JPH06328848A - Thermal recording material - Google Patents

Abstract

PURPOSE:To make coloring sensitivity and shelf stability high and favorable by a method wherein in a thermal recording meterial provided with a thermal coloring layer, amorphous silica particles, carboxyl group modified polyvinyl alcohol and glyoxal are contained in a thermal coloring layer. CONSTITUTION:In a heat recording compound provided with thermal coloring layer containing a colorless or light-colored coloring compound and a developing compound which is capable of allowing the coloring compound to color at the time of heating is provided on a substrate, amorphous silica particles, carboxyl group-modified polyvinyl alcohol and glyoxal are made to contain into the thermal coloring layer. Then the thermal recording material is obtained, by a method wherein after the coloring compound, developing compound and amorphous silica particles are pulverized and scattered separately respectively along with carboxyl group modified polivynyl alcohol or the other additive at need, the glyoxal and an additive under certain circumstances is added, mexed up with each other, a thermal coloring layer coating liquid is prepared, applied onto the substrate and dried.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat-sensitive recording material.
More specifically, it relates to a heat-sensitive recording material having high color development sensitivity and good storage stability.

[0002]

2. Description of the Related Art A heat-sensitive recording material using a colorless or light-colored color-forming substance and a color-developing substance capable of coloring the color-forming substance under heat is disclosed in JP-B-43-4160 and JP-B-45-14039.
It has been widely put into practical use since it was announced in the issue. In general, a heat-sensitive recording material is prepared by separately dispersing a leuco dye and a color developing agent such as a phenolic substance in the form of fine particles, and then mixing both.
Addition of additives such as binders, sensitizers, fillers and lubricants to form a coating solution, which is applied to a support such as paper, film or synthetic paper, and heated to produce a leuco dye and a developer. One or both of them are used to obtain a color recording by a chemical reaction that occurs when they melt or come into contact with each other, and a sheet-shaped heat-sensitive recording material is usually prepared. A thermal printer or the like having a built-in thermal head is used for coloring such a thermal recording sheet. Compared with other recording methods, this thermal recording method is (1) no noise is generated during recording, (2) there is no need for development and fixing, and (3) maintenance-free. (4) Due to features such as relatively inexpensive machines,
It is widely used in the fields of computer output, calculators and other printers, medical measurement recorders, automatic ticket vending machines, and heat-sensitive recording labels.

With the spread of such automation, the demand for high-speed recording and high-density recording has increased, and it has been strongly desired to develop not only high-speed recording devices but also recording materials that can cope with this.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material having high color-developing sensitivity and good storage stability.

[0005]

The present inventors have completed the present invention as a result of earnest research to solve the above-mentioned problems. That is, the present invention provides (1) a heat-sensitive recording material comprising a support and a heat-sensitive color-forming layer containing a colorless or light-colored color-forming compound and a color-developing compound capable of coloring the color-forming compound when heated. A thermosensitive recording material characterized by containing amorphous silica fine particles, a carboxyl group-modified polyvinyl alcohol, and glyoxal in the thermosensitive coloring layer, (2) the support according to the above item (1) is a polyolefin-based or polyester-based void. The heat-sensitive recording material as described in (1) above, which is a content-type synthetic paper, (3) Amorphous silica has an average particle diameter of secondary particles of 10 μm or less, and a BET specific surface area of 10 to 150 g / m.
^2. The heat-sensitive recording material according to the above (1), which is particles having a bulk specific gravity of 50 to 300 g / l, and (4) a carboxyl group-modified polyvinyl alcohol copolymer of vinyl acetate and maleic acid or maleic acid ester. The heat-sensitive recording material according to item (1), which is a copolymer obtained by saponifying
Is provided.

The present invention will be described in detail. In the heat-sensitive recording material of the present invention, paper, plastic sheet, synthetic paper, especially polyolefin-based or polyester-based void-containing synthetic paper, etc. on a support, amorphous silica fine particles, carboxyl group-modified polyvinyl alcohol and glyoxal and The thermosensitive color-developing layer is prepared by using the (A) color-developing compound, the (B) color-developing compound and other binders, fillers, heat-fusible compounds, and surfactants as required. Amorphous silica fine particles are contained in the thermosensitive coloring layer in an amount of 5 to 7
0% by weight, preferably 10 to 40% by weight, carboxy group-modified polyvinyl alcohol is 1 to 50% by weight, preferably 5
To 20% by weight and glyoxal of 0.01% by weight or more, preferably 1 to 5% by weight, respectively.

