JP2686620B2 - Chromogenic recording material - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a color-forming recording material, and pressure-sensitive copying using an indolyl methane compound which is colorless or only slightly colored as a reactive dye. The present invention relates to a color forming recording material such as paper and thermal recording paper.

[Conventional technology and problems to be solved by the present invention]

Conventionally, as reactive dyes, for example, 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (commonly called crystal violet lactone, hereinafter referred to as CVL), 3-diethylamino-6-methyl-7-anilino. Many such as fluoran are known. These develop color when they are brought into close contact with an electron-donating substance (hereinafter referred to as a developer) in a pressure-sensitive copying or heat-sensitive recording system. However, these color-developed images were markedly discolored when left in the sun and on a desk, and often became unreadable during storage. Conventionally, for the purpose of preventing this discoloration, benzoyl leuco methylene blue (hereinafter referred to as BLMB), Japanese Patent Publication No. 56-12
The compound described in Japanese Patent No. 515 N-butyl-3- [bis {4-
Although a few compounds such as (N-methylanilino) phenyl} methyl] carbazole are used in combination due to their properties of slow color development but relatively high light fastness, they are not necessarily used in terms of their color development and hue. I was not satisfied.

The present invention has been made in view of the above-mentioned prior art, and provides a reactive dye that clearly develops color when intimately contacted with a color developer and has a colored image with high light fastness.

[Means for solving the problem]

We have general formula (1) (In the formula, R ¹ and R ² are a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and the ring A is a methyl group, an ethyl group or a phenyl group having 1 to 3 alkoxy groups having 1 to 5 carbon atoms. .Less than,
The same symbols have the same meaning. It was found that the indolyl methane compound represented by the formula (1) gives a clear and highly lightfast hue in close contact with a color developer.

The indolylmethane compound represented by the general formula (1) is synthesized by the following method. That is, the diphenylamine derivative represented by the general formula (2) and the 3-formyl-2-phenylindole derivative represented by the general formula (3) are used without solvent or in an organic solvent such as methanol, ethanol, benzene, or toluene with hydrochloric acid or sulfuric acid. , Phosphorus oxychloride, p-toluenesulfonic acid and the like in the presence of an acid catalyst to obtain dehydration condensation.

When the compound of the present invention is used, a method described in the specifications of US Pat. Nos. 2,800,458 and 2,806457 may be used as a method for producing pressure-sensitive copying paper. Further, as a method for producing a heat-sensitive recording paper, for example, there is a method described in Japanese Patent Publication No. 45-14039.

The indolylmethane compound of the present invention can be used alone or in combination of two or more. Other known reactive dyes such as phthalide compounds such as CVL, 3-diethylamino-6-methyl-7-anilinofluorane, 3-
Diethylamino-7-dibenzylaminofluorane, 3-
It may be optionally mixed with various fluorane compounds such as cyclohexylamino-6-chlorofluorane and 3-ethyltolylamino-7-methylfluorane.

[Operations and Effects of the Invention] The compound represented by the general formula (1) of the present invention is used for pressure-sensitive copying paper, heat-sensitive recording paper and the like, and when it is brought into intimate contact with a color developer, it produces a clear and clear blue color. Or develops a blue-purple color. The color image has extremely excellent properties not found in the conventionally known reactive dyes. This is one of the novel indolylmethane compounds of the present invention 1.
-Methyl-2-phenyl-3- [bis {4- (N-methyl-p-anisidino) phenyl} methyl] indole (hereinafter referred to as compound A) and conventionally known CVL,
BLMB, compound N-butyl-described in Japanese Patent Publication No. 56-12515
It will be clarified by comparison with 3- [bis {4- (N-methylanilino) phenyl} methyl] carbazole (hereinafter referred to as compound B).

