JPS61242873A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To provide a thermal transfer recording medium having excellent heat sensitivity and capable of giving transferred images with high density which are free of stickiness and have excellent gradation expression, by providing a transfer sheet having a transfer layer comprising a leuco dye and a phonolic resin as main constituents and receiving sheet having a receiving layer comprising a leuco dye and a color developer as main constituents. CONSTITUTION:The transfer sheet is provided, on a base such as a plastic film, with the transfer layer comprising a leuco dye and a phenolic resin as main constituents. The phenolic resin has the capability of developing the color of the leuco dye, is favorably adhesive to the base, and is used in an amount of 0.1-2pts.wt. per 1pts.wt. of the leuco dye. The receiving sheet having the receiving layer comprising a color developer is laid on the transfer sheet so that the transfer layer makes contact with the receiving layer, and heating is conducted on the back side of the transfer sheet while varying the heating energy, whereby the transfer layer is melted, and is transferred onto the receiving sheet, 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 having a leuco dye layer and a receiving sheet having a color developer layer, but in this case, although the gradation expression is good, it is still not fully satisfactory. It also had the disadvantage that it could not be used as kimono, and the image density was low and clear transferred images could not be obtained. Furthermore, there was a drawback that the resulting transferred image was sticky.

(Objective) An object of the present invention is to provide a thermal transfer recording medium that has excellent thermal sensitivity, provides a transferred image with high density, no stickiness, and excellent gradation expression.

〔composition〕

According to the present invention, it is characterized by comprising a transfer sheet having a transfer layer containing a leuco dye and a phenol resin as main components, and a receiving sheet having a receiving layer containing a color developer for the leuco dye as a main component. A thermal transfer recording medium is provided.

In the present invention, the transfer layer can be configured as a single leuco dye layer that provides a monochrome image, or can also be configured with a plurality of leuco dye layers 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 these four leuco dye layers, seven full colors can be easily obtained6. In other words, each color can be produced by using a single leuco dye layer that develops yellow, magenta, cyan, and black. In addition, the combination of a leuco dye layer that produces yellow and a leuco dye layer that produces magenta produces red, and the combination of a leuco dye layer that produces yellow and a leuco dye layer that produces cyan produces green and cyan. A blue color can be obtained by combining a leuco dye layer that develops a color and a leuco dye layer that develops a magenta color. In particular, multi-colored thermal transfer sheets can be easily produced by using various leuco dyes as inks and coating them on a support (e.g., paper 1 synthetic paper, plastic film, etc.) by letterpress printing or gravure printing. can be created. An example of such a heat-sensitive transfer sheet is shown in Japanese Patent Application No. 58-100686.

The transfer sheet used in the present invention is one in which a transfer layer containing leuco dye and phenol resin as main components is provided on a support such as synthetic paper or plastic film. 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-simethylaminophthalide.

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 present invention, the phenolic resin used for the transfer layer has color developing ability for leuco dyes, has good adhesiveness to supports such as plastic films, and is made of phenols (phenol, catechol, ethylphenol, t-butylphenol, cyclohexylphenol,
Resorcinol.

Cresol, xylenol, octyl cresol,
resorcinol, pyrogallol, t-amyl cresol, etc.) and aldehydes (formaldehyde, etc.),
When condensed with acids or alkalis, novolak-type resins are obtained, which are further treated with excess formaldehyde,
Add paraformaldehyde, hexamethylenetetramine, etc.

It can also be made harder. When condensed using an alkali, resol, resitol, and resit are produced depending on the degree of condensation. Phenol resin can also be dissolved in a solvent such as alcohol or drying oil to form a varnish.

Furthermore, the phenolic resin used in the present invention may be a mixture of phenol resins condensed with one or more types of phenols and one or more types of aldehydes, or a mixture of two or more different phenol resins further condensed. But that's fine.

The mixing ratio of the leuco dye and phenolic resin used in the transfer layer is 1 part by weight of the leuco dye to 0.1 part of the phenol resin.
~2 parts by weight. If the amount of phenol resin is too low, the thermal sensitivity will be low, and if it is too much, a transferred image with gradation will not be obtained.

As the phenolic resin used in the present invention, 65 to 100
It is preferable to use one that melts at °C. If the melting temperature of the phenol resin is too low, the storage stability will be poor, and if it is too high, the thermal sensitivity will be reduced.

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 leuco dye and phenol resin in the transfer layer are eutectic, melted at a low temperature, transferred to the receiving sheet, and further eutectic with the color developer of the receiving sheet. This is because the uncolored leuco dye becomes completely colored.

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
00℃ or less is applicable. Specific examples of the color developer preferably applied in the present invention are shown below, and the numbers in parentheses indicate the melting point.

4-tart-butylphenol (98), 4-hydroxydiphenyl ether (84), 1-naphthol (
9g).

