JPH07266709A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material high in recording sensitivity and excellent in the chemical resistance of a recording image and the water resistance of a recording surface. CONSTITUTION:In a thermal recording material wherein a thermal recording layer containing a colorless or light-colored basic dye and a coupler is provided on a support, as the coupler, 4,4'-bis(p-toluenesulfonylaminocarbonylamino) diphenylmethane is used and an alkali salt of a water-soluble styrene/acrylic acid copolymer is used in the thermal recording layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording medium, and more specifically, it has good recording sensitivity.
The present invention relates to a heat-sensitive recording material having excellent chemical resistance of a recorded image and water resistance of a recording surface.

[0002]

2. Description of the Related Art Heretofore, a heat-sensitive recording material has been well known in which a color-developing image is obtained by bringing two color-forming substances into contact with each other by heat utilizing a color-developing reaction between a colorless or light-colored basic dye and a color-developing agent. ing. Such a thermal recording medium has advantages such as a compact recording apparatus, low cost, and easy maintenance, and is not only used as a recording medium for a facsimile, an automatic ticket vending machine, or a scientific measuring instrument, POS label, C
It is widely used as an output medium for various printers and plotters for AD and CRT medical images. As a result, chemical resistance and water resistance to water-based ink pens, oil-based ink pens, fluorescent pens, diazo developers or adhesives, glues, etc. have been demanded. Regarding water resistance, for example, when it is used outdoors, such as for handy terminals,
There is a problem that a recording surface is peeled off due to water droplets or the like on the recording surface and rubbing, and there is a strong demand for improvement of the water resistance of the recording layer.

Various water-soluble adhesives having improved water resistance have been proposed in the past, but they were insufficient in practical use (Japanese Patent Laid-Open Nos. 49-32646 and 49-363).
43, JP 50-30539 A, JP 5
2-145228, JP-A-55-159993, JP-A-57-189889). Further, various methods of providing an overcoat layer on the heat-sensitive recording layer have been proposed in order to improve chemical resistance and water resistance, but this is not a preferable method because it causes a decrease in sensitivity. On the other hand, when 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane is used as a colorant in the heat-sensitive recording layer, the thermal resistance of the heat-sensitive recording material is significantly improved without providing an overcoat layer. However, no effective means for improving the water resistance has been found.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, has good recording sensitivity, and has excellent chemical resistance of a recorded image and water resistance of a recording surface. To provide.

[0005]

In a thermosensitive recording medium in which a thermosensitive recording layer containing a colorless or light-colored basic dye and a color developing agent is provided on a support, 4,4'-bis ( It was found that the above object can be achieved by using p-toluenesulfonylaminocarbonylamino) diphenylmethane and further by using an alkali salt of a water-soluble styrene-acrylic acid copolymer in the heat-sensitive recording layer, and the present invention is completed. Came to.

[0006]

According to the present invention, as a color-developing agent in the heat-sensitive recording layer, 4,
4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane (hereinafter referred to as the present color developing agent) is used, and an alkali salt of a water-soluble styrene-acrylic acid copolymer is used as an adhesive component in the thermosensitive recording layer. The styrene-acrylic acid copolymer of the present invention is characterized by being used, and examples of the alkali salt of the styrene-acrylic acid copolymer include sodium salts, potassium salts, ammonium salts, and those in which these salts coexist, and both are used. It is water soluble. Among these alkali salts, ammonium salts are particularly preferably used. The molecular weight of the styrene-acrylic acid copolymer alkali salt is 30,000 to 250,000.
0 is preferable, and particularly 80,000 to 150,000 is preferable.

The amount of the alkali salt of styrene-acrylic acid copolymer to be added is based on the total solid content in the thermosensitive color developing layer.
The amount is preferably 5 to 30% by weight, more preferably 8 to 20% by weight. If it is less than this range, the water resistance is insufficient, and if it is more than this range, the sensitivity is significantly lowered.

As the basic dye contained in the heat-sensitive recording layer of the present invention, various known colorless or pale basic dyes can be used, and specific examples thereof include 3,3-bis (p-dimethylaminiphenyl). ) -6-Dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylamino-benzo [A] Fluoran, 3- (N-ethyl-N-p-tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-dibenzylamino Fluoran, 3,6-bis (diethylamino) fluorane-γ-anilinolactam, 3-cyclohexylamino-
6-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-
Chlorofluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3
-(N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-
6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane,
3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3-di (n-butyl)
Amino-7- (o-chlorophenylamino) fluorane, 3-diethylamino-7- (o-fluorophenylamino) fluorane, 3-di (n-butyl) amino-7
-(O-Fluorophenylamino) fluorane, 3-
(N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluorane, 3- (N -Ethyl-N-furfurylamino) -6-
Methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- (N-methyl-Nn-propylamino) -6-methyl-7-anilinofluorane, 3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl-]-4,5,6,7-tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl)
-1- (4-Pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3
-Bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide, 3-p- (p-dimethylaminoanilino) anilino-6 -Methyl-7-chlorofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthen-2'-ylamino] ] Phenyl} propane, 3,
6,11-tri (dimethylamino) fluorane and the like can be mentioned.