The polyolefin-based or polyester-based void-containing synthetic paper used as a preferable support in the present invention means a polyolefin resin, a polyester resin or an inorganic pigment-containing polyolefin resin that utilizes a void (cavity) generation mechanism during stretching. It is a synthetic paper based on a stretched film such as polyester resin and containing 2 to 60% by volume of voids.

The amorphous silica fine particles used in the present invention have an average particle size of 10 μm or less, preferably 5 μm or less, and a BET specific surface area of 10 to 150 as measured by the Coulter counter method.
m ² / g preferably 10 to 50 m ² / g, the bulk density 5
Wet process amorphous silica having 0 to 300 g / l, preferably 50 to 150 g / l.

Preferred examples of the carboxyl group-modified polyvinyl alcohol in the present invention include JP-B-48-3
No. 5779, JP-A-49-6797, JP-A-53-
No. 91995 and the like, which are obtained by saponifying a copolymer of vinyl acetate and an ethylenically unsaturated dicarboxylic acid and / or an alkyl ester of an unsaturated dicarboxylic acid by a known method,
Degree of polymerization 1100 to 1800, degree of saponification 75 to 99 mol
%, The carboxylic acid group in the copolymer is 0.01 to 5 mol%
And the like. As the unsaturated dicarboxylic acid compound, maleic acid, fumaric acid, itaconic acid and their alkyl esters are preferably used. Further, the following binders can be used in combination.

(A) Examples of color-forming compounds Examples of the color-forming compounds that can be used in the present invention are those generally used for pressure-sensitive recording paper and heat-sensitive recording paper and are not particularly limited. Specific examples include the following compounds. Fluoran compounds; 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-
6-Methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isopentylamino) -6 -Methyl-7-anilinofluorane, 3
-Isobutylethylamino-6-methyl-7-anilinofluorane, 3- [N-ethyl-N- (3-ethoxypropyl) amino] -6-methyl-7-anilinofluorane, 3- (N- Ethyl-N-hexylamino) -6-methyl-7-anilinofluorane, 3-dipentylamino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-propylamino) -6- Methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurylamino) -6-methyl-7-anilinofluorane,
3-diethylamino-6-methyl-7- (p-chloroanilino) fluorane, 3-diethylamino-6-methyl-7- (p-fluoroanilino) fluorane, 3- (p
-Toluidinoethylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-
(P-Toluidino) fluorane, 3-diethylamino-
7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-
Diethylamino-7- (3,4-dichloroanilino) fluorane, 3-diethylamino-7- (o-fluoroanilino) fluorane, 3-dibutylamino-7- (o-
Fluoroanilino) fluorane, 3-pyrrolidino-6-
Methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-ethoxyethylaminofluorane,
3-diethylamino-6-chloro-7-anilinofluorane, 3-diethylamino-7-chlorofluorane, 3
-Diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7-methylfluorane, 3-
Diethylamino-7-octylaminofluorane, 3-
Diethylamino-7-phenylfluorane, 3- (p-
Toluidinoethylamino) -6-methyl-7-phenethylfluorane, etc.,

Triarylmethane compound; 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone or CVL), 3,3-bis (p-dimethylaminophenyl) Phthalide, 3- (p-dimethylaminophenyl)-
3- (1,2-dimethylaminoindol-3-yl)
Phthalide, 3- (p-dimethylaminophenyl) -3-
(2-Methylindol-3-yl) phthalide, 3-
(P-Dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3-bis (1,
2-Dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,
3-bis (9-ethylcarbazol-3-yl) -5-
Dimethylaminophthalide, 3,3- (2-phenylindol-3-yl) -5-dimethylaminophthalide, 3
-P-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like,

Spiro compounds: 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3 '
-Dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3
-Methylnaphtho- (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indoline-2,2'-benzopyran)
etc,

Diphenylmethane compounds; N-halophenyl-leukoauramine, 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,
4,5-trichlorophenyl leuco auramine, etc.,

Thiazine compounds; benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue, etc.

Lactam compounds; rhodamine B anilinolactam, rhodamine B-p-chloroanilinolactam, etc.

