JP2002240435A - Thermal recording material coloring in red - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a thermal recording material coloring in red which has high sensitivity, sustains ground blushing little and is excellent in shelf stability. SOLUTION: A thermal recording material has a constitution wherein a thermal coloring layer constituted mainly of a normally colorless or light-colored coloring compound, a color-developing compound capable of developing the color of the coloring compound in heating and a sensitizer is provided on a substrate. The thermal recording material coloring in red contains a compound expressed by Formula (1) (wherein R1 and R2 denote a 6 or lower C alkyl) as the coloring compound and a 1,2-diphenoxymethylbenzene as the sensitizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a heat-sensitive recording material. More specifically, the present invention relates to a red-colored heat-sensitive recording material having high sensitivity, low background fog, and excellent storage stability.

[0002]

2. Description of the Related Art Generally, a thermosensitive recording material is prepared by separately dispersing a developer such as a leuco dye and a phenolic substance into fine particles, and then mixing the two with a binder, a sensitizer, a filler and a lubricant. A coating liquid is prepared by adding additives such as, etc., and applied to paper, film, synthetic paper, etc., and the color record is formed by the chemical reaction that occurs when one or both of the leuco dye and the developer melts and contacts by heating. Gain. For color development of the heat-sensitive recording sheet, a thermal printer or the like having a built-in thermal head is used. Compared with other recording methods, this thermal recording method is (1) no noise during recording, (2) there is no need for development and fixing, (3) maintenance-free, (4) machine is relatively inexpensive. With features such as
Facsimile field, computer output, printer field such as calculator, medical measurement recorder field,
It is widely used in the field of automatic ticket vending machines, the field of thermal recording labels, and the like.

[0003] In recent years, with the development of POS systems in retail stores and supermarkets, and automation systems for transportation, prepaid cards for transportation and service industries, as well as receipts for labels, tickets, coupons, etc., as well as receipts, have been used. , The use for slips is increasing. Further, as for a display method, display utilization of a single color or a multicolored color using a color tone other than the black color has been advanced. Of these color tones, red is often used as a label for specially sold or discounted products. However, the normal red coloring compound is inferior in stability to the black coloring compound, and therefore, the sticking label actually used has a noticeable decrease in the background fogging and the storage stability of the background portion and the printing portion. It is. Conventionally, various methods have been proposed for improving the heat responsiveness and further improving the storage stability, but none of them have been satisfactory.

[0004]

The object of the present invention is as described above.
It is to solve the disadvantages of the prior art. That is, it is an object of the present invention to provide a red-colored heat-sensitive recording material having high sensitivity, low background fog, and excellent storage stability among color-developed color tones used as monochromatic or multicolored color elements.

[0005]

The present inventor has made various studies to achieve the above object, and as a result, completed the present invention. That is, according to the present invention, (1) a heat-sensitive color-developing layer mainly comprising a colorless or pale-colored color-forming compound, a color-developing compound capable of causing the color-forming compound to develop a color when heated, and a sensitizer is provided on a support. In the heat-sensitive recording material, the following formula (1)

[0006]

Embedded image (In the formula (1), R ₁ and R ₂ represent an alkyl group having 6 or less carbon atoms.)

A compound represented by the formula
A red-colored heat-sensitive recording material containing diphenoxymethylbenzene.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As the alkyl group having 6 or less carbon atoms in R ₁ and R ₂ of the formula (1), for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-
Butyl group, sec-butyl group, t-butyl group, n-pentyl (amino) group, isopentyl (isoamyl) group, n
-Hexyl group and the like. Specific examples of the compound represented by the formula (1) include, for example, 3-diethylamino-7-
Phenoxyfluoran, 3-dibutyramino-7-phenoxyfluoran, 3-dipentylamino-7-phenoxyfluoran, 3- (N-methyl-N-propylamino) -7-phenoxyfluoran, 3- (N-ethyl −
N-isopentylamino) -7-phenoxyfluoran and the like, which are used alone or in combination. The compound represented by the formula (1) is disclosed in JP-A-9-3092.
No. 72, it can be synthesized by a known method.

