JP2796155B2 - Thermal recording paper - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a thermosensitive recording paper, and more particularly to a thermosensitive recording paper excellent in stacking property when recording by a recording device such as a printer or a facsimile.

`` Prior art '' Conventionally, heat-sensitive recording paper which uses a reaction between a colorless or light-colored basic dye and an organic or inorganic colorant to contact a recording material by heat to obtain a recorded image is well-known. Are known. Such thermosensitive recording paper is relatively inexpensive, and its recording equipment is compact and its maintenance is relatively easy. Therefore, it is used not only as a medium for facsimile machines and various computers but also in a wide range of fields.

It is desired that thermal recording paper can always perform stable recording even under various external environmental conditions. For example, when recording is performed under low humidity, troubles such as a decrease in stacking suitability (suitability for stacking the recording paper discharged from the recording device to be clean) due to a curl of the recording paper and a paper jam are likely to occur. Also, when printing is performed under high humidity, there is a problem that curl of the recording paper deteriorates stacking suitability.

In order to solve such problems, a back coat layer is provided on the back surface of the support to improve the stackability of the recording paper, and other attempts have been made.However, at present, sufficient recording paper has not been obtained. is there.

"Problems to be Solved by the Invention" In view of the present situation, the present inventors have conducted intensive studies on thermosensitive recording paper, and as a result, used a support having a specific dynamic wetting value and provided a specific backcoat layer. And found that the suitability for the stack was improved very efficiently.

"Means for Solving the Problems" The present invention provides a thermosensitive recording method in which a heat-sensitive recording layer containing a colorless or light-colored basic dye and a colorant capable of forming a color in contact with the dye is provided on a support. In the heat-sensitive recording paper, a base paper having a dynamic wetting value of −0.30 g or more after 2 seconds from water immersion is used as the support, and a layer containing a sugar alcohol is provided on the back surface. is there.

"Action" In the present invention, a layer containing a sugar alcohol is provided on the back surface of the thermal recording paper. Sugar alcohol is a generic term for polyhydric alcohols obtained by reducing the carbonyl group of a sugar molecule, and refers to tetrit, pentite, hexit and the like. The present inventors have found that when these substances are contained on the back surface of the thermal recording paper, not only curling can be prevented, but also curling at low humidity can be prevented. This is because by applying sugar alcohol, the base paper can maintain a sufficiently high moisture content even under low humidity, and can maintain flexibility, so that the curl is improved and the stacking performance of recording under low humidity is improved. It is expected to be improved.

Further, in the present invention, a base paper having a dynamic wetting value of -0.30 g or more after 2 seconds from immersion in water is used as a support for the thermal recording paper.

The dynamic wetting value is the dynamic wetting tester (WET-3000 /
(Manufactured by Resca Co., Ltd.), which is a value obtained by temporally measuring the wettability (adhesive force) of base paper with water. In particular,
Using the above-mentioned tester, the magnitude (adhesive force) of temporal wetting when a 2 × 5 cm test piece is immersed in water at a depth of 12 mm for 10 seconds at a speed of 16 mm / sec is measured.

The present inventors have further studied this wetting value and found that the wetting value two seconds after immersion in water has a very large effect on the thermal recording paper as a temporal wetting value measured by this tester. Was. Therefore, the dynamic wetting value in the present invention refers to the wetting value two seconds after immersion in water.

That is, if this value is small (the wettability of the base paper is small),
The coating liquid for the recording layer does not easily permeate into the base paper and curls easily occur. When a stock solution having a wetting value of less than -0.30 g is used, even if a sugar alcohol is applied to the back surface, curling cannot be sufficiently prevented, and the moisture content under low humidity cannot be maintained. Is difficult to obtain.

The heat-sensitive recording paper of the present invention is characterized in that base paper having a dynamic wetting value of -0.30 g or more is used, and a layer containing a sugar alcohol is provided on the back surface.

Also, as the dynamic wetting value increases, the penetration of moisture into the base paper increases, so that the curl tends to be less likely to occur, but the recording layer on the base paper surface is less likely to be smooth,
It is preferable to use a base paper having a dynamic wetting value of -0.30 to 0.20 g because there is a possibility that the quality such as the recording sensitivity may be deteriorated.

