JPH05254248A - Thermal recording material - Google Patents

Abstract

(57) [Summary] [Object] To provide a thermosensitive recording medium which does not deteriorate the whiteness of a recording layer even when stored under high temperature conditions and which is excellent in preservability of recorded images. The present invention is a thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, and the recording layer is represented by the following general formula [Chemical formula 1]. It is a thermosensitive recording medium containing at least one of the compounds shown. [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 high-sensitivity heat-sensitive recording material having less deterioration in whiteness and excellent storage stability of recorded images.

[0002]

2. Description of the Related Art Heretofore, a heat-sensitive recording material has been well known in which a reaction between a colorless or light-colored basic dye and a coloring agent is utilized to bring both color-forming substances into contact with each other by heat to obtain a recorded image. .. Such a thermosensitive recording medium is relatively inexpensive, and the recording apparatus is compact and maintenance-free, so that it is used in a wide range of fields.

However, the thermosensitive recording medium may be left at a temperature of about 40 ° C. for a long time during transportation or during storage in a warehouse. In that case, a color forming reaction may proceed to cause color fog. Especially for high-sensitivity thermosensitive recording media,
There was a problem that the whiteness was significantly reduced. Therefore, there is a strong demand for a thermosensitive recording medium that does not deteriorate in whiteness even when exposed to high temperature conditions for a long time.

Further, the heat-sensitive recording material generally has a problem in storage stability of a recorded image, and has a drawback that the recorded image is discolored within a relatively short time especially under a high temperature condition. For the purpose of improving the storage stability of the recorded image, a method of using various storage stability improving agents has been proposed, but with the previously proposed storage stability improving agents, sufficient effects cannot be obtained, or, Even if it is effective in improving the storability of a recorded image under high temperature conditions, satisfactory results have not been obtained due to new defects such as reduction in whiteness.

Therefore, there is a strong demand for a thermosensitive recording medium which does not deteriorate the whiteness of the recording layer even when stored under high temperature conditions and which is excellent in the stability of recorded images.

[0006]

In view of the present situation, the inventors of the present invention have conducted extensive studies in order to obtain a thermosensitive recording medium that does not cause a decrease in whiteness and recording density even when exposed to high temperature conditions. As a result, they have found that the above-mentioned problems can be solved by incorporating a specific compound represented by the following general formula into the recording layer, and have completed the present invention.

[0007]

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 color former, at least one compound represented by the following general formula [Chemical formula 1] was contained in the recording layer. It is a characteristic thermosensitive recording medium.

[0008]

[Chemical 1]

(In the formula, R ₁ , R ₂ and R ₃ each represent a hydrogen atom or a C _{1 to} C ₄ alkyl group, and X and Y each represent a hydrogen atom or a hydroxyl group.)

[0010]

Specific examples of the compound represented by the general formula [Chemical formula 1] used in the thermosensitive recording medium of the present invention include the following compounds [Chemical formula 2] to [Chemical formula 7]. ,
It is not limited to these, and two or more kinds may be used in combination.

[0011]

[Chemical 2]

[0012]

[Chemical 3]

[0013]

[Chemical 4]

[0014]

[Chemical 5]

[0015]

[Chemical 6]

[0016]

[Chemical 7]

In the heat-sensitive recording material of the present invention, the amount of the compound represented by the general formula [Chemical Formula 1] used is not particularly limited, but generally 5 to 500 parts by weight with respect to 100 parts by weight of the basic dye. Parts, preferably 10 to 300 parts by weight.

As the colorless or light-colored basic dye constituting the heat-sensitive recording layer, various known dyes can be used, 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-
Triallylmethane dyes such as (1-methylpyrrol-3-yl) -6-dimethylaminophthalide, 4,4'-bis-dimethylaminobenzhydrylbenzyl ether,
N-halophenyl-leukoauramine, N-2,4,5
-Diphenylmethane dyes such as trichlorophenyl leuco auramine, benzoyl leuco methylene blue, p-
Thiazine dyes such as nitrobenzoyl leuco methylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-
Spiro dyes such as dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho (6'-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran, rhodamine-B-anilinolactam, rhodamine (p- Lactam dyes such as nitroanilino) lactam and rhodamine (o-chloroanilino) lactam,
3-Dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-cyclohexylamino-
6-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-butyl)
Amino-6-methyl-7-phenylaminofluorane,
3-di (n-pentyl) amino-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-butyl) amino-
7- (o-chlorophenylamino) fluorane, 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluorane, 3- (N-methyl-Nn-amyl) amino-6-methyl-7-phenyl Aminofluorane, 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- [ Fluoran dyes such as 6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro (phthalide-3,9'-xanthene) -2'-ylamino] phenyl} propane. Of course, the dyes are not limited to these dyes, and two or more dyes may be used in combination.

Among these dyes, 3-di (n-butyl) amino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3-di (N-butyl) amino-7- (o-chlorophenylamino) fluorane,
Using at least one of 3-di (n-pentyl) amino-6-methyl-7-phenylaminofluorane,
Not only the desired effect is more remarkably exhibited, but also a thermosensitive recording material having a high whiteness in the white paper portion can be obtained, so that it is more preferably used.

Various known compounds can be used as the color-forming agent constituting the heat-sensitive recording layer, and specific examples are given below. 4-tert-butylphenol, α-naphthol, β-naphthol, 4-acetylphenol, 4-te
rt-octylphenol, 4,4'-sec-butylidene diphenol, 4-phenylphenol, 4,4'-dihydroxy-diphenylmethane, 4,4'-isopropylidenediphenol, hydroquinone, 4,4'-cyclohexylidenediphenol , 4,4 '-(1,3-dimethylbutylidene) bisphenol, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis (6-tert-butyl-3-methylphenol), 4,
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, 1- [α-
Methyl-α- (4'-hydroxyphenyl) ethyl]-
4- [α ', α'-bis (4'-hydroxyphenyl)
Ethyl] benzene, hydroquinone monobenzyl ether, bis (4-hydroxyphenyl) acetic acid butyl ester, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2 ', 4 4'-tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, 4
-Methyl hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, sec-butyl 4-hydroxybenzoate, pentyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate. Tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, p-chlorobenzyl 4-hydroxybenzoate, p-methoxy 4-hydroxybenzoate. Phenolic compounds such as benzyl, novolac type phenol resin, phenol polymer, benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-se
c-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,
Aromatic carboxylic acids such as 5-di-α-methylbenzyl salicylic acid, and these phenolic compounds, aromatic carboxylic acids and polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin and nickel. Organic acidic substances such as salt. In addition, of course, two or more kinds of the above-mentioned coloring agents can be used in combination, if necessary.

The use ratio of the basic dye and the color developing agent should be appropriately selected according to the types of the basic dye and 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.

In the heat-sensitive recording material of the present invention, since the specific compound represented by the general formula [Chemical Formula 1] is contained in the recording layer, even if a heat-fusible substance is used as a sensitizer, The excellent property that the whiteness is not significantly reduced due to color fog at high temperature is exhibited. Therefore, the present invention exerts a more remarkable effect in a high-sensitivity heat-sensitive recording material using a heat-fusible substance.

As the heat-fusible substance, various known compounds can be used, and examples thereof include stearic acid amide, stearic acid methylene bisamide, stearic acid ethylene bisamide, oleic acid amide, palmitic acid amide, and coconut fatty acid amide. 4,4'-butylidene bis (6-tert-butyl-3-methylphenol), 1,
1,3-tris (2-methyl-4-hydroxy-5-t
ert butylphenyl) butane, 1,13-tris (2
Hindered phenols such as -methyl-4-hydroxy-5-cyclohexylphenyl) butane, p-benzylbiphenyl, p- (4-trioxy) 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- (2-methylphenoxy) -2- (4-methoxyphenoxy) ethane,
Ethers such as 2-naphthol benzyl ether, dibenzyl terephthalate, 1-hydroxy-2-naphthoic acid-phenyl ester, oxalic acid dibenzyl ester,
Esters such as oxalic acid di (4-methylbenzyl) ester and oxalic acid di (4-chlorobenzyl) ester, 2
UV absorbers such as-(2'-hydroxy-5'-methylphenyl) benzotriazole and 2-hydroxy-4-benzyloxybenzophenone, as well as other various heat-fusible substances are used in combination as appropriate sensitizers. be able to.

