JPS63176178A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material on which stable recording is possible without any influence of changes in external environment from low humidity to high humidity, by making at least one layer among respective ones comprising the recording material contain conductive mica. CONSTITUTION:Conductive mica, for instance, prepared by coating the surface of pulverized powder of mica slice with ultrafine thin oxide and antimony oxide particles is preferably used as conductive mica. The conductive mica is made to be contained in, at least, one layer among various layers such as a thermal recording layer and a base material layer basically comprising a recording material, and a protective layer, an intermediate layer, a base material rear face layer, etc., established further if necessary. When a film or a synthetic paper is used especially as the base material, the conductive mica is made to be contained in the base material rear face layer. The use of the conductive mica is suitablly controlled according to the kind of the base material, the constitutional content of the recording layer, and further the state or the like of layers to be contained. 0.1-5g/m<2> level is generally and 0.2-2g/m<2> level thereof is more preferably contained.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a heat-sensitive recording medium, and in particular a heat-sensitive recording medium that can always record stably without being affected by the external environment such as humidity conditions or recording conditions such as recording speed. It is related to recording bodies.

``Prior art'' Thermal recording materials that utilize a color reaction between a colorless or light-colored basic dye and an organic or inorganic coloring agent to obtain a recorded image by bringing a recoloring substance into contact with heat are well known. Are known.

Such heat-sensitive recording media are relatively inexpensive, and the recording devices are compact and relatively easy to maintain, so they are used not only as recording media for facsimiles and various computers, but also in a wide range of fields.

With the expansion of usage, thermal recording media are recorded under various conditions such as external environments, but it is necessary to have excellent recording aptitude so that stable recorded images can always be obtained. Various improvement proposals have been made.

For example, when recording under low humidity, frictional electrification between the recording device and the recording paper may reduce the paper passing ability of the recording paper.
Metal oxides, metal halides, polymer electrolytes,
A method of treating a recording medium with various conductive substances such as surfactants and hygroscopic substances is disclosed in JP-A-57-148687 and JP-A-5.
This method has been proposed in Japanese Patent Application Laid-Open No. 7-156292, Japanese Patent Application Laid-open No. 57-170794, Japanese Patent Application Laid-Open No. 57-199687, and considerable improvement effects have been obtained.

``Problems to be solved by the invention'' However, in recent years, in order to obtain thermal recording media with excellent resolution, the use of films and synthetic papers as supports has increased. If used,
Even if the various conductive substances mentioned above are used, satisfactory results are not necessarily obtained, and there is still room for improvement.

That is, compared to using ordinary paper as a support,
When a film or synthetic paper is used, frictional electrification is significant, especially under low humidity conditions, and the above-mentioned conductive materials cannot provide a sufficient antistatic effect. Therefore, it is conceivable to use a metal-based conductive agent with high conductivity, but the metal-based conductive agent is significantly colored, resulting in a decrease in the commercial value of the resulting heat-sensitive recording material. In addition, if a large amount of the above-mentioned conductive 'JjyJ' material is used in order to increase the conductivity, although the conductivity can be increased to a certain extent, it may cause unnecessary coloring on the recording material (causing the turnip phenomenon or under high humidity conditions). However, there are problems such as blocking between recording media.

In view of the current situation, the inventors of the present invention have conducted intensive research to resolve the above-mentioned difficulties, and have selected conductive mica from among various conductive substances, and by incorporating it into a heat-sensitive recording medium, it has been found that Thermal recording is unaffected by changes in the external environment, even at high humidity levels, and is capable of stable recording without capri or profking phenomena even at high speeds.Moreover, the recording body has high whiteness, making it a thermal recording with extremely high commercial value. The present invention was completed based on the discovery that the present invention can be obtained.

"Means for Solving the Problem" The present invention provides colorless or light-colored basic dye on a support,
A thermosensitive recording material provided with a recording layer containing a coloring agent that causes the basic dye to develop a specific color under heat, characterized in that at least one of the layers constituting the recording material contains conductive mica. It is a record.

"Function" As described above, the heat-sensitive recording material of the present invention contains conductive mica in at least one of the layers constituting the recording material. Conductive mica coated with superimimetic particles of tin oxide and antimony oxide is preferably used.

