JP2001310558A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a thermal recording material which shows less texture fog and has excellent coloring forming and keeping property. SOLUTION: The thermal recording material comprises a thermal color forming layer on a support, which layer contains a typically colorless or light- colored color forming compound and a developer compound which is capable of developing color in the color forming compound upon heating. The thermal recording material is characterized in that it contains N-acetyl xylidine in the thermal color forming layer.

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 heat-sensitive 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 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 thermal recording materials, N is used as a sensitizer.
A heat-sensitive recording material characterized by containing acetyl xylysine.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail. In the present invention, usually a colorless or pale-colored color-forming compound, a color-developing compound, and N-acetylxylidine as a sensitizer are used as main components, and a binder such as shown below and other fillers as necessary. A thermosensitive coloring layer is prepared by using an agent and other additives. The amount of N-acetylxylidine used is usually 0.5 to 20 parts by weight, preferably 1 to 5 parts by weight, based on 1 part by weight of the chromogenic compound. Further, in the heat-sensitive recording material of the present invention, a known sensitizer (heat-fusible compound) other than the main component of the present invention may be used in combination.

The N-acetylxylidine used in the present invention includes isomers having a melting point of 80 ° C. or higher or a mixture thereof. Specific examples of isomers include, for example, N
-Acetyl-2,3-xylysine, N-acetyl-2,
4-xylidine, N-acetyl-2,5-xylidine,
N-acetyl-2,6-xylysine, N-acetyl-
3,4-xylidine, N-acetyl-3,5-xylidine and the like.

In forming the thermosensitive coloring layer in the present invention, the coloring compound is present in an amount of 1 to 50% by weight, preferably 5 to 50% by weight.
30% by weight, the color developing compound is 1 to 80% by weight, preferably 5 to 40% by weight, and N-acetylxylysine is 0.5 to
80% by weight, preferably 5 to 40% by weight, the binder is 1 to
90% by weight, filler is 0-80% by weight, other lubricants,
Surfactants, defoamers, ultraviolet absorbers and the like are used in arbitrary proportions, for example, 0 to 30% by weight, respectively (% by weight is the weight ratio of each component in the thermosensitive coloring layer).

The color-forming compound is not particularly limited as long as it is generally used in 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.

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.

Specific examples of spiro compounds include, for example, 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, Propyl spirobenzopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6
-Nitro-8'-methoxyspiro (indoline-2,
2′-benzopyran) and the like as diphenylmethane-based compounds, for example, N-halophenyl-leukoauramine, 4,4-bis-dimethylaminophenylbenzhydryl benzyl ether, N-2,4,5-trichlorophenylleucoura As a thiazine-based compound, for example, benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue, and as a lactam-based compound, for example, rhodamine B anilinolactam,
Rhodamine B-p-chloroanilinolactam and the like are fluorene-based compounds, for example, 3,6-bis (dimethylamino) fluorenespiro (9,3 ′)-6′-dimethylaminophthalide, 3,6-bis (Dimethylamino)
Fluorene spiro (9,3 ')-6'-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorene spiro (9,3')-6'-pyrrolidinophthalide and the like. These coloring compounds are used alone or in combination.

The color-developing compound is not particularly limited as long as it is generally used in pressure-sensitive recording paper or 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 (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'-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
Aromatic carboxylic acid derivatives such as t-butylsalicylic acid, 3.5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids and polyvalent metal salts thereof are generally used for pressure-sensitive recording paper and thermosensitive recording paper. But are not limited to these.

The sensitizers (thermofusible compounds) usable in the present invention include, for example, waxes such as animal and vegetable waxes and 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 anilide, 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 amount of the sensitizer that can be used in combination is preferably in a range that does not impair the effects of the present invention, for example, a range that does not exceed the amount of N-acetylxylidine used.

Specific 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, Polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid, starch and derivatives thereof, casein, gelatin, water-soluble isoprene rubber, alkali salts 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 the filler 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 which 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. UV absorbers such as benzophenone-based and benzotriazole-based surfactants, 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 color-forming compound, a color-developing compound, and N-acetylxylidine are separately separated by a conventional method, together with a binder or other additives as necessary, using a ball mill, an attritor,
After being pulverized and dispersed by a disperser such as a sand mill (when water is used for pulverization and dispersion, water is usually used as a medium) and mixed to prepare a thermosensitive coloring layer coating solution, paper, plastic sheet, synthetic paper, etc. 1-dry weight on a support of
Coated with a bar coater, blade coater or the like so that the concentration becomes 20 g / m ² (the ratio of the color-forming compound to the color-developing compound is usually from 1: 1 to 1:10 by dry weight ratio), dried, and then heat-sensitive according to the present invention. Obtain the recording material. 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.

The heat-sensitive recording material of the present invention, which usually contains a colorless or pale-colored color-forming compound, a color-developing compound, and N-acetylxylysine, has high sensitivity, little background fog, and excellent image storability.

[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" 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 diameter became 1 μm or less, to prepare a solution [A], a solution [B] and a solution [C], respectively. [A] Liquid: 3-dibutylamino-6-methyl-7-anilinofluoran 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: N-acetyl-2,4-xylidine (melting point 129 to 130 ° C) 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) The protective layer coating solution is applied onto the 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 dispersion 3 parts

Example 2 Instead of N-acetyl-2,4-xylidine in Example 1, N-acetyl-2,5-xylidine (melting point: 142 ° C.)
To obtain a heat-sensitive recording material of the present invention having a protective layer in the same manner as in Example 1.

Example 3 A protective layer was prepared in the same manner as in Example 1 except that N-acetyl-3,4-xylidine (melting point: 99 ° C.) was used instead of N-acetyl-2,4-xylidine. To obtain the heat-sensitive recording material of the present invention.

Example 4 The present invention provided with a protective layer in the same manner as in Example 1 except that 4-hydroxy-4'-benzyloxydiphenylsulfone was used instead of 4,4'-dihydroxydiphenylsulfone of Example 1. Is obtained.

Example 5 A book having a protective layer was prepared in the same manner as in Example 1 except that bis (3-allyl-4-hydroxyphenyl) sulfone was used in place of 4,4'-dihydroxydiphenylsulfone of Example 1. The thermosensitive recording material of the invention is 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 Background 1) Color density 2) Moisture resistance 3) Water resistance 4) Plasticizer resistance 5) Example 1 0.05 1.56 1.51 1.55 1.53 Example 2 0.04 1.58 1.53 1.57 1.55 Example 3 0.05 1.56 1.51 1.55 1.53 Example 4 0.04 1.58 1.50 1.57 1. 50 Example 5 0.05 1.58 1.53 1.58 1.52

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 by a thermal printer (D-805P) manufactured by Ishida Koki Co., Ltd. 3) Moisture resistance: 4 samples of color developed by the above printer
The Macbeth reflection density of the image portion after being left in a humidity chamber at 0 ° C. and 90% relative humidity 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 whiteness and color density of the background, and in the color image, excellent in moisture resistance, 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 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. 3. The thermosensitive recording material according to claim 1, further comprising N-acetylxylidine as a sensitizer.