In the present invention, a color-forming compound represented by the formula (1), a color-developing compound, and 1,2-diphenoxymethylbenzene as a sensitizer are used as main components. In addition, a thermosensitive coloring layer is prepared with a filler, other additives, and the like, if necessary.

In forming the thermosensitive coloring layer in the present invention, the coloring compound represented by the formula (1) is usually from 1 to 50.
%, Preferably 5 to 30% by weight, and the color developing compound is usually 1 to 80% by weight, preferably 5 to 40% by weight,
-Diphenoxymethylbenzene is usually 0.5-80% by weight, preferably 5-40% by weight, binder 1-90% by weight, filler 0-80% by weight, other lubricants, surfactants, The foaming agent, the ultraviolet absorber and the like are used in arbitrary ratios, for example, each in an amount of 0 to 30% by weight (the weight% is the weight ratio of each component in the thermosensitive coloring layer). As a more preferred embodiment, in the above composition, the amount of the color-developing compound is usually 0.5 to 20 times, preferably 0.5 to 20 times the weight of the color-forming compound 1 represented by (1). Is 1 to 5 times, 1,
2-Diphenoxymethylbenzene is usually 0.5 to 20.
It is used in a weight ratio of 1 to 8 times, preferably 1 to 8 times.
In the heat-sensitive recording material of the present invention, a color-forming compound or a sensitizer (a heat-fusible compound) other than the main component of the present invention may be used in combination.

The color-forming compound which can be used in combination in the present invention is not particularly limited as long as it is generally used for pressure-sensitive recording paper or heat-sensitive recording paper. Specific examples include, for example, fluoran compounds, triarylmethane compounds,
Examples include spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds, and fluorene compounds.

As the fluoran compound, for example, 3-
Diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-dipentylamino-6-methyl-7-anilinofluoran, 3- (N- Methyl-N-cyclohexylamino) -6-methyl-7-anilinofluoran,
3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluoran, 3-isobutylethylamino-6-methyl-7-anilinofluoran, 3-
[N-ethyl-N- (3-ethoxypropyl) amino]
-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-hexylamino) -6-methyl-7-anilinofluoran, 3- (N-methyl-N-propylamino) -6 -Methyl-7-anilinofluoran, 3- (N
-Ethyl-N-tetrahydrofurylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-6
-Methyl-7- (p-chloroanilino) fluoran, 3
-Diethylamino-6-methyl-7- (p-fluoroanilino) fluoran, 3- (p-toluidinoethylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7 -(P-toluidino) fluoran, 3-diethylamino-7- (3,4-dichloroanilino) fluoran, 3-pyrrolidino-6-methyl-
7-anilinofluoran, 3-diethylamino-6-chloro-7-ethoxyethylaminofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3
-Diethylamino-7-chlorofluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3
-Dibutylamino-7- (o-chloroanilino) fluoran, 3-diethylamino-7- (o-fluoroanilino) fluoran, 3-dibutylamino-7- (o-fluoroanilino) fluoran, 3-diethylamino-6-
Chloro-7-methylfluoran, 3-diethylamino-
7-methylfluorane, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7-phenylfluoran, 3- (p-toluidinoethylamino)
-6-methyl-7-phenethylfluoran and the like.

As the triarylmethane compound, for example, 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide (alias: 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.

Examples of spiro compounds include 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3.3'-dichlorospirodinaphthopyran,
Benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indoline-2,2'- Benzopyran) and the like, as diphenylmethane compounds, for example, N-halophenyl-leuco auramine,
4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,4,5-trichlorophenylleucouramine and the like; thiazine compounds such as benzoylleucomethylene blue and p-nitrobenzoylleucomethylene blue; Examples of the fluorene-based compound include rhodamine B anilinoactam and rhodamine B-p-chloroanilinolactam, and examples of the fluorene-based compound include 3,6-bis (dimethylamino) fluorenespiro (9, '3) -6'-. Dimethylaminophthalide, 3,6-bis (dimethylamino) fluorenespiro (9,3 ′)-6′-pyrrolinophthalide,
3-dimethylamino-6-diethylaminofluorenespiro (9,3 ')-6'-pyrrolidinophthalide and the like. These coloring compounds are used alone or in combination.

