JPH07266708A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material excellent in recording sensitivity and the preservability of a recording image against a plasticizer and reduced in background fog. CONSTITUTION:In a thermal recording material wherein a recording layer containing a colorless or light-colored leuco dye and a coupler is provided on a support, as the coupler, 4,4'-bis(p-toluenesulfonylaminocarbonylamino) diphenylmethane and 1,3-bis [alpha-methyl-alpha-(4'-hydroxyphenyl)ethyl]benzene are together used.

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 using a reaction between a leuco dye and a color-developing agent, and more particularly to a heat-sensitive recording material having excellent recording sensitivity and storability of a recorded image and having less background fog. .

[0002]

2. Description of the Related Art Heretofore, a heat-sensitive recording material has been well known in which a colorless or light-colored leuco dye and a color developing agent are colored by utilizing heat energy of a heat-sensitive head or the like. Such a thermal recording medium has been used as a recording medium for facsimiles and various computers because it is relatively inexpensive and the recording device is compact and its maintenance is relatively easy.

In recent years, recording speeds of 10 seconds or less in A4 size for thermal fax and 120 characters / second or more for thermal printer have become possible, and there is a further demand for higher sensitivity of the thermal recording material. Moreover, the thermal recording material is a label for POS system, a ticket,
As it has been applied to a wide range of fields such as image recording paper, heat resistance and storability of recorded images and blank portions against oils and fats, solvents or plasticizers have been required. However, since a conventional thermosensitive recording material uses a phenol-based coloring agent such as bisphenol A, there is a drawback that the background fog is caused by a solvent or the coloring material is discolored by oils and chemicals. Have Further, in JP-A-5-147357, 4,4'-
A heat-sensitive recording material using bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane is described, but a heat-sensitive recording material using such a color developing agent has improved recording image storability but low recording sensitivity. There is.

Various methods such as a method of providing a protective layer on the recording layer and a method of adding a storability improver to the recording layer have been proposed for the purpose of improving such defects, but each of them has new defects. However, there is a strong demand for further improvement because the effect is not always satisfactory.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal recording material which is excellent in recording sensitivity and storability of a recorded image with respect to a plasticizer and has less background fog.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have proposed a thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored leuco dye and a coloring agent.
The above problems can be achieved by using 4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane and 1,3-bis [α-methyl-α- (4'-hydroxyphenyl) ethyl] benzene in combination. This has led to the completion of the present invention.

[0007]

The thermosensitive recording medium using 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane as a coloring agent is excellent in oil resistance and plasticizer resistance of a color image, but has a drawback that recording sensitivity is low. was there. Conventionally,
Waxes having a melting point of 40 to 100 ° C. are used as a carrier (JP-A-48-19231), or a fatty acid amide and a petroleum wax are combined (JP-B-51).
No. 27599), it has been proposed to increase the sensitivity.

However, although these methods have some effect on the improvement of sensitivity,
In combination with 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane, there was a problem that the storage stability of the background, especially the background fogging easily caused by contact with humidity or a plasticizer.

Therefore, as a result of intensive studies on the improvement of sensitivity, the present inventors have found that 1,3-bis [α
-Methyl-α- (4'-hydroxyphenyl) ethyl]
It has been found that the combined use of benzene improves the recording sensitivity and the recording density without lowering the whiteness, and completed the present invention.

Thus, in the present invention, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane and 1,3-bis [α-methyl-α-
The compounding ratio of (4'-hydroxyphenyl) ethyl] benzene is not particularly limited, but it is 4,4 '.
In the range of about 1 to 200 parts by weight of 1,3-bis [α-methyl-α- (4'-hydroxyphenyl) ethyl] benzene per 100 parts by weight of -bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane. It is desirable to adjust.

Various types of colorless or pale leuco dyes contained in the heat-sensitive recording layer are known, and 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, 3,3-bis (2-phenylindol-3-yl) -6-dimethylaminophthalide, 3- (p-dimethyl) Aminophenyl) -3-
A phthalide dye such as (1-methylpyrrol-3-yl) -6-dimethylaminophthalide and 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3
-Diethylamino-6-methylfluorane, 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-methyl-N-benzylamino)
Fluorane, 3-diethylamino-7-diethylaminofluorane, 3- (N-ethyl-p-toluidino) -6
-Methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluorane, 3-diethylamino-6-methyl-7
-Anilinofluorane, 3-dimethylamino-6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-dipentylamino-6- Methyl-7-anilinofluorane,
3-diethylamino-7- (2-carbomethoxy-anilino) fluorane, 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane, 3-
(N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-6-
Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3
-Dibutylamino-7- (o-chloroanilino) fluorane, 3- (N-ethyl-N-cyclopentylamino)
-6-methyl-7-anilinofluorane, 3- [N-
(3-Ethoxypropyl) -N-methylamino] -6-
Methyl-7-anilinofluorane, 3- [N-ethyl-
N- (3-ethoxypropyl) amino] -6-methyl-
7-anilinofluorane, 3-diethylamino-7-
[M- (trifluoromethyl) anilino] fluorane,
3-diethylamino-7- (o-fluoroanilino) fluorane, 3-dibutylamino-7- (o-fluoroanilino) fluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- (N -Ethyl-N-p
-Tolylamino) -7-methylfluorane, 3- (N-
Ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3- (N-cyclopentyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3- (N- Fluorane dyes such as ethyl-Np-tolylamino) -6-methyl-7-anilinofluorane. Of course, the dyes are not limited to these dyes, and two or more dyes may be used in combination.

