WO2001054916A1

WO2001054916A1 - Thermal recording material

Info

Publication number: WO2001054916A1
Application number: PCT/JP2001/000550
Authority: WO
Inventors: Takashi Matsumoto; Yasuhisa Tsutsumi
Original assignee: Nippon Steel Chemical Co., Ltd.
Priority date: 2000-01-27
Filing date: 2001-01-26
Publication date: 2001-08-02
Also published as: AU2001228839A1

Abstract

A thermal recording material which is excellent in background whiteness and thermal responsiveness and can be inhibited from suffering background coloring during high-temperature storage. The thermal recording material comprises a support and formed thereon a heat-sensitive color-developing layer containing a leuco dye which is colorless or light-colored at ordinary temperature, an organic acid substance which upon heating reacts with the leuco dye to cause the dye to develop a color, and a sensitizer, wherein the organic acid substance comprises 1,1'-methylenedi-2-naphthol, represented by the formula (I), and the sensitizer comprises at least one member selected among m-terphenyl, 4-benzylbiphenyl, 4-acetylbiphenyl, 2-benzyloxynaphthalene, oxalic diester derivatives, terephthalic diester derivatives, diaryloxyethane derivatives, and acetoacetanilide derivatives.

Description

Thermal recording material

Technical field

The present invention is excellent in background whiteness and thermal responsiveness, and suppresses background coloring during high-temperature storage.

It relates to a thermosensitive recording material that can be obtained. book

Background technology

A thermosensitive recording material comprising a support having thereon a thermosensitive coloring layer containing a colorless or pale-colored leuco dye at room temperature, an organic acidic substance which reacts with the leuco dye by heating to form a color, and a sensitizer. It is used in many fields, such as computer output, printers such as calculators, recorders for various measuring devices, fat machines, automatic ticketing machines, thermal copying machines, and labels. As the use of thermal recording materials expands, there are strong demands for improved performance and price. There have been many proposals for new leuco dyes, organic acidic substances or sensitizers to improve performance, but it is difficult to fully satisfy various requirements.

Japanese Patent Application Laid-Open No. 57-399787 proposes the use of 1,1′-methylenedi-2-2-naphthol as an organic acidic substance, but due to its high melting point. In addition, it has the disadvantage of low color density due to poor compatibility with general-purpose dyes. In order to compensate for such a drawback, Japanese Patent Application Laid-Open No. 2-22971 proposes to use 1,1′-methylenedi-2-naphthyl in combination with a specific sensitizer. However, the whiteness and color sensitivity of the background are not practically satisfactory, and the image stability is improved, and the background whiteness and thermal response are excellent. There is no teaching on how to provide a thermal recording material that can be used. DISCLOSURE OF THE INVENTION The present invention has been made in view of such a viewpoint, and an object of the present invention is to excel in the whiteness of the ground and the heat responsiveness, and to maintain the high temperature generated in a car or the like in summer. An object of the present invention is to provide a heat-sensitive recording material capable of suppressing background color development at the time of existence. That is, the present invention provides a colorless or pale-colored leuco dye at room temperature, and a reaction with the leuco dye by heating to form a color. A heat-sensitive recording material comprising a support and a thermosensitive coloring layer containing an organic acid substance to be reacted and a sensitizer, comprising 1,1'-methylenedi1-2-naphthol as the organic acid substance; And sensitizers such as m-terphenyl, 4-pentinolebiphenyl, 4-acetylbiphenyl, 2-benzyloxynaphthalene, oxalic acid diester derivatives represented by the following general formula (1), In the following general formula (2) One or two selected from diester derivatives of terephthalic acid represented by the following general formula (3), diaryloxetane derivatives represented by the following general formula (3) and acetoacetic anilide derivatives represented by the following general formula (4) A heat-sensitive recording material characterized by containing the above.

O O

R3 -O-C- ^ A-C-0-R4

(2)

(In the above general formulas (1) to (4), R ₂ is each independently a hydrogen atom, a nitrogen atom, a CCs saturated alkyl group, a CCe alkenyl group, or a CiCe alkoxy group. R ₃ and R ₄ each independently represent a C i C s alkyl group, a C ₁ -C ₆ alkenyl group or an aralkyl group)

The thermosensitive recording material of the present invention preferably contains 4-isopropoxy-4'-hydroxydiphenylsulfone together with 1,1'-methylenedi122-naphthol as an organic acidic substance. Further, it is also preferable to include a phenol type or epoxy type storage stabilizer in the thermosensitive coloring layer. It is also preferable to provide an overcoat layer on the thermosensitive coloring layer. It is also advantageous to blend an ultraviolet absorber on the thermosensitive coloring layer or in the overcoat layer.