The color-developing compound used in the present invention is not particularly limited as long as it is generally used for pressure-sensitive recording paper or heat-sensitive recording paper. Examples thereof include phenolic compounds and aromatic carboxylic acid derivatives having a phenolic hydroxyl group. , Aromatic carboxylic acids or metal salts thereof.

Specific examples of phenol compounds that can be used include, for example, α-naphthol, β-naphthol, p-octylphenol, pt-octylphenol-p-
t-butylphenol, p-phenylphenol, bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) propane (alias: bisphenol A or BPA), 2,2-bis (p-hydroxyphenyl) Butane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 4,4′-thiobisphenol, 4,4′-cyclohexylidenediphenol, 2,
2 '-(2,5-dibromo-4-hydroxyphenyl)
Propane, 4,4-isopropylidenebis (2-t-butylphenol), 2,2′-methylenebis (4-chlorophenol), 4,4′-dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone,
Bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methoxydiphenylsulfone, 4-hydroxy-4'-ethoxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy -4'-butoxydiphenylsulfone, 4-hydroxy-4'-benzyloxydiphenylsulfone, N- (4-hydroxyphenyl) -p
-Toluenesulfonamide, N- (3-hydroxyphenyl) -p-toluenesulfonamide and the like.

Specific examples of the aromatic carboxylic acid derivative or aromatic carboxylic acid include methyl bis (4-hydroxyphenyl) acetate, ethyl bis (4-hydroxyphenyl) acetate, butyl bis (4-hydroxyphenyl) acetate, Phenolic compounds such as benzyl bis (4-hydroxyphenyl) acetate and 2,4-dihydroxy-2′-methoxybenzanilide; benzyl p-hydroxybenzoate; ethyl p-hydroxybenzoate; dibenzyl 4-hydroxyphthalate; -Aromatic carboxylic acid derivatives such as -dimethyl dimethyl hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids and metals thereof Salts.

Examples of usable sensitizers (heat-fusible compounds) include waxes such as animal and plant waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, naphthalene derivatives, aromatic ethers, and aromatics. Aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives,
Carbonic or oxalic acid diester derivatives, biphenyl derivatives, terphenyl derivatives, sulfone derivatives, etc., which are solid at ordinary temperature and have a melting point of about 70 ° C. or more can be used.

Examples of the waxes that can be used in combination include wood wax, carnauba wax, shellac, paraffin, montan wax, paraffin oxide, polyethylene wax, polyethylene oxide, and the like. Examples of higher fatty acids include stearic acid and behenic acid. As higher fatty acid amides,
For example, stearic acid amide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolstearic acid amide, methylolbehenic acid amide, methylenebisstearic acid amide, ethylenebisstearic acid amide, etc., as higher fatty acid anilides, For example, stearic acid anilide, linoleic acid anilide and the like, naphthalene derivatives such as 1-benzyloxynaphthalene, 2-benzyloxynaphthalene and 1-hydroxynaphthoic acid phenyl ester, and aromatic ethers such as 1,2- Diphenoxyethane, 1,4-diphenoxybutane, 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 and the like, and aromatic carboxylic acid derivatives include, for example, benzyl p-hydroxybenzoate, benzyl p-benzyloxybenzoate, dibenzyl terephthalate and the like. However, aromatic sulfonate derivatives include, for example, p-toluenesulfonic acid phenyl ester, phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate, etc., and carbonic acid or oxalic acid diester derivatives include, for example, diphenyl carbonate, oxalic acid Dibenzyl ester, oxalic acid di (4-chlorobenzyl) ester, oxalic acid di (4-methylbenzyl) ester and the like; biphenyl derivatives such as p-benzylbiphenyl and p-allyloxybiphenyl; Derivatives, for example, m- terphenyl and the like, Examples of the sulfonic derivatives, such as diphenyl sulfone, and the like are respectively illustrated.

The amount of the color-forming compound and the sensitizer which can be used in combination is within a range not to impair the effects of the present invention, for example, the use of the color-forming compound of the formula (1) and 1,2-diphenoxymethylbenzene. Preference is given to proportions in each case not exceeding the amounts.

Examples of the binder that can be used include, for example, 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 derivatives thereof, casein, gelatin, water-soluble isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, iso (or diiso) butylene /
Water-soluble ones such as alkali salts of maleic anhydride copolymer or polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polystyrene, polyacrylate, polyurethane, styrene / butadiene (SB) copolymer, carboxylation Examples include hydrophobic polymer emulsions such as styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid copolymer, and composite particles of colloidal silica and acrylic resin.

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

Other additives that can be used include, for example, metal salts of higher fatty acids such as zinc stearate and calcium stearate for the purpose of preventing thermal head wear and sticking, and phenol derivatives imparting an antioxidant or antiaging effect. Benzophenone-based, benzotriazole-based ultraviolet absorbers, various surfactants, defoamers, etc. are added as necessary.

Using the above materials, a red-colored heat-sensitive recording material of the present invention is prepared, for example, by the following method. That is, first, a color-forming compound represented by the formula (1) according to a conventional method,
The color-developing compound and 1,2-diphenoxymethylbenzene are each separately used as a binder or, if necessary, a filler,
After pulverized and dispersed with a disperser such as a ball mill, attritor, and sand mill together with other additives, etc. (pulverization,
When the dispersion is carried out by a wet method, water is usually used as a medium) to prepare a thermosensitive coloring layer coating solution, and it is usually 1 to 20 g by dry weight on a support such as paper, plastic sheet or synthetic paper.
/ M ² with a bar coater, blade coater or the like (the ratio of the color-forming compound to the color-developing compound is preferably 1: 1 to 1:10 by dry weight ratio) and dried. A colored heat-sensitive recording material is obtained. If necessary, an intermediate layer may be provided between the thermosensitive coloring layer and the support, or an overcoat layer (protective layer) may be provided on the thermosensitive coloring layer. The intermediate layer and the overcoat layer (protective layer) are pulverized and dispersed in the same manner as in the preparation of the thermosensitive coloring layer coating solution together with a binder or other additives as necessary, and then the intermediate layer coating solution or the overcoat layer (protection layer). Layer) After the coating solution is formed, the coating solution is applied so that the dry weight is usually about 0.1 to 10 g / m ² .

The color-forming compound represented by the formula (1),
The thermosensitive recording material of the present invention containing diphenoxymethylbenzene has higher sensitivity, less background fog, and excellent storage stability as compared with conventionally known ones.

[0026]

EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" indicates parts by weight and "%" indicates% by weight.

Example 1 (Formation of a thermosensitive coloring layer) A mixture having the following composition was pulverized and dispersed using a sand grinder so that the average particle diameter became 1 μm or less, and the solutions [A], [B] and [C] were respectively obtained. ] A liquid is prepared. [A] solution: 3- (N-ethyl-N-isopentylamino) -7-phenoxyfluoran (color-forming compound of formula (1)) 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] solution: 2 , 4'-Dihydroxydiphenyl sulfone 25 parts 25% PVA aqueous solution 20 parts Water 55 parts [C] liquid: 1,2-diphenoxymethylbenzene 25 parts 25% PVA aqueous solution 20 parts Water 55 parts