Among the various heat-fusible substances described above, 1,2-bis (phenoxy) ethane and 1,2-bis (phenoxy) ethane are particularly preferable.
Bis (3-methylphenoxy) ethane has good compatibility with the specific compound represented by the general formula [Chemical formula 1] and has low melt viscosity. Therefore, when these are used in combination, high sensitivity with excellent device characteristics is obtained. A thermal recording material can be obtained.
The amount of the heat-fusible substance contained in the recording layer is not necessarily limited, and is generally 50 to 500 parts by weight, preferably 100 to 100 parts by weight with respect to 100 parts by weight of the basic dye.
It is adjusted in the range of about 300 parts by weight.

The coating liquid for forming the recording layer containing these is generally prepared by mixing the dye, the color former and the above-mentioned general formula [Chemical Formula 1] with a water / dispersion medium and stirring / milling machine such as a ball mill, an attritor or a sand mill. It is prepared by dispersing the compounds and the like together or separately and mixing and stirring them.

In such a coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy group-modified polyvinyl alcohol, sulfone group-modified polyvinyl alcohol, acetoacetyl group-modified are usually used as binders. Polyvinyl alcohol, various modified polyvinyl alcohol such as silicone modified polyvinyl alcohol, styrene / maleic anhydride copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, etc.
-40% by weight, preferably 5-25% by weight. Of course, two or more of these binders can be used in combination.

Further, various auxiliary agents can be added to the coating solution, 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.

In order to improve the adhesion of dust to the recording head, for example, kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, finely particulate anhydrous silica, inorganic pigments such as activated clay, styrene microballs, etc. , Nylon powder, polyethylene powder, urea
Organic pigments such as formalin resin fillers and starch particles can also be added. Further, it is possible to add, for example, a dispersion liquid or emulsion of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax or the like so that sticking does not occur due to contact with a recording device or recording head. it can.

In the heat-sensitive recording material of the present invention, the method for forming the recording layer is not particularly limited, and various known methods can be used. For example, it is formed by coating and drying a coating liquid for forming a recording layer on a support with an appropriate coating device such as an air knife coater, a blade coater, a bar coater, a gravure coater, and a curtain coater.

The coating amount of the coating liquid is not particularly limited, but generally 1.0 to 12 g / m ² , preferably 1.5 by dry weight.
It is adjusted within the range of about 10 g / m ² . As the support, paper, plastic film, synthetic paper and the like are used, but paper is most preferably used in terms of cost and coating suitability.

The thermal recording material of the present invention thus obtained is
Even when exposed to high temperature conditions, the whiteness and recording density are not significantly reduced, and particularly excellent effects as a high-sensitivity thermosensitive recording medium are exhibited. If necessary, a protective layer may be provided on the front surface or the back surface of the thermosensitive recording medium, or an undercoat layer may be provided between the support and the recording layer, and further, an adhesive treatment may be performed. Various well-known techniques in the field of producing a thermal recording material can be appropriately added.

[0032]

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 Fired 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 200 parts The undercoat layer coating solution prepared by mixing and stirring the above composition is applied to a high-quality paper of 50 g / m ² with an application amount of 10 g after drying.
It was applied and dried so as to be / m ² to form an undercoat layer.

Preparation of solution A 3-di (n-butyl) amino-6-methyl-7-phenylaminofluorane 10 parts 1,2-bis (3-methylphenoxy) ethane 25 parts 5% aqueous methylcellulose solution 30 parts water 20 parts This composition was ground with a sand mill until the average particle size was 0.8 μm.

Preparation of Solution B 4,4′-isopropylidenediphenol 30 parts 5% aqueous solution of methylcellulose 30 parts water 70 parts This composition was ground with a sand mill until the average particle size became 1.4 μm.

Preparation of Liquid C 5 parts of the compound of the above-mentioned general formula [Chemical Formula 2] 5% aqueous solution of methylcellulose 5 parts water 10 parts This composition was ground with a sand mill until the average particle size became 1.0 μm.

Formation of thermal recording layer 85 parts of A solution, 130 parts of B solution, 20 parts of C solution, 7 parts of silicon oxide pigment (oil absorption 180 ml / 100 g), 8 parts of light calcium carbonate (oil absorption 90 ml / 100 g), 20 % Polyvinyl alcohol aqueous solution 50 parts, 30% zinc stearate aqueous dispersion 15 parts, and water 10 parts were mixed and stirred to obtain a coating liquid. The resulting coating liquid was applied onto the undercoat layer so that the dry coating amount was 4.5 g / m ^2, and dried to obtain a thermosensitive recording medium.

Example 2 In preparation of solution A of Example 1, 3-di (n-butyl) amino-6-methyl-7-phenylaminofluorane was replaced with 3-diethylamino-7- (o-chlorophenylamino). ) Using fluorane, a thermosensitive recording medium was obtained in the same manner as in Example 1 except that the compound of the general formula [Chemical Formula 3] was used instead of the compound of the general formula [Chemical Formula 2] in the preparation of the liquid C. It was

Example 3 In preparation of solution A of Example 1, 3-di (n-butyl) amino-7 was used instead of 3-di (n-butyl) amino-6-methyl-7-phenylaminofluorane. Using-(o-chlorophenylamino) fluorane, in the same manner as in Example 1 except that the compound of the general formula [Chemical formula 5] was used in place of the compound of the general formula [Chemical formula 2] in the preparation of solution C. A thermosensitive recording medium was obtained.

Example 4 In preparation of solution A of Example 1, 3-di (n-pentyl) amino-6 was used instead of 3-di (n-butyl) amino-6-methyl-7-phenylaminofluorane. -Methyl-
In the same manner as in Example 1, except that the compound of the general formula [Chemical formula 6] was used instead of the compound of the general formula [Chemical formula 2] in the preparation of the C liquid using 7-phenylaminofluorane. I got a record.

Example 5 In preparation of solution A of Example 1, 3- (N-ethyl-N-iso-) was used instead of 3-di (n-butyl) amino-6-methyl-7-phenylaminofluorane. A thermosensitive recording medium was obtained in the same manner as in Example 1 except that amyl) amino-6-methyl-7-phenylaminofluorane was used.

Comparative Examples 1 to 5 Five types of thermal recording materials were obtained in the same manner as in Examples 1 to 5 except that the liquid C was not added in the formation of the thermal recording layers of Examples 1 to 5.

Comparative Example 6 In the preparation of the liquid C of Example 1, 1,1,3-tris (5-cyclohexyl-4-hydroxy-0-tolyl) butane was used in place of the compound of the general formula [Chemical Formula 2]. A thermal recording material was obtained in the same manner as in Example 1 except that the thermal recording material was used.

The 11 kinds of thermal recording materials thus obtained were used in high-speed thermal facsimile (Panafax UF-6
0, manufactured by Matsushita Electric Transport Co., Ltd.). The color density of the obtained recorded image was measured with a Macbeth reflection densitometer (RD-914 type, manufactured by Macbeth Co.), and the results are shown in Table 1.

After recording, the heat-sensitive recording material was recorded at 40 ° C. and 50
After being kept in an atmosphere of% RH for 3 days, the density of the recorded image was measured again with a Macbeth reflection densitometer to evaluate the respective storability under high temperature conditions, and the results are shown in Table 1.

Further, the whiteness of the white paper portion was measured with a Hunter whiteness meter (using a blue filter) before and after being kept in an atmosphere of 40 ° C. and 50% RH for 3 days, and the results are also shown in Table 1.

[0047]

[Table 1]

[0048]

As is clear from the results of Table 1, the thermosensitive recording media obtained in the respective examples of the present invention show little reduction in whiteness and recording density even when stored under high temperature conditions. The recording medium was extremely excellent in storage stability.

Claims (2)

[Claims] 1. A heat-sensitive recording material comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, the recording layer being represented by the following general formula [Chemical formula 1]. A heat-sensitive recording material containing at least one compound. [Chemical 1] (In the formula, R ₁ , R ₂ and R ₃ each represent a hydrogen atom or a C _{1 to} C ₄ alkyl group, and X and Y each represent a hydrogen atom or a hydroxyl group.) 2. The basic dye is 3-di (n-butyl) amino-6-methyl-7-phenylaminofluorane, 3-
Diethylamino-7- (o-chlorophenylamino) fluorane, 3-di (n-butyl) amino-7- (o-chlorophenylamino) fluorane, 3-di (n-pentyl) amino-6-methyl-7-phenylamino The thermal recording medium according to claim 1, which is at least one kind of fluoran.