JP2003191640A - Heat sensitive recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop a heat sensitive recording material, in which little ground fogging develops and which is excellent in color developability and preservability. <P>SOLUTION: In the heat sensitive recording material, which is formed by providing a normally colorless or light-colored color forming compound and a heat sensitive color forming layer mainly including a color developing compound thermally allowing to form color in the color forming compound and a sensitizer on a support, stearoylbenzoyl methane is included. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermal recording material. More specifically, it has high sensitivity and less fog,
The present invention relates to a heat-sensitive recording material having excellent image storability.

[0002]

2. Description of the Related Art Generally, 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 mixing them together, and then adding a binder, a sensitizer, a filler and a lubricant. It is applied as a coating liquid by adding additives such as etc. to 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 is heated by heating. I will get it. A thermal printer or the like having a built-in thermal head is used for coloring the heat-sensitive recording sheet. Compared with other recording methods, this thermal recording method has (1) no noise during recording, (2) no need for development and fixing, (3) maintenance-free, (4) relatively inexpensive machine By the characteristics such as
Facsimile field, computer output, calculator field printer field, medical measurement recorder field,
It is widely used in the fields of automatic ticket vending machines and heat-sensitive recording labels.

In recent years, with the introduction of POS systems in retail stores and supermarkets and automation systems of transportation facilities, their use for labels, tickets, coupons, etc. has increased. In these applications, thermal recording materials are required to have further improved storage stability. In addition, the demand for high-speed recording has become even higher, and there is a strong demand for the development of heat-sensitive recording materials that can sufficiently support high-speed recording. Generally, if the sensitivity of heat-sensitive recording materials is improved and their thermal response is improved, the background fog and storage stability will be improved. Will come to a decline. Conventionally, various methods have been proposed in order to improve thermal stability and further improve storage stability, but none is still satisfactory.

[0004]

The objects of the present invention are as follows.
It is to solve the drawbacks of the prior art. That is, it is to provide a heat-sensitive recording material having high sensitivity, less background fog, and excellent image storability.

[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 provides (1) a thermosensitive coloring layer containing a colorless or light-colored coloring compound, a color-developing compound capable of coloring the coloring compound under heat, and a sensitizer as main components on a support. In the heat-sensitive recording material, the following formula (1) is used as a sensitizer.

[0006]

[Chemical 2] A heat-sensitive recording material containing a compound represented by (2) 4,4'-dihydroxydiphenyl sulfone or 2,4'-dihydroxydiphenyl sulfone as a color-developing compound (1) The heat-sensitive recording material described above.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a colorless or light-colored color-forming compound, a color-developing compound, and a compound represented by the formula (1) as a sensitizer are mainly used as main components and are shown below. The thermosensitive coloring layer is prepared with such a binder and other fillers and other additives as required.

In forming the thermosensitive color-developing layer in the present invention, the color-forming compound is usually 1 to 50% by weight, preferably 5 to 30% by weight, and the color-developing compound is usually 1 to 80% by weight.
Preferably 5 to 40% by weight, the compound represented by the formula (1) is usually 1 to 80% by weight, preferably 5 to 40% by weight, the binder is 1 to 90% by weight, the filler is 0 to 80% by weight, Other lubricants, surfactants, defoaming agents, ultraviolet absorbers, etc. are used in arbitrary proportions, for example, usually 0 to 30% by weight (weight% is the weight ratio of each component in the thermosensitive coloring layer). ).

The color-forming compound used in the present invention is not particularly limited as long as it is one generally used for pressure-sensitive recording paper and heat-sensitive recording paper. Examples of the color forming compound that can be used include, for example, fluorane compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds,
Examples thereof include fluorene compounds.

Specific examples of fluorane compounds that can be used include 3-diethylamino-6-methyl-7-anilinofluorane and 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- (N-ethyl-N-isobutylamino) -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-
[N-ethyl-N- (p-tolyl) amino] -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- (o-fluoroanilino) fluorane, 3-dibutylamino-7- (o
-Fluoroanilino) fluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3-diethylamino-7- (3,4-dichloroanilino) 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- 7-methylfluorane, 3-diethylamino-7
-Octylfluorane, 3- [N-ethyl-N- (p-
Tolyl) amino] -6-methyl-7-phenethylfluorane and the like.

Specific examples of triarylmethane compounds that can be used include, for example, 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-phenylindole-
3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindole-3-)
Yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3- (2-phenylindole-
3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrole-2)
-Yl) -6-dimethylaminophthalide and the like.

Specific examples of spiro compounds that can be further used include, for example, 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, and 3-benzylspirodinaphthopyran. ,
3-propyl spirobenzopyran, 3-methylnaphtho-
Examples of diphenylmethane compounds include (3-methoxybenzo) spiropyran and 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indoline-2,2'-benzopyran) as N-halophenyl-leuco. Auramine, 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,4,5-trichlorophenyl leuco auramine and the like are examples of thiazine compounds such as benzoyl leuco methylene blue,
P-nitrobenzoyl leuco methylene blue and the like are lactam compounds such as rhodamine B anilinolactam and rhodamine B-p-chloroanilinolactam, and fluorene compounds are, for example, 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 as a mixture.

The color-developing compound is not particularly limited as long as it is one generally used in pressure-sensitive recording paper and heat-sensitive recording paper. Specific examples of the color-developing compound that can be used include, for example, α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, pt-butylphenol, p-phenylphenol, 1,1-bis (p
-Hydroxyphenyl) propane, 2,2-bis- (p
-Hydroxyphenyl) propane (also known as bisphenol A or BPA), 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'-isopropylidene bis (2-t-butylphenol), 2,2'-methylenebis (4-chlorophenol), 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'- Phenolic compounds such as benzyloxydiphenyl sulfone, methyl bis (4-hydroxyphenyl) acetate, bis (4-hydroxyphenyl) butyl acetate, benzyl bis (4-hydroxyphenyl) acetate, benzyl p-hydroxybenzoate, p-hydroxy Ethyl benzoate, dibenzyl 4-hydroxyphthalate, 4-hi Dimethyl droxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-
Aromatic carboxylic acid derivatives such as t-butylsalicylic acid and 3.5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids or polyvalent metal salts thereof, etc. are generally used for pressure-sensitive recording paper and heat-sensitive recording paper. Examples include, but are not limited to, 4,4′-dihydroxydiphenyl sulfone is preferred. These color forming compounds may be used alone or as a mixture.

Examples of the sensitizer (heat-fusible compound) that can be used in the present invention include waxes such as animal and vegetable waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, naphthalene derivatives, and aromatic compounds. Use ethers, aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, carbonic acid or oxalic acid diester derivatives, biphenyl derivatives, terphenyl derivatives, sulfone derivatives, etc. that are solid at room temperature and have a melting point of about 60 ° C or higher. be able to.

Waxes that can be used in combination include, for example, wood wax, carnauba wax, shellac, paraffin, montan wax, oxidized paraffin, polyethylene wax and polyethylene oxide, and higher fatty acids include stearic acid and behenic acid. As a higher fatty acid amide,
For example, stearic acid amide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylol behenic acid amide, methylenebisstearic acid amide, ethylenebisstearic acid amide and the like, and higher fatty acid anilides include, for example, stearic acid anilide, Examples of naphthalene derivatives such as linoleic acid anilide include 1-
Benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester and the like are 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
Aromatic carboxylic acid derivatives such as-(4-methoxyphenoxy) ethane are aromatic sulfonic acid esters such as p-hydroxybenzoic acid benzyl ester, p-benzyloxybenzoic acid benzyl ester and terephthalic acid dibenzyl ester. Examples of the derivative include p-toluenesulfonic acid phenyl ester, phenylmesitylene sulfonate, and 4-methylphenylmesitylene sulfonate. Examples of the carbonic acid or oxalic acid diester derivative include, for example, carbonic acid diphenyl, oxalic acid dibenzyl ester, and oxalic acid diester. Examples of the biphenyl derivative include (4-chlorobenzyl) ester and oxalic acid di (4-methylbenzyl) ester such as p-benzylbiphenyl and p-benzylbiphenyl.
Examples include -allyloxybiphenyl and the like, examples of the terphenyl derivative include m-terphenyl, and examples of the sulfone derivative include diphenylsulfone.

