JPH0637499B2 - Pyromellitic acid derivative, method for producing the same, and recording material containing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel color forming compound, which itself is a light brown compound, but easily develops a green color by contact with an active hydrogen-containing compound, and The absorption wavelength also exists in the near infrared region, so that it can be used as a recording material.

[Conventional technology]

With the development of optical devices in recent years, dyes having absorption in the near infrared region have been demanded. It has been well known that other metal chelate compounds such as phthalocyanine and quinacridone also have absorption in the near infrared region, but these have large absorption in the visible region, so that they are limited in use in recording materials. Therefore, it has been attempted to make the dye a so-called leuco type to develop the color for the first time by contact with a color developer, for example, JP-A-51-121035, 51-121037, and 51-1.
21038, 57-167979, 58-157779 or 60-22
An example can be found in 6871.

[Problems to be solved by the invention]

When actually synthesizing the leuco-type color-forming dyes disclosed in the above-mentioned prior art documents, many of them are unstable in the compound themselves and the synthesis is difficult, or the color-forming ability is weak even if they can be synthesized,
Also, there are many drawbacks such as poor performance retention, and I have not heard of any cases where it was produced in large quantities and put into practical use. As a result of intensive studies, the present inventors have found that a compound having a structure that has never been known can be easily synthesized with high yield, and that the color former has a large absorption in the near infrared region and is useful as a recording material. And has reached the present invention.

[Means and Actions for Solving Problems]

The compound of the present invention has a structure represented by the general formula [I], which itself is usually a light brown color and can be regarded as a kind of leuco dye.

[In the formula, R ¹ and R ² each independently represent an alkylene radical selected from ethylene, propylene, and trimethylene, and among the radicals, a radical not bonded to nitrogen is a carbon atom in an ortho position with respect to the nitrogen atom on the benzene nucleus. It is bonded to an atom or is bonded to R ¹ and R ² to form a ring. When R ¹ is an alkylene group bonded to an ortho carbon atom, R ² may be a group selected from an alkyl group having 1 to 6 carbon atoms, a benzine group, and a cycloalkyl group having 5 to 7 carbon atoms. . Hereinafter, the same symbols have the same meaning. ] To prepare the compound [I] of the present invention, pyromellitic acid or its anhydride and 1,1-bis (P-
Substituted amino-phenyl) ethylene may be condensed under dehydration conditions.

1,1-bis (P-substituted amino-phenyl) ethylene [II] in place of 1,1-bis (P-substituted amino-phenyl) ethanol; Even under the dehydrated condition, it becomes the same as [II],
It is the same.

As the dehydrating agent, known ones such as various organic and inorganic acids can be used, but acetic anhydride can be most conveniently used also as a solvent. Pyromellitic dianhydride has two sets of acid anhydride structures in one molecule, but under normal condensation conditions, dehydration condensation occurs only in one side and one side remains unreacted. Therefore, the reaction product mainly has the structure represented by the formula [I] and can be obtained in a high yield.

The compound of the present invention represented by the formula (I) is a slightly light brown crystal by itself, and its solution has almost no absorption in the visible and near infrared region, but it is easily reacted with an active hydrogen compound to be visible. -It becomes a color-forming material that exhibits large absorption in the near-infrared region.
While many of the leuco color formers of this type proposed hitherto develop color upon reaction with an acid, the compound of the present invention naturally develops color upon reaction with an acid, and depending on the conditions, water It also develops on contact with alcohols, alcohols and aromatic amines.

That is, the compound of the present invention is a chromogen that is reactive with an active hydrogen compound, and there is a marked difference in color forming ability and color developing rate depending on the type of active hydrogen-containing compound that is a reaction partner. For example, when methanol is added to a toluene solution of the compound of formula [I], a green color is instantly developed, but when t-butanol is added, almost no color is observed. By utilizing such a difference in properties, it can be used in a very wide range as a recording medium, for example, a pressure-sensitive recording copy sheet, a heat-sensitive recording sheet, an optical recording laminate, a red body reader. It can be used for printing ink, temperature indicating material, etc.

〔Example〕

Synthesis example 1. 87.2 g of pyromellitic dianhydride, 1200 ml of acetic anhydride and 400 ml of tetrachloroethylene are mixed and heated to 65 ° C. Then 1,1-bis (P-pyrrolidinophenyl) ethylene 254.
After adding 4 g and stirring for 1 hour, the solid product is collected and washed with tetrachloroethylene. The excess residue is put into acetone, stirred for 30 minutes, then separated and washed again with tetrachloroethylene. Repeat the same washing operation 3 times and finally 60
Dry at ℃, 197g of light brown crystals are obtained.

Elemental analysis results (C ₅₄ H ₅₂ N ₄ O ₅ molecular weight 837.03) Melting point 220-225 ° C (decomposition) Synthetic Examples 2 to 6 The reaction is performed in the same manner as in Synthetic Example A, and the reaction solution is spread on a silica gel thin layer (developing agent toluene / ethyl acetate = 9/1). The chromogenic compound [I] shown in was confirmed as the upper color spot on the chromatogram. The spots showed maximum absorption in the near infrared region (about 850 to 880 nm) in addition to the visible region (about 670 to 700 nm) by reflection spectrum measurement.

Recording Body Manufacturing Example 1. 0.1 g of [IA] produced in Synthesis Example 1 was dissolved in 10 ml of isopropylbiphenyl, combined with 5 ml of 10% aqueous solution of 2 ml polyvinyl alcohol (polymerization degree 500), and well mixed and emulsified with a homogenizer. This emulsion is thinly coated on neutral paper using a wire bar and air dried in the dark. When the coated surface was faced to the CF paper surface (upper leaf paper upper surface) of a commercially available pressure-sensitive copying paper and pressure-bonded from the back surface, a green pressure-bonded image was obtained on the CF paper surface. When the reflection spectrum of this colored part is measured, it is 690n
It showed maximum absorption at m and 880 nm.

Recording body production example 2. 0.5 g of [IA] produced in Synthesis Example 1 and 0.5 g of 2-benzyloxynaphthalene are dissolved in 50 ml of toluene, paper is impregnated with this solution and air dried. Polyvinyl alcohol 10% in which 2 g of 2-benzyloxynaphthalene and 2 g of bisphenol A finely pulverized to have a particle size of about 2 μm are dispersed and contained.
Prepare 20 g of the aqueous solution, apply a thin coat on this paper using a wire bar, and air dry. When a temperature-variable heating plate was pressure-bonded to the obtained paper, a green pressure-bonded image was obtained at a temperature of 140 ° C or higher.

Recording body production example 3. 1 g of [IA] produced in Synthesis Example 1 and 2,2-bis (P-
Acetoxyphenyl) propane 1g and chloroform 20
It was dissolved in ml, cast on a glass plate in the dark, and dried. When the coated surface was covered with another glass plate and the sunlight focused by the convex lens was focused on the coated surface, the focal point instantly changed to green.

Recording body manufacturing example 4. 0.1 g of [IA] produced in Synthesis Example 1 is dissolved in 20 ml of toluene, mixed with 20 ml of a 10% toluene solution of polystyrene, cast on a polyester film in the dark and dried.

2- [3,4-diacetoxystyryl] quinoline 0.1 g
Is dissolved in 20 ml of toluene, mixed with 20 ml of 10% polystyrene solution in polystyrene, and cast and dried on a polyester film.

When the obtained double-layered films were superposed on each other by hot-pressing, they turned green at 140 ° C or higher. Even when sunlight was collected by a convex lens, when the focus was applied to the stacking surface, that part turned green.

〔The invention's effect〕

The compound of the present invention has a large absorption in the near infrared region; is easy to synthesize; it not only develops a color upon reaction with an acid, but also develops a color upon reacting with various active hydrogen compounds, and the kind of active hydrogen compound Therefore, it has a remarkable difference in color-forming ability and color-developing rate; and has characteristic properties such as, and is expected to be used as various recording materials.

Further, the production method of the present invention utilizes dehydration condensation of pyromellitic acid having two sets of acid anhydride structures in one molecule, and it is considered that a considerable amount of by-products are usually produced. Nevertheless, in reality, the above-mentioned target compound can be produced in high yield.

Claims (3)

[Claims] 1. A general formula Pyromellitic acid derivative represented by. [In the formula, R ¹ and R ² each independently represent an alkylene radical selected from ethylene, propylene, and trimethylene, and radicals not bound to nitrogen among the radicals are ortho to the nitrogen atom on the benzene nucleus. It is bonded to the corresponding carbon atom or is bonded to R ¹ and R ² to form a ring. When R ¹ is an alkylene group bonded to an ortho carbon atom, R ² may be a group selected from an alkyl group having 1 to 6 carbon atoms, a benzyl group and a cycloalkyl group having 5 to 7 carbon atoms. . ] 2. A general formula [I] characterized in that pyromellitic acid or an anhydride thereof is condensed with 1,1-bis (P-substituted amino-phenyl) ethylene represented by the general formula [II]. Process for producing the represented pyromellitic acid derivative. [In the formula, R ¹ and R ² each independently represent an alkylene radical selected from ethylene, propylene, and trimethylene, and radicals not bound to nitrogen among the radicals are ortho to the nitrogen atom on the benzene nucleus. It is bonded to the corresponding carbon atom or is bonded to R ¹ and R ² to form a ring. When R ¹ is an alkylene group bonded to an ortho carbon atom, R ² is a group selected from an alkyl group having 1 to 6 carbon atoms, a benzyl group, and a cycloalkyl group having 5 to 7 carbon atoms. Good. ] 3. A recording material containing a compound represented by the general formula [I] as a coloring substance. [In the formula, R ¹ and R ² each independently represent an alkylene radical selected from ethylene, propylene, and trimethylene, and radicals not bound to nitrogen among the radicals are ortho to the nitrogen atom on the benzene nucleus. It is bonded to the corresponding carbon atom or is bonded to R ¹ and R ² to form a ring. When R ¹ is an alkylene group bonded to an ortho carbon atom, R ² is a group selected from an alkyl group having 1 to 6 carbon atoms, a benzyl group, and a cycloalkyl group having 5 to 7 carbon atoms. Good. ]