JP2001018536A - Heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat response while maintaining plasticizer resistance of an image portion in a heat-sensitive recording material containing a diamic acid derivative as a developer by blending a specific organic acid substance compound and a specific sensitizer compound within a heat-sensitive color developing layer laminated on a support to manufacture the material. SOLUTION: The heat-sensitive recording material is manufactured by laminating a heat-sensitive color developing layer containing a leuco dye and a developer for making the dye develop color when heated as main components on a support. At least one type of organic acid substance compound represented by the formula I (wherein R is a hydrogen atom, alkyl group, nitro group or the like, and X is a bivalent group) and an at least one type of a sensitizer compound represented by formulae II, III or the like are further blended within the color developing layer. Blending amounts of the organic acid substance compound of the formula I and the sensitizer compound of the formulae II, III or the like within the color developing layer are all suitably 1 to 5 g/m2 by dry weight, and an undercoating layer containing a pigment or the like as a main component can be provided between the support and the color developing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material having excellent heat responsiveness and image storability.

[0002]

2. Description of the Related Art A thermosensitive recording material generally comprises a support provided with a thermosensitive coloring layer mainly comprising an electron-donating colorless or light-colored dye precursor and an electron-accepting developer. By heating with a head, hot pen, laser light, etc.,
The dye precursor and the developer react instantaneously, and a recorded image is obtained.
It is disclosed in, for example, Japanese Patent Publication No. 14039. Such a heat-sensitive recording material has advantages such that recording can be obtained with a relatively simple device, maintenance is easy, and noise is less generated.In recent years, computers, facsimile machines, ticket vending machines, label printers, It is used in a wide range of fields as recording materials for recorders and the like.

However, a heat-sensitive recording material using such an electron-donating dye precursor and an electron-accepting color developer has excellent properties such as good appearance, good touch, and high color density. On the other hand, the recorded image area comes in contact with plastics such as polyvinyl chloride, etc., and is decolorized by plasticizers and additives contained in plastics, or comes in contact with chemicals contained in foods and cosmetics, etc. Thus, there is a disadvantage that the storability as a recording material is inferior, for example, the recorded image portion is easily erased or the background portion is colored.

[0004] As means for realizing high storage stability of recorded images, use of a highly reliable color developer has been conventionally proposed. For example, JP-A-58-82788, JP-A-60-82
JP-138522 proposes a phenol sulfone compound, JP-A-61-47292 proposes a metal salt of benzoic acid, and JP-A-62-169681 proposes a substituted salicylic acid compound. When a compound is used as a color developer, the fastness of an image area to a plasticizer is insufficient. Further, as a compound which overcomes such a high plasticizer in an image, a diamic acid derivative and a metal salt thereof are proposed in JP-A-9-267566. However, although these compounds have been confirmed to have the characteristic of having excellent plasticizer resistance in images, their thermal responsiveness was not at a satisfactory level.

[0005]

SUMMARY OF THE INVENTION In view of the above, the present invention provides a heat-sensitive recording material using a diamic acid derivative as a color developer to improve the thermal response while maintaining the plasticizer resistance of the image area. Aim.

[0006]

According to the present invention, a colorless or pale-colored leuco dye is reacted on a support at room temperature with an organic acid substance which reacts with the leuco dye by heating to form a leuco dye. ), The heat-sensitive coloring layer comprises at least one compound represented by the following general formula (1) as the organic acidic substance, and A heat-sensitive recording material is provided, which comprises at least one compound selected from the following compound group 2 as a sensitizer.

Embedded image (In the formula, R represents a hydrogen atom, an alkyl group, a nitro group, a halogen atom, a carboxyl group, a hydroxyl group or an alkoxy group, and X represents a divalent group.) {Compound Group 2}

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[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In the organic acidic substance represented by the general formula (1) used in the present invention, the divalent group represented by X is a divalent group derived from a carbonyl group, a sulfonyl group, an aromatic hydrocarbon, or an aliphatic hydrocarbon. Group, one or more heteroatoms in the main chain, a carbonyl group, a sulfonyl group,
Ester bond, divalent group derived from an aliphatic hydrocarbon containing an aromatic ring, at least one hetero atom, carbonyl group, sulfonyl group, ester bond, alkylene, aliphatic containing a hetero atom in the main chain And a divalent group derived from two aromatic hydrocarbons linked by a hydrocarbon. More specific examples include the following functional groups.