Examples of the sugar alcohol used in the present invention include tetrits such as D-trait, L-trait and erythritol; pentites such as D-arabit, L-arabit, xylit, adnit; Knit, L-mannit, D-id,
Hexit such as L-idit, D-talit, L-talit, dursit, allozursit and the like. Among these, D-sorbit, D-mannit, and dursit are preferred materials because they exist widely in nature.
Among them, the use of D-Sorbit is preferable because it can provide a thermosensitive recording paper having extremely excellent flexibility.

In addition, the application amount of these sugar alcohols is not particularly limited, but if it is too large, blocking is likely to occur,
If the amount is too small, the effect of the present invention cannot be obtained.
01~2.0g / m ^2, more preferably about it is adjusted in the range of about 0.04~0.5g / m ^2.

Further, the layer containing the sugar alcohol may be formed as a coating liquid obtained by mixing the sugar alcohol with an appropriate binder, and further, an inorganic pigment, a wax, a water-resistant It is also possible to add appropriate auxiliaries such as agents.

About the coating method, it can be formed according to a conventionally well-known conventional technique, for example, an air knife coater,
Blade coater, bar coater, gravure coater,
An appropriate coating device such as a curtain coater is used.

In the present invention, various types of colorless or light-colored and basic dyes constituting the recording layer of the thermosensitive recording paper 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- (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-bis (9-ethylcarbazol-3-yl) -6
Dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -6-dimethylaminophthalide,
Triallylmethane dyes of 3-p-dimethylaminophenyl-3- (1-methylpyrrol-3-yl) -6-dimethylaminophthalide, 4,4'-bis-dimethylaminobenzhydryl benzyl ether, Diphenylmethane dyes such as N-halophenyl-leuco auramine and N-2,4,5-trichlorophenyl leuco auramine; thiazine dyes such as benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue; 3-methyl-spiro-dinaphthopyran , 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-
Spiro dyes such as benzyl-spiro-dinaphthopyran, 3-methyl-naphtho (6'-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran, rhodamine-B-anilinolactam, rhodamine (p-nitroanilino) lactam, Lactam dyes such as rhodamine (o-chloroanilino) lactam, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-
Methoxyfluoran, 3-diethylamino-7-methoxyfluoran, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6,7-dimethylfluoran, 3- (N-ethyl-p-toluidino) -7-methylfluoran, 3-diethylamino-7-N-acetyl-N-methylaminofluoran, 3-diethylamino-
7-N-methylaminofluoran, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-N-methyl-N-benzylaminofluoran,
3-diethylamino-7-N-chloroethyl-N-methylaminofluoran, 3-diethylamino-7-N-diethylaminofluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-phenylaminofluor Orane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluoran, 3-diethylamino-6-methyl-7-phenylaminofluoran, 3
-Diphthylamino-6-methyl-7-phenylaminofluoran, 3-diethylamino-7- (2-carboxymethoxy-phenylamino) fluoran, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-
Phenylaminofluoran, 3-pyrrolidino-6-methyl-7-phenylaminofluoran, 3-piperidino-
6-methyl-7-phenylaminofluoran, 3-diethylamino-6-methyl-7-xylidinofluoran,
3-diethylamino-7- (o-chlorophenylamino) fluoran, 3-dibutylamino-7- (o-chlorophenylamino) fluoran, 3-pyrrolidino-6
Methyl-7-p-butylphenylaminofluoran, 3
-(N-methyl-NN-amyl) amino-6-methyl-7-phenylaminofluoran, 3- (N-ethyl-
Nn-amyl) amino-6-methyl-7-phenylaminofluoran, 3- (N-ethyl-N-isoamyl)
Amino-6-methyl-7-phenylaminofluoran,
3- (N-methyl-NN-hexyl) amino-6-methyl-7-phenylaminofluoran, 3- (N-ethyl-NN-hexyl) amino-6-methyl-7-phenylaminofluor Oran, 3- (N-ethyl-N-β-ethylhexyl) amino-6-methyl-7-phenylaminofluoran, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-phenyl Fluoran dyes such as aminofluoran and 3- (N-ethyl-N-cyclopentyl) amino-6-methyl-7-phenylaminofluoran; Of course, it is not limited to these dyes, and two or more dyes can be used in combination.

Various compounds are also known as colorants used in combination with the basic dyes, and examples thereof include the following.

