JPH0648023A - Method for manufacturing thermal recording material - Google Patents

Abstract

(57) [Summary] [Purpose] To produce a thermosensitive recording material having high recording sensitivity and excellent storage stability of recorded images. [Structure] At least one basic dye on a support,
In the method for producing a heat-sensitive recording material, which comprises a thermosensitive coloring layer containing a color developing agent which can be colored by contact with the basic dye, and a protective layer is provided by the coating method, the coating method of the protective layer is , After applying a high-concentration protective layer coating liquid from the jet fountain onto the thermosensitive coloring layer, when measuring coating with the rod blade, rotate the rod in the reverse direction to the coating direction and rotate the peripheral speed against the coating speed. The method for producing a heat-sensitive recording material is characterized in that it is 1/100 or more. [Effect] A high-quality thermal recording material having high recording sensitivity, excellent storage stability of recorded images, and no scratch stains was obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermosensitive recording material, and more specifically, the present invention relates to a method for producing a thermosensitive recording material having high sensitivity and excellent storage stability of recorded images. .

[0002]

2. Description of the Related Art The heat-sensitive recording system is highly evaluated for its advantages that a color image can be obtained by simply heating it and that the recording apparatus can be made relatively simple and compact.
Widely used as various information recording methods for facsimiles, printers, word processors and the like. In particular, in recent years, improvements have been made in the apparatus of a facsimile printer using such a thermal recording system, and high-speed recording, which has been difficult in the past, has become possible. With the speedup of such equipment,
Further improvements in recording sensitivity are required for the heat-sensitive recording materials used for that purpose, and materials having excellent thermal responsiveness are being provided one after another due to the development of high-sensitivity technology in recent years.

The heat-sensitive recording material used in such a heat-sensitive recording method is generally a sheet-like support such as paper, synthetic paper, or plastic film, and a colorless or light-colored basic dye and the basic dye are brought into contact with each other. A thermosensitive coloring layer containing a color-developing substance such as a phenolic compound and an adhesive as main components is provided, and both color-developing substances are brought into contact with each other by heat to cause a reaction and color recording Images can be obtained.

However, conventionally, this type of heat-sensitive recording material has a drawback in storage stability in both the colored portion and the uncolored portion. That is, when oil or a plasticizer comes into contact with the surface of the thermosensitive coloring layer, the colored portion is discolored or the uncolored portion is not colored.
For example, if a plastic eraser is left on the surface of the thermosensitive coloring layer for a long time or is contacted with a vinyl chloride film for a long time, the plasticizer contained therein migrates and the colored image disappears. In addition, there are inconveniences such as decoloring with fingerprints, coloring with a fluorescent pen, and decoloring. If the organic solvent such as alcohol, toluene, or ethyl acetate is accidentally dropped or exposed to the vapor of the organic solvent, the uncolored portion develops color and becomes indistinguishable from the recorded image. There is also a drawback that stains (scratch stains) occur when the surface is lightly scratched with a nail.

As one of the means for solving the problems of the conventional heat-sensitive recording material, there is a laser facsimile using a heat fixing method of toner with plain paper as a recording medium. Has a big drawback that it is large, expensive, requires a high-output power supply, requires maintenance, and requires regular maintenance.

Therefore, in order to solve these problems while making the most of the advantages of the heat-sensitive recording material, many proposals have been made to provide a protective layer on the surface of the heat-sensitive color developing layer. (JP-A-48-516
44, JP-A-54-128347, JP-A-56-126193
JP-A-58-058434, JP-A-59-232893, JP-A-60-99696, JP-A-60-31996,
(Japanese Patent Laid-Open No. 1-230681, etc.)

Since the purpose of providing such a protective layer is to prevent the penetration of various chemical substances into the thermosensitive coloring layer, that is, to impart a barrier property, it is extremely difficult to solve the above-mentioned problem of decoloring by oil or plasticizer. It is effective and also has a great effect on scratch stains. However, when a protective layer is provided on the thermosensitive coloring layer, there is a drawback that the transfer of heat from the thermal head is impeded during printing and the sensitivity is remarkably lowered. In particular, in thermosensitive recording materials for which high sensitivity is required, such as for facsimiles, the decrease in sensitivity due to the protective layer has been a serious problem. In this case, reduction in the sensitivity can be suppressed by reducing the coating amount of the protective layer, but there is a limit in terms of barrier properties.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above problems in a thermal recording material and provides a method for producing a thermal recording material having high sensitivity and excellent storage stability of a recorded image. To do.

