JPH0226781A - Color forming recording material - Google Patents

Abstract

PURPOSE:To enhance the light fastness and color self-developability of a developed color image by containing a specific triphenylmethane compound as a color forming reaction substance and forming a color sharply and densely by the contact of said compound with a coupler (electron acceptive substance) as a gentle blue developing leuco dye. CONSTITUTION:As a dye for a recording material such as pressure-sensitive copy paper or thermal recording paper, a triphenylmethane compound represented by formula (wherein R<1> and R<2> are H, a 1-12C alkyl group or a benzyl group, rings A-D are an alkyl group having a halogen atoms and 1-5 carbon atoms or a benzene ring) is contained as a color forming reaction substance. The triphenylmethane compound represented by the formula is only slightly colored light-yellow or brown and well dissolved in an org. solvent, for example, diarylethane, alkylnaphthalene or the like and shows almost no color self-developability and forms a blue or bluish purple color gently upon the close contact with an electron acceptive substance, for example, a coupler such as an org. acid, acidic clay, bisphenol A or the like.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a color-forming recording material, in which an electron-donating substance, which itself is only slightly colored pale yellow or ocher, is used as an electron-accepting substance. It utilizes the property of producing a deep blue color when it comes into contact with it.

Specifically, it is used for pressure-sensitive copying paper, thermal copying paper, etc.

[Prior art and problems to be solved by the present invention] Phthalide compounds and spiropyran compounds, typified by crystal violet lactone (CVL), are color-forming colorless substances that develop a blue to bluish-purple color.

Leuco dyes such as phenothiazine compounds or triphenylmethane compounds have already been put into practical use.

However, each leuco dye has its own unique coloring hue, coloring density, coloring speed, light fastness, self-coloring property, etc., so it is possible to enhance the effect by using several types of dyes in combination depending on the purpose. It is being done. For example, lystal violet lactone (CVL), a well-known blue-coloring leuco dye, has rapid color-forming properties but poor light fastness, so it is used in combination with blue-coloring leuco dyes that are slowly color-forming but have good light fastness. Benzoylleucomethylene blue (BLMB), 3
- C4,4°-bis(N-methylanilino) is a slow blue-coloring leuco dye that develops a clear and deep color when it comes into contact with a color developer (electron-accepting substance), and has excellent light fastness of the colored image. We have discovered a material with less self-coloring property and have arrived at the present invention.

[Means to solve the problem]

The inventors of the present invention have conducted intensive research to develop a color-forming recording material that has a high color density, is free from self-coloring property, and has a blue to bluish-purple color with real-image luminosity.As a result, the present inventors have newly synthesized It has been found that the triphenylmethane compound obtained is extremely useful as a dye for recording materials such as pressure-sensitive copying paper and heat-sensitive recording paper. That is, the present invention relates to a color-forming recording material containing a triphenylmethane compound represented by the following general formula (1) as a color-reactive colorless substance.

(In the formula, R' and R2 are a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a benzyl group, and one of R1 and R2 is an alkylnoS having 6 to 12 carbon atoms. A, B, C, and D are halogen atoms.

It is a benzene ring substituted with an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms and having a good 7τ. Hereinafter, the same symbols have the same meaning. ) The novel triphenylmethane compound represented by the general formula (1) is only slightly colored pale yellow or ocher, but it can be used with aqueous solvents such as diallylethane, alkylnaphthalene, hydrogenated terphenyl, alkyl It dissolves well in biphenyl, etc., shows almost no self-coloring property, and has electron-accepting substances such as organic acids, acid clay, and phenol-formalin resins.

When brought into close contact with a color developer such as a metal salt of an aromatic carboxylic acid or bisphenol A, it slowly develops a blue to bluish-purple color.

The novel triphenylmethane compound of the present invention alone has two
It can also be used in combination of more than one species. Other known color-forming recording material dyes such as 3,3-bis-(4-dimethylaminophenyl)-6-dimethylaminophthalide and di-substituted fluoran compounds such as British Patent No. 1182743
Specification of Belgian Patent No. 815291, No. 8
15294 and bisindolylphthalides such as those described in German Patent No. 2259711.

The novel triphenylmethane compound represented by Ichihime formula (1) of the present invention is synthesized by the following method. That is, the diphenylamine derivative represented by general formula (2) is p
-1 In the presence of luenesulfonic acid, phosphoryl chloride or sulfuric acid, etc., an organic solvent fM Lf alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol, and halogenated hydrocarbons such as ethylene chloride and tetrachloroethylene, etc. 3) 4 expressed as
It is obtained by a condensation reaction with a formyl diphenylamine derivative.

