JPS58102794A - Heat-sensitive recording body - Google Patents

Abstract

PURPOSE:To manufacture the heat-sensitive recording body, the sensitivity of color formation therefrom is high, the degree of whiteness thereof is high and coloring to the foundation thereof is little, by using a polyvinyl alcohol derivative containing a sulfonic group or a sulfuric group as a binding agent. CONSTITUTION:The polyvinyl alcohol derivative containing the sulfonic groups or the sulfuric groups represented by a formula (X are alkaline metals, such as H, ammonium, sodium, etc.; m and n are integers; K are 1-4; R are H or CH3) is used as the binding agent. The titled thermo-sensitive recording body is shaped by a color forming layer containing said binding agent and colorless or light-colored leuco dyes and electron acceptors color-forming said dyes when heating. It is preferable that the content of the sulfonic groups or the sulfuric groups in the polyvinyl alcohol derivative containing said sulfonic groups or sulfuric groups is within the range of 0.5-20mol%. Other water-soluble high molecules can also be used jointly as the binding agent besides said derivative.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material with improved color development characteristics, whiteness, and background coloring.

In the present invention, the heat-sensitive recording material includes a leuco dye that develops a deep color when it comes into contact with an electron acceptor, which is normally colorless or light in color, an electron acceptor such as an organic acid, a phenolic compound, a binder, and color development sensitivity. sensitizer to control and other contamination prevention and storage improvement.

A composition consisting of auxiliary materials added for the purpose of improving coating properties, preventing adhesion to a thermal head, etc. is coated on a support.

Thermal recording paper has become widely used in facsimile machines, combiator machines, printers for calculators, thermal pen recorders for medical industrial measuring instruments, and other applications, and its characteristics include: - It is like plain paper and has a high degree of whiteness. ■ Excellent paper quality such as stiffness and tear strength 9 dimensional stability; ■ Color development sensitivity suitable for the machine; ■ Excellent compatibility with thermal heads, i.e., the ability to prevent dust from entering the thermal head. It is required to have little adhesion, no sticking, little wear on the thermal head, and (5) good storage stability.

In recent years, there has been an increasing demand for faster information processing, and thermal recording methods are also moving toward higher speeds.The speeding up of thermal recording methods is largely due to improved technology, especially in thermal heads; Increasing the sensitivity of recording paper is also one of the major factors, and various methods are being used to increase the sensitivity of thermal recording paper. For example, a thermofusible sensitizer such as a higher fatty acid amide is added to lower the coloring temperature by lowering the melting point.

The reaction area is increased by reducing the dispersed particle size of leuco dye, electron acceptor, sensitizer, etc. Heat-sensitive recording paper is smoothed using a super calender, gloss calender, etc. to improve the smoothness of the recording layer surface and improve layering properties with the thermal head. For example, dye density can be increased to improve color production.

Although these methods can increase the sensitivity of thermal recording paper to some extent, they also have the disadvantage that other properties are impaired. In other words, the whiteness decreases.As a result of intensive studies to improve the above-mentioned drawbacks, the present inventors have found that by using a polyvinyl alcohol derivative containing a sulfone group or a sulfuric acid group as a binding agent, the coloring sensitivity is high and the whiteness is low. It has been found that a heat-sensitive recording material with high background coloration can be obtained. Examples of the polyvinyl alcohol derivative containing a sulfone group or a sulfuric acid group used in the present invention include, for example.

(1) A polymerizable monomer having a sulfonic group such as vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, sulfopropyl methacrylate 4% or their respective salts is copolymerized with vinyl acetate, and methanol alcohol, ethyl alcohol, etc. For example, vinyl sulfo/acid or a salt thereof is represented by formula [1].

(2) It is obtained by treating polyvinyl alcohol with bromine, iodine, etc. and then heating it in an acidic sodium sulfite aqueous solution, and is represented by the following formula [1].

(8) It is called sulfuric acid esterified polyvinyl alcohol and is expressed by the formula [■] obtained by heating polyvinyl alcohol in a concentrated aqueous sulfuric acid solution.

(4) Stability in which a carbon atom in the main chain of the molecule and a highly hydrophilic sulfone group are bonded via a hydrophobic alkyl chain having 1 to 4 carbon atoms so that hydrophilicity and hydrophobicity are balanced. A polyvinyl alcohol derivative represented by formula [IV] with good properties.

φ) A polyvinyl alcohol derivative represented by the formula [v] in which the carbon atom of the main chain of the molecule and the sulfone group are bonded via a COO group and an alkyl chain in the same way as in (4).

ivy In addition, in the above-mentioned formula, X is hydrogen or ammonium.

Or an alkali metal such as sodium.

m and n are arbitrary integers, and represent integers from 1 to 4.

R represents hydrogen or CH8.

The content of sulfone groups or sulfate groups in the polyvinyl alcohol enzyme conductor containing sulfone groups or sulfate groups of the present invention is 0.
．． The range of 5 to 20 moles is desirable.The reason is 0.5
It goes without saying that if the molar value is less than 20 molar, the color development sensitivity as a thermosensitive recording material is insufficient, and if the molar value is more than 20 molar, high-quality polyvinyl alcohol containing sulfonic or sulfuric acid groups can be derived with little coloration that can withstand practical use. Examples of water-soluble polymers that can be used in combination include cellulose derivatives such as methylcellulose, hydroxyethylcellulose, and carboxymethylcellulose, oxidized starch, and cationic starch.

Hydroxyethyl travel powder, hydroxypropyl starch.

Phosphated starch, carboxy-methyl starch.

Starch conductors such as dialdehyde starch, casein, gum arabic, gelatin, polyvinyl alcohol.

Polyvinylpyrrolidone, polyacrylamide, alkali salts/ammonium salts of styrene maleic anhydride/acid copolymer, alkali salts of methyl vinyl ether maleic anhydride copolymer, etc. are used.

The colorless leuco dye used in the present invention is 1, for example, triphenylmethane-based 8,8-bis-
(p-dimethylaminophenyl)phthalide, 3,8-
Bis-(p-dimethylamino7edimethylaminophenyl)-6-dimethylaminophenyl, 4-hydrogine-
4'-dimethylaminotrinoenylmethane lactone, 4
・4'-bisdihydroxy-8,8-bisdiaminotriphenylmethanelacty, etc., and fluoran-based 8-
Cyclohexylamino-6-chlorofluorane, 8-diethylamine-7-cybenzylaminofluorane.

3-diethyl 7mi/-6-methyl-7-chlorofluorane, 8-diethylamino-6-methyl-7-anilinofluorane, 8,7-bisdiethylaminofluorane, 8
-diethylamino-7-methoxyfluorane, 8-diethylamine-7-chloroanilinofluorane, 8-diethylamino-6-methyl-7-butylanilinofluorane, 8-(N-ethyl-p-tolylamino)-6 −
Methyl-7-anilinofluorane, 8-diethylaminone-based 8-methyl-di-β-naphthospiropyran.

Lamin series, rhodamine lactam series, fetch horse mackerel series,
Leuco dyes such as phenoxazine are also used, but 1
The present invention is not limited to these representative examples.

Electron acceptors used in the present invention include inorganic acidic substances such as acid clay, kaolin, zeolite, silicon oxide, and aluminum silicate; shiulic acid, maleic acid, benzoic acid;
Organic acids such as salicylic acid and gallic acid and their metal salts can also be used, but phenolic compounds are preferred because they have low water solubility, a sharp melting point of 70°C or higher, and excellent miscibility with leuco dyes. be. For example, 4-ter
t-butylphenol, 4-phenylphenol, 2.
2-bis(4-hydroxyphenyl)furopane, 2.2
-bis(4-hydroxyphenyl)-n-hebuta/, 4
・4'-isopropylidene bis (2-chlorophenol), 4-4'-isopropylidene less (2-methylphenol), 4,4'-ethylene bis (2). Also, two or more of these electron acceptors Mixed use is also possible, but the present invention is not limited to these representative examples.

(Improved sensitivity of thermal recording paper, improved storage stability, improved whiteness,
Rough-in wax, microcrystalline wax, and carnano wax are used for the purpose of preventing adhesion to thermal heads and improving coating properties.