Such conductive mica can be prepared, for example, by adding antimony chloride, tin chloride alcohol, acetone,
Alternatively, it can be produced by adding an aqueous hydrochloric acid solution and hydrolyzing antimony chloride and tin chloride on the surface of mica powder.

In the heat-sensitive recording material of the present invention, at least one of the heat-sensitive recording layer, the support layer, which basically constitutes the recording material, and various layers such as a protective layer, an intermediate layer, and a back layer of the support provided as necessary. One of them is that it contains conductive mica,
It is particularly effective to incorporate the conductive mica into the back layer of the support. Particularly when a film or synthetic paper is used as the support, it is desirable to include conductive mica in the back layer of the support.

The amount of conductive mica to be used is appropriately adjusted depending on the type of support, the composition of the recording layer, and the situation of the layer in which it is contained, and is not particularly limited, but is generally 0.1 ~5 g/rd or so, more preferably 0
．． It is made to contain about 2 to 2 g/rd.

In the present invention, the basic dye contained in one recording layer includes various known colorless or light-colored basic dyes, such as 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-dimethylindole-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-(l-methylpyrrol-3-yl)-6-
triallylmethane dyes such as dimethylaminophthalide,
4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leucoolamine, N
- diphenylmethane dyes such as 2,4,5-trichlorophenylleucoolamine, thiazine dyes such as benzoylleucomethylene blue and p-nitrobenzoylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-
Spiro dyes such as dinaphthopyran, 3-methyl-naphtho-(6'-methoxybenzo)spiropyran, 3-propyl-spiro-dibenzobilane, rhodamine-B anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine (0- Lactam dyes such as chloroanilino)lactam, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-methoxyfluoran,
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-? -N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-N-methyl-N-benzylamino Fluoran, 3-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 3-(N-ethyl-p-)luidino)-6-
Methyl-7-phenylaminofluorane, 3-(N-ethyl-p-toluidino)-6-methyl-7-(p-toluidino)fluorane, 3-diethylamino-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)fluoran, 3-dibutylamino-7-(o-chlorophenylamino)fluoran, 3-
Pyrrolidino-6-methyl-7-p-butylphenylaminofluorane, 3-diethylamino-7-(o-fluorophenylamino)fluorane, 3-dibutylamino-
7-(o-fluorophenylamino)fluorane, 3-
(N-methyl-Nn-amyl)amino-6-methyl-
7-phenylaminofluorane, 3-(N-ethyl-N
-n-amyl)amino-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-N-iso-amyl)amino-6-methyl-7-phenylaminofluorane, 3-(N-methyl -N-n-hexyl)amino-6-
Methyl-7-phenylaminofluorane, 3-(N-ethyl-N-n-hexyl)amino-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-N-β)
Examples include fluoran dyes such as -ethylhexyl)amino-6-methyl-7-phenylaminofluoran. In addition, two or more types of these basic dyes can be used in combination as necessary.

Examples of the coloring agent include inorganic or organic acidic substances that develop color upon contact with the basic dye, such as 4-
tert-butylphenol, α-naphthol, β-naphthol, 4-acetylphenol, 4-phenylphenol, hydroquinone, 4.4'-isopropylidenediphenol (bisphenol A), 2.2'-methylenebis(4-chlor phenol), 4.4'-cyclohexylidene diphenol, 1.3-di(2-(4-hydroxyphenyl)-2-propyl]-benzene, 4.4
'-dihydroxydiphenyl sulfide, bis-(3
-allyl-4-hydroxyphenyl)-sulfone, 4-
Hydroxyphenyl-4'-is.

-Propyloxyphenylsulfone, hydroquinone monobenzyl ether, 4-hydroxybenzophenone, 2
, 4-dihydroxybenzophenone, 2.4.4'-)
Rihydroxybenzophenone, 2.2', 4.4'-tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, 4- 5ec-butyl hydroxybenzoate, pentyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, phenylpropyl 4-hydroxybenzoate , 4
-Phenethyl hydroxybenzoate, p-chlorobenzyl 4-hydroxybenzoate, 4-hydroxybenzoic acid-
p-methoxybenzyl, novolank type phenolic resin,
Phenolic compounds such as phenol polymers, benzoic acid,
p-tert-butylbenzoic acid, trichlorobenzoic acid,
Telephthal! L 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-benzylsalicylic acid, 3-(α
-methylbenzyl)salicylic acid, 3-chloro-5-(α
-methylbenzyl)salicylic acid, 3,5-diter
t-Butylsalicylic acid, 3-phenyl-5-(α, α-
Aromatic carboxylic acids such as dimethylbenzyl) salicylic acid, 3,5-di-α-methylbenzyl salicylic acid, and these phenolic compounds, aromatic carboxylic acids such as zinc, magnesium, aluminum, calcium, titanium,
Examples include organic acidic substances such as salts with polyvalent metals such as manganese, tin, and nickel.

Note that, of course, two or more of these coloring agents can be used in combination as necessary.

The ratio of the basic dye and coloring agent to be used is appropriately selected depending on the type of basic dye and coloring agent used, and is not particularly limited, but in general, the ratio is based on 1 part by weight of the basic dye. About 1 to 20 parts by weight, preferably about 2 to 10 parts by weight, of the coloring agent is used.

Coating liquids containing these substances generally use water as a dispersion medium,
It is prepared by dispersing the dye and coloring agent together or separately using a stirring/pulverizing machine such as a ball mill, attritor, or sand mill.

Coating liquids usually contain starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, diisobutylene/maleic anhydride copolymer salt, styrene, etc. as binders. Maleic anhydride copolymer salt, ethylene/acrylic acid copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulsion,
Urea resin, melamine resin, amide resin, etc. have a total solid content of 2
-40% by weight, preferably 5-25% by weight.

Furthermore, various auxiliaries can be added to the coating liquid as necessary, such as sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, etc. Dispersants, UV absorbers such as benzophenone,
Other antifoaming agents, fluorescent dyes, coloring dyes, etc. may be added as appropriate.

In addition, waxes such as zinc stearate, galcium stearate, polyethylene wax, carnauba wax, halaffin wax, and ester wax, stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide, etc. fatty acid amide [,2,2'-methylenebis(4-
Methyl-5-tert-butylphenol>, i, 1.
3-tris(2-methyl-4-hydroxy-5-ter
Hindered phenols such as t-butylphenyl)butane, 2-(2'-hydroxy-5'-methylphenyl)
UV absorbers such as benzotriazole, 2-hydroxy-4-benzyloxybenzophenone, 1,2-di(3
-methylphenoxy)ethane, 1,2-diphenoxyethane, 1-phenoxy-2-(4-methylphenoxy)
Ethane, dimethyl terephthalate, dibutyl terephthalate, dibenzyl terephthalate,
Esters such as p-benzyl-biphenyl, 1,4-dimethoxynaphthalene, 1,4-jethoxynaphthalene, and 1-hydroxynaphthoic acid phenyl ester, as well as various known thermofusible substances, kaolin, clay, talc,
Inorganic pigments such as calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, and activated clay can also be added. Furthermore, ordinary conductive substances may be added within a range that does not impair the desired effects of the present invention.

In the heat-sensitive recording material of the present invention, the method for forming the recording layer is not particularly limited, and may be formed, for example, by a method of applying and drying a coating liquid by air knife coating, blade coating, or the like. Furthermore, the amount of coating liquid to be applied is not particularly limited, and is usually 2 to 12 g/m in terms of dry weight, preferably 3 to 10 g/r+(
It is prepared in a range of degrees.

Note that an overcoat layer can be provided on the recording layer for the purpose of protecting the recording layer, and a protective layer can also be provided on the back side of the support if necessary. Furthermore, various known techniques in the field of heat-sensitive recording material manufacturing can be added as necessary, such as providing an intermediate undercoating layer on the support, applying an adhesive treatment to the back surface of the recording material, and processing it into an adhesive label. .

In the heat-sensitive recording material of the present invention, at least one of the above-mentioned layers constituting the recording material contains conductive mica, and a coating liquid obtained by mixing conductive mica with a suitable binder is applied. A layer may be formed by covering the coating liquid, and appropriate auxiliary agents such as inorganic pigments, dyes, and waterproofing agents may be added to the coating liquid as necessary.

"Example" The present invention will be described in more detail with reference to Examples below, but it is of course not limited to these.

Note that "parts" and "%" in the examples indicate "parts by weight" and "% by weight", respectively, unless otherwise specified.