[Functions and effects of the invention]

The novel triphenylmethane compound according to the present invention has extremely excellent properties not found in conventional triphenylmethane compounds conventionally known as pigments for color-forming recording materials, especially pressure-sensitive copying paper and heat-sensitive recording paper. have. This is one of the novel triphenylmethane compounds of the present invention, 4,4'-bis(l-octylphenylamino)-4''-
Methylphenylaminotriphenylmethane (A), crystal high oleene raftone (CVL), a known phthalide compound, and 4,4',4''-1-lis(dimethylamino)triphenylmethane, a known triphenylmethane compound. This will be clarified by comparison with (B).

Table (1) H,C"Cl1ff H3C"'C11゜(
CVL) (B) (1) Comparative compounds (A) and (
Solubility of B) in KMC-113 (alkylnaphthalene manufactured by Kureha Chemical) and Hysol 5BS (diarylmethane manufactured by Nippon Petrochemical) at 30°C.

As shown in Table (1), the triphenylmethane compound (A) of the present invention is a compound of the known triphenylmethane compound (B
) has extremely high solubility compared to This eliminates the risk of crystal precipitation in microcapsules when making pressure-sensitive copying paper, and also reduces the amount of expensive aromatic solvents used during microencapsulation, reducing the amount of relatively inexpensive petroleum-based solvents used. This means that it can be increased and is economically advantageous.

(2) Self-coloring comparative compounds (A) and (B) 5olIg were added to KMc-113.
(Alkylnaphthalene manufactured by Kureha Chemical Co., Ltd.) 1d and laurylbenzene 4MN are dissolved, and several drops of the solution are coated on neutral paper. One of the neutral papers was left at 150°C for 20 seconds, and the other was left at 25-30"C for 2 days. The color density was measured using a Macbeth RD514 reflection densitometer. (Wratten #25 filter was used. Table (2) When a typewriter impact was applied, a blue image was obtained on the acid clay surface. Using a Macbeth RD-514 reflection densitometer (Macbeth Company M), the maximum density of the colored image was determined. When the image density residual rate after sunlight irradiation (6 hours) was measured, Table (3)
) was the result. (The filter used was Wratten #25.) As shown in Table (2), the triphenylmethane compound (A) of the present invention is a triphenylmethane compound IF.
Compared to J(B), color development on neutral paper is extremely low.

When using this as pressure-sensitive copy paper and heat-sensitive recording paper,
There is very little discoloration due to light (meaning that you can obtain white paper).

(3) Light fastness comparison Compound (A) and CVL (7 g each) were dissolved in KMC-113 (alkylnaphthalene manufactured by Kureha Chemical Co., Ltd.) 93-, microencapsulated by the method described in Example 1 below, and coated on paper. I got the top paper.

The triphenylmethane compound of the present invention (A
) has extremely less fading due to sunlight compared to CVL,
It can be seen that it is a slow blue-coloring leuco dye with excellent light fastness.

[Examples, etc.]

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

2.5 g of N-methyl-4-formyldiphenylamine in 5.6 g of N-n octyldiphenylamine.

p-Toluenesulfone fa (monohydrate'l [0.6g
, 30ji of ethyl alcohol was added, reacted at 60°C for 21 hours, added to 100d of ice water, neutralized with caustic soda,
50M1 of toluene was added and mixed well. Separate the toluene layer, add 5w1t of N,111-dimethylformamide to the residue, dissolve it, drop the solution into 200d of methyl alcohol, and filter the precipitated pale yellow product to give 4.4"- Bis(n-octylphenylamino)
-4″-methylphenylaminotriphenylmethane6.
6g was obtained. This material gradually changes to 610nm on acid clay.
It developed a blue color with a λmax of , and the color image showed strong light fastness.

Synthesis Example 2 3.7 g of Nn octyl-4-formyldiphenylamine in 3.7 g of N-methyldiphenylamine.

p-toluenesulfonic acid (monohydrate) 0.6 g,
Add 30 ai of ethyl alcohol and react at 60°C for 28 hours. The reaction product was treated in the same manner as in Synthesis Example 1 to give pale yellow 4.4"-bis(methylphenylamino)-4"-n.
5.3 g of octylphenylaminotriphenylmethane was obtained. This material gradually changes λm to 610 nm on acid clay.
It developed a blue color with ax, and the color image showed strong light fastness.