Polyethylene wax, polypropylene wax.

Waxes such as montanic acid wax and higher fatty acid amides; aromatic acid ester derivatives such as benzoic acid ester derivatives, isophthalic acid ester derivatives, and terephthalic acid ester derivatives; higher fatty acid metal salts such as calcium stearate, zinc stearate, and aluminum stearate; Antioxidants such as amine type and phenol type, benzophenone type,
Various auxiliary agents for pensito can be added. Examples of natural or synthetic inorganic powders include clay and kaolin.

Calcium carbonate, magnesium carbonate, zinc carbonate.

Calcium oxide, magnesium oxide, zinc oxide.

Titanium oxide, aluminum oxide, silicon oxide, magnesium hydroxide, aluminum hydroxide, magnesium silicate, aluminum silicate, white carbon, magnesium aluminosilicate, alumina magnesium hydroxide, and the like are used. Although the method for forming the thermal recording paper of the present invention is not limited to Fi, in general, a leuco dye, a phenol compound sensitizer, and other additives as necessary are mixed in a ball mill, attritor, f -Disperse with a dispersing machine such as a sand mill to form an aqueous dispersion, add a binder, a water-resistant agent, and other additives to the [ ][ to prepare a coating liquid, apply it onto a support using a normal coating machine, and dry it. Paper is usually used most often due to its price, coating suitability, etc. (margins below C).

Examples are shown below to more specifically explain the present invention @Example 1 Stearamide: 201 aqueous dispersion of a 1:1 mixture of stearamide monomethylol 40 parts Sulfonic group content: 2. A heat-sensitive coating liquid was prepared by mixing and stirring 50 parts of a 20% aqueous solution of 0 molar sulfonated polyvinyl alcohol. This was coated on a 50-sheet high-quality paper to a dry coating weight of 6 cm, dried, and then surface-treated using a supercalender to give a smoothness of 500 to 600 seconds to prepare a heat-sensitive recording paper.

Examples 2 to 6 FlK of sulfonated polyvinyl alcohol having a sulfone group content of 2.0 mol in Example 1.

Thermal recording paper was obtained in the same manner as in Example 1 except that sulfonated polyvinyl alcohol having the content of sulfone groups shown in Table 1 was used. Comparative Example 1-10 Polyvinyl alcohol derivative containing sulfone groups in Example 1 A thermosensitive recording paper was obtained in the same manner as in Example 1, except that the water-soluble polymer shown in Table 1 was used instead.

Examples 7 to 10 In Example 1, the content of sulfone group was 2.0 mole [Example 1 except that esterified polyvinyl alcohol was used]
A thermosensitive recording paper was obtained in the same manner as above.

From the evaluation results of the heat-sensitive recording paper obtained in this manner shown in Table 1, it is clear that the present invention can provide a heat-sensitive recording paper with a color density of < quotient, high whiteness, and little background coloring. It is.

Note 1) Color density A: Image density of thermal recording paper that is colored by pressing a heating stamp under the conditions of heating temperature 100°C, contact pressure 2501/j, and heating time 1 second.

B: Image density of a solid black part of an image obtained by conducting an image test using a 9600 baud thermal facsimile machine and using Facsimile Test Chart 2 (Electronic Photography Society) as a manuscript.

Note 2) Whiteness Measured using a Hunter whiteness needle and proof filter.

Note 8) Background coloring ■, Background image density of thermal recording paper left for 48 hours under an environmental condition of 60°C @■, Background image density of thermal recording paper left for 48 hours under an environmental condition of 50°C and 801RHo @Note 4 ) The image density was measured with a Macbeth reflection densitometer RD-514 (using a Wratten #106 filter). Note 5) The larger the value for the color density and whiteness, the better the smaller the value for the background coloration.

Patent applicant: Kojin Co., Ltd.

Claims (1)

[Claims] Colorless maku is a thermosensitive recording material having a coloring layer containing a flame-colored R1co dye and an electron acceptor that causes the dye to develop color when heated, and contains a polyvinyl alcohol derivative containing a sulfone group or a sulfuric acid group as a binder. A heat-sensitive recording medium characterized by: