JPH11291631A - Two-color coloring heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture two-color coloring heat-sensitive recording material of superior coloring properties and storage properties. SOLUTION: A heat-sensitive recording material is provided with a heat- sensitive coloring layer formed of two-layer coloring into different color tones on a substrate of a paper, a plastic sheet, a synthetic sheet or the like, and a first heat-sensitive coloring layer, an intermediate layer, a second heat-sensitive coloring layer to be colored by energy smaller than the coloring energy of the first heat-sensitive layer and a protective layer are laminated successively on the substrate, and a compound represented by the formula and a specific phenol compound are contained in the second heat-sensitive coloring layer. (In the formula, R1 and R2 represent alkyl of 6C or more).

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 two-color heat-sensitive recording material having an improved red recording portion.

[0002]

2. Description of the Related Art A heat-sensitive recording material utilizing a colorless or pale-colored color-forming substance and a color-developing substance capable of coloring the color-forming substance when heated is disclosed in JP-B-43-4160 and JP-B-45-140.
No. 39, etc., which are widely used. In general,
The heat-sensitive recording material is prepared by separately dispersing a developer such as a leuco dye and a phenolic substance into fine particles, and then mixing the two, and then adding additives such as a binder, a sensitizer, a filler, and a lubricant. Is applied to a support such as paper, film, synthetic paper, etc., and the color recording is made by a chemical reaction that occurs when one or both of the leuco dye and the developer are melted and contacted by heating. And a sheet-like heat-sensitive recording material is usually prepared. A thermal printer or the like having a built-in thermal head is used for coloring the heat-sensitive recording sheet. This thermal recording method is (1) compared to other recording methods.
Due to the features such as no noise during recording, (2) no need for development and fixing, (3) maintenance-free, and (4) relatively inexpensive machines,
It is widely used in computer output, printers such as calculators, recorders for medical measurement, automatic ticket vending machines, heat-sensitive recording labels, and the like.

In these fields, attempts have been made to perform multi-color thermal recording using thermal energy differences, and two-color thermal recording systems using leuco dyes have been put into practical use. Two-color thermal recording paper (sheet)
In general, two types of high-temperature and low-temperature color-forming layers, each of which develops a different color tone with a different color-energy on a support, are formed by superimposition, and are roughly classified into the following two types. One of them is a method of obtaining a color tone different from the color tone of the low-temperature coloring layer by mixing colors when the high-temperature coloring layer is colored,
The other is to use a decoloring agent for erasing the low-temperature coloring layer when the high-temperature coloring layer is colored, thereby suppressing the coloring of the low-temperature coloring layer and obtaining the color tone of the high-temperature coloring layer.

[0004]

However, no perfect two-color heat-sensitive recording paper (sheet) has been obtained by any of these methods. For example, the former method has a drawback mainly in two-color separation, and the latter method has a drawback in image storability due to the use of a decoloring agent. At present, while color-developing thermosensitive recording paper is about to be used for long-term display or recording preservation, as with ordinary recording materials, the disadvantage is that two-color thermosensitive recording paper (sheet) is widely used. Is an issue that must be solved in order to be fulfilled. In addition, at present, the performance of the red color recording material does not follow the color density, storage stability, and the like as compared with the black color recording material that has been widely used in the past. SUMMARY OF THE INVENTION It is an object of the present invention to provide a two-color heat-sensitive recording material which is excellent in color density and storage stability especially in a red color recording portion in order to enhance recording characteristics in two-color coloring.

[0005]

Means for Solving the Problems The present inventors have intensively studied to improve the above-mentioned disadvantages of the two-color heat-sensitive recording material and completed the present invention. That is, the present invention
(1) In a heat-sensitive recording material provided with two heat-sensitive coloring layers that develop different colors on the support, the color-forming energy of the first heat-sensitive coloring layer, the intermediate layer, and the first heat-sensitive coloring layer on the support. The second heat-sensitive coloring layer, which forms a color with a small energy, and the protective layer are sequentially laminated, and the second heat-sensitive coloring layer is represented by the following formula (1).

[0006]

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(In the formula (1), R 1 and R 2 each have 6 carbon atoms.
Represents the following alkyl groups. And a compound represented by the following formula (2):

[0008]

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(In the formula (2), R3 represents an alkyl group or cyclohexyl group having 4 or less carbon atoms, and R4 represents an alkyl group having 4 or less carbon atoms.) A color-developing heat-sensitive recording material.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As the alkyl group having 6 or less carbon atoms in R1 and R2 of the formula (1), for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-
Butyl group, sec-butyl group, t-butyl group, n-pentyl (amyl) group, isopentyl (isoamyl) group, n
-Hexyl group and the like. Specific examples of the compound represented by the formula (1) include, for example, 3-diethylamino-7-
Phenoxyfluoran, 3-dibutylamino-7-phenoxyfluoran, 3-dipentylamino-7-phenoxyfluoran, 3- (N-methyl-N-propylamino) -7-phenoxyfluoran, 3- (N -Ethyl-
(N-isopentylamino) -7-phenoxyfluoran and the like, which are used alone or in combination. The compound represented by the formula (1) is disclosed in JP-A-9-3092.
No. 72, it can be synthesized by a known method.

The alkyl group having 4 or less carbon atoms in R 3 and R 4 in the formula (2) includes, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group,
Examples include a sec-butyl group and a t-butyl group. Specific examples of the compound represented by the formula (2) include, for example, 1,
1,3-tris (2-methyl-4-hydroxy-5-t
-Butylphenyl) butane, 1,1,3- (2-ethyl-4-hydroxy-5-t-butylphenyl) butane,
1,1,3- (2-methyl-4-hydroxy-5-t-
(Cyclohexylphenyl) butane and the like. The compound represented by the formula (2) is disclosed in JP-B-63-51115.
And Japanese Patent Application Laid-Open No. 63-132088.

The heat-sensitive recording material of the present invention has an energy smaller than the coloring energy of the support, the first thermosensitive coloring layer, the intermediate layer for enhancing the effect of separating recording colors (two-color separation), and the first thermosensitive coloring layer. , A second heat-sensitive coloring layer and a protective layer.

In forming the heat-sensitive coloring layer on the heat-sensitive recording material of the present invention, the second layer having a small coloring energy as an upper layer is formed.
The thermosensitive coloring layer uses a red coloring compound represented by the formula (1) and a compound represented by the formula (2). The color-forming compound used in the first heat-sensitive color-forming layer having a large color-forming energy serving as a lower layer is selected from the following color-forming compounds, and preferably has a characteristic of an absorption spectrum (for example, in an acetic acid solution) of 550 nm. Those having at least one or more maximum absorption wavelength between 1000 nm and 1000 nm are preferred.

In the first and second heat-sensitive coloring layers provided in the heat-sensitive recording material of the present invention, the color-forming compound is 1 to 50% by weight, the color-developing compound shown below is 5 to 80% by weight, and the binder is 1%. ~ 90% by weight, filler and heat fusible compound each 0
To 80% by weight, and other lubricants, surfactants, defoamers and the like are used in any ratio, for example, 0 to 30% by weight. The weight% is the weight ratio of each component in the thermosensitive coloring layer.

The first heat-sensitive coloring layer serving as the lower layer and the second heat-sensitive coloring layer serving as the upper layer are each intended to obtain a recording color independently, and the following points are considered. That is, the heat quantity Q1 necessary for coloring the first heat-sensitive coloring layer and the heat quantity Q2 necessary for coloring the second heat-sensitive coloring layer of the heat-sensitive recording material are smaller in the latter. In other words, the component ratio of the thermosensitive coloring layer is considered so as to satisfy the relation that the inequality Q1 is larger than Q2. In order to obtain the calorific relationship necessary for coloring the two thermosensitive coloring layers, a coloring compound having a different melting point, a developing compound having a different melting point, when the melting points of the coloring compounds are similar or the same. When a color-developing compound is used, the presence or absence of a compound that lowers the melting point, such as a heat-fusible compound, can be considered.

The first thermosensitive coloring layer on the support has a dry weight of 3 g / m 2 (square meter) or more, preferably 3 to 3 g / m 2 (square meter).
10 g / m @ 2, the second heat-sensitive coloring layer having a dry weight of 0.1 g / m @ 2.
5 to 10 g / m2, preferably 3 to 8 g / m2, are each provided. Further, the first and second heat-sensitive coloring layers are separated from each other by providing an intermediate layer to improve color separation.
Examples of the material used for the intermediate layer include those exemplified as the following binders, and further, if necessary,
A filler, a heat-fusible compound, a lubricant, various surfactants and the like are appropriately selected and used in combination. The intermediate layer weighs 5 g / dry
m2, preferably in the range of 1 to 3 g / m2. Incidentally, 1 g / m @ 2 is about 1 .mu.m in thickness.

The compound represented by the formula (2) is contained in an amount of 1 to 60% by weight, preferably 10 to 30% by weight, based on 100% of the total weight of the second heat-sensitive coloring layer when dried.

The protective layer is formed using the same material as the above-mentioned intermediate layer, and is 0.1 to 5 g / m 2, preferably 2 to 4 g.
/ M2. Incidentally, the protective layer may be a multilayer as required. In the case of a multilayer, layers similar to those of the intermediate layer may be laminated to form a layer, or one of the layers, preferably the outermost layer, may be a layer of an ultraviolet curable resin.

The second heat-sensitive color-forming layer having a small color-forming energy, which is an upper layer, can be used in combination with the compound represented by the formula (1) and a color-forming compound which usually develops a purple-red or yellow color. [A] Fluoran, 3- (N-ethyl-N-isopentylamino) benzo [a] fluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6 Methyl-7-chlorofluorane, 3-cyclohexylamino-6-chlorofluoran, 3- (N-ethyl-Np-tolylamino) -7
-Methylfluorane, 2- {2- [4- (dodecyloxy) -3-methoxyphenyl] ethenyl} -quinoline and the like. The amount used for the second thermosensitive coloring is preferably in a range that does not impair the effects of the present invention, for example, a range that does not exceed the amount of the compound represented by the formula (1).

The color-forming compound used in the first heat-sensitive color-forming layer having a large color-forming energy, which is a lower layer, is selected from blue- or black-colored compounds generally used in pressure-sensitive recording paper and thermosensitive recording paper. . Specific examples thereof include, for example, fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds,
Examples thereof include a thiazine compound, a lactam compound, and a fluorene compound, and those having an absorption spectrum characteristic having at least one or more maximum absorption wavelength between 550 and 1000 nm are preferable.

Among them, fluoran compounds include, for example, 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl- N-cyclohexylamino) -6-methyl-7-anilinofluoran, 3
-(N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluoran, 3- (N-isobutyl-
N-ethylamino) -6-methyl-7-anilinofluoran, 3- [N-ethyl-N- (3-ethoxypropyl) amino] -6-methyl-7-anilinofluoran,
3- (N-ethyl-N-hexylamino) -6-methyl-7-anilinofluoran, 3-dipentylamino-6
-Methyl-7-anilinofluoran, 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tetrahydrofurylamino) -6 Methyl-7-anilinofluoran, 3-
Diethylamino-6-methyl-7- (p-chloroanilino) fluoran, 3-diethylamino-6-methyl-7
-(P-fluoroanilino) fluoran, 3- (p-toluidinoethylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (p
-Toluidino) fluoran, 3-diethylamino-7-
(3,4-dichloroanilino) fluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-ethoxyethylaminofluoran, 3-diethylamino-6-chloro- 7-anilinofluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7-
(O-chloroanilino) fluoran, 3-diethylamino-7- (o-fluoroanilino) fluoran, 3-dibutylamino-7- (o-fluoroanilino) fluoran, 3-diethylamino-7-phenylfluoran, 3
-(P-toluidinoethylamino) -6-methyl-7-
Phenethylfluoran and the like.

Examples of tolylmethane compounds include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone or CVL) and 3,3-bis (p-dimethylamino). Phenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylaminoindole-
3- (yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-
Phenylindol-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- (2-phenylindol-3-yl) -5-dimethyl Aminophthalide, 3-p-dimethylaminophenyl-3- (1-
Methylpyrrole-2-yl) -6-dimethylaminophthalide and the like.

Examples of spiro compounds include 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran,
Benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indoline-2,2'- Benzopyran) and the like, as diphenylmethane compounds, for example, N-halophenyl-leuco auramine,
4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,4,5-trichlorophenylleucouramine and the like; thiazine compounds such as benzoylleucomethylene blue and p-nitrobenzoylleucomethylene blue; Examples of the fluorene-based compound include rhodamine B anilinolactam and rhodamine B-p-chloroanilinolactam, and examples of the fluorene-based compound include 3,6-bis (dimethylamino) fluorenespiro (9,3 ′)-6. '-Dimethylaminophthalide, 3,6-bis (dimethylamino) fluorenespiro (9,3')-6'-pyrrolidinophthalide,
3-dimethylamino-6-diethylaminofluorenespiro (9,3 ')-6'-pyrrolidinophthalide and the like. These coloring compounds are used alone or in combination.

The color-developing compound is not particularly limited as long as it is generally used for pressure-sensitive recording paper or heat-sensitive recording paper.
Specifically, for example, α-naphthol, β-naphthol,
p-octylphenol, 4-t-octylphenol, pt-butylphenol, p-phenylphenol, 1,1-bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) propane (alias: bisphenol A or BPA), 2,2-bis (p-hydroxyphenyl) butane, 1,1-bis (p
-Hydroxyphenyl) cyclohexane, 4,4'-thiobisphenol, 4,4'-cyclohexylidenediphenol, 2,2 '-(2,5-dibromo-4-hydroxyphenyl) propane, 4,4-isopropylidenebis (2-t-butylphenol), 2,2'-methylenebis (4-chlorophenol), 4,4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'- Methoxydiphenylsulfone, 4-hydroxy-4′-ethoxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, 4-hydroxy-4 ′
-Butoxydiphenyl sulfone, methyl bis- (4-hydroxyphenyl) acetate, butyl bis- (4-hydroxyphenyl) acetate, bis- (4-hydroxyphenyl)
Phenolic compounds such as benzyl acetate, 2,4-dihydroxy-2′-methoxybenzanilide, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate,
Dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate,
3,5-di-t-butylsalicylic acid, 3,5-di-α-
Examples include aromatic carboxylic acid derivatives such as methylbenzyl salicylic acid, aromatic carboxylic acids and metal salts thereof.

Binders and fillers are used in the color forming layer, the intermediate layer and the protective layer, if necessary. As a filler that can be used,
For example, calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay,
Alumina, magnesium hydroxide, aluminum hydroxide,
Aluminum oxide, barium sulfate, polystyrene resin,
Urea-formalin resin and the like.

Examples of the binder that can be used include methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, polyvinylpyrrolidone, Polyacrylamide, polyacrylic acid, starch and derivatives thereof, casein, gelatin, water-soluble isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, alkali salt of iso (or diiso) butylene / maleic anhydride copolymer, etc. Water-soluble or polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polystyrene, polyacrylate, polyurethane, styrene / butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid copolymer, hydrophobic polymer emulsion such as composite particles of colloidal silica and acrylic resin, and the like. .

Further, a heat-fusible compound is used for the color-forming layer and the protective layer, if necessary. Examples of the heat-fusible compound that can be used include waxes such as animal and vegetable waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, acetylated aromatic amines, naphthalene derivatives, aromatic ethers, and aromatic carboxylic acids. Acid derivatives, aromatic sulfonic acid ester derivatives, carbonic acid or oxalic acid diester derivatives, biphenyl derivatives, terphenyl derivatives, etc.
Those which are solid at normal temperature and have a melting point of about 70 ° C. or more can be used.

Examples of waxes include wood wax, carnauba wax, shellac, paraffin, montan wax,
Paraffin oxide, polyethylene wax, polyethylene oxide and the like, as higher fatty acids, for example, stearic acid,
Examples of higher fatty acid amides such as behenic acid include stearic acid amide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolbehenic acid amide, methylolstearic acid amide, methylenebisstearic acid amide, and ethylenebisstearin Acid amides and the like; higher fatty acid anilides such as stearic acid anilide and linoleic acid anilide; acetylated aromatic amines such as acetotoluide; naphthalene derivatives such as 1-benzyloxynaphthalene and 2-benzyloxynaphthalene; Benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester and the like include aromatic ethers such as 1,2-diphenoxyethane, 1,4
-Diphenoxyethane, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-methoxyphenoxy) ethane, 1,2-bis (3,4-dimethylphenyl) ethane, 1-phenoxy- 2- (4-chlorophenoxy) ethane, 1-phenoxy-2- (4-methoxyphenoxy) ethane and the like include aromatic carboxylic acid derivatives such as benzyl p-hydroxybenzoate,
Examples of aromatic sulfonic acid ester derivatives include benzyl p-benzyloxybenzoate and dibenzyl terephthalate, for example, p-toluenesulfonic acid phenyl ester, phenylmesitylene sulfonate,
-Methylphenyl mesitylenesulfonate and the like are carbonic acid or oxalic acid diester derivatives, for example, diphenyl carbonate, dibenzyl oxalate, dioxalate (4
-Methylbenzyl) ester, oxalic acid di (4-chlorobenzyl) ester and the like, as biphenyl derivatives,
For example, p-benzylbiphenyl, p-allyloxybiphenyl and the like are terphenyl derivatives such as m-
Terphenyl and the like are each exemplified.

[0029] Lubricants such as zinc stearate, calcium stearate and aluminum stearate, various surfactants, defoaming agents and the like may be added to the color-forming layer, the intermediate layer and the protective layer as required.

Using the above materials, the heat-sensitive recording material of the present invention is prepared, for example, by the following method. That is, first, a color-forming compound for the first heat-sensitive color-forming layer, a color-forming compound represented by the formula (1) for the second heat-sensitive color-forming layer, a compound represented by the formula (2), The compounds are separately pulverized and dispersed together with a binder or other additives as necessary using a disperser such as a ball mill, an attritor, or a sand mill. (When pulverization and dispersion are performed by a wet method, water is usually used as a medium.) ) And mixing to prepare a first thermosensitive coloring layer coating solution and a second thermosensitive coloring layer coating solution, respectively. Separately, a coating solution for the intermediate layer and a coating solution for the protective layer are prepared using a binder or other additives as necessary. Each coating solution is applied and dried on a support such as paper, plastic sheet, synthetic paper or the like in the order of forming the first thermosensitive coloring layer, the intermediate layer, the second thermosensitive coloring layer, and the protective layer, and drying is repeated. A heat-sensitive recording material is obtained. The coating amount of each layer is usually the weight when dried,
Is 3 g / m @ 2 or more, preferably 3 to 10 g.
/ M 2 (the ratio of the color-forming compound to the color-developing compound is usually from 2: 1 to 1:10 by dry weight ratio), and the intermediate layer is 5 g / m 2.
2 or less, preferably 1 to 3 g / m 2, the second thermosensitive coloring layer is 0.5 to 10 g / m 2, preferably 3 to 8 g / m 2,
The protective layer is 0.1 to 5 g / m2, preferably 2 to 4 g / m2.
2

[0031]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" indicates parts by weight.

