JP2001219658A - Green coloring heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a green coloring heat-sensitive recording material provided with sharpness and high contrast. SOLUTION: In a green coloring heat-sensitive recording material provided with a heat-sensitive coloring layer composed usually of a colorless of light-color coloring compound, a developing compound for coloring the coloring compound when heated and a sensitizer as main components, the coloring compound represented by formula (1) and containing a 2,4'-dihydroxy-diphenyl sulfone or a 4-hydroxy-4'-benzyl oxyydiphenyl sulfone is contained as the developing compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly, to a heat-sensitive recording material having a vivid green color.

[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, with the development of POS systems in retail stores and supermarkets, and automation systems for transportation, prepaid cards for transportation and service industries, as well as receipts for labels, tickets, coupons, etc., as well as receipts, have been used. , The use for slips is increasing. Further, as for a display method, display utilization of a single color or a multicolored color using a color tone other than the black color has been advanced. However, in those color tones, green is susceptible to the effects of contamination due to fogging or background fog when trying to increase the color developing power, and a clear and high-contrast recording material as seen in ordinary printed matter has not been obtained. .

[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 green color heat-sensitive recording material which has less background fog and has a clear and high contrast among the color development tones used as a single color or multicolor development element.

[0005]

Means for Solving the Problems The present inventors have 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 formula (1)

[0006]

Embedded image

A green-colored heat-sensitive recording material characterized by containing the compound represented by formula (2) as a color developing compound, 2,4'-dihydroxydiphenylsulfone or 4-hydroxy-4'-benzyloxydiphenylsulfone;
About.

[0008]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a color-forming compound represented by the formula (1) and 2,4'-dihydroxydiphenyl sulfone or 4-hydroxy-
A thermosensitive coloring layer is prepared by using 4'-benzyloxydiphenyl sulfone as a main component, a binder as shown below, and other sensitizers, fillers and other additives as necessary. 2,4′-dihydroxydiphenylsulfone or 4-hydroxy-4′-benzyloxydiphenylsulfone is 0.5 to 20 parts by weight, preferably 1 to 4 parts by weight, based on 1 part by weight of the color-forming compound represented by the formula (1). 1-5
Parts by weight are appropriate.

In forming the thermosensitive coloring layer in the present invention, the coloring compound represented by the formula (1) is usually from 1 to 50.
%, Preferably 5 to 30% by weight, 2,4'-dihydroxydiphenylsulfone or 4-hydroxy-4'-
Benzyloxydiphenyl sulfone is usually 1 to 80% by weight, preferably 5 to 40% by weight, and the binder is usually 1 to 90% by weight.
%, The sensitizer is usually 0.5 to 80% by weight, the filler is usually 0 to 80% by weight, and other lubricants, surfactants, defoamers, ultraviolet absorbers and the like are each in an arbitrary ratio. Usually, each is used in an amount of 0 to 30% by weight (weight% is the weight ratio of each component in the thermosensitive coloring layer).

Examples of binders 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, alkali salt of styrene / maleic anhydride copolymer, iso (or diiso) butylene /
Water-soluble ones such as alkali salts of maleic anhydride copolymer or polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polystyrene, polyacrylate, polyurethane, styrene / butadiene (SB) copolymer, carboxylation Examples include hydrophobic polymer emulsions such as styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid copolymer, and composite particles of colloidal silica and acrylic resin.

Examples of sensitizers (thermally fusible compounds) that can be used include waxes such as animal and plant waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, naphthalene derivatives, aromatic ethers and aromatics. 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.

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, methylolstearic acid amide, methylolbehenic acid amide, methylenebisstearic acid amide, ethylenebisstearic acid amide, etc., as higher fatty acid anilides, For example, stearic acid anilide, linoleic acid anilide and the like, naphthalene derivatives such as 1-benzyloxynaphthalene, 2-benzyloxynaphthalene and 1-hydroxynaphthoic acid phenyl ester, 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 and 1-phenoxy-2- (4-methoxyphenoxy) ethane are examples of aromatic carboxylic acid derivatives such as benzyl p-hydroxybenzoate, benzyl p-benzyloxybenzoate and dibenzyl terephthalate. However, aromatic sulfonate derivatives include, for example, p-toluenesulfonic acid phenyl ester, phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate, etc., and carbonic acid or oxalic acid diester derivatives include, for example, diphenyl carbonate, oxalic acid. Dibenzyl ester, oxalic acid di (4-chlorobenzyl) ester, oxalic acid di (4-methylbenzyl) ester and the like; biphenyl derivatives such as p-benzylbiphenyl and p-allyloxybiphenyl; Derivatives, for example, m- terphenyl and the like, Examples of the sulfonic derivatives, such as diphenyl sulfone, and the like are respectively illustrated.