[0009]

Means for Solving the Problems As a result of repeated studies on the method of forming a protective layer on the thermosensitive coloring layer, the present inventors have found that
It has been found that the barrier property of the formed layer is greatly influenced by the solid content concentration of the protective layer coating liquid when the protective layer is applied. That is, the higher the solid content of the protective layer coating liquid during coating, the higher the barrier property of the formed protective layer. The reason for this is that when the solid content concentration of the coating liquid is high, the penetration and migration of the coating liquid into the lower thermosensitive color developing layer between the coating and drying is less than when the coating liquid is low, It is considered that the generation of holes is suppressed and the coating film becomes denser. In this way, a protective layer having a high barrier property can be obtained by increasing the concentration of the protective layer coating liquid.However, the conventional method such as air knife method, gravure method, roll coater method, bar coater method, spray method, dip method, extrusion method, etc. The coating method used for coating the protective layer has a limit in increasing the concentration of the coating liquid.

On the other hand, there are a tip blade method and a rod blade method as coating methods which enable coating at a high concentration.
These methods have the advantage that a coating surface with high uniformity and high smoothness can be obtained, but at the same time, streaks and scratches tend to occur due to foreign substances and dust mixed in the coating liquid. Therefore, these methods have not been conventionally used for coating the protective layer. A method of removing foreign matter using a screen is also effective as a solution to this problem, but in addition, the present inventors can improve it very effectively by increasing the rotation speed of the rod in the rod blade method. I found more. That is, the rod is usually rotated in the reverse direction with respect to the coating direction, but its peripheral speed is 1/200 to the coating speed.
Streaks occur frequently at a low speed of 400, but the frequency of occurrence decreases as the rotation speed increases.
If the coating speed is 1/100 or more, no problem will occur. This enabled coating without streaks and scratches.

According to the present invention, a thermosensitive coloring layer containing at least one basic dye and a developer capable of developing a color by contacting with the basic dye is provided on a support, and a thermosensitive coloring layer is formed thereon by a coating method. In the method for producing a heat-sensitive recording material provided with a protective layer, the method for applying the protective layer is such that a high-concentration protective layer coating solution is applied from a jet fountain onto the thermosensitive coloring layer, and then applied with a rod blade. The method relates to a method for producing a heat-sensitive recording material, characterized in that the rotation speed is in the reverse direction to the coating direction and the peripheral speed is 1/100 or more of the coating speed.

In the present invention, the coating liquid used for coating the protective layer has a solid content concentration of 10 to 25% by weight. When the solid content concentration is 10% by weight or less, the coating solution permeates or migrates into the thermosensitive color developing layer before the coating film is dried, which is not preferable, and when it is 25% by weight or more, the fluidity of the coating solution is poor. However, it is not preferable because not only is it difficult to apply the coating, but also the coating amount increases and the sensitivity decreases due to the protective layer.

The rod blade method adopted in the present invention rotates the rod in the reverse direction with respect to the coating direction and at a peripheral speed of 1/100 or more of the coating speed. It is important that the peripheral speed of the rod is 1/100 or more of the coating speed, and usually 1/100 to 1/10, but 1/25 to 1/100 is preferable. When the peripheral speed of the rod is 1/10 or more, not only is there no improvement effect, but the coated surface becomes rough, which is not preferable.

According to the coating method of the present invention described above, not only a protective layer having excellent uniformity and high barrier property can be formed on the thermosensitive color developing layer, but also the coating amount of the protective layer can be greatly reduced. In this case, it is possible to suppress the decrease in sensitivity caused by the protective layer. In addition, by adopting the rod blade method, there is an advantage that high-speed coating is possible and productivity can be improved as compared with other coating methods. As described above, according to the method of the present invention,
While having excellent storage stability, it has become possible to obtain a high sensitivity which has not been obtained by a conventional thermal recording material provided with a protective layer.

As the basic dye constituting the heat-sensitive color developing layer of the present invention, known colorless or light-colored basic dyes can be used, and specific examples are as follows. (1) Examples of triallylmethane compounds include 3,3
-Bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, and the like. (2) Examples of diphenylmethane compounds include 4,
4'-bis-dimethylaminobenzhydrylbenzyl ether, N-2,4,5-trichlorophenylleuco auramine, N-halophenyl-leuco auramine and the like.

