JPH04191087A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having no problem from the aspect of toxity and excellent in the storage stability of a background part and a color forming part by adding 4-benzyloxy-4'-(2-methylglycydyloxy) diphenylsulfone or 4-(4-methylbenzyloxy)-4'-glycydyloxydiphenylsulfone to an overcoat layer. CONSTITUTION:A thermal recording material is obtained by providing a thermal recording layer containing a leuco dye and a developer allowing the leuco dye to form a color on a support and further providing an overcoat layer thereon. 4-benyloxy-4'-(2-methylglycydyloxy)diphenylsulfone or 4-(4- methylbenzyloxy)-4'-glycydyloxydiphenylsulfone is added to the overcoat layer. This thermal recording material is extremely excellent in the stability of a background part and a color forming part and also advantageous industrially because the epoxy compound to be used has no problem from the aspect of toxity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a heat-sensitive recording material containing a novel epoxy compound in an overcoat layer and having excellent storage stability in the background area and colored area.

[Conventional technology]

Thermosensitive recording materials that utilize color development due to the reaction between leuco dyes and color developers are widely used as thermosensitive recording paper for recording output from facsimiles, printers, and the like.

As for the characteristics of a heat-sensitive recording material, it is desired that the color development sensitivity be high, the background whitening be high, and the storage stability of the colored image and the background be high. Various epoxy compounds are known as substances added to the recording layer or overcoat layer in order to improve the storage stability of heat-sensitive recording materials, but their stabilizing effects are not sufficient, and epoxy compounds However, it is not preferred due to the toxicity problems that are commonly associated with.

[Invention or problem to be solved]

An object of the present invention is to provide a heat-sensitive recording material that uses a novel epoxy compound that does not have the above-mentioned toxicity problems and has excellent storage stability in the background and colored areas.

[Means to solve the problem]

The present invention provides a heat-sensitive recording material in which a heat-sensitive recording layer containing a leuco dye and a color developer for coloring the leuco dye is provided on a support, and an overcoat layer is provided on the heat-sensitive recording layer. 4-pencyloxy-4'-(
2-Methylglycidyloxy)diphenylsulfone (abbreviated as compound A) or 4-(4-methylhensyloxy)=4°-glycycyloquine diphenylsulfone (abbreviated as compound B) It is something.

The heat-sensitive recording material of the present invention has extremely excellent storage stability in the background and colored areas, and the epoxy compound used in the present invention is a substance that poses no toxicity problems, unlike ordinary epoxy compounds. Therefore, it is advantageous in industrial implementation.

The epoxy compound used in the present invention can be produced by a conventional reaction between phenols and epichlorohydrin, that is, according to the following reaction formula.

(In the above reaction formula, Bz represents a pencil group or a 4-methylbenzyl group, and R represents a hydrogen atom or a methyl group.) Leuco dyes used in the heat-sensitive recording material of the present invention include fluoran, phthalide, and lactam dyes. It is a color-forming dye that develops color when it comes into contact with an acidic color developer, including but not limited to leuco dyes such as leuco dyes, triphenylmethane-based, phenothiane-based, and spiropyran-based dyes. You can use it if you have it. These dyes include, for example, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalite, 3-diethylamino-5-methyl-7-methylaminofluoran, 3-diethylamino -7-dibensylaminofluorane, 3-(N-ethyl-N-isobutylamino)-7-anilinofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-(N-ethyl- N-isobutylamino)-6-methyl-7-chlorofluorane, 3-C4-(N,N-dibutylamino)phenylcoamino-6-methyl-7-chlorofluorane, 3-C4-(
4-(phenylamino)phenylamino) Phenylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilino Fluoran, 3-(N-ethyl-N-isobutylamino)-〇-methyl-7-anilitofluoran, 3-(N-methyl-N-propylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-
7-Chloroanilinofluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, 3-diethylamino-7-bennylaminofluoran, 3-diethylamino-5-methyl-7-bensylaminofluoran , 3-(N-ethyl-ph-ruinno)-6-methyl-7
~anilinofluorane 3-(N-chlorohequine-N-methylamino)-6-
Methyl-7-anilinofluorane, 3-pyrrolidino-6
Examples include, but are not limited to, -methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, and the like.

Furthermore, as the color developer, any acidic substance that can be used as a color developer in heat-sensitive recording materials can be used, such as bisphenol A, 4,4°-5eC-butylidene bisphenol, 4,4° -chlorohexylidene bisphenol, 2,2-(4-hydroquinphenyl)-4-methylpentane,],]3-bis1-(4-hydroxyphenyl)-1-methylethyl]benzene, 1,4- BisC1(4-hydroxyphenyl)-1-methylethyl]
Hensen, 2.2°-dihydroxydiphenyl, bisphenol compounds such as pentamethylene-bis(4-hydroxybenzoate), sulfur-containing hissyl compounds such as 1,7-cy(4-hydroxyphenylthio)-3,5-dioxahebutane, etc. Phenol compound, Hensyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroquine benzoate, isopropyl 4-hydroxybenzoate,
4-hydroxybenzoic acid esters such as butyl 4-hydroquine benzoate, isobutyl 4-hydroquine benzoate, chlorohensyl 4-hydroxybenzoate, methyl hensyl 4-hydroxybenzoate, diphenylmethyl 4-hydroxybenzoate, zinc benzoate, 4-hydroxybenzoic acid esters, etc. - Benzoic acid metal salts such as zinc nitrobenzoate, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-isopropoquine diphenylsulfone, 4-hydroxy-4'
-Hydroxysulfones such as butoxine phenylsulfone, 4-hydroquinphthalic acid diesters such as dimethyl 4-hydroxyphthalate, cycyclohequinyl 4-hydroxyphthalate, diphenyl 4-hydroxyphthalate, 2
- Esters of hydroquine naphthoic acid such as hydroxy-6-carboquine naphthalene, hydroxyacetophenone, p-phenylphenol, 4-hydroxyphenylacetic acid, p-hensylphenol, hydroquinone monohensyl ether, and tribromomethylphenyl Examples include tribromomethylsulfones such as sulfone.

The mixing ratio of the dye and color developer can be changed as appropriate depending on the type of dye, and is usually 1 to 10 parts by weight, preferably 2 to 5 parts by weight, of the color developer to 1 part by weight of the dye. Department.

The heat-sensitive recording material of the present invention can be manufactured according to a conventional method. For example, a recording layer coating liquid, which is an aqueous dispersion of a dye, a color developer, and a binder, is applied to paper, plastic film, synthetic paper, etc. After forming a recording layer by coating and drying on a support such as the above, an overcoat layer coating solution containing the epoxy compound of the present invention and a binder may be coated and dried on the recording layer.

The amount of the epoxy compound of the present invention added to the overcoat layer is 0.65% by weight or more, preferably 1 to 70% by weight.

The epoxy compound of the present invention can also be added to the recording layer to further improve storage stability.

The binder may be one that can be generally used in heat-sensitive recording materials, such as starches, hydroquine ethylcellulose, methylcellulose, calhoquine methylcellulose, seratin, casein, arahyacum,
Polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol,
Diisobutylene/maleic anhydride copolymer salt, styrene/maleic anhydride copolymer salt, ethylene/acrylic acid copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulsion, urea resin, Examples include melamine resin and amide resin.

A sensitizer may be appropriately added to the recording layer coating liquid depending on the purpose. Examples of the sensitizer include higher fatty acid amide, henzamide, stearanilide, acetoacetanilide, thioacetanilide, sulfuric acid, methyl phthalate, terephthalic acid, methyl isophthalate, bis(ter(-butylphenol)), 4゜4゛-7 ethers of cihytroquine phenylsulfone, 1,2-his(phenoquine)ethane, 1
゜2-his(4-methylphenoquine)ethane, 1゜2-
his(3-methylphenoquino)ethane, 2-naphtholhensyl ether, nphenylamine, carbazole,
Examples include 2,3-cy-m-tolylbutane, 4-henzylhyphenyl, 4,4°-dimethylbiphenyl, m-terphenyl, di-β-naphthylphenylenediamine, and the like. Further, depending on the purpose, various auxiliary agents such as fillers, dispersants, antioxidants, desensitizers, anti-blocking agents, antifoaming agents, light stabilizers, and optical brighteners can be appropriately incorporated.

The overcoat layer coating liquid contains the Epoquine compound of the present invention,
It is an aqueous dispersion containing the above-mentioned binder and, if necessary, auxiliary additive components such as fillers and lubricants. Examples of fillers include calcium carbonate, silica, zinc oxide, barium sulfate, clay, talc, etc., and examples of lubricants include higher fatty acids or their esters, amides or metal salts, and various waxes.

Further, an undercoat layer may be provided between the support and the recording layer by a conventional method.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Synthesis of 4-benzyloxy-4'-(2-methylbenzyloxy)diphenylsulfone (Compound A) 34 g of 4-hensyloxy-4'-hydroxydiphenylsulfone, 43 g of 2-methylepichlorohydrin, and tetrabutylammonium chloride as a catalyst 1g
was added and reacted at 70 to 758C for 10 hours. After the reaction, epichlorohydrin was distilled off under reduced pressure. Furthermore, 50 ml of toluene was added and distilled off under reduced pressure to remove epichlorohydrin.

250 ml of toluene was added to this reaction mixture, and under reflux,
A 50% aqueous solution of caustic soda IO- was slowly added dropwise, and the mixture was allowed to react after azeotropic dehydration. After completion of the dehydration, the mixture was filtered hot and the filtrate was cooled to obtain 35 g of white crystals of the target compound.

(Melting point 163.0-166.0°C) Example 2 Synthesis of 4-(4-methylbenzyloxy)-4'-')phosphorusyloxydiphenylsulfone [Compound B] 4-(4-methylbenzyloxy) -4゛-Hydroxydiphenylsulfone 17.7 g (0.05 mol),
46.3 g (0.5 mol) of epichlorohydrin and 0.8 g of tetrabutylammonium chloride as a catalyst were placed in a 4-diameter flask and reacted at 100 to 120° C. for 8 hours. After the reaction, excess epichlorohydrin in the reaction solution was distilled off under reduced pressure, and 150% of toluene was added and the temperature was raised.
2 g of caustic soda was added thereto, and the mixture was reacted at 100°C for 2 hours. After the reaction, the tolunin solution was washed with water and filtered, and the precipitated crystals were filtered and dried to obtain 13.3 g of white crystals of the target compound.

(Melting point: 125.8-127.2°C) In the following, all "parts" shown in the description of the method for producing a heat-sensitive recording paper or in the examples represent "parts by weight."

Example 3 (Preparation of dispersion) (Liquid A) Dye dispersion 2-anilino-3-methyl-6-sibutylaminofluorane 6 parts Polyvinyl alcohol 15 parts aqueous solution 40 parts Clay
14 parts pure water
40 parts (Liquid B) Color developer dispersion Bisphenol A 9 parts Polyvinyl alcohol 15% aqueous solution 40 parts Clay
11 parts pure water
40 parts (Liquid C) Overcoat layer coating solution 15% polyvinyl alcohol aqueous solution 20 parts Compound A
4 parts calcium carbonate
3 parts 30% zinc stearate dispersion 3 parts pure water
Each dispersion liquid was prepared by sufficiently grinding 70 parts of the mixture having the above composition using a sand grinder.

Example 4 A coating solution prepared by mixing 1 part of solution A and 2 parts of solution B was coated and dried on white paper using a wire rod Nα12. Furthermore, add liquid C on top of it at a solid content of approximately 2 g/
It was coated and dried to obtain heat-sensitive recording paper.

Example 5 A thermosensitive recording paper was produced in the same manner as in Example 4 except that Compound B was used in place of Compound A in Liquid C.

Example 6 A thermosensitive recording paper was produced in the same manner as in Example 4 except that 4-isopropoquine-4°-hydroxydiphenylsulfone was used in place of bisphenol A in Liquid B.

Example 7 Performed using 2-anilino-3-methyl-6-(N-methyl-N-cyclohexylamino)fluorane in place of 2-anilino-3-methyl-6=dibutylaminofluorane in Solution A. A thermosensitive recording paper was produced in the same manner as in Example 4.

Comparative Example 1 A thermosensitive recording paper was produced in the same manner as in Example 4 except that calcium carbonate was used in place of Compound A in Liquid C.

Test Example 1 The thermal recording papers produced in Examples 4 to 7 and Comparative Examples were saturated and colored in a zigzag pattern using a thermal paper coloring tester, and with a vinyl chloride wrap film in close contact with both sides, 1
The plasticizer resistance test was conducted by leaving the sample in a dark place at about 256C (room temperature) for 0 days. As a result of observing changes in color density before and after the test, the thermosensitive recording paper of the present invention had extremely excellent plasticizer resistance as shown in Table 1 below.

◎, Very slightly discolored ○ Slightly discolored △ Significantly discolored × Almost discolored [Effects of the invention] The thermal recording paper made of the compound of the present invention has high storage stability of the background, and the fastness of colored images, especially It has excellent plasticizer resistance.

Applicant (430) Nippon Soda Co., Ltd. Agent (7125) Yoshimi Kaade (9648) Yusaku Tokai

Claims (1)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive recording layer containing a leuco dye and a color developer for coloring the leuco dye is provided on a support, and an overcoat layer is provided thereon, the overcoat layer contains 4-benzyloxy-4'-(2-methylglycidyloxy)diphenylsulfone or 4-(
A heat-sensitive recording material characterized by containing 4-methylbenzyloxy)-4'-glycidyloxydiphenylsulfone.