JPH03218888A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having high sensitivity and excellent running properties by providing a thermal color forming layer containing a compound represented by a specific formula and finely dividing said compound in an aqueous alkyl modified polyvinyl alcohol solution before use. CONSTITUTION:A thermal color forming layer containing at least an electron donating leuco dye, an electron acceptive compound a a compound represented by formula [1] (wherein R1-R4 are a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom) is provided and the compound represented by the formula [1] is finely divided in an aqueous alkyl modified polyvinyl alcohol solution so as to obtain an average particle size of 0.4 -1.0mum before use. As the compound represented by the formula [1], for example, 4'-methoxyphenyl-4- methylbenzyl ether, 4'-methooxyphenyl-4-chlorobenzyl ether, 4'-ethoxyphenyl-4- chlorobenzyl ether or 3'-methyl-4-chlorophenyl-4-methoxybenzyl ether are designated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material in which a coloring layer containing an electron-donating colorless dye and an electron-accepting compound is provided on a support. Concerning recording materials.

(Prior Art) Recording materials using electron-donating colorless dyes and electron-accepting compounds are already well known as pressure-sensitive paper, thermal paper, light-sensitive pressure-sensitive paper, electrically conductive thermal recording paper, thermal transfer paper, and the like. For example, British Patent No. 2140449, U.S. Patent No. 4480052, U.S. Patent No. 4436920, Japanese Patent Publication No. 60-23992, Japanese Unexamined Patent Publication No. 57
-179836, 60-123556, 60-12
I am familiar with 3557 etc. In particular, heat-sensitive recording materials were
For details, see No. 3-4160, Japanese Patent Publication No. 45-14039, etc. In recent years, there has been active research into increasing the speed and lowering energy of thermal recording systems, and the present inventors have conducted various studies on electron-donating colorless dyes and sensitizers, and have developed a compound represented by the general formula [1]. It has been found that sensitivity can be improved by using However, [1
The compound of the formula is usually used after being atomized, but with water-soluble polymers such as polyvinyl alcohol that have been conventionally used as protective colloids, atomization does not proceed and the sensitivity enhancement effect is halved.

(Object of the Invention) An object of the present invention is to provide a heat-sensitive recording material that is highly sensitive and has excellent running properties.

(Accomplishment of the Invention) An object of the present invention is to provide a heat-sensitive recording material having a heat-sensitive coloring layer containing at least an electron-donating colorless dye, an electron-accepting compound, and a compound represented by the following general formula [1]. ) in an alkyl-modified polyvinyl alcohol aqueous solution with an average particle size of 0.4 μm to 1.0 μm.
μml: A heat-sensitive recording material characterized by being used after being atomized.

(In the above formula, IRI ~ R▲ is a hydrogen atom, an alkyl group, 7
Indicates a alkoxy group and a halogen atom. ) Specific examples of the compound represented by general formula (1) are the following compounds: 4'-methoxyphenyl-4-methylpencyl ether, 4'-
Methyl phenyl-4-methoxyhenzyl ether, 4'
-methoxyphenyl-4-chlorobenzyl ether, 4
'-Ethoxyphenyl-4-chloroOhenzyl ether,
4'-chlorophenyl-4-methoxypencyl ether, 3'-methyl-4'-1-phenyl-4-methoxybenzyl ether, etc. These compounds are described, for example, in JP-A-58-57989, JP-A-58- Compounds disclosed in 87094 and the like can also be used in combination. Representative examples include aromatic ethers, esters, and/or aliphatic amides or ureidos.

The binder used in the present invention has a terminal end modified with 7-alkyl, and the 7-alkyl group has 1 to 20 carbon atoms, and even if there is a side chain, it does not change, and even if it is a mixture with other modifications. I do not care.

Further, in order to further improve the strength of the coating film, other binders may be used in combination or additionally added.

Specific examples of these hinderers include methylcellulose, carboxymethylcellulose, starches (including modified starches), gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, polyacrylic 7amide, vinyl acetate. Synthetic polymers such as saponified polyacrylic acid copolymers, styrene-butadiene copolymers, vinyl acetate copolymers, acrylic nitrile-butadiene copolymers, methyl acrylate-butadiene copolymers, and polyvinylidene chloride latex type hider.

