JP2001121825A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a thermal recording material which controls substrate blushing, has high sensitivity, and is excellent in the storage stability of a colored image. SOLUTION: In a thermal recording material in which a thermal coloring layer usually containing a colorless or pale-colored colorable compound, a developable compound which can color the colorable compound by heating, and a sensitizer as main components is formed on a support, the developable compound contains bis(3-allyl-4-hydroxyphenyl)sulfone, and the sensitizer contains 1,2-bis(phenoxymethyl)benzene and 1,1,3-tris(2-methyl-4-hydroxy-5- cyclohexylphenyl) butane.

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 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, 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 relates to a heat-sensitive recording material comprising (1) a heat-sensitive color-forming layer comprising, as main components, a colorless compound which is usually colorless or light-colored and a color-developing compound capable of developing the color-forming compound when heated. Bis (3-allyl-4-hydroxyphenyl) sulfone as a color-developing compound,
It contains 1,2-bis (phenoxymethyl) benzene as a sensitizer, and further contains 1,1,3-tris (2-methyl-4).
-Hydroxy-5-cyclohexylphenyl) butane.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a colorless or pale-colored color-forming compound and bis (3
-Allyl-4-hydroxyphenyl) sulfone and 1,2-bis (phenoxymethyl) benzene as a sensitizer were further added to 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) A thermosensitive coloring layer is prepared by using butane as a main component, a binder as shown below, and other fillers and other additives as necessary. The amount of each used is bis (3-allyl-4-hydroxyphenyl) sulfone,
1,2-Bis (phenoxymethyl) benzene is usually 0.5 to 20 parts by weight, preferably 1 to 5 parts by weight,
1,3-Tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight. Further, in the heat-sensitive recording material of the present invention, a known or publicly known color developing compound or sensitizer other than the main component of the present invention may be used in combination.

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, bis (3-allyl-4-hydroxyphenyl) sulfone, 1,2- Bis (phenoxymethyl)
Benzene is usually 1 to 80% by weight, preferably 5 to 40% by weight, and 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane is usually 0.5% by weight.
-80% by weight, preferably 5-40% by weight, binders are usually 1-90% by weight, fillers are usually 0-80% by weight, other lubricants, surfactants, defoamers, ultraviolet absorbers and the like are Each of them is used in an arbitrary ratio, for example, usually 0 to 30% by weight (weight% is the weight ratio of each component in the thermosensitive coloring layer).

Examples of the color-forming compound that can be used 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, fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds, fluorene compounds, and the like.

The 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-anilino Fluoran, 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- (3,
4-dichloroanilino) fluorane, 3-pyrrolidino-
6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-ethoxyethylaminofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-diethylamino-7-chloroflurane Oran, 3-diethylamino-7-methylfluoran, 3-
Diethylamino-7-octylfluoran, 3- [N-
Ethyl-N- (p-tolyl) amino] -6-methyl-7
-Phenethyl fluoran and the like.

As the triarylmethane compound, for example, 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide (alias: crystal violet lactone or CVL), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylaminoindole- 3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-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-ethylcarbazole-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.

Examples of spiro compounds include 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran,
Benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indoline-2,2'- Benzopyran) and the like, as diphenylmethane compounds, for example, N-halophenyl-leuco auramine,
4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,4,5-trichlorophenylleucouramine and the like; thiazine compounds such as benzoylleucomethylene blue and p-nitrobenzoylleucomethylene blue; Examples of the fluorene-based compound include rhodamine B anilinolactam and rhodamine B-p-chloroanilinolactam, and 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.

The color-developing compound which can be used in combination 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. 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'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, Methyl bis (4-hydroxyphenyl) acetate, butyl bis (4-hydroxyphenyl) acetate,
Phenolic compounds such as benzyl bis (4-hydroxyphenyl) acetate; benzyl p-hydroxybenzoate;
-Ethyl hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, 3.5-di-α-methylbenzylsalicylic acid, etc. Aromatic carboxylic acid derivatives, aromatic carboxylic acids or polyvalent metal salts thereof, such as those commonly used in pressure-sensitive recording paper and heat-sensitive recording paper, which can be used in combination with the color developing compound, Not restricted.

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, 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.

Examples of waxes that can be used in combination include wood wax, carnauba wax, shellac, paraffin, montan wax, paraffin oxide, polyethylene wax, polyethylene oxide and the like, and higher fatty acids such as stearic acid and behenic acid. 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 diphenylsulfone and the like.

The amounts of the color developing compound and the sensitizer which can be used in combination can be in a range which does not impair the effects of the present invention, for example, bis (3-allyl-4-hydroxyphenyl) sulfone,
It is preferable that the proportions do not exceed the amounts of 1,2-bis (phenoxymethyl) benzene.

Examples of the binder which 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, alkali salt of styrene / maleic anhydride copolymer, iso (or diiso) butylene /
Water-soluble ones such as an alkali salt of a maleic anhydride copolymer or polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polystyrene, polyacrylate, polyurethane, styrene / butadiene (SB) copolymer, carboxyl And hydrophobic polymer emulsions such as styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid-based copolymer, and composite particles of colloidal silica and acrylic resin.

