JPH02122979A - heat sensitive recording material - Google Patents

Abstract

PURPOSE:To contrive higher brightness and higher high-speed recordability by incorporating a specified aromatic amide in a thermal color forming layer of a thermal recording material. CONSTITUTION:At least one aromatic amide compound of any of formulas I to III is incorporated in a thermal color forming layer of a thermal recording material which utilizes a color reaction between a colorless or light-colored basic leuco dye and a color reaction agent. When the compound, as a specified heat-fusible material, is incorporated in the color forming layer, the favorable compatibility of the compound itself with the dye and the color reaction agent enhances color forming sensitivity. In addition, because the compound is difficultly soluble in water, the compound does not lower brightness. As the heat-fusible substance, either one of the compounds of formulas I to III may be used together with the leuco dye and the color reaction agent, or two or more of the compounds may be used jointly. Other sensitizers may be used jointly, in such a range as not to hinder the desired effect. The amount of at least one compound to be used is 10-1000wt.% based on the color developer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a heat-sensitive recording medium, and particularly to a heat-sensitive recording medium that has high whiteness and excellent suitability for high-speed recording.

[Conventional technology]

Heat-sensitive recording materials that utilize a heated coloring reaction between normally colorless or light-colored leuco dyes and phenols or organic acids have been published in Japanese Patent Publications No. 43-4160, No. 45-14039, No. 27736-1973, etc. , has been widely put into practical use. In recent years, heat-sensitive recording materials such as σ) have been widely used as various information recording materials due to their advantages such as the ability to form colored images simply by heating and the ability to make recording devices relatively compact. ing.

Especially a heat-sensitive recording medium like this? Thermal facsimile machines, thermal printers, etc. used have been improved in terms of their positioning, and it has become possible to perform high-speed printing and high-speed image formation, which was previously difficult. As the speed of such equipment and hardware increases, the heat-sensitive recording media used are required to have significantly improved recording sensitivity than before. Many proposals have been made to meet this demand, most of which involve the combination of a basic dye and a color former, with the addition of a thermofusible substance.

Such a thermofusible substance? When the heat-sensitive recording medium containing
First, the thermofusible substance melts, and it becomes a dye, coloring agent, etc. By dissolving the two, they mix at the molecular level and a color reaction is induced. Therefore, these thermofusible substances must have an appropriate melting point (preferably 60 DEG -140 DEG C.) and be highly compatible with dyes and coloring agents. Also, what is the whiteness of the thermal recording material? In order to prevent the degradation, it is desirable that these thermofusible substances have extremely low solubility in water, and also have properties such as low sublimation. It is desirable to have one. In the latter case, the heating coloring part of the heat-sensitive recording medium becomes powdery over time. It is thought that this phenomenon is closely related to the phenomenon of so-called whitening, which causes a wispy appearance, and is an extremely difficult property for thermal recording materials in practical terms. Although many of these thermofusible materials have been proposed in the past, there are only a few Q] that satisfy all of the above conditions, and new materials have been sought.

The present invention provides a new thermofusible substance to be used together with the aforementioned leuco dye and coloring agent, and applies it to a heat-sensitive recording medium to significantly improve the recording sensitivity of the recording medium and to improve recording performance. Is it important not to reduce the quality of the products involved? purpose.

〔problem? Means to solve]

The purpose of the inventors? As a result of repeated research to achieve this goal, the following general formula [I] was found as a thermofusible substance.

When an aromatic amide compound represented by [■] or [III] is used, (R in the above formula represents an aryl group or an aralkyl group) stearic acid amide, which has been proposed as a thermofusible substance , reduced whiteness compared to higher fatty acid amides such as palmitic acid amide? The present inventors have discovered that extremely high recording sensitivity can be obtained without experiencing phenomena such as whitening, which deteriorates the quality of colored images over time, and have completed the present invention.

The present invention provides a heat-sensitive recording material having a heat-sensitive color-forming layer in which a color reaction between a leuco dye and a coloring agent is used as a first coloring reaction between a colorless or monochromatic salt (Ii); At least one of the aromatic amide compounds represented by the above general formula CI], [II] or CIII? Did you make it look like this? This is a characteristic heat-sensitive recording medium.

What is the coloring sensitivity of a thermosensitive recording medium that contains a specific thermofusible substance (hereinafter referred to as a sensitizer) as mentioned above? Although the reason for the improvement is not clear, one of the reasons is presumed to be that these compounds themselves have good compatibility with dyes and coloring agents. Furthermore, the reason why it does not reduce whiteness and discoloration is thought to be due to its low sublimation property, although it is poorly soluble in water, and there are extremely few phenomena that deteriorate recorded image quality such as whitening. It's not something that sticks to.

Sensitizers constituting the present invention σ) Specific examples include the following: Can you name it?

These aromatic amide compounds can be easily synthesized in high yield from the corresponding aromatic acid-ride, aromatic amine or substituted amine group-containing acid-ride, and phenol or its derivatives, as shown in the reaction formula below. can do.

(The substituent R is an aryl group, R2 is a hydrogen atom or an aryl group, and R3 is an alkyl group.

Is X a halogen atom? show. ] This invention? Any one of the constituting thermofusible substances may be used together with a compound (Q), a leuco dye, or a coloring agent, or two or more thereof may be used in combination. Further, it may be used in combination with other sensitizers within a range that does not inhibit the desired effects of the present invention. The amount of the compound of the present invention to be used is 10 to 1000 tons, preferably 50 to 300% by weight, based on the color developer.

The heat-sensitive color forming layer using the compound of the present invention mainly consists of leuco dyes,
It consists of a coloring agent made of phenols or organic acids, and the compound of the present invention. Further, the coloring layer preferably contains an inorganic pigment, and may further contain waxes if necessary. Other of these ingredients? It should contain a binder as an essential ingredient to fix it to the support.

As the leuco dye, conventionally known dyes may be used, such as the following.

Crystal violet lactone, 3-(N-ethyl-N
-(bentylamino)-6-methyl 7-anilinofluorane, 3-diethylamino 6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-(
011)-dimethylanilino)fluorane, 3-(N-
Ethyl-p-)luidino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-
Anilinofluorane, 3-(N-cyclohexyl-N-
methylamino)-6-methyl-tuanilinofluorane, 3-diethylamine-7-(0-10 roanilino)fluoran, 3-diethylamino-7-(m-trifluoromethylanilino)fluorane, 3-diethylamine-
6-Methyl-7-chlorofluoran, 3-diethylamino-6-methylfluoran, 3-cyclohexylamino-6-chlorofluoran.

The same is true for coloring agents made of phenols or organic acids.
Conventionally known ones may be used, and the following are listed as examples.

Bisphenol A, P-hydroxy heptabenzoic acid Hensyl,
Di(4-hydroxyphenyl) vinegar & n-butyl, bisphenol S, 4-hydroxy-4'-inglobyloxydiphenyl sulfone, 11-cy(4-hi)"roxyphenyl]cincrohexa7.1, 7-cy(hydroxy) phenylthio)-3゜5-dioxahebutane.

Here, as a sensitizer that can be used in combination with the compound of the present invention, a thermofusible organic compound with a melting point of 50-150°C is used. This is an example.

l'-V-J Terhydroxynaphthoic acid phenyl ester, p-benzylbiphenyl, benzyl naphthyl ether, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, diphenyl carbonate, ditolyl carbonate, m-terphenyl, ethylene glycol di- m-tolyl ether.

Organic or inorganic pigments used in one coloring layer include aluminum carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, and clay.
In addition to inorganic fine powders such as talc, surface-treated carbonate, and silica, examples include organic fine powders such as urea-formalin 81 Di, styrene/tuacrylic acid copolymer, and polystyrene resin. .

Furthermore, is the coloring layer of the present invention made of various types of wanks? Obtain what is included as necessary. They may include known ones such as paraffin, amide wax, bisimide wax, and metal salts of higher fatty acids. Also, regarding the adhesive,
Polyvinyl alcohol of various molecular weights, starch and its derivatives, cellulose derivatives such as methoxycellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acrylic amide/acrylic Acid ester/methacrylic acid ternary copolymer, styrene/manoic anhydride copolymer alkali salt, polyacrylamide, sodium alginate,
In addition to water-soluble polymers such as gelatin and casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymers,
Polyacrylic acid, polyacrylic ester, vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/
Latexes such as acrylic copolymers can be used.

A mixture that develops color when heated by appropriately mixing these materials is coated on paper, coated paper with a surface coating of clay, plastic, etc., synthetic paper made mainly from plastic, or even plastic film. Made with heat-sensitive recording material. The coating amount is 1 to 1 when the coating layer is dry.
l Og/- is preferable, 2 to 7 g/rr? is particularly preferred.

In this way, the heat-sensitive recording material obtained by the present invention has excellent high-speed recording suitability, high whiteness, and has undesirable properties such as whitening in the recorded image area. Not shown.

EXAMPLES The present invention will be specifically explained below with reference to Examples. Unless otherwise specified, numbers represent parts by weight.

[Implementation date]

Synthesis Example 1 54.2gQ] Nphenylamine 'a' Dissolved in 50 ml of dry pyridine to form a solution? Cool with water to -5°C. This temperature? 546g of 2nd grade acetyl chloride while maintaining it slowly? Drip. While returning to room temperature 1
The mixture was stirred overnight and the reaction-completed solution was filtered. It was confirmed to be the target compound [E] by mass spectrometry and nuclear magnetic resonance (NMR) analysis.

Synthesis Example 2 10,0 gσ]p-cresol? Dissolve the solution in dry pyridine and cool to -5°C. This temperature 11
ffYHochinagaG:r l 0. A solution of enylcarmonol chloride 7a1'25m of Og in tetrahydrofuran was slowly added dropwise. Reaction liquid? Continue stirring for 2 days while returning to room temperature. Reaction liquid? A brown solid was obtained by filtration and distilling off the solvent from the filtrate. Recrystallize this from ethanol and get 17.1g of white crystals? Obtained. Target compound CB was determined by mass spectrometry and NMR analysis.
] was confirmed.

Example 1 ■ Preparation of dispersion liquid A 3-(N-(Soventel-N-ethyl 79)]-6-methyl-7-anilitufluorophone polyvinyl alcohol 1
0%M 10 water
70 This composition was ground with a sand grinder to an average particle size of 1 μm.

(■ Dispersion tj, B Preparation 4.4'-Ingropylidenediphenol Compound of the Invention (A) l O Polyvinyl Alcohol 1o1i 10 Water
70 This composition was ground to an average particle size of 111 m using a sand grinder.

■ Preparation of coloring layer 40 parts of the above AgJL, 160 parts of liquid B, 40 parts of calcium carbonate pigment, 20 parts of 30% paraffin dispersion, and 180 parts of 10% polyvinyl alcohol aqueous solution were mixed, stirred, and mixed with the coating liquid. did.

σ) Coating amount after drying of 50 g/- base paper of coating liquid: 7
．． 5g/n? Is it coated and dried on thermal recording paper? Obtained.

Example 2 ■ Preparation of pigmented undercoated paper 85 parts of baked Ray (trade name: Anciresox) were mixed with 320 parts of water.
20 parts of styrene-butadiene copolymer emulsion (solid content 50%) and 50 parts of 10% oxidized starch aqueous solution 1Y were mixed into the resulting dispersion, and 48 g of the coating liquid was obtained.
yr? A pigment-primed paper was obtained by coating the base paper so that the coating weight after drying was 7, Og/-.

■ Formation of coloring layer 50 parts of dispersion A, 200 parts of dispersion B, 2 parts of calcium carbonate
5 parts of a 30% paraffin dispersion, and 180 parts of a 10 tiborivinyl alcohol aqueous solution were mixed and stirred to prepare a coating liquid. The obtained coating liquid was coated with the above pigment undercoated paper and dried so that the coating amount after drying was 5.0 g / m',
Thermal recording paper? Obtained.

Example 3 In BQ preparation, VC (
Thermal recording paper was prepared in the same manner as in Example 2 except that compound (E)Y was used. Obtained.

Comparative Example I A thermosensitive recording paper was obtained in the same manner as in Example 1 except that stearic acid amide was used instead of (A) in the preparation of liquid B.

Comparative Example 2 A thermosensitive recording paper was obtained in the same manner as in Example 2, except that stearic acid amide was used instead of the compound (A) of the present invention in the Bi preparation.

Comparative Example 3 In Bi preparation, instead of compound (A) of the present invention,
-Thermosensitive recording paper prepared in the same manner as in Example 2 except that hydroxy-2-naphthoic acid phenyl ester was used. Obtained.

The six types of heat-sensitive recording papers prepared as described above were treated with a supercalender so that the surface smoothness as determined by an iY Beck smoothness meter was 600 to 1000 seconds. The samples thus obtained were subjected to measurement of recording sensitivity, measurement of color density of uncolored areas on the surface of the recording layer, and comparative test of white r, and the results are shown in Table 1.

Is the recording sensitivity of the Toyo Seiki thermal gradient tester? used, temperature 120
The sample was heated for 100 seconds at ℃ pressure 2.5 K9/cd.The color density at that time was measured using Macbeth RD-914, and the recording sensitivity of the thermal paper was measured. A representative value was used.

The density of the uncolored area (blank area) of the recording paper was measured using the same densitometer and used as a representative value of whiteness.

Does whitening occur when the sample is tested at a temperature of 150°C using the tester mentioned above? After color development, the color development area was left in an environment of 40° C. and 90% for 24 hours, and changes in the surface were sensory evaluated.

In the table, ○ indicates that no change is observed in the colored printed area, and X indicates that the printed surface becomes powdery, so-called whitening. show.

Table 1 [Effects of the Invention] As described above, since the heat-sensitive recording medium of the present invention uses a new thermofusible material, it has excellent high-speed recording suitability.1. It has a high degree of whiteness, does not induce undesirable phenomena such as whitening, and has extremely low quality.

Claims (1)

[Scope of Claims] A thermosensitive recording material having a thermosensitive coloring layer that utilizes a coloring reaction between a colorless or light-colored basic dye and a coloring agent, in which the thermosensitive coloring layer contains the following general formula [I], [II] or [II
I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼[I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼[II] ▲There are mathematical formulas, chemical formulas, tables, etc.▼[III] (In the above formula, R is an aryl group, or an aralkyl group.) A thermosensitive recording material characterized by containing at least one aromatic amide represented by