Next, a thermosensitive coloring layer coating solution was prepared by mixing at the following ratios, coated on a high-quality paper having a basis weight of 50 g / m ² so that the weight when dried was 10 g / m ^2, and dried to obtain a thermosensitive coloring layer. A coloring layer is obtained. [A] liquid 8 parts [B] liquid 16 parts [C] liquid 24 parts 50% polystyrene aqueous dispersion 10 parts 50% carboxylated styrene / butadiene copolymer latex 8 parts water 12 parts (formation of protective layer) A protective layer coating solution having the following ratio is applied onto the thermosensitive coloring layer so as to have a dry weight of 2 g / m ² and dried to obtain a red coloring thermosensitive recording material of the present invention having a protective layer. 40% styrene / acrylate copolymer emulsion 20 parts 5% bentonite aqueous dispersion 40 parts 30% zinc stearate aqueous dispersion 3 parts

Example 2 The present invention having a protective layer in the same manner as in Example 1 except that 4-hydroxy-4'-isopropoxydiphenylsulfone was used in place of 2,4'-dihydroxydiphenylsulfone of Example 1. To obtain a red-colored thermosensitive recording material.

Example 3 In the same manner as in Example 1 except that butyl bis (4-hydroxyphenyl) acetate was used in place of 2,4'-dihydroxydiphenylsulfone of Example 1, the red of the present invention having a protective layer was used. A colored heat-sensitive recording material is obtained.

Example 4 In place of 3- (N-ethyl-N-isopentylamino) -7-phenoxyfluoran in Example 1, 3-dibutylamino-7-phenoxyfluoran (the coloring property of the formula (1)) Compound) was used to obtain a heat-sensitive recording material of the present invention having a protective layer in the same manner as in Example 1.

Comparative Example 1 Example 1 was repeated using 3-diethylaminobenzo [a] fluorane in place of 3- (N-ethyl-N-isopentylamino) -7-phenoxyfluoran.
In the same manner as in the above, a red-colored thermosensitive recording material for comparison is obtained.

A red-colored thermosensitive recording material for comparison was obtained in the same manner as in Example 1 except that ethylene bisstearic acid amide was used in place of 1,2-diphenoxymethylbenzene in Example 1.

Table 1 shows the quality performance tables of the present invention and the comparative red-colored thermosensitive recording material obtained as described above.

Table 1 Quality performance test Background 1) Color density 2) Heat resistance 3) Moisture resistance 4) Moisture resistance 5) Example 1 0.04 1.51 0.06 0.05 1.50 Example 20. 05 1.55 0.08 0.06 1.55 Example 3 0.04 1.52 0.06 0.05 1.52 Example 4 0.05 1.51 0.07 0.06 1.51 Compare Example 1 0.09 1.50 0.15 0.14 1.48 Comparative Example 2 0.07 1.24 0.09 0.07 0.88

1) Background: Macbeth reflection densitometer RD-9
The red density (Macbeth reflection density value) of the uncolored portion of the sample measured with a type 14. 2) Color development: Red density of a portion printed by a commercially available POS label printer (D-805P, manufactured by Ishida Co., Ltd.). 3) Heat resistance: Red density of the uncolored portion of the sample left in a thermostat at 60 ° C. for 24 hours. 4) Moisture resistance: 24 in a humidity chamber at 40 ° C. and 90% relative humidity.
Red density of the uncolored part of the sample left for a long time. 5) Moisture resistance: 24 in a humidity chamber at 40 ° C. and 90% relative humidity.
Red density of the printed part of the sample left for a long time.

As is clear from the table, the red-colored heat-sensitive recording material of the present invention has good whiteness of the background, good color density, and excellent storage stability of the background portion and the printed portion.

[0038]

As described above, a red-colored heat-sensitive recording material having high sensitivity, little background fogging and excellent storage stability was obtained.

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a support and a heat-sensitive color-forming layer mainly comprising a colorless or light-colored color-forming compound, a color-developing compound capable of forming the color-forming compound when heated, and a sensitizer as main components. In the formula (1), a color-forming compound represented by the following formula (1): (In the formula (1), R ₁ and R ₂ each represent an alkyl group having 6 or less carbon atoms).
A red-colored heat-sensitive recording material comprising 2-diphenoxymethylbenzene.