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

Other additives that can be used include, for example, metal salts of higher fatty acids 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, etc. are added as necessary.

The green color thermosensitive 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 represented by the formula (1) according to a conventional method,
2,4′-dihydroxydiphenylsulfone or 4-hydroxy-4′-benzyloxydiphenylsulfone are each independently a binder or, if necessary, a sensitizer,
After crushing and dispersing with a dispersing machine such as a ball mill, attritor, and sand mill together with fillers and other additives, etc. (When crushing and dispersing are performed by a wet method, water is usually used as a medium), and then mixed to form a thermosensitive coloring layer. A coating solution is prepared and placed on a support such as paper, plastic sheet, synthetic paper, etc., usually at
２０20 g / m ² by a bar coater, blade coater or the like (the ratio of the coloring compound to the developing compound is preferably 1: 1 to 1:10 by dry weight ratio)
It is dried to obtain a green coloring 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 (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 the coating solution,
It is applied so that the dry weight is usually about 0.1 to 10 g / m ² .

The color-forming compound represented by the formula (1),
The green-colored heat-sensitive recording material of the present invention containing 4'-dihydroxydiphenylsulfone or 4-hydroxydi-4'-benzyloxydiphenylsulfone has less background fog and is clear and has high contrast as compared with conventionally known materials.

[0017]

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 would be 1 μm or less, to prepare a liquid [A] and a liquid [B], respectively. [A] Solution: 25 parts of a coloring compound of formula (1) (CAS No. 42530-35-8) 25 parts of 25% aqueous solution of PVA 55 parts of water [B] Solution: 25 parts of 2,4′-dihydroxydiphenylsulfone 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 white polyester having a thickness of 188 μm so as to have a dry weight of 8 g / m ^2, and dried to form a thermosensitive coloring layer. Get. [A] Liquid 8 parts [B] Liquid 16 parts 50% polystyrene dispersion liquid 12 parts 50% carboxylated styrene / butadiene copolymer latex 8 parts Water 6 parts (Formation of protective layer) Further, a protective layer having the following ratio The coating liquid is applied onto the above-mentioned thermosensitive coloring layer so as to have a dry weight of 2 g / m ² and dried to obtain a green-coloring thermosensitive 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 The green color thermosensitive recording of the present invention was performed in the same manner as in Example 1 except that 4-hydroxy-4'-benzyloxydiphenylsulfone was used in place of 2,4'-dihydroxydiphenylsulfone of Example 1. Get the material.

Example 3 A green color thermosensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the coating solution of the thermosensitive coloring layer having the following composition was used instead of the coating solution of the thermosensitive coloring layer of Example 1. [A] liquid 8 parts [B] liquid 16 parts 20% methylol stearamide dispersion 10 parts 50% carboxylated styrene / butadiene copolymer latex 8 parts

Table 1 shows the quality performance table of the green color thermosensitive recording material of the present invention obtained as described above.

Table 1 Quality performance test Background 1) Color density 2) Heat resistance 3) Moisture resistance 4) Example 1 0.03 1.50 0.03 0.06 Example 2 0.03 1.45 0.03 0.05 Example 3 0.03 1.56 0.04 0.08

1) Background: Green density value (Macbeth reflection density) of an uncolored portion of a sample measured by Macbeth reflection densitometer RD-914. 2) Color development: Card printer TH-C manufactured by Okura Electric
Macbeth reflection density of the sample developed by PS. 6) Heat resistance: Macbeth reflection density of the background of the sample left for 100 hours in a thermostat at 55 ° C. 7) Moisture resistance: Macbeth reflection density of the background of the sample left for 24 hours in a humidity chamber at 55 ° C. and a relative humidity of 90%.

As is clear from the table, the green-colored heat-sensitive recording material of the present invention has excellent whiteness and color density of the background, and excellent storage stability of the background.

[0026]

According to the present invention, a green-colored heat-sensitive recording material having less background fog and a clear and high contrast 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. In the formula (1), a color-forming compound represented by the following formula (1): Represented by 2,4'-dihydroxydiphenyl sulfone or 4-hydroxy-
A green-colored heat-sensitive recording material comprising 4'-benzyloxydiphenyl sulfone.