Further, a crosslinking agent suitable for the binder may be added depending on the type of the binder, if necessary.

As the pigment used in the heat-sensitive coloring layer of the present invention, all pigments conventionally used in heat-sensitive recording materials can be used, but from the viewpoint of maintaining coating film strength, light calcium carbonate is particularly preferred.

As the metal soap used in the present invention, higher fatty acid metal salts are used, such as zinc stearate, calcium stearate, heptaruconium stearate, and the like.

As the wax, paraffin wax, microcrystalline wax, carnauba wax, methylolstearamide, polyethylene wax, polystyrene wax, fatty acid amide wax, etc. may be used alone or in combination.

Next, a method for producing the heat-sensitive recording material of the present invention will be described.

Electron-donating colorless dye, electron-accepting compound, general formula (1)
The compound is dispersed to a size of 1.0 μm or less using a Pall mill, a sand mill, etc. together with an aqueous solution of 7-alkyl-modified polyvinyl alcohol. The average particle size as used in the present invention refers to the average particle size measured by Microtrac particle size analyzer (LEEDS
(manufactured by UP) to measure the value.

The compound of general formula (1) may be added to either or both of the electron-donating colorless dye and the electron-accepting compound and dispersed simultaneously, or in some cases, a eutectic may be prepared in advance and dispersed.

In addition, pigments can be processed using Pall Mill, Sand Mill, Kedimir, etc., along with surfactants, dispersants, water-soluble polymers, etc.
Dispersed using a homogenizer, etc.

After dispersion, these dispersions are mixed, and if necessary, surfactants, binders, metal soaps, waxes, antioxidants,
A heat-sensitive coating liquid is made by adding ultraviolet absorbers, etc.

The obtained heat-sensitive coating liquid is coated on high-quality paper, high-quality paper with an undercoat layer,
It is coated and dried on synthetic paper, plastic film, etc.
A recording material is obtained by coating and drying preferably on high-quality paper having an undercoat layer.

Furthermore, the obtained recording material can be provided with a protective layer if necessary, and can be applied simultaneously or sequentially with the heat-sensitive coloring layer, but from the viewpoint of increasing sensitivity, a water-soluble Those consisting of polymers, pigments, and metal soaps are preferred.

Specific examples of electron-donating colorless dyes include the following compounds. Examples include triarylmethane compounds, diphenylmethane compounds, xanthene compounds, thi7dine compounds, and spiropyran compounds. Specific examples include those described in JP-A-55-227253 and the like.

To disclose some of these, tri7lylmethane compounds include 3,3-bis<p-dimethylaminophenyl>-6-dimethyl7minophthalide, 3,3-bis-(
p-dimethylaminophenyl) phthalide, 3-(p-dimethylaminophenyl)-3-(1,3-dimethylindol-3-yl)phthalide, 3-(p-dimethyl7minophenyl)-3-(2- Methylindole-3-
yl) phthalide, etc. Diphenylmethane compounds include 4,4'-bis-dimethyl 7-minobenzhydrin benzyl ether, N-halophenylleukoolamine, N-2. 4. 5-trichlorophenyl leukoolamine, etc., and xanthene compounds include O-damine-8-7-nilinolactam, rhodamine-(p-nitrino)lactam, 2-(dibenzyl-7mino)fluorane, and 2-7-nilino-3-methyl. -6-
ethylaminofluorane, 2-7nilino-3-methyl-6-dibutylaminofluorane, 2-7nilino-3-methyl-6-N-ethyl-N-isoamyl-7minofluorane, 2-7nilino-3-methyl-6- N-methyl-N-cyclohexylaminofluorane, 2-7nilino-3-chloro-6-diethylaminofluorane, 2
-7 Nilino 3-methyl-6-ethyl-N-isobutylaminofluorane, 2-7 Nilino 6-sibutylaminofluorane, 2-anilino 3-methyl-6-N-
Methyl-N-tetrahydrofurfurylmethyl7minoflurane, 2-7nilino3-methyl-6-biperidinoaminofluorane, 2-(o-chloro7nylino)-6-diethylaminofluorane, 2-(3 .4- Dichlor 7
Nilino)-6-ethylaminofluorane, 2-7nilino-3-methyl-6-N-ethyl-N-n-hexylaminofluorane, 2-7nilino-3-methyl-6-toethyl-N-γ-ethoxy Bropylaminofluorane, 2-7nilino-3-methyl-6-N-methylto γ
-Ethoxyprobyl cyaminofluorane, 2-7nilino 3-methyl-6-N -ethyl-N-γ-methoxyprobyl 7minofluorane, 2-7nilino 3-methyl-6
- Dipentyl 7-minofluorane, etc., and examples of thi7dine-based compounds include henzoyl-7-methylene blue,
There are ρ-nitrobenzylleucomethylene blue, etc., and spiro-based compounds include 3-methyl-spiro dinaphthopyran, 3-ethyl-spiro dinaphthopyran, and 3-ethyl-spiro dinaphthopyran.
．． 3'-dichloro spiro dinaphthopyran, 3-
Examples include penzyl spiro dinaphthobilane, 3-methylnaphtho(3-methoxybenzo)-spiropyran, and 3-propyl spiro-cybenzobilane.

As the electron-accepting compound, phenolic compounds or salicylic acid derivatives and polyvalent metal salts thereof are preferred. To give some examples of these, phenolic compounds include 2
, 2-bis(4-hydroxyphenyl)propane (
Bisphenol A), 4-t-butylphenol, 4-
phenylphenol, 4-hydroxydiphenoxide,
1.1'-bis(3-k-4-hydrooxyphenyl)
Cyclohexane, 4,4'-Sec-butylidene diphenol, 4-ρ-methylphenylphenol, 4.4
'-Methylcyclohexylidenephenol, 1,1゛-
Bis(3-chloro4-hydroxyphenyl)-2
-ethylbutane, 1,1"-bis(4-hydrocyphenyl)cyclohexane, 4.4'-sec-inoctylidenephenol, 4.4'-isopentylidenephenol, henzyl p-hydroxybenzoate, etc. .

Examples of salicylic acid derivatives include 4-pentadecylsalicylic acid, 3,5-di(α-methylhenzyl)salicylic acid, 3,
5-di(ter-octyl)salicylic acid, 5-octadecylsalicylic acid, 5-α-(ρ-α-methylhendylphenyl)ethylsalicylic acid, 3-α-methylbenzyl-
5-ter-octylsalicylic acid, 5-tetradecylsalicylic acid, 4-hexyloxysalicylic acid, 4-cycO
Examples include hexyloxysalicylic acid, 4-decyloxysalicylic acid, 4-dodecyloxysalicylic acid, 4-pentadecyloxysalicylic acid, 4-octadecyloxysalicylic acid, and their zinc, aluminum, calcium, copper, and lead salts. The electron-accepting compound is preferably used in an amount of 50 to 800% by weight, particularly preferably 100 to 500% by weight, of the electron-donating colorless dye. If it is less than 50% by weight, the coloring will not be sufficient, and if it is more than 800% by weight, no further effect can be expected, which is not preferable.

In addition to compound [1], as a sensitizer, JP-A-58-579
Compounds disclosed in 89, JP-A-58-87094, etc. can be used in combination.

Furthermore, a surfactant, an antistatic agent, an ultraviolet ray collector, an antioxidant, an antifoaming agent, a conductive agent, a fluorescent dye, a coloring dye, etc. may be added as necessary.

Furthermore, a color preventing agent may be added to the heat-sensitive coloring layer in order to prevent the image-printed area from decoloring and to harden the generated image. Phenol compounds, particularly hindered phenol compounds, are effective as anti-fading agents. The amount of phenolic compound used is 1 to 20% relative to the electron-accepting compound.
It is preferable to use 0% by weight, more preferably 5% by weight.
~50%.

If necessary, a back coat layer may be provided on the opposite side of the support of the heat-sensitive recording material from the heat-sensitive recording layer.

As the back coat layer, any material known as a back coat layer for heat-sensitive recording materials can be used.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited only to the Examples below.

(Example-1) 2-7nilino-3-methyl-6-dibutyl-7minofluorane as an electron-donating colorless dye, bisphenol A as an electron-accepting compound, 4'-ethoxyphenyl-4-chlorobenzyl ether as a sensitizer, 209 each to 1
009 in a 5% alkyl-modified polyvinyl alcohol (Kuraray MP-102) aqueous solution for 24 hours in a ball mill (average particle size was 0.8 μm) to obtain each dispersion.