(3) Examples of xanthene compounds include rhodamine B-anilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-butylaminofluorane, 3-diethylamino-7- (2 -Chloroanilino) fluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-ethyl-tolylamino-6-methyl-7-anilinofluorane, 3-cyclohexyl-methylamino-6-methyl-
7-anilinofluorane, 3-diethylamino-6-chloro-7- (β-ethoxyethyl) aminofluorane,
3-Diethylamino-6-chloro-7- (γ-chloropropyl) aminofluorane, 3-dibutylamino-6-
Methyl-7-anilinofluorane, 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3-ethyl-isoamylamino-6-methyl-7-anilinofluorane , 3-dibutylamino-7-
Chloroanilinofluorane etc. These dye precursors can be used alone or in combination of two or more, and are appropriately selected and used depending on the application of the heat-sensitive recording material and desired properties.

Further, as a developer which is a constituent of the thermosensitive color developing layer, a phenol derivative, an aromatic carboxylic acid derivative, acid clay, a novolac resin, a metal complex or the like is used. Specific examples of some of these include p-octylphenol and p-tert as phenol derivatives.
-Butylphenol, p-phenylphenol, 2,2
-Bis (p-hydroxyphenyl) propane, 1,1-
Bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) pentane, 1,1-bis (p-hydroxyphenyl) hexane, 2,2-bis (p-hydroxyphenyl) hexane, 1, 1-bis (p-hydroxyphenyl) -2-ethylhexane,
2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, dihydroxydiphenyl ether,
4,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropyloxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone and the like can be mentioned.

As the aromatic carboxylic acid derivative, p is
-Hydroxybenzoic acid, butyl p-hydroxybenzoate, 3,5-di-tert-butylsalicylic acid, 3,5
-Di-α-methylbenzyl salicylic acid, polyvalent metal salts of the above carboxylic acids, and the like can be mentioned. Of these, bisphenols are particularly preferable.

The mixing ratio of the basic dye and the color developer is not necessarily limited and may be adjusted according to the materials used. Generally, it is 1 to 1 with respect to 1 part by weight of the basic dye.
0 parts by weight, preferably 1.5 to 5 parts by weight of developer are used.

In the present invention, a sensitizer can be used to improve the sensitivity of the heat-sensitive recording material. Examples of the sensitizer include aromatic ethers, heat-fusible substances such as esters and / or fatty acid amides, and specifically, stearic acid amide, ethylenebisstearic acid amide, methylol behenic acid amide, oleic acid amide, Fatty acid amides such as palmitic acid amide, p-benzylbiphenyl, dibenzyl terephthalate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, di-p-chlorobenzyl oxalate, di-p-methylbenzyl oxalate, adipine Examples thereof include acid di-o-chlorobenzyl, 1,2-di (3-methylphenoxy) ethane, and 1,2-bis (3,4-dimethylphenyl) ethane.

These basic dyes, color developers, and sensitizers generally use water as a dispersion medium, and polyacrylamide, by various wet pulverizers such as a ball mill, a co-ball mill, an attritor, and a vertical or horizontal sand mill. It is used for preparing a heat-sensitive color-developing paint after it is dispersed with a water-soluble synthetic polymer compound such as polyvinylpyrrolidone, polyvinyl alcohol, methylcellulose, and a styrene-maleic anhydride copolymer salt, and other surfactants to prepare a dispersion liquid.
The sensitizer may be added to either or both of the basic dye and the color developer and dispersed together, or in some cases, a eutectic may be prepared in advance and then dispersed.

In the present invention, various known coloring layer constituent materials are used in the thermosensitive coloring layer. A water-soluble binder is generally used, and polyvinyl alcohol, polyamide, styrene-acrylic acid copolymer salt, styrene-maleic anhydride copolymer salt, ethylene-maleic anhydride copolymer salt, diisobutylene- Examples include water-soluble synthetic polymer compounds such as maleic anhydride copolymer salts, and water-soluble natural polymer compounds such as methyl cellulose, other cellulose derivatives, starch, starch derivatives, gelatin, and casein, or derivatives thereof. . Also, a water resistance imparting agent may be added for the purpose of imparting water resistance to these binders,
Synthetic polymer emulsion, specifically SBR latex, acrylic resin emulsion and the like can also be added.