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

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, and phenol derivatives for imparting an antioxidant or antiaging effect. UV absorbers such as benzophenone-based compounds and benzotriazole-based compounds, various surfactants, antifoaming agents and the like are 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, bis (3-allyl-4-hydroxyphenyl) sulfone, 1,2-bis (phenoxymethyl) benzene, and 1,1,3-tris (2-methyl-4-hydroxy-) are formed by a conventional method. After pulverizing and dispersing 5-cyclohexylphenyl) butane separately in a dispersing machine such as a ball mill, an attritor, or a sand mill together with a binder or other additives as necessary (when the pulverization and dispersion are performed by a wet method) Is usually used as a medium) to prepare a coating solution for the heat-sensitive coloring layer.
1-20 g / m ^{2 by} dry weight on a support such as synthetic paper
The heat-sensitive recording material of the present invention is obtained by drying with a bar coater, a blade coater or the like (the ratio of the color-forming compound to the color-developing compound is usually 1: 1 to 1:10 in terms of dry weight). . If necessary, an intermediate layer may be provided between the thermosensitive coloring layer and the support, or an overcoat layer (protective layer) may be provided on the thermosensitive coloring layer. The intermediate layer and the overcoat layer (protective layer) are pulverized and dispersed in the same manner as in the preparation of the thermosensitive coloring layer coating solution together with a binder or other additives as necessary, and then the intermediate layer coating solution or the overcoat layer (protection layer). Layer) After being prepared as a coating solution, the coating solution is applied so that the dry weight thereof is usually about 0.1 to 10 g / m ² .

Usually, a colorless or pale-colored coloring compound, bis (3-allyl-4-hydroxyphenyl) sulfone,
1,2-bis (phenoxymethyl) benzene and 1,1,3-tris (2-methyl-4-hydroxy-5)
The heat-sensitive recording material of the present invention containing (-cyclohexylphenyl) butane has higher sensitivity and less background fog than the conventionally known materials, and is excellent in storability of recorded images.

[0021]

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 as to have an average particle size of 1 μm or less, and the solutions [A], [B], [C] and [D] were respectively obtained. A liquid was prepared. [A] solution: 3-dibutylamino-6-methyl-7-anilinofluoran 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] solution: bis (3-allyl-4-hydroxyphenyl) sulfone 25 parts 25% PVA aqueous solution 20 parts Water 55 parts [C] Liquid: 1,2-bis (phenoxymethyl) benzene 25 parts 25% PVA aqueous solution 20 parts Water 55 parts [D] Liquid: 1,1,3-tris (2- Methyl-4-hydroxy-5-cyclohexylphenyl) butane 25 parts 25% PVA aqueous solution 20 parts Water 55 parts

Next, the above-mentioned chemicals and the following chemicals are mixed at the following ratio to prepare a coating solution for the thermosensitive coloring layer, and the dry weight is 8 g on a high-quality paper having a basis weight of 50 g / m ^2.
/ M ² and dried to obtain a thermosensitive coloring layer. [A] solution 8 parts [B] solution 16 parts [C] solution 24 parts [D] solution 8 parts 50% calcium carbonate dispersion 12 parts 50% carboxylated styrene / butadiene copolymer latex 7 parts (formation of protective layer) Further, a protective layer coating solution having the following composition ratio is dried on the above-mentioned thermosensitive coloring layer at a weight of 2 g / m2.
^The resultant was coated and dried to obtain No. 2 to obtain a heat-sensitive recording material of the present invention. 40% styrene / acrylate copolymer emulsion 20 parts 5% bentonite aqueous dispersion 40 parts 30% zinc stearate dispersion 3 parts

Example 2 25% 3-dibutylamino-7- obtained by pulverization and dispersion in the same manner as in Example 1 in place of the solution [A] of Example 1
Using an (o-chloroanilino) fluoran dispersion,
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 obtained by pulverizing and dispersing in the same manner as in Example 1 in place of the solution [A] of Example 1 Using a -7-anilinofluoran dispersion, a heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1.

Example 4 Example 1 25% 3- (N-methyl-N-cyclohexylamino) -6-methyl-7 obtained by pulverizing and dispersing in the same manner as in Example 1 in place of the liquid [A]. -A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 using an anilino fluoran dispersion. Using the heat-sensitive recording material of the present invention obtained as described above, the following quality performance tests were performed.

Table 1 Quality performance test Ground 1) Color density 2) Heat resistance 3) Water resistance 4) Plasticizer resistance 5) Example 1 0.04 1.56 1.55 1.42 1.54 Example 2 0.05 1.61 1.62 1.46 1.61 Example 3 0.06 1.65 1.66 1.49 1.65 Example 4 0.05 1.62 1.63 1.46 1.46 63

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 Corporation. 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 combined with VC wrap film on both sides
a) The Macbeth reflection density of the image portion after left at room temperature for 24 hours under a load of 300 g / cm ² .

As is clear from the table, the heat-sensitive recording material of the present invention has excellent whiteness and color density of the background, and the color image shows heat resistance, water resistance and plasticizer resistance, especially water resistance and plasticizer resistance. The sex is excellent.

[0030]

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. Contains bis (3-allyl-4-hydroxyphenyl) sulfone as a color developing compound and 1,2-bis (phenoxymethyl) benzene as a sensitizer,
A heat-sensitive recording material further comprising 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane.