JPS62124979A - Recording material - Google Patents

Abstract

PURPOSE:To enhance the fastness of a developed color part of a recording material, by using a condensate obtained by a reaction of a specified fluoran derivative with a specified compound as a thermal color forming component. CONSTITUTION:This recording material comprises as a thermal color forming component a product of a reaction of 2mol of a fluoran compound of general formula I with 1mol of an aldehyde or ketone compound of general formula II. In the formulas, each of R1 and R2, which may be the same or different, is a 1-6C alkyl, and each of R3 and R4, which may be the same or different, is hydrogen, a 1-6C alkyl or phenyl. The condensed product is relatively low in solubility in plasticizers, oils, organic solvents or the like, so that the fastness of a developed color part of this thermal recording material is thereby markedly enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a specific fluoran derivative and an aldehyde or
The present invention relates to a recording material containing a condensation product obtained by reacting a ketone compound as a heat-sensitive coloring component.

[Conventional technology]

Heat-sensitive recording materials using electron-donating fluoran dyes and electron-accepting compounds are generally widely known (for example, Japanese Patent Publication No. 5.1-23204 and Japanese Patent Application Laid-Open No. 57-315).
91.58-52356 and 60-36568).

Such fluoran dyes include, for example, 3-N,N-noethylamino-7-o as a black chromophore.
-chloroanilinofluorane, 3-(N-methyl-N-
Examples include cyclohexylamino)-6-methyl-7-anilite fluorane.

The minimum performance that such recording materials should have is 1) sufficient color density and color development sensitivity, 2) no fogging, and 3) sufficient fastness of the color material after color development. , etc., but at present no one has been obtained that completely satisfies all of these performances.

[Problem that the invention seeks to solve]

In particular, the heat-sensitive recording paper using conventional fluoran dyes as described above has the disadvantage that the color disappears when a plasticizer, oil, organic solvent, etc. come into contact with the colored portion.

The inventors of the present invention have made extensive studies to solve the drawbacks of conventional fluoran dyes, and as a result, we have developed a thermosensitive condensation product obtained by reacting a specific fluoran derivative with an aldehyde or ketone compound. The present inventors have discovered that when used as a color-forming component, the fastness of the color-forming portion of the resulting recording material is significantly improved, leading to the completion of the present invention.

[Failure to solve the problem]

According to the present invention, the following general formula I, [in the above formula, R1
and R2 may be the same or different and each represents a C1 to C6 alkyl.] 2 moles of a fluoran compound represented by the following general formula A record characterized in that it contains as a heat-sensitive color-forming component a product obtained by reacting with 1 mole of an aldehyde or ketone compound, which may be different and each represents hydrogen, 01-C6 alkyl, or phenyl. Materials provided.

The condensation product useful in the recording material of the present invention has relatively low solubility in various plasticizers, oils, organic solvents, etc., and therefore significantly improves the fastness of the colored portion of the heat-sensitive recording material. In addition, these condensation products can be brought into close contact with electron-accepting substances (color developers), such as carbonate, bisphenol A, and silica gel, which are themselves almost white substances, to produce a good black tone. It has color-forming properties and is extremely useful as a heat-sensitive color-forming component for heat-sensitive recording materials.

In the compound of general formula I used in the present invention, R1 and R
Alkyl as 2 may be straight chain, and preferred are, for example, the following groups.

-N(CF2)2-N(C2H5)2 -N(C3H7)2-N(C4H9)2 In the synthesis of the condensation product according to the present invention, for example, 2 moles and 1 mole of the aldehyde or ketone compound of general formula (2) are mixed in acetonitrile, tetrahydrofuran, using a condensing agent such as sulfuric acid, hydrochloric acid, phosphoric acid, etc., and optionally in the presence of a catalyst such as ferric chloride, calcium chloride, etc. , in polar solvents such as dioxane, acetic acid, etc.
React for 4-150 hours at a temperature of ~80°C. Then,
By adding an organic amine such as diethylamine, triethylamine, etc. or an aqueous solution of caustic soda, pouring into neutralized drained water, separating the precipitate, and recrystallizing it from an organic solvent such as toluene, benzene, inglobil alcohol, etc. The condensation product can be obtained with high purity.

A recording material can be prepared by a known method using the resulting condensation product as a thermosensitive coloring component. For example, US Pat.
! According to the method described in 800458, a heat-sensitive recording material can be obtained using the condensation product as a coloring component.

〔Example〕

The present invention will be further explained below with reference to Examples.

[Synthesis Example 1] 3-N,N-noethylamine-7-o-chloroanilinofluorane5. Og, acetonitrile 25ml, acetic acid 1
Dissolve in 1.0ml of concentrated sulfuric acid. Add 0.13 g of paraformaldehyde and react at room temperature for 6 hours.

After the reaction is completed, 30 rttl of triethylamine is added to the reaction solution, and after neutralization, it is poured into 300 rnl of ice water, and the precipitate is filtered. Subsequently, benzene was added to perform recrystallization,
4.1 g of a white powder condensation product was obtained.

The melting point of this product was 175-181°C. Further, according to molecular weight measurement by group permeation chromatography, this product corresponded to a condensate of 2 moles of the raw material fluoran compound.

Note that this product exhibited a black edge color on silica dal, and the color developed when brought into contact with bisphenol A etc. was a black edge color.