Fluorene compounds; 3,6-bis (dimethylamino) fluorene spiro (9,3 ')-6'-dimethylaminophthalide, 3,6-bis (dimethylamino) fluorene spiro (9,3') -6'-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorenspiro (9,3 ')-6'-pyrrolidinophthalide and the like can be mentioned. These color-forming compounds may be used alone or in admixture of two or more.

(B) Example of color-developing compound The color-developing compound is not particularly limited, as it is generally used for pressure-sensitive recording paper and heat-sensitive recording paper. Specific examples include α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, pt-butylphenol, p-phenylphenol, 1,1′-.
(P-Hydroxyphenyl) propane, 2,2'-bis (p-hydroxyphenyl) propane (also known as bisphenol A or BPA), 2,2 '-(p-hydroxyphenyl) butane, 1,1'-(p -Hydroxyphenyl) cyclohexane, 4,4'-thiobisphenol,
4,4'-Cyclohexylidene diphenol, 2,2 '
-(2,5-dibromo-4-hydroxyphenyl) propane, 4,4'-isopropylidenebis-2-t-butylphenol), 2,2'-methylenebis- (4-chlorophenol), 4,4'- Sriphonyl diphenol,
4,4'-sulfonyl-bis- (2-allylphenol), 4-hydroxy-4'-methoxydiphenyl sulfone, 4-hydroxy-4'-ethoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-butoxydiphenyl sulfone, bis (4-hydroxyphenyl) methyl acetate, bis (4-hydroxyphenyl) butyl, bis (4
Phenolic compounds such as -hydroxyphenyl) benzyl acetate, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5 Examples thereof include aromatic carboxylic acid derivatives such as -di-t-butylsalicylic acid and 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids or metal salts thereof.

In the present invention, the following binders, fillers, heat-fusible compounds and other additives are optionally used. Specific examples of chemicals that can be used for each chemical are given below. Binder: Methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch And its derivatives, casein, gelatin water-soluble isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, iso (or diiso)
Water-soluble substances such as alkali salts of butylene / maleic anhydride copolymer or ethylene / vinyl acetate copolymer, polystyrene, polyacrylic acid ester, polyurethane, styrene / butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid type copolymer, acrylonitrile /
Butadiene copolymer, ethylene / acrylic acid copolymer,
A water-soluble emulsion such as composite particles of colloidal silica and acrylic resin is used.

Filler: calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon,
Talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, urea-formalin resin and the like.

Thermofusible compounds: waxes such as animal and vegetable wax, polyethylene wax, synthetic wax, higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, acetylated aromatic amines, aromatic ether compounds, aromatic sulfones. Acid esters, biphenyl derivatives, etc. that are solid at room temperature and have a melting point of about 80 ° C or higher.

Specific examples of these compounds include caproic acid amide, capric acid amide, palmitic acid amide,
Stearic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, N-methylstearic acid amide, stearic acid anilide, N-methyloleic acid amide, benzanilide, linoleic acid anilide, N-ethylcapric acid amide, N-butyl Lauric acid amide, N-
Octadecylacetamide, N-oleinacetamide, N-oleinbenzamide, N-stearylcyclohexylamide, erucic acid amide, methylolbehenic acid amide, methylolstearic acid amide, methylenebisstearic acid amide, ethylenebisstearic acid amide, p-acetotoluidide, polyethylene Glycol,
1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-
Methoxyphenoxy) ethane, 1,2-bis (3,4-
Dimethylphenyl) ethane, 1-phenoxy-2- (4
-Chlorophenoxy) ethane, 1-phenoxy-2-
(4-methoxyphenoxy) ethane, 1- (2-methylphenoxy) -2- (4-methoxyphenoxy) ethane, terephthalic acid dibenzyl ester, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, p-benzyloxybenzoic acid benzyl ester,
p-benzylbiphenyl, m-terphenyl, 1,5-
Examples include compounds such as bis (p-methoxyphenoxy) -3-oxa-pentane, 1,4-bis (2-vinyloxyethoxy) benzene, phenylmesitylene sulfonate, and 4-methylphenylmesitylene sulfonate.
Other lubricants such as zinc stearate, calcium stearate, aluminum stearate, various surfactants,
Additives such as defoaming agents and ultraviolet absorbers are added as necessary.

