JPH07156558A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance the preservability of a thermal recording material by adding a color forming compd. represented by a specific formula, a compd. represented by a specific formula being a coupling compd. and 4-benzyloxy-4'-(2- methylglycidyloxy) diphenylsulfone. CONSTITUTION:3-[4-(4-pheylaminophenyl) aminophermyl] amino-6-methyl-7- chlorofluorane is added to the thermal color forming layer provided on a support. As a coupling compd., a compd. represented by formula I (wherein R1-R3 are independently hydrogen, a 1-5C alkyl group or a 2-5C alkenyl group), for example, 4,4'-sulfonyl-bis-(2arylphenol) or a compd. reresented by formula II (wherein R is a 1-4C alkyl group or a benzyl group), for example, bis (4- hydroxyphenyl)benzyl acetate is added. Further, 4-benyloxy-4'-(2 methylglycidyloxy) diphenylsufone is added.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material having a near-infrared absorbing ability which is excellent in storage stability of a color image.

[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-451403.
It was announced in No. 9 and has been put to practical use. Generally, in a heat-sensitive recording material, a leuco dye and a color developer such as a phenolic substance are separately dispersed in fine particles, and then both are mixed, and a binder, a sensitizer, a filler, a lubricant, etc. are added thereto. It is used as a coating liquid by adding a chemical agent, and is applied to a support such as paper, film, synthetic paper, etc., and color recording is made by a chemical reaction that occurs when one or both of the leuco dye and the developer melts and contacts when heated. In general, a sheet-shaped heat-sensitive recording material is prepared. A thermal printer or the like having a built-in thermal head is used for color development of such a thermal recording sheet. Compared to other recording methods, this heat-sensitive recording method is (1) no noise is generated during recording, (2) there is no need for developing and fixing, and (3) maintenance-free.
(4) Widely used in the field of facsimiles, computer output, printers such as calculators, recorders for medical measurement, automatic ticket vending machines, thermosensitive recording labels, etc. due to the fact that machines are relatively inexpensive. Has been.

Further, POS systems have been remarkably used in large-scale mass-market stores such as supermarkets and department stores, as well as in specialty stores and restaurants where chain development is being carried out, and bar codes and OCR characters displayed on products and vouchers are displayed. The method of optically reading with a scanner is rapidly growing. For this reading, a visible light source or a wavelength of 6 has been conventionally used.
A helium-neon laser with a red light of 33 nm is used, but recently, a semiconductor laser has been used. This is because the size of the device can be reduced, there are few failures, the cost is low, and in terms of performance, there is little malfunction under visible light because the oscillation wavelength of the scanner is 700-1500 nm (near infrared part). It has the advantage of being widely used. For this reason, the use of heat-sensitive recording sheets and labels having this near-infrared absorption capacity has started.

[0004]

However, a heat-sensitive recording material using a color-forming compound that develops color by heat and has a near-infrared absorbing ability is more difficult than ordinary heat-sensitive recording type sheets and labels of visible absorption type. There is a drawback in that the color images are significantly decolored or faded due to contact with water or plastic sheets or water wetting. It is an object of the present invention to overcome these drawbacks of the prior art. That is, the present invention is to provide a heat-sensitive recording material having near-infrared absorbing ability with good storability, which is unlikely to be erased or discolored due to contact of a colored image with water or plastic films.

[0005]

The present inventor has completed the present invention as a result of various studies to achieve the above object. That is, the present invention relates to (1) a thermosensitive recording material having a thermosensitive coloring layer containing a colorless or light-colored coloring compound and a color-developing compound capable of coloring the coloring compound on heating, As the color forming compound, 3- [4-
(4-phenylaminophenyl) aminophenyl] amino-6-methyl-7-chlorofluorane is used as the color-developing compound and is represented by the following formula (1) or the following formula (2).

[0006]

[Chemical 3]

(In the formula (1), R ₁ , R ₂ and R ₃ are each independently hydrogen, an alkyl group having 1 to 5 carbon atoms or 2 carbon atoms.
Represents the alkenyl group of ~ 5. )

[0008]

[Chemical 4]

(In the formula (2), R represents an alkyl group having 1 to 4 carbon atoms or a benzyl group), and further 4-benzyloxy-4 '-(2-methylglycidyloxy) diphenyl sulfone. A thermosensitive recording material characterized by containing (2) a thermosensitive recording material of the formula (1), wherein the compound of the formula (1) is 4,4′-sulfonyl-bis- (2-allylphenol), a formula (3) The thermal recording material of (1), wherein the compound of (2) is benzyl bis (4-hydroxyphenyl) acetate.