Hereinafter, the present invention will be described in detail.

The leuco dye used in the present invention is a substance that is colorless or pale at room temperature and that reacts with an organic acidic substance by heating to develop a color. Such leuco dyes include, for example, 7'-anilino-13 '-(dibutylamino) -16'-methyltylenolean, 7'-anilino-13'-( N—Echinorare N—I Sopen Cylamino) 1 6'-methylfluorane, 3,3-bis (p-dimethylaminophenyl) 1-6-dimethylaminophthalide, 3— (p-dimethylaminophenyl) 1-3- (2-phenylamino-3_ (Indoligre) phthalide, 3 — (p-dimethylaminophenyl) 1-3 — (1,2 — dimethyl-13 — indolyl) phthalide, 3, 3 — bis (9-ethyl-3, pyridine) 1-5-dimethylaminophthalide, 3,3-bis (2-phenylenol 3-indole) 15-trimethylmethane dyes such as dimethylaminophthalide, and, for example, Diphenylmethane dyes such as 4,4'-bisdimethylaminobenzhydride benzyl ether; thiazine dyes such as benzoyl leucomethylene bull; and 3-methylmethylbenzene Examples include spiro dyes such as pyrrosinaphthopyran, fluoran dyes, and other dyes such as leuco auramin dyes, indole dyes, and indigo dyes. One or more of these leuco dyes can be used. Preferred leuco dyes are 7'-α-di-lino- '3'-(dibutylamino)-'6'-methylfluoran, 7' -_ a-yuri-no- 3 '-(N-ethyl-N-i Sopentylamino) 1 6'-Methylfluoran.

In the present invention, 1,1′-methylenedi-n-2-naphthol (hereinafter referred to as MDN) represented by the following formula is used as the organic acidic substance. HO

The amount of MDN used varies depending on the type of leuco dye and sensitizer used, but is usually 1 to 6 parts by weight, preferably 1.5 parts by weight, per part by weight of leuco dye. ~ 2.5 parts by weight.

MDN may be used alone, but sensitivity may not be sufficient in some cases. In such a case, it is preferable to use MDN in a mixture with a small amount of another organic acidic substance. Specific examples of such other organic acidic substances include, for example, p-octyl phenol, p-tert-butynolepheno / re, p-fueurfenol, p-hydroxyacetophenon, α-naphthol, ρ— Tertiary octenolacatechol, 2,2,1-dihydroxybiphenyl / bisphenol A, 1,1_bis (p-hydroxyphenylenobutan) butane, 2,2—bis (3—methyl-1 4 — Hydroxyphenyl) prono. 2,2 bis (3,5-dimethinole_4—hydroxyphenyl) prono. 2,2 bis (3,5—dichloro mouth 1-4-hydroxyphenolene) pronon, bisphenolone S, 4—isopropoxy-1 4'-hydroxydiphenylsnorrehon, bis (3 —Ari Nore — 4 —Hydroxyphenyl) Snorehon, Bis (3,4—Dihydroxypheno) Sulfone, 1,1 _bis (4—Hydroxypheninole) Cyclohexane, Bis (4—Hee) Droxypheninole) athenole, bis [2- (4-hydroxyphenythio) ethoxy] methane, 4—dimethylhydroxylphthalate, bis (4-hydroxyphenyl) butyl acetate, p—hydroxybenzoate Benzoates, phenols such as 3,5-ditert-butylsalicylic acid, organic carboxylic acids such as benzoic acid, phthalic acid, salicylic acid, salicylic acid Gold Shokushio include Le zinc and the like.

In particular, when 4 isopropoxy-1'-hydroxydiphenylenolenorefone (hereinafter referred to as IPHDS) is contained in the heat-sensitive coloring layer, the sensitivity is excellently improved. Not only that, but it also has excellent image storage stabilization, so it is preferable. 1! When "103" is used in combination with] ^ DN, the ratio is preferably in the range of 1 to 2 parts by weight of IP HD SO.

When another developer is used in combination, the ratio of MDN / total developer or (MDN + IPHDS) / total developer is 50% by weight or more, more preferably 80% by weight. /. It is better to do above.

Further, in the present invention, m-terphenyl, 4-benzylbiphenyl, 4-acetylbiphenyl, 2-benzyloxynaphthalene, oxalic acid represented by the above general formulas (1) to (4) One or more selected from diester derivatives, terephthalic acid ester derivatives, diaryloxetane derivatives, and acetate acetate derivatives are contained in the thermosensitive coloring layer as a sensitizer. Let me do it.

In particular, when 4-acetylacetylbiphenyl, an oxalic acid diester derivative represented by the general formula (1), and an acetate anilide derivative represented by the general formula (4) are contained in the thermosensitive coloring layer. Thus, better thermal responsiveness can be obtained.

The amount of these sensitizers used varies depending on the type of leuco dye and organic acid substance used, but is usually 1 to 6 parts by weight, preferably 1.5 parts by weight per 1 part by weight of leuco dye. ~ 2.5 parts by weight.

Furthermore, in the present invention, other sensitizers are used in combination within a range that does not impair the whiteness of the background, the thermal responsiveness, and the performance of the background coloration during storage at high temperatures, which is the object of the present invention. No problem.

Preferred specific examples of other sensitizers that can be used in the present invention include stearic acid amide, phenol / remitic acid amide, linoleic acid amide, and stearic acid. Nitrogen-containing compounds such as anilide, 4-hydroxybenzoic acid benzyl ester, Benzyloxybenzoic acid benzyl ester, 2—Phenylester naphthoate, 2—Venzinoleestenol naphtoate, 1—Hydroxy-1- 2—Feninolenate naphtoate, 1-n-butynoleestenolate , P — Esthenole compounds such as toluenes phenol phenol, fluorene, fluoranthene, 2, 6 — diisopropyl propylnaphthalene, 3 — benzizoleacenaphthene, 1, 2 — bis- (3, 4 — dimethylphenyl) 1,2-bis (2,4-dimethylthiophenyl) ethane, 1,2—bis (2,4,5—trimethylphenyl) ethane and other aromatic compounds, 4-phenylene Ketone compounds such as zirbiphenyl, 1,4-diethoxynaphthalene, 1,2-diphenoxybenzen, 1,4-diphenoxybenzene, 4 1 (4'-Methyl phenoxy) bi feninole, dipheninoles norehon, 4,4 'disopropoxy dipheninole norehon, 4, 4'-diphenoxy xydieninolethiotenor, benzizole 4 Examples include ether compounds such as thiothiophenyl ether, 1,2-bis (phenoxymethyl) benzene, and sulfur-containing compounds.

The ratio of the other sensitizers to be used together is as follows: m-terphenyl, 4-pentinolebiphenyl, 4-acetinolebiphenyl, 2-benzyloxynaphtalene, the above-mentioned general formula (1) to 1 part by weight of one or more sensitizers selected from oxalic acid diester derivatives, terephthalic acid diester derivatives, diaryloxetane derivatives and acetoacetate anilide derivatives represented by (4) The other sensitizer to be used in combination is 1 part by weight or less, preferably 0.1 part by weight or less.

When a high degree of storage stability is required, it is desirable to include a known storage stabilizer in the thermosensitive coloring layer of the present invention.

Examples of the storage stabilizer include, for example, tris (2,6-dimethyl-4 Tributynole 3 — hydroxybenzyl) isocyanurate, tris (3,5-di-tert-butyl 1-4-hydroxybenzyl) isocyanurate, tris {2-[3 — ( 3,5—di-tert-butyl-1-4-hydroxyphenyl) propionyloxy} ethyl} isocyanurate, 1,3,5—tris (3,5—dimethinole-4-hydroxy) Benzyl) 1,2,4,6—trimethylbenzene, 1,1,3—tris (2—methyl-14-hydroxy-15—tert-butylphenyl) butane, 1,1,3— Tris (2-methyl-1-4-hydroxy-5-cyclohexylphenyl) butane, 4,4'-butylidenebis (2-tert-butyl-1-5-methyl) phenol, 4,4 '-Thobis (2-tert-butyl-5-methyl) phenol, 2 , 2'-Methylene bis (6-tert-butyl-4-methyl) phenol compounds such as phenol, 4 -benzyloxy 4 '-(2 -methylididinoleoxy) diphenylenosulfone, 4,4'-diglycol Examples include epoxy compounds such as sidyloxydiphenyl sulfone, and sodium 1,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate. Preferably, it is a phenol-type storage stabilizer or an epoxy-type storage stabilizer comprising the above-mentioned phenol compound or epoxy compound. These storage stabilizers are usually used in an amount of 0.1 to 10 parts by weight based on 1 part by weight of the leuco dye.