C 2 -C 12 alkylene, phenylene, xylylene,

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Embedded image (N is 1 to 5)

In the present invention, the organic acidic substance represented by the general formula (1) has a particularly remarkable effect on the above-mentioned problems, and a preferable compound is a compound represented by the general formula (2) wherein R is a hydrogen atom or a nitro group. ) And (3).

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Embedded image (Wherein, X represents a divalent group) Specific examples of the divalent functional group represented by X in the compounds represented by the general formulas (2) and (3) are described in the aforementioned general formula (1). It is the same as what was done.

Specific compounds represented by the general formulas (1), (2) and (3) include (1) and (2) in Tables 1 to 3 below.
The compounds (specific example compounds) shown in 3) are mentioned.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

The basic dye precursor (leuco dye) used in the present invention can be used alone or as a mixture of two or more kinds. Examples of such a leuco dye include those used in thermosensitive recording materials. Can be used arbitrarily, and examples thereof include the following. 3,
3-bis (p-dimethylaminophenyl) phthalide,
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6
-Methyl-7-anilinofluoran, 3-N-methyl-
N-butylamino-6-methyl-7-anilinofluoran, 3-N-methyl-N-propylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-propylamino-6 -Methyl-7-anilinofluoran, 3
-N-methyl-N-amylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-amylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-isoamyl Amino-6-methyl-7-anilinofluoran, 3-N-hexyl-N-isoamylamino-6-methyl-7-anilinofluoran, 3-N-methyl-N-cyclohexylamino-6-methyl- 7-anilinofluoran, 3-N-ethyl-N-furanylmethylamino-6-methyl-7-anilinofluoran, 3-diethyl-N-butylamino-7- (2'-fluoroanilino) Fluoran, 3-pyrrodilyl-7-dibenzylaminofluoran, 3-bis (diphenylamino) fluoran, 3-diethylamino-7- (2'-chloroanilino) fluoran, 3 Diethylamino-6-chloro-7
-Anilinofluoran, 3-dibutylamino-7-
(2′-chloroanilino) fluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6
-Methyl-7-chlorofluoran, 3-N-methyl-N
-Cyclohexylamino-6-chlorofluoran, 3-
Diethylamino-6-methyl-7- (2 ′, 4′-dimethylanilino) fluoran, 3-diethylamino-7-
Dibenzylaminofluoran, 3-butylamino-7-
(2′-chloroanilino) fluoran, 3-diethylamino-6-ethoxyethyl-7-anilinofluoran and the like.

In the present invention, various heat-fusible substances can be used alone or as a mixture of two or more as a sensitivity improver and a lubricant. Specific examples include the following. Fatty acids such as stearic acid and behenic acid; fatty acid amides such as stearic acid amide and palmitic acid amide; fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate; Benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, Diphenyl carbonate, benzyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene,
1,2-diphenoxyethane, 1,2-bis (4-methylphenoxyethane), 1,4-diphenoxy-2-butene, 1,2-bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,4-diphenylthiobutane, 1,4-diphenylthio-2-butene, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2 −
Vinyloxyethoxy) biphenyl, p-aryloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyldisulfide, 1,1-
Diphenylethanol, 1,1-diphenylpropanol, p-benzyloxybenzyl alcohol, 1,3-
Phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, 1,2-bis (4-methoxyphenoxy) propane, 1,5-bis (4-methoxyphenoxy) -3- Oxapentane, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, bis (4-chlorobenzyl) oxalate and the like.

In preparing the heat-sensitive recording material of the present invention, an organic acidic substance (color developer), leuco dye, compound group 2 represented by the above general formula (1), (2) or (3) is used. In addition to the sensitizers and heat-fusible substances mentioned above, various materials commonly used for forming thermosensitive recording materials can be used as appropriate. Examples thereof include binders for binding various materials on a support or the like in the heat-sensitive recording layer, and these can be used alone or in combination of two or more. Are as follows.

Polyvinyl alcohol, modified polyvinyl alcohol, starch and its derivatives, methoxycellulose,
Hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, cellulose derivatives such as ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer,
Acrylamide / acrylic ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, modified polyacrylamide,
Water-soluble polymers such as methyl vinyl ether / maleic anhydride copolymer, carboxy-modified polyethylene, polyvinyl alcohol / acrylamide block copolymer, melamine-formaldehyde resin, urea-formaldehyde resin, sodium alginate, gelatin, casein, polyvinyl acetate, Polyurethane, styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, polyacrylic acid, polyacrylate, polymethacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, polyvinyl butyral, polyvinyl Emulsions such as acetal and ethylene / vinyl acetate copolymer.