In the heat-sensitive recording material of the present invention, 3-
[4- (4-phenylaminophenyl) aminophenyl] amino-6-methyl-7-chlorofluorane and the color-developing compound of formula (1) or formula (2), 4-benzyloxy-4 ′-(2 -Methylglycidyloxy) diphenylsulfone as a main component, and a thermosensitive color-developing layer is prepared by using the following binder and other fillers and other additives as required. 3- [4- (4-phenylaminophenyl) aminophenyl] amino-6-methyl-7-
0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, of the color-developing compound of the formula (1) or formula (2) per 1 part by weight of chlorofluorane, 4-benzyloxy-4 ′-(2 -Methylglycidyloxy) diphenyl sulfone is 0.1-1
0 parts by weight, preferably 0.5 to 5 parts by weight is suitable.

In forming the thermosensitive coloring layer in the present invention, 3- [4- (4-phenylaminophenyl) aminophenyl] amino-6-methyl-7-chlorofluorane is added in an amount of 1 to 50% by weight based on the formula ( 1) or the color-developing compound of the formula (2) is 0.5 to 80% by weight, 4-benzyloxy-
4 '-(2-methylglycidyloxy) diphenyl sulfone is 0.1 to 30% by weight, for example, the color-forming compound and the color-developing compound which can be used in combination shown below are each 0 to 40% by weight, and the binder is 1 to 90% by weight. % By weight, 0 to 80% by weight of the filler and the heat-fusible compound, and other lubricants, surfactants, defoamers, UV absorbers and the like are used in arbitrary proportions.
(Wt% is the weight ratio of each component in the thermosensitive coloring layer)

Examples of the alkyl group having 1 to 5 carbon atoms in R ₁ , R ₂ and R ₃ of the above formula (1) include methyl, ethyl, n-propyl, i-propyl, n-butyl and se.
Examples thereof include c-butyl, t-butyl, n-pentyl, i-pentyl and the like. Examples of the alkenyl group having 2 to 5 carbon atoms include vinyl group, allyl group, ethylvinyl group and the like. Examples of the color-developing compound represented by the formula (1) include 4,4′-sulfonyldiphenol, 4,4′-sulfonyl-bis- (2-allylphenol) and 4-hydroxy-4′-methoxy. Diphenyl sulfone, 4-hydroxy-4'-ethoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4
-Hydroxy-4'-butoxydiphenyl sulfone and the like can be mentioned, and these can be used alone or in combination.

Examples of the alkyl group having 1 to 4 carbon atoms in R in the above formula (2) include methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl and t.
-Butyl and the like. Examples of the color-developing compound represented by the formula (2) include methyl bis (4-hydroxyphenyl) acetate, ethyl bis (4-hydroxyphenyl) acetate, bis (4-hydroxyphenyl) propyl acetate, and bis (4 -Hydroxyphenyl) butyl acetate, bis (4-
Examples thereof include hydroxyphenyl) benzyl acetate, which may be used alone or in combination.

Further, other color-forming compounds can be used in combination, examples of which are generally used for pressure-sensitive recording paper and heat-sensitive recording paper, and are not particularly limited. Specific examples include, for example, fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds,
Examples thereof include thiazine compounds.

Examples of fluoran compounds include 3-
Diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilino Fluoran, 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- (N-methyl-N-propylamino) -6-methyl-7-anilinofluorane, 3-dipentylamino-6-methyl-7-ani Rinofluorane, 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-toluidi Noethylamino)
-6-Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (p-toluidino) fluorane, 3-diethylamino-7- (o-chloroanilino)
Fluoran, 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-ani Rinofluorane, 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 and the like can be mentioned.

Examples of the triarylmethane compound include 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-dimethylaminoindole- 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-ethylcarbazole-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 can be mentioned.

Examples of the spiro compound include 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) and the like.

Examples of diphenylmethane compounds include N-halophenyl-leuco auramine, 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,4,5-trichlorophenyl leuco auramine and the like. .

Examples of the thiazine compounds include; benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue and the like.

