JPH06247046A - Heat sensitive recording material - Google Patents

Abstract

PURPOSE:To make matching properties with a thermal head favorable, by a method wherein a heat sensitive color developmemt layer which consists mainly of leuco dyes and a developer and is compounded with calcium salt of carboxy modified polyvinyl alcohol is provided on a substrate. CONSTITUTION:Fixed quantities each of leuco dyes, a developer and calcium salt of carboxy modified polyvinyl alcohol are pulverized, agitated and dispersed within water dispersion of completely saponified or partly saponified polyvinyl alcohol and a coating liquid for a heat sensitive recording layer is prepared. The coating liquid for the heat sensitive recording layer is applied onto a substrate such as a plastic film or synthetic paper, dried for formation of the heat sensitive recording layer and a heat sensitive recording material is obtained. In addition, the heat sensitive recording layer consisting mainly of the leuco dyes and developer is provided on the substrate to which a protective layer consisting mainly of calcium salt of carboxy modified polyvinyl alcohol is laminated and heat sensitive recording material can be obtained also. The obtained heat sensitive recording material improves in plasticizer resistance, water resistance and water separation resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a heat-sensitive recording material which utilizes color development between a leuco dye and a color developer.

[0002]

2. Description of the Related Art In recent years, a recording material having a thermosensitive coloring layer capable of coloring a recorded image on a support such as paper, synthetic paper, plastic film, etc. by causing a chemical or physical change by heat energy is simply heated. You can get a record just by doing
Printers, facsimiles, recorders, etc. are advantageous because they do not require complicated processing such as development and fixing, do not generate noise during recording, and are relatively easy to manufacture and inexpensive. It is widely used in various information devices and measuring instruments. As these heat-sensitive recording materials, many have been put to practical use in the past, but among them, triphenylmethane-based, fluoran-based, spiropyran-based colorless or slightly pale leuco dyes and the leuco dyes A thermosensitive recording material containing an acidic substance such as an organic acid or a phenolic acidic substance as a color-forming component in the thermosensitive color-developing layer that reacts with heat to develop a leuco body, has a high coloring density of a recorded image and is clear. Therefore, it is used as a particularly useful recording material.

Further, the application of the above-mentioned leuco dye and an acidic substance to a wrapping paper for an automatic ticket vending machine such as a commuter ticket, a bar code paper in a POS system, a display label for a gift certificate, and the like is being promoted. However, we have not yet obtained satisfactory results. For example, in the case of the above-mentioned ticket paper, after printing with a thermal line printer, it is placed in a transparent vinyl case (periodical case), and in the case of a bar code paper display label, after printing with a label printer, the product is printed. Each of them is used in a state in which the above-mentioned film or the like is in contact with the surface of the thermosensitive coloring layer such that it is stuck on or under a wrap film such as polyvinyl chloride for packaging and placed on top of it. At this time, dioctyl adipate (DO) is added to these films to improve flexibility.
A) and a plasticizer such as dioctyl phthalate (DOP) are contained, and the disadvantage is that these plasticizers erase the color of the image portion thermally printed by the printer. Further, in the heat-sensitive recording material, there are also problems such as coloring of the final print portion when contacted with an alcohol-based chemical, decolorization of the print portion (image) due to contact with water, and peeling of the heat-sensitive layer.

On the other hand, when a thermal recording material is printed by a thermal head such as a thermal line printer or a thermal label printer, the thermal head is deteriorated due to abrasion of the print due to dust adhered to the thermal head, and is also called electrolytic corrosion. The matching property between the thermal recording material and the thermal head is still insufficient, such as defective printing due to dot breakage due to electrical corrosion of the thermal head.

[0005]

DISCLOSURE OF THE INVENTION The present invention overcomes the above-mentioned problems and is a heat-sensitive material which is excellent in plasticizer resistance, chemical resistance, water resistance, water peeling resistance, and matting with a thermal head. The purpose is to provide a recording material.

