JPH03234580A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enable a highly heat-sensitive, highly coloring-sensitive thermal recording material by adding a specific compound to a thermal recording material which contains a normally colorless or pale dye precursor and an electron- receptive compound (developer) which causes the dye precursor to develop color through chemical reaction when heated. CONSTITUTION:A compound shown by the Formula I is added to a thermal recording material which contains a normally colorless or pale dye precursor and an electron-receptive compound which causes the dye precursor to develop color through reaction when heated. In the Formula I, X, Y are oxygen or sulfur atom, and Z forms an alkylene chain having more than 2C and may have a side chain of the alkyl group. In addition, R<1>, R<2>, R<3> are a hydrogen atom, an alkoxy group, an alkylthio group or an aralkyloxy group which may have a substitution group. Thus it is possible to obtain a thermal recording material capable of high optical intensity using the same processing energy and also high coloring sensitivity.

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.

<Prior art> Heat-sensitive recording materials generally have 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 color developer. By heating with a thermal pen, laser light, etc., 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. has been done. 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 possible to use a thermofusible substance with a relatively low excitation 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. Proposed. For example, JP-A-57
-64593, JP-A-58-87094 disclose naphthol derivatives; Naphthoic acid derivatives are disclosed in Japanese Patent Application Laid-open No. 58-72499.
No. 58-87088 proposes 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.

<Objective of the Invention> An object of the present invention is to obtain a heat-sensitive recording material having excellent thermal responsiveness and high color development sensitivity.

<Structure of the Invention> 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 a color, which is represented by the following general formula. By incorporating the compound, it was possible to obtain a heat-sensitive recording material with excellent thermal responsiveness and high color density.

General formula (however, in the above formula, X and Y represent oxygen or sulfur atoms,
They may be the same or different.

Further, 2 forms an alkylene chain having 2 or more carbon atoms, and may have an alkyl group side chain.

Further, R1, R2, and R3 represent a hydrogen atom, an alkoxy group, an alkylthio group, or an aralkyloxy group which may have a substituent. However, RI SR2, R3
Not all of R become hydrogen atoms at the same time, and R
When two of 1, R2, and R3 are hydrogen atoms and the remaining one is an aralkyloxy group, the aralkyloxy group is not in the para position. ) Specific examples of the compounds of the present invention include those listed below, but the present invention is not limited thereto.

(1) 2-(4-methoxyphenyl)-1,3-dioxane 2-(4-methoxyphenyl)-1,3-dithiane 2-(3-methoxyphenyl)-1,3-dithiane 2-(2- methoxyphenyl)-1,3-dioxane 2-(2-methoxyphenyl)-1,3-dithiane 2-(4-ethoxyphenyl)-1,3-dithiane 2-(2-ethoxyphenyl)-1, 3-dithiane 2-(2,4-dimethoxyphenyl)-1,3-dithiane 2-(2,4-dimethoxyphenyl)-1,3-dithiolane (10) 2-(2,5-dimethoxyphenyl)-1 ，
3-dithiane (2) (3) (4) (5) (6) (7) (8) (9) (11) 2- (2,6-dimethoxyphenyl)-1,
3-dithiane 2-(3,4-dimethoxyphenyl)-1,3-dithiane 2-(3,4-dimethoxyphenyl)-1,3-dithiolane 2-(3,5-dimethoxyphenyl)-1,3- Dithiane 2- (2,4,64rimethoxyphenyl)-1,3-
Dithiane 2-(3,4,5-trimethoxyphenyl)-1,3
-dithiane 2-(3-methoxy-4-ethoxyphenyl)-1,3
-Dioxane (18) 2- (3-methoxy-4-ethoxyphenyl)-1,3-dioxolane 2-(3-methoxy-4-ethoxyphenyl)-1,3
-dithiane 2-(3-ethoxy-4-methoxyphenyl)-1,3
-dithiane (20) (17) (19) (16) (15) (13) (12) (14) (21)2- (3,4-jethoxyphenyl)-1,
3-dithiane (22) 2- (3-benzyloxyphenyl) 1.3
-dithiane (23) 2- (2-benzyloxyphenyl) 1.3
-dithiane(24)2-[3-(4-methylbenzyloxy)phenyl]-1,3-dioxane(25)2-[3-(4-methylbenzyloxy)phenyl]-1,3-dithiane(26 )2-[3-(4-methylbenzyloxy)phenyl]-1,3-dithiolane (27)2-[3-(4-methoxybenzyloxy)
phenyl]-1,3-dithiane(28)2-[3-(4-chlorobenzyloxy)phenyl-1,3-dithiane(29)2-[3-(3,4-dimethylbenzyloxy)phenyl]- 1,3-dithiane(30)2-[2
-(4-methylbenzyloxy)phenylco 1,3-
Dithiane 2-[2-(4-chlorobenzyloxy)phenyl]
-1,3-dithiane 2- [2-(4-methoxybenzyloxy)phenyl]-1,3-dithiane 2-(3-methoxy-4-benzyloxyphenyl)-
1,3-dioxane 2-(3-methoxy-4-benzyloxyphenyl)-
1,3-dioxolane 2-(3-methoxy-4-benzyloxyphenyl)-
1,3-dithiane(36)2-(3-methoxy-4-benzyloxyphenyl)-1,3-dithiolane 2-(3-ethoxy-4-benzyloxyphenyl)-
1,3-dithiane 2-(3-ethoxy-4-benzyloxyphenyl)-
1,3-dithiolane 2-(3-methoxy-4-phenethyloxyphenyl)
-1,3-dithiane 2-(3-ethoxy-4-phenethyloxyphenyl)
-1,3-dithiane(37) (31) (32) (33) (35) (34) (38) (39) (40) (41)2- (3-benzyloxy-4-methoxyphenyl)- 1,3-dioxane (42) 2-(3-benzyloxy-4-methoxyphenyl)-1,3-dioxolane (43) 2-(3-benzyloxy-4-methoxyphenyl)-1,3-dithiane ( 44) 2-(3-benzyloxy-4-methoxyphenyl)-1,3-dithiolane (45) 2-(3-benzyloxy-4-methoxyphenyl)-1,3-oxathiolane (46) 4-methyl- 2-(3-benzyloxy-4-methoxyphenyl)
-1,3-dithiolane (47) 4,5-dimethyl-2-(3-benzyloxy-4-methoxyphenyl)-1゜3-dithiolane (48) 2-(2,4-dibenzyloxyphenyl)-
1,3-dioxane (49) 2- (2,4-dibenzyloxyphenyl)
-1,3-dithiane(50)2- (2,4-dibenzyloxyphenyl)
-1,3-dithiolane (51)2- (3,4-dibenzyloxyphenyl)
-1,3-dioxane(52)2- (3,4-dibenzyloxyphenyl)
-1,3-dithiane(53)2- (3,4-dibenzyloxyphenyl)
-1,3-dithiolane(54)2- (4-methylthiophenyl)-1゜3-
Dithiane The compound of the present invention can be easily synthesized by known methods. For example, by reacting a benzaldehyde derivative with a diol such as propanediol or a dithiol such as ethanedithiol, usually using an acid catalyst, a cyclic acetal or cyclic dithioacetal can be obtained under mild conditions and in high yield. In this case, the reaction with the diol is usually carried out while removing water.

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 a heat-sensitive recording layer mainly composed of an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting compound on a support, and can be used with a heat head, a heat pen, or a laser beam. By heating the dye precursor with an electron-accepting compound, a recorded image is obtained by instantaneous reaction between the dye precursor and the electron-accepting compound.
It is disclosed in Publication No. 39 and the like. 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 (crystalline oletlactone), 3.3-bis(p- dimethylaminophenyl) 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-)lichlorophenylleucoauramine, etc.

