JP2530187B2 - Dye for thermal transfer recording - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cyan dye for heat-sensitive transfer recording, and more specifically, in a sublimation-type heat-transfer recording method, it is excellent in transferability, colorability and various fastnesses. It is intended to provide a cyan dye.

(Prior Art) At present, a sublimation thermal transfer recording system has been proposed as a method for obtaining a hard copy from a transient image such as a television, a video, a styryl video camera.

In this method, 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 it is possible to control the sublimation transfer amount of the dye by changing the energy applied to the heat source, it is considered that the method has good gradation and is particularly advantageous for pictorial color recording.

(Problems to be Solved by the Invention) When a full-color image is obtained by the subtractive color method, the three primary colors that are the basics of color expression are yellow, magenta, and cyan. Of these, cyan is a complementary color of red, is clear blue-green, and its maximum absorption wavelength is required to be 620 to 720 nm. However, few artificially synthesized pigments have a cyan tone, and the disperse dyes currently used for thermal transfer are not true cyan in hue, but color reproduction when mixed with yellow and magenta pigments. The sex is inferior.

Further, with the recent progress of recording methods, a material capable of providing high-speed recording and providing a clear image with sufficient density at low energy is desired. In this respect as well, a disperse dye currently used. Does not have satisfactory performance.

The present inventor, in view of such a situation, in order to solve the problems of the prior art, as a result of earnest research, the indonaphthol dye is extremely excellent in sublimation, and also exhibits a clear cyan color,
They have found that they exhibit excellent color reproducibility when mixed with yellow and magenta dyes, and completed the invention.

(Means for Solving Problems) That is, the present invention provides a compound represented by the general formula [I] The heat-sensitive transfer recording dye represented by the following is the gist of the invention.

The dye represented by the general formula [I] can be obtained by a known method, for example, a naphthol represented by the general formula [II] and a general formula [II].
It can be easily produced by oxidative coupling with an aniline represented by I] in the presence of an oxidizing agent such as silver chloride, ammonium persulfate, and red blood salt in an alkaline manner.

Examples of R ₁ and R ₂ represented by the general formula [I] include a hydrogen atom, a linear or branched alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and an octyl group, and trifluoro. Methyl group, perfluoroethyl group,
Examples thereof include a fluorine-substituted alkyl group such as a perfluoropropyl group, an aralkyl group such as a benzyl group and a phenethyl group, an aryl group such as a phenyl group, a tolyl group, a halogenophenyl group and an alkoxyphenyl group.

Examples of R ₃ include a hydrogen atom, a halogen atom such as fluorine and chlorine, an acetamide group, a benzenecarbonamide group, a methoxycarbonamide group, a methanesulfonamide group, a benzenesulfonamide group, and a substituted amino group such as a methylureido group. To be

Further, R ₄ and R ₅ are an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group, an alkoxyalkyl group such as a methoxyethyl group and an ethoxyethyl group, a hydroxyethyl group and a hydroxy group such as a β-hydroxypropyl group. Alkyl group, halogen alkyl group such as chloroethyl group, cyanoalkyl group such as cyanomethyl group, cyanoethyl group, aralkyl group such as benzyl group and phenethyl group, phenyl group, tolyl group, halogenophenyl group, aryl group such as alkoxyphenyl group, etc. Is mentioned.

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

As a transfer method, the ink obtained above is applied on a suitable substrate using a bar coater to prepare a transfer sheet, the transfer sheet is superposed on the recording medium, and then heated from the back surface of the sheet with a heating element or the like. There is a method of doing so, in which case the dye on the sheet is transferred onto the recording medium. Generally, condenser paper, cellophane paper, or a plastic film having 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 paper coated with polyester resin or polyamide resin, or synthetic paper such as polypropylene, polyvinyl chloride, or polyester is used in order to enhance color development sensitivity. To be done.

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

(Effects of the Invention) According to the present invention, vivid cyan color sensitivity transfer recording can be obtained by using an indonaphthol dye represented by the general formula [I] and having good sublimation property.

Hereinafter, the present invention will be specifically described with reference to examples, but the examples do not limit the present invention.

Example 1 (a) Preparation of dye 28.0 g of silver sulfate is dissolved in 180 ml of water, and 10 g of sodium chloride is added to the aqueous solution and stirred.

Then the following structural formula dissolved in ethyl acetate 4.6 g of the compound shown by was added. Then ammonia water
Add 20 ml and then the following structural formula 5.8 g of the compound shown by was dissolved in 60 ml of water, and the solution was added dropwise. After completion of the dropwise addition, the mixture was reacted at room temperature for 1 hour, after which the inorganic substances were separated by filtration and the organic layer was evaporated to remove the solvent. Thus, 6.0 g of an indonaphthol dye represented by The maximum absorption wavelength (ethyl acetate) of this product was 671 nm.

(B) Preparation of Ink and Transfer Sheet After thoroughly kneading the ink composition of 4 parts of dye (indonaphthol dye obtained in (a) above), 8 parts of ethyl cellulose, 44 parts of methyl ethyl ketone and 44 parts of toluene with a ball mill, A transfer sheet was obtained by applying it to a condenser paper using a bar coater and drying it.

(C) Transfer recording Recording was carried out by facing this transfer sheet with a polyester resin-coated high-quality paper and heating it with a thermal head to obtain clear cyan high color density recording.

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

Claims (1)

(57) [Claims] 1. A general formula (I) The dye for heat-sensitive transfer recording shown by.