[Synthesis Example 2] 5 g of 3-dibutylamino-7-o-chloroanilinofluorane was mixed with 5 Q ml of methyl ethyl keto, and 3 ml of concentrated hydrochloric acid.
Dissolve 0.5 ml of ferric chloride in 5 ml. ! Add i' and 50
React at ℃ for 150 hours. After the reaction is complete, pour the reaction solution into ice water.
000m/! After neutralization, the precipitate is filtered.

Next, this precipitate is dissolved in benzene and washed with a 2% aqueous sodium hydroxide solution.

Separate the benzene layer, dehydrate with anhydrous sulfuric acid, and concentrate. Subsequently, isopropyl alcohol was added to perform recrystallization to obtain 2.7 g of a white powder condensation product. The melting point of this product was 144-149°C. Also, according to molecular weight measurement using glupermeation chromatography,
This product corresponded to a condensate of 2 moles of the starting fluoran compound.

This product exhibited a black edge color on the silica shell, and the color developed when brought into contact with bisphenol A or the like was black.

[Synthesis Example 3] 5.0 g of 3-N,N-dibutylamino-7-0-chloroanilinofluorane was mixed with 20 rnl of acetonitrile and 2 ml of hydrochloric acid.
3. Dissolve in 5ml and add 10ml of benzaldehyde.
1g was obtained. The melting point of this product was 142-147°C. Furthermore, according to the molecular weight measurement by Kerbermeation chromatography, this product corresponded to a condensate of 2 moles of the raw material fluoran compound.

It should be noted that this product appeared black on a silica shell, and when brought into contact with sibisphenol A etc., the color developed was black.

[Synthesis Example 4] 5.0 g of 3-N,N-diethylamino-7-o-chloroanilinofluorane was added to 50 ml of methyl inbutyl ketone.
, concentrated hydrochloric acid 35mA! 0.5 I of ferric chloride was added, and the mixture was reacted at 50° C. for 150 hours. After the reaction is completed, the reaction solution is poured into 10,100 O of ice water, and after neutralization, ethyl acetate is added and the ethyl acetate layer is separated. Next, this ethyl acetate layer is further washed with a 2% aqueous sodium hydroxide solution. The ethyl acetate layer is separated, dried over anhydrous sodium sulfate, and concentrated. Subsequently, benzene was added to perform recrystallization to obtain 3.0 g of a white powder condensation product. The melting point of this thing is 157-16
The temperature was 2°C. Further, according to molecular weight measurement by group permeation chromatography, this product corresponded to a condensate of 2 moles of the raw material fluoran compound.

Note that this product exhibited a black color on silica gel, and the color developed when brought into contact with bisphenol A or the like was black.

[Example 1] Dispersions A and B were prepared by pulverizing and dispersing the following components using an attritor.

[Dispersion A]

Condensation product obtained in Synthesis Example 1 20 parts by weight 10%
Polyvinyl alcohol aqueous solution 20 Water
60 [Dispersion B] Bisphenol A 15 parts by weight Calcium carbonate ・5110% 71J
Vinyl alcohol aqueous solution 201I water
6 o Next, CA
Solution I, CB, and Solution I were mixed and stirred at a weight ratio of 1:5 to obtain a heat-sensitive coloring layer coating solution.

This heat-sensitive coloring layer coating liquid is applied to the surface of commercially available high-quality paper using a wire bar, dried to form a heat-sensitive coloring layer with a coating weight of 5≠3, and then calendered.
A thermosensitive recording sheet was created.

[Example 2] A heat-sensitive recording sheet was prepared in the same manner as in Example 1, except that the condensation product synthesized in Synthesis Example 2 was used instead of the fluorane condensation product in Solution A.

[Example 3] A heat-sensitive recording sheet was prepared in the same manner as in Example 1, except that the condensation product synthesized in Synthesis Example 3 was used instead of the fluorane condensation product in Solution A.

[Comparative Example 1] Instead of the fluorane condensation product of liquid A in Example 1, 3-(N-methyl-N-cyclohexylamino)-6-methyl-7-anilite fluorane, which has been widely used in the past, was used. A thermosensitive recording sheet was prepared in the same manner except that

The four types of recording materials obtained in the Examples and Comparative Examples shown above were tested in a thermal gradient tester at a temperature of 150°C and
A pressure of kfil/crn was applied for 0.5 seconds.

The surface of the colored sample was covered with a plasticizer-containing soft PVC film for food packaging, and a load of 250 fi/cm2 was applied in an environment of 30°C, and the colored image was decolored after 24 hours. was visually evaluated.

In addition, cottonseed oil was applied to the surface of the colored sample, and 3
Discoloration of the colored image after being left at 0° C. for 24 hours was visually evaluated.

The results are shown in the table below.

[Note] Plasticizer resistance, oil resistance - ○: Decoloration of the colored part is not a practical problem. It is possible to provide an extremely useful heat-sensitive recording material that has excellent fastness of the colored portion to plasticizers, oil-based organic solvents, and the like.

Claims (1)

[Claims] 1. The following general formula I ▲There are mathematical formulas, chemical formulas, tables, etc.▼... I [In the above formula, R_1 and R_2 may be the same or different, and each represents C_1 to C_6 alkyl 2 moles of a fluoran compound represented by the following general formula
II, ▲There are mathematical formulas, chemical formulas, tables, etc.▼…II [In the above formula, R_3 and R_4 may be the same or different and each represents hydrogen, C_1 to C_6 alkyl, or phenyl] A recording material comprising, as a heat-sensitive coloring component, a product obtained by reacting with 1 mole of an aldehyde or ketone compound.