JPS635992A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To obtain a transfer sheet high in speed and color density, excellent in preservability of recorded images and coated uniformly with a coloring matter in a high concentration, by providing a coloring material layer containing a specified dicyanoimidazole azo coloring matter on a base film. CONSTITUTION:A coloring material layer containing a dicyanoimidazole azo coloring matter of general formula [1] is provided on a base film. In the formula, R is a cyanoalkyl, alkoxycarbonylalkyl or substd. alkoxycarbonylalkyl, each of R<1> and R<2> is an alkenyl, alkyl, aralkyl or substd. alkyl, X is hydrogen, methyl, methoxyl, formlyamino, an alkylcarbonylamino, alkylsulfonylamino or alkoxycarbonylamino, and Y is hydrogen, methyl, methoxyl or a halogen. The coloring matter of formula [1] is dissolved, or dispersed as particulates, in a solvent together with a binder to prepare an ink, which is applied to the base film, followed by drying to provide the coloring material layer on the base film.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thermal transfer sheet 1 used for sublimation type thermal transfer recording.

[Prior Art] Conventionally, there has been a demand for technology for color recording facsimile printers, copying machines, television images, etc., and electrophotography,
Color recording technologies using inkjet, thermal transfer, etc. are being considered.

The thermal transfer recording method is considered to be more advantageous than other methods because the device is easy to maintain and operate, and the device and consumables are inexpensive.

The thermal transfer method includes a melting method in which a transfer sheet in which a heat-melting 1/1 ink layer is formed on a base film is heated by a heat-sensitive head to melt the ink and transfer it onto a recording medium; Is there a sublimation method in which a transfer sheet on which an ink layer containing a sublimable dye is formed on a l\-sphere film is heated by a thermal head to sublimate the dye and transfer and record it onto a recording medium? Since this system can control the amount of sublimation transfer of dye by changing the energy applied to the thermal head, it facilitates gradation recording and is considered to be particularly advantageous for non-color recording.

In thermal transfer recording using the sublimation method, the sublimable dye used for transfer sheet 1 is very important as it has a great effect on the speed of transfer recording, the image quality of the recorded material, storage stability, etc. conditions must be met.

■ Easily sublimated under the operating conditions of the thermal recording head.

■Do not thermally decompose under the operating conditions of the thermal recording head.

■ It must have a favorable hue in terms of color reproduction.

■ Large molecular extinction coefficient.

■ Stable against heat, light, moisture, chemicals, etc.

■ Easy to synthesize.

■ Excellent suitability for ink production.

Until now, no dye has been found that satisfies all of the above conditions, and magenta dyes in particular have been found to be satisfactory, although they have various drawbacks.

[Problems to be Solved by the Invention] An object of the present invention is to provide a heat-sensitive transfer sheet using a magenta dye that satisfies all of the above conditions.

[Means for Solving Problem 1] The present invention is based on the following formula [1] (wherein, RL: L cyanoalkyl group, alkoxy group,
R1 and R2 represent an alkenylaralkyl group, a substituted alkyl group, X represents a hydrogen atom, a methyl group, a methoxy group, a formylamino group, an alkylcarbonylamino group, It represents an alkylsulfonylamino group or an alkoxycarbonylamino group, and Y represents a hydrogen atom, a methyl group, a methoxy group, or a halogen atom. The gist of the invention is a heat-sensitive transfer sheet having a coloring material layer containing a dicyanoimidazole azo dye represented by the following on a base film.

As a method for producing the above dye used in the heat-sensitive transfer sheet of the present invention, for example, the dye represented by the following structural formula [IT]? -Amino-4,5-dicyanoimidazole is diazotized according to a conventional method, and coupled with an aniline represented by the following formula [1] (wherein, X, Y, R' and R2 are the same as defined above). The azo compound represented by the following formula [IV] (wherein, X, Y, R' and R2 are the same as defined above) obtained by It can be obtained by reacting an alkylating agent represented by a chlorine atom, a bromine atom, or an iodine atom, and R is the same as defined above.