These may be used alone or as a mixture, and may be cured by adding a crosslinking agent (curing agent) if necessary. The crosslinking agent (curing agent) in this case reacts with the binder, and examples thereof include a glyoxal derivative, a methylol derivative, an epichlorohydrin derivative, an epoxy compound, and an aziridine compound.

Specific examples of the pigment used alone or in combination of two or more in the heat-sensitive recording material include the following. Inorganic fine powders such as silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, calcined kaolin, talc, and surface-treated silica. Organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, vinylidene chloride resin, styrene / acrylic copolymer, and plastic hollow hollow fine particles.

Further, the heat-sensitive recording material of the present invention may optionally contain a pigment, a binder, a crosslinking agent, a lubricant, etc. on the heat-sensitive coloring layer for the purpose of improving the head matching property and the writing property on the recording material. It is possible to provide a protective layer as a component,
In this case, as the pigment, binder, crosslinking agent, and lubricant, the above-described pigment, binder, crosslinking agent, and lubricant (a heat-fusible substance) can be used alone or in combination of two or more.

In the present invention, the general formula (1)
When the organic acid substance represented by the formula (1) and the sensitizer represented by the compound group 2 are used in the thermosensitive coloring layer, the content is 1 to 5 g / m ² , preferably 1 to ² g / m ² in terms of dry weight. ^Two
Is appropriate.

In the present invention, an undercoat layer containing a pigment, a binder and the like as main components can be provided between the support and the thermosensitive coloring layer. The undercoat layer functions as a heat insulating layer, and improves sensitivity by efficiently utilizing thermal energy from a thermal head or the like. As the pigment and the binder resin constituting the undercoat layer, the above-mentioned pigments and binder resins can be used alone or in combination of two or more. In this case, it is desirable to use plastic spherical hollow fine particles as the pigment.

The above-mentioned "plastic spherical hollow fine particles" are fine hollow particles which have a thermoplastic resin as a shell, contain air or other gas inside, and are already in a foamed state, and have an average particle size of 0. 0.2 to 20 μm. If the average particle diameter (particle diameter) is smaller than 0.2 μm, there is a problem in production such as difficulty in obtaining an arbitrary hollow ratio, and there is a problem in cost.
When the particle size is larger than m, the surface smoothness after coating and drying is reduced, so that the adhesion to the thermal head is reduced and the effect of improving the thermal sensitivity is reduced. Therefore, it is preferable that the particles have a particle diameter in the above-mentioned range and a small variation in the particle diameter.

Further, in consideration of the heat insulating effect, the hollow spherical particles of the plastic preferably have a hollow ratio of 40% or more, more preferably 90% or more. When the hollow ratio is low, the heat energy from the thermal head is released to the outside of the heat-sensitive recording material through the support because the heat insulating effect is insufficient, and the effect of improving the thermal sensitivity is poor. Here, the "hollow ratio" is a ratio of the outer diameter to the inner diameter of the hollow fine particles, and is represented by the following formula. Hollow ratio (%) = (inner diameter of hollow fine particles) / (outer diameter of hollow fine particles) × 100

As described above, the plastic hollow spherical fine particles have a shell made of a thermoplastic resin. Examples of the resin include polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylate, and polyacrylate. Examples thereof include acrylonitrile, polybutadiene, and copolymer resins thereof. Among these, a copolymer resin mainly containing vinylidene chloride and acrylonitrile is particularly preferable.

In the present invention, the binder resin used for forming the undercoat layer is appropriately selected from conventionally known water-soluble polymers and / or aqueous polymer emulsions. Specific examples thereof include, as water-soluble polymers, for example, polyvinyl alcohol, starch and derivatives thereof, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose,
Cellulose derivatives such as ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / Maleic anhydride copolymer alkali salt, polyacrylamide,
Examples include sodium alginate, gelatin, casein and the like. Examples of the aqueous polymer emulsion include latexes such as styrene / butadiene copolymer and styrene / butadiene / acrylic copolymer, vinyl acetate resin, vinyl acetate / acrylic acid copolymer, and styrene / acrylic ester copolymer. And emulsions of acrylate resin, polyurethane resin and the like.

In the undercoat layer, together with the plastic spherical hollow fine particles and the binder resin, if necessary, auxiliary additives commonly used in this type of heat-sensitive recording material, for example, fillers, heat-fusible substances, A surfactant, a pressure coloring inhibitor and the like can be used in combination. In this case, specific examples of the filler and the heat-fusible substance include those described above in relation to the heat-sensitive coloring layer component. When plastic spherical hollow fine particles are used for the undercoat layer, other inorganic pigments can be added for the purpose of improving the matching property with the thermal head.

Between the undercoat layer and the thermosensitive coloring layer,
If necessary, a layer containing a pigment, a binder, a heat-fusible substance and the like can be provided as an intermediate layer. Further, the heat-sensitive recording material of the present invention may improve the head matching property at the time of printing, improve the storage stability of the recorded image, and improve the writing property on the recording material and the printing property. It is also possible to provide a protective layer on the substrate. in this case,
As the components constituting the protective layer, the above-mentioned filler, binder resin,
A heat-meltable substance or the like can be used.

In the heat-sensitive recording material of the present invention, a back layer mainly composed of a pigment, a binder resin, a crosslinking agent and the like can be provided on the back surface of the support. Also in this case, the pigment, the binder resin, and the lubricant (a heat-fusible substance) are used as the pigment, the binder resin, and the lubricant.

As the support of the heat-sensitive recording material of the present invention,
In addition to ordinary paper (acidic paper, neutral paper), it is possible to arbitrarily use one that can be applied and processed, for example, synthetic paper,
Polymer films and the like can be mentioned.

In addition, in obtaining the heat-sensitive recording material of the present invention, in addition to the above, additional components commonly used in this kind of heat-sensitive recording material, for example, a surfactant, a pressure color-developing agent, and the like can be used in combination. .

The heat-sensitive recording material of the present invention can be used in any field where a heat-sensitive recording material is conventionally used. Specific examples include facsimile paper, food POS labels, industrial barcode labels, linerless labels, ticket paper, magnetically attached paper, CAD paper, and transparent sensitivity films.

[0033]

Next, the heat-sensitive recording material of the present invention will be described in more detail with reference to examples. The following parts and percentages are all based on weight.

Example 1 A mixture having the following composition was dispersed in a magnetic ball mill [A
Solution] to [Solution E]. [Solution A] 3-N, N-dibutylamino-6-methyl-7-anilinofluoran 10 parts 10% aqueous solution of polyvinyl alcohol 10 parts Water 30 parts [Solution B] Specific compound 1 10 parts 10% aqueous solution of polyvinyl alcohol 10 parts Water 30 parts [liquid C] P527 (silica gel manufactured by Mizusawa Chemical) 10 parts 10% aqueous solution of polyvinyl alcohol 10 parts water 30 parts [liquid D] zinc stearate 10 parts 10% aqueous solution of polyvinyl alcohol 10 parts water 30 parts [liquid E ] {Compound Group 2} Compound (a) 10 parts 10% aqueous solution of polyvinyl alcohol 10 parts Water 30 parts

Further, a mixture having the following composition was stirred and dispersed by a disper to prepare [F solution]. [Solution F] Non-foamable plastic micro hollow particles (solid content: 24%, average particle size: 3 μm, hollowness: 95%) 40 parts Styrene / butadiene copolymer latex 10 parts Water 50 parts

Next, a coating solution for the thermosensitive coloring layer and a coating solution for the undercoat were prepared in the following mixing ratio by using [Solution A] to [Solution F]. (Thermal coloring layer coating solution) [Solution A]: [Solution B]: [Solution C]: [Solution D]: [Solution E] =
1: 4: 2: 1: 1 (undercoat coating solution) [Solution F]: [Solution C] = 2: 1

<Coating of Each Layer> Commercial high quality paper (basis weight 60 g)
/ M ² ) of the undercoat coating solution on the surface with a dry weight of 3
g / m ² to obtain an intermediate coated paper (paper coated with an undercoat layer). On the undercoat layer, a thermosensitive coloring layer coating solution was applied and dried so as to have a dry weight of 2.5 g / m ² to form a thermosensitive coloring layer. Then 1
A calendering treatment was performed at a pressure of 0 kg / cm ² to obtain a heat-sensitive recording material of the present invention.

Example 2 Same as Example 1 except that the compound of (Compound Group 2) (b) was used in place of the compound of (Compound Group 2) (a) in [E Solution] of Example 1. To prepare a thermosensitive recording material.

Example 3 In the same manner as in Example 1 except that the compound of (Compound Group 2) (c) was used in place of the compound of (Compound Group 2) (a) in [E Solution] of Example 1 To prepare a thermosensitive recording material.

Example 4 In the same manner as in Example 1 except that the compound of (Compound Group 2) (d) was used in place of the compound of (Compound Group 2) (a) in [Solution E] of Example 1 To prepare a thermosensitive recording material.

Example 5 Same as Example 1 except that the compound of (Compound Group 2) (e) was used in place of the compound of (Compound Group 2) (a) in [Solution E] of Example 1. To prepare a thermosensitive recording material.

Example 6 Same as Example 1 except that the compound of (Compound Group 2) (f) was used in place of the compound of (Compound Group 2) (a) in [E Solution] of Example 1. To prepare a thermosensitive recording material.

Example 7 Same as Example 1 except that the compound of {Compound Group 2} (g) was used in place of the compound of {Compound Group 2} (a) in [Solution E] of Example 1. To prepare a thermosensitive recording material.

Example 8 Same as Example 1 except that the compound of (Compound Group 2) (h) was used in place of the compound of (Compound Group 2) (a) in [E Solution] of Example 1. To prepare a thermosensitive recording material.

Example 9 Same as Example 1 except that the compound of (Compound 2) (i) was used in place of the compound of (Compound 2) (a) in [E solution] of Example 1. To prepare a thermosensitive recording material.

Example 10 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the specific compound 14 was used in place of the specific compound 1 in [Liquid B] of Example 1.

Example 11 In Example 1 [solution B], specific example compound 14 was used in place of specific example compound 1, and in [solution E], {compound group 2} was replaced with compound (a) { A thermosensitive recording material was prepared in the same manner as in Example 1 except that the compound (b) of Compound Group 2} was used.

Example 12 In Example 1 [solution B], specific example compound 14 was used instead of specific example compound 1, and in [solution E], {compound group 2} was replaced with compound (a) { A thermosensitive recording material was prepared in the same manner as in Example 1, except that the compound (c) of the compound group 2} was used.

Example 13 In Example 1 [solution B], specific example compound 14 was used instead of specific example compound 1, and in [solution E], {compound group 2} was replaced with compound (a) { A thermosensitive recording material was prepared in the same manner as in Example 1 except that the compound (d) of the compound group 2} was used.

Example 14 In Example 1 [solution B], specific example compound 14 was used in place of specific example compound 1, and in [solution E], {compound group 2} instead of compound (a) was replaced with { A thermosensitive recording material was obtained in the same manner as in Example 1, except that the compound (e) of the compound group 2) was used.

Example 15 In Example 1 [solution B], specific example compound 14 was used in place of specific example compound 1, and in [solution E], {compound group 2} instead of compound (a) was replaced with { A thermosensitive recording material was prepared in the same manner as in Example 1 except that the compound (f) of the compound group 2} was used.

Example 16 In Example 1 [solution B], specific example compound 14 was used in place of specific example compound 1, and in [solution E], {compound group 2} was replaced with compound (a) { A thermosensitive recording material was obtained in the same manner as in Example 1, except that the compound of the compound group 2} (j) was used.

Example 17 In Example 1 [solution B], specific example compound 14 was used in place of specific example compound 1, and in [solution E], {compound group 2} instead of compound (a) was replaced with { A thermosensitive recording material was prepared in the same manner as in Example 1 except that the compound (k) of the compound group 2} was used.

Example 18 In Example 1, [solution B], specific example compound 14 was used in place of specific example compound 1, and in [solution E], {compound group 2} instead of compound (a) was replaced with { A thermosensitive recording material was prepared in the same manner as in Example 1 except that the compound (g) of the compound group 2) was used.

Example 19 In Example 1 [solution B], specific example compound 14 was used in place of specific example compound 1, and in [solution E], {compound group 2} instead of compound (a) was replaced with { A thermosensitive recording material was prepared in the same manner as in Example 1 except that the compound (h) of the compound group 2} was used.

