JPH0664322A - Thermal recording body and its production - Google Patents

Abstract

(57) [Abstract] [Purpose] A heat-sensitive recording material that can maintain high whiteness even when stored under high humidity conditions or high temperature conditions and that has excellent storage stability of recorded images, and such characteristics. Provided is a manufacturing method capable of stably producing the heat-sensitive recording material. A thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, wherein at least a compound represented by the following general formula [Chemical formula 1] is contained in the recording layer. One kind, a polyvalent metal compound, and a water-soluble polymer compound having an acrylonitrile group are contained. In particular, a thermosensitive recording medium in which the water-soluble polymer compound having an acrylonitrile group is a graft copolymer of polyvinyl alcohol and a (acrylamide / acrylic acid / acrylonitrile) copolymer. [Chemical 1]

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 capable of maintaining high whiteness even when stored under high humidity conditions or high temperature conditions and having excellent storage stability of recorded images. And a manufacturing method capable of stably producing a thermosensitive recording medium having such characteristics.

[0002]

2. Description of the Related Art Heretofore, a heat-sensitive recording medium has been well known in which a reaction between a colorless or light-colored basic dye and a color-forming agent is used to bring both color-forming substances into contact with each other by heat to obtain a recorded image. . Such a heat-sensitive recording material generally has insufficient storage stability of a recorded image and has a defect that the recorded image is discolored with time. In particular, when the thermosensitive recording medium is stored under high humidity conditions or high temperature conditions, the recorded image disappears in a relatively short time, and there is a strong demand for improvement.

Therefore, in JP-A-4-53790, a thermosensitive recording medium having improved storage stability of a recorded image by incorporating a compound represented by the following general formula [Chemical formula 1] into the recording layer. Is proposed. However, a coating liquid containing this compound has a problem in stability over time of the coating liquid itself,
When a recording layer is formed by coating and drying on a support immediately after preparing a coating solution, desired whiteness and storage stability of a recorded image can be obtained. After the lapse of time, it was revealed that when the heat-sensitive recording layer was formed by coating and drying on the support, the effect of improving the storage stability of the recorded image was gradually decreased with the passage of time. .

[0004]

In view of the present situation, the present inventors have made the following general formula [Chemical formula 1] contained in the recording layer.
As a result of earnest research on how to use the compound represented by
When a specific water-soluble polymer compound is used in combination with the compound represented by the following general formula [Chemical formula 1], the temporal stability of the coating solution is improved, and as a result, the whiteness of the recording layer and the storage stability of the recorded image are improved. The inventors have found that an extremely excellent effect can be obtained, and have completed the present invention.

[0005]

SUMMARY OF THE INVENTION The present invention comprises:
In a thermosensitive recording medium provided with a recording layer containing a colorless or light-colored basic dye and a coloring agent, at least one compound represented by the following general formula [Chemical Formula 1] in the recording layer, a polyvalent metal compound, And a water-soluble polymer compound having an acrylonitrile group, which is a heat-sensitive recording material.

[0006]

[Chemical 1]

[In the formula, R represents a tert-butyl group, and X represents a hydrogen atom or an alkali metal atom. ]

[0008]

Specific examples of the compound represented by the above general formula [Formula 1] include 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate and 2,2'-
Examples thereof include sodium salt of methylenebis (4,6-di-tert-butylphenyl) phosphate and potassium salt of 2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate. Of course, these compounds may be used in combination of two or more, if necessary. Of these, 2,2'-methylenebis (4,6-di-tert
The sodium salt of -butylphenyl) phosphate is
It is preferable in terms of price and ease of handling.

