JP2002362037A - Heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive recording material which is almost free from a texture fog and shows outstanding color development properties and shelf stability. SOLUTION: The heat-sensitive recording material has a heat-sensitive color developing layer containing a normally colorless or a pale-color color-developing chemical compound and a developing chemical compound which thermally develops a color in the color developing chemical compound, formed on a support. In addition, the heat-sensitive recording material is characterized in that its developing chemical compound is a chemical compound shown in formula (1) and the sensitizer is a dibenzoylmethane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a heat-sensitive recording material. More specifically, it has high sensitivity and low background fog,
The present invention relates to a heat-sensitive recording material having excellent image storability.

[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. What you get. 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, the use of POS systems in retail stores, supermarkets, and the like and automated systems in transportation have increased the use of labels, tickets, coupons, and the like. In these applications, it is desired that the heat-sensitive recording material is further improved in storage stability. The demand for high-speed recording has further increased, and there has been a strong demand for the development of heat-sensitive recording materials that can sufficiently cope with high-speed recording. However, the drawback that background fogging generally occurs when the sensitivity of heat-sensitive recording materials is increased to improve thermal response. Is easy to appear. Conventionally, various methods have been proposed to improve the heat responsiveness and further improve the storage stability, but none of them are 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 heat-sensitive recording material having high sensitivity, less background fogging, and excellent image storage stability.

[0005]

The present inventor has made various studies to achieve the above object, and as a result, completed the present invention. That is, the present invention provides (1) a heat-sensitive color-forming layer comprising, as main components, a colorless or light-colored color-forming compound, a color-developing compound capable of coloring the color-forming compound when heated, and a sensitizer on a support. In the thermosensitive recording material, the following compound (1)

[0006]

Embedded image

The present invention also relates to a heat-sensitive recording material characterized in that the compound contains dibenzoylmethane as a sensitizer.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a colorless or pale-colored color-forming compound, a compound represented by the formula (1) as a color-developing compound, and dibenzoylmethane as a sensitizer are mainly used. The thermosensitive coloring layer is prepared by using a binder as shown in (1) and other necessary fillers and other additives. The compound represented by the formula (1) can be produced based on a method described in JP-A-10-29816.

In forming the thermosensitive color-forming layer in the present invention, the color-forming compound is usually from 1 to 50% by weight, preferably from 5 to 30% by weight, and the compound represented by the formula (1) is usually from 1 to 50% by weight.
80% by weight, preferably 5 to 40% by weight, dibenzoylmethane is usually 0.5 to 80% by weight, preferably 5 to 40% by weight.
% By weight, 1 to 90% by weight of a binder, 0 to 80% by weight of a filler, and other lubricants, surfactants, defoamers, ultraviolet absorbers, and the like in an arbitrary ratio, for example, 0 to 30% by weight, respectively. %,
(% By weight is the weight ratio of each component in the thermosensitive coloring layer). As a more preferred embodiment, among the above compositions, the compound represented by the formula (1) is used in an amount of 0.5 to 20 times the amount of the chromogenic compound 1 in terms of weight ratio.
Preferably 1 to 5 times, dibenzoylmethane is usually 0.5 times.
It is used in a weight ratio of up to 20 times, preferably 1 to 8 times. Further, in the heat-sensitive recording material of the present invention, a known color-developing 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 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 of color-forming compounds that can be used include, for example, fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds,
Fluorene compounds and the like.

Specific examples of fluoran compounds that can be used include, for example, 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-
7-anilinofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-isopentylamino)-
6-methyl-7-anilinofluoran, 3- (N-ethyl-N-isobutylamino) -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-dipentylamino-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-
[N-ethyl-N- (p-tolyl) amino] -6-methyl-7-anilinofluoran, 3-diethylamino-6
-Methyl-7- (p-toluidino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino)
Fluorane, 3-diethylamino-7- (o-fluoroanilino) fluoran, 3-dibutylamino-7- (o
-Fluoroanilino) fluoran, 3-diethylamino-7- (m-trifluoromethylanilino) 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-methylfluoran, 3-diethylamino-7
-Octylfluoran, 3- [N-ethyl-N- (p-
Tolyl) amino] -6-methyl-7-phenethylfluoran 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.

Further, specific examples of spiro compounds that can be used include, for example, 3-methylspirodinaphthopyran,
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 include diphenylmethane compounds such as N-halophenyl-leuco auramine and 4,4-bis-dimethylaminophenylbenz. Hydryl benzyl ether, N-2,4,5-
Trichlorophenyl leuco auramine and the like, as thiazine compounds, for example, benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue and the like,
Examples of lactam compounds include rhodamine B anilinolactam and rhodamine B-p-chloroanilinolactam, and examples of fluorene compounds include 3,6-
Bis (dimethylamino) fluorenespiro (9,3 ')
-6'-dimethylaminophthalide, 3,6-bis (dimethylamino) fluorenespiro (9,3 ')-6'-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorenespiro (9,3' ) -6'-pyrrolidinophthalide and the like. These coloring compounds are used alone or in combination.