The amount of the above-mentioned sensitizer that can be used in combination is preferably within a range that does not impair the effects of the present invention, for example, within a range that does not exceed the amount of the compound represented by the formula (1).

Specific examples of the binder that can be used include methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, Of polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch and its derivatives, casein, gelatin, water-soluble isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, iso (or diiso) butylene / maleic anhydride copolymer Water-soluble substances such as alkali salts or polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polystyrene, polyacrylic acid ester, polyurethane, styrene Butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene / acrylic acid ester copolymer, styrene / butadiene / acrylic acid type copolymer, composite particles of colloidal silica and acrylic resin, etc. And the hydrophobic polymer emulsion of

Specific examples of usable fillers include calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, bentonite, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, Examples thereof include polystyrene resin and urea-formalin resin.

Other additives that can be used include higher fatty acid metal salts such as zinc stearate and calcium stearate for the purpose of preventing thermal head wear and sticking, and phenol derivatives that impart an antioxidant or antiaging effect. UV absorbers such as benzophenone-based and benzotriazole-based, various surfactants, antifoaming agents and the like are added as necessary.

The heat-sensitive recording material of the present invention is prepared by using the above-mentioned material by the following method, for example. That is, according to a conventional method, a color former, a color former, and a compound represented by the formula (1) are separately dispersed together with a binder or, if necessary, other additives, a dispersing machine such as a ball mill, an attritor or a sand mill. After pulverizing and dispersing in (the water is usually used as a medium when pulverizing and dispersing is carried out in a wet state), they are mixed to prepare a thermosensitive color developing layer coating solution, which is then coated on a support such as paper, plastic sheet and synthetic paper. Usually 1 by dry weight
The heat-sensitive recording material of the present invention is obtained by coating with a bar coater, a blade coater or the like so as to have -20 g / m ² and drying.

In the heat-sensitive recording material of the present invention, an intermediate layer may be provided between the heat-sensitive color developing layer and the support, or an overcoat layer (protective layer) may be provided on the heat-sensitive color developing layer, if necessary.
The intermediate layer and the overcoat layer (protective layer) together with the above-mentioned binder or, if necessary, the above-mentioned heat-fusible compound, filler and other additives are used in the preparation of the thermosensitive coloring layer coating liquid. Similarly to the above, after pulverizing and dispersing as necessary to form a coating liquid for an intermediate layer or an overcoat layer (protective layer), the dry weight thereof is usually 0.1 to 10 g / each.
It is applied so as to be about m ² .

The heat-sensitive recording material of the present invention, which usually contains a colorless or light-colored compound, a color-developing compound and a compound represented by the formula (1), has high sensitivity and little background fog.
Excellent image storability.

[0023]

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, "parts" are parts by weight, "%" in the description of the solutions means% by weight, and the medium is water.

Example 1 (Formation of thermosensitive coloring layer) A mixture having the following composition was pulverized and dispersed by a sand grinder so as to have an average particle size of 1 μm or less, and each of the liquids [A], [B] and [B]. C] Prepare the liquid. [A] liquid: 3-dibutylamino-6-methyl-7-anilinofluorane 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] liquid: 4,4′-dihydroxydiphenylsulfone 25 parts 25% PVA aqueous solution 20 parts Water 55 parts [C] liquid: compound represented by formula (1) (melting point 70 ° C.) 25 parts 25% PVA aqueous solution 20 parts water 55 parts

Next, a thermosensitive color developing layer coating liquid was prepared by mixing in the following proportions, and coated on a high-quality paper having a basis weight of 50 g / m ^{2 so} that the dry weight was 8 g / m ² , dried and heat-sensitive. Obtain a coloring layer. [A] liquid 8 parts [B] liquid 16 parts [C] liquid 24 parts 50% calcium carbonate dispersion 12 parts 50% carboxylated styrene / butadiene copolymer latex 7 parts

(Formation of Protective Layer) A coating solution for protective layer having the following ratio is applied onto the thermosensitive color developing layer in a weight of 2 g / dry.
The heat-sensitive recording material of the present invention having a protective layer is obtained by coating and drying so as to have m ² . 40% styrene / acrylic acid ester copolymer emulsion 20 parts 5% bentonite aqueous dispersion 40 parts 30% zinc stearate dispersion 3 parts

Example 2 Instead of 3-dibutylamino-6-methyl-7-anilinofluorane of Example 1, 3-dipentylamino-6-
A thermosensitive recording material of the present invention with a protective layer is obtained in the same manner as in Example 1 except that methyl-7-anilinofluorane is used.

Example 3 Thermal recording of the present invention with a protective layer was carried out in the same manner as in Example 1 except that 2,4'-dihydroxydiphenyl sulfone was used in place of 4,4'-dihydroxydiphenyl sulfone of Example 1. Get the material.

Example 4 A thermosensitive recording material of the present invention was prepared in the same manner as in Example 1 except that 4-hydroxy-4'-isopropoxydiphenyl sulfone was used in place of 4,4'-dihydroxydiphenyl sulfone of Example 1. To get

Table 1 shows a quality performance table of the heat-sensitive recording material of the present invention obtained as described above.

Table 1 Quality performance test Background ¹⁾ Color density ²⁾ Moisture resistance ³⁾ Water resistance ⁴⁾ Plasticizer resistance ⁵⁾ Example 1 0.05 1.58 1.52 1.56 1.52 Example 2 0.04 1.58 1.51 1.56 1.52 Example 3 0.04 1.57 1.50 1.53 1.50 Example 4 0.05 1.58 1.51 1.55 1. 51

1) Background: A value (Macbeth reflection density) of the uncolored portion of the sample measured by Macbeth reflection densitometer RD-914 type. 2) Color density: Thermal printer (Ishida Co., Ltd.)
Manufactured by D-805P), the Macbeth reflection density value of the image portion printed. 3) Moisture resistance: 4 samples of color developed by the above printer
Macbeth reflection density of the image portion after standing in a humidity chamber at 0 ° C. and 90% relative humidity for 24 hours. 4) Water resistance: Macbeth reflection density of the image portion after the sample developed by the printer was immersed in tap water at room temperature for 24 hours. 5) Plasticizer resistance: The sample colored with the above printer was combined with polyvinyl chloride (PVC) wrap film on both sides and under a load of 0.3 kg / cm ² , the Macbeth reflection density of the image portion after leaving at room temperature for 24 hours .

As is apparent from the table, the heat-sensitive recording material of the present invention is excellent in the whiteness of the background and the color density, and in the color image, the moisture resistance, water resistance and plasticizer resistance are excellent.

[0034]

EFFECT OF THE INVENTION A heat-sensitive recording material having high sensitivity, little background fog and excellent image storability was obtained.

Claims (2)

[Claims] 1. A thermosensitive recording in which a thermosensitive coloring layer containing a colorless or light-colored coloring compound, a color-developing compound capable of coloring the coloring compound under heat and a sensitizer as main components is provided on a support. In the material, a sensitizer represented by the following formula (1): A heat-sensitive recording material containing a compound represented by: 2. The heat-sensitive recording material according to claim 1, which contains 4,4′-dihydroxydiphenyl sulfone or 2,4′-dihydroxydiphenyl sulfone as the color-developing compound.