JPS61229591A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain thermal recording with high color density and high sensitivity, by using a specific fluoran compound as a component for color development. CONSTITUTION:The fluoran compound shown by a general formula is used as a component for color development. The fluoran compound shown by a general formula is a solid stably colorless or slightly colored in an outer atmosphere and makes a color of the black series just after coming into contact with a conventional developer for leuco dye. The developed coloring matter is very effective as a component for color development because of its superior shelf life.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a leuco-based heat-sensitive recording material containing a fluoran compound as a coloring component.

[Conventional technology]

Fluoran compounds are used as color-forming components in leuco-based recording materials, and are also used as color-forming colors and base materials in pressure-sensitive recording paper and thermosensitive polyelectrocopy paper. There is. Another of various fluoran compounds: 52
Fluoran compounds having a (substituted phenyl)amino group at the position include Japanese Patent Publication No. 48-2406 and Japanese Patent Publication No. 48-24329.
No. 6, Special Publication No. 49-32767, Special Publication No. 51-232
04, No. 49-34526 and other publications, and the substituents include alkyl groups, alkoxy groups, halogen atoms, and carboxy groups! The fluoran compounds that are known and have been developed in the public domain are thermal recording paper, energization, *a density, background color density, J1
There are shortcomings in color starting temperature, bonding, and color development, etc.
It cannot exhibit sufficient performance as a thermal recording paper. For example, 2-aminomethyl-6-dinithylaminofluorane, which is shown in Publication No. 1, is used in the production of thermal recording paper. There is a defect in which some colors develop and the background color density of the recording paper becomes high. Mainly low, but one color development starting concentration is too high,
The rise of color development was also insufficient, and 2-anilinoni 3
-Methyl-6-N-methyl-N-cyclohexylaminofluorane has insufficient rise of one color.

〔the purpose〕

Unlike the conventional fluoran compounds mentioned above, the present invention uses a special fluoran compound as a coloring component.

By using 1. The purpose of the present invention is to provide a leuco-based heat-sensitive recording material that provides heat-sensitive recording with high color density and high sensitivity.

〔composition〕

According to the invention, the general formula.

A leuco-based heat-sensitive recording material is provided, which contains a fluoran compound represented by the following as a coloring component.

In the front-bifurcated formula, R is an alkyl group having 8 or less carbon atoms, and winter is an allyl group (CH2=CH-CH2-), and R2 is a hydrogen atom, a halogen atom (chlorine, bromine, iodine, etc.). ) or a lower alkyl group, and the number of carbon atoms in the lower alkyl group is 1.
R3 is usually 4 or less, especially methyl, and R3 is a lower alkyl group, and the number of carbon atoms is usually 1.4 or less.

The fluorine compound represented by the general formula (1) of the present invention is a colorless or slightly colored solid in the atmosphere, and when it comes into contact with a conventional color developer for leuco dyes, Then, a blackish pigment is immediately formed, and this colored pigment has excellent storage stability and is therefore extremely effective as a coloring component.

The fluoran compound represented by the above general formula (1) of the present invention is produced by the first method (A) or (B).

(1) Method (A) General formula (wherein R is hydrogen, an atom or a lower alkyl group, R21
, and 1R3 have the same meanings and meanings as defined in the general formula (I) above, and a diphenyl aminated metal compound represented by , - general formula, , p (in the formula, 1 is The benzophenone compound represented by (same meaning as defined in the previous two general formulas [l]) is mixed with a benzophenone compound represented by the following formula in the presence of a condensing agent such as concentrated sulfuric acid at a temperature of 0 to 100°C for several hours to several tens of hours. After the reaction, the reaction mixture was placed in ice water and the precipitate was collected by filtration. After stirring at 100°C for several hours, add toluene and stirring for 1 to 2 hours. By recrystallizing with an organic inert solvent, high purity dichloromethane d(1
) is obtained.

(2) Method (B) A fluoran having a free radical at the 2-position and 1-side group represented by the general formula <wherein R1 and R2 have the same meanings as defined in the general formula (1) above) By reacting the chemical compound and the achotyl-substituted bromo or chloro6ene in a volatile organic inert solvent with potassium carbonate, copper powder, and iodine as catalyst, -m formula (■) is obtained. The represented fluoran compound is produced. From the viewpoint of production, the above method (A) is more preferable.

In the present invention, the condensing agent used in the above (A)O method includes concentrated sulfuric acid, fuming sulfuric acid, acetic anhydride, phosphoric acid, polyphosphoric acid, etc., but preferably 85% or more concentrated sulfuric acid. This is how to use .

The present invention is a leuco-based heat-sensitive recording material containing at least one fluoran compound represented by the above general formula (CI) as a heat-sensitive coloring component. The nine leuco type heat-sensitive recording material can be produced according to a conventionally known method. That is, the fluoran compound according to the present invention and a color developer (for example, a phenolic compound, an organic acid or its salt, an ester or amide, a solid acid, or another electron-accepting substance) are mixed on paper or plastic film using a binder. All you have to do is apply it in a single layer or in multiple layers onto a substrate such as cloth and dry it to form a heat-sensitive coloring layer. In order to improve the whitening effect and writability, this thermosensitive coloring layer contains (aco3, TiO2
, ZnO, talc, clay, kaolyl, etc., and any other auxiliary additives commonly used in this field may be added. The thermosensitive recording materials have a variety of structures, and utilize the color-forming reaction between leuco dyes and primary colorants. The leuco-based heat-sensitive recording material of the present invention includes a heat-sensitive recording material having a structure in which a leuco dye and a color developer are supported on a support as the same coating layer or separate coating layers, and a leuco dye is supported as a transfer layer. It can be used as a thermal transfer type heat-sensitive recording material consisting of a transfer sheet supported on a body and a receptor sheet supported on a support using a color developer as a receptor layer. In the case of thermal transfer type thermal recording materials,
Place the receptor sheet on a transfer sheet, place the receptor sheet in contact with the transfer layer of the transfer sheet, and then print from the front or back side of the polymerized sheet to print on the receptor layer surface of the receptor sheet. ].

