JPH0414483A - Heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a heat-sensitive recording material with excellent sensing responding properties and high coloring density by a method wherein for a heat- sensitive recording material which contains a normally colorless or light colored dye precursor and an electron receptive compound (developing agent) to make said dye precursor present a color by reacting with the dye precursor at the time of heat- sensing, the heat-sensitive recording material is made to contain specified compounds. CONSTITUTION:The title heat-sensitive recording material contains a compound shown by a general formula. In the formula, E, Y show oxygen or sulfur atom, and they may be the same or different. Z forms an alkylene chain with a carbon number of 2 or more, and it may have a side chain of alkyl group. R<1> shows alkyl group, R<2>, R<3>, R<4> show hydrogen atom, aralkyloxy group and aralkenyloxy group which may have alkoxy group or substituting group. In this case, two out of R<2>, R<3>, R<4> may be combined to form a ring. However all of R<2>, R<3>, R<4> do not become hydrogen atoms at the same time. By using this compound, very small heat energy emitted from a thermal head in an extremely short period of time (normally not more than 1 millisecond) in high speed recording can be utilized for coloring reaction as efficiently as possible, and forming of a colored image of high density becomes possible.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material with excellent thermal responsiveness.

[Conventional technology]

A heat-sensitive recording material generally has a heat-sensitive recording layer on a support, the main components of which are an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting developer. By heating with a laser beam or the like, a dye precursor and a color developer react instantaneously to obtain a recorded image, and are disclosed in Japanese Patent Publication No. 43-4160, Japanese Patent Publication No. 45-14039, etc. These heat-sensitive recording materials have the advantages of being able to record with relatively simple equipment, being easy to maintain, and producing no noise. It is used in a wide range of fields, including ticket vending machines. Particularly in the field of facsimile, the demand for heat-sensitive methods is increasing significantly, and along with this, efforts are being made to increase speed, miniaturize devices, and lower prices in order to reduce transmission costs. As a result, the amount of energy applied for image printing has been steadily decreasing in recent devices. Therefore, there has been a strong demand for the development of highly sensitive heat-sensitive recording materials with high thermal responsiveness that can cope with such higher speed and lower energy facsimiles. In high-speed recording, it is necessary to use the small amount of thermal energy released from the thermal head in an extremely short period of time (usually less than 1 millisecond) for the color reaction to form a high-density color image. be. As a means to achieve the above objective, it is proposed to use a thermofusible substance with a relatively low melting point as a color development accelerator or sensitizer together with a dye precursor and an electron-accepting compound that causes the dye precursor to develop color. has been done. For example, JP-A-57
-64593, JP-A-58-87094 disclose naphthol derivatives, JP-A-57-64592, JP-A-57-185187, JP-A-57-191089,
JP-A-58-110289, JP-A-59-15393
The patent publication discloses naphthoic acid derivatives in JP-A-58-7249.
No. 9 and JP-A-58-87088 propose the use of ether and ester derivatives of phenolic compounds. However, the heat-sensitive recording materials produced using these methods are still insufficient in terms of thermal response, color development sensitivity, etc.

[Purpose of the invention]

An object of the present invention is to obtain a heat-sensitive recording material that has excellent thermal responsiveness and high color development sensitivity.

[Structure of the invention]