In addition, calcium carbonate (Univer 70 manufactured by Shiraishi Kogyo Co., Ltd.)
Oil amount: 40 mN/l 0 0 9) 809 was dispersed with a 0.5% sodium hexametaphosphate solution 1609 using a homogenizer to obtain a pigment dispersion.

Electron-donating colorless dye dispersion 59, electron-accepting compound dispersion 109, 4'-
A heat-sensitive coating liquid was obtained by mixing 109 parts of the ethoxyphenyl-4-chloropenzyl ether dispersion liquid and 59 parts of the calcium carbonate dispersion liquid. This heat-sensitive coloring layer coating solution was coated on high-quality paper using a coating bar so that the dry weight of the coated layer was 59/E, and dried at 50° C. for 1 minute to obtain a heat-sensitive coloring layer.

(Example-2) Thermal sensitivity was carried out in the same manner as in Example-1 except that alkyl-modified polyvinyl alcohol (Kuraray MP-202) was used instead of the alkyl-modified polyvinyl alcohol (Kuraray MP-102) used in Example-1. A recording material was obtained (average particle size was 0.65 μm).

(Example-3) A heat-sensitive recording material was prepared in the same manner as in Example-1 except that instead of applying the heat-sensitive coloring layer on the high-quality paper in Example-1, the following undercoating liquid was applied and then the heat-sensitive coloring layer was applied. I got it.

(Preparation of undercoat paper) Baking force Orin (Ansilex; Cipro Kasei) 409 was dispersed in a 1% aqueous sodium hexametaphosphate solution 609 using a dissolver so that the average particle size was 3.0 μm. Polyvinyl alcohol (manufactured by Kuraray Co., Ltd.;
PVA-1 1 7) 249, styrene-butadiene copolymer latex (manufactured by Sumitomo Nogatax Co., Ltd.; SN307
) 8.39 was added and the dry weight was 10 s/r on high-quality paper.
d and dried to obtain an undercoated paper.

(Example-4) A heat-sensitive recording material was obtained in the same manner as in Example-3 except that the following protective layer was coated on the heat-sensitive recording material layer of Example-3.

(Protective layer) Calcium carbonate (manufactured by Shiraishi Kogyo Co., Ltd.; Brilliant-15)
29 in 5% polyvinyl alcohol (manufactured by Kuraray Co., Ltd.; PVA
-117) 509 in an aqueous solution using a dissolver, and a zinc stearate dispersion (manufactured by Chukyo Yushi Co., Ltd.; Hydrin Z-7) 109 was added to obtain a protective layer-like coating solution.

It was measured with a Hess reflection densitometer RD-918.

The protective layer-forming coating liquid was bar-coated onto the heat-sensitive coloring layer of the heat-sensitive recording material of Example 3 so that the dry weight was 0.59/rrf to form a protective layer.

(Comparative Example-1) Polyvinyl alcohol (manufactured by Kuraray Co., Ltd.; PVA-
A heat-sensitive recording material was obtained in the same manner as in Example-1 except that 105) was used.

(The dispersed particle size was 1.6 μm.) (Comparative Example-2) The same procedure was carried out as in Example-1 except that β-naphthylbenzyl ether was used instead of 4'-ethoxyphenyl-4-chloropencyl ether. A thermosensitive recording material was obtained in the same manner as in Example 1 (average particle size was 0.8 μm).

The heat-sensitive recording material obtained as described above was processed using a Kyocera thermal printing experimental device at a head voltage of 24 V and a pulse cycle of IO.
While using a pressure roll under the conditions of ms, the pulse intensity was set to 1.
．． Print at 0ms and check the print density in Table 1.

Claims (1)

[Scope of Claims] A heat-sensitive recording material having a heat-sensitive coloring layer containing at least an electron-donating colorless dye, an electron-accepting compound, and a compound represented by the following general formula [1], at least a compound represented by the general formula [1]. A heat-sensitive recording material characterized in that it is used after being atomized to an average particle size of 0.4 μm to 1.0 μm in an alkyl-modified polyvinyl alcohol aqueous solution. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [1] [In the above formula, R_1 to R_4 represent a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom. ]