Examples of the color-developing compounds other than the formulas (1) and (2) that can be used in combination include, for example, α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, pt-butylphenol and p-octylphenol. -Phenylphenol, 1,1'-bis (p-hydroxyphenyl)
Propane, 2,2'-bis- (p-hydroxyphenyl) propane, 2,2'-bis- (p-hydroxyphenyl) butane, 1,1'-bis- (p-hydroxyphenyl) cyclohexane, 4,4 '-Thiobisphenol, 4,4'-cyclo-hexylidene diphenol,
2,2′-bis- (2,5-dibromo-4-hydroxyphenyl) propane, 4,4′-isopropylidenebis (2-t-butylphenol), 2,2′-methylenebis (4-chlorophenol), etc. Of phenolic compounds,
Benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, 4-
Dimethyl hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, 3.
Aromatic carboxylic acid derivatives such as 5-di-α-methylbenzyl salicylic acid, aromatic carboxylic acids or polyvalent metal salts thereof, and the like which are generally used for pressure-sensitive recording paper and heat-sensitive recording paper can be mentioned. You are not limited to the ones.

Examples of binders that can be used are 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, aqueous isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, alkali salt of iso (or diiso) butylene / maleic anhydride copolymer, etc. Water-soluble or polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polystyrene, polyacrylic ester, polyurethane, styrene / butadiene SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid copolymer, colloidal silica and a hydrophobic polymer emulsion such as composite particles of the acrylic resin.

Examples of fillers that can be used are calcium carbonate, magnesium carbonate, magnesium oxide, silica,
There are white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, urea-formalin resin and the like.

Examples of the heat-fusible compound that can be used include waxes such as animal and vegetable wax, polyethylene wax, and synthetic wax, and higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, acetylated aromatic amines, and aromatic ethers. Compounds, aromatic sulfonic acid esters, biphenyl derivatives and the like that are solid at room temperature and have a melting point of about 80 ° C. or higher can be used.

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-methyl stearic acid amide, stearic acid anilide, N-methyl oleic acid amide, benzanilide, linoleic acid anilide, N-ethylcaprylic acid amide, N-butyllaurin 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-
Bis (p-methoxyphenoxy) -3-oxa-pentane, 1,4-bis (2-vinyloxyethoxy) benzene, p-biphenyl-p-tolyl ether, benzyl-
Examples of such compounds include p-methylthiophenol, phenylmesitylene sulfonate, and 4-methylphenylmesitylene sulfonate.

In addition, lubricants such as zinc stearate, calcium stearate and aluminum stearate, various surfactants, antifoaming agents, ultraviolet absorbers and the like are added as required.

The heat-sensitive recording material of the present invention is prepared using the above-mentioned material by the following method, for example. That is, 3- [4- (4-phenylaminophenyl)
Aminophenyl] amino-6-methyl-7-chlorofluorane, a color-developing compound of formula (1) or formula (2), 4-benzyloxy-4 ′-(2-methylglycidyloxy).
Diphenyl sulfone is separately pulverized and dispersed together with a binder or other additives, if necessary, in a disperser such as a ball mill, attritor, or sand mill. Prepared by mixing to prepare a thermosensitive coloring layer coating solution on a support such as paper, plastic sheet, synthetic paper, etc. by a bar coater, a blade coater, etc. so that the dry weight is usually 1 to 20 g / m ^2. The heat-sensitive recording material of the present invention is obtained by coating and coating (the ratio of the color-forming compound to the color-developing compound is usually 2: 1 to 1:10 by dry weight).

If desired, an intermediate layer may be provided between the thermosensitive color developing layer and the support, or an overcoat layer may be provided on the thermosensitive color developing layer. 3- [4 obtained by the above method
-(4-phenylaminophenyl) aminophenyl] amino-6-methyl-7-chlorofluorane, a color-developing compound of formula (1) or formula (2) and 4-benzyloxy-
The heat-sensitive recording material having a near-infrared absorbing ability of the present invention containing 4 '-(2-methylglycidyloxy) diphenyl sulfone has good storage stability of a color image.

[0028]

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. In addition, "part" in an Example shows a weight part.

Example 1 A mixture having the following composition was pulverized and dispersed using a sand grinder so as to have an average particle size of 2 μm or less to prepare a liquid [A], a liquid [B] and a liquid [C], respectively. did. [A] liquid: 3- [4- (4-phenylaminophenyl) aminophenyl] amino-6-methyl-7-chlorofluorane 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] liquid: 4, 4'-sulfonyl-bis- (2-allylphenol) 25 parts 25% PVA aqueous solution 20 parts water 55 parts [C] liquid: 4-benzyloxy-4 '-(2-dimethylglycidyloxy) diphenylsulfone 25 parts 25% PVA aqueous solution 20 parts water 55 parts

Next, the respective preparation liquids were mixed in the following proportions to prepare a heat-sensitive color developing layer coating liquid, which was coated on a high quality paper having a basis weight of 50 g / m ^{2 so} that the dry weight thereof was about 13 g / m ² . It was dried to provide a thermosensitive coloring layer. Further, 10 on the thermosensitive coloring layer.
% PVA aqueous solution was applied so that the coating amount after drying would be 3 g / m ^2, and dried to obtain the heat-sensitive recording material of the present invention. [A] liquid 6 parts [B] liquid 24 parts [C] liquid 6 parts 20% m-terphenyl dispersion 15 parts 50% calcium carbonate dispersion 20 parts 25% PVA aqueous solution 15 parts

Example 2 A 25% 4-hydroxy-4'-isopropoxydiphenyl sulfone dispersion obtained by pulverizing and dispersing in the same manner was used in place of the liquid [B] of Example 1 in the same manner as in Example 1. A heat-sensitive recording material of the present invention was obtained.

Example 3 The present invention was carried out in the same manner as in Example 1 except that the 25% 4,4′-sulfonyldiphenol dispersion liquid obtained by pulverizing and dispersing in the same manner was used in place of the liquid [B] of Example 1. A heat-sensitive recording material of was obtained.

Example 4 The same procedure as in Example 1 was carried out using a 25% methyl bis (4-hydroxyphenyl) acetate dispersion obtained by pulverizing and dispersing in the same manner as in Example 1 instead of the solution [B]. A heat-sensitive recording material of the invention was obtained.

Example 5 A 25% bis (4-hydroxyphenyl) butyl acetate dispersion obtained by similarly pulverizing and dispersing was used in place of the liquid [B] of Example 1 and the same procedure as in Example 1 was carried out. A heat-sensitive recording material of the invention was obtained.

Example 6 In the same manner as in Example 1 except that the liquid [B] of Example 1 was replaced by a 25% bis (4-hydroxyphenyl) benzyl acetate dispersion obtained by similarly pulverizing and dispersing. A heat-sensitive recording material of the present invention was obtained.

A quality performance test was conducted on the thermal recording material of the present invention obtained as described above, and the results are shown in Table 1.

[0037]

[Table 1] Table 1 Quality performance test results Color density Water resistance 1 Water resistance 2 Plasticizer resistance 1 Plasticizer resistance 2 Example 1 1.47 1.32 Yes 1.44 Yes Example 2 1.46 1. 24 Yes 1.31 Yes Example 3 1.35 1.21 Yes 1.32 Yes Example 4 1.43 1.22 Yes 1.30 Yes Example 5 1.43 1.23 Yes 1.29 Yes Example 6 1.45 1.25 Yes 1.31 Yes

Color density: The reflection density measured by a Macbeth reflection densitometer RD-914 type on the image portion printed by a thermal printer (D-805P) manufactured by Ishida Koki Co., Ltd. Water resistance 1: Macbeth reflection density in the image area after the sample developed by the printer was immersed in tap water at room temperature for 24 hours. Water resistance 2: After testing the bar code printed sample with the above printer under the same conditions as water resistance 1, it is checked whether the bar code can be read using a pen scanner (manufactured by Evic Co.) having a wavelength of 880 nm. It was Plasticizer resistance 1: PV was applied to the sample colored by the above printer.
0.3 kg / cm ² including C wrap film on both sides
Macbeth reflection density of the image part after left at 40 ° C. for 15 hours under the load of. Plasticizer resistance 2: A sample printed with a bar code by the printer was tested under the same conditions as the plasticizer resistance 1, and then the bar code was read with the pen scanner.

As is apparent from the table, the heat-sensitive recording material of the present invention has excellent color density, water resistance and plasticizer resistance.

[0040]

EFFECT OF THE INVENTION A heat-sensitive recording material having a near-infrared absorption ability with good storage stability of a color image was obtained.

Claims (3)

[Claims] 1. A thermosensitive recording material comprising a thermosensitive color-forming layer containing a colorless or light-colored compound and a color-developing compound capable of coloring the color-forming compound under heat on a support. As 3- [4- (4-phenylaminophenyl) aminophenyl] amino-6-methyl-7-chlorofluorane as the color-developing compound represented by the following formula (1)
Alternatively, a heat-sensitive recording material containing a compound of the following formula (2) and further containing 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenyl sulfone. [Chemical 1] (In the formula (1), R ₁ , R ₂ and R ₃ each independently represent hydrogen, an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms.) (In the formula (2), R represents an alkyl group having 1 to 4 carbon atoms or a benzyl group.) 2. The heat-sensitive recording material according to claim 1, wherein the compound of formula (1) is 4,4′-sulfonyl-bis- (2-allylphenol). 3. A heat-sensitive recording material according to claim 1, wherein the compound of formula (2) is benzyl bis (4-hydroxyphenyl) acetate.