A desired colored image can be formed.

The leuco-based heat-sensitive recording material of the present invention is used in various recording fields, particularly as a heat-sensitive recording material for high-speed recording that requires high image stability.

[Results] The fluoranated metal compound represented by the general formula (I) according to the present invention has a colorless structure that is stable in the atmosphere.
．． -color, solid, a7. C1 customary. When it comes into contact with a color developer, a black pigment is immediately formed, and this colored pigment has excellent storage stability, and the leuco-based heat-sensitive recording material containing the fluoran compound has almost no background coloration. It has a high color density, a low starting temperature of one color, and an excellent color development start-up. In addition to heat-sensitive recording materials, Honmei's fluoran derivatives are also used as color-forming dyes in pressure-sensitive recording paper and current-carrying recording paper.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 (Synthesis of 2-4-acetylanilino-6-N-ethyl-N-allylaminofluorane 395% sulfuric acid 1
00■ 2-(4-N-ethyl-N-allylamino-2-hydroxybenzoyl)benzoic acid 2 in Tomoe
2.7. and 16.9 g of 4-methoxy-41-acetyldiphenylamine were added and heated at a temperature of 20 to 30°C for 500 g.
After 0 hours of reaction, pour the reaction mixture into 500ml of ice water.
The precipitate was collected by filtration.

Add 5% aqueous sodium hydroxide solution to the precipitated crystals.

Add 500 ml of toluene, stir at 60-70°C for 1 hour, and add 1. ．． 000-Ω was added and reacted for 2 hours.Then, the toluene layer was separated, the liquid fraction was separated, the toluene layer was dried, and the toluene was removed. The residue was recrystallized from a mixed solvent of ligroin and toluene to give a pale yellow powder with a melting point of 179-182°C. 2-4-
21.2 g of acetylar-rif-6-N-ethyl-N-allylaminofluorane was obtained.

This 1. The elemental analysis values of the fluoran compound are shown in Table 1, and they matched within the error range.

4 Table-1 N% 0% N%, calculation, 婢 5. ．． 47 76.71 5.4 1 Example 2 (2-4-acetylanilino-6-N,N-actual value 5.59 76.63 5.37 error + 0.12 Synthesis of sialylaminofluorane) 95 % sulfur - 100m 2 in 11 (4-N, N-,
Diallylamino-2-hydroxybenzoyl]benzoic acid 23.6. and 4-methoxy-4-acetyl diphenylamine 16.9. By adding and reacting and treating in the same manner as in Example 1, a pale yellow powder with a melting point of 20
2-4-acetylanilino-6 exhibiting a temperature of 9 to 210.5°C
-N,N-diallylaminofluorane 23.4. was gotten.

The elemental analysis values of this fluoran compound are shown in Table 2, and they matched within the error range.

Table-2 H% 0% N% Calculated value 5.3577.24 5.30 Actual value 5.42 Error +0.07 +0.06+0.12Next, each fluoran compound obtained as described above was prepared using silica gel. The coloring hue on the thin layer and the coloring hue of bisphenol A are summarized in Table 3. Table 3 shows R2#R3.

Example 3 [Manufacture of leuco-based heat-sensitive recording material] Part A 2-4-acetylanilino-6-N-ethyl-N-allylaminofluorane 1 part Hydroxyethylcellulose 10% aqueous solution 1 Water 3 B [2. 2-bis(p-hydroxyphenyl)propane 1,
Part hydroxyethyl cellulose 10% aqueous solution 1 Water 23 After dispersing each of the above liquids in separate magnetic lumil for 2 hours, liquid 4 and liquid B were mixed at a ratio of 1:3 (weight ratio),
, a 25% aqueous solution of calcium carbonate and sium was added to the dry weight.
were added and mixed so that 511 colors and 1 component were obtained to prepare a thermosensitive coloring layer forming liquid.

Next, this thermosensitive coloring layer forming liquid was applied to one side of high-quality paper with a basis weight of 4 gg/rd using a wire bar, so that the dry adhesion amount was approximately 4r:/d14, and dried. N
o, 1) was prepared, and for comparison, 2 in liquid A.
No. 1 except that 2-anilino-3-methyl-6-pyrrolidinofluorane was used instead of -4-acetylanilino-6-N-ethyl-N-allylaminofluorane.
Comparative thermal recording paper (No.
2) was created.

The following tests were conducted using these thermosensitive recording papers.

That is, thermal recording paper No. 1 and comparison No. 2 were heated to 90°C.
The color density when a pressure of 2 kg was applied for 1 second at a temperature range of -150°C was measured using a black filter of Macbeth reflection densitometer RD-514. The measurement results are shown in Table 4. Thermal recording paper No. 1 (product of the present invention) is overall superior to thermal recording paper No. 2 (comparative product), especially in ground color density. It was observed that the color density, color development, and rise of the color were low, and that the color density, color development, and rise were significantly superior.

Table-4

Claims (1)

[Claims] (1) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R_1 is an alkyl group or allyl group having 8 or less carbon atoms, R_2 is a hydrogen atom, halogen atom or lower alkyl group, and R_3 is a lower alkyl group. A leuco-based heat-sensitive recording material characterized by using a fluoran compound represented by the following as a coloring component.