JP2002362035A - 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 high color developing properties and shelf stability. SOLUTION: The heat-sensitive recording material has a heat-sensitive color development layer composed mainly of a normally colorless or a pale-color color developing chemical compound, a developing chemical compound which thermally develops a color in the color developing chemical compound and a sensitize, formed on a support. In addition. this heat-sensitive recording material contains a 4,4"-bis(p-toluenesulfonyl amino carbonylamino)-diphenylmethane and 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, Additives such as lubricants to make a coating liquid, applied to paper, film, synthetic paper, etc., and record the color by the chemical reaction that occurs when one or both of the leuco dye and the developer are melted and contacted by heating Is 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 and supermarkets, and automated transportation systems has 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, little background fog, and excellent image storability.

[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 containing, 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. A thermosensitive recording material comprising 4,4'-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane as a color developing compound and dibenzoylmethane as a sensitizer. .

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a colorless compound which is usually colorless or pale, and 4,4'-
Bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane is used as a sensitizer, and dibenzoylmethane is used as a main component. Binders and other fillers and other additives as shown below are used as necessary. Thus, a thermosensitive coloring layer is prepared. In addition, 4,4 '
-Bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane [CAS Reg. No. 151882-81-4]
Can be produced based on a method described in JP-A-5-148220 or the like.

In forming the thermosensitive coloring layer in the present invention, the coloring compound is usually 1 to 50% by weight, preferably 5 to 30% by weight, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane. Is usually from 1 to 80% by weight, preferably from 5 to 40% by weight, and dibenzoylmethane is usually from 0.5 to 80% by weight, preferably from 5 to 80% by weight.
To 40% by weight, a binder is usually 1 to 90% by weight, a filler is usually 0 to 80% by weight, and other lubricants, surfactants, defoamers, ultraviolet absorbers and the like are each in an arbitrary ratio, for example, usually Each is used in an amount of 0 to 30% by weight (the weight percentage is the weight ratio of each component in the thermosensitive coloring layer). In a more preferred embodiment, in the above composition, the amount of each of the components used is such that 4,4′-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane is usually 0% by weight relative to the chromogenic compound 1. 0.5 to 20 times, preferably 1 to 5 times, and dibenzoylmethane is usually 0.5 to 20 times, preferably 1 to 5 times.
Eight times is appropriate. Further, in the heat-sensitive recording material of the present invention, a known color developing compound or a sensitizer 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.

Specific examples of further usable spiro compounds include, for example, 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran and 3-benzylspirodinaphthopyran ,
3-propylspirobenzopyran, 3-methylnaphtho-
Specific examples of diphenylmethane compounds include (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indoline-2,2'-benzopyran) and the like. Halophenyl-leuco auramine, 4,4-bis-dimethylaminophenylbenzhydryl benzyl ether, N-2,4
5-trichlorophenyl leuco auramine and the like are specific examples of thiazine compounds, such as benzoyl leucomethylene blue and p-nitrobenzoyl leu methylene blue. Specific examples of lactam compounds are, for example, rhodamine B anilino lactam and rhodamine. Bp-
Chloroanilinolactam and the like are specific examples of fluorene-based compounds, 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-diethylaminofluorenespiro (9,3 ')-6'-pyrrolidinophthalide and the like. These coloring compounds are used alone or in combination.

Also, in the present invention, 4,4'-bis (p-toluenesulfonylaminocarbonylamino)-
A color-developing compound other than diphenylmethane can be used in combination, and examples of such a color-developing compound are not particularly limited as long as they are generally used for pressure-sensitive recording paper or heat-sensitive recording paper. 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-hexylidenediphenol, 2,2'-bis- (2,5-
Dibromo-4-hydroxyphenyl) propane, 4,
4′-isopropylidenebis (2-t-butylphenol), 2,2′-methylenebis (4-chlorophenol), 4,4′-dihydroxydiphenylsulfone,
2,4'-dihydroxydiphenyl sulfone, bis (3
-Allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-isopropocodidiphenyl sulfone,
Methyl bis (4-hydroxyphenyl) acetate, bis (4
Phenolic compounds such as -hydroxyphenyl) butyl acetate and benzyl bis (4-hydroxyphenyl) acetate;
Benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, 4-
2. dimethyl hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid,
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 thermosensitive recording paper, may be mentioned. Not limited to

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. Waxes, such as waxes, synthetic fatty acids, 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, A terphenyl derivative, a sulfone derivative, or the like that is solid at room temperature and has a melting point of about 70 ° C. or more can be used.

Specific examples of waxes that can be used in combination include:
For example, wood wax, carnauba wax, shellac, paraffin, montan wax, oxidized paraffin, polyethylene wax, polyethylene oxide, etc., as specific examples of higher fatty acids, for example, stearic acid, behenic acid, etc., as specific examples of 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. are specific examples of higher fatty acid anilides, for example, stearic acid anilide, linoleic acid Specific examples of the naphthalene derivative include anilide and the like, for example, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-benzyloxynaphthalene,
Specific examples of aromatic ethers such as hydroxynaphthoic acid phenyl ester include 1,2-diphenoxyethane, 1,4-diphenoxybutane, 1,2-bis (3-methylphenoxy) ethane, 1,2 -Screw (4-
Methoxyphenoxy) ethane, 1,2-bis (3,4-
Dimethylphenyl) ethane, 1-phenoxy-2- (4
-Chlorophenoxy) ethane, 1-phenoxy-2-
Specific examples of aromatic carboxylic acid derivatives such as (4-methoxyphenoxy) ethane and the like include, for example, benzyl p-hydroxybenzoate, benzyl p-benzyloxybenzoate, dibenzyl terephthalate, etc. Specific examples of acid ester derivatives include, for example, p-toluenesulfonic acid phenyl ester,
Phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate and the like are specific examples of carbonic acid or oxalic acid diester derivatives, for example, diphenyl carbonate,
Examples of biphenyl derivatives include dibenzyl oxalate, di (4-chlorobenzyl) oxalate, and di (4-methylbenzyl) oxalate. Specific examples of the biphenyl derivative include p-benzylbiphenyl and p-allyloxybiphenyl. However, specific examples of the terphenyl derivative include, for example, m-terphenyl, and examples of the sulfone derivative include, for example, diphenyl sulfone.

The amounts of the color-developing compound and the sensitizer which can be used in combination as described above are within a range not to impair the effects of the present invention, for example, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane, diphenylmethane, A ratio in a range not exceeding the amount of benzoylmethane used is preferred.

Specific 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, Polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid, starch and derivatives thereof, 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, polyacrylate, polyurethane, styrene Hydrophobic polymer emulsions such as butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid copolymer, and composite particles of colloidal silica and acrylic resin. Can be

Specific 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.

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 abrasion and sticking, and phenol derivatives imparting an antioxidant or antiaging effect. Benzophenone-based, benzotriazole-based ultraviolet absorbers, various surfactants, defoamers and the like can be added as required.

The heat-sensitive recording material of the present invention is prepared using the above-mentioned materials by, for example, the following method. That is, first, a color-forming compound, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane, and dibenzoylmethane are separately separated by a ball mill together with a binder or other additives as necessary.
After pulverizing and dispersing with a disperser such as an attritor or a sand mill (when the pulverization and dispersion are performed by a wet method, usually water is used as a medium), the mixture is mixed to prepare a thermosensitive coloring layer coating liquid, and the paper,
A thermosensitive recording material of the present invention is obtained by coating and drying on a support such as a plastic sheet or a synthetic paper so as to have a dry weight of usually 1 to 20 g / m ² using a bar coater, a blade coater or the like.

In the heat-sensitive recording material of the present invention, 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, if necessary.
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 .

A colorless or pale-colored coloring compound,
The heat-sensitive recording material of the present invention containing 4'-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane and dibenzoylmethane has higher sensitivity, less background fog, and excellent image storability as compared with conventionally known materials. ing.

[0022]

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" indicate parts by weight, and "%" indicates% by weight.

Example 1 A mixture having the following composition was pulverized and dispersed using a sand grinder so as to have an average particle diameter of 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: 4,4′-bis (p-toluenesulfonylaminocarbonylamino) ) -Diphenylmethane 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 that the weight when dried was 8 g / m ^2, and dried to obtain a thermosensitive coloring layer. A coloring layer was obtained. [A] solution 8 parts [B] solution 16 parts [C] solution 24 parts 50% aqueous calcium carbonate dispersion 12 parts 50% carboxylated styrene / butadiene copolymer latex 7 parts (formation of protective layer) The protective layer coating solution having the above ratio was applied onto the above-mentioned thermosensitive coloring layer so that the weight when dried was 2 g / m ^2, and dried to obtain a 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 A 25% aqueous solution of 3-dibutylamino-7- (o-chloroanilino) fluorane obtained by pulverizing and dispersing in the same manner as in Example 1 was used instead of the solution [A] in Example 1. In the same manner as in Example 1, a heat-sensitive recording material of the present invention was obtained.

Example 3 25% 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilino obtained by pulverizing and dispersing in the same manner as in Example 1 except that the solution [A] was used. A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 using an aqueous dispersion of fluoran.

Example 4 A 25% aqueous solution of 3-dipentylamino-6-methyl-7-anilinofluoran obtained by pulverization and dispersion in the same manner as in Example 1 was used instead of the solution [A] in Example 1. In the same manner as in Example 1, a heat-sensitive recording material of the present invention was obtained.

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⁾ Water resistance ³⁾ Plasticizer resistance ⁴⁾ Example 1 0.05 1.48 1.39 1.46 Example 2 0.04 1.46 1 0.35 1.42 Example 3 0.05 1.53 1.41 1.50 Example 4 0.05 1.48 1.36 1.46

1) Background: The value of the uncolored portion of the sample measured with a Macbeth reflection densitometer RD-914 (Macbeth reflection density). 2) Color density: Macbeth reflection density value of an image portion printed using a thermal printer (D-805P) manufactured by Ishida Corporation. 3) Water resistance: Macbeth reflection density of an image portion after immersing a sample developed with the above printer in tap water at room temperature for 24 hours. 4) Plasticizer resistance: P is applied to the sample colored with the above printer.
0.0294MPa combined with VC wrap film on both sides
(Macbeth reflection density of an image portion after left for 24 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 has excellent whiteness of the background and excellent color density, and the color image has excellent water resistance and plasticizer resistance.

[0032]

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 thermosensitive recording system comprising a support having thereon a heat-sensitive coloring layer containing, as main components, a colorless compound which is usually colorless or pale, a color-forming compound capable of forming a color when heated, and a sensitizer. In the material, 4,4 ′ is used as a color developing compound.
A heat-sensitive recording material comprising -bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane and dibenzoylmethane as a sensitizer.