When a higher storage stability, particularly a plasticizer is required, it is advantageous to provide an overcoat layer on the heat-sensitive coloring layer of the present invention. The overcoat layer is formed by appropriately selecting a molding method so as to obtain desired performance. For example, a coating solution is formed using a conventionally known resin component such as polyvinyl alcohol. The coating liquid is coated by a known coating method so as to have an appropriate thickness. However, the overcoat layer It is important to select the condition, especially since providing a thick overcoat layer tends to lower the sensitivity.

When long-term light fastness is required, an ultraviolet absorber is preferably added to the heat-sensitive coloring layer and / or the overcoat layer of the heat-sensitive recording material of the present invention. Examples of the ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-14-methoxybenzophenone, 2-hydroxy-14-benzoxyphenone, 5, 5'-Methylene bis (2—hydroxy 4—methoxy) 2—hydroxybenzophenones, such as benzophenone, 2- (2—hydroxy-5-methinolepheninole) benzotriazole, 2— (2—hydroxy-5-tert-octylphenyl) benzotriazole, 2- (2-hydroxy-13,5-di-tert-butylphenyl) _5—black mouth Benzotriazonole, 2— (2—hydroxy 3,5 dimethoxyminole) benzotriazonole, 2,2′-methylenebis Zotriazolyl) Hue 2— (2—Hydroxyxy 3—Tertiary Butynole 1—5-Norboxoxyphenyl) Benzotriazole Polyethylene Glycol Estenole and Other 2— (2—Hydroxyphenyl) benzotriene Azo / Res, Phenylenosalicylate, Resonoresino-norenomonobenzoate, 2,4-Di-tert-butylphenyl-3,5-Di-tert-butyl-41-Hydroxybenzoate, Hexadecinole-3,5-Di Tertiary butynolee 4-Benzoates such as hydroxybenzoate, 2-ethynole- 1 2 '-ethoxyxanilide, 2-ethoxy 4'-Substituted oxanilides such as dodecyloxanilide, etyl _ α —Cyan-3,3—Diphenylacrylate, Methyl-2—Cyan-3—Methyl-3- (p—Methoxyphenyl) Shiano Aku Li rate such as data re-rate, 2 - (2 - Non-Dorokishi 4 - O-click door S-triazine, 2— (2—hydroxy 4-methoxyphenyl) 1,4,6—diphenyl s—triazine, 2— (2—hydroxy 4-propoxy-5-methinolephenyl-14,6-bis (2,4-di-tert-butylphenyl) -s-triazoles such as triazine and triazines.

Further, various additives can be added to the thermosensitive coloring layer of the present invention according to the use and the like. Examples of such additives include binders for fixing the pigment and the organic acid substance dispersed on the fine particles in a state where they are isolated from each other, for example, polyvinyl alcohol (PVA), latex, and the like. Methynocellulose, carboxymethylcellulose, casein polyacrylate, gelatin, starch or their derivatives, and white pigments added for the purpose of whiteness of the thermosensitive coloring layer, slipperiness of writing instruments, and sticking Examples thereof include calcium carbonate, karyon, clay, talc, and titanium oxide. These additives may be mixed or separately applied onto a support such as paper or film to form a thermosensitive coloring layer. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be specifically described based on examples and comparative examples. In addition, parts represent parts by weight. The test method is as follows.

(1) Color test

The prepared thermosensitive recording paper was subjected to a dynamic color test (24 V, 1.0 m) to measure the color density of the printed portion and the background. In the dynamic color development test, a printing tester (manufactured by Oshoku Denki) was used to measure the color development density using a Macbeth reflection densitometer RD-914. The measurement was carried out by using the method.

(2) Humidity resistance test

The thermal recording paper on which the dynamic color development test was performed is stored in a thermo-hygrostat (50 ° C, 90% relative humidity) for 24 hours, and then the color density of the printed portion and the background is measured using a Macbeth reflection densitometer RD- The measurement was performed using 9 14.

(3) Plasticizer resistance test

Apply a vinyl chloride wrap to the thermal recording paper on which the dynamic color development test was performed, over the entire printing surface. This test thermal recording paper was stored in a dryer (40 ° C) for 24 hours, and then the color density of the printed area and the background was measured using a Macbeth reflection densitometer RD-914. Was.

(4) Heat resistance test

The thermosensitive recording paper on which the dynamic color development test was performed is stored in a thermostatic dryer (100 ° C) for 24 hours, and then the color density of the printed portion and the background is measured using a Macbeth reflection densitometer RD-914. The measurement was performed by the method described below.