4-tert-butylphenol, α-naphthol, β-naphthol, 4-acetylphenol, 4-tert-octylphenol, 4,4′-sec-butylidenediphenol,
4-phenylphenol, 4,4'-dihydroxy-diphenylmethane, 4,4'-isopropylidenediphenol, 2,2'-bis (4-hydroxyphenyl) -4-methylpentane, hydroquinone, 4,4'-cyclohexyl Silidenediphenol, 4,4 '-(1,3-dimethylbutylidene) bisphenol, 4,4'-dihydroxydiphenylsulfide, 4,4'-thiobis (6-tert-butyl-
3-methylphenol), 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-methoxydiphenylsulfone-4-hydroxy-4'-isopropoxydiphenylsulfone, -Hydroxy-3 ', 4'-trimethylenediphenylsulfone, 4-hydroxy3', 4'-
Tetramethylenediphenylsulfone, 3,4-dihydroxy-4'-methyldiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 1,3-di [2
-(4-hydroxyphenyl) -2-propyl] benzene, hydroquinone monobenzyl ether, bis (4-hydroxyphenyl) acetic acid butyl ester, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,4,4'-tri Hydroxybenzophenone, 2,2 ',
4,4'-tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, sec-butyl 4-hydroxybenzoate, 4-hydroxy Pentyl benzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate,
4-Hydroxybenzoic acid tolyl, 4-hydroxybenzoic acid chlorophenyl, 4-hydroxybenzoic acid phenylpropyl, 4-hydroxybenzoic acid phenethyl, 4-hydroxybenzoic acid-p-chlorobenzyl, 4-hydroxybenzoic acid-p-methoxybenzyl , Phenolic compounds such as novolak type phenolic resins and phenolic polymers,
Benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec-butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroishibenzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid Acid, salicylic acid, 3-isopropylsalicylic acid, 3-tert-butylsalicylic acid, 3,5-di-tert-britylsalicylic 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- Aromatic carboxylic acids such as di-α-methylbenzylsalicylic acid, and phenolic compounds, salts of the aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, etc. Organic acidic substances and the like. Of course, two or more of these colorants can be used as needed.

The use ratio of the basic dye and the colorant is appropriately selected depending on the needs of the basic dye and the colorant used, and is not particularly limited, but is generally 100 parts by weight of the basic dye. 100 to 700 parts by weight, preferably about 150 to 400 parts by weight of a color former is used.

A coating liquid containing these substances is generally prepared by using water as a dispersing medium, stirring with a ball mill, an attritor, a sand mill, or the like.
It is prepared by dispersing dyes and color formers together or separately by a pulverizer.

In such a coating solution, usually as a binder starches, hydroxyethylcellulose, methylcellulose,
Carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene / maleic anhydride copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, etc. 2 to 40% by weight of the total solid , Preferably about 5 to 25% by weight.

Further, various auxiliaries can be added to the coating solution, for example, dispersants such as sodium dioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol sulfate, sodium salt of fatty acid, and other defoaming agents. Agents, fluorescent dyes, coloring materials and the like.

In addition, inorganic pigments such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica, and activated clay can be added to improve the adhesion of scum to the recording head. Further, a dispersion or emulsion of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, or the like can be added so as not to cause sticking due to contact with a recording device or a recording head.

Further, if necessary, fatty acid amides such as stearic acid amide, stearic acid methylenebisamide, oleic acid amide, palmitic acid amide, and coconut fatty acid amide;
2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-3-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy Hindered phenols such as -5-tert-butylphenyl) butane, p-benzylbiphenyl, 1,2-bis (phenoxy) ethane, 1,2-bis (4
Ethers such as -methylphenoxy) ethane, 1,2-bis (3-methylphenoxy) ethane and 2-naphthol benzyl ether, dibenzyl terephthalate, dibenzyl oxalate, di (P-methylbenzyl) oxalate, Esters such as 1-hydroxy-2 naphthoic acid phenyl ester, 2- (2'-hydroxy-
An ultraviolet absorber such as 5'-methylphenyl) benzotriazole, 2-hydroxy-4-benzyloxybenzophenone, and various known heat-fusible substances can be used in combination as a sensitizer.

In the heat-sensitive recording paper of the present invention, the method for forming the recording layer is not particularly limited, and the above-described coating device is used.

The amount of the coating is not particularly limited, and is generally ² to 12 g / m ² by dry weight, preferably 3 to 10 g / m ² .
It is adjusted in the range of g / m ^2.