In the case of R or β-cyanoethyl group, β-(alkoxydicarbonyl)ethyl group, acrylonitrile or the following -
It can also be easily obtained by addition reaction of acrylic acid esters represented by the formula [VI] CH2=CH-C0OR3 (in the formula, R3 represents a C1 to C8 alkyl group or a C1 to C8 substituted alkyl group). Can be done.

Specific examples of the dye of formula [I] used in the present invention include those shown in Examples, but are not limited thereto.

Particularly preferably, the formula % R is a cyanmethyl group, a β-cyanethyl group, C1 to C8
represents an alkoxycarbonylmethyl group having an alkoxy group of
Represents a C7-C8 aralkyl group, a C3-C8 alkoxyalkyl group, a hydroxyl group, a C2-C8 alkyl group substituted with a halogen atom or a cyano group, where X is a hydrogen atom, a methyl group, a formylamino group, a C1 Examples include dyes representing an alkylcarbonylamino group having a C4 alkyl group, and Y or a hydrogen atom.

When applying the above dye to the thermal transfer sheet of the present invention,
An ink is prepared by dissolving or dispersing a dye in a medium together with a binder, and the ink is applied onto a base film and dried to form a color material layer on the base film.

Binders for ink preparation include water-soluble resins such as cellulose, acrylic acid, and starch, and organic resins such as acrylic resin, methacrylic resin, polysulfone, polycarbonate, polysulfone, polyethersulfone, ethylcellulose, and acedelcellulose. Examples of the solvent include water-soluble resins and the like.
In addition to water, media for ink preparation include alcohols such as methyl alcohol, isopropyl alcohol, and isobutyl alcohol, cellosolves such as methyl cellosolve and ethyl cellosolve, aromatics such as toluene, xylene, and chlorobenzene, and ethyl acetate. , esters such as butyl acetate, ketones such as acetone, methyl alcohol, methyl isobutyl ketone, and cyclohequinanone, chlorinated solvents such as methylene chloride, chloroform, and trichloroethylene, ethers such as tetrahydrofuran and dioxane, N, N-
Organic solvents such as dimethylbormamide and N-methylpyrrolidone may be mentioned.

In addition to the above ingredients, organic and inorganic non-sublimable fine particles, dispersants, antistatic agents, antiblocking agents, antifoaming agents, antioxidants, viscosity modifiers, etc. are added to the above ink as necessary. can do.

Suitable base films for applying ink for making transfer sheets include thin paper such as condenser paper and glassine paper, and films of plastics with good heat resistance such as polyester, polyamide, and polyimide.
Their thickness may range from 3 to 50 μm.

The ink can be applied to the base film using a reverse roll coater, a gravure coater, a rod coater, an air coater, etc., and the thickness of the ink coating layer after drying is 0.5 mm. It is sufficient to apply the coating so that it is within the range of 1 to 5 μm (Yuji Harasaki, Ryōshoten 1)
Published in 1979 "]-]Tinta method).

1 Effect] The dicyanoimidazole azo dye shown in the above []] used in the heat-sensitive transfer sheet of the present invention has a clear mahinta color, so color reproducibility can be improved by combining it with appropriate yellow and cyan colors. It is suitable for obtaining good full-color recordings, and since it sublimes easily and has a large molecular extinction coefficient, it is possible to obtain high-speed recordings with high color density without placing a large burden on the thermal head. Furthermore, since it is stable against heat, light, moisture, chemicals, etc., it does not undergo thermal decomposition during transfer recording, and the obtained recording has excellent storage stability. In addition, since the dye has good solubility in organic solvents and good dispersibility in water, it is easy to prepare a uniformly dissolved or dispersed ink with high concentration, and by using such ink, It is possible to obtain a transfer sheet coated with a uniformly high concentration of dye. Therefore, by using these transfer sheets, recordings with good uniformity and color density can be obtained.

The heat-sensitive transfer sheet of the present invention can utilize not only a thermal head but also infrared rays, laser light, etc. as a heating means.