Examples of the polyvalent metal compound used in combination with the compound represented by the above general formula [Chemical formula 1] include:
Zinc, magnesium, barium, calcium, aluminum, tin, titanium, nickel, cobalt, manganese,
Oxides, hydroxides, sulfides, halides, carbonates, phosphates, silicates, sulfates, nitrates, aluminates or halogen complex salts of metals selected from iron and the like, more specifically, for example , Zinc oxide, zinc hydroxide, zinc aluminate, zinc chloride, zinc sulfide, zinc carbonate, zinc phosphate, zinc silicate, aluminum oxide, aluminum hydroxide, aluminum silicate, aluminum phosphate, calcium carbonate, calcium chloride, In addition to calcium sulfate, calcium silicate, titanium oxide, barium carbonate, barium chloride, barium sulfate, magnesium aluminate, magnesium silicate, magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium phosphate, zinc, calcium, magnesium, etc. Silica surface-treated with a substance containing polyvalent metal ions, and Alin aluminum, calcium stearate, metal salts of higher fatty acids such as zinc stearate.

Among the above-mentioned polyvalent metal compounds, zinc oxide, zinc carbonate, calcium carbonate, calcium silicate,
Magnesium silicate is preferable in terms of price and easy handling, and calcium carbonate is particularly preferable because it is particularly inexpensive. When two or more of these polyvalent metal compounds are used in combination, for example, calcium carbonate and magnesium silicate,
This is one of the preferred embodiments of the present invention because the desired effect can be exhibited more remarkably.

The water-soluble polymer compound having an acrylonitrile group used in the heat-sensitive recording material of the present invention is specifically a graft copolymer of polyvinyl alcohol and a (acrylamide / acrylic acid / acrylonitrile) copolymer, ( Examples include graft copolymers of vinyl alcohol / vinyl acetate) copolymers and (acrylamide / acrylic acid / acrylonitrile) copolymers. Among them, polyvinyl alcohol and (acrylamide / acrylic acid / acrylonitrile) copolymers The graft copolymer of is particularly preferably used because it exerts a particularly remarkable effect.
In addition, although these water-soluble polymer compounds are generally used as a binder, they can also be used as a dispersion aid.

The amount of the compound represented by the general formula [Chemical Formula 1] used is not particularly limited, but generally 1 to 300 parts by weight, preferably about 1 to 300 parts by weight, of the above compound per 100 parts by weight of the color developing agent. It is desirable to adjust in the range of about 1 to 100 parts by weight.

Although the amount of the polyvalent metal compound used is not particularly limited, it is usually about 1 to 500 parts by weight, preferably about 100 parts by weight, relative to 100 parts by weight of the compound represented by the general formula [Chemical Formula 1]. Is adjusted in the range of about 10 to 250 parts by weight. Further, the amount of the water-soluble polymer compound having an acrylonitrile group is not particularly limited, but it is usually 1 to 500 parts by weight, preferably 10 parts by weight with respect to 100 parts by weight of the compound represented by the general formula [Chemical Formula 1]. ~ 30
It is adjusted within the range of about 0 parts by weight.

In the present invention, various known dyes can be used as the colorless or light-colored basic dye constituting the recording layer, and specific examples thereof include the following.
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2) -Dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl)-
3- (2-methylindol-3-yl) phthalide,
3,3-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) -6-dimethylaminophthalide,
3,3-bis (2-phenylindol-3-yl)-
6-Dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-3-yl) -6
-Triarylmethane dyes such as dimethylaminophthalide, 4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leukoauramine, N-2,4,5-trichlorophenylleucoaamine, etc. Diphenylmethane dyes, benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue and other thiazine dyes, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-
Phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho (6'-methoxybenzo) spiropyran, 3-propyl-spiro-
Spiro dyes such as dibenzopyran, lactam dyes such as rhodamine-B-anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine (o-chloroanilino) lactam, 3-dimethylamino-7-methoxyfluorane, 3- Diethylamino-6-methoxyfluorane, 3-diethylamino-7-methoxyfluorane,
3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-
Diethylamino-6,7-dimethylfluorane, 3-
(N-ethyl-p-toluidino) -7-methylfluorane, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino- 7-dibenzylaminofluorane, 3-diethylamino-7-N
-Methyl-N-benzylaminofluorane, 3-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 3- (N-ethyl-p-toluidino) −
6-methyl-7-phenylaminofluorane, 3- (N
-Ethyl-p-toluidino) -6-methyl-7- (p-
Toluidino) fluorane, 3-dimethylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3
-Di-n-butylamino-6-methyl-7-phenylaminofluorane, 3-di-n-pentylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7- (2-carbomethoxy -Phenylamino) fluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-phenylaminofluorane, 3
-Pyrrolidino-6-methyl-7-phenylaminofluorane, 3-piperidino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-
Xylidinofluorane, 3-diethylamino-7- (o
-Chlorophenylamino) fluorane, 3-di-n-butylamino-7- (o-chlorophenylamino) fluorane, 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluorane, 3- (N-methyl-) N-n-
Amyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-Nn-amyl) amino-
6-methyl-7-phenylaminofluorane, 3- (N
-Ethyl-N-isoamyl) amino-6-methyl-7-
Phenylaminofluorane, 3- (N-methyl-Nn)
-Hexyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-Nn-hexyl) amino-6-methyl-7-phenylaminofluorane, 3
-(N-ethyl-N-β-ethylhexyl) amino-6
-Methyl-7-phenylaminofluorane, 3- (N-
Ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-cyclopentyl) amino-6-methyl-7-phenylaminofluorane, 2,2-bis {4- [6'-
(N-Cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthene] -2 '
Fluorane dyes such as -ylamino] phenyl} propane. Of course, it is not limited to these dyes,
A combination of two or more dyes is also possible. Among these dyes, 3-di-n-butylamino-6-methyl-7-
Phenylaminofluorane and 3-di-n-butylamino-7- (o-chlorophenylamino) fluorane are
In particular, it is more preferably used because a thermosensitive recording material having a high whiteness in the white paper portion can be obtained.

Various kinds of compounds are known as the coloring agent used in combination with the above basic dye, and examples thereof include the following. 4-tert-butylphenol, α-naphthol, β-naphthol, 4-acetylphenol,
4-tert-octylphenol, 4,4'-sec-butylidene diphenol, 4-phenylphenol, 4,
4'-dihydroxy-diphenylmethane, 4,4'-isopropylidenediphenol, hydroquinone, 4,
4'-cyclohexylidene diphenol, 4,4'-
(1,3-dimethylbutylidene) bisphenol, 2,
2-bis (4-hydroxyphenyl) -4-methylpentane, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis (6-tert-butyl-3-methylphenol), 4,4'-dihydroxydiphenyl Sulfone, 2,4'-dihydroxydiphenyl sulfone,
4-hydroxy-4'-methyldiphenyl sulfone, 4
-Hydroxy-4'-methoxydiphenyl sulfone, 4
-Hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-3 ', 4'-trimethylene diphenyl sulfone, 4-hydroxy-3', 4'-tetramethylene diphenyl sulfone, 3,4-dihydroxy-
4'-methyldiphenyl sulfone, bis (3-allyl-
4-hydroxyphenyl) sulfone, 1,3-di [2-
(4-hydroxyphenyl) -2-propyl] benzene, hydroquinone monobenzyl ether, bis (4-hydroxyphenyl) acetic acid butyl ester, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,4,4'-trihydroxy Benzophenone,
2,2 ', 4,4'-tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, 4-
Propyl hydroxybenzoate, sec-butyl 4-hydroxybenzoate, pentyl 4-hydroxybenzoate, 4
Phenyl hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, 4-hydroxybenzoic acid-p- Chlorobenzyl, 4
-Hydroxybenzoic acid-p-methoxybenzyl, novolac type phenolic resin, phenolic compounds such as phenolic polymers, benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec-butyl-
4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid, salicylic acid, 3-isopropylsalicylic acid,
3-tert-butylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, 3-chloro-5- (α-methylbenzyl) salicylic acid, 3-phenyl −5- (α,
α-Dimethylbenzyl) salicylic acid, 3,5-di-α-
Aromatic carboxylic acids such as methylbenzyl salicylic acid, and organic acidic substances such as salts of these phenolic compounds and aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin and nickel etc. Of course, the above-mentioned coloring agents can also be used as needed.
One or more species can be used in combination.

The ratio of the basic dye to the color developing agent to be used should be appropriately selected according to the type of the basic dye or the color developing agent to be used and is not particularly limited, but the basic dye 1 is generally used.
About 100 to 700 parts by weight, preferably about 150 to 400 parts by weight, of the coloring agent is used with respect to 00 parts by weight. The coating liquid containing these is generally prepared by using water as a dispersion medium and a stirrer / pulverizer such as a ball mill, attritor, or sand mill to form a basic dye, a colorant, a compound represented by the general formula [Chemical Formula 1], It is prepared by dispersing a specific polyvalent metal compound together or separately, and in particular, a compound represented by the general formula [Chemical Formula 1] is prepared by dissolving at least one polyvalent metal compound and an aqueous solution having an acrylonitrile group. After being dispersed in the coexistence of at least one type of high-molecular polymer, when prepared by blending a basic dye dispersion and a colorant dispersion, a coating solution having more excellent stability over time can be obtained. Is one of the preferred embodiments of the present invention.

As described above, in the present invention, a water-soluble polymer compound having an acrylonitrile group such as a graft copolymer of polyvinyl alcohol and a (acrylamide / acrylic acid / acrylonitrile) copolymer is used as a binder or a dispersion aid. This is an essential condition. Although the reason for using such a water-soluble polymer compound is not clear, it is likely that the acrylonitrile group, which is a strong polar group present in the copolymer, has some action, resulting in stability of the coating solution over time. The properties are extremely efficiently improved. If necessary, acetoacetyl group-modified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, sulfone group-modified polyvinyl alcohol, (vinyl alcohol / vinyl acetate) copolymer and (acrylamide / acrylic acid / allyl acetate) copolymer Graft copolymer with, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene / maleic anhydride copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene A copolymer emulsion or the like can be used together as a binder or a dispersion aid. Then, these binder components are usually blended in the above coating liquid so as to be in the range of 2 to 40% by weight, preferably 5 to 25% by weight of the total solids of the coating liquid.

Various auxiliaries can be further added to the coating liquid, for example, dioctylsulfosuccinic acid sodium salt, dodecylbenzenesulfonic acid sodium salt,
Examples thereof include dispersants such as lauryl alcohol sulfate / sodium salt and fatty acid metal salt, defoaming agents, fluorescent dyes, and coloring dyes. Further, in order to improve the adhesion of dust to the recording head, kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica, inorganic pigments such as activated clay, styrene microballs, nylon powder, polyethylene Powder, urea
Organic pigments such as formalin resin filler and raw starch particles can also be added. Further, a dispersion liquid or emulsion of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax or the like may be added so that sticking does not occur due to contact with a recording device or recording head.

Further, in the heat-sensitive recording material of the present invention, fatty acid amides such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, and coconut fatty acid amide are used as long as they do not inhibit the desired effects of the present invention. , 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-3-methylphenol), 1,1,3-tris (2-methyl) -4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-
Hindered phenols such as tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, p
-Benzylbiphenyl, p- (4-tolyloxy) biphenyl, 1,5-bis (4-methoxyphenoxy) -3
-Oxa-pentane, 1,2-bis (phenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane,
1,2-bis (3-methylphenoxy) ethane, 1-
Ethers such as (2-methylphenoxy) -2- (4-methoxyphenoxy) ethane, 2-naphtholbenzyl ether, dibenzyl terephthalate, 1-hydroxy-2-naphthoic acid phenyl ester, oxalic acid dibenzyl ester, oxalic acid Esters such as di (4-methylbenzyl) ester and oxalic acid di (4-chlorobenzyl) ester, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2-hydroxy-4-benzyloxybenzophenone It is also possible to use an ultraviolet absorber such as the above and various known heat-fusible substances together as a sensitizer. Among these heat-fusible substances, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (phenoxy) ethane, 1- (2-methylphenoxy) -2-
(4-methoxyphenoxy) ethane, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, oxalic acid di (4-chlorobenzyl) ester, p-
Benzylbiphenyl, p- (4-tolyloxy) biphenyl, and 1,5-bis (4-methoxyphenoxy)-
3-Oxa-pentane is more preferable because it exhibits a particularly excellent sensitizing effect in relation to a specific storage stability improver.
The amount of the heat-fusible substance used is not particularly limited, but is generally 50 to 1000 parts by weight, preferably 100 to 500 parts by weight with respect to 100 parts by weight of the basic dye.
It is desirable to use it in the range of parts by weight.