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-ter
t-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-art-butylphenol) (11
0), 4,4'-isopropylidene bis(2-methylphenol) (136), 4,4'-isopropylidene bis(2,6-dimethylphenol) (168),
4,4'-5ec-butylidene diphenol (11
9), 4,4'-5ec-butylidene bis(2-methylphenol) (142), 4,4'-cyclohexylidene diphenol (180), 4,4'-cyclohexylidene bis(2-methylphenol) ( 184), salicylic acid (163), salicylic acid methalyl ester (7
4), 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 (119),
5-hydroxysalicylic acid (200), 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 (200), 2,4-dihydroxyacetophenone (97), resorcinol monobenzoate (135), 4-hydroxy Benzophenone (133
), 2,4-dihydroxybenzophenone (144),
2-naphthoic acid (184), l-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 (12
0), 1.1-bis(4'-hydroxyphenyl)-
2-propylpentane (128), 1,1-bis(4
'-Hydroxyphenyl)-2-ethylhexane (8
7), 2,2-bis(4'-hydroxyphenyl)hebutane (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)penta,n(97),i,
i-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 (128), 2-(4'-hydroxyphenyl)-
2-(3'-chloro-41-hydroxyphenyl)propane (101), 2.2-bis(3'-isopropyl-4'-hydroxyphenyl)propane (97), 2
, 2-bis(3'-tart-41-hydroxyphenyl)propane (117), 2,2-bis(3'-
Chlor-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 (1
73), 1,3-bis(4-hydroxyphenylmercapto)propane (82), 1,4-bis(4-hydroxyphenylmercapto)butane (181), 1,5-bis(4-hydroxyphenylmercapto)pentane (9
8), 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)-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 amount of leuco dye and color developer is usually 0.1 to 20 g/rrr, preferably 0.3 to 20 g/rrr for each support.
It is used at a rate of about 10 g/rrr.

In the receiving sheet of the present invention, a commonly used binder is used to firmly bond and support the color developer layer to the support.
is used, but preferably has a softening point or melting point of 50 to 1
A 30°C resin is used. As such resin,
For example, 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,
Examples include natural rubber, chlorinated rubber, butadiene rubber, olefin rubber, and phenolic resin.

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 to be used is 0.000.
It is used in a range of 0.01 to 1 part by weight. This amount of resin is 0.
If the amount 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 performing thermal transfer by combining a transfer sheet and a receiving sheet, depending on the heating energy.

A recorded image with excellent gradation can be obtained on the receiving sheet. In the case of the present invention, a transferred image with excellent heat sensitivity and high sensitivity can be obtained with a small amount of energy, and the obtained transferred image is not sticky and has good releasability. In the present invention, a multicolor image can be obtained by providing a plurality of heat-sensitive transfer layers that develop different colors and sequentially stacking them on a receiving sheet to develop the colors.

〔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 (A(1)) 3-N-Methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane 10 parts Phenolaldehyde and phenolacetylene polymer 10 (Melting point 80° C.) was dissolved in 100 parts of methyl ethyl ketone.

A transfer sheet (A(1)) of the present invention was prepared by coating the surface of a polyester film with a thickness of 6 μm using a wire bar and drying to provide a transfer layer with a coating weight of 1 g/rJ.

(2) Preparation of receptor sheet (B) 2.2-bis(4'-hydroxyphenyl)heptane 20 parts Silica fine particles (
Oil absorption amount 200m fi/100g) 10
#Polyvinyl alcohol 3 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 give a dry adhesion amount of 5g/rr.
A receiving sheet (B) of r was obtained.

Example 2 (1) Creation of transfer sheet (A(2)) 3.3-bis(p-dimethylaminophenyl)-6=dimethylaminophthalide 10 parts Phenolaldehyde and phenolacetylene polymer 10. Dissolved in 100 parts of methyl ethyl ketone, applied to the surface of a 6 μm thick polyester film using a wire bar and dried to provide a transfer layer with an adhesion of 1 g/rrr to create a transfer sheet (A(2)) of the present invention. did.

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 II Phenolaldehyde and phenolacetylene polymer (melting point 80°C) 10〃■: (Magenta) dye solution 3-Diethylamino-7,8-benzfluoran 10 parts Phenolaldehyde and phenolacetylene Polymer (melting point 80℃) lQn
■: (Yellow) Dye liquid 3.6-Simethoxyfluorane 10 parts Phenolaldehyde and phenolacetylene polymer (melting point 80°C) lQn
Dissolve each dye solution in 100 parts of methyl ethyl ketone and
A color transfer sheet (A(3)) of the present invention was prepared by printing on a 6 μm thick polyester film using a color gravure printing machine and providing a transfer layer with a dry adhesion amount of 1 g/m.

Comparative Example 1 A comparative transfer sheet (C(1)) was created in the same manner as in Example 1 except that polyester resin was used instead of the phenol resin in the transfer layer coating liquid in the transfer sheet of Example 1. .

Comparative Example 2 A comparative transfer sheet (C(2)) was prepared in the same manner as in Example 1, except that vinyl acetate resin was used instead of the phenol resin in the transfer layer coating liquid in the transfer sheet of Example 1. Created.

Using each transfer sheet obtained above as a type ribbon,
Using the receiving sheet as a type sheet, the two were superimposed and an image was recorded 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, the transfer sheet of the present invention can provide a high-density transferred image with a small amount of energy, and the resulting transferred image is non-sticky, and has excellent ribbon runnability when used as a type ribbon. I understand that there is something.

Claims (1)

[Claims] (1) A thermal transfer recording medium comprising a transfer sheet having a transfer layer containing a leuco dye and a phenol resin as main components, and a receiving sheet having a receiving layer containing a color developer for the leuco dye as a main component. .