JPH06145540A - Colorant for thermal transfer and thermal transfer sheet - Google Patents

Abstract

PURPOSE:To provide a thermally transferable yellow colorant having improved transfer sensitivity excellent in all of the properties, and comprising a specified quinophthalone compound. CONSTITUTION:A quinophthalone colorant of the formula wherein R<1> is lower alkyl; X is H or halogen; Y is H, -COOR<2> or-CONR<3>R<4>; and R<2>, R<3> and R<4> are each alkyl, alkoxyalkyl, cycloalkyl, allyl, aralkyl, furfuryl or tetrahydrofurfuryl is provided. A thermal transfer sheet is obtained by forming a layer of colorant comprising the above quinophthalone colorant and a binder comprising a resin on a substrate. This sheet can give a highly dense clear yellow recording of very good light fastness at low energy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive transfer dye for use in heat-sensitive transfer recording, particularly dye transfer type heat-sensitive transfer recording, and a heat-sensitive transfer recording sheet using the dye.

[0002]

2. Description of the Related Art A dye-transfer type heat-sensitive transfer recording is a heat-sensitive transfer sheet in which a heat-sensitive transfer sheet having a color material layer containing a heat transferable dye on a base film and an image-receiving sheet having a dye-receiving layer on the surface are superposed. Is a recording method in which the dye in the heat-sensitive transfer sheet is transferred to the image-receiving sheet by heating to record. This recording method is applied to full-color image recording such as a video printer because the transfer amount of the dye can be controlled by the amount of heating energy and gradation can be expressed.

In the dye transfer type thermal transfer recording, the dye used in the transfer sheet and the ink composition for the transfer sheet has a great influence on the speed of the transfer recording, the image quality of the recorded matter, the storage stability and the like, which is very important. Therefore, it is necessary to satisfy the following conditions. Easily sublimate and / or diffuse heat under the operating conditions of the thermal recording head. Do not thermally decompose under the operating conditions of the thermal recording head. It should have a favorable hue for color reproduction. Large molecular extinction coefficient. Stable against heat, light, moisture, chemicals, etc. Easy to synthesize. Excellent ink suitability. There is no problem in safety.

A dye satisfying all of the above conditions has not been found so far, and in particular, a yellow dye has various drawbacks and none is satisfactory. As a yellow dye, conventionally, quinophthalone dyes having the same basic skeleton as the dye used in the present invention have excellent properties. JP-A-60-53565, JP-A-63-182193, and JP-A-63-189289. Etc. However, the dyes shown in these are not yet sufficient especially in terms of transfer sensitivity.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a yellow dye which is a quinophthalone type dye having a transfer sensitivity which is particularly improved as compared with a conventional product and which has excellent properties in all properties, and a heat-sensitive transfer sheet using the same. It is a thing.

[0006]

The present invention provides a quinophthalone dye represented by the general formula (I) described in claim 1 and a base material, and a binder and a coloring material layer containing the quinophthalone dye. A heat-sensitive transfer sheet having the above is a gist of the present invention. Hereinafter, the present invention will be described in detail.

The quinophthalone dye represented by the general formula (I) of the present invention can be produced by a conventionally known method. The dye represented by formula (I) of the present invention will be described in detail. In the formula, the lower alkyl group represented by R ¹ is a C _{1 to} C ₄ linear or branched alkyl group. , Specifically, a methyl group, an ethyl group,
(N) -propyl group, (i) -propyl group, (n) -butyl group, (i) -butyl group and the like. R ² ,
The alkyl group represented by R ³ and R ⁴ includes C _{1 to} C ₁₂
And a linear or branched alkyl group.
As the alkoxyalkyl group represented by R ² , R ³ and R ⁴ , a 2-methoxyethyl group, a 2-ethoxyethyl group,
2- (n) propoxyethyl group, 2- (iso) propoxyethyl group, 2- (n) butoxyethyl group, 2- (i
so) butoxyethyl group, 2- (sec) butoxyethyl group, 2- (n) pentyloxyethyl group, 2- (n)
Hexyloxyethyl group, 2- (n) octyloxyethyl group, 2- (2'-ethylhexyloxy) ethyl group, 1-methyl-2-methoxyethyl group, 1-methyl-
2-ethoxyethyl group, 1-methyl-2- (n) propoxyethyl group, 1-methyl-2- (iso) propoxyethyl group, 1-methyl-2- (n) butoxyethyl group,
1-methyl-2- (iso) butoxyethyl group, 1-methyl-2- (n) hexyloxyethyl group, 1-methyl-2- (2'-ethylhexyloxy) ethyl group, 3-
Examples thereof include a methoxybutyl group, a 3-ethoxybutyl group, a 1-ethyl-2-methoxyethyl group, a 1-ethyl-2-ethoxyethyl group, and a C ₃ -C ₈ β-alkoxyethyl group is particularly preferable. Examples of the aralkyl group represented by R ² , R ³ and R ⁴ include a benzyl group and a β-phenethyl group. Examples of the cycloalkyl group represented by R ² , R ³ and R ⁴ include a cyclopentyl group and a cyclohexyl group. Examples of the halogen atom represented by X include a chlorine atom and a bromine atom.