The present invention uses 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane as a color former and 1,3-bis [α-methyl-α-
The feature is that (4′-hydroxyphenyl) ethyl] benzene is used, but the following known colorants can be used in combination, for example, within a range that does not impair the effects of the present invention.

4,4'-dihydroxy-diphenylmethane, 4,4'-isopropylidene diphenol (bisphenol A), hydroquinone, 4,4'-cyclohexylidene bisphenol, 4,4 '-[1,4-phenylene bis] (1-methylethylidene)] bisphenol,
4,4 '-[1,3-phenylene bis (1-methylethylidene)] bisphenol, 4,4'-(1,3-dimethylbutylidene) bisphenol, 2,2-bis (4-
Hydroxyphenyl) -4-methyl-pentane, 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, bis (3-allyl-4) -Hydroxyphenyl) sulfone,
1,3-di [2- (4-hydroxyphenyl) -2-
Propyl] benzene, hydroquinone monobenzyl ether, methyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, 4
-Dimethyl hydroxyphthalate, 1,5-bis (4-hydroxyphenylthio) -3-oxa-pentane, (4
-Hydroxyphenylthio) acetic acid-2- (4-hydroxyphenylthio) ethyl ester, novolac type phenol resin, phenolic compound such as phenol polymer,
3-cyclohexyl-4-hydroxybenzoic acid, 3,5
-Dimethyl-4-hydroxybenzoic acid, 3,5-di-te
rt-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-methylbenzyl salicylic acid, 4- (2-P-methoxyphenoxyethoxy) salicylic acid, 4- (3-P
An aromatic carboxylic acid such as -tolylsulfonylpropyloxy) salicylic acid, and a phenolic compound or aromatic carboxylic acid thereof and a polyvalent metal such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin or nickel. Organic acidic substances such as salt. Of course, these colorants may be used in combination of two or more, if necessary.

The use ratio of the leuco dye and the coloring agent contained in the recording layer is not particularly limited, but is generally 0.5 to 1 part by weight of the leuco dye.
It is desirable to use about 50 parts by weight, preferably about 1 to 10 parts by weight of the color former.

In the present invention, a sensitizer may be added to the recording layer if necessary. Specific examples of the sensitizer in that case include, for example, stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide,
Ethylenebistearic acid amide, behenic acid amide, methylenebisstearic acid amide, N-methylolstearic acid amide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, benzyl p-benzyloxybenzoate, 1-hydroxy-2-naphthoate. Phenyl acid salt, dibenzyl oxalate, oxalate-di-p-methylbenzyl, oxalate-di-p-chlorobenzyl, 2-
Naphthyl benzyl ether, m-terphenyl, p-benzyl biphenyl, biphenyl-p-tolyl ether,
Di (p-methoxyphenoxyethyl) ether, 1,2
-Di (3-methylphenoxy) ethane, 1,2-di (4
-Methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ethane, 1,2-di (4-chlorophenoxy) ethane, 1,2-diphenoxyethane, 1- (4
-Methoxyphenoxy) -2- (2-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetotoluidide, p-acetophenetide, N-acetoacetyl-p- Toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene,
Examples include 4,4′-dihydroxydiphenyl sulfone, 1-isopropylphenyl-2-phenylethane and the like. The amount of these sensitizers used is not particularly limited, but it is generally desirable to adjust the amount within the range of about 5 to 500 parts by weight with respect to 100 parts by weight of the color developing agent.

