JPH10226162A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording material having good blocking resistance in which a rewetting paste layer keeps adhesion. SOLUTION: In a thermal recording material in which a thermal recording layer and a protective layer are formed on one side of a support in sequence and a rewetting paste layer is formed on the other side, the first rewetting paste layer containing rewetting paste as a main component and the second rewetting paste layer containing a lubricant and rewetting paste as main components are formed on the opposite side of the support in sequence as the rewetting paste layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material which can be stuck with a rewet adhesive, and more particularly to a heat-sensitive recording material which does not block even in a wound state.

[0002]

2. Description of the Related Art A thermosensitive recording medium in which a plurality of coloring compounds are brought into contact with heat to obtain a recorded image is well known. Such a thermosensitive recording medium is relatively inexpensive, has a compact recording device, and is easy to maintain. Therefore, it is used not only as a recording medium for facsimile machines and various computers but also in a wide range of fields.

[0003] In recent years, the field of application has expanded, for example, as a recording medium for labels, a pressure-sensitive adhesive layer,
Alternatively, there is a thermal recording medium provided with a rewet adhesive layer. As one of the uses of the thermal recording medium with a rewet adhesive layer on the back side,
There is a thermal recording medium for postal stamps. The postal stamp paper heat-sensitive recording material is used by recording the name of a post office, shipping date, postage, and the like on the heat-sensitive recording surface, and then wetting the back surface with water to directly attach the postal matter to mail.

A thermosensitive recording material for a postal stamp is usually stored in a roll or wound in a recording device or loaded in a recording device. Under high humidity, the rewet adhesive layer on the back surface and the surface of the thermosensitive recording material adhere to each other. There is a possibility that the heat-sensitive recording medium becomes unusable due to sticking, so-called blocking. As a method for preventing such blocking, the inclusion of a higher fatty acid metal salt in the protective layer is described in JP-A-63-80160. Although described in JP-A-6-79560, further improvement is desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording medium having a rewet adhesive layer on the back side, which has a small decrease in the adhesive force of the rewet adhesive layer and has excellent heat resistance which is excellent in blocking resistance. To provide a recording medium.

[0006]

SUMMARY OF THE INVENTION The above-mentioned object is achieved by a heat-sensitive recording medium in which a heat-sensitive recording layer and a protective layer are sequentially provided on one side of a support and a rewet adhesive layer is provided on the opposite side of the support. As one means for achieving this, the present invention provides, as a rewet adhesive layer, a first rewet adhesive layer containing a rewet adhesive as a main component, and a lubricant and a rewet adhesive as a main component. The second rewet adhesive layer is sequentially provided on the opposite surface of the support.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a heat-sensitive recording medium in which a heat-sensitive recording layer and a protective layer are sequentially provided on one side of a support, and a rewet adhesive layer is provided on the opposite side of the support. The glue layer is a layer sequentially formed from a first rewet glue layer containing a rewet glue as a main component, and a second rewet glue layer containing a lubricant and a rewet glue as a main component. Characterized in that, by including a lubricant in the second rewet glue layer,
The adhesive strength as the rewet adhesive layer is little reduced, and an effect with excellent blocking resistance is obtained. The water content of each rewet paste layer is preferably about 3 to 10%.

The content of the lubricant in the second rewet paste layer is not particularly limited, but is preferably about 1 to 10% by weight based on the total solid content of the second rewet paste layer. When the content of the lubricant is less than 1% by weight, the blocking resistance decreases,
If it exceeds 10% by weight, the adhesive strength may decrease, and 2
About 8% by weight is particularly preferable.

Specific examples of the lubricant contained in the second rewetable adhesive layer include, for example, various phosphoric esters of higher fatty acids such as aluminum monostearyl phosphate, aluminum dioctyl phosphate and aluminum trilauryl phosphate. Polyvalent metal salts of higher fatty acids such as valent metal salts, calcium stearate, zinc stearate, and aluminum stearate; and waxes such as polyethylene wax and paraffin wax.
The average particle size of such a lubricant is about 1 to 10 μm.

[0010] Further, the pigment is contained in the second rewetable glue layer in an amount of 5 to 50% by weight based on the total solid content of the second rewetable glue layer, so that the adhesive strength of the rewetable glue layer is reduced. And the coating properties of the coating solution for forming the second rewetting paste layer are further improved. When the amount is less than 5% by weight, the drying property of the coating liquid for the second rewetable adhesive layer is not improved, and when it exceeds 50%, the adhesive strength as the rewetable adhesive layer may decrease, and 10 to 40% by weight. % Is particularly preferable.

Specific examples of the pigment contained in the second rewet paste layer include, for example, calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, aluminum hydroxide, barium sulfate, talc, kaolin, clay, calcined kaolin,
Examples include amorphous silica, urea / formalin resin filler, and raw starch particles. Among them, aluminum hydroxide is preferable since it does not decrease the adhesive strength. The average particle diameter of the pigment is about 0.5 to 15 μm, particularly 3 to 10 μm
The degree is excellent in blocking resistance and preferable.

The first rewetable glue layer is a layer containing rewetable glue as a main component. The first rewetable glue layer further contains about 5 to 50% by weight of the above pigment. The adhesive strength of the rewet adhesive layer is less reduced, and the blocking resistance and the coating properties of the coating liquid are improved.

The rewet glue used for each rewet glue layer is not required to have adhesiveness during storage, but may be adhesive which is wetted with water. Generally, the adhesive strength of the thermosensitive recording medium is preferably 40 g or more per 1 cm width of the kraft paper so that the thermosensitive recording medium does not peel off when attached to an envelope made of kraft paper and mailed.

Various water-soluble polymers are used as the rewetting paste. Specific examples of the water-soluble polymer include:
For example, fully (partially) saponified polyvinyl alcohol, starch, dextrin, gum arabic, glue, polyacrylamide, styrene-maleic anhydride copolymer salt,
Ethylene-maleic anhydride copolymer salt, vinyl acetate
Salts of