The heat-sensitive recording material of the present invention is prepared by the following method using the above materials. That is, by a conventional method, a color-developing compound, a color-developing compound, and amorphous silica fine particles are separately separately dispersed with a carboxyl group-modified polyvinyl alcohol or, if necessary, other additives, in a dispersing machine such as a ball mill, attritor, or sand mill. After pulverizing and dispersing (in the case of wet dispersion, usually using water as a medium and adjusting the proportion of solid components to be 10 to 50% by weight), glyoxal and optionally further additives are added, Prepare a thermosensitive coloring layer coating solution by mixing,
For example, on a support such as a polyolefin-based or polyester-based void-containing synthetic paper, etc.
It is applied by a bar coater, a blade coater or the like so as to have g / m ² (the ratio of the color-developing compound to the color-developing compound is usually 1: 1 to 1:10 by dry weight ratio), dried, and dried according to the present invention. Obtain a thermosensitive recording material.

A heat-sensitive recording material of the present invention containing amorphous silica fine particles, a carboxyl group-modified polyvinyl alcohol and glyoxal in a heat-sensitive color forming layer formed on a support such as a polyolefin-based or polyester-based void-containing synthetic paper. Has higher color development sensitivity and better storage stability than those known in the related art.

[0024]

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In the examples, "part" indicates part by weight.

Example 1 A mixture [A] solution, a [B] solution and a [C] solution were prepared by pulverizing and dispersing a mixture having the following composition using a sand grinder so as to have an average particle size of 2 μm or less. . Liquid [A]: 3-dibutylamino-6-methyl-7-anilinofluorane 25 parts 15% Goshenal T-350 (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., maleic acid modified polyvinyl alcohol, saponification degree = 93-95 mol 1%) aqueous solution 20 parts water 55 parts [B] liquid: 4-hydroxy-4′-isopropoxydiphenylsulfone 25 parts 15% gosenal T-350 aqueous solution 20 parts water 55 parts [C] liquid: m-ter Phenyl 30 parts 25% PVA aqueous solution 20 parts Water 50 parts [D] Liquid: Nipseal E-75 (trade name, manufactured by Nippon Silica Industry Co., Ltd., amorphous silica fine particles, average particle diameter of secondary particles = 1. 5 to 2.5 μm, BET specific surface area = 30 to 50 m ² / g, bulk specific gravity = 100 to 140 g / l) 30 parts 25% PVA aqueous solution 10 parts water 60 parts

Next, the respective preparation liquids are mixed in the following proportions to prepare a thermosensitive color developing layer coating liquid, and a polyolefin type void-containing synthetic paper (trade name: YUPO FPG-110, thickness = 1).
A thermosensitive recording material of the present invention was obtained by applying it on 10 μm, manufactured by Oji Yuka Synthetic Paper Co., Ltd. so that the dry weight was about 10 g / m ² . [A] liquid 6 parts [B] liquid 12 parts [C] liquid 20 parts [D] liquid 25 parts 15% Gohsenal T-350 aqueous solution 10 parts 35% zinc stearate dispersion liquid 6 parts 40% glyoxal aqueous solution 1 part water 20 Department

Example 2 A polyolefin-based void-containing synthetic paper YUPO SGG-80 (trade name, manufactured by Oji Yuka Synthetic Paper Co., Ltd., thickness = 80 μm) was used in place of the synthetic paper of Example 1. A thermal recording material of the present invention was obtained in the same manner as in Example 1.

Example 3 In place of the synthetic paper of Example 1, polyolefin void-containing synthetic paper Pearl-SS (trade name, manufactured by Toyobo Co., Ltd., thickness = 50 μm) was used in the same manner as in Example 1. A heat-sensitive recording material of the present invention was obtained.

Example 4 In the same manner as in Example 1 except that the synthetic paper of Example 1 was replaced with polyolefin void-containing synthetic paper Pearl-SL (trade name, manufactured by Toyobo Co., Ltd., thickness = 110 μm). A heat-sensitive recording material of the present invention was obtained.

Example 5 KL-1 was used in place of the Gohsenal T-350 of Example 1.
18 (trade name, manufactured by Kuraray Co., Ltd., polyvinyl alcohol modified with itaconic acid, saponification degree = 95.5 to 98.5 mol
%) Was used in the same manner as in Example 1 to obtain a heat-sensitive recording material of the present invention.

Example 6 KL-3 was used instead of Gohsenal T-350 of Example 1.
18 (trade name, manufactured by Kuraray Co., Ltd., itaconic acid-modified polyvinyl alcohol, saponification degree = 85 to 90 mol%) was used to obtain a thermosensitive recording material of the present invention in the same manner as in Example 1.

