JPH02286287A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain stable recording aptitude not affected by a change of external environment by containing an alumina sol in at least one of the respective layers constituting a recording material. CONSTITUTION:An alumina sol is contained in at least one of the thermal recording layer and support layer constituting a recording material as well as the protective layer, intermediate layer and support rear layer provided on the recording material if necessary but it is especially effective to contain the alumina sol in the support rear surface. The alumina sol is a high purity ultrafine particle sol prepared by using a distilled purified product of an organoaluminum compound as a raw material and a colloid solution of boehmite type alumina using water or alcohol as a dispersion medium is used and the use amount of said sol is 0.1 - 5g/m<2>, pref., 0.2 - 2g/m<2>. By this method, stable recording not affected by a change of external environment from low humidity to high humidity and not accompanied by a fog or blocking phenomenon even in high speed recording is possible.

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'' A thermosensitive recording material utilizes a coloring reaction between a colorless or light-colored basic dye and an organic or inorganic coloring agent to obtain a recorded image by bringing the two light-colored substances into contact with each other using heat. well 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's ability to pass through 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 substances is used to increase the conductivity,
Although the conductivity can be increased to some extent, there are problems such as unnecessary color development (fogging) on the recording medium and blocking between the recording bodies under high humidity conditions.

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 alumina sol among various conductive substances, and when it is incorporated into a heat-sensitive recording material, it is possible to change the temperature from low humidity to high humidity. It is possible to obtain a thermal recording medium that is unaffected by changes in the external environment, allows stable recording without fogging or blocking phenomena even during high-speed recording, has high whiteness, and has extremely high commercial value. The present invention was completed based on the discovery that the present invention is possible.

"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 alumina sol. It is.

As described above, the heat-sensitive recording material of the present invention contains alumina sol in at least one of the layers constituting the recording material. As an example of the alumina sol, a distilled product of an organic aluminum compound is used as a raw material. A colloidal liquid of boehmite-type alumina with water or alcohol as a dispersant is used.

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 alumina sol,
It is particularly effective to contain the alumina sol in the back layer of the support, and especially when a film or synthetic paper is used as the support, it is desirable to contain alumina sol in the back layer of the support.

The amount of alumina sol 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 to 5. g/rd or so, more preferably 0.2
~2 g/rrT is contained.

In the present invention, there are various known colorless or light-colored basic dyes constituting the recording layer of the heat-sensitive recording material.
For example, the following are exemplified.

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-ethylcarbazole-
3-yl)-6-dimethylaminophthalide, 3,3-bis(2-phenylindol-3-yl)-6-dimethylaminophthalide, 3-P-dimethylaminophenyl-
Triallylmethane dyes such as 3-(1-methylpyrrol-3-yl)-6-dimethylaminophthalide, 4.4'
-Bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leucoolamine, N-2,4
, 5-) diphenylmethane dyes such as dichlorophenyl leuco auramine, benzoyl leucomethylene blue,
Thiazine dyes such as P-nitrobenzoylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-
Ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-nat(6'-methoxyhenzo)
spiro dyes such as spiropyran, 3-propyl-spiro-dibenzobilane, rhodamine B-anilinolactam,
Lactam dyes such as rhodamine (p-nitroanilino)lactam and rhodamine (0-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-
) Luidino)-7-methylfluorane, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamine-7-sibenzylaminofluoran Oran, 3-diethylamino-7-N-methyl-N-benzylaminofluorane, 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-1
-luidino)-6-methyl-7-(p-toluidino)fluoran, 3-diethylamino-6-methyl-7-phenylaminofluoran, 3-dibutylamino-6-methyl-7-phenylaminofluoran, 3- Diethylamino-7-(2-carbomethoxyphenylamino)fluoran, 3-(N-cyclohexyl-N-methylamine)
-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-dibutylamino-
7-(o-chlorophenylamino)fluorane, 3-pyrrolidino-6-methyl-7-T)-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-N-n-hexyl)amino-6-
Methyltwophenylaminofluorane, 3-(N-ethyl-N-β-ethylhexyl)amino-6-methyl-
7-phenylaminofluorane, 3-(N-ethyl-N
-tetrahydrofurfuryl)amino-6-methyl-7-
Fluoran dyes such as phenylaminofluoran and 3-(N-ethyl-N-cyclopentyl)amino-6-methyl-7-phenylaminofluoran. Of course, the dyes are not limited to these dyes, and two or more types of dyes can be used in combination.