Of course, the present invention is not limited to these.
If necessary, two or more kinds can be used in combination. In particular, the color developing agent may be combined with 3-di (n-butyl) amino-6-methyl-7-anilinofluorane or 3-di (n-butyl) amino-7- (o-chloroanilino) fluorane. preferable.

The present color developing agent can be used in combination with conventionally known color developing agents within a range that does not impair the desired effect. Examples of such colorants include activated clay, attapulgite, colloidal silica, inorganic acidic substances such as aluminum silicate,
4,4′-isopropylidenediphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane,
4,4'-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-
Hydroxy-4'-isopropoxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, bis (4-hydroxyphenylthioethoxy) methane, 1,5-di (4-Hydroxyphenylthio) -3-
Oxapentane, bis (p-hydroxyphenyl) butyl acetate, methyl bis (p-hydroxyphenyl) acetate,
1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, di (4-hydroxy-3-methylphenyl) ) Sulfine and other phenolic compounds, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4- [3- (p-tolylsulfonyl) propyloxy] salicylic acid, 5- [p- (2-
aromatic carboxylic acids such as p-methoxyphenoxyethoxy) cumyl] salicylic acid, and salts of these aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin and nickel,
Further, organic acid substances such as antipyrine complex of zinc thiocyanate are exemplified.

The use ratio of the basic dye and the color developing agent is appropriately selected according to the type of the basic dye or the color developing agent to be used and is not particularly limited, but is generally basic. 1 to 50 parts by weight of coloring agent to 1 part by weight of dye,
Preferably, about 2 to 10 parts by weight of the coloring agent is used.

The coating liquid for the heat-sensitive recording layer containing the above-mentioned substances generally uses water as a dispersion medium, and the dye and the coloring agent are added together or separately by a stirring / grinding machine such as a ball mill, an attritor or a sand mill. It is prepared by dispersing.

In the present invention, the adhesive resin contained in the heat-sensitive recording layer is mainly composed of an alkali salt of styrene-acrylic acid copolymer. For the purpose of improving the fluidity of the paint, the heat-sensitive recording layer is used. It is also possible to jointly use a generally known adhesive resin. Examples thereof include polyvinyl alcohol, carboxy group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, cationic group-modified polyvinyl alcohol, sulfone group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, starch and its derivatives, gum arabic,
Gelatin, casein, methyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid salt, polyacrylic amide, styrene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, isopropylene-maleic anhydride copolymer A water-soluble resin such as a polymer can be used in combination.

In order not to impair the water resistance of the coating film, it is preferable to combine a water-soluble resin adhesive containing a reactive group such as an acetoacetyl group, a carboxyl group or an amide group with a crosslinking agent. Examples of the crosslinking agent include glyoxal, glutaraldehyde, polyhydric aldehyde compounds such as dialdehyde starch, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins, diglycidyl compounds such as glycerin diglycidyl ether, and dimethylol. A urea compound, an inorganic compound such as ammonium persulfate, ferric chloride, magnesium chloride, ammonium zirconia carbonate, or boric acid or borax can be used.

Various pigments can be used in combination in the heat-sensitive recording layer. For example, aluminum hydroxide, calcium carbonate, magnesium carbonate, talc, silica, diatomaceous earth,
Synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, inorganic fine powder such as surface-treated calcium carbonate and silica, and urea-formalin resin, styrene-methacrylic acid copolymer, polystyrene resin The organic resin fine powders such as the above can be used, but the combination with aluminum hydroxide is preferable for the present color developing agent.

If desired, various auxiliary agents can be added to the heat-sensitive recording layer. For example, dispersions of sodium dioctyl sulfonate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol sulfate, fatty acid metal salt, etc., Waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax, and auxiliary additive components conventionally used in heat-sensitive recording materials, such as dispersants, surfactants, antioxidants, and ultraviolet rays. Examples include inhibitors, coloring dyes, and coloring pigments.

If desired, a sensitizer may be used in combination with the heat-sensitive recording layer. Specific examples of the sensitizer include stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebisstearic acid amide, behenic acid amide, and methylenebisstearic acid. Amide, N-methylolstearic acid amide, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, 2-naphthylbenzyl ether, m-terphenyl, dibenzyl oxalate, oxalic acid-di -P-methylbenzyl, oxalic acid-di-p-chlorobenzyl, p-benzylbiphenyl, tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether, 1,2-di (3-methylphenoxy) ethane, 1, 2-di (4-methyl) Phenoxy)
Ethane, 1,2-di (4-methoxyphenoxy) ethane, 1,2-di (4-chlorophenoxy) ethane, 1,
2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (3-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetotoluidide, p-acetophenene Thidide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane and the like can be mentioned. The addition amount of these sensitizers is not particularly limited, but it is generally desirable to adjust the amount within a range not exceeding 4 parts by weight with respect to 1 part by weight of the color developing agent.

If desired, a storability improver may be added to further enhance the storage stability of the recorded image. Specific examples of such a storability improver include, for example, 2,
2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-ethylidenebis (4,6-di-tert-). Butylphenol), 4,4'-thiobis (3-methyl-6-tert)
-Butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methylphenol), 4,4'-butylidenebis (6-tert-butyl-m- Cresol, 1-
[Α-Methyl-α- (4′-hydroxyphenyl) ethyl] -4- [α ′, α′-bis (4 ″ -hydroxyphenyl) ethyl] benzene, 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'-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-3,
5-dichlorophenyl) propane, 2,2-bis (4-
Hydroxyl-3,5-dimethylphenyl) propane and other hindered phenol compounds, 1,4-diglycidyloxybenzene, 4,4'-diglycidyloxydiphenyl sulfone, diglycidyl terephthalate, cresol novolac type epoxy resin, phenol novolac type Epoxy resin, epoxy compound such as bisphenol A type epoxy resin, N, N′-di-2-naphthyl-p-phenylenediamine, 2,2′-methylenebis (4,6-di-t
ert-Butylphenyl) sodium phosphate, N, N '
-Di-2-naphthyl-p-phenylenediamine, 4,
4'-bis (ethyleneimine carbonylamino) diphenylmethane etc. are mentioned.

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, it can be formed by a method of coating and drying the coating liquid on a support by air knife coating, varibar blade coating, pure blade coating, short dwell coating, curtain coating, or the like. Further, the coating amount of the coating liquid is not particularly limited and is usually in the range of ² to 12 g / m ^{2 in} dry weight.
As the support, paper, synthetic paper, plastic film or the like is appropriately selected. If necessary, various known techniques in the field of heat-sensitive recording medium production may be added, such as providing an undercoat layer on the support or performing smoothing treatment such as super calendering after coating each layer. It is a thing.

Further, the heat-sensitive recording material of the present invention may be provided with a back layer on the surface opposite to the heat-sensitive recording layer, if necessary, to correct curl.

[0021]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples. In addition, in each Example, "part" and "%" show "weight part" and "weight%", respectively.

Example 1 Preparation of Liquid A (color-forming dye dispersion liquid) 40 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, styrene-maleic anhydride copolymer as a dispersant 20 parts of 20% aqueous solution of ammonium salt (trade name: Polymalon 1333, manufactured by Arakawa Chemical Co., Ltd.) and 40 parts of water were used to make an average particle diameter of 0.8 with an Ultra Viscomill (sand grinder manufactured by IMEX Co., Ltd.).
It was pulverized to have a particle size of μm to obtain a liquid A.

Preparation of liquid B (coloring agent, heat-fusible dispersion) 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane 20 parts, oxalic acid di-p
-A composition comprising 25 parts of methylbenzyl ester, 10 parts of a 20% aqueous solution of ammonium salt of a styrene-maleic anhydride copolymer (trade name: Polymalon 1333, manufactured by Arakawa Chemical Co., Ltd.) as a dispersant, and 45 parts of water, is Ultravisco. A mill (Sand grinder manufactured by IMEX Co., Ltd.) was pulverized to obtain an average particle diameter of 0.8 μm, and a liquid B was obtained.

Preparation of Liquid C (Pigment Dispersion) 60 parts of aluminum hydroxide (trade name: Hydilite H42, Showa Denko KK), polycarboxylic acid type polymer surfactant (trade name: Caribbon L400, Sanyo Kasei Co., Ltd.) ) 0.
A composition consisting of 1 part and 40 parts of water was dispersed with a high-speed stirrer to obtain a liquid C.

Formation of Recording Layer 25 parts of A liquid, 90 parts of B liquid, 40 parts of C liquid, 7 parts of 30% dispersion of zinc stearate, 20 parts of 30% dispersion of paraffin wax, and styrene-acrylic acid as an adhesive. Ammonium salt of copolymer (Brand name: Polymaron 1308
S, manufactured by Arakawa Chemical Co., Ltd.), a coating solution for heat-sensitive recording layer comprising 120 parts of a 15% aqueous solution so that the coating amount after drying is 6.0 g / m ^{2 on} one surface of a high-quality paper of 50 g / m ^2. After coating and drying to form a heat-sensitive recording layer, smoothing treatment was carried out with a super calender so that the Oken smoothness (J.TAPPI No. 5) was 2000 seconds to obtain a heat-sensitive recording material.