[0006]

That is, according to the present invention,
A thermosensitive recording material comprising a support and a thermosensitive coloring layer containing a leuco dye and a color developer as main components, characterized in that a calcium salt of carboxy-modified polyvinyl alcohol is used in the thermosensitive coloring layer. Will be provided.
Further, according to the present invention, a thermosensitive coloring layer mainly containing a leuco dye and a color developer is provided on a support, and a protective layer mainly containing a calcium salt of carboxy-modified polyvinyl alcohol is provided on the thermosensitive coloring layer. A heat-sensitive recording material is provided. Further, according to the present invention, an intermediate layer containing a calcium salt of carboxy-modified polyvinyl alcohol as a main component is provided on a support, and a thermosensitive coloring layer containing a leuco dye and a developer as a main component is further provided. A heat-sensitive recording material is provided. Further according to the invention,
Provided is a heat-sensitive recording material characterized in that a backcoat layer containing a calcium salt of carboxy-modified polyvinyl alcohol as a main component is provided on the back surface of a support (the surface provided with a heat-sensitive color forming layer is the front surface).

The present invention will be described in more detail below. In the present invention, when a calcium salt of carboxy-modified polyvinyl alcohol is used for the protective layer, it is effective in all of plasticizer resistance, chemical resistance, water resistance, water peeling resistance, and matching with the thermal head. Further, in the present invention, when the calcium salt of carboxy-modified polyvinyl alcohol is used for the thermosensitive coloring layer and the intermediate layer, it is slightly lower than when it is used for the protective layer, but a great effect is obtained as compared with the conventional thermosensitive recording material. is there. Furthermore, in the present invention, when a calcium salt of carboxy-modified polyvinyl alcohol is used in the back layer, the same effects as in the case of the protective layer are obtained with respect to the plasticizer resistance, chemical resistance, water resistance, and water peeling resistance of the back surface. Show.

Whether or not the calcium salt of carboxy-modified polyvinyl alcohol in the present invention exhibits an excellent effect is not clear at this time, but it is presumed that it is due to the following mechanism.

That is, the calcium salt of carboxy-modified polyvinyl alcohol is the same as commonly used saponified or partially saponified polyvinyl alcohol and modified polyvinyl alcohol (carboxy modified sodium or potassium salt, methylol modified or alkoxy modified polyvinyl alcohol, etc.). Similarly, it is a water-soluble resin, and in particular,
Since the film-forming property is better than other water-soluble resins, it is possible to form a thin film with few coating film defects and good barrier properties. Further, in general, polyvinyl alcohols are insufficient in terms of water peeling resistance because they are water-soluble resins.
Although it is the present situation that the water peeling resistance is improved by the addition of a cross-linking agent, the calcium salt of the carboxy-modified polyvinyl alcohol used in the present invention cross-links the calcium ion of the divalent metal in its chemical structure. It is expected to be used as a chemical agent and to significantly improve the water peeling resistance.

In general, polyvinyl alcohol needs to be saponified with sodium hydroxide or the like in the manufacturing process, and even with completely saponified polyvinyl alcohol, sodium ions remain in the order of several thousand PPM. Further, in carboxy-modified polyvinyl alcohol, sodium ions remain on the order of tens of thousands of PPM because sodium ions are added to the carboxyl groups. It is known that the sodium ion of these alkali metals gives a matching property with the thermal head, and in particular, causes the thermal head to corrode due to electrolytic corrosion to cause dot breakage during printing.

Calcium in the carboxy-modified polyvinyl alcohol according to the present invention is an alkaline earth metal, and its calcium ion has less of the above-mentioned problems. Particularly importantly, calcium ion acts as a cross-linking agent, so that it is in a free state. It is presumed that it is difficult to exist, so that the matching property with the thermal head is significantly improved. From the above, it is considered that the problems of the prior art can be greatly improved by using a calcium salt of carboxy-modified polyvinyl alkyl as an additive in the present invention.

In the present invention, it is also possible to use a conventionally used crosslinking agent together with the calcium salt of carboxy-modified polyvinyl alcohol. Examples of the cross-linking agent used with the calcium salt of the carboxy-modified polyvinyl alcohol of the present invention include fully saponified or partially saponified polyvinyl alcohol, modified polyvinyl alcohol (for example, methylol-modified, alkoxy-modified or silica-modified polyvinyl alcohol), starch and derivatives thereof, Cellulose derivatives such as methoxy cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid ternary copolymer In addition to water-soluble polymers such as coalesce, styrene / maleic anhydride copolymer calcium salt, polyacrylamide, calcium alginate, gelatin and casein, polyvinyl acetate , Polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, styrene / butadiene / acrylic acid copolymer Such as latex.

The thermosensitive coloring layer in the present invention contains a leuco dye and a color developer as main components, and the leuco dye is applied alone or in combination of two or more kinds. What is applied to the thermal recording material of the species is optionally applied, for example, trienyl methane series,
A leuco compound that forms a dye such as a fluoran-based dye, a phenothiazine-based dye, an auramine-based dye, or a spirobilan-based dye is preferably used. Specific examples of such a leuco base include those shown below.

3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis ( p-dimethylaminophenyl) -6-diethylaminophthalide,
3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7 -Dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-
Diethylamino-7,8-benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-
(Np-tolyl-N-ethylamino) -6-methyl-
7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2- {3 6-bis (diethylamino)-
9- (o-chloroanilino) xanthylbenzoic acid lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino -7- (o-chloroanilino) fluorane, 3-N-methyl-N-amylamino-6-methyl-
7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N, N -Diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluorane, benzoylleucomethylene blue, 6'-chloro-8'-
Methoxy-benzoindolino-pyrrilospirane, 6'-
Bromo-3'-methoxy-benzoindolino-pyrrilospirane, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-chlorophenyl) phthalide, 3- (2'- Hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy-5 '
-Methylphenyl) phthalide, 3- (2'-methoxy-
4'-diethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino -7-
Trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-
(Di-p-chlorophenyl) methylaminofluorane,
3-Diethylamino-5-chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-O-toluidino) -7- (α-phenylethylamino) fluorane 3-diethylamino-7- (o- Methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-
Methyl-7- (α-phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane,
2-chloro-3- (N-methyltoluidino) -7- (p
-N-butylanilino) fluorane, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7
-Α-naphthylamino-4'-bromofluorane, 3-
Diethylamino-6-methyl-7-mesitidino-4 ',
5'-benzofluorane etc.

As the color developer used in the present invention, various electron-accepting substances that react with the above leuco dye upon heating to develop a color are applied. Specific examples thereof are shown below. Examples thereof include phenolic substances, organic or inorganic acidic substances or salts thereof.

Gallic acid, salicylic acid, 3-isopropylsalicylic acid, 3-cyclohexylsalicylic acid, 3-isopropylsalicylic acid, 3-cyclohexylsalicylic acid,
3,5-di-tert-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4,4′-isopropylidenediphenol, 1,1′-isopropylidenebis (2-chlorophenol), 4, 4'-isopropylidene bis (2,6-dibromophenol), 4,4'-isopropylidene bis (2,6-dichlorophenol),
4,4'-isopropylidene bis (2-methylphenol), 4,4'-isopropylidene bis (2,6-dimethylphenol), 4,4'-isopropylidene bis (2-tert-butylphenol), 4, 4'-se
c-butylidene diphenol, 4,4′-cyclohexylidene bisphenol, 4,4′-cyclohexylidene bis (2-methylphenol), 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α -Naphthol, β-naphthol,
3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolac type phenol resin, 2,2'-thiobis (4,4)
6-dichlorophenol), catechol, resorcin,
Hydroquinone, pyrogallol, phloroglysin, phloroglysin carboxylic acid, 4-tert-octylcatechol 2,2′-methylenebis (4-chlorophenol),
2,2'-methylenebis (4-methyl-6-tert-
Butylphenol), 2,2'-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, p-
Benzyl hydroxybenzoate, p-hydroxybenzoic acid-p-chlorobenzyl, p-vidroxybenzoic acid-o-
Chlorobenzyl, p-hydroxybenzoic acid-p-methylbenzyl, p-hydroxybenzoic acid-n-octyl, benzoic acid, zinc salicylate, 1-hydroxy-2-naphthoic acid, 2-vidroxy-6-naphthoic acid, 2- Zinc hydroxy-6-naphthoate, 4-hydroxy-4'-chlorodiphenyl sulfone, bis (4-hydroxyphenyl) sulfide, 2-hydroxy-p-toluic acid,
3,5-di-t-butylsalicylic acid, tartaric acid, acetic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid and the like.

In the present invention, in order to bond and support the leuco dye and the color developer on a support, various conventional binders can be appropriately used in combination. In the present invention, the leuco dye and the color developer may be used, if necessary, in combination with auxiliary additive components such as a filler, a thermoplastic substance, and a surfactant, which are commonly used in heat-sensitive recording materials of this type. You can In this case, as the filler, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay,
Inorganic fine powders such as talc and surface-treated calcium and silica, as well as organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer and polystyrene resin can be mentioned. Examples of heat-fusible substances include higher fatty acids or their esters, amides or metal salts, various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, Examples thereof include those having a melting point of about 50 to 200 ° C. such as 3,4-epoxy-dialkyl hexahydrophthalate, higher ketones, and other heat-fusible organic compounds.

Further, in order to further improve the water peeling resistance of the heat-sensitive recording material using the calcium salt of carboxy-modified polyvinyl alcohol of the present invention, a water-proofing agent such as polyamide resin, melamine resin or glyoxal, if necessary, In order to improve the head matching property, a filler commonly used in heat-sensitive recording materials such as calcium carbonate, clay and urea formalin resin, and a lubricant such as zinc stearate and polyethylene wax can be further contained.

[0019]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples. The following parts and% are based on weight.

First, the composition of a common coating solution used in the following examples and comparative examples and the coating method will be described. [Thermochromic layer coating liquid] (Liquid A) 3- (N-cyclohexyl-N-methyl) amino-6-methyl-7-anilinofluorane 20 parts Hydroxyethylcellulose 10% aqueous solution 20 parts Water 60 parts (liquid B) Bisphenol A 10 parts Calcium carbonate 5 parts Stearic acid amide 5 parts Completely saponified polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts Disperse the above liquids A and B in a sand mill so that the average particle diameter becomes 2 μm or less. . (Liquid C) Liquid A 10 parts Liquid B 60 parts 10% aqueous solution of each water-soluble resin shown in Table 1 below 30 parts The above-mentioned mixed solution is stirred and the thermosensitive coloring layer having each water-soluble resin shown in Table 1 is stirred. Obtain a coating solution.

[0021]

[Table 1] This coating solution is applied and dried on a high-quality paper support having a basis weight of 56 g / m ² or on an intermediate layer provided on the high-quality paper support so that the dry adhesion is 6 g / m ^2. A thermosensitive coloring layer having each water-soluble resin shown in Table 1 is formed.