Further, in order to suppress the background fog caused by heat, tetrakis (1,2,2,6,6-pentamethyl-4
It is desirable to use a hindered amine stabilizer such as -piperidinyl) -1,2,3,4-butanetetracarboxylate together. Further, as long as the effect of the present invention is not impaired, a preservative improving agent can be used in combination, if necessary, in order to further enhance the preservability of the recorded image. Specific examples of such storage improvers include 1,4-diglycidyloxybenzene, 4,4′-diglycidyloxydiphenyl sulfone, 4-benzyloxy-4 ′-(2-methyl-2,3-epoxy). Propyloxy) diphenyl sulfone, diglucidyl terephthalate, bisphenol A
Type epoxy compounds such as epoxy resin, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-te)
rt-butylphenol), 2,2'-ethylidene bis (4,6-di-tert-butylphenol), 4,
4'-thiobis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methyl-6-t
ert-butylphenol), 4,4'-butylidene bis (6-tert-butyl-m-cresol), 1,1,3
-Tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4'-thiobis ( 3-methylphenol),
4,4'-dihydroxy-3,3 ', 5,5'-tetrabromodiphenyl sulfone, 4,4'-dihydroxy-
3,3 ′, 5,5′-tetramethyldiphenyl sulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-)
Hindered phenol compounds such as 3,5-dichlorophenyl) propane and 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 1- [α-methyl-α- (4′-hydroxyphenyl) ethyl ] -4-
[Α ', α'-bis (4 "-hydroxyphenyl) ethyl] benzene, N, N'-di-2-naphthyl-p-phenylenediamine, 2,2'-methylenebis (4,6-di-tert- Butylphenyl) sodium phosphate and the like.

In order to prepare a coating liquid for a recording layer containing these substances, water is generally used as a dispersion medium, and a leuco dye, a coloring agent, and A coating solution can be obtained by dispersing and preparing a sensitizer or the like added as necessary together or separately. In such a coating solution, as an adhesive, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, arabic gum, polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt. , Ethylene / acrylic acid copolymer salt,
The styrene / acrylic acid copolymer salt, the styrene / butadiene copolymer emulsion and the like are adjusted in the range of 10 to 40% by weight, preferably 15 to 30% by weight of the total solid content.

It is also possible to use various pigments in combination in the coating liquid, for example, inorganic materials such as kaolin, clay, calcium carbonate, calcined clay, calcined kaolin, titanium oxide, diatomaceous earth, fine anhydrous silica and activated clay. Examples thereof include pigments, styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and organic pigments such as raw starch particles.

Further, in the coating solution, various auxiliaries such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate / sodium salt, alginate, fatty acid metal salt, and the like, benzophenone-based agents are used. , A triazole-based ultraviolet absorber, other defoaming agents, fluorescent dyes, coloring dyes and the like can be appropriately added.

In the present invention, the method for forming the heat-sensitive recording layer is not particularly limited, and the heat-sensitive recording layer can be formed according to a conventionally known and commonly used technique. For example, air knife coater, variber blade coater, pure blade coater, short dwell coater,
It can be formed by coating the coating solution on a support with a curtain coater or the like and drying. Also, there are no particular limitation on the coating amount, 2~12g / m ² in weight after drying, it is preferably adjusted in the range of 3 to 10 g / m ^2. As the support, paper, synthetic paper, plastic film or the like is appropriately selected and used.

If necessary, on the thermosensitive recording medium and /
Alternatively, by providing a resin layer on the back surface of the recording medium,
Furthermore, it is possible to enhance the storage stability of the recorded image. Further, an undercoat layer may be provided on the support to improve image quality and sensitivity, an adhesive label may be applied to the back surface of the recording material to form an adhesive label, or a magnetic layer may be provided on the back surface of the recording material to form a thermosensitive recording material. Various known techniques in the manufacturing field can be applied. Further, the image quality and the image density can be improved by performing a super calendering process after forming the recording layer.

[0022]

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. Unless otherwise specified, "part" and "%" in the examples are
"Part by weight" and "% by weight" are shown, respectively.

Example 1 Preparation of Solution A 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 5% aqueous solution of methylcellulose 5
Parts and 40 parts of water were pulverized with a sand mill until the average particle size became 1.5 μm.

Preparation of Solution B A composition consisting of 30 parts of 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane, 5 parts of a 5% aqueous solution of methylcellulose, and 80 parts of water having an average particle size of 1. It was pulverized until it became 0 μm or less.

Preparation of Solution C A composition consisting of 30 parts of 1,3-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 5 parts of a 5% aqueous solution of methylcellulose, and 80 parts of water was sand-milled. It was pulverized until the average particle diameter became 1.0 μm.

Preparation of liquid D: Acetoacetyl group-modified polyvinyl alcohol (trade name:
Z-200, Nippon Synthetic Chemical Industry Co., Ltd.) 8% aqueous solution 1000
Part, 30 parts of kaolin (trade name: Hydrin Z-7, manufactured by Chukyo Yushi Co., Ltd.), and 2 parts of 40% glyoxal were mixed and stirred to prepare a coating liquid for protective layer.

Formation of thermal recording medium 55 parts of A solution, 80 parts of B solution, 35 parts of C solution, 160 parts of 10% polyvinyl alcohol aqueous solution, and clay (trade name: H
G clay, manufactured by Huber Corporation) recording layer coating solution obtained by mixing and stirring 25 parts, as the coating amount after drying on one surface of woodfree paper of 45 g / m ² is 4g / m ² coating, drying To form a recording layer. Further, the liquid D was applied onto the recording layer so that the coating amount after drying was 3 g / m ² and dried to obtain a thermosensitive recording medium having a protective layer.