Note that an overcoat layer is provided between the recording layers of the support to enhance recording sensitivity and image quality, or to provide an undercoat layer for preventing head scum adhesion, or to protect the recording layer on the recording layer. It is also possible to provide.

"Examples" Hereinafter, the present invention will be described specifically with reference to examples, but is not limited thereto. In the examples, "parts" and "%" indicate "parts by weight" and "% by weight", respectively, unless otherwise specified.

Example 1 Preparation of solution A 3- (N-ethyl-N-isoamyl) amino-6-ethyl-7-phenylaminofluorane 10 parts 1,2-bis (3-methylphenoxy) ethane 20 parts Methyl cellulose 5% aqueous solution 20 Part water 40 parts This composition was pulverized with a sand mill until the average particle size became 2 μm.

Preparation of Solution B 4,4'-isopropylidene diphenol 30 parts Methyl cellulose 5% aqueous solution 40 parts Water 20 parts This composition was pulverized by a sand mill until the average particle diameter became 2 μm.

Formation of recording layer 90 parts of solution A, 90 parts of solution B, 30 parts of silicon oxide pigment (trade name: Mizukasil P-527, average particle size: 1.8 μm, oil absorption: 180 cc / 100 g, manufactured by Mizusawa Chemical Co., Ltd.), 20% 150 parts of an oxidized starch aqueous solution and 28 parts of water were mixed and stirred to obtain a coating liquid.

The resulting coating weight after drying on a base paper of the paper was 47 g / m ² as dynamic wetting value a coating solution is -0.05g is by coating and drying so that 5 g / m ² provided with a recording layer Was.

Formation of the back layer D- sorbitol after (Co. Kao, food additives for sorbit) coating weight of 2% aqueous solution was applied and dried so that 10 cc / m ^2, the heat-sensitive of the present invention Super calendering Recording paper was obtained.

Example 2 In forming the back surface of Example 1, D-mannitol was used instead of D-sorbitol (manitol, manufactured by Kao Corporation).
A heat-sensitive recording paper was obtained in the same manner as in Example 1 except that a 2% aqueous solution was used.

Comparative Example 1 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that a base paper having a dynamic wetting value of -0.35 g was used.

Comparative Example 2 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that a 2% aqueous solution of polyvinyl alcohol was used in place of D-sorbitol in forming the back layer of Example 1.

Comparative Example 3 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that water was used in place of D-sorbite in forming the back layer of Example 1.

The obtained five types of heat-sensitive recording papers were finished into a roll having a diameter of 40 mm and a diameter of 95 mm, and the stackability under low-humidity and high-humidity conditions was evaluated as described below.

[Stack suitability under low humidity conditions]

Leave the 40mm diameter winding under low humidity conditions (20 ° C, 20% RH) for 24 hours, then heat-sensitive facsimile (Matsushita Dentsu Co., Ltd., UF-100
At 0), 10 sheets of A4 size print record were made, and the suitability for stacking was evaluated based on the following criteria.

[Stack suitability under high humidity conditions]

After leaving the winding of 95mm diameter under high humidity condition (30 ℃ 80% RH) for 24 hours, heat-sensitive facsimile (Matsushita Dentsu Co., Ltd., UF-2)
And the same print record was made, and the suitability for stacking was evaluated according to the following criteria.

(Evaluation) A: Very good.

 ：: No trouble occurs.

 Δ: The recording paper after printing falls off the tray.

 X: The recording paper is jammed.

"Effects" As is clear from the results in Table 1, the heat-sensitive recording paper of the present invention had extremely excellent stacking characteristics.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-154991 (JP, A) JP-A-60-67191 (JP, A) JP-A-60-63195 (JP, A) JP-A-2- 227280 (JP, A) JP-A-3-133688 (JP, A) JP-A-58-228993 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5 / 28-5 / 34 B41M 5/38-5/40 D21H 1/00-3/82 D21H 19/00-21/56

Claims (1)

(57) [Claims] 1. A thermosensitive recording paper comprising a support having thereon a heat-sensitive recording layer containing a colorless or pale-colored basic dye and a colorant capable of forming a color upon contact with said dye. A heat-sensitive recording paper using a base paper having a dynamic wetting value of -0.30 g or more after 2 seconds from immersion and having a layer containing a sugar alcohol provided on the back surface.