Example 7 Example 1 Using a 25% 4,4'-sulfonyl-bis (2-allylphenol) dispersion obtained by pulverizing and dispersing in the same manner as in Example 1 [B], Example 1 was used. A thermal recording material of the present invention was obtained in the same manner as in.

Example 8 In place of the synthetic paper of Example 1, polyester void-containing synthetic paper, Crisper G-7911 (trade name, manufactured by Toyobo Co., Ltd., thickness = 50 μm) was used. A thermal recording material of the present invention was obtained in the same manner as in.

Example 9 A polyester type void-containing film, Melinex 339 (trade name, manufactured by ICI Japan Co., Ltd., thickness = 50 μm) was used in place of the synthetic paper of Example 1. A thermal recording material of the present invention was obtained in the same manner as in Example 1.

Example 10 Instead of the synthetic paper of Example 1, a polyester-based void-containing film, Lumirror E63 (trade name, manufactured by Toray Industries, Inc.,
(Thickness = 50 μm) and in the same manner as in Example 1 to obtain a heat-sensitive recording material of the present invention.

Using the heat-sensitive recording material of the present invention and the heat-sensitive recording material for comparison obtained as described above, the following quality performance test was carried out.

[0037]

[Table 1] Table 1 Quality performance test Color density 1) Color density 2) Heat resistance 3) Moisture resistance 4) Fingerprint resistance 4) Example 1 1.24 1.31 1.27 1.30 1.11 Example 2 1.24 1.31 1.27 1.30 1.11 Example 3 1.25 1.33 1.30 1.32 1.14 Example 4 1.24 1.32 1.28 1.31 1 .12 Example 5 1.23 1.34 1.33 1.34 1.25 Example 6 1.24 1.31 1.30 1.31 1.18 Example 7 1.22 1.35 1.35 1.35 1.34 Example 8 1.24 1.32 1.26 1.30 1.12 Example 9 1.22 1.30 1.28 1.30 1.12 Example 10 1.23 1. 30 1.27 1.29 1.11

1) Color density Using a thermal head printer manufactured by Matsushita Electronic Parts Co., Ltd., voltage = 20 V, pulse cycle = 5 ms. A sample was printed under the condition of pulse width = 1.0 ms and the density was measured by a Macbeth reflection densitometer (RD-914).
Value measured by type). 2) Color density Under the same printing conditions as above, pulse width = 1.2
A value obtained by printing the sample under the condition of ms and measuring the density with a Macbeth reflection densitometer. The printed sample was used for the storability test. 3) Heat resistance The sample developed by the printing device is 60 ℃.
The print density measured with a Macbeth reflection densitometer after being left in the incubator for 24 hours. 4) Moisture resistance 40 times the color developed by the printing device
Printing density measured with a Macbeth reflection densitometer after being left in a humidity chamber at ℃ and relative humidity of 90% for 24 hours. 5) Fingerprint resistance The print density measured by Macbeth reflection density after the same conditions as the humidity resistance test were performed by pressing the fingertip with the oil on the nose against the sample developed by the printing device.

As is clear from Table 1, the heat-sensitive recording material of the present invention has a high color density and has good storage stability such as heat resistance, moisture resistance and fingerprint resistance.

[0040]

EFFECT OF THE INVENTION A thermosensitive recording material having high color development sensitivity and good storage stability was obtained.

Claims (4)

[Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive coloring layer containing a colorless or pale color-developing compound and a color-developing compound capable of coloring the color-forming compound when heated. Thermosensitive recording material characterized by containing amorphous silica fine particles, carboxyl group-modified polyvinyl alcohol and glyoxal 2. The heat-sensitive recording material according to claim 1, wherein the support is a polyolefin-based or polyester-based void-containing synthetic paper. 3. Amorphous silica fine particles are secondary particles having an average particle diameter of 10 μm or less and a BET specific surface area of 10 to 150 g /
The thermal recording material according to claim 1, wherein the particles have a value of m ² and a bulk specific gravity of 50 to 300 g / l. 4. The heat-sensitive recording material according to claim 1, wherein the carboxyl group-modified polyvinyl alcohol is obtained by saponifying a copolymer of vinyl acetate and an ethylenically unsaturated dicarboxylic acid and / or an ethylenically unsaturated dicarboxylic acid ester.