Example 2 Preparation of Solution E A composition consisting of 10 parts of 3-di (n-butylamino) -7- (o-chloroanilino) fluorane, 5 parts of a 5% aqueous solution of methylcellulose, and 40 parts of water was averaged on a sand mill. It was pulverized until the particle diameter became 1.5 μm.

Formation of Recording Medium A thermal recording medium was obtained in the same manner as in Example 1 except that 55 parts of E liquid was used in place of 55 parts of A liquid in the formation of the thermal recording medium of Example 1.

Example 3 Formation of Thermosensitive Recording Medium In the formation of the thermal recording medium of Example 1, synthetic paper (trade name: YUPO FPH-8 was used instead of the high-quality paper of 45 g / m ² ).
0, manufactured by Oji Yuka Co., Ltd.) was used to obtain a thermosensitive recording medium in the same manner as in Example 1.

Comparative Example 1 In the formation of the thermosensitive recording medium of Example 1, 80 parts of B liquid and C
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 115 parts of solution B was used instead of 35 parts of solution.

Comparative Example 2 In the formation of the recording material of Example 1, 80 parts of solution B and 3 parts of solution C were used.
Example 1 except that 115 parts of C liquid were used instead of 5 parts.
A thermosensitive recording medium was obtained in the same manner as described above.

Comparative Example 3 Preparation of Solution F A composition comprising 30 parts of 4-hydroxy-4′-isopropoxydiphenyl sulfone, 5 parts of a 5% aqueous solution of methylcellulose, and 80 parts of water was sand milled to have an average particle size of 1.0 μm. Crushed until Formation of Thermosensitive Recording Material In the formation of the recording material of Example 1, 80 parts of solution B and solution 3 of solution C
Example 1 except that 115 parts of F liquid was used instead of 5 parts.
A thermosensitive recording medium was obtained in the same manner as described above.

Comparative Example 4 Preparation of Liquid G A composition comprising 20 parts of oxalic acid di-p-methylbenzyl ester, 5 parts of a 5% aqueous solution of methyl cellulose, and 55 parts of water was sand-milled until the average particle size reached 1.5 μm. Crushed.

Formation of Thermal Recording Medium A thermal recording medium was obtained in the same manner as in Example 1 except that 35 parts of G liquid was used instead of 35 parts of C liquid in the formation of the recording medium of Example 1.

The following 7 evaluation tests were carried out on the thus obtained 7 kinds of thermosensitive recording media, and the obtained results are shown in Table 1.

[Recording density] Thermal recording evaluation machine (trade name: T
H-PMD, manufactured by Okura Electric Co., Ltd., applied voltage 24V,
Each of the thermosensitive recording materials was colored with an applied energy of 0.4 mJ / dot, and the coloring density of the obtained recorded image was measured in a visual mode with a Macbeth densitometer (RD-914 type, manufactured by Macbeth Co.).

[Plasticizer resistance] polypropylene pipe (4
A vinyl chloride wrap film (manufactured by Mitsui Toatsu Kagaku Co., Ltd.) was triple-wrapped on a 0 mmφ tube, and a thermosensitive recording material colored under the above conditions was sandwiched on the vinyl chloride wrap film so that the printed color surface was outside.
Further, a vinyl chloride wrap film was wound on it in three layers, and the print density after standing at 30 ° C. for 24 hours was measured by a Macbeth densitometer (RD-914 type, manufactured by Macbeth Co.) in a visual mode.

[Heat Resistance] As a background fogging acceleration test, a thermal recording material before printing was treated under a dry condition of 60 ° C. for 24 hours, and the degree of fogging was evaluated by a Macbeth densitometer (RD-
914 type, manufactured by Macbeth Co., Ltd.] in visual mode.

[Moisture resistance] The heat-sensitive recording material after the above-mentioned color development is 50
After processing for 24 hours under the conditions of ℃ and 95% RH, the degree of background fog and the degree of fading of the print are determined by Macbeth densitometer (RD-
914 type, manufactured by Macbeth Co., Ltd.] in visual mode.

[0041]

[Table 1]

[0042]

As is clear from the results shown in Table 1, each of the thermosensitive recording materials of the present invention was excellent in storability of recorded images, especially in heat and humidity resistance and plasticizer resistance, and also in recording sensitivity. It is a thing.

Claims (1)

[Claims] 1. A thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored leuco dye and a coloring agent, wherein 4,4′-bis (p-toluenesulfonylamino) is used as the coloring agent. A thermosensitive recording medium characterized by using carbonylamino) diphenylmethane and 1,3-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene.