JP2002103821A - Heat sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a heat sensitive recording material having small fogging and excellent color developability and preservability. SOLUTION: The heat sensitive recording material comprises a heat sensitive color developing layer containing a normally colorless or pale color developable compound and a developable compound for color developing the developable compound in heating on a support. In this material, as the developable compound, a compound represented by formula (1) is used, and a p-toluenesulfonic acid-β-phenoxyethyl ester is contained as a sensitizer.

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. By 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 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 heat-sensitive 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 p-toluenesulfonic acid-β-phenoxyethyl ester as a sensitizer.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a colorless or light-colored color-forming compound and a compound represented by the formula (1) as a color-developing compound are used as a sensitizer, and p-toluenesulfonic acid-.beta.-phenoxyethyl Esters are the main ingredient,
Binders and other fillers as necessary, as shown below,
A thermosensitive coloring layer is prepared with other additives.

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, p-toluenesulfonic acid-β-phenoxyethyl ester is usually 0.1%.
5 to 80% by weight, preferably 5 to 40% by weight, binder 1 to 90% by weight, filler 0 to 80% by weight, other lubricants, surfactants, defoamers, ultraviolet absorbers, etc. An arbitrary ratio, for example, 0 to 30% by weight is used (% by weight is the weight ratio of each component in the thermosensitive coloring layer). As a more preferred embodiment, among the above-mentioned compositions, the compound represented by the formula (1) is used in an amount of 0.5 to 20 times, preferably 1 to 10 times the amount of the chromogenic compound 1 by weight. ~ 5
The weight ratio of p-toluenesulfonic acid-β-phenoxyethyl ester is usually 0.5 to 20 times, preferably 1 to 8 times. In the heat-sensitive recording material of the present invention, a 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 is not particularly limited as long as it is generally used for pressure-sensitive recording paper or heat-sensitive recording paper. Examples of the coloring 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.

Of these, specific examples of fluoran compounds 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) fluoran, 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-chlorofluorane, 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 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-methyl Indole-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-ethylcarbazol-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.

Further, specific examples of spiro compounds include:
For example, 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 diphenylmethane compounds, for example, N-halophenyl-leuco auramine, 4,4-bis-dimethylaminophenylbenzhydryl benzyl ether, N-2,4,5-trichlorophenyl Leuco auramines and the like, thiazine compounds such as benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue, and lactam compounds such as rhodamine B anilinolactam and rhodamine B-p-chloroanilinolactam. ,
Examples of the fluorene-based compound 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.

Examples of the color-developing compound that can be used in combination in the present invention are not particularly limited, as long as they are those generally used for pressure-sensitive recording paper or heat-sensitive recording paper. Specific examples 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 (Alias: 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′-dihydroxydiphenyl Hong,
2,4'-dihydroxydiphenyl sulfone, bis (3
-Allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone,
4-hydroxy-4'-benzyloxydiphenyl sulfone, methyl bis (4-hydroxyphenyl) acetate, butyl bis (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- Examples thereof include, but are not limited to, aromatic carboxylic acid derivatives such as di-t-butylsalicylic acid, 3.5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids and polyvalent metal salts thereof.

The sensitizers (thermofusible compounds) which can be used in combination in the present invention include, for example, waxes such as animal and vegetable waxes, synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, naphthalene derivatives, and aromatics. Use ether, aromatic carboxylic acid derivative, aromatic sulfonic acid ester derivative, carbonic acid or oxalic acid diester derivative, biphenyl derivative, terphenyl derivative, sulfone derivative, etc. which are solid at room temperature and have a melting point of about 70 ° C. or more. be able to.

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, and the like.As higher fatty acid anilides, for example, stearic acid anilide, 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, the compound represented by the formula (1) and p-toluenesulfonic acid-
A proportion within a range not exceeding the amount of β-phenoxyethyl ester used 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 products such as alkali salts of maleic anhydride copolymer, alkali salts of iso (or diiso) butylene / maleic anhydride copolymer, and polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polystyrene, polyacryl 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 wear 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.

Using the above materials, the heat-sensitive recording material of the present invention is prepared, for example, by the following method. That is, first, a coloring compound, a compound represented by the formula (1),
After p-toluenesulfonic acid-β-phenoxyethyl ester is separately pulverized and dispersed in a dispersing machine such as a ball mill, an attritor or a sand mill together with a binder or other additives as necessary (pulverization, dispersion). When using a wet method, water is usually used as a medium) to prepare a thermosensitive coloring layer coating solution, and then a paper, a plastic sheet,
1-20 g / m ^{2 by} dry weight on a support such as synthetic paper
The coating is dried by a bar coater, a blade coater or the like to obtain the heat-sensitive recording material of the present invention. If necessary, an intermediate layer may be provided between the thermosensitive coloring layer and the support, or an overcoat layer may be provided on the thermosensitive coloring layer.

Usually, a colorless or pale-colored color-forming compound, a compound represented by the formula (1), p-toluenesulfonic acid-β
The heat-sensitive recording material of the present invention containing phenoxyethyl ester in the heat-sensitive coloring layer has high sensitivity, low background fog, and excellent image storability.

[0023]

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 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] solution: p-toluenesulfonic acid-β-phenoxyethyl ester 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 is 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 is applied onto the above-mentioned thermosensitive coloring layer so that the dry weight becomes 2 g / m ² and dried to obtain the 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 In place 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 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilino instead of 3-dibutylamino-6-methyl-7-anilinofluoran of Example 1 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.

Comparative Example 1 A comparative thermosensitive recording material was obtained in the same manner as in Example 1 except that bisphenol A was used instead of the compound of the formula (1) in Example 1.

Comparative Example 2 A heat-sensitive recording material for comparison was obtained in the same manner as in Example 1 except that stearamide was used in place of p-toluenesulfonic acid-β-phenoxyethyl ester of Example 1. Table 1 shows a quality performance table of the present invention and the comparative thermosensitive recording material obtained as described above.

Table 1 Quality performance test Background 1) Color density 2) Heat resistance 3) Water resistance 4) Plasticizer resistance 5) Example 1 0.04 1.63 1.55 1.47 1.63 Example 2 0.04 1.60 1.51 1.45 1.59 Example 3 0.05 1.65 1.57 1.50 1.65 Example 4 0.04 1.64 1.56 1.49 1.49 64 Comparative Example 1 0.09 1.50 1.40 0.40 1.05 Comparative Example 2 0.04 1.40 1.30 1.12 1.10

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.
0.3kg / cm for both sides of VC wrap film
The Macbeth reflection density of the image portion after 15 hours of standing at room temperature under a load of 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 heat-sensitive color-forming layer is a color-developing compound represented by the following formula (1): With p-toluenesulfonic acid-β as a sensitizer
-A heat-sensitive recording material containing phenoxyethyl ester.