Furthermore, various compounds are known as coloring agents used in combination with the above-mentioned basic dyes, for example, the following are exemplified.

4-tert-butylphenol, α-naphthol, β
-naphthol, 4-acetylphenol, 4tert
-octylphenol, 4.4'-5ec-butylidene diphenol, 4-phenylphenol, 4.4'-dihydroxy-diphenylmethane, hydroquinone, 4,
4'-isopropylidene diphenol, 44'-cyclohexylidene diphenol, 4,4'-(1,3-dimethylbutylidene)bisphenol, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis(6 -tert-butyl-3-methylphenol), 4
゜4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-methoxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-3'4'tri Methylene diphenyl sulfone, 4-hydroxy-3'4'-tetramethylene diphenyl sulfone, 3,4-dihydroxy-4'-methyldiphenyl sulfone, bis-(3-allyl-4-hydroxyphenyl) sulfone, 1. 3-',; (2-(
4-hydroxyphenyl)-2-propyl]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, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, 4-hydroxybenzoic acid-5
ec-butyl, pentyl 4-hydroxybenzoate, 4-
Phenyl hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, 4-hydroxybenzoate 6fi p- Phenolic compounds such as chlorobenzyl, p-methoxybenzyl 4-hydroxybenzoate, novolac type phenolic resin, phenol polymer, benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3sec
-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-methyl benzyl) salicylic acid, 3-phenyl-5-(α, α-dimethylbenzyl) salicylic acid, 3,
Aromatic carboxylic acids such as 5-di-α-methylbenzyl salicylic acid, and combinations of these phenolic compounds and aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel. salt etc.

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 selected appropriately depending on the type of basic dye and coloring agent used, and is not particularly limited, but in general, the ratio is based on 100 parts by weight of the basic dye. 100 to 700 parts by weight, preferably 150 to 4 parts by weight
About 0.00 parts by weight of 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, diisobutylene/maleic anhydride copolymer salt, styrene/maleic anhydride copolymer salt as binders. , ethylene/acrylic acid copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulsion, urea resin, melamine resin, amide resin, etc. in a total solid content of 2 to 40% by weight, preferably 5%. ~25% by weight.

Furthermore, various auxiliary agents can be added to the coating liquid.
Examples include dispersants such as sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, other antifoaming agents, fluorescent dyes, and colored dyes.

Furthermore, inorganic pigments such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, and activated clay may be added to improve the adhesion of residue to the recording head. In addition, dispersions or emulsions of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, etc. can be added to prevent sticking from contact with recording equipment or recording heads. .

Furthermore, fatty acid amides such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, valmitic acid amide, and coconut fatty acid amide, 2,
2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-butylidenebis(6-te
rt-3-methylphenol), 1,1,3-tris(
Hindered phenols such as 2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,2-
Bis(phenoxy)ethane, 1.2-bis(4-methylphenoxy)ethane, 1.2-bis(3-methylphenoxy)ethane, 1-phenoxy-2-(4-methylphenoxy)ethane, 2-naphtholbenzyl ether, 1
．． Ethers such as 4-dimethoxynaphthalene and 1,4-jethoxynaphthalene, esters such as dibutyl terephthalate, dibenzyl terephthalate, and 1-hydroxy-2-naphthoic acid phenyl ester, 2-(2'-hydroxy-5'- methylphenyl)benzotriazole,
Ultraviolet absorbers such as 2-hydroxy-4-benzyloxybenzophenone, p-benzyl-biphenyl, and various known thermofusible substances can also be used in combination as sensitizers.