Synthesis Example 3 In 5.6 g of N-n octyl diphenylamine, 3.7 g of N-n octyl-4-formyl diphenylamine, P-
Add toluenesulfonic acid (l water 10 parts) (16 g, ethyl alcohol 30M) and react at 60°C for 32 hours. The reaction product was treated in the same manner as in Synthesis Example 1, and a pale yellow
．． 4',4'-tris(n-octylphenylamino)
4.5 g of triphenylmethane was obtained. This product gradually developed a blue color with a λmax of 610 nm on acid clay, and the developed color image showed strong light fastness.

Next, as an example of a compound in which substitutions ax, x, x, and x have been introduced into rings A, B, C, and D in general formula (1), a novel triphenyl obtained by the same method as Synthesis Examples 1 to 3 is shown. Table (4) shows a summary of the color tones developed by methane compounds in acid clay.

In order to produce pressure-sensitive copying paper using these triphenylmethane compounds, for example, known methods described in U.S. Pat. No. 2,800,458 and U.S. Pat. For example, a known method described in Japanese Patent Publication No. 45-14039 may be used. Examples of pressure-sensitive copying paper and heat-sensitive recording paper using the new triphenylmethane compound are shown below.

Example 1 (Example of pressure-sensitive copying paper) 7 parts (hereinafter expressed in parts by weight) of 4,4'-bis(n-octylphenylamino)-4''-methylphenylaminotriphenylmethane of Synthesis Example t were added to monoisopropyl Dissolve in 93 parts of biphenyl and add to this solution a solution prepared by dissolving 24 parts of gelatin and 24 parts of gum arabic in 400 parts of water and adjusting the pH to 7. Emulsify with a homogenizer, add 1000 parts of warm water and heat at 50°C for 30 minutes. After stirring, about 1 part of 10% caustic soda solution was added, and the mixture was further stirred at 50°C for 30 minutes. Then, dilute acetic acid was gradually added to adjust the pH to 4.5, and the mixture was stirred at 50°C for about 1 hour, and the mixture was stirred at 0 to 5°C. The mixture was cooled to , and further stirred for 30 minutes.

Next, 35 parts of a 4% glutaraldehyde aqueous solution was gradually added to harden the encapsulation, and the pH was adjusted to 6 with a caustic soda aqueous solution.
The encapsulation was completed by stirring at room temperature for several hours.

This capsule liquid was uniformly applied to paper using a wire bar and dried to obtain a coated paper (upper paper). When this paper is overlaid on a base paper coated with acid clay or phenol-formalin resin as a color developer and pressure from a ballpoint pen or impact from a typewriter is applied, a dark blue image gradually appears on the base paper. Ta. This image showed excellent photostability. When the same coated surface was transferred to neutral paper, almost no color developed on the neutral paper.

Example 2 (Example of thermal recording paper) 4.4′-bis(n-octylphenylamino)-4#-menalphenylaminotriphenylmethane 3 of Synthesis Example 1
Component A is obtained by mixing and grinding 0 part with 150 parts of a 10% polyvinyl alcohol aqueous solution and 65 parts of water in a ball mill for 10 hours. The particle size of the color former after pulverization was 3 to 5 microns.

On the other hand, 35 parts of bisphenol A, 150 parts of a 10% polyvinyl alcohol aqueous solution, and 65 parts of water were similarly mixed and ground in a ball mill until the particle size became 3 to 5 microns to obtain component B. Component A and 67 parts of component B were mixed and coated on high-quality paper with a wire bar so that the solid content weight after drying was 7 g/rd, and dried to obtain heat-sensitive recording paper.

This thermal recording paper turns blue when heated with a thermal pen, etc.
There was almost no self-coloring.

Claims (1)

[Claims] (1) General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^1 and R^2 are hydrogen atoms, alkyl groups or benzyl groups having 1 to 12 carbon atoms, and R^1 and ^
One of 2 is an alkyl group having 6 to 12 carbon atoms. Rings A, B, C, and D are a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkyl group having 1 to 5 carbon atoms. It is a benzene ring which may be substituted with an alkoxy group having ) A color-forming recording material characterized by containing a triphenylmethane compound represented by the following as a color-forming reaction substance.