Comparative Example Compounds A, B and CVL, BLMB were microencapsulated in the same manner as in the below-mentioned Examples to prepare pressure-sensitive copying paper. When this was brought into close contact with a paper coated with acid clay as a color developer, and a writing pressure of a ballpoint pen was applied, a color image was developed on the acid clay. Table 1 shows the results obtained by measuring the highest density of this color image and the residual ratio of the color image after sunlight irradiation (6 hours) using a Macbeth reflection densitometer RD-514 type filter ratten # 25.
Shown in

As shown in Table 1, the hue of the compound A of the present invention is a vivid blue-purple color extremely close to the most preferable CVL. It also has extremely excellent properties in terms of color density and light fastness.

(Examples, etc.)

Next, a method for synthesizing the indolylmethane compound represented by the general formula (1) of the present invention will be specifically exemplified.

Synthesis Example 1 1-Methyl-2-phenyl-3- [bis {4- (N-
Synthesis of methyl-p-anisidino) phenyl} methyl] indole.

4-methoxy-N-methyldiphenylamine 12.8 g, 3-formyl-2-phenyl-1- in 100 cc of toluene
Methylindole (7.0 g) was added and dissolved. 8.0 g of phosphorus oxychloride was added thereto, and the mixture was reacted at 50 ° C. for 2 hours. 200c of reactant
It was discharged into water of c and neutralized with caustic soda. The toluene layer was separated and concentrated, and the residue was treated with methyl alcohol (200 cc) to obtain 13.7 g (m.p. 76-82 ° C) of a powder which was lightly colored in pale yellow.

This product is a vivid blue-purple (λ
(max 595 nm).

Synthesis Example 2 1-Methyl-2-phenyl-3- [bis {4- (N-
Synthesis of methyl-2-toluidino) phenyl} methyl] indole.

2-methyl-N-methyldiphenylamine (11.8 g) and 3-formyl-2-phenyl-1-methylindole (7.0 g) were added and dissolved in 100 cc of toluene. 0.7 g of p-toluenesulfonic acid was added to this, and it reacted at 65 degreeC for 24 hours. The reaction product was discharged into 150 cc of water and neutralized with caustic soda. The toluene layer is separated and concentrated, and the residue is treated with methyl alcohol 200cc.
10.5g (m.p65-70)
° C).

This product is a vivid blue-purple (λ
developed at max 590 nm).

Hereinafter, Synthesis Examples 3 to 7 performed by the same operation are shown in Table 2. Hue represents the color developed on silica gel.

Examples of pressure-sensitive copying paper using the novel indolylmethane compound will be shown below.

Example 0.7 g of 1-methyl-2-phenyl-3- [bis {4- (N-methyl-p-anisidino) phenyl} methyl] indole of Synthesis Example 1 was replaced with 9.3 g of monoisopropyl biphenyl.
Dissolve in Separately, 2.4 g of gelatin and 2.4 g of gum arabic in water 4
Dissolve in 0cc and adjust to pH 7.0. Both solutions are mixed and emulsified with a homogenizer. Add 100cc of water to this emulsion and add 50
After stirring at ℃ for 30 minutes, about 1 cc of 10% caustic soda solution
Is added and the mixture is further stirred at 50 ° C. for 30 minutes. Then, 10% acetic acid aqueous solution is gradually added to adjust the pH to 4.5, then cooled to 5 ° C. and stirred for 1 hour. Add to this 4% glutaraldehyde aqueous solution 3.5c
C is gradually added to harden the capsule, the pH is adjusted to 6.0 with an aqueous solution of sodium hydroxide, and the mixture is stirred at room temperature for 6 hours to complete the encapsulation. This capsule dispersion liquid was coated on a paper with a wire bar and dried to obtain a coated paper. When this paper was brought into close contact with a paper coated with acid clay as a color developer, and a writing pressure of a ballpoint pen was applied, a gently clear blue-violet image was developed on the acid clay. This image showed high density and excellent lightfastness.

Claims (1)

(57) [Claims] (1) General formula (In the formula, R ¹ and R ² are a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and the ring A is a methyl group, an ethyl group or a phenyl group having 1 to 3 alkoxy groups having 1 to 5 carbon atoms. A color-forming recording material containing an indolylmethane compound represented by the formula (1) as a reactive dye.