Example 20 In Example 1, [solution B], specific example compound 14 was used in place of specific example compound 1, and in [solution E], {compound group 2} was replaced with compound (a) { A thermosensitive recording material was prepared in the same manner as in Example 1 except that the compound (i) of the compound group 2) was used.

Comparative Example 1 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that water was used instead of [E solution].

Comparative Example 2 A thermosensitive recording material was prepared in the same manner as in Example 1 except that dibenzyl oxalate was used in place of the compound (a) of {Compound Group 2} in [Solution E] of Example 1. Obtained.

Comparative Example 3 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that parabenzylbiphenyl was used in place of the compound (a) of {Compound Group 2} in [Solution E] of Example 1. Obtained.

Comparative Example 4 A heat-sensitive recording material was obtained in the same manner as in Example 10, except that water was used instead of [E solution].

Comparative Example 5 A heat-sensitive recording material was prepared in the same manner as in Example 10 except that dibenzyl oxalate was used in place of the compound (a) of {Compound Group 2} in [Solution E] of Example 10. Obtained.

Comparative Example 6 A heat-sensitive recording material was prepared in the same manner as in Example 10 except that parabenzylbiphenyl was used in place of the compound (a) of {Compound Group 2} in [E solution] of Example 10. Obtained.

Comparative Example 7 The same procedure as in Example 1 was repeated except that bisphenol A was used in place of Compound 1 in Example 1 [Solution B], and water was used in place of [Solution E]. A heat-sensitive recording material was obtained.

The following test was performed on the heat-sensitive recording material prepared as described above. Table 4 shows the results.

<Coloring Sensitivity Characteristic Test> Head power 0.45 W / dot, 1-line recording time 10 ms / using a simulator printing experiment apparatus having a thin film head manufactured by Matsushita Parts Co., Ltd.
Pulse width 0.4 ms, 0.6 ms, 0.8 ms, 1.0 under the condition of line and scanning line density of 8 × 3.85 dots / mm
Printing was performed in ms, and the image density was measured with a Macbeth densitometer to evaluate the color sensitivity characteristics.

<Image part preservation test> Head power 0.45 W / dot, 1 line recording time 10 ms / using a simulator printing experiment apparatus having a thin film head manufactured by Matsushita Parts Co., Ltd.
Printing was performed with a pulse width of 0.9 ms under the conditions of line and scanning line density of 8 × 3.85 dots / mm to prepare a pre-test image sample. Three vinyl wrap films (manufactured by Shin-Etsu Polymer) were stacked on the test sample, and a weight of 5 kg was applied to the test sample.
The image density after standing at 15 ° C. for 15 hours was measured with a Macbeth densitometer to evaluate the plasticizer resistance.

[0067]

[Table 4] From the results shown in Table 4, it is clear that the heat-sensitive recording material obtained by combining the organic acidic substance and the sensitizer of the present invention has excellent heat responsiveness and also has excellent plasticizer resistance of the image.

[0068]

The heat-sensitive recording material of the present invention comprising a leuco compound and a color developer as main components uses the compound represented by the general formula (1) as a color developer, and the above-mentioned Compound Group 2 as a sensitizer. It has a heat-sensitive color-developing layer using the compound represented by｝, and is excellent in heat responsiveness, plasticizer resistance of an image, and heat resistance of the background.

Claims (3)

[Claims] 1. A heat-sensitive color-forming layer comprising, as a main component, a colorless or pale-colored leuco dye at room temperature and an organic acid substance capable of reacting with the leuco dye to form a leuco dye on heating. In the recording material, the thermosensitive coloring layer comprises at least one compound represented by the following general formula (1) as the organic acidic substance, and at least one compound selected from the following compound group 2 as a sensitizer: A heat-sensitive recording material comprising: Embedded image (In the formula, R represents a hydrogen atom, an alkyl group, a nitro group, a halogen atom, a carboxyl group, a hydroxyl group or an alkoxy group, and X represents a divalent group.) {Compound Group 2} Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image 2. The heat-sensitive recording material according to claim 1, wherein the organic acidic substance is at least one compound represented by the following general formula (2). Embedded image (In the formula, X represents a divalent group.) 3. The heat-sensitive recording material according to claim 1, wherein the organic acidic substance is at least one compound represented by the following general formula (3). Embedded image (In the formula, X represents a divalent group.)