Of the groups represented by R ² , R ³ and R ⁴ , particularly preferred are C _{1 to} C ₈ alkyl groups, and particularly preferred as X are hydrogen atom and bromine atom. More specific examples of the dye represented by the general formula (I) include:
The ones shown in Table 1 are mentioned.

[0009]

[Table 1]

[0010]

[Table 2]

When the coloring material layer is formed on the heat-sensitive transfer sheet of the present invention by using the above-mentioned dye, the method is not particularly limited, and the dye is usually dissolved or finely dispersed in the medium together with the binder. It can be carried out by preparing an ink, applying the ink to a base film as a substrate, and drying. As the binder for preparing the ink, water-soluble resins such as cellulose-based, acrylic acid-based, starch-based, epoxy-based and acrylic resins, methacrylic resins, polystyrene, polycarbonate, polysulfone, polyether sulfone, polyvinyl butyral, ethyl cellulose , Acetyl cellulose, polyester,
Examples thereof include resins soluble in organic solvents such as AS resins and phenoxy resins.

As a medium for preparing the ink, in addition to water, alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol and isobutyl alcohol, cellosolves such as methyl cellosolve and ethyl cellosolve, and aromas such as toluene, xylene and chlorobenzene. Group, esters such as ethyl acetate and butyl acetate, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, methylene chloride,
Chlorine-based solvents such as chloroform and trichlorethylene,
Ethers such as tetrahydrofuran and dioxane,
Examples thereof include organic solvents such as N, N-dimethylformamide and N-methylpyrrolidone.

In addition to the above components, organic or inorganic non-sublimable fine particles, a dispersant, an antistatic agent, an antifoaming agent, an antioxidant, a viscosity modifier, etc. are added to the above ink. I can do things. As the base film for applying the ink for producing the transfer sheet, condenser paper, thin paper such as glassine paper, polyester, polycarbonate, polyamide, polyimide, a film of good heat resistance plastic such as polyaramid is suitable. The thickness thereof can be in the range of 3 to 50 μm.

Of the above base films, the polyethylene terephthalate film is particularly advantageous in consideration of mechanical strength, solvent resistance, economy and the like. However, in some cases, the polyethylene terephthalate film does not always have sufficient heat resistance and the running performance of the thermal head is insufficient, so that the heat resistance including lubricant, heat-resistant particles with high lubricity, etc. on the opposite surface of the color material layer. By providing a resin layer, a thermal head having improved running properties can be used.

As a method for applying the ink to the base film, a gravure coater, a reverse roll coater,
It can be carried out using a rod coater, an air doctor coater, etc., and the thickness of the ink coating layer is 0.1 after drying.
It may be applied in a range of up to 5 μm. Further, 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. Further, it can be used as an electrically conductive dye transfer sheet by using an electrically conductive heat-generating film that generates heat by applying electricity to the base film itself.

[0016]

EXAMPLES The present invention will be described in detail below with reference to examples, but the examples are not intended to limit the present invention. Example 1

Table 3 a) Preparation of inks Table 1 Dye NO. 16 g Cellulose acetate (Product name: L-30; product of Daicel Chemical Co., Ltd.) 10 g Methyl ethyl ketone 80 g Total 96 g A mixture having the above composition was treated with a paint conditioner for 10 minutes to prepare an ink.

B) Preparation of transfer sheet Polyethylene terephthalate film (6 μm) whose back surface is heat-resistant and slip-treated with a wire bar is used.
(Thickness) and then dried (dry film thickness: about 1 μm) to obtain a transfer sheet. In addition, the polyethylene terephthalate film is subjected to the heat-resistant lubricity treatment by applying the following formula to the polyethylene terephthalate film.