In addition, examples of the material forming the thermosensitive coloring layer include inorganic or organic pigments, waxes, metal soaps and the like. Inorganic pigments include calcium carbonate, kaolin, calcined kaolin, talc, wax, diatomaceous earth, aluminum oxide, aluminum hydroxide, magnesium hydroxide, magnesia, titanium dioxide, barium carbonate, barium sulfate, fine silicic acid, calcium silicate, aluminum silicate. However, examples of the organic pigment include urea, phenol, epoxy, styrene, nylon, polyethylene, melamine, and benzoguanamine resin. Examples of the wax include paraffin wax, carnauba wax, microcrystalline wax, polyethylene wax, and higher fatty acid ester wax. Examples of the metal soap include higher fatty acid polyvalent metal salts, that is, zinc stearate, aluminum stearate, calcium stearate, zinc oleate and the like.

Further, if necessary, a surfactant, an antistatic agent, an ultraviolet absorber, a preservative improving agent, a fluorescent dye, a coloring dye, etc. may be added. In particular, it is desirable to add a storability improver in order to prevent the recorded image from being erased. Examples of the preservability improver include 1,3,5-tris (4-tert.
-Butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris ( 2-Methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1-bis (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4 ′-(1-phenylethylidene)
Bisphenol, 4,4 '-[1,4-phenylenebis (1-methylethylidene)] bisphenol, 4,4'
-[1,3-phenylene bis (1-methylethylidene)] bisphenol and other phenolic compounds and 4- (2-methyl-1,2-epoxyethyl) diphenyl sulfone, 4- (2-ethyl-1,2) -Epoxyethyl) diphenyl sulfone, 4- (2-methyl-glycidyl) diphenyl sulfone, 4- (2-ethyl-glycidyl) diphenyl sulfone, 4- (2-butyl-glycidyl) diphenyl sulfone, 4- (3-methyl- 3,4
-Epoxybutyl) diphenylsulfone, 4- (2-methyl-3,4-epoxybutyl) diphenylsulfone,
4- (2-methyl-2,3-epoxybutyl) diphenyl sulfone, 4- (2-methyl-1,2-epoxyethyloxy) diphenyl sulfone, 4- (2-methyl-
2,3-epoxybutyloxy) diphenyl sulfone,
4- (2-methyl-1,2-glycidyloxy) diphenyl sulfone, 4- (2-methyl-glycidyloxy)
-4'-chlorodiphenyl sulfone, 4- (2-methyl-glycidyloxy) -4'-bromodiphenyl sulfone, 4- (2-methyl-glycidyloxy) -4'-methyldiphenyl sulfone, 4- (2-methyl -Glycidyloxy) -2 ', 4'-dimethyldiphenyl sulfone, 4- (2-methyl-glycidyloxy) -2',
4'-dichlorodiphenyl sulfone, 4- (2-methyl-glycidyloxymethoxy) diphenyl sulfone, 4
And diphenyl sulfone derivatives such as-(2-methyl-glycidyloxy) -4 '-(p-methoxybenzyloxy) diphenyl sulfone.

These materials are mixed and then applied to the support. The support is not particularly limited, and includes high-quality paper, medium-quality paper, glossy paper, coated paper, art paper, cast-coated paper and the like, synthetic paper, synthetic fiber paper,
A synthetic resin film, a laminate of these, or the like is appropriately selected and used.

As the method for forming the thermosensitive coloring layer, a known coating method such as an air knife method, a blade method, a gravure method, a roll coater method, a spray method, a dip method, a bar method, and an extrusion method is used to form an undercoat layer on the undercoat layer. It is formed by coating and drying, but it is preferable to adopt a coating method capable of forming a coating layer having a good surface property such as a blade. Even if it is applied simultaneously with the protective layer described below,
You may apply | coat sequentially. Further, after forming the heat-sensitive color-developing layer, a surface smoothing treatment such as super calendering can be applied if necessary. Further, the coating amount of the thermosensitive coloring layer is not particularly limited, and usually 1 to 1 by dry weight.
12 g / m ^2, is adjusted preferably in the range of 3 to 8 g / m ^2.

In the present invention, the protective layer provided on the thermosensitive color developing layer contains a water-soluble polymer and a pigment as main components, and a cross-linking agent, wax, metal soap and the like can be used if necessary. As the water-soluble polymer, those having high resistance to oil, plasticizer, etc., good film-forming property and strong coating film strength are desirable. Specific examples of such water-soluble polymer include polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, alkyl-modified polyvinyl alcohol, styrene-maleic anhydride copolymer salt, isobutylene-maleic anhydride copolymer salt. , Styrene-acrylic acid copolymer salt, polyacrylamide, starch, chitosan, casein, gelatin, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose and the like. To impart water resistance to these water-soluble polymers, crosslinking agents such as melamine, epoxy, aziridine, glyoxal, dimethylolurea, polyaldehyde, and zirconium salt can be used in combination.

Examples of the pigment include calcium carbonate, aluminum hydroxide, clay, talc, agate stone, diatomaceous earth, aluminum silicate, calcium silicate, finely divided silicic acid, magnesium carbonate, magnesium hydroxide, magnesium oxide, barium carbonate, Examples thereof include inorganic pigments such as barium sulfate, zinc oxide, titanium dioxide, aluminum oxide and calcined clay, starch particles, organic pigments such as urea, melamine, phenol, benzoguanamine, epoxy, polystyrene, polyethylene, nylon and silicone resin.

Examples of waxes and metal soaps include paraffin wax, polyethylene wax, carnauba wax, microcrystalline wax, fatty acid amides such as stearic acid amide, oleic acid amide, erucic acid amide and behenic acid amide, and stearic acid. Examples thereof include higher fatty acid metal salts such as zinc, calcium stearate, aluminum stearate, and zinc behenate. In addition, various additives such as an oil repellent, an antifoaming agent, a viscosity modifier, a surfactant and a fluorescent dye may be added within a range that does not impair the effects of the present invention.

After forming a protective layer on the thermosensitive coloring layer, it is possible to carry out post-treatment by a known technique. For example, calender treatment for improving sensitivity and image quality can be performed, and oil and a plasticizer can be penetrated from the back surface. A back layer may be provided on the surface opposite to the surface on which the recording layer is formed for the purpose of suppressing or curling. Also,
Various modifications such as providing an undercoat layer under the thermosensitive coloring layer may be carried out if necessary.

[0031]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Further, parts and% in the examples represent parts by weight and% by weight, respectively.

Example 1 Formation of thermosensitive coloring layer (1) Preparation of basic dye dispersion 3- (n-ethyl-n-isoamylamino) -6-methyl 20 parts -7-anilinofluorane polyvinyl alcohol 10% liquid 10 parts water 40 parts A vertical sand mill (manufactured by AIMEX Co., Ltd.,
It was pulverized with a sand grinder) until the average particle size became 0.5 μm. (2) Preparation of color developer dispersion 4-hydroxy-4-isopropoxydiphenyl sulfone 10 parts p-benzylbiphenyl 10 parts polyvinyl alcohol 10% liquid 10 parts water 40 parts This composition was prepared as the dye precursor dispersion. By the same method as the above method, the particles were pulverized until the average particle diameter became 1.5 μm. (3) Preparation of Thermosensitive Coloring Layer Coating Liquid 40 parts of the above dye precursor dispersion liquid, and developer dispersion liquid 16
0 parts to 60 parts calcium carbonate, 60 parts 10% aqueous polyvinyl alcohol solution, 50% SBR latex 25
Parts, 30 parts of 30% zinc stearate dispersion, and 50 parts of water were mixed and stirred to prepare a thermosensitive color developing layer coating liquid. The coating amount after drying this coating solution on the felt side of the paper support is 5.0 g /
A thermosensitive color-developing layer was formed by coating and drying with a blade coater so as to be m ² .

Formation of protective layer Polyvinyl alcohol 50 parts (Kuraray Co., Ltd., PVA 117) Kaolinite clay 35 parts (EMC, UW-90) Glyoxal 5 parts Zinc stearate emulsion 10 parts (Chukyo Yushi Co., Ltd.) , Hydrin Z-7) The above composition was blended at the above solid content ratio to obtain a solid content concentration of 20.
% Protective layer coating solution was prepared. A rod diameter of 10 m is obtained by the rod blade method on the thermosensitive coloring layer previously formed by this coating liquid.
mφ, rod rotation speed 210 rpm (reverse rotation), coating speed 600 m / min (rod peripheral speed / coating speed = 1 /
In 91), coating and drying were performed so that the coating amount after drying was 1.0 g / m ² . After that, smoothing treatment was performed with a super calendar to obtain a heat-sensitive recording material.

[0033]

Example 2 Thermal recording was carried out in the same manner as in Example 1 except that the rotational speed of the rod was changed to 700 rpm in the coating method of the protective layer of Example 1 (rod peripheral speed / coating speed = 1/27). Got the material.

[0034]

Example 3 A thermosensitive recording material was obtained in the same manner as in Example 1 except that water was added to the coating solution for protective layer prepared in the same manner as in Example 1 to dilute it to a solid concentration of 12%. .

[0035]

Comparative Example 1 Thermal recording was carried out in the same manner as in Example 1 except that the rotational speed of the rod was changed to 160 rpm in the coating method for the protective layer of Example 1 (rod peripheral speed / coating speed = 1/119). Got the material.

[0036]

[Comparative Example 2] In the coating method of the protective layer of Example 1, the rotation speed of the rod was 1200 rpm, and the coating speed was 300 m.
/ Min (rod peripheral speed / coating speed = 1/8)
A thermosensitive recording material was obtained in the same manner as in Example 1 except for the above.

[0037]

Comparative Example 3 A thermosensitive recording material was obtained in the same manner as in Example 1 except that water was added to the protective layer coating solution prepared in the same manner as in Example 1 to dilute it to a solid content concentration of 8%. .

[0038]

Comparative Example 4 In the coating method for the protective layer of Example 1, the rotation speed of the rod was changed to 70 rpm (rod peripheral speed /
A thermal recording material was obtained in the same manner as in Example 1 except that the coating speed was 1/273).

[0039]

Comparative Example 5 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the tip blade method was used instead of the rod blade method in the protective layer coating method of Example 1.

[0040]

Comparative Example 6 Water was added to the protective layer coating liquid prepared in the same manner as in Example 1 to obtain a protective layer coating liquid having a solid content concentration of 8%.
Coating speed of this coating liquid is 200m / m by air knife method.
On the same thermosensitive coloring layer as in Example 1 under the condition of in, the coating amount after drying was 1.0 g / m ² and the coating was dried. Then, the same smoothing treatment as in Example 1 was performed to obtain a heat-sensitive recording material.

[0041]

Comparative Example 7 A thermosensitive recording material was prepared in the same manner as in Comparative Example 3 except that the coating amount of the protective layer after drying was changed to 3.0 g / m ² in the coating of the protective layer of Comparative Example 5. Obtained.

[0042]

Comparative Example 8 A thermal recording material was obtained in the same manner as in Comparative Example 3 except that the protective layer of Comparative Example 3 was coated at a coating speed of 150 m / min by the bar coater method.

The recording sensitivity and vinyl chloride film resistance of the heat-sensitive recording material thus obtained were evaluated. Recording sensitivity is measured by Matsushita Electric Transmission Co., Ltd. high-speed facsimile: UF-
Printing and recording were performed using a standard chart No. 2 of the Institute of Image Electronics Engineers on 60 machines, and the color density at that time was recorded by a Macbeth densitometer RD-9.
The value was measured at 14 and set to a value representative of the recording sensitivity of the recording material. The vinyl chloride film resistance is measured by measuring the recording sensitivity, and the vinyl chloride film (Mitsui Toatsu Co., Ltd. Hilap K
(MA) was adhered and allowed to stand at 25 ° C. for 1 week, and then the residual ratio of the post-treatment concentration that withstands the original concentration was displayed. The results are shown in Table 1.

[0044]

【table】

[0045]

According to the method of the present invention, the recording sensitivity is high,
It has become possible to manufacture a high-quality thermal recording material which is excellent in storage stability of recorded images and is free from scratch stains.

Claims (1)

[Claims] 1. A thermosensitive color-developing layer containing at least one basic dye and a color developing agent capable of developing a color on contact with the basic dye is provided on a support, and a protective layer is formed thereon by a coating method. In the method for producing a heat-sensitive recording material provided with, the method of coating the protective layer, after coating a high-concentration protective layer coating liquid from the jet fountain on the heat-sensitive color developing layer, when measuring coating with a rod blade, A method for producing a heat-sensitive recording material, characterized in that the rotation is in the reverse direction with respect to the coating direction and the peripheral speed is 1/100 or more of the coating speed.