In a heat-sensitive recording material containing a normally colorless or light-colored dye precursor and an electron-accepting compound (color developer) that reacts with the dye precursor upon heating to cause the dye precursor to develop color, a compound represented by the following general formula may be included. As a result, a heat-sensitive recording material with excellent thermal responsiveness and high color density could be obtained. General formula (however, in the above formula, X and Y represent oxygen or sulfur atoms,
They may be the same or different. Z forms an alkylene chain having 2 or more carbon atoms, and may have an alkyl group side chain. R1 represents an alkyl group, and R2, R3, and R4 represent a hydrogen atom, an alkoxy group, or an aralkyloxy group or an aralkenyloxy group which may have a substituent. Here, R2, R3, R
Two of 4 may be combined to form a ring. however,
R2, R3R4 do not all become hydrogen atoms at the same time. Specific examples of the compounds of the present invention include those listed below, but the present invention is not limited thereto. (1) 2-Methyl-2-(4-benzyloxyphenyl)-1,3-dioxane 2-methyl-2-(4-benzyloxyphenyl)-1
,3-dithiane2-methyl-2-(4-benzyloxyphenyl)-1
,3-dithiolane 2-ethyl-2-(4-benzyloxyphenyl)-1
,3-dithiane2-ethyl-2-(4-benzyloxyphenyl)-1
,3-dithiolane 2-methyl-2-[4-(4-methylbenzyloxy)
phenyl]-1,3-dioxane 2-methyl-2-[4-(4-methylbenzyloxy)
phenyl]-1,3-dioxolane 2-methyl-2-[4-(4-methylbenzyloxy)
phenyl]-1,3-dithiane2-methyl-2-[4-(4-methylbenzyloxy)
phenyl]-1,3-dithiolane (10) 2,4.54limethyl-2-[4(4-methylbenzyloxy)phenyl]-1,3-dithiolane (11) 2-ethyl-2-[4-( 4-methylbenzyloxy)phenyl]-1,3-dithiane (12) 2-ethyl-2-[4-(4-methylbenzyloxy)phenyl]-1,3-dithiolane (13) 2-ethyl-2- [4-(4-methylbenzyloxy)phenyl]-1,3-oxathiolane(14)2-methyl-2-[4-(3-methylbenzyloxy)phenyl]-1,3-dithiane(15)2- Methyl-2-[4-(2-methylbenzyloxy)phenyl]-1,3-dithiane (16) 2-ethyl-2-[4-(4-methylbenzyloxy)phenyl]-1,3-dithiane ( 17) 2-Methyl-2-[4-(4-chlorobenzyloxy)phenyl]-1,3-dioxane (18) 2-methyl-2-[4-(4-chlorobenzyloxy)phenyl2 1.3 -Dioxolane (19) 2-methyl-2-[4-(4-chlorobenzyloxy)phenyl]-1,3-dithiane (20) 2-methyl-2-[4-(4-chlorobenzyloxy)phenyl] -1,3-dithiolane (21) 2-methyl-2-[4-(4-methoxybenzyloxy)phenyl]-1,3 dioxane (22) 2-methyl-2-[4-(4-methoxybenzyloxy) ) phenyl]-1,3-dithiane (23) 2-methyl-2-[4-(4-methoxybenzyloxy)phenyl]-1,3-dithiolane (24) 2-methyl-2-[3-(4 -methylbenzyloxy)phenyl-1,3-dithiane (25) 2-methyl-2-[3-(4-methylbenzyloxy)phenyl]-1,3-dithiolane (26) 2-methyl-2-[2 -(4-methylbenzyloxy)phenyl]-1,3-dithiane(27)2-methyl-2-[2-(4-methylbenzyloxy)phenyl]-1,3-dithiolane(28)2-methyl- 2-(3-methoxy-4-benzyloxyphenyl)-1,3-dithiane(29)2-methyl-2-(4-methoxyphenyl)-
1,3-dithiane (30) 2-methyl-2-(2,4-dimethoxyphenyl)-1,3-dithiane (31) 2-methyl-2-(3,4-dimethoxyphenyl)-1,3- Dithian(32)2-methyl-2-(3,4,54rimethoxyphenyl)-1,3-dithiane(33)2-methyl-2-(2,4-dibenzyloxy)phenyl]-1, 3-dithiane (34) 2-methyl-
2-(4-Phenethyloxyphenyl)-1,3-dithiane (35) 2-methyl-2-[4-(3-phenylpropoxy)phenyl]-1,3-dithiane (36) 2-methyl-2- [4-(3-phenylpropoxy)phenyl]-1,3-dithiolane (37) 2-methyl-2-(4-cinnamyloxyphenyl)-1,3-dioxane (38) 2-methyl-2-( 4-cinnamyloxyphenyl)-1,3-dioxolane (39) 2-methyl-2-(4-cinnamyloxydiphenyl)-1,3-dithiane (40) 2-methyl-2-(4-cinnamyl oxyphenyl)-1,3-dithiolane (41) 2-ethyl-2-(4-cinnamyloxyphenyl)-1,3-dithiane (42) 2-ethyl-2-(4-cinnamyloxyphenyl)- 1,3-dithiolane (43) 2-methyl-2-(3,4-methylenedioxyphenyl))-1,3-dithiane The compound of the present invention can be easily synthesized by known methods. For example, aromatic ketones such as acetophenone are reacted with diols such as propanediol or dithiols such as ethanedithiol, usually using an acid catalyst, to obtain cyclic acetals or cyclic dithioacetals under mild conditions and in high yields. be able to. In this case, the reaction with the diol is usually carried out while removing water. Here, specific synthesis examples of the compound represented by the above general formula are shown, but the present invention is not limited thereto. Synthesis example 1 2-methyl-2-(4-benzyloxyphenyl)-1
