JPS62135388A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having excellent developed color density, color forming sensitivity and oil resistance and free of ground fogging, by using a specified gallic acid ester as an electron-acceptive compound and a specified benzoic acid ester as an eutectic forming agent, in a thermal recording layer. CONSTITUTION:A compound of any of general formulas (I)-(III), wherein each of R1, R3 and R4 is a 1-22C alkyl, a 7-12C aralkyl or a 6-10C aryl, and R2 is a lower alkyl, is used as an electron-acceptive compound, and a compound of general formula (IV), wherein each of R5 and R7 is a lower alkyl, R6 is hydrogen or a lower alkyl, and R8 is a 1-22C lower alkyl, a 7-12C aralkyl or a 6-10C aryl, is used as a co-flux, in a thermal color forming layer. A recording material provided with the thermal color forming layer is utilized as a thermal recording material in various recording fields, particularly, for high-speed recording where a high image stability is required.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a heat-sensitive recording material.

More specifically, the present invention relates to a heat-sensitive recording material with improved color development.

[Prior art]

Thermosensitive recording materials generally contain an electron-donating colorless dye (
This device has a heat-sensitive recording layer whose main components are an electron-accepting compound (hereinafter referred to as a color-forming dye) and an electron-accepting compound (hereinafter referred to as a color developer). and a color developer react instantaneously to obtain a recorded image.
It is disclosed in Publication No. 4039 and the like. Such a heat-sensitive recording material allows recording to be obtained using a relatively simple device and is easy to maintain.

It has the advantage of not producing any noise, and is used in a wide range of fields, including measurement recorders, facsimile machines, printers, computer terminals, labels, and automatic ticket vending machines.

The basic performance required for heat-sensitive recording materials is as follows.

Having sufficient color image density and sensitivity, and eliminating background fog (
There is no color development phenomenon due to aging in uncolored areas), and there is no deterioration of colored images over time. However, currently nothing has been obtained that completely satisfies these requirements. Particularly in recent years, the speed of print recording has been increasing, and as the speed of recording apparatuses themselves has increased, there has been a desire to develop recording sheets that can cope with the speed increase, that is, to increase the density of images, and therefore, intensive research is being carried out.

As a method, the melting point of the electron-accepting compound itself is set to 60
The temperature may be increased from 100℃ to 100℃. However, it is difficult to control the melting point of phenolic compounds, which are electron-accepting compounds that are currently widely used, and the phenolic compounds themselves are expensive and impractical.

Another method is to use an organic acid and a phenolic compound together as an electron-accepting substance, as described in Japanese Patent Publications No. 49-17748 and No. 51-39567.

Alternatively, it is described that a polyvalent metal salt of a compound having an alcoholic hydroxyl group is used. Also, special public service 51-2
No. 9945 describes the use of a copolymer of hydroxyethyl cellulose and maleic anhydride.

Also, Japanese Patent Publication No. 51-27599 and Japanese Patent Publication No. 48-19
No. 231 describes the addition of waxes.

Furthermore, JP-A-49-34842, JP-A-49-115
No. 554, JP-A-50-149353, JP-A-52-
No. 106746.

JP-A-53-5636, JP-A-53-11036,
JP-A-5318751 and JP-A-56-7299
In No. 6, nitrogen-containing organic compounds such as thioacetanilide, phthalonitrile, acetamide, di-β-naphthyl-P-phenylenediamine, fatty acid amide, acetoacetanilide, diphenylamine, penzamide, carbazole, etc. or 2,3-di- m-tolylbutane, 4.
Thermofusible substances such as 4'-dimethylbiphenyl, or dimethyl isophthalate, diphenyl phthalate,
The addition of carboxylic acid esters such as dimethyl terephthalate and the like as sensitizers has been described. Furthermore, British Patent Publication No. 2.074,335A describes the addition of hindered phenols.

However, heat-sensitive recording materials produced using these methods are insufficient in color density and color sensitivity.

Furthermore, along with the widespread use of heat-sensitive recording materials, the image stability when exposed to water (water resistance), the fact that it does not fog the skin when layered with diazo copy paper, and the ability to prevent oils contained in hair products and sweat from the skin, etc. Various properties such as image stability (oil resistance) when deposited have become required, and a heat-sensitive recording material that satisfactorily satisfies these requirements has come to be desired.