As the support, paper, plastic film, synthetic paper or the like is used, but paper is preferably used in terms of cost and coating suitability. In the present invention, the method for forming the recording layer is not particularly limited, and it can be formed according to a conventionally well-known and conventional technique. For example, a coating solution for a heat-sensitive recording layer is formed on a support by an air knife coater or a blade. Examples of the method include coating and drying with a suitable coating device such as a coater, bar coater, gravure coater, curtain coater, and short dwell coater. Also, there are no particular limitation on the coating amount of the coating liquid, generally dry weight 2~12g / m ^2, it is adjusted preferably in the range of 2 to 8 g / m ^2. An overcoat layer may be provided on the recording layer for the purpose of protecting the recording layer, a protective layer may be provided on the back surface of the support, or an undercoat layer may be provided between the support and the thermosensitive recording layer. Needless to say, it is also possible to provide various known techniques in the field of manufacturing a thermosensitive recording medium, such as applying an adhesive treatment.

[0021]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, unless otherwise indicated, the part and% in an example show a weight part and weight%, respectively.

Example 1 Formation of Undercoat Layer Baking clay (trade name: Ansilex, manufactured by EMC) 100 parts Styrene-butadiene copolymer latex (solid content: 50%) 15 parts 10% aqueous polyvinyl alcohol solution 30 parts water 20 The above composition was mixed and stirred to prepare a coating liquid for the undercoat layer. The obtained coating liquid was applied to 50 g / m ² of high-quality paper so that the coating amount after drying was 10 g / m ^2, and dried to form an undercoat layer.

Preparation of solution A 3-di-n-butylamino-6-methyl-7-phenylaminofluorane 10 parts 1,2-di (3-methylphenoxy) ethane 25 parts methylcellulose 5% aqueous solution 5 parts water 50 parts This composition was ground with a sand mill until the average particle size became 1.0 μm.

Preparation of Solution B 4,4′-isopropylidenediphenol 20 parts Methylcellulose 5% aqueous solution 5 parts Water 40 parts This composition was ground with a sand mill until the average particle size became 1.5 μm.

Solution C Preparation 2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate sodium salt 10 parts Polyvinylpyrrolidone (molecular weight: 10000) 5% aqueous solution 3 parts water 20 parts This composition It was pulverized with a sand mill until the average particle size became 1.5 μm.

Preparation of coating liquid for recording layer 33 parts of C liquid and 10 parts of light calcium carbonate were sufficiently dispersed in 120 parts of water, and then a graft copolymer of polyvinyl alcohol and (acrylamide / acrylic acid / acrylonitrile) copolymer was prepared. After adding 100 parts of a 15% aqueous solution (Polymaron-1560, manufactured by Arakawa Chemical Industry Co., Ltd.),
Silicon oxide pigment (oil absorption 180 ml / 100 g) 15 parts, 3
15 parts of 0% zinc stearate aqueous dispersion was mixed and sufficiently dispersed, and then 65 parts of solution B and 90 parts of solution A were mixed and stirred to obtain a coating liquid for recording layer.

Formation of Recording Layer The coating solution for the recording layer thus obtained was coated on the undercoat layer immediately after preparation of the coating solution, and after 1 day and 3 days, respectively, so that the coating amount after drying was 4 g / m ^2. It was applied and dried to obtain 3 kinds of thermal recording paper.

Example 2 In the preparation of solution C, 2,2'-methylenebis (4,6-
Instead of the sodium salt of di-tert-butylphenyl) phosphate, a mixture of sodium salt of 2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate and magnesium silicate (mixing ratio: 60) / 4
0) (Adeka Arkles F-, manufactured by Asahi Denka Kogyo Co., Ltd.
Three types of thermal recording papers were obtained in the same manner as in Example 1 except that 85) was used.

Example 3 In preparation of solution A, 3-di-n-butylamino-7- (o-chlorophenylamino) was used instead of 3-di-n-butylamino-6-methyl-7-phenylaminofluorane. Fluoran was used instead of 1,2-di (3-methylphenoxy) ethane with oxalic acid dibenzyl ester, and 4-hydroxy-4 was used in place of 4,4′-isopropylidenediphenol in the preparation of solution B. ′ -Isopropoxydiphenyl sulfone was used, and in the preparation of solution C, 2,2′-methylenebis (4,6-di-
2,2'-methylenebis (4,6-di-tert instead of sodium salt of tert-butylphenyl) phosphate
Three kinds of thermal recording papers were obtained in the same manner as in Example 1 except that a mixture of sodium salt of -butylphenyl) phosphate and zinc oxide (mixing ratio: 85/15) was used.

Comparative Example 1 In the preparation of the coating liquid for the recording layer, a silicon oxide pigment was used in place of the light calcium carbonate, and a graft copolymer of polyvinyl alcohol and a (acrylamide / acrylic acid / acrylonitrile) copolymer was prepared. Instead, 15%
Polyvinyl alcohol aqueous solution (Kuraray Co., Ltd., PV
Three types of thermal recording papers were obtained in the same manner as in Example 1 except that A110) was used.

Comparative Example 2 In the preparation of the coating liquid for the recording layer, instead of the graft copolymer of polyvinyl alcohol and (acrylamide / acrylic acid / acrylonitrile) copolymer, a 15% polyvinyl alcohol aqueous solution (Kuraray Co., Ltd., PVA11) was used.
Three types of thermal recording papers were obtained in the same manner as in Example 1 except that (0) was used.

Comparative Example 3 Three types of thermal recording papers were obtained in the same manner as in Example 1 except that a silicon oxide pigment was used in place of the light calcium carbonate in the preparation of the recording layer coating liquid.

Comparative Example 4 In the preparation of the coating liquid for the recording layer, instead of the graft copolymer of polyvinyl alcohol and (acrylamide / acrylic acid / acrylonitrile) copolymer, a 15% polyvinyl alcohol aqueous solution (Kuraray Co., Ltd., PVA11) was used.
Three types of thermal recording papers were obtained in the same manner as in Example 2 except that (0) was used.

Comparative Example 5 In the preparation of the coating liquid for the recording layer, instead of the graft copolymer of polyvinyl alcohol and (acrylamide / acrylic acid / acrylonitrile) copolymer, a 15% polyvinyl alcohol aqueous solution (Kuraray Co., Ltd., PVA11) was used.
Three types of thermal recording papers were obtained in the same manner as in Example 3 except that (0) was used.

The 24 kinds of heat-sensitive recording papers thus obtained were evaluated for quality by the following method, and the results are shown in [Table 1]. [Recording Density] A thermal recording paper was used with a thermal paper coloring tester (TM-PMD type, manufactured by Okura Electric Co., Ltd., applied voltage: 16 V, pulse cycle: 0.51 ms), and pulse width was 0.30 ms.
The recorded density (D ₁ ) was recorded with a Macbeth densitometer (RD
-914, manufactured by Macbeth.

[Temperature Resistance of Recorded Image] The heat-sensitive recording paper after printing is allowed to stand in an atmosphere of 60 ° C. and 10% RH for 24 hours,
The recording density (D ₂ ) was measured again using a Macbeth densitometer. Further, the recording density residual rate (%) was determined by the following formula. Recording density residual rate = D ₂ / D ₁ × 100

[Development of Fog Color] Heat sensitive recording paper at 60 ° C. and 10
After leaving it in an atmosphere of% RH for 24 hours, the fog color density (F) of the white paper portion was measured using a Macbeth densitometer.

[0038]

[Table 1]

[0039]

As is clear from the results shown in Table 1, the thermosensitive recording medium of the present invention is excellent in the storage stability of recorded images, and further, the whiteness under the high temperature condition is lowered due to the improvement of the storage stability. Since the coating liquid for forming a recording layer has very little stability over time, a thermosensitive recording medium having excellent properties can be stably and efficiently produced.

Claims (11)

[Claims] 1. A thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, wherein the recording layer is represented by the following general formula [Chemical formula 1]. A heat-sensitive recording material comprising at least one compound, a polyvalent metal compound, and a water-soluble polymer compound having an acrylonitrile group. [Chemical 1] [In the formula, R represents a tert-butyl group, and X represents a hydrogen atom or an alkali metal atom. ] 2. A compound represented by the general formula [Chemical Formula 1] is 2,
The thermosensitive recording medium according to claim 1, which is 2'-methylenebis (4,6-di-tert-butylphenyl) phosphate. 3. A compound represented by the general formula [Chemical Formula 1] is 2,
The heat-sensitive recording material according to claim 1, which is a sodium salt of 2'-methylenebis (4,6-di-tert-butylphenyl) phosphate. 4. The polyvalent metal compound is (a) zinc oxide, zinc hydroxide, zinc aluminate, zinc chloride, zinc sulfide, zinc carbonate, zinc phosphate, zinc silicate, aluminum oxide, aluminum hydroxide, silica. Aluminum oxide, aluminum phosphate, calcium carbonate, calcium chloride, calcium sulfate, calcium silicate, titanium oxide, barium carbonate, barium chloride, barium sulfate, magnesium aluminate,
Magnesium silicate, magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium phosphate; (b)
Silica surface-treated with a substance containing a polyvalent metal ion selected from zinc, calcium and magnesium; (c) aluminum stearate, calcium stearate, zinc stearate (a), (b), (c) The thermosensitive recording medium according to claim 1, which is at least one selected from the above. 5. The polyvalent metal compound is zinc oxide, zinc carbonate,
The thermosensitive recording medium according to claim 5, which is at least one selected from calcium carbonate, calcium silicate, and magnesium silicate. 6. The heat-sensitive recording material according to claim 6, wherein the polyvalent metal compound is at least two kinds selected from calcium carbonate, calcium silicate and magnesium silicate. 7. A water-soluble polymer compound having an acrylonitrile group is polyvinyl alcohol and (acrylamide.
The heat-sensitive recording material according to claim 1, which is a graft copolymer with an acrylic acid / acrylonitrile) copolymer. 8. The heat-sensitive recording material according to claim 1, wherein the compound represented by the general formula [Chemical Formula 1] is used in an amount of 1 to 100 parts by weight based on 100 parts by weight of the color developing agent. 9. The amount of the polyvalent metal compound used is 10 to 25 with respect to 100 parts by weight of the compound represented by the general formula [Chemical Formula 1].
The thermosensitive recording medium according to claim 1, which is 0 part by weight. 10. The amount of the water-soluble polymer compound having an acrylonitrile group used is Compound 1 represented by the general formula [Chemical Formula 1].
The amount is 10 to 300 parts by weight with respect to 00 parts by weight.
The heat-sensitive recording material described. 11. A compound represented by the general formula [Chemical Formula 1] is dispersed in the presence of at least one polyvalent metal compound and at least one water-soluble polymer compound having an acrylonitrile group, and then a basic dye dispersion is performed. A method for producing a heat-sensitive recording material, which comprises applying a coating solution for a heat-sensitive recording layer prepared by mixing a liquid and a colorant dispersion liquid onto a support and drying the coating solution.