(3) Xanthine compounds Rhodamine B anilinolactam, Rhodamine Bp-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7-phenyl Fluoran, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7-(3,4-dichloroanilino)fluorane, 3-diethylamino-7-(
2-chloroanilino)fluoran, 3-diethylamino-
6-Methyl-7-anilinofluorane, 3-(N-ethyl-N-tolyl)amino-6-methyl-7-anilinofluorane, 3piperidino-6-methyl-7-anilinofluorane, 3 -(N-ethyl-N-)lyl)amino-6
-Methyl-7-phenylfluorane, 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-anilitofluorane, 3(N-methyl-N-cyclohexyl)amino-6-
Methyl-7-anilitufluorane, 3-(N-ethyl-N-tetrahydrofuryl)amino-6-methyl-7-
Anilitufluoran et al.

(4) Thiazine compounds benzoylleucomethylene blue, p-nitropenzoylleucomethylene blue, etc.

(5) Spiro compounds 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3.3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho-(3-methoxybenzo ) Spiropyran, 3-
Propyl spirobenzopyran etc.

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, 2.2
Bis(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°dihydroxydiphenylsulfone, 3,3'dichloro-4,4°-dihydroxydiphenylsulfone, 3 ,3゛-diallyl-4,
4'-dihydroxydiphenyl sulfone, 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- t-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/vinyl acetate copolymers.

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-methylhensyl) oxalate, etc. Carbonic acid or oxalic acid diester derivatives 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.
/i 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.

(Example 1) 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 and 60 parts of a 2.5% polyvinyl alcohol aqueous solution were ground in a ball mill for 24 hours to obtain a color developer dispersion. 50 parts of 2-(2,4-dimethoxyphenyl)-1,3-dithiane (compound 8) was added to 2
．． The mixture was ground with 120 parts of a 5% aqueous polyvinyl alcohol 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 and mixed well while stirring to prepare a heat-sensitive coating liquid.

50% calcium carbonate dispersion 100 parts 40% zinc stearate 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/ryi to a solid content of 9 g/rd, 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/rd, and dried. A heat-sensitive recording material was prepared.

(Examples 2 to 6) 2-(2,4-dimethoxyphenyl) in Example 1
-2-(3benzyloxyphenyl)-1,3-dithiane instead of -1,3-dithiane (Example 2: Compound 22
), 2-(3-methoxy-4-benzyloxyphenyl)-1,3-dithiolane (Example 3: Compound 36)
, 4-methyl 2-(3-benzyloxy-4-methoxyphenyl)-1,3-dithiolane (Example 4: Compound 4
6) ,2-(2,4-dibenzyloxyphenyl)
-1,3-dithiolane (Example 5: Compound 50), 2-
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that (4-methylthiophenyl)-1,3-dithiane (Example 6: Compound 54) was used.

(Comparative Example 1) 2-(2,4-dimethoxyphenyl) in Example 1
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that -1,3-dithiane was omitted.

(Comparative Example 2) 2-(2,4-dimethoxyphenyl) in Example 1
A heat-sensitive recording material was prepared in the same manner as in the example except that N-hydroxymethylstearamide was used instead of -1,3-dithiane.

(Evaluation) The heat-sensitive recording materials obtained in Examples 1 to 6 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 testing machine manufactured by Taishiki Denki. A printing test was conducted using TH-PMD.

A thermal head with a dot density of 8 dots/■ and a head resistance of 185 Ω is used, with a head voltage of 12 V 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 reflection densitometer. The results are shown in the table below.

(Margin below) Procedural amendment (salmon) July 13, 1990 2゜ Display of incidents name of invention person who makes corrections Relationship with the incident address name 1990 patent application heat sensitive recording material No. 30556

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. Further, Z forms an alkylene chain having 2 or more carbon atoms, and may have an alkyl group side chain. Further, R^1, R^2, and R^3 represent a hydrogen atom, an alkoxy group, an alkylthio group, or an aralkyloxy group which may have a substituent. However, R^1, R^
2. All of R^3 cannot be hydrogen atoms at the same time, and if two of R^1, R^2, and R^3 are hydrogen atoms and the remaining one is an aralkyloxy group, the aralkyloxy The group is not in the para position. )