These improvements have also been widely investigated from the viewpoint of color developers, and JP-A No. 54-155059 and JP-A No. 55-27253 disclose alkylidene bisphenols and JP-A No. 57-156.
No. 293 describes dihydroxybenzoic acid ester, JP-A-5
Monohydroxybenzoic acid esters are disclosed in No. 6-144193 and JP-A-57-129787. However, now.

A thermosensitive recording material that completely satisfies various properties desired has not yet been obtained.

[Objective] An object of the present invention is to provide a heat-sensitive recording material that has excellent color density and color sensitivity, is free from image deterioration due to water or oil, and is free from background fog.

〔composition〕

According to the present invention, in a heat-sensitive recording material containing a normally colorless or light-colored electron-donating dye and an electron-accepting compound that reacts with the electron-donating dye when heated and causes the electron-donating dye to develop a color, the electron-accepting compound may include the following general At least one of the compounds represented by formulas (1) to (III) is used, and at least one of the compounds represented by the following general formula (IV) is contained as a eutectic agent in the heat-sensitive coloring layer. A heat-sensitive recording material is provided.

(In the formula, R1, R3 and R4 are an alkyl group having 1 to 22 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or an aralkyl group having 6 to 12 carbon atoms.
10 represents an aryl group, and R2 represents a lower alkyl group.

) (wherein, R5 and R7 are lower alkyl groups, R6 is
R8 is a hydrogen atom or a lower alkyl group.

It represents a lower alkyl group having 1 to 22 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

) The heat-sensitive recording material of the present invention has the above general formulas (r) to (III
) and a eutectic agent represented by the above general formula (IV), and 9! It has sufficient color density and color development sensitivity, has little decrease in color image density over time, does not cause background fogging, and is extremely practical as it does not cause image deterioration due to water or oil.

Next, specific examples of the color developer according to the present invention will be shown, but the present invention is not limited thereto.

[Specific examples of compounds represented by general formula (1)] (1) Gallic acid methyl ester (2) Gallic acid ethyl ester (3) Gallic acid -〇-propyl ester (4) Gallic acid -〇-butyl ester ( 5) Gallic acid -〇-octyl ester (6) Gallic acid -n-dodecyl ester (7) Gallic acid stearyl ester (8) Gallic acid -〇-dodecyl ester (9) Gallic acid benzyl ester (10) Gallic acid-2 '-Methylbenzyl ester (1
1) Gallic acid-4'-methylbenzyl ester (12)
Gallic acid-4'-ethylbenzyl ester (13) Gallic acid-2'-chlorobenzyl ester (14) Gallic acid-4'-chlorobenzyl ester (15) Gallic acid-α
-Naphthyl methyl ester (16) Gallic acid-2'-methyl-α-naphthyl methyl ester [Specific example of the compound represented by general formula (■)] (1)
3.4-dihydroxy-5-methoxybenzoic acid methyl ester (2) 3.4-dihydroxy-5-methoxybenzoic acid ethyl ester (3) 3.4-dihydroxy-5-methoxybenzoic acid-n-propyl ester (4 ) 3.4-dihydroxy-5-methoxybenzoic acid-n-butyl ester (5) 3.4-dihydroxy-5-methoxybenzoic acid benzyl ester (6) 3.4-dihydroxy-5-methoxybenzoic acid-2' -Methylbenzyl ester (7) 3.4-dihydroxy-5-methoxybenzoic acid-4'-methylbenzyl ester (8) 3.4-dihydroxy-5-methoxybenzoic acid-2'-chlorobenzyl ester (9) 3 .4-dihydroxy-5-methoxybenzoic acid-4'-chlorobenzyl ester (10) 3,4-dihydroxy-5-methoxybenzoic acid ethyl ester (11) 3.4-dihydroxy-5-methoxybenzoic acid-4' -Methylphenyl ester (12) 3.4-dihydroxy-5-methoxybenzoic acid-4'chlorophenyl ester (13) 3.4-dihydroxy-5-ethoxybenzoic acid methyl ester (14) 3.4-dihydroxy- 5-Ethoxybenzoic acid ethyl ester (15) 3.4-dihydroxy-5-ethoxybenzoic acid benzyl ester (16) 3.4-dihydroxy-5-ethoxybenzoic acid 2'-methylbenzyl ester (17) 3.4 -Dihydroxy-5-ethoxybenzoic acid-4'-chlorobenzyl ester (18) 3.4-dihydroxy-5-ethoxybenzoic acid phenyl ester (19) 3.4-dihydroxy-5-ethoxybenzoic acid-4'-methyl Phenyl ester [Specific examples of compounds represented by general formula (m)] (1)
3.4-dihydroxybenzoic acid methyl ester (2) 3.4-dihydroxybenzoic acid ethyl ester (3) 3.4-dihydroxybenzoic acid-n-propyl ester (4) 3.4-dihydroxybenzoic acid benzyl ester (5 ) 3.4-dihydroxybenzoic acid-2'-methylbenzyl ester (6) 3.4-dihydroxybenzoic acid-4'-ethylbenzyl ester (7) 3.4-dihydroxybenzoic acid-2'-chlorobenzyl ester ( 8) 3.4-dihydroxybenzoic acid-4'-chlorobenzyl ester (9) 3.4-dihydroxybenzoic acid-α-naphthylmethyl ester (10) 3.4-dihydroxybenzoic acid-2’-methyl-α- Naphthyl methyl ester (11) 3,4-dihydroxybenzoic acid phenyl ester (12) 3,4-dihydroxybenzoic acid-4'-methylphenyl ester Color developer, e.g. bisphenol A,
It is also possible to use it in combination with 4-hydroxybenzoic acid benzyl ester and the like. In the present invention, these color developers are used in an amount of 1 to 6 parts by weight per 1 part by weight of the color-forming dye.

