability, but has the disadvantage that it is not possible to express gradation of image density.

Also, a thermal transfer sheet is known that combines a transfer sheet with a leuco dye layer and a receiving sheet with a developer layer, but in this case, although it has excellent gradation expression, the image density is low and the image is clear. This method has the disadvantage that a good transferred image cannot be obtained. Furthermore, it also has the disadvantage that the resulting transferred image becomes sticky.

〔the purpose〕

An object of the present invention is to provide a thermal transfer recording medium that has excellent thermal sensitivity and provides a thermal transfer recorded image without stickiness.

〔composition〕

According to the present invention, there is provided a transfer sheet having a transfer layer consisting of an upper layer containing a leuco dye as a main component and a lower layer containing a wax as a main component, and a receiving layer having a receiving layer containing a color developer as a main component for the leuco dye. A thermal transfer recording medium comprising a sheet is provided.

In the present invention, the leuco dye layer in the transfer sheet is
In addition to being configured as a single leuco dye layer that provides a monochrome image, it is also possible to have a configuration in which a plurality of leuco dye layers are provided on a support for multicolor development.

In the latter case, the multicolor leuco dye layer can be any layer as long as it develops the desired color, but generally a leuco dye layer that develops each color of yellow, magenta, cyan, and black is selected. . By using such four leuco dye layers, seven full colors can be easily obtained. That is, in addition to being able to obtain each color by using a leuco dye layer that develops each color of yellow, magenta, cyan, and black alone, it is also possible to obtain each color by using a leuco dye layer that develops a yellow color and a leuco dye layer that develops a magenta color. A blue color can be obtained by combining a leuco dye layer that develops red and yellow colors and a leuco dye layer that develops cyan, and a leuco dye layer that develops green and cyan colors, and a leuco dye layer that develops magenta. . In particular, multi-colored thermal transfer sheets can be easily produced by using various leuco dyes as inks and applying them onto a support (e.g., paper, synthetic paper, plastic film, etc.) using letterpress printing or gravure printing. can be created.

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

The transfer sheet used in the present invention is provided with a layer mainly composed of wax as an under layer on a support such as paper, synthetic paper, plastic film, etc.

A layer containing leuco dye as the main component is provided.

As the leuco dye in this case, any of those conventionally used for pressure-sensitive paper and thermal paper can be applied, including triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes. The following are preferably applied.

In particular, in the case of multiple colors, specific examples of leuco dyes that provide each color include the following.

Yellow dyes: 3.6-simethoxyfluorane, 3-cyclohexylamino-6-chlorofluoran, 3-(P-dimethylaminophenyl)-3-phenylphthalide, etc.

Magenta dye: 3-diethylamino-7,8-benzfluorane, 3-
diethylamino-6-methyl-7-chlorofluorane,
3-di(1-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 violet lactone), 3.3-bis(p-diethylaminophenyl)-6-dimethylaminophthalide, 2-bis(P-dimethylaminophenyl)methyl-5- Dimethylamino-benzoic acid, 3-(p-dimethylaminophenyl)-3-(p-dibenzylaminophenyl) phthalide, and the like.

Black dye: 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6
-Methyl-7-anilinofluorane, 3-diethylamino-7-piperidinofluorane, etc.

In the transfer sheet of the present invention, the wax layer used as the underlayer acts as a good reaction medium for the coloring reaction between the leuco dye and the color developer during thermal transfer, and the wax layer has a temperature at which the leuco dye layer is thermally melted. It is necessary to melt at a temperature equal to or lower than the above temperature. The amount of this wax layer attached to the support is approximately 0.5 to 2 g/%. If it is too large, a colored image with good gradation expression cannot be obtained on the receiving sheet, while if it is too small, it will not be sufficient. The effect of improving thermal sensitivity cannot be obtained.

The wax used in the present invention is a substance that is solid or semi-solid at room temperature and can form a continuous film when in the solid state, and is melted at a temperature below the melting point of the leuco dye, usually below 100°C. It refers to a substance that exhibits a low melt viscosity. Specific examples of such waxes include animal waxes such as beeswax and spermaceti, vegetable waxes such as candelilla wax, rice wax, and carnauba wax, mineral waxes such as montan wax and osikerite, and paraffin wax. , petroleum waxes such as microcrystalline wax, modified waxes that are various other wax derivatives, hydrogenated waxes such as castor wax, various long chain fatty acids and their salts, and the like.

In the heat-sensitive transfer sheet configured as described above, a receptor sheet having a receptor layer containing a color developer is stacked on top of the receptor sheet so that the transfer layer and receptor layer are in contact with each other, and heating energy is applied from the back side of the transfer sheet. When heated while heating, the transfer layer melts and is transferred to the receiving sheet to form an image. The reason why the transfer recording medium of the present invention has high sensitivity is that the wax in the transfer layer melts at a low temperature and is transferred together with the leuco dye to the developer layer of the receiving sheet, so that the leuco dye and the developer become eutectic. This is due to the complete color development of the leuco dye.

As the color developer used in the present invention, an electron-accepting substance such as a phenolic substance, an organic acid, or a salt or ester thereof is used, and from the viewpoint of practicality, preferably a melting point of 2
Temperatures below 00°C are 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-t, ert-butylphenol (98), 4-hydroxydiphenyl ether (84), 1-naphthol (98), 2-naphthol (121), methyl-4-hydroxybenzoate (131), 4-hydroxyacetophenone (109) , 2,2'-dihydroxydiphenyl ether (79), 4-phenylphenol (1
66), 4-Sert-octylcatechol (10
9), 2,2'-dihydroxydiphenyl (103)
, 4,4'-methylenebisphenol (160), 2
,2'-methylenebis(4-chlorophenol)(1
64), 2,2'-methylenebis(4-methyl-6
-tert, -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-tert-butylphenol) (110), 4,4'-isopropylidene bis(2-tert-butylphenol)
-methylphenol) (136), 4,4'-isopropylidene bis(2,6-dimethylphenol) (16
g), 4.4'-5ec-butylidene diphenol (
119), 4.4'-5ee-butylidene bis(2-
methylphenol) (142), 4,4'-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 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 (1
19), 5-hydroxysalicylic acid (200), 5-chlorsalicylic acid (172), 3-chlorsalicylic acid (1
78), thiosalicylic acid (164), 2-chloro-5-
Nitrobenzoic acid (165), 4-methoxyphenol (
53), 2-hydroxybenzyl alcohol (87),
2,5-dimethylphenol (75), benzoic acid (12)
2), orthotoluic acid (107), metatoluic acid (
111), para-toluic acid (181), orthochlorobenzoic acid (142), metaoxybenzoic acid (200), 2
, 4-dihydroxyacetophenone (97), resorcinol monobenzoate (135), 4-hydroxybenzophenone (133), 2,4-dihydroxybenzophenone (144), 2-naphthoic acid (184), 1-hydroxy-2- naphthoic acid (195), 3,4-dihydroxybenzoic acid ethyl ester (128), 3,4-dihydroxybenzoic acid phenyl ester (189), 4-hydroxypropiophenone (150), salicyl salicylate (148),
Phthalic acid monobenzyl ester (107), 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)butane (120), 1,1-bis(4'-hydroxyphenyl)
-hydroxyphenyl)-2-propylpentane (12
8), 1,1-bis(4'-hydroxyphenyl)-
2-Ethylhexane (87), 2,2-bis(4'-hydroxyphenyl)hebutane (101), 3,3-bis(4'-hydroxyphenyl)hexane (155).

1.1-His(3'-methyl-4'-hydroxyphenyl)ethane (101), 1,1-bis(3'-methyl-41-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-41-
hydroxyphenyl)-2-(4'-hydroxyphenyl)propane (120), 2,2-bis(3'-methyl-4'-hydroxyphenyl)pentane (12B),
2,2-bis(5'-methyl-4'-hydroxyphenyl)hexane (104).

2.2-bis(3'-methyl-42-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 (128), 2-(4'-hydroxyphenyl)-2-(3'-chloro-4'-hydroxyphenyl)propane (101), 2.2-bis(3'-isopropyl-4'-hydroxyphenyl)propane (97)
, 2,2-bis(3'-tert-4'-hydroxyphenyl)propane (117), 2,2-bis(3'
-chloro-4'-hydroxyphenyl)propane (8
4), 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 (82), 1,4-bis(4-hydroxyphenylmercapto)butane ( 181
), 1.5-bis(4-hydroxyphenylmercapto)pentane (98), 1.6-bis(4-hydroxyphenylmercapto)hexane (166), 1.3-bis(4-hydroxyphenylmercapto)acetone ( 7
4), 1,5-bis(4-hydroxyphenylmercapto)-3-oxapentane (93), 1,7-bis(4-hydroxyphenylmercapto)-3,5-dioxahebutane (108), 1, 8-bis(4-hydroxyphenylmercapto)-3,5-dioxaoctane (
100) etc.

In the present invention, when a transfer layer and a receiving layer are provided on each support, the leuco dye and color developer are each usually 0.1 to 20 g/n for each support. , preferably 0.3-1
It is used at a rate of about 0 g/rrr.

In the transfer sheet and receiving sheet of the present invention, a commonly used binder is used to firmly bond and support each layer to the support, but preferably a resin having a softening point or melting point of 50 to 130°C is used. It will be done. Examples of such resins include polyethylene, polypropylene, polystyrene, and petroleum resins.

Acrylic resin, vinyl chloride resin, vinyl acetate resin.

Examples include vinylidene chloride resin, polyvinyl alcohol, cellulose resin, polyamide, polyacetal, polycarbonate, polyester, fluororesin, silicone resin, natural rubber, chlorinated rubber, butadiene rubber, and olefin rubber.

The above-mentioned resins can be used in the form of a single polymer.

It can be used in the form of a copolymer or a mixture of multiple resins. In the case of a transfer sheet, 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. In the case of a receiving sheet, it is used in an amount of 0.01 to 1 part by weight per 1 part by weight of the color developer. If the amount of the resin is less than 0.01 part by weight, the layer adhesion to the support will be weakened, while if it exceeds 1 part by weight, the thermal sensitivity of the product will be reduced and the resulting transferred image density will be low.

In the present invention, in order to obtain a multicolor image using the heat-sensitive transfer sheet, the receiving layer surface of the receiving sheet is superimposed on the transfer layer surface of the heat-sensitive transfer sheet, and a heating means such as a thermal printer is used according to one color tone information.

Printing may be performed by heating from the back side of the heat-sensitive transfer sheet to form a multicolor image on the receiving sheet by the reaction between the leuco dye and the color developer.

〔effect〕

The present invention is a thermal transfer recording medium having the above structure,
When thermal transfer is performed using a combination of a heat-sensitive transfer sheet and a receptor sheet, a high-density recorded image with excellent gradation can be obtained on the receptor sheet depending on the heating energy.
Furthermore, this recorded image is not sticky and has excellent releasability during thermal printing. Furthermore, in the present invention,
By providing multiple heat-sensitive transfer layers that develop different colors and sequentially overlapping them on the receiving sheet to develop the colors,
Multicolor 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 weight.

Example 1 (1) Creation of transfer sheet (A(1)) 1.5 parts of vinyl acetate resin and 10 parts of polyethylene wax (melting point 80°C) were mixed with 100 parts of toluene, dispersed in a bot mill for 5 hours, and the resulting liquid was applied onto the surface of a 6 μm thick polyester film using a wire bar and dried to form a wax layer with a dry coating weight of 1 g/rrr.

Next, 3-N-methyl-N-cyclohexylamino-6
- 10 parts of methyl-7-anilinofluorane and 3 parts of polyester resin are dissolved in 100 parts of methyl ethyl ketone, and this solution is applied onto the wax layer using a wire bar and dried to give a dry coating weight of 1 g/ A transfer sheet (A(1)) of the present invention was prepared by providing a dye layer of rd'.

(2) Preparation of receptor sheet (B) 2.2-bis(4'-hydroxyphenyl)heptane 20 parts Silica fine particles (
Oil absorption amount 200m 4m /100g) 10n
Polyvinyl alcohol 3 parts water
1
After dispersing the composition consisting of 00 for 10 hours using a ball mill, using a wire bar, it was dispersed using high-quality paper (basis weight 35 g).
/rrr) and dried to obtain a receptor sheet (B) with a dry coating weight of 5 g/-.

Example 2 (1) Creation of transfer sheet (A(2)) 1.5 parts of vinyl acetate resin and 10 parts of polyethylene wax (melting point 75°C) were mixed with 100 parts of toluene and dispersed in a pot mill for 5 hours. was applied onto a polyester film under the same conditions as in Example 1 and dried.

A wax layer was provided.

Next, 3,3-bis(P-dimethylaminophenyl)-
10 parts of 6-dimethylaminophthalide and 2 parts of polyester resin were dissolved in 100 parts of methyl ethyl ketone, and this solution was applied on the wax layer under the same conditions as in Example 1 and dried to form a dye layer. A transfer sheet (A(2)) was prepared.

Example 3 (1) Preparation of transfer sheet (A(3)) ■: (Cyan) dye solution 3.3-bis(p-dimethylaminophenyl)-phthalide 5 parts 3.3-bis(p-diethylaminophenyl) -6-dimethylaminophthalide 5〃Polyester resin
3〃■: (Magenta) dye liquid 3-diethylamino-7,8-benzfluoran 10 parts Polyester resin 3 II■:
(Yellow) Dye Solution 3. 6-Simethoxyfluorane 10 parts Polyester Resin 3. Each of the above dye solutions was dissolved in 100 parts of methyl ethyl ketone and printed using a 6-color gravure printing machine as shown in Example 2. A color transfer sheet [A(3)] of the present invention was prepared by printing on a polyester film provided with a wax layer and providing a dye layer with a dry adhesion amount of 1 g/r&.

Comparative Example 1 A comparative transfer sheet (C) was prepared in the same manner as in Example 1 except that the wax layer was not provided in the transfer sheet of Example 1.

Using each transfer sheet obtained above as a type ribbon,
Also, use the receiving sheet as type paper.

The two were placed one on top of the other, and thermal printing was performed from the back side of the transfer sheet using a thermal head of a thermal printing typewriter by varying thermal energy. The results are shown in Table-1.

From the above results, in the present invention, a high-density transferred image can be obtained with a small amount of energy, the transferred image is not sticky, and when the transfer sheet is used as a type ribbon, excellent ribbon running properties can be obtained. I understand.

Claims (1)

[Claims] (1) A transfer sheet having a transfer layer consisting of an upper layer containing a leuco dye as a main component and a lower layer containing a wax as a main component;
A heat-sensitive transfer recording medium comprising a receiving sheet having a receiving layer containing a color developer for the leuco dye as a main component.