(5) Light fastness test

The thermosensitive recording paper subjected to the dynamic color development test was irradiated with light for 12 hours using a fade meter, and then the color density of the printed portion and the background was measured using a Macbeth reflection densitometer RD-914. . Example 1

(1) Adjustment of solution A

7'-anilino-1 3 '-(dibutylamino) 16'-leuco dye 20 g of methylfluoran and 100 g of a 10% aqueous solution of polyvinyl alcohol were sufficiently ground with a ball mill. , Solution A with powder having an average particle size of 0.8 μm suspended Was adjusted.

(2) Adjustment of solution B

20 g of MDN and 100 g of a 10% aqueous solution of polyvinyl alcohol as an organic acidic substance were sufficiently ground with a ball mill to obtain a liquid B with powder having an average particle diameter of 0.8 m suspended. Was adjusted.

(3) Adjustment of solution C

Solution C in which 20 g of m-terphenyl and 100 g of a 10% aqueous solution of polybutyl alcohol as a sensitizer are sufficiently ground with a ball mill, and a powder having an average particle size of 0.8 m is suspended. Was adjusted.

(4) Adjustment of solution D

1,1,3, tris (2-methyl-1-hydroxy-5-cyclohexynolephene) butane 10 g and 10% polybutyla / recorder as storage stabilizer The aqueous solution (100 g) was sufficiently ground by a ball mill to prepare a solution D in which powder having an average particle size of 0.8 μππ was suspended.

(5) Adjustment of liquid

10 g of zinc stearate, 1 g of dimethyl alcohol, and 1 g of calcium carbonate were thoroughly ground in a ball mill together with 100 g of a 10% aqueous solution of polybutyl alcohol to obtain an average particle size of 0. Solution E in which 8 μm powder was suspended was prepared.

(5) Adjustment of solution F

Solution F was prepared in the same manner as solution E except that 10 g of 2,4-dihydroxybenzophenone was added as an ultraviolet absorber when preparing solution E.

(6) Preparation of thermal recording paper

The above dispersions A, B, C and E were mixed at a weight ratio of 1: 2: 2: 1, and 200 g of the mixed solution was added with 50 g of calcium carbonate, and thoroughly dispersed. Paint This coating solution was applied on a base paper and dried, and a thermosensitive recording paper having a coating amount of 6 g Zm ² after drying was prepared.

Example 2

A thermosensitive recording paper was prepared in the same manner as in Example 1 except that the dispersions of A, B, C and E were mixed at a weight ratio of 1: 2: 1: 1 when preparing the coating liquid of Example 1. The test was conducted.

Examples 3, 5, 7, 9, 11, 11, 13 and 15

In preparing the solution C of Example 1, 4-benzylbiphenyl (Example 3), 4-acetylbiphenyl (Example 5), and 2-benzyloxynaphtha were used instead of m-terphenyl. Len (Example 7), di (4-methylbenzyl) oxalate (Example 9), 1,2-diphenoxetane (Example 11), dibenzyl terephthalate (Example 13) or A heat-sensitive recording paper was prepared and tested in the same manner as in Example 1 except that 4-methoxyethoxyacetic acid anilide (Example 15) was used.

Examples 4, 6, 8, 10, 0, 12, 14, and 16

In preparing the solution C of Example 2, 4-benzylbifunyl (Example 4), 4-acetylbifuunil (Example 6), and 2-benzyloxynaphtha were used instead of m-terphenyl. Len (Example 8), di (4-methylbenzyl) oxalate (Example 10), 1,2-diphenoxetane (Example 12), dibenzyl terephthalate (Example 14) Or, a thermosensitive recording paper was prepared and tested in the same manner as in Example 2 except that 4-methoxyethoxy acetate (Example 16) was used.

Example 17

In preparing the solution B of Example 1, MDN and IP HDS were used as organic acidic substances. A thermosensitive recording paper was prepared and tested in the same manner as in Example 1 except that a mixture of 1: 1 was used.

Example 18

A thermosensitive recording paper was prepared in the same manner as in Example 1 except that a mixture of MDN and IPHDS in a ratio of 1: 1 was used when preparing the solution B in Example 5, and the test was conducted. went.

Example 19

A heat-sensitive recording paper was prepared and tested in the same manner as in Example 1 except that, when preparing the coating liquid of Example 1, Liquid D was used instead of Liquid E.

Example 20

A heat-sensitive recording paper was prepared and tested in the same manner as in Example 1 except that in preparing the coating liquid of Example 5, Liquid D was used instead of Liquid E.

Example 21 to 22

On the heat-sensitive recording paper obtained in Example 1 (Example 21) or the heat-sensitive recording paper obtained in Example 19 (Example 22), the applied amount of the dispersion E after drying was 3 g Z m was applied to the Hare by a ^2, after drying, to obtain a heat-sensitive recording paper having an over-coat layer, it was tested.

Example 23 to 24

On the heat-sensitive recording paper obtained in Example 5 (Example 23) or the heat-sensitive recording paper obtained in Example 20 (Example 24), the applied amount of the dispersion E after drying was 3 g / m3. was applied to the Hare by a ^2, after drying, to obtain a heat-sensitive recording paper having an over-coat layer, it was tested.

Example 2 5

Example 22 In the case of overcoating of 2, except that solution F was used instead of solution E, Example 22 A thermal recording paper was prepared and tested in the same manner as in Example 2.

Example 26

A heat-sensitive recording paper was prepared and tested in the same manner as in Example 24, except that the solution F was used instead of the solution E during the overcoating in Example 24.

Example 2 7 (for comparison)

Example 1 was prepared in the same manner as in Example 1 except that the solution E was used in place of the solution C in the preparation of the coating solution of Example 1, that is, the dispersions of A, B, and E were mixed at a weight ratio of 1: 2: 3. A heat-sensitive recording paper was prepared in the same manner as described above and tested.

Example 2 8 (for comparison)

A thermosensitive recording paper was prepared in the same manner as in Example 1 except that bisphenol A was used in place of 1,1'-methylenedi1-2-naphthol when preparing solution B in Example 1. Was done.

Table 1 summarizes the test results of the above examples.

9ΐ

[Τ 挲]

0SS00 / I0Jf / XDd 9I6W / I0 OAV INDUSTRIAL APPLICABILITY The heat-sensitive recording material of the present invention has a heat-sensitive coloring layer formed by combining a specific organic acid substance and a sensitizer, and thus has excellent background whiteness and heat responsiveness. This is a heat-sensitive recording material that can suppress background coloring during high-temperature storage.

Claims

Scope of Claim (1) A thermosensitive coloring layer containing a colorless or pale-colored leuco dye at room temperature, an organic acidic substance capable of forming a color in response to the leuco dye by heating, and a sensitizer is provided on a support. The heat-sensitive recording material provided in item 1 contains 1,1'-methylenedi- 12-naphthol as an organic acidic substance, and has m-terphenyl as a sensitizer, 4-pentinolebiphenyl, 4-acetinolebiphenyl, 2-benzyloxynaphthalene, oxalic acid diester derivative represented by the following general formula (1), terephthalic acid diester derivative represented by the following general formula (2), and the following general formula ( 3) A heat-sensitive material comprising one or more selected from a diaryloxetane derivative represented by the formula (1) and an acetoacetate anilide derivative represented by the following general formula (4): Recording material.

O _{/ =} . O

R3 -0-C ^ -C-0-R4

(2). _{_{_{- CH2 - CH2 - 0 "Q}}} ^

R1 (3)

(In the above general formulas (1) to (4), each of the scales ₁ and ₂ is independently a hydrogen atom, a nodogen atom, a saturated alkyl group of CCe, an alkenyl group of CiCe, Represents an alkoxy group of C ₆ , and the lengths ₃ and ₄ each independently represent an alkyl group of ~ C ₆ , an alkenyl group of CC e or an aralkyl group. (2) The sensitizer is selected from the group consisting of 4 acetylbutyl biunil, an oxalic acid diester derivative represented by the general formula (1), and an acetate anilide derivative represented by the general formula (4) 2. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording material is at least one kind.

(3) The heat-sensitive recording material according to claim 1, wherein the sensitizer is 4-acetylbiphenyl.

(4) The heat-sensitive recording material according to claim 1, which contains, as an organic acidic substance, 4-isopropoxy-14,1-hydroxydiphenylsulfone together with 1,1'-methylenedi22-naphthol.

(5) The heat-sensitive recording material according to claim 1, wherein the heat-sensitive coloring layer contains a phenol type storage stabilizer or an epoxy type storage stabilizer.

(6) The heat-sensitive recording material according to claim 1, which has an overcoat layer on the heat-sensitive coloring layer.

(7) The thermosensitive recording material according to claim 1 or 6, wherein the thermosensitive coloring layer and / or the overcoat layer contains an ultraviolet absorbent.