Furthermore, ordinary conductive substances can 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 can be formed according to conventionally well-known and commonly used techniques. For example, in a method of applying a coating liquid for a heat-sensitive recording layer to a support, an appropriate coating device such as an air knife coater, blade coater, bar coater, gravure coater, curtain coater, etc. is used.

Furthermore, the amount of coating liquid applied is not particularly limited, and is usually 2 to 12 g/%, preferably 3 to 1% by dry weight.
It is adjusted within a range of about 0 g/rrr.

Paper, plastic film, synthetic paper, etc. are used as the support.

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 alumina sol. If necessary, suitable auxiliary agents such as inorganic pigments, dyes, and waterproofing agents may be added to the coating liquid.

"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 "part" and "%j" in the examples indicate "part by weight" and "% by weight", respectively, unless otherwise specified.

Example 1 ■ Preparation of liquid A 3-(N-ethyl-N-isoamyl)amino-6-methyl-7-phenylaminofluorane 10 parts 1.2-bis(phenoxy)ethane 20 parts Methyl cellulose 5% aqueous solution 20 parts water
40 parts of this composition was ground in a sand mill until the average particle size was 2 μm.

■ Preparation of Solution B 4.4'-Isopropylidene diphenol 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 2 μm.

(2) Formation of recording layer 90 parts of liquid A, 90 parts of liquid B, silicon oxide pigment (trade name: Mizukasil P-527, average particle size: I.

8 (tm, oil absorption 1: 180cc/100g, manufactured by Mizusawa Chemical Co., Ltd.) 30 parts, 20% oxidized starch aqueous solution 150 parts, water 28
These parts were mixed and stirred to prepare a coating liquid. The resulting coating liquid was coated on synthetic paper (
After drying, the mixture was coated on a product (trade name: Yubo FPG, manufactured by Oji Yuka Synthetic Paper Co., Ltd.) at a coating weight of 5 g/M, and then subjected to a super calender to obtain a heat-sensitive recording material.

■ Formation of back layer Alumina sol (Product name: Alumina clear sol.

(Manufactured by Yoken Fine Chemical Co., Ltd.) 160 parts of a 5% aqueous solution Polyvinyl alcohol 14 parts of a 15% aqueous solution A coating solution obtained by mixing and stirring this composition was applied to the back surface of the support of the heat-sensitive recording material so that the coating amount after drying was 1°. The heat-sensitive recording material of the present invention was obtained by coating and drying the coating to a concentration of 0 g/rd.

Comparative Examples 1-2 In forming the back layer, a 5% aqueous solution of alumina sol 16
Two types of heat-sensitive recording materials were obtained in the same manner as in Example 1, except that 8 parts of tin oxide (Comparative Example 1) and 8 parts of anionic polymer conductive agent (Comparative Example 2) were used instead of 0 parts. Ta.

The following evaluation tests were conducted on the three 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 at room temperature (20°C, 260%).
RH) and low humidity conditions (20°C, 920% RH) using a terra ohmmeter (Model, VE-3 manufactured by Hokawaguchi Electric Co., Ltd.).

[Record aptitude]

Practical high-speed facsimile (Panafax tIF60.
(manufactured by Matsushita Electric Transmission Co., Ltd.) under normal temperature conditions (20°C, 260°C RH) and low humidity conditions (20'C, 20% RH) to evaluate paper feeding and ejecting suitability, and evaluate the recording density of the recorded image using Macbeth. It was measured with a densitometer (RD-914, manufactured by Macbeth).

[Paper feeding and paper ejection suitability]

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.

Line: ``Mu M''``Effect'' As is clear from the results in Table 1, all of the heat-sensitive recording materials of the present invention were unaffected by changes in the external environment and had stable recording suitability.

Claims (1)

[Claims] In a heat-sensitive 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, at least one of the layers constituting the recording layer. A heat-sensitive recording material characterized by containing alumina sol.