JPH01178581A - Colorant for thermal transfer recording - Google Patents

Abstract

PURPOSE:To provide a vivid cyanic colorant excellent in transferability, tinting power and fastness, by preparing a specific indocyanine colorant. CONSTITUTION:This colorant for thermal transfer recording of formula I, wherein R1 and R2 are each H, alkyl which may be substd. with F, aralkyl, or aryl; R3 is H, a halogen atom, substd. amino; and R4 and R5 are each substd. or unsubstd. alkyl, aralkyl, or aryl, can be easily prepared by coupling a naththol of formula II with an aniline of formula III under alkaline conditions in the presence of an oxidizing agent such as silver chloride, ammonium persulfate or red prussiate. Methods of preparing a thermal transfer recording ink from this colorant include one wherein a colorant is dissolved or pulverized together with a suitable binder in a solvent with a ball mill or the like.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a cyan dye for thermal transfer recording, and more specifically, it is a cyan dye that can be used in sublimation type thermal transfer recording methods to produce a clear cyan dye with excellent transferability, colorability, and various fastness properties. The purpose is to provide a cyan color pigment.

(Prior Art) Currently, a sublimation type thermal transfer recording method has been proposed as a method for obtaining hard copies from ephemeral images of televisions, videos, styril video cameras, and the like.

In this method, a dye is sublimated by heat to form an image on a recording medium, and a heating element or a semiconductor laser is used as a heat source. Since the amount of dye sublimation transfer can be controlled by changing the energy applied to this heat source, this method is considered to be particularly advantageous for Victorian color recording with good gradation.

(Problem to be Solved by the Invention) When obtaining a full-color image by the subtractive color method, the three primary colors that are the basis of color expression are yellow, magenta, and cyan. Among these, cyan is a complementary color to red, is a clear blue-green color, and is required to have a maximum absorption wavelength of 620 to 720 nm. However, among the artificially synthesized pigments, there are few pigments with a cyan tone, and the disperse dyes currently used for thermal transfer do not have a true cyan hue, but reproduce colors when mixed with yellow and magenta pigments. inferior in gender.

In addition, with recent advances in recording methods, there is a need for materials that can support high-speed recording and that can provide clear images with sufficient density at low energy levels.In this respect, the currently used disperse dyes does not have satisfactory performance.

In view of this situation, and in order to solve the problems of the conventional technology, the inventor of the present invention conducted extensive research and found that indonaphthol dyes have extremely excellent sublimation properties and exhibit a clear cyan color, and that indonaphthol dyes have excellent sublimation properties and exhibit a clear cyan color, and yellow and magenta dyes. They discovered that it shows excellent color reproducibility when mixed with, and completed the invention.

(Means for Solving the Problems) That is, the gist of the present invention is a dye for thermal transfer recording represented by the general formula (1).

The dye represented by general formula (1) can be prepared by a known method, for example,
- Naphthols and general formula (I
It can be easily produced by oxidative coupling with the anilines represented by II) in the presence of an oxidizing agent such as silver chloride, ammonium persulfate, or red blood salt in an alkaline environment.

R1 and R2 in the above-mentioned formula (I) are hydrogen atoms, linear or branched alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, bexyl, and octyl groups. , fluorine-substituted alkyl groups such as trifluoromethyl group, perfluoroethyl group, perfluoropropyl group,
Examples include aralkyl groups such as benzyl group and phenethyl group, and aryl groups such as phenyl group, tolyl group, halogenophenyl group, and alkoxyphenyl group.

Examples of R1 include hydrogen atoms, halogen atoms such as fluorine and chlorine, substituted amino groups such as acetamido groups, benzenecarbonamide groups 1, methoxycarbonamide groups, methanesulfonamide groups, benzenesulfonamide groups, and methylureido groups. .

Further, R9 and R5 include alkyl groups such as methyl, ethyl, propyl, and butyl groups, alkoxyalkyl groups such as methoxyethyl and ethoxyethyl groups, and hydroxyalkyl groups such as hydroxyethyl and β-hydroxypropyl groups. , halogenoalkyl groups such as chloroethyl groups, cyanoalkyl groups such as cyanomethyl groups and cyanoethyl groups, aralkyl groups such as benzyl groups and phenethyl groups, and aryl groups such as phenyl groups, tolyl groups, halogenophenyl groups, and alkoxyphenyl groups. It will be done.

A method for producing a thermal transfer recording ink using the dye of the present invention includes a method in which the dye is dissolved or atomized using a ball mill or the like in a solvent together with a suitable binder to form an ink. Examples of the binder include epoxy resin, phenol resin, urethane resin, acrylic resin, silicone resin, cellulose resin, polyvinyl chloride, polyethylene, polystyrene, polycarbonate, polyester, polyimide, polyvinyl butyral, gum arabic, and casein. Solvents include water, alcohols such as methanol, ethanol, propatool, and butanol, aromatic hydrocarbons such as toluene, xylene, and monochlorobenzene, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, dichloroethane, trichloroethylene, and perk. Examples include halogenated hydrocarbons such as oleethylene, esters such as ethyl acetate and butyl acetate, and cellosolves such as methyl cellosolve and ethyl cellosolve.

In addition, as a transfer method, the ink obtained above is applied onto a suitable substrate using a bar coater to create a transfer sheet, the sheet is overlapped with the recording medium, and then heated from the front side of the sheet with a heating element etc. There is a method to transfer the dye on the sheet onto the recording medium. Generally, capacitor paper, cellophane paper, or a plastic film with good heat resistance such as polyimide resin or polyester resin is suitable as the transfer substrate. Plain paper can also be used as the recording medium, but in order to increase color development, paper coated with polyester resin or polyamide resin, or synthetic paper such as polypropylene, polyvinyl chloride, or polyester is used. be done.

Since the dye of the present invention has a bright cyan color, it is suitable for obtaining a full color by combining with, for example, a magenta dye represented by the following structural formula and a yellow dye represented by the following structural formula.

(Effects of the Invention) According to the present invention, by using an indonaphthol dye which is shown in -Ceremony CI) and has good sublimation properties, a bright cyan-colored thermal transfer record can be obtained.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but these Examples do not limit the present invention.

Example 1 (a) Production of dye 28.0 g of silver nitrate is dissolved in 180 d of water, and sodium chloride Log is added to the aqueous solution and stirred.

Thereafter, 4.6 g of a compound represented by the following structural formula dissolved in ethyl acetate was added. Next, 20 m2 of ammonia water was added, and 5.8 g of a compound represented by the following structural formula was dissolved in 6 Qml of water, and the solution was added dropwise.

After completion of the dropwise addition, the reaction was allowed to proceed at room temperature for 1 hour, after which the inorganic substances were filtered off, the liquid was separated, and the solvent of the organic layer was distilled off. 6.0 g of indonaphthol dye was obtained. The maximum absorption wavelength (ethyl acetate) of the main island was 671 nm.

(b) Preparation of ink mobi transfer sheet dye (indonaphthol dye obtained in (a) above)
4 parts, 8 parts of ethyl cellulose and 4 parts of methyl ethyl ketone.
After thoroughly kneading an ink composition containing 4 parts of toluene and 44 parts of toluene using a ball mill, the ink composition was coated on condenser paper using a bar coater and dried to obtain a transfer sheet.

(c) Transfer recording Recording was performed by placing this transfer sheet facing high-quality paper coated with polyester resin and heating it using a thermal head, and a clear cyan-colored high color density record was obtained.
.

Examples 2 to 13 The dyes shown in Table 1 were synthesized in the same manner as in Example 1, and thermal transfer was performed in each case to obtain a clear cyan color record with high color density.

Claims (1)

[Claims] General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R_1 and R_2 each represent an alkyl group, an aralkyl group, or an aryl group that may be substituted with a hydrogen atom or fluorine, R_3 represents a hydrogen atom, a halogen atom, or a substituted amino group, and R_4 and R_5 each represent a substituted or unsubstituted alkyl group, an aralkyl group, or an aryl group. ] A dye for thermal transfer recording represented by.