In the present invention, a eutectic agent represented by the general formula (IV) is used together with the color developer, but it is necessary to select a eutectic agent that does not substantially cause the color-forming dye described below to develop color. .

Next, specific examples of the eutectic agent according to the present invention will be shown, but the present invention is not limited thereto.

(1) 4-hydroxy-3,5-dimethoxybenzoic acid methyl ester (2) 4-hydroxy-3,5-dimethoxybenzoic acid ethyl ester (3) 4-hydroxy-3,5-dimethoxybenzoic acid n
-Propyl ester (4) 4-hydroxy-3,5-jethoxybenzoic acid methyl ester (5) 4-hydroxy-3,5-jethoxybenzoic acid ethyl ester (6) Benzyl 4-hydroxy-3,5-dimethoxybenzoate Ester (7) 4-hydroxy-3,5-dimethoxybenzoic acid-ρ-methylbenzyl ester (8) 4-hydroxy-3,5-dimethoxybenzoic acid-
〇-Chlorbenzyl ester (9) 4-hydroxy-3,5-jethoxybenzoic acid-
ρ-Chlorbenzyl ester (10) 4-hydroxy-3,5-dimethoxybenzoic acid-β-phenethyl ester (11) 3,4.5-trimethoxybenzoic acid methyl ester (12) 3,4.5-trimethoxybenzoic acid Ethyl ester (13) 3,4.5-trimethoxyamne, Q, fragrant n
-Propyl ester (14) 3,4.5-trimethoxybenzoic acid benzyl ester (15) 3,4.5- )-rimethoxybenzoic acid-p
-Methylbenzyl ester (16) 3. /1.5-1 herimethoxybenzoic acid-P
-Chlorbenzyl ester (17) 3,4.5- trimethoxybenzoic acid-0-
Chlorbenzyl ester (18) 3,4.5-trimethoxybenzoic acid-β-phenethyl ester (19) 3,4.5-)-liethoxybenzoic acid methyl ester (20) 3,4.5-)-liethoxybenzoic acid Ethyl ester (21) 3,4.5-triethoxybenzoic acid benzyl ester (22) 3,4.5-triethoxybenzoic acid-P-chlorobenzyl ester and the like. In the present invention, the above eutectic agents may be used alone or in combination of two or more. These eutectic agents are preferably used in an amount of 0.5 to 6 parts by weight per 1 part by weight of the color-forming dye.

Further, in the present invention, examples of the metal stearate used as necessary include zinc stearate, aluminum stearate, lead stearate, calcium stearate, barium stearate, magnesium stearate, and the like. These may be used alone or in combination of two or more. Suitably, the amount of these metal stearates is 6 parts by weight or less per 1 part by weight of the coloring dye.

The leuco dyes used in the present invention can be applied singly or in combination of two or more types, but such leuco dyes include:
Those applied to this type of heat-sensitive material can be arbitrarily applied. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferably used. . Specific examples of such leuco dyes include those shown below.

3.3-bis(p-dimethylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3.3-bis(p- dimethylaminophenyl)-6-dibutylaminophenyl.

3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5, 7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane.

3-(N-ρ-tri-N-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-trifluoran) methylphenyl)amino)-6-dinithylaminofluorane.

2-(3,6-bis(diethylamino)-9-(o-
chloranilino)xantylbenzoic acid lactam), 3-
Diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7-(o-chloroanilino)fluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, 3-N-methyl -N-amylamino-6-methyl-7-
Anilinofluorane.

3-N-Methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane.

3-diethylamino-6-methyl-7-anilinofluorane, 3-(N,N-diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 3-(2'- Hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide.

3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)-3- (2'-methoxy-5'-methylphenyl)phthalide, 3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-( N-benzyl-trifluoromethylanilino)fluoran, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluoran, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-p-toluidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-( α-)Dylethylamino)fluorane, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-5-(N-methyltoluidino)-7-(p-n
-butylanilino)fluorane, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane, 3.6-simethoxyfluorane, 3-(p-dimethylaminophenyl)-3-phenylphthalide, 3-di(1-ethyl-2-methylyldol)-3 -yl-phthalide, 3-diethylamino-6-phenyl-7-azafluorane.

3.3-Bis(P-diethylaminophenyl)-6-dimethylaminophthalide.

2-bis(p-dimethylaminophenyl)methyl-5-
Dimethylamino-benzoic acid, 3-(P-dimethylaminophenyl)-3-(p-dibenzylaminophenyl) phthalide.

3-(N-ethyl-N-n-amyl)amino-6-methyl-7-anilite fluorane and the like.

In the present invention, in order to bind and support the leuco dye, color developer, eutectic agent and/or stearate metal salt on the support, various conventional binders such as those described below can be used. .

Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate,
Polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer alkali salt, inbutylene/maleic anhydride copolymer In addition to water-soluble polymers such as polymer alkali salts, polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride/vinyl acetate Latex such as copolymers, polybutyl methacrylate, ethylene/vinyl acetate copolymers, styrene/butadiene/acrylic copolymers, etc.

In the present invention, in addition to the above-mentioned components, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, lubricants, sensitization improvers, antioxidants, and ultraviolet rays, may be added. An absorbent or the like can be used in combination. In this case, examples of the filler include kaolin, calcined kaolin, talc, waxite, diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate, titanium oxide, barium carbonate, urea-formalin resin, cellulose, and the like.

The heat-sensitive recording material of the present invention can be produced, for example, by applying a coating liquid for forming a heat-sensitive layer obtained by pulverizing and dispersing the above-mentioned components onto a suitable support such as paper, synthetic paper, or plastic film, and drying the coating liquid. It is produced and used in various recording fields, especially as a heat-sensitive recording material for high-speed recording that requires high image stability.

〔effect〕

The heat-sensitive recording material of the present invention contains an electron-accepting compound (color developer)
At least one compound of the general formulas (I) to (III) is used as a eutectic agent, and at least one compound of the general formula (I) is used as a eutectic agent.
Since the compound V) is used, it has excellent coloring density and coloring sensitivity, has little image deterioration due to water, oil, etc., and is of practical use without background fog.

〔Example〕

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

Note that parts are based on weight.

Example 1 Mixtures with the following compositions were placed in separate ball mills:
Pulverized and dispersed to a particle size of 1 to 5 μm to form liquid A, liquid D, liquid C, and liquid D.
A liquid and a liquid E were prepared.

[A liquid]

2-anilino-3-methyl-6-(N-methyl-N-cyclohexyl)aminofluorane 10 parts Hydroxyethylcellulose 10% aqueous solution 10 parts Water
30 parts [Liquid B] 3.4-dihydroxybenzoic acid-P-chlorobenzyl ester 10 parts 10% aqueous solution of hydroxyethylcellulose 10 parts water
3
0 parts [Liquid C] 4-hydroxy-3,5-dimethoxybenzoic acid methyl ester 10 parts 10% aqueous solution of hydroxycellulose 10 parts water
30 parts [Liquid D] Aluminum stearate 20 parts Methyl cellulose 2 parts Polycarboxylic acid type surfactant 2 parts Water
76 parts [Liquid E] Calcium carbonate 25 parts Methylcellulose 2 parts Water
A heat-sensitive color forming layer coating solution having the following composition was prepared using 73 parts or more of the A-E solution obtained as described above.

[Coating liquid]

A liquid 13 parts B
Liquid 36 parts C liquid 2
6 parts D liquid 16 parts E
Liquid 36 parts 20% alkaline aqueous solution of inbutylene-maleic anhydride copolymer
8 parts Next, apply this coating solution to commercially available high-quality paper with a standard basis weight of 48 g/m in a dry coating amount of 7 to 9 g/m.
It was applied so that it became rd. After drying, the surface of the heat-sensitive coloring layer was smoothed using a super calender to prepare a heat-sensitive recording material of Example 1 of the present invention.6 Examples 2 to 10 The color developer of Example 1 (3,4-dihydroxybenzoic acid-4
'-chlorobenzyl ester), eutectic agent (4-hydroxy-3,5-dimethoxybenzoic acid methyl ester),
and metal stearate (aluminum stearate)
Heat-sensitive recording materials of Examples 2 to 10 of the present invention were prepared in the same manner as in Example 1, except that the compounds shown in Table 1 were used instead of .

Comparative Examples 1-2 Color developer of Example 1 (3,4-dihydroxybenzoic acid-4
The heat-sensitive recording materials of Comparative Examples 1 and 2 were prepared in the same manner as in Example 1, except that the compounds shown in Table 1 were used instead of chlorobenzyl ester) and the eutectic agent and metal stearate were omitted. Created.

The heat-sensitive recording material obtained as described above was printed using a thermal gradient tester (manufactured by Toyo Seiki) at 1 pressure of 2 kg and 110°C for 1 second, and the color density was measured using a Macbeth densitometer RD-514 model (filter V-106). ) was measured. Next, regarding the heat-sensitive recording material printed at a temperature of 150°C using the same method as above,
An oil resistance test and a greasy mark resistance test were conducted.

The results are shown in Table-1. Note that each test was conducted using the following test method.

Oil resistance: Apply a very thin layer of cottonseed oil to the colored image area, leave it at room temperature for one day, and then visually observe and evaluate the colored image.

Resistance to grease marks: A grease mark is attached to a colored image, and the colored image is left for one week at room temperature, and then the colored image is visually observed and evaluated.

Claims (2)

[Claims] (1) In a heat-sensitive recording material containing a normally colorless or light-colored electron-donating dye and an electron-accepting compound that reacts with the electron-donating dye when heated to cause the electron-donating dye to develop color, the electron-accepting compound may be of the following general formula ( It is characterized by using at least one of the compounds represented by I) to (III) and containing at least one of the compounds represented by the following general formula (IV) as a eutectic agent in the heat-sensitive coloring layer. A heat-sensitive recording material. ▲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 formula, R_1, R_3, and R_4 are Carbon number 1-22
R_2 represents an alkyl group having 7 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and R_2 represents a lower alkyl group. ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(IV) (In the formula, R_5 and R_7 are lower alkyl groups, R_
6 represents a hydrogen atom or a lower alkyl group, and R_8 represents a lower alkyl group having 1 to 22 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms. ) (2) The heat-sensitive recording material according to claim 1, further containing a metal stearate.