Example 1 ■ Preparation of liquid A 3-(N-ethyl-N-iso-amylamino)-6
-Methyl-7-phenylaminofluorane 10 parts Dibenzyl terephthalate 20 parts Methylcellulose 5% aqueous solution 20 parts Water
40 parts of this composition was ground in a sand mill until the average particle size was 3 μm.

■ Preparation of B solution 4. 4'-isopropylidenediphenol 30 parts Methyl cellulose 5% aqueous solution 40 parts water
20 parts of this composition was ground in a sand mill until the average particle size was 3 μm.

■ Formation of recording layer 90 parts of liquid A, 90 parts of liquid B, silicon oxide pigment (trade name: Mizukashiru P-527. Average particle size: 1°8 μm, oil absorption fi
t: 180cc/100g, manufactured by Mizusawa Chemical Co., Ltd.) 30
150 parts of a 20% oxidized starch aqueous solution and 28 parts of water were mixed;
The mixture was stirred to form a coating liquid. The obtained coating liquid was applied onto synthetic paper (trade name: Yubo FPG, manufactured by Oji Yuka Synthetic Paper Co., Ltd.) so that the coating amount after drying was 5 g/d, and after drying, it was applied with a super calender. A thermosensitive recording medium was obtained.

■ Formation of back layer Conductive mica (product name: MEC-500, manufactured by Teikoku Kako Co., Ltd.) 8 parts polyvinyl alcohol 15% aqueous solution 14 parts Water solution
Mix 10 parts of this composition;
The coating solution obtained by stirring was applied and dried on the back side of the support of a pre-glazed thermosensitive recording material so that the coated amount after drying was 2.5 g/rrr to obtain a thermosensitive recording material of the present invention.

Example 2 In forming the back layer, conductive mica (trade name: MEC
A thermosensitive recording material was obtained in the same manner as in Example 1, except that conductive mica (trade name: MEC-300, manufactured by Teikoku Kako Co., Ltd.) was used instead of MEC-500, manufactured by Teikoku Kako Co., Ltd.).

Comparative Examples 1 and 2 In forming the back layer, conductive mica (trade name: ME
A thermosensitive recording material was obtained in the same manner as in Example 1, except that tin oxide (Comparative Example 1) and anionic polymer conductive agent (Comparative Example 2) were used instead of C-500 (manufactured by Teikoku Kako Co., Ltd.). Ta.

The following evaluation tests were conducted on the four types of heat-sensitive recording bodies thus obtained, and the results are listed in Table 1.

[Measurement of surface resistance]

The surface resistance of the back layer of the recording medium was measured using a terra ohmmeter (Model, VB-30, manufactured by Kawaguchi Electric Co., Ltd.) under normal temperature conditions and low humidity conditions, and the results are shown in Table 1.

[Record aptitude]

Recording was performed using a practical high-speed facsimile (IIIFAX-700, manufactured by Hitachi) under room temperature and low humidity conditions to evaluate paper feeding and ejection suitability, and the recording density of the obtained recorded image was determined as Macbeth density g4.
(RD-10OR, manufactured by Macbeth), and the results are listed in Table 1. The evaluation criteria for paper feeding and paper ejection suitability were as follows.

O: No paper feeding/ejecting problems due to frictional charging.

×: The recording medium stuck to the facsimile machine due to frictional charging, causing a paper jam problem.

Table 1 v! ;:Komen Kubod beef...20℃, 60%, Fudehori Yoshii beef...20℃, 20% "Efficacy" As is clear from the results in Table 1, the thermal record of the present invention Both bodies were unaffected by changes in the external environment and had stable aptitude for recording.

Claims (4)

[Claims] (1) In a thermal recording material in which a recording layer containing a colorless or light-colored basic dye and a coloring agent that causes the basic dye to develop color when heated is provided on a support, each layer constituting the recording material A heat-sensitive recording material characterized in that at least one of the materials contains conductive mica. (2) The heat-sensitive recording material according to claim (1), wherein the conductive mica is a conductive mica whose surface is coated with ultrafine particles of tin oxide and antimony oxide. (3) The heat-sensitive recording material according to claim (1), wherein conductive mica is contained in the back layer of the support. (4) The heat-sensitive recording material according to claim (3), wherein the support is a film or synthetic paper.