In the present invention, a color-developing compound other than the compound represented by the formula (1) can be used in combination. Examples of such a color-developing compound are generally pressure-sensitive recording paper and heat-sensitive recording paper. Any of them may be used as long as they are used in the above, and there is no particular limitation. Specific examples include α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, pt-butylphenol, p-phenylphenol, 1,1-bis (p-hydroxyphenyl) propane, 2-bis-
(P-hydroxyphenyl) propane (alias: bisphenol A or BPA), 2,2-bis- (p-hydroxyphenyl) butane, 1,1-bis- (p-hydroxyphenyl) cyclohexane, 4,4′-thio Bisphenol, 4,4′-cyclo-hexylidenediphenol,
2,2′-bis- (2,5-dibromo-4-hydroxyphenyl) propane, 4,4′-isopropylidenebis (2-t-butylphenol), 2,2′-methylenebis (4-chlorophenol), 4,4'-dihydroxydiphenylphone, 2,4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl)
Sulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-benzyloxydiphenylsulfone, methyl bis (4-hydroxyphenyl) acetate, butylbis (4-hydroxyphenyl) acetate, 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- Jee
Examples include aromatic carboxylic acid derivatives such as t-butylsalicylic acid, 3.5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids and polyvalent metal salts thereof, but are not limited thereto.

In the present invention, a sensitizer (a heat-fusible compound) other than dibenzoylmethane can be used in combination. Examples of such a sensitizer (a heat-fusible compound) include animals and plants. Wax, waxes such as synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, naphthalene derivatives, aromatic ethers, aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, carbonic acid or oxalic acid diester derivatives, biphenyl derivatives, Terphenyl derivatives, sulfone derivatives, and the like that are solid at ordinary temperature and have a melting point of about 70 ° C. or more can be used.

As waxes that can be used in combination, for example, wood wax, carnauba wax, shellac, paraffin, montan wax, paraffin oxide, polyethylene wax, polyethylene oxide, etc., and as higher fatty acids, for example, stearic acid, behenic acid, etc. As higher fatty acid amides,
For example, stearic acid amide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolbehenic acid amide, methylenebisstearic acid amide, ethylenebisstearic acid amide, etc. Linoleic acid anilide and the like, as naphthalene derivatives, for example, 1-
Benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester and the like, 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
Examples of aromatic carboxylic acid derivatives include-(4-methoxyphenoxy) ethane and the like. Examples of aromatic carboxylic acid derivatives include p-hydroxybenzoic acid benzyl ester, p-benzyloxybenzoic acid benzyl ester, terephthalic acid dibenzyl ester and the like. Derivatives include, for example, p-toluenesulfonic acid phenyl ester, phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate, and the like. Carbonic acid or oxalic acid diester derivatives include, for example, diphenyl carbonate, dibenzyl oxalate, dioxalate. (4-chlorobenzyl) ester, oxalic acid di (4-methylbenzyl) ester and the like include biphenyl derivatives such as p-benzylbiphenyl and p-benzylbiphenyl.
Examples of allyloxybiphenyl and the like are terphenyl derivatives such as m-terphenyl, and examples of the sulfone derivative are diphenyl sulfone and the like.

The amounts of the color-developing compound and the sensitizer which can be used in combination are within a range not to impair the effects of the present invention, for example, within a range not exceeding the amounts of the compound represented by the formula (1) and dibenzoylmethane. Is preferred.

In the present invention, examples of the binder that can be used include, for example, methyl cellulose, methoxy cellulose,
Hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, 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, styrene /
Water-soluble materials such as alkali salts of maleic anhydride copolymers, alkali salts of iso (or diiso) butylene / maleic anhydride copolymers, or polyvinyl acetate, vinyl chloride / vinyl acetate copolymers, polystyrene, polyacrylic Acid ester, polyurethane, styrene / butadiene (SB) copolymer, carboxylated styrene / butadiene (SB)
Examples thereof include copolymers, styrene / butadiene / acrylic acid copolymers, and hydrophobic polymer emulsions such as composite particles of colloidal silica and an acrylic resin.

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

Other additives include higher fatty acid metal salts such as zinc stearate and calcium stearate for the purpose of preventing thermal head abrasion and sticking, phenol derivatives having an antioxidant or antiaging effect, and benzophenone. UV absorbers of various types, such as benzotriazole type, various surfactants, antifoaming agents and the like are added as required.

The heat-sensitive recording material of the present invention is prepared by using the above-mentioned materials by, for example, the following method. That is, first, a coloring compound, a compound represented by the formula (1),
After dibenzoylmethane is separately pulverized and dispersed in a dispersing machine such as a ball mill, an attritor, a sand mill or the like together with a binder or other additives as necessary (usually, when pulverizing and dispersing are carried out by a wet method, water is usually used. Is used as a medium) to prepare a thermosensitive coloring layer coating solution, and a bar coater, a blade coater, or the like is used on a support such as paper, a plastic sheet, or synthetic paper so that the dry weight is usually 1 to 20 g / m ^2. To obtain a heat-sensitive recording material of the present invention.

In the heat-sensitive recording material of the present invention, if necessary, an intermediate layer may be provided between the heat-sensitive coloring layer and the support, or an overcoat layer (protective layer) may be provided on the heat-sensitive coloring layer.
The intermediate layer and the overcoat layer (protective layer) are pulverized together with a binder or, if necessary, a heat-fusible compound, a filler, and other additives in the same manner as in the preparation of a thermosensitive coloring layer coating solution.
Disperse and apply to intermediate layer coating solution or overcoat layer (protective layer)
After the coating liquid, the dry weight is usually 0.1 to 10 g / m
It is applied to be about ² .

The heat-sensitive recording material of the present invention, which contains a colorless or light-colored color-forming compound, the compound represented by the formula (1), and dibenzoylmethane in the heat-sensitive color-forming layer, has high sensitivity and little background fog, and Excellent shelf life.

[0024]

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.

Example 1 A mixture having the following composition was pulverized and dispersed using a sand grinder so that the average particle size became 1 μm or less, to prepare a solution [A], a solution [B] and a solution [C], respectively. [A] solution: 3-dibutylamino-6-methyl-7-anilinofluoran 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] solution: compound of formula (1) 25 parts 25% PVA aqueous solution 20 parts Water 55 parts [C] liquid: dibenzoylmethane 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 as to have a weight of 8 g / m ² when dried, and dried to obtain a thermosensitive coloring layer. A coloring layer is obtained. [A] solution 8 parts [B] solution 16 parts [C] solution 24 parts 50% calcium carbonate dispersion 12 parts 50% carboxylated styrene / butadiene copolymer latex 7 parts (formation of protective layer) Of the protective layer coating solution consisting of 2 g / m ² when dried on the thermosensitive coloring layer.
Is applied and dried to obtain the heat-sensitive 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 dispersion 3 parts

Example 2 Instead of 3-dibutylamino-6-methyl-7-anilinofluoran of Example 1, 3-dibutylamino-7-
Using (o-chloroanilino) fluorane, a heat-sensitive recording material of the present invention having a protective layer is obtained in the same manner as in Example 1.

Example 3 Instead of 3-dibutylamino-6-methyl-7-anilinofluoran of Example 1, 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilino Using fluoran, a thermal recording material of the present invention having a protective layer is obtained in the same manner as in Example 1.

Example 4 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinoflur in place of 3-dibutylamino-6-methyl-7-anilinofluoran of Example 1. A thermal recording material of the present invention having a protective layer is obtained in the same manner as in Example 1 using orane.

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

Table 1 Quality performance test Ground ¹⁾ Color density ²⁾ Heat resistance ³⁾ Water resistance ⁴⁾ Plasticizer resistance ⁵⁾ Example 1 0.04 1.62 1.54 1.47 1.61 Example 2 0.04 1.60 1.51 1.45 1.58 Example 3 0.05 1.65 1.57 1.50 1.64 Example 4 0.04 1.64 1.56 1.49 1.49 64

1) Background: A value obtained by measuring an uncolored portion of the sample with a Macbeth reflection densitometer RD-914 (Macbeth reflection density). 2) Color density: Macbeth reflection density value of an image portion printed by a thermal printer (D-805P) manufactured by Ishida Koki Co., Ltd. 3) Heat resistance: 6 samples of color developed by the above printer
The Macbeth reflection density of the image portion after being left in a thermostat at 0 ° C. for 24 hours. 4) Water resistance: Macbeth reflection density of an image portion after immersing a sample colored with the above printer in tap water at room temperature for 24 hours. 5) Plasticizer resistance: P is applied to the sample colored with the printer.
0.0294MP on both sides of VC wrap film
a) The Macbeth reflection density of the image portion after left for 15 hours at room temperature under a load of 0.3 kg / cm ² .

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

[0034]

As described above, a heat-sensitive recording material having high sensitivity, little background fog, and excellent image storability 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. Wherein the thermosensitive coloring layer is a color-developing compound represented by the following formula (1): A heat-sensitive recording material comprising the compound of formula (I) and dibenzoylmethane as a sensitizer.