[Examples] The present invention will be specifically explained below with reference to Examples, but these Examples are not intended to limit the present invention.

Example 1 a) Preparation of ink (Maximum absorption value in chloroform: 558 nm) 0 g of the above dicyanoimidazole azo dye Cellulose acetate (manufactured by Daicel Chemical Co., Ltd., L-30) 10 g Medylethyl ketone 80 (J A mixture of the above composition) Treat with paint conditioner for 10 minutes to prepare ink.

b) Preparation of transfer sheets 1~ The above ink was coated with a bar coater (RK Pr1ntcoa
The mixture was coated on a capacitor paper (10 μm thick) using t Instruments (\0.1) and dried to a film thickness of about 1 μm) to obtain a transfer sheet.

C) Transfer recording The ink-coated surface of the above transfer sheet was overlapped with the recording medium and recorded using a thermal head under the following conditions to produce a clear magenta color.
It was possible to obtain 30 records of uniform color density.

Recording conditions Linear density of main scanning and sub-scanning 28 dots/mm Recording power crab 0.25 W/dot head heating time: iomsec The recording medium was an aqueous dispersion of 34% by weight of saturated polyester (Toyobo Co., Ltd. Manufactured by the company, Pyronal MD-1
1 g
Mix the prepared liquid with polypropylene synthetic paper (200μ
bar coater (RK Pr1nt Coat
It was manufactured by applying and drying using No. 3 manufactured by Instruments Inc.

Color density was measured using a densitometer RD manufactured by Macbeth, USA.
-514 type (filter m: Utten No. 58).

A light resistance test of 151 Radar records was carried out using a carbon arc fade meter (manufactured by Suga Test Instruments Co., Ltd.).
Although the black panel temperature was 63±2°C), there was almost no discoloration or fading after 40 hours of irradiation. Furthermore, the transfer sheet and the recording were stable against heat and moisture, and had excellent storage stability in the dark.

Example 2 Ink preparation, transfer sheet production, and transfer recording were carried out in the same manner as in Example 1 using one dye shown in Table 1 instead of the dye used in Example 1. As a result, the results shown in Table 1 were as follows. We were able to obtain a clear majinta color record with the color density shown in .

The results of the light fastness test of the obtained record and the dark storage stability test of the transfer sheet and record were good.

[Effect of the invention 1 As explained above, by using the heat-sensitive transfer sheet of the present invention, clear images with high density mapinta color,
Moreover, it is possible to form a transferred image that is stable against heat and moisture and has high light resistance.

Claims (2)

[Claims] (1) The following general formula [I]▲mathematical formula on the base film,
There are chemical formulas, tables, etc.▼・・・・・・[I] (However, in the above formula, R represents a cyanoalkyl group, an alkoxycarbonylalkyl group, or a substituted alkoxycarbonylalkyl group, and R^1 and R^2 are alkenyl group, alkyl group, aralkyl group, substituted alkyl group; X represents a hydrogen atom, methyl group, methoxy group, formylamino group, alkylcarbonylamino group, alkylsulfonylamino group, alkoxycarbonylamino group; , a methyl group, a methoxy group, or a halogen atom. (2) General formula [I] described in claim (1)
In the azo dye represented by, R is a cyanomethyl group, a β-cyanoethyl group, C_1 to C
Represents an alkoxycarbonylmethyl group having an alkoxy group of _8, a β-(alkoxycarbonyl)ethyl group having an alkoxy group of C_1 to C_8, R_1 and R_2 are an allyl group, an alkyl group of C_1 to C_8, an aralkyl group of C_7 to C_8 ,C_3~C_
8 alkoxyalkyl group, a hydroxyl group, a C_2 to C_8 alkyl group substituted with a halogen atom or a cyano group, and X is a hydrogen atom, a methyl group, a formylamino group, an alkylcarbonylamino group having a C_1 to C_4 alkyl group , Y represents a hydrogen atom, and the heat-sensitive transfer sheet has a coloring material layer containing an azo dye on a substrate.