JPH0692025A - Heat-sensitive recording material - Google Patents

Abstract

(57) [Summary] [Purpose] The present invention relates to a recording material having excellent color development. A heat-sensitive recording material comprising a support and a heat-sensitive recording layer containing a leuco dye and a color developer capable of coloring the leuco dye when heated as a main component, which is used as a sensitivity improver in the heat-sensitive color developing layer. , 4-diethoxynaphthalene and further has an overcoat layer on the heat-sensitive recording layer, and if necessary, a layer containing plastic spherical fine hollow particles of a thermoplastic resin as a main component as an intermediate layer. Set up. [Effect] The color development sensitivity is good, and the recording suitability after storage and the head matching property during recording are excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material, and more particularly to a heat-sensitive recording material excellent in color development.

[0002]

2. Description of the Related Art Various recording materials have been proposed which utilize a color-forming reaction between a colorless or light-colored leuco dye and a color-developing agent which develops color upon contact by heat or pressure.

One of the heat-sensitive recording materials does not need to be subjected to complicated processing such as development and fixing and can be recorded in a short time with a relatively simple device, generates little noise, and is low in cost. It is useful as various recording materials for electronic calculators, facsimiles, ticket vending machines, label printers, recorders and the like.

Color-forming dyes used in heat-sensitive recording materials include, for example, colorless or light-colored leuco dyes having a lactone, lactam or spiropyran ring, and conventional developers include organic acids and phenolic substances. ing. The heat-sensitive recording material using the leuco dye and the color developer is widely used because of its high image density and high whiteness of the background.

On the other hand, as the demand for the thermal recording system has increased in recent years, there has been an increasing demand for high-speed recording.
For this reason, it is strongly desired to develop a recording material capable of coping with the speeding up of the recording apparatus itself.

[0006]

As a high-sensitivity developer, for example, Japanese Patent Application Laid-Open No. 56-1 has been proposed in order to cope with high-speed recording.
44193 and the like propose p-hydroxybenzoic acid esters, and JP-A-59-22793 and the like propose hydroxynaphthoic acid esters. Thermosensitive recording materials using these compounds as color developing agents are The storage stability of parts is inferior. Furthermore, JP-A-59-16568
It has been proposed to use a thioester compound as a color developer in JP-A No. 0, etc., but a heat-sensitive recording material using the compound has high fastness to oils and fats in the image area, but is not very sensitive. In addition, various proposals have been made for increasing the sensitivity by adding various heat-fusible substances, and a diether compound of 1,4-hydroxynaphthalene is proposed in JP-A-60-127189. , Of these ether compounds, aralkyl ether compounds are said to have good thermal sensitivity, while alkyl ether compounds have good thermal sensitivity, but have the drawback that the sensitivity improver sublimes during storage at high temperatures. Practicality is poor. Various proposals for adding various heat-fusible substances as sensitivity improvers have been made public, for example, benzoic acid ester compounds are disclosed in JP-A-57-128592 and JP-A-58-128592. No. 5,798,9, JP-A-6
A phenyl ether derivative is disclosed in Japanese Patent Publication No. 1-31287.
A naphthol derivative is disclosed in JP-A-58-87064.
JP-A-60-82382 proposes a benzylbiphenyl derivative. However, it is hard to say that the thermosensitive recording materials using these color developers or heat-fusible substances are still sufficient in terms of color development sensitivity, background whiteness, storability (image fading, white powder generation, etc.). .

Further, it has been proposed to provide various intermediate layers as a means for improving the recording sensitivity without deteriorating the background whiteness, as disclosed in JP-A-59-5093 and JP-A-59-59.
No. 225987 discloses a method using an intermediate layer containing fine hollow particles as a main component, and JP-A No. 62-5886 proposes a method using non-expandable hollow particles in the intermediate layer. However, the recording materials proposed in these papers have drawbacks such as insufficient coloring sensitivity and poor recording characteristics.

It is an object of the present invention to provide a heat-sensitive recording material which has excellent color development sensitivity, good recording characteristics, is suitable for high speed recording materials, and has high background whiteness.

[0009]

The present invention relates to a heat-sensitive recording material comprising a support and a heat-sensitive recording layer containing a leuco dye and a color developer capable of coloring the leuco dye when heated as a main component. 1,4 as a sensitivity improver in the coloring layer
A heat-sensitive recording material containing diethoxynaphthalene and further having an overcoat layer on the heat-sensitive color developing layer.

The above-mentioned overcoat layer preferably includes those containing a water-soluble polymer as a main component, and examples of the water-soluble polymer include polyvinyl alcohol, starch and its derivatives, celluloses and the like. The overcoat layer containing these water-soluble polymers as a main component can be provided on the thermosensitive coloring layer by a conventionally known method. At this time, since the coating amount after drying is ² to 8 g / m ² , the storage stability becomes good,
Particularly, when the amount is 3 to 5 g / m ² , the thermal sensitivity and the storage characteristics are preferable. If the coating amount of the topcoat layer is small, sufficient barrier properties cannot be obtained, and 8g / m
^When it exceeds ² , the thermal sensitivity is lowered and the practicality of the thermal recording material is lowered. Furthermore, the degree of polymerization of these water-soluble polymers is 10
Those of about 00 to 2000 are preferably used. When the degree of polymerization is low, sufficient barrier properties cannot be obtained, as described above. By these, the barrier property of the overcoat layer becomes good, the sublimation of the sensitivity improver is prevented, and the preservability is remarkably improved.

Further, in the present invention, it is preferable to provide an intermediate layer between the support and the heat-sensitive recording layer, which contains plastic spherical hollow particles of a thermoplastic resin as a main component.

The intermediate layer containing the plastic spherical hollow particles as a main component acts as a heat insulating layer to improve the sensitivity by efficiently utilizing the thermal energy from the thermal head, and further, the average particle diameter of the plastic hollow particles is Two
When the hollowness is 10 μm and the hollow ratio is 90% or more, the flexibility is further improved, the adhesion with the head is improved, and the dot reproducibility is improved.

The hollow particles used in the present invention have a thermoplastic resin as a shell and contain air or other gas inside, and are fine hollow particles which are already in a foamed state, and have an average particle diameter of 2 to Those having a thickness of 10 μm are used.
When the average particle diameter (particle outer diameter) is smaller than 2 μm, there is a production problem such as it is difficult to obtain an arbitrary hollow ratio. Is decreased, the adhesion to the thermal head is decreased, and the effect of improving the sensitivity is decreased. Therefore, such a particle distribution is preferably such that the particle diameter is within the above range and the distribution peaks are uniform with little variation. Further, the fine hollow particles used in the present invention preferably have a hollow ratio of 50% or more, more preferably 90% or more, due to the heat insulating effect. If the hollowness is low, the heat insulating effect is insufficient, so that heat energy from the thermal head is released to the outside of the heat-sensitive recording material through the support, resulting in poor sensitivity improving effect. The hollow ratio mentioned here is the ratio of the outer diameter to the inner diameter of the hollow particles and is represented by the following formula.

Hollow ratio = (inner diameter of hollow particles) / (outer diameter of hollow particles) × 100 The fine hollow particles used in the present invention have a thermoplastic resin as a shell as described above. As a resin,
A copolymer resin mainly containing vinylidene chloride and acrylonitrile is particularly preferable.

Further, since 1,4-diethoxynaphthalene is used, it is excellent in color developing sensitivity, suitable for high speed recording, and has high background whiteness.

In the present invention, an inorganic or / and organic pigment is optionally used in the intermediate layer. In this case, an oil supply amount of 30 ml / 100 g or more, preferably 80 ml / 100 g or more is selected. To be done. As these inorganic and / or organic pigments, one or more of the pigments commonly used in this type of heat-sensitive recording material can be selected. Specific examples thereof include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, inorganic pigments such as surface-treated calcium and silica, and urea-formalin resin. Examples thereof include organic pigments such as styrene / methacrylic acid copolymer and polystyrene resin.

The leuco dyes used in the present invention may be applied alone or in admixture of two or more, and as such leuco dyes, those applied to the recording material of this type may be optionally applied, for example, tri-color dyes. Phenylmethanephthalide type, triallylmethane type, fluorane type, phenothiazine type, thiofluorane type, xanthene type, indophthalyl type, spiropyran type, azaphthalide type, chromenopyrazole type, methine type, rhodamine anilinolactam type,
Leuco compounds such as rhodamine lactam type, quinazoline type, diazaxanthene type and bislactone type are preferably used. Examples of such compounds include those shown below.

3,3-bis (p-dimethylaminophenyl) -phthalide 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide 3,3-bis (p-dimethylaminophenyl) -6 -Diethylaminophthalide 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide 3,3-bis (p-dibutylaminophenyl) phthalide 3-cyclohexylamino-6-chlorofluorane 3-dimethylamino-5 7-Dimethylfluorane 3- (N-methyl-N-isoamylamino) -6-methyl-7-anilinofluorane 3- (N-methyl-N-isobutylamino) -6-methyl-7-anilinoflu Oran 3- (Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluorane 3- (N-methyl-N-a Milamino) -6-methyl-
7-anilinofluorane 3- (N, N-di-n-amylamino) -6-methyl-
7-anilinofluorane 3- (N-methyl-N-cyclohexylamino) -6-
Methyl-7-anilinofluorane 3- (N-methyl-N-iso-propylamino) -6
-Methyl-7-anilinofluorane 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane 3-diethylamino-7,8-benzfluorane 3-diethylamino-7 -Chlorofluorane 3-diethylamino-7-methylfluorane 3-diethylamino-6-methyl-7-chlorofluorane 3-virolidino-6-methyl-7-anilinofluorane 3-diethylamino-6-methyl-7- (M-Trichloroanilino) fluorane 3-diethylamino-7- (o-chloroanilino) fluorane 3-dibutylamino-7- (o-chloroanilino) fluorane 3-diethylamino-6-methyl-7-anilinofluorane 3-dibutyl Amino-6-methyl-7-anilinofluorane 3-diethylamino- - methyl-7- (2 ', 4'-
Dimethylanilino) fluorane 3- (N, N-diethylamino) -5-methyl-7-
(N, N-Dibenzylamino) fluorane benzoyl leuco methylene blue 6'-chloro-8'-methoxybenzoindolinospiropyran 6'-bromo-8'-methoxybenzoindolinospiropyran 3- (2'-hydroxy-4'- Dimethylaminophenyl) -3- (2'-methoxy-5'-chlorophenyl)
Phthalide 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl)
Phthalide 3- (2′-hydroxy-4′-diethylaminophenyl) -3- (2′-methoxy-5′-methylphenyl)
Phthalide 3- (2′-methoxy-4′-dimethylaminophenyl) -3- (2′-hydroxy-4′-chloro-5′-
Methylphenyl) phthalide 3-morpholino-7- (N-propyltrifluoromethylanilino) fluorane 3-pyrrolidino-7-trifluoromethylanilinofluorane 3-diethylamino-5-chloro-7- (N-benzyl-tri Fluoromethylanilino) fluorane 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluorane 3- (N-ethyl-N- p-toluidino) -7- (α-
Phenylethylamino) fluorane 3-diethylamino-7- (o-methoxycarbonylphenylethylfluorane 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane 3-diethylamino-7-piperidinoaminofluorane 2-chloro-3- (N-methyltoluidino) -7- (p
-N-butylanilino) fluorane 3,6-bis (dimethylamino) fluorene spiro (9,3 ')-6'-dimethylaminophthalide 3- (N-ethyl-N-cyclohexylamino) -5
6-benzo-7-α-naphthylamino-4′-bromofluorane 3-diethylamino-6-chloro-7-anilinofluorane 3- (N-ethyl-N-2-ethoxypropylamino)
-6-Methyl-7-anilinofluorane 3- (N-ethyl-N-tetrafurfurylamino) -6
-Methyl-7-anilinofluorane 3-diethylamino-6-methyl-7-mesitidino-
4 ', 5'-benzofluorane 3- (p-dimethylaminophenyl) -3- {1,1-
Bis (p-dimethylaminophenyl) ethylene-2-yl} phthalide 3- (p-dimethylaminophenyl) -3- {1,1-
Bis (p-dimethylaminophenyl) ethylene-2-yl} -6-dimethylaminophthalide 3- (p-dimethylaminophenyl) -3- (1-p-
Dimethylaminophenyl-1-phenylethylene-2-
Yl) phthalide 3- (p-dimethylaminophenyl) -3- (1-p-
Dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide 3- (4′-dimethylamino-2′-methoxy) -3-
(1 "-p-dimethylaminophenyl-1" -p-chlorophenyl-1 ", 3" -butadiene-4 "-yl)
Benzophthalide 3- (4'-dimethylamino-2'-benzyloxy)
-3- (1 "-p-dimethylaminophenyl-1" -phenyl-1 ", 3" -butadiene-4 "-yl) benzophthalide 3-dimethylamino-6-dimethylamino-fluorene-9-spiro-3 '(6'-Dimethylamino) phthalide 3,3-bis {2- (p-dimethylaminophenyl)-
2- (p-methoxyphenyl) ethenyl} -4,5,
6,7-Tetrachlorophthalide 3-bis {1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl} -5,6-dichloro-4,7-dibromophthalide bis (p-dimethylamino Styryl) -1-naphthalenesulfonyl methane bis (p-dimethylaminostyryl)
-1-p-tolylsulfonylmethane and the like.

In the present invention, various electron-accepting compounds such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof can be used as the color developer. Specific examples thereof include the following, but are not limited to these.

4,4'-isopropylidenediphenol, 4,4'-isopropylidenebis-o-methylphenol, 4,4'-sec-butylidenebisphenol, 4,4'-isopropylidenebis (2-tert) −
Butylphenol), zinc p-nitrobenzoate, 1,
3,5-Tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzylisocyanuric acid, 2,2
-(3,4'-dihydroxyphenyl) propane, bis (4-hydroxy-3-methylphenyl) sulfide,
4- {β- (p-methoxyphenoxy) ethoxy} salicylic acid, 1,7-bis (4-hydroxyphenylthio)
3,5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -3-oxapentane, phthalic acid monobenzyl ester monocalcium salt, 4,4′-cyclohexylidene diphenol, 4,4′- Isopropylidene bis (2-chlorophenol), 2,2'-methylene bis (4-methyl-6-tert-butylphenol), 4,4'-butylidene bis (6-tert-butyl-2-methylphenol), 1,1 , 3-Tris (2
-Methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4'-thiobis (6-tert-butyl-2-methylphenol), 4,4'-diphenolsulfone, 4-isopropoxy-4'- Hydroxydiphenyl sulfone, 4-benzyloxy-4′-hydroxydiphenyl sulfone, 4,4′-diphenol sulfoxide, isopropyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, benzyl brotocatechuate,
Stearyl gallate, lauryl gallate, octyl gallate, 1,3-bis (4-hydroxyphenylthio) propane, N, N'-diphenylthiourea, N, N'-di (m-chlorophenyl) thiourea, salicyl Anilid,
Methyl bis- (4-hydroxyphenyl) acetate, bis-
Benzyl (4-hydroxyphenyl) acetate, 1,3-bis (4-hydroxyphenyl) benzene, 4,4-bis (4-hydroxyphenyl) benzene, 2,4-diphenolsulfone, 2,2′-diallyl- 4,4'-hydroxyphenyl sulfone, 3,4-dihydroxy-4 '
-Methyldiphenyl sulfone, 1-acetyloxy-2
-Zinc naphthoate, zinc 2-acetyloxy-3-naphthoate, zinc 2-acetyloxy-1-naphthoate,
α, α-bis (4-hydroxyphenyl) α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, tetrabromobisphenol S, 4,4′-thiobis (2-methylphenol),
4,4'-thiobis (2-chlorophenol) and the like.

In order to produce the heat-sensitive recording material of the present invention, a leuco dye, a color developer, 1,4-diethoxynaphthane and other auxiliaries may be supported and bound on a support. As the binder in this case, various conventional binders can be used in appropriate amounts, and specific examples thereof include the following.

Polyvinyl alcohol, starch and its derivatives, methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose,
Cellulose derivatives such as ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer, styrene /
Maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein and other water-soluble polymers, as well as polyvinyl acetate, polyurethane, polyacrylic ester, poly Methacrylic acid ester, vinyl chloride / vinyl acetate copolymer, ethylene / vinyl acetate copolymer emulsion, styrene / butadiene / acrylic copolymer latex and the like.

Further, in the present invention, various heat-fusible substances can be used in combination as the sensitivity improver, and specific examples thereof include the followings, but the present invention is not limited thereto. . Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and baltimic acid amide, fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate, p-benzyl Biphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, 1-hydroxy-
Phenyl 2-naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl carbonate, glare coal carbonate, dibenzyl terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4 -Dibenzyloxynaphthalene, 1,2-diphenoxyethane, 1,2-bis (3-
Methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1,4-diphenoxybutane,
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, p-
Propagyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyl disulfide, 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.

When the heat-sensitive recording material is obtained according to the present invention, if necessary, an additive component commonly used in this kind of heat-sensitive recording material, for example, a filler, a surfactant, a lubricant, a pressure color-developing preventing agent or the like is used together. You can In this case, as the filler, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, inorganic fine powder such as surface-treated calcium or silica, and urea. -Organic fine powders such as formalin resin, styrene / methacrylic acid copolymer, polystyrene resin and vinylidene chloride resin can be mentioned. As the lubricant, higher fatty acid and its metal salt, higher fatty acid amide, higher fatty acid ester can be used. , Various animal, vegetable, mineral or petroleum waxes.

In the present invention, a layer containing a pigment, a binder, a thermoplastic substance or the like can be provided as another intermediate layer between the intermediate layer and the thermosensitive coloring layer, if necessary.

[0026]

EXAMPLES Next, the present invention will be described in more detail by way of examples.

All parts and percentages shown below are based on weight.

Example 1 The following mixture was ground in a magnetic ball mill for 2 days to prepare {A liquid}, {B liquid}, {C liquid} and {D liquid}.

{A liquid} 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts {B liquid} 4-iso Propoxyphenyl-4'-hydroxyphenyl sulfonate 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts {C liquid} 1,4-diethoxynaphthalene 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts {D liquid } Calcium carbonate 20 parts Methylcellulose 20 parts Water 60 parts Next, {A liquid} 10 parts, {B liquid} 30 parts, {C liquid} 20
Parts and, {D solution} 40 parts and well stirred and mixed by thermal coloring layer forming liquid, the dye deposition amount after drying it on the surface of a commercial fine paper (basis weight 52 g / m ²⁾ is 0.5 g / A thermosensitive coloring layer was provided by coating and drying so as to have m ² .

Topcoat layer forming liquid {E liquid} as follows
Was prepared, and an overcoat layer was formed so that the coating amount after drying was 4 g / m ² .

{E liquid} 10% aqueous solution of polyvinyl alcohol (average degree of polymerization 1800) 50 parts 25% aqueous solution of polyamide epichlorohydrin 8 parts Silica (particle size 1 μ) 1 part 30% dispersion of zinc stearate 30 parts Further, the layer surface was calendered so that the surface smoothness was 500 to 600 seconds to prepare a heat-sensitive recording material.

Example 2 The following intermediate layer forming liquid {F liquid} was added to commercially available high-quality paper (basis weight 5
The surface of ² g / m ² ) was coated and dried so that the weight after drying was 5 g / m ² to obtain an intermediate coated paper. A thermosensitive coloring layer and an overcoat layer were formed on this to obtain a thermosensitive recording material.

{F liquid} Fine hollow particle dispersion (copolymer mainly composed of vinylidene chloride and acrylonitrile) (solid content concentration 32%, average particle size 5 μm, hollow ratio 92%) 30 parts styrene / butadiene co-polymer Polymer latex (concentration of solid content 47%) 20 parts Water 60 parts Comparative Example 1 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the topcoat layer in Example 1 was not provided.

Comparative Example 2 A thermosensitive recording material was prepared in the same manner as in Example 1 except that the following {G liquid} was used instead of {C liquid} in Example 2.

{G liquid} Oxalic acid-p-methylbenzyl ester 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts The thermosensitive recording material prepared as described above was used as a thermosensitive paper coloring property manufactured by Okura Electric Co., Ltd. Printing was performed with a test device, and the color density was measured with a Macbeth densitometer RD-914.
Next, the heat-sensitive recording material was stored under a dry condition at 60 ° C. for 5 hours, and then the recoloring property was observed. The above results are shown in Table 1.

[0036]

[Table 1]

Further, the recording material of Example 2 was extremely excellent in the dot reproducibility of the recording portion.

As is clear from the above results, the heat-sensitive recording material using the sensitivity improver 1,4-diethoxynaphthalene of the present invention and having the overcoat layer has high sensitivity, excellent recoloring characteristics, and finer By having an intermediate layer containing hollow particles as a main component, the dot reproducibility is also excellent and the practicability is extremely high.

[0039]

The recording material of the present invention has good color developing sensitivity,
It has excellent recording suitability after storage and head matching during recording.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Hayakawa 1-3-6 Nakamagome, Ota-ku, Tokyo In stock company Ricoh Co., Ltd. (72) Masafumi Torii 1-3-6 Nakamagome, Ota-ku, Tokyo Shares Company Ricoh

Claims (2)

[Claims] 1. A heat-sensitive recording material comprising a support and a heat-sensitive recording layer comprising a leuco dye and a color developer capable of developing a color when heated as a main component, the heat-sensitive recording layer being laminated as a sensitivity improving agent in the heat-sensitive color developing layer. A heat-sensitive recording material comprising 1,4-diethoxynaphthalene and further having an overcoat layer on the heat-sensitive recording layer. 2. The heat-sensitive recording material according to claim 1, wherein a layer containing plastic spherical fine hollow particles made of a thermoplastic resin as a main component is provided as an intermediate layer between the support and the heat-sensitive recording layer.