[0018]

[Chemical 2]

8 parts by weight of a polycarbonate resin having a repeating structural unit represented by: 1 part by weight of a phosphoric acid ester type surfactant (product name: Plysurf A-208B; a product of Dai-ichi Kogyo Seiyaku Co., Ltd.), 91 parts by weight of toluene. Was applied and dried (dry film thickness: about 1 μm).

C) Preparation of image receptor Vinyl chloride-vinyl acetate copolymer resin (Product name: VYH
D: Union Carbide product) 10 parts, amino-modified silicone (product name: KF-393; Shin-Etsu Chemical Co., Ltd. product) 0.5 part, methyl ethyl ketone 15 parts, xylene 15 parts, a synthetic paper (product name: YUPO) FPG15
0: product of Oji Yuka Co., Ltd.) with a wire bar, dried (dry film thickness: about 5 μm), and further treated in an oven at 80 ° C. for 30 minutes.

D) Transfer recording The ink coated surface of the transfer sheet was superposed on the image receptor, and recording was performed using a thermal head under the following conditions to obtain a yellow recorded product having a color density shown in Table 2.

[Table 4] Recording conditions Recording density in main scanning and sub-scanning: 6 dots / mm Recording power: 0.21 W / dot Energizing time: 10 ms Color density was measured using a Macbeth Densitometer TR-927. did.

E) Light fastness test A light fastness test of the obtained recorded matter (having a color density of about 1.0) was carried out using a xenon lamp fade meter (manufactured by Suga Test Instruments Co., Ltd.) (black panel temperature: 63 ±
2 ° C), degree of discoloration and fading of recorded matter after irradiation for 80 hours {ΔE
(L ^* a ^* b ^* )} is shown in Table 2.

Examples 2 to 10 The dyes shown in Table 2 below were used in place of the dyes used in Example 1, and the same method as in Example 1 was used to prepare ink, transfer sheet, and image receptor. Transfer recording and light fastness tests were conducted and the results shown in Table 2 were obtained.

Comparative Examples 1 to 4 Instead of the dye used in Example 1, dyes (A) of the following formulas
Ink preparation, transfer sheet preparation, image receptor preparation and transfer recording, and light fastness test were conducted in the same manner as in Example 1 except that (D) to (D) were used, and the results shown in Table 2 were obtained.

[0025]

[Chemical 3]

The dye used is Dye A (JP-A-60-
53565: Dye of Example 1), Dye B (JP-A-60-
53565: Dyes of Example 2-3), Dye C (Japanese Patent Laid-Open Publication No. Sho 6)
3-182193: Dye of Example 1) and Dye (JP-A-63-189289: Dye of Example 1).

[0027]

[Table 5]

Example 11 Using the ink prepared by the following method instead of the ink used in Example 1, a transfer sheet was prepared, an image receptor was prepared and transferred, and a light resistance test was conducted in the same manner as in Example 1. As a result, it was possible to obtain a record of clear yellow and uniform color density. The light resistance of the obtained recording and the storage stability of the transfer sheet in the dark were both good.

[0029]

[Table 6] Preparation of Ink Dye Same as in Example 1 6 g AS Resin (Product Name: Denka AS-S; Denki Kagaku Kogyo KK) 10 g Toluene 70 g Cyclohexanone 10 g Total 96 g

[0030]

When the heat-sensitive transfer sheet of the present invention is used,
It is possible to obtain a clear yellow recorded matter having a high density with low energy, and further the light resistance of the obtained recorded matter is very good.

Claims (2)

[Claims] 1. A compound represented by the general formula (I): (In the formula, R ¹ represents a lower alkyl group, X represents a hydrogen atom or a halogen atom, Y represents a hydrogen atom, —COO.
It represents a group R ² or -CONR ³ R ⁴ group. R ² ,
R ³ and R ⁴ represent an alkyl group, an alkoxyalkyl group, a cycloalkyl group, an allyl group, an aralkyl group, a furfuryl group or a tetrahydrofurfuryl group), and a quinophthalone dye for heat-sensitive transfer. 2. The general formula (I) according to claim 1 on a substrate.
A heat-sensitive transfer sheet having a coloring material layer containing a binder made of a quinophthalone-based dye and a resin.