Example 2 Instead of an ammonium salt of a styrene-acrylic acid copolymer (trade name: Polymalon 1308S, manufactured by Arakawa Chemical Co., Ltd.) as an adhesive, a sodium salt of a styrene-acrylic acid copolymer (trade name: Polymalon 326). A thermal recording material was obtained in the same manner as in Example 1 except that 90 parts of a 20% aqueous solution of Arakawa Chemical Co., Ltd.) was used.

Comparative Example 1 Instead of an ammonium salt of a styrene-acrylic acid copolymer (trade name: Polymalon 1308S, manufactured by Arakawa Chemical Co., Ltd.) as an adhesive, an ammonium salt of a styrene-maleic anhydride copolymer (trade name: Polymalon). A thermal recording material was obtained in the same manner as in Example 1 except that 45 parts of a 40% aqueous solution of 372, manufactured by Arakawa Chemical Co., Ltd.) was used.

Comparative Example 2 A styrene-butadiene copolymer emulsion (trade name: L1537, manufactured by Asahi Kasei Co., Ltd.) was used as an adhesive instead of an ammonium salt of a styrene-acrylic acid copolymer (trade name: Polymalon 1308S, manufactured by Arakawa Chemical Co., Ltd.). , Concentration 50%)
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 36 parts were used.

Comparative Example 3 Instead of an ammonium salt of a styrene-acrylic acid copolymer (trade name: Polymalon 1308S, manufactured by Arakawa Chemical Co., Ltd.) as an adhesive, an ammonium salt of polyacrylic acid (trade name: Polymarlon 1316, Arakawa Chemical Co., Ltd.) was used. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 120 parts of a 15% aqueous solution of (produced) was used.

Comparative Example 4 Example 1 was repeated, except that 4-hydroxy-4'-isopropoxydiphenylsulfone was used in place of 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane in the preparation of solution B. A thermosensitive recording medium was obtained in the same manner as described above.

The thermal recording materials obtained in the respective examples and comparative examples were evaluated as follows, and the results are shown in Table 1. (1) Recording sensitivity High-speed facsimile manufactured by NEC: Nefax 23, standard chart No. Print using 2,
The color density of the obtained recorded image was measured with a Macbeth densitometer RD-91.
It was measured with a 4 type and set to a value representative of the recording sensitivity of the thermosensitive recording medium.

(2) Resistance to fluorescent pen, magic pen, diazo developer In the case of a fluorescent pen and a magic pen, writing is done normally on the surface of the thermosensitive recording medium, and with respect to resistance to diazo developer, diazo developer is used. After contacting the surface of the recording material with the high-quality paper moistened with, fog in the uncolored portion (background) was visually judged and evaluated according to the following criteria.

◯: No problem in practical use. Δ: Some problem in practical use. X: Not practical

(3) Plasticizer resistance Vinyl chloride wrap film (trade name: KMA-W, manufactured by Mitsui Toatsu Chemicals, Inc.) on a polypropylene pipe (40 mmφ pipe)
Is wound in three layers, the heat-sensitive recording material on which the above-mentioned color is printed is placed on top of it, and a vinyl chloride wrap film is further wound on it three times and left at 40 ° C for 24 hours, after which the color of the heat-sensitive recording material is developed. The fading of the part was evaluated by the same criteria as in (2) above.

(4) Water resistance After dropping one water drop on the surface of the thermosensitive recording medium, the degree of peeling of the recording surface was visually judged by rubbing 50 times with a finger and evaluated according to the following criteria. <Water resistance evaluation> O: Almost no peeling of the recording surface. Δ: The recording surface is slightly peeled off. X: The recording surface is often peeled off.

[0036]

[Table 1]

[0037]

As is clear from the results of Table 1, the thermosensitive recording medium of the present invention had good recording sensitivity and excellent chemical resistance of the recorded image and water resistance of the recording surface.

Claims (1)

[Claims] 1. A thermosensitive recording medium comprising a support and a thermosensitive recording layer containing a colorless or light-colored basic dye and a color developing agent, wherein 4,4'-bis (p-toluenesulfonyl) is used as the color developing agent. A heat-sensitive recording material characterized by using aminocarbonylamino) diphenylmethane and further containing a water-soluble alkali salt of a styrene-acrylic acid copolymer in the heat-sensitive recording layer.