, 3-dithiane (compound 2) Weigh out 27.2 g of 4-hydroxyacetophenone and add 100 m of DMF.
1, 25.3 g of benzyl chloride, and 30.4 g of potassium carbonate were added, and the mixture was stirred at 100 to 110° C. for 3 hours under a nitrogen stream. After cooling, pour into approximately 21 g of ice water and collect the precipitated solid by filtration.
It was washed with water until it became neutral. After drying, 500m ethanol
1 to obtain 38.8 g of 4-benzyloxyacetophenone. Melting point: 92°5-93°C. Subsequently, 11.3 g of 4-benzyloxyacetophenone
Weigh out and add 100 ml of ethanol 1,1°3-propanedithiol5. Oml and 1.5 g of boron trifluoride etherate were added, and the mixture was refluxed for 5 hours. When left to cool, crystals precipitate. The crystals were collected by filtration, washed with ethanol, and then recrystallized from 400 ml of ethanol to obtain 12.6 g of the desired product. Melting point: 121-121.5°C. Synthesis example 2 2-methyl-2-(4-benzyloxyphenyl)-
Synthesis of 1,3-dithiolane (Compound 3) 11.3 g of 4-benzyloxyacetophenone obtained in Synthesis Example 1 was weighed out, and 100 ml of ethanol was added. ．． 4.2 ml of 2-ethanedithiol and boron trifluoride etherate 1,5
g was added thereto, and the mixture was refluxed for 5 hours. When left to cool, crystals precipitate. After filtering the crystals and washing them with ethanol, add 20% ethanol.
Recrystallization was performed from 0 ml to obtain 10.4 g of the target product. Melting point: 70.5-71°C. Synthesis example 3 2-ethyl-2-(4-benzyloxyphenyl)-1
, 3-dithiane (Compound 4) In the same manner as in Synthesis Example 1, 19.8 g of 4-benzyloxypropiophenone was obtained from 15.0 g of 4-hydroxypropiophenone and 17.1 g of benzyl chloride. Melting point 101.5
~102℃. Subsequently, 9.6 g of 4-benzyloxypropiophenone
and propanedithiol4. 10.1 g of the target product was obtained from Oml. Melting point: 101.5-102°C. Synthesis example 4 2-ethyl-2-(4-benzyloxyphenyl)-1
, 3-Dithiolane (Compound 5) 9.6 g of 4-benzyloxypropiophenone obtained in Synthesis Example 3 and 3.4 m of 1°2-ethanedithiol in the same manner as in Synthesis Example 2.
8.2 g of the target product was obtained from 1. Melting point 52-53°C. Synthesis example 5 2-methyl-2-[4-(4-methylbenzyloxy)
Synthesis of phenyl]-1,3-dithiolane (compound 9) In the same manner as in Synthesis Example 1, 27.2 g of 4-hydroxyacetophenone and 28.2 g of 4-methylbenzyl chloride were added.
1g to 43.3g of 4-(4methylbenzyloxy)
Acetophenone was obtained. Melting point: 104-104.5°C. Subsequently, in the same manner as in Synthesis Example 2, 27.4 g of the target product was obtained from 30 g of 4-(4-methylbenzyloxy)acetophenone and 10.5 ml of 1,2-ethanedithiol. Melting point: 91.5-92.5°C. Synthesis example 6 2-methyl-2-[4-(4-chlorobenzyloxy)
Synthesis of phenyl]-1,3-dithiolane (compound 20) In the same manner as in Synthesis Example 1, 16.3 g of 4-hydroxyacetophenone and 19.
28.2 g of 4-(4-chlorobenzyloxy)acetophenone was obtained from 3 g. Melting point: 141.5-142.5°C. Subsequently, in the same manner as in Synthesis Example 2, 13.0 g of 4-(4-chlorobenzyloxy)acetophenone and 1,2-
11.7 g of the target product was obtained from 4.2 ml of ethanedithiol. Melting point: 94-94.5°C. Synthesis Example 7 Synthesis of 2-methyl-2-(3,4-methylenedioxyphenyl)-1,3-dithiane (Compound 43) 6.6 g of 3,4-methylenedioxyacetophenone was prepared in the same manner as in Synthesis Example 1. and propanedithiol 4.0m
5.3 g of the target product was obtained from 1. Melting point 77-78°C. Next, a specific method for producing the heat-sensitive recording material according to the present invention will be described. The heat-sensitive recording material according to the present invention generally has an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting compound as main components on a support, and these are dispersed and coated in a binder to form a heat-sensitive recording layer. By heating with a thermal head, thermal pen, laser beam, etc., a dye precursor and an electron-accepting compound react instantaneously to obtain a recorded image.
It is disclosed in Japanese Patent Publication No. 3-4160, Japanese Patent Publication No. 45-14039, etc. Further, pigments, sensitizers, antioxidants, anti-sticking agents and the like are added to the heat-sensitive recording layer as necessary. The dye precursor used in the heat-sensitive recording material according to the present invention is not particularly limited as long as it is generally used in pressure-sensitive recording paper or heat-sensitive recording paper. Specific examples include (1) triarylmethane compounds 3.3-bis(p-dimethylaminophenyl) = 6-dimethylaminophthalide (crystal violet lactone), 3.3-bis(p-dimethylamino phenyl)phthalide, 3-(p-dimethylaminophenyl)-3-
(1,2-dimethylindol-3-yl)phthalide,
3-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-phenylindole-
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-bis(2-phenylindole-
3-yl)-5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-(1-methylpyrrole-2
-yl)-6-dimethylaminophthalide, etc., (2) diphenylmethane compounds 4.4゛-bis(dimethylaminophenyl)benzhydrylbenzyl ether, N-chlorophenylleucoauramine, N-2,4,5- 4-lichlorophenylleucoolamine, etc., (3) Xanthine compounds Rhodamine B anilinolactam, Rhodamine B-p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octyl Aminofluorane, 3-diethylamino-7-phenylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7-(3,4-dichloroaniline) Lino) fluorane, 3-diethylamino-7-
(2-chloroanilino)fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-tolyl)amino-6-methyl-7-anilinofluorane, 3-piperidino-6 -Methyl-7-anilinofluorane, 3-(N-ethyl-N-tolyl)amino-6-methyl-7-funinethylfluorane, 3-diethylamino-7-(4-nitroanilino)fluorane, 3
-dibutylamino-6-methyl-7-anilinofluorane, 3-(N-methyl-N-propyl)amino-6-methyl-7-anilinofluorane, 3-(N-ethyl-N
-isoamyl)amino-6-methyl-7-anilinofluorane, 3-(N-methyl-N-cyclohexyl)amino-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-tetrahydrofuryl) )amino-6-methyl-
7-anilinofluorane, etc., (4) Thiazine compounds benzoylleucomethylene blue, p-nitrobenzoylleucomethylene blue, etc., (5) Spiro compounds 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3. 3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho-(3-methoxybenzo)spiropyran, 3-
Propyl spirobenzopyran and the like can be mentioned, and these can be used alone or in combination of two or more. The color developer is not particularly limited as long as it is an acidic substance commonly used in thermal paper. For example, polyvalent metal salts such as phenol derivatives, aromatic carboxylic acid derivatives, N, N'diarylthiourea derivatives, and zinc salts of organic compounds can be used. Particularly preferred are phenol derivatives, such as p-phenylphenol, p-hydroxyacetophenone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, and 4-hydroxy-4'-isopropoxydiphenylsulfone. Hydroxy-4°
-benzenesulfonyloxydiphenylsulfone, 1.
1-bis(p-hydroxyphenyl)propane, 1.1
-bis(p-hydroxyphenyl)pentane, 1.1-
Bis(p-hydroxyphenyl)hexane, 1,1-bis(p-hydroxyphenyl)cyclohexane, 2,2
-bis(p-hydroxyphenyl)propane, 2,2bis(p-hydroxyphenyl)hexane, 1゜1-bis(p-hydroxyphenyl)-2-ethylhexane, 2
．． 2-bis(3-chloro-4-hydroxyphenyl)propane, 1,1-bis(p-hydroxyphenyl)-1-
Phenylethane, 1,3-di[2-(p~hydroxyphenyl)2-propyl]benzene, 1,3-di[2
(3,4-dihydroxyphenyl)-2-propyl]benzene, 1,4-di[2-(p-hydroxyphenyl)-2-propyl]benzene, 4°4°-dihydroxydiphenyl ether, 4,4'-dihydroxy Diphenylsulfone, 3,3°dichloro-4,4°-dihydroxydiphenylsulfone, 3,3°-diallyl-4,4
° -dihydroxydiphenylsulfone, 3,3° -
Dichloro-4,4'-dihydroxydiphenyl sulfide, 2,2-bis(4-hydroxyphenyl)methyl acetate, 2,2-bis(4-hydroxyphenyl)butyl acetate, 4,4°-thiobis(2-1- Butyl-5-
methylphenol), benzyl p-hydroxybenzoate, chlorobenzyl p-hydroxybenzoate, dimethyl 4-hydroxyphthalate, benzyl gallate, stearyl gallate, salicylanilide, 5-chlorosalicylanilide, and the like. Binders used in heat-sensitive recording materials include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein,
Alkali salts of polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer , water-soluble adhesives such as alkali salts of ethylene/maleic anhydride copolymers, polyvinyl acetate, polyurethane, polyacrylic esters, styrene/butadiene copolymers, acrylonitrile/butadiene copolymers, methyl acrylate/butadiene copolymers Examples include polymers and latexes such as ethylene/acetic acid copolymer. In addition, N-
Waxes such as hydroxymethylstearamide, stearamide and palmitic acid amide, naphthol derivatives such as 2-benzyloxynaphthalene, biphenyl derivatives such as p-benzylbiphenyl and 4-allyloxybiphenyl, 1,2-bis(3 -methylphenoxy)
Polyether compounds such as ethane, 2.2'-bis(4-methoxyphenoxy) diethyl ether, bis(4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate, bis(p-methylbenzyl) oxalate ester Carbonic acid or oxalic acid diester derivatives such as these can be added in combination. Examples of the pigment include diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin, and the like. In addition, higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearic acid amide, and castor wax are used to prevent head wear and stickiness, as well as dioctyl sulfosuccinate. Dispersants such as sodium chloride, ultraviolet absorbers such as benzophenone and benzotriazole, and surfactants, fluorescent dyes, and the like are added as necessary. As the support used in the present invention, paper is mainly used, but nonwoven fabric, plastic film, synthetic paper, metal foil, etc., or a composite sheet of a combination of these can also be used as desired. In addition, in the production of heat-sensitive recording materials, an overcoat layer is provided to protect the heat-sensitive recording layer, and an undercoat layer consisting of a single layer or multiple layers of pigment or resin is provided between the heat-sensitive recording layer and the support. Various known techniques can be used. The amount of coating on the heat-sensitive recording layer is determined by the amount of dye precursor and color developer, which are color forming components, and is usually 0.1 to 1.0 g.
/rrf is appropriate. Further, the amount of the color developer added is 5 to 400% by weight based on the dye precursor, and a particularly preferable addition amount is 20 to 300% by weight. The compound of the present invention is added in an amount of 5 to 400% by weight based on the color developer, and a particularly preferable addition amount is 20 to 300% by weight.

【Example】

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight. Preparation of heat-sensitive recording material (1) Preparation of heat-sensitive coating liquid Dye precursor 3-dibutylamino-6-methyl-7
- 35 parts of anilinofluorane and 80 parts of a 2.5% polyvinyl alcohol aqueous solution were ground in a ball mill for 24 hours to obtain a dye dispersion. Next, 40 parts of 2.2-bis(p-hydroxyphenyl)propane was ground with 60 parts of a 2.5% polyvinyl alcohol aqueous solution in a ball mill for 24 hours to obtain a color developer dispersion. 2-Methyl-2-(4-benzyloxyphenyl)-1,3-dithiane (compound 2)
50 parts were ground together with 120 parts of a 2.5% polyvinyl alcohol aqueous solution in a ball mill for 24 hours to obtain a dispersion of the compound of the present invention. After mixing the above three types of dispersions, the following were added under stirring to prepare a heat-sensitive coating liquid. Calcium carbonate 50% dispersion 100 parts Zinc stearate 40% dispersion 25 parts 10 % polyvinyl alcohol aqueous solution 185 parts water
280 copies (2) Preparation of heat-sensitive coated paper A coating liquid consisting of the following composition is smeared on base paper with a basis weight of 40 g/rrf to a solid content of 9 g/nf, and dried to create heat-sensitive coated paper. did. Calcined kaolin 100 parts Styrene-butadiene latex 50% aqueous dispersion 24 parts water
200 copies (3) Preparation of heat-sensitive recording material The heat-sensitive coating liquid prepared in (1) was smeared on the surface of the heat-sensitive coating paper prepared in (2) at a solid content coating amount of 4 g/rrf, and dried. A heat-sensitive recording material was prepared. Examples 2 to 7 2-methyl-2-(4-benzyloxyphenyl)-1,3-dithiolane in place of 2-methyl-2-(4-benzyloxyphenyl)-1,3-dithiane in Example 1 (Example 2: Compound 3), 2-ethyl-2-(4
-benzyloxyphenyl)-1,3-dithiane (Example 3: Compound 4), 2-ethyl-2-(4-benzyloxyphenyl)-1,3-dithiolane (Example 4: Compound 5), 2- Methyl-2-[4-(4-methylbenzyloxy)phenyl]-1,3-dithiolane (Example 5:
Compound 8), 2-methyl-2-[4(4-chlorobenzyloxy)phenyl]-1°3-dithiolane (Example 6)
: Compound 18), 2methyl-2-(3,4-methylenedioxyphenyl)-1,3-dithiane (Example 7: Compound 40) was used to prepare a heat-sensitive recording material in the same manner as in Example 1. Created. Comparative Example 1 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that 2-methyl-2-(4-benzyloxyphenyl)-1,3-dithiane in Example 1 was removed. Comparative Example 2 A heat-sensitive recording material was prepared in the same manner as in Example except that N-hydroxymethylstearamide was used instead of 2-methyl-2-(4-benzyloxyphenyl)-1,3-dithiane in Example 1. It was created. The heat-sensitive recording materials obtained in Evaluation Examples 1 to 7 and Comparative Example 1.2 were calendered so that the Bekk smoothness of the heat-sensitive coated surface was 400 to 500 seconds, and then subjected to a facsimile tester TH- manufactured by Taishiki Denki. A printing test was conducted using PMD. A thermal head with a dot density of 8 dots/shape and a head resistance of 185 Ω was used, with a head voltage of 12 mm and a pulse width of 0.5.
Then, electricity was applied for 0.7 milliseconds to print, and the color density was measured using a Macbeth RD-918 model reflection densitometer. The results are shown in Table 1 below.
Shown below. Table 1

【Effect of the invention】

As is clear from the examples, by containing the compound of the present invention, it was possible to obtain a heat-sensitive recording material with excellent thermal responsiveness, high optical density with the same applied energy, and high color development sensitivity. 1) Specification, page 28, line 3 [Compound 40゜1, case description 2, title of the invention 3, name of address related to the case of the person making the amendment 1990 Patent Application Thermal Recording Material No. 118242

Claims (1)

[Claims] 1. A heat-sensitive recording material containing a normally colorless or light-colored dye precursor and an electron-accepting compound that reacts with the dye precursor when heated to cause the dye precursor to develop a color, in which a compound represented by the following general formula is used. A heat-sensitive recording material characterized by containing: General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, in the above formula, X and Y represent oxygen or sulfur atoms,
They may be the same or different. Z forms an alkylene chain having 2 or more carbon atoms, and may have an alkyl group side chain. R^1 represents an alkyl group, and R^2, R^3, and R^4 represent a hydrogen atom, an alkoxy group, or an aralkyloxy group or an aralkenyloxy group which may have a substituent. Here, R^2
, R^3, and R^4 may be combined to form a ring. However, R^2, R^3, and R^4 do not all become hydrogen atoms at the same time.