Example 1 (Formation of a first thermosensitive coloring layer) A mixture having the following composition was pulverized and dispersed using a sand grinder so as to have an average particle size of 1 μm or less. Prepare liquid. [A] solution: 3-diethylamino-7- (o-fluoroanilino) fluoran 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] solution: bis (3-allyl-4-hydroxyphenyl) sulfone 25 parts 25 % PVA aqueous solution 20 parts Water 55 parts Then, the respective preparations were mixed in the following proportions to prepare a first thermosensitive coloring layer coating liquid, and the weight of the white polyester film having a thickness of 188 μm when dried was 6 g / m 2. The first thermosensitive coloring layer of black color is formed by coating and drying. [A] solution 14 parts [B] solution 28 parts 40% styrene / acrylate copolymer emulsion 8 parts

(Formation of Intermediate Layer) On the first thermosensitive coloring layer, 4
A 0% styrene / acrylic acid ester copolymer emulsion is applied so as to have a dry weight of 1 g / m 2 and dried to form an intermediate layer.

(Formation of Second Thermosensitive Coloring Layer) A mixture having the following composition is pulverized and dispersed using a sand grinder so that the average particle size becomes 1 μm or less, to prepare solutions [C] and [D]. . [C] Solution: 25 parts of a coloring compound of the formula (1) (3- (N-ethyl-N-isopentylamino) -7-phenoxyfluorane 25 parts 25% PVA aqueous solution 20 parts water 55 parts [D] Solution: Compound of formula (2) (1,1,3-tris (2-methyl-4-hydroxy-5-t-cyclohexylphenyl) butane 25 parts 25% PVA aqueous solution 20 parts Water 55 parts Then, each prepared solution was prepared as follows. The second thermosensitive coloring layer coating solution was prepared by mixing at a ratio to prepare a second thermosensitive coloring layer coating solution, applied to the above-mentioned intermediate layer so as to have a dry weight of 7 g / m @ 2, and dried to form a red coloring second thermosensitive coloring layer. [C] solution 14 parts [B] solution 28 parts [D] solution 14 parts 40% styrene / acrylate copolymer emulsion 8 parts

(Formation of Protective Layer) Next, a protective layer coating solution having the following composition is prepared, and is coated and dried on the second thermosensitive coloring layer so that the dry weight becomes 2 g / m 2. 20% colloidal silica dispersion 20 parts 40% styrene / acrylic acid ester copolymer emulsion 10 parts Further ultraviolet curing resin (trade name: Best Cure UV)
HAKURI OP varnish UP-2, TANK TOKA CORPORATION
Is transferred to about 1 g / m @ 2 using an RI tester and is fixed by irradiating ultraviolet rays to obtain a two-color heat-sensitive recording material of the present invention.

Example 2 In place of the compound of the formula (2) of Example 1, 1,1,3-
Using (2-methyl-4-hydroxy-5-t-butylphenyl) butane, the heat-sensitive recording material of the present invention is obtained in the same manner as in Example 1.

Example 3 In place of the compound of the formula (2) of Example 2, 1,1,3-
Using (2-ethyl-4-hydroxy-5-t-butylphenyl) butane, the heat-sensitive recording material of the present invention is obtained in the same manner as in the examples.

Example 4 A two-color color heat-sensitive recording material of the present invention was prepared in the same manner as in Example 1 except that the 25% BPA dispersion obtained by pulverizing and dispersing in the same manner as in Example 1 was used instead of the liquid [B]. Get.

Example 5 In the same manner as in Example 1 except that the 25% dispersion of 4-hydroxy-4'-isopropoxydiphenylsulfone obtained by pulverization and dispersion in the same manner as in Example 1 was used instead of the solution [B]. To obtain the two-colored heat-sensitive recording material of the present invention.

Example 6 Example 25 was repeated using the 25% 3-dibutylamino-6-methyl-7-anilinofluoran dispersion obtained by pulverizing and dispersing in the same manner as in Example 1 except for the solution [A]. In the same manner as in 1, the two-color heat-sensitive recording material of the present invention is obtained.

COMPARATIVE EXAMPLE 1 In Example 1, 3- (N-ethyl-N-isopentylamino) benzo [a] fluoran was used in place of the compound of the formula (1) in Example 1, except that the solution [D] was used. A thermosensitive recording material for comparison is obtained in the same manner as described above. Tables 1 and 2 show the quality performance of the present invention and the comparative thermosensitive recording material obtained as described above.

[0042]

Table 1 Table 1 Results of quality performance test Background 1) Red density 2) Red moisture resistance 3) Red moisture resistance 4) Example 1 0.03 1.42 0.07 95% Example 2 0.04 1.44 0.07 97% Example 3 0.04 1.44 0.07 96% Example 4 0.03 1.40 0.06 91% Example 5 0.03 1.43 0.06 93% Example 6 0.04 1.49 0.0999% Comparative Example 1 0.06 0.60 0.45 79%

[0043]

Table 2 Results of quality performance test Red light fastness 5) Red light fastness 6) Black density 7) Black moisture fastness 8) Black light fastness 9) Example 1 0.10 92% 1.64 97% 98% Example 2 0.10 93% 1.66 99% 100% Example 3 0.10 93% 1.65 98% 99% Example 4 0.09 95% 1.60 94% 99% Example 5 0.09 96% 1.67 95% 98% Example 6 0.10 99% 1.70 99% 100% Comparative Example 1 0.44 79% 1.60 91% 97%

1) Background: The value of an uncolored sample measured by a gray colorimeter of a Macbeth reflection densitometer (RD-914). 2) Red density: printing pressure 1 kg / cm2, 100 using hot plate
A value obtained by measuring the density at which color was developed by pressing a sample at 5 ° C. for 5 seconds using a red measuring unit of a Macbeth reflection densitometer. 3) Red humidity resistance: The uncolored sample is 55 ° C. and the relative humidity is 90%.
The value of the background measured by the red measuring unit of the Macbeth reflection densitometer after being left in the humidity chamber for 24 hours. 4) Red moisture resistance: The sample colored at 100 ° C. was 55
Percentage of remaining color density (%) measured by a red measuring unit of a Macbeth reflection densitometer after standing for 24 hours in a humidity chamber at 90 ° C. and a relative humidity of 90%. 5) Red lightfastness: a value measured by a Macbeth reflection density type red measuring part after leaving an uncolored sample left under a 5,000 lux fluorescent lamp for one week.

6) Red lightfastness: A red color density remaining rate (%) measured by a Macbeth reflection density type red measuring unit after the sample colored at 100 ° C. was left under a fluorescent lamp of 5,000 lux for a week. 7) Black density: A value obtained by measuring the density at which the sample was pressed at 50 ° C. for 5 seconds at a printing pressure of 1 kg / cm 2 (square centimeter) using a hot plate to develop a color using a gray color measuring unit of a Macbeth reflection densitometer. 8) Moisture resistance to black: 55 samples obtained at 150 ° C.
Percentage of color density remaining (%) measured by a gray color measuring unit of a Macbeth reflection densitometer after standing in a humidity chamber at 90 ° C. and a relative humidity of 90% for 24 hours. 9) Black lightfastness: The sample colored at 150 ° C.
The residual ratio (%) of the color density measured by a Macbeth reflection density type gray color measuring unit after being left for one week under a fluorescent light of 00 lux.

As is clear from the table, the two-color heat-sensitive recording material of the present invention has a particularly high red color density, and has good storability of the background portion and the chromogenic portion. Are better.

[0047]

According to the present invention, a two-color heat-sensitive recording material having remarkably excellent color developability and storage stability was obtained.

Claims (1)

[Claims] 1. A thermosensitive recording material comprising a support and two heat-sensitive coloring layers each of which develops a different color tone on a support, wherein the first heat-sensitive coloring layer, the intermediate layer and the first heat-sensitive coloring layer are formed on the support. The second heat-sensitive coloring layer, which forms a color with an energy smaller than the energy, is sequentially laminated so as to form a protective layer, and the second heat-sensitive coloring layer has the following formula (1). (In the formula (1), R 1 and R 2 represent an alkyl group having 6 or less carbon atoms.) A compound represented by the following formula (2): (In the formula (2), R3 represents an alkyl group or cyclohexyl group having 4 or less carbon atoms, and R4 represents an alkyl group having 4 or less carbon atoms). material.