[Intermediate Layer Coating Liquid] (D Liquid) Calcined Kaolin 10 parts Water 90 parts The above composition liquid is dispersed in a sand mill so that the average particle diameter is 2 μm or less to obtain liquid D. (Liquid E) Liquid D 50 parts 10% aqueous resin solution of each type shown in Table 1 10 parts Water 40 parts For coating the intermediate layer having the respective water-soluble resins shown in Table 1 by mixing and dispersing the liquid of the above composition To obtain E liquid. [Protective layer coating liquid] (F liquid) E liquid 30 parts 70% aqueous solution of 10% resin of each type shown in Table 1 70 parts The above composition liquids are mixed and dispersed to form a protective layer having each water-soluble resin shown in Table 1. An F liquid for coating is obtained. Obtained E
The liquid is applied and dried on the thermosensitive coloring layer so that the dry adhesion amount becomes 3 g / m ² , and the protective layer having each water-soluble resin shown in Table 1 is formed. [Backcoat Layer Coating Liquid] (G Liquid) The F liquid is used as a backcoat layer coating G liquid to obtain a backcoat layer coating G liquid having each water-soluble resin shown in Table 1. It is coated on the back surface of a support of high-quality paper having a basis weight of 56 g / m ^{2 so} that the dry adhesion amount is 3 g / m ² to obtain a back coat layer having each water-soluble resin shown in Table 1.

Example 1 The water-soluble resin of the liquid C of the thermosensitive color developing layer coating liquid is shown in Table 1 as N.
o. As the calcium salt of carboxy-modified polyvinyl alcohol of No. 1, a thermosensitive color developing layer coating solution was prepared. This coating solution was applied and dried on a high-quality paper support having a basis weight of 56 g / m ² so that the dry adhesion amount was 6 g / m ² , to prepare a heat-sensitive recording material of Example 1.

Comparative Example 1 In Example 1, the water-soluble resin of the liquid C of the thermosensitive color developing layer coating liquid was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. A heat-sensitive recording material of Comparative Example 1 was prepared in the same manner as in Example 1 except that the completely saponified polyvinyl alcohol of 2 was used.

Comparative Example 2 In Example 1, the water-soluble resin of the liquid C of the thermosensitive color developing layer coating liquid was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. A thermosensitive recording material of Comparative Example 2 was prepared in the same manner as in Example 1 except that the sodium salt of carboxy-modified polyvinyl alcohol of 3 was used.

Comparative Example 3 In Example 1, the water-soluble resin of the C liquid of the thermosensitive color developing layer coating liquid was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. A heat-sensitive recording material of Comparative Example 3 was prepared in the same manner as in Example 1 except that the isobutylene / maleic anhydride copolymer latex of 4 was used.

Comparative Example 4 In Example 1, the water-soluble resin of the solution C of the thermosensitive color developing layer coating solution was added as o. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. A heat-sensitive recording material of Comparative Example 4 was prepared in the same manner as in Example 1 except that methyl cellulose of No. 5 was used.

Example 2 The water-soluble resin of solution C of the thermosensitive color developing layer coating solution was
o. As the completely saponified polyvinyl alcohol of No. 2, a thermosensitive coloring layer coating solution was prepared. The water-soluble resin of the E liquid for coating the intermediate layer was No. 1 in Table 1. As the calcium salt of carboxy-modified polyvinyl alcohol of 1 above, a solution for coating the intermediate layer was prepared. This intermediate layer coating liquid was applied and dried on a commercially available high-quality paper having a basis weight of 56 g / m ^{2 so} that the dry adhesion amount was 4 g / m ² to form an intermediate layer. A thermosensitive recording material of Example 2 was prepared by applying and drying the prepared thermosensitive coloring layer coating liquid on the intermediate layer so that the dry adhesion amount was 6 g / m ² .

COMPARATIVE EXAMPLE 5 In Example 2, the water-soluble resin of the F liquid for coating the intermediate layer was selected from NO. No. 1 instead of the calcium salt of carboxy-modified polyvinyl alcohol. In the same manner as in Example 1 except that the completely saponified polyvinyl alcohol of 2 was used,
A heat sensitive recording material of Comparative Example 5 was prepared.

Comparative Example 6 In Example 2, the water-soluble resin of the E liquid for coating the intermediate layer was No. 1 in Table 1. No. 1 instead of the calcium salt of carboxy-modified polyvinyl alcohol. A thermosensitive recording material of Comparative Example 6 was prepared in the same manner as in Example 2 except that sodium of carboxy-modified polyvinyl alcohol of 3 was used.

Comparative Example 7 In Example 2, the aqueous solution resin of the E liquid for coating the intermediate layer was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. 4 isobutylene /
Example 2 except that a maleic anhydride copolymer latex was used.
A thermal recording material of Comparative Example 7 was prepared in the same manner as in.

Comparative Example 8 In Example 2, the water-soluble resin of the E liquid for coating the intermediate layer was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. A heat-sensitive recording material of Comparative Example 8 was prepared in the same manner as in Example 2 except that methyl cellulose of No. 5 was used.

Example 3 The water-soluble resin of the liquid C of the thermosensitive color developing layer coating liquid was used as N in Table 1.
o. As the completely saponified polyvinyl alcohol of No. 2, a thermosensitive coloring layer coating solution was prepared. The water-soluble resin of the F liquid for coating the protective layer was No. 1 in Table 1. As the calcium salt of carboxy-modified polyvinyl alcohol of 1 above, a liquid for coating the protective layer was prepared. This thermosensitive color-developing layer coating liquid was applied and dried on a commercially available high-quality paper having a basis weight of 56 / m ^{2 so} that the dry adhesion amount was 6 g / m ² to form a thermosensitive color-developing layer. Furthermore, the coating amount for the protective layer prepared on the thermosensitive color-developing layer gives a dry adhesion amount of
The thermosensitive recording material of Example 3 was prepared by coating and drying so as to have g / m ² .

Comparative Example 9 In Example 3, the water-soluble resin of the F liquid for coating the protective layer was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. In the same manner as in Example 1 except that the completely saponified polyvinyl alcohol of 2 was used,
A heat sensitive recording material of Comparative Example 9 was prepared.

Comparative Example 10 In Example 3, the water-soluble resin of the F liquid for coating the protective layer was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. A thermosensitive recording material of Comparative Example 10 was prepared in the same manner as in Example 1 except that the sodium salt of carboxy-modified povinyl alcohol of 3 was used.

Comparative Example 11 In Example 3, the water-soluble resin of the F liquid for coating the protective layer was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. 4 isobutylene /
Example 1 except that a maleic anhydride copolymer latex was used.
A thermal recording material of Comparative Example 11 was prepared in the same manner as in.

Example 4 The water-soluble resin of solution C of the thermosensitive color developing layer coating solution was
o. As the completely saponified polyvinyl alcohol of No. 2, a thermosensitive coloring layer coating solution was prepared. G for coating the back coat layer
The water-soluble resin of the liquid is No. 1 in Table 1. A backcoat layer coating solution was prepared as the calcium salt of carboxy-modified polyvinyl alcohol of 1. This back coating layer coating liquid has a dry adhesion amount of 3 g on a commercially available high-quality paper having a basis weight of 56 g / m ^2.
By coating and drying so as to / m ^2, to form a back coat layer. Further, on the support on the opposite side of the back coat layer, the prepared thermosensitive color developing layer coating solution was applied and dried to give a dry adhesion amount of 6 g / m ^2, and Example 4
A heat-sensitive recording material was prepared.

Comparative Example 13 The water-soluble resin of the G liquid for coating the backcoat layer in Example 4 was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. A thermosensitive recording material of Comparative Example 13 was prepared in the same manner as in Example 4 except that the completely saponified polyvinyl alcohol of 2 was used.

Comparative Example 14 In Example 4, the water-soluble resin of the G liquid for coating the backcoat layer was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. A thermosensitive recording material of Comparative Example 14 was prepared in the same manner as in Example 4 except that the sodium salt of carboxy-modified polyvinyl alcohol of 3 was used.

Comparative Example 15 In Example 4, the water-soluble resin of the G liquid for coating the backcoat layer was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. A heat-sensitive recording material of Comparative Example 15 was prepared in the same manner as in Example 4 except that the isobutylene / maleic anhydride copolymer latex of 4 was used.

Comparative Example 16 In Example 4, the water-soluble resin of the G liquid for coating the back coat layer was No. 1 in Table 1. No. 1 in place of the calcium salt of carboxy-modified polyvinyl alcohol. A thermosensitive recording material of Comparative Example 15 was prepared in the same manner as in Example 4 except that methyl cellulose of No. 5 was used.

The performance of the thermal recording materials obtained in the above Examples and Comparative Examples was evaluated by the following method. The results are shown in Table 2. (1) Dynamic sensitivity Using a thermal printing device equipped with a thermal head manufactured by Matsushita Electronic Parts Co., Ltd., a head voltage of 24 V and a printing energy of 0.45
Printing was performed under the conditions of W / dot and pulse width of 0.1 to 1.2 msec, the printing energy when the density became 1.0 was calculated by a Macbeth densitometer, and the numerical value of Example 1 was set as 1 as a relative value. The ratio is shown (the larger the relative value, the better the sensitivity). (2) Plasticizer resistance After printing with a heat block at 150 ° C., 1 drop of plasticizer dioctyl adipate (DOA) was placed on the printed area and 2
After 5 minutes, wipe and measure the remaining rate of print density (larger is better). (3) Water resistance test After printing with a heat block at 150 ° C., dip in water at 20 ° C. for 10 hours and take out, and measure the residual rate of print density (the higher the residual rate, the better). (4) Water peeling resistance The thermosensitive recording material is immersed in water at 20 ° C. for 10 hours, taken out, and rubbed with a clock meter 10 times to observe the presence or absence of surface peeling. ◯: No peeling ×: Peeling (5) Head matching property Change of the printed image was performed by using the Matsushita thermal printer under the conditions of head voltage of 24 V, printing energy of 0.45 W / dot and pulse width of 1 msec. To observe. Amount of adhering head shavings ○: There is no blurring of the printed image due to the adhering of the head shavings, there is no white spot in the printed image due to the head being cut, Δ: No white spots in the printing image due to the head being cut off, but there is a shading of the printed image due to the adherence of head shavings × A large amount of print image blurring due to head dust adherence,
There is a blank area in the printed image due to the head being cut.

[0043]

[Table 2] Note: -is not evaluated, and the measurement result in () is the evaluation of the back coat surface.

[0044]

The thermosensitive recording material of the present invention uses the calcium salt of carboxy-modified polyvinyl alcohol in the thermosensitive coloring layer, the protective layer, the intermediate layer, or the backcoat layer. It shows remarkably excellent properties in terms of storage stability such as water peeling resistance, print smearing due to dust deposits on the thermal head, and head matching properties such as printing defects due to the thermal head due to electrolytic corrosion.

Claims (4)

[Claims] 1. A heat-sensitive recording material comprising a support and a heat-sensitive color-forming layer containing a leuco dye and a color developer as main components.
A heat-sensitive recording material comprising a calcium salt of carboxy-modified polyvinyl alcohol in the heat-sensitive color developing layer. 2. A thermosensitive coloring layer containing a leuco dye and a color developer as main components is provided on a support, and a protective layer containing a calcium salt of carboxy-modified polyvinyl alcohol as a main component is further provided on the thermosensitive coloring layer. A heat-sensitive recording material characterized by: 3. An intermediate layer comprising a calcium salt of carboxy-modified polyvinyl alcohol as a main component is provided on a support,
Further, a thermosensitive recording material comprising a thermosensitive coloring layer containing a leuco dye and a color developer as main components. 4. A heat-sensitive recording material comprising a back coat layer containing a calcium salt of carboxy-modified polyvinyl alcohol as a main component on the back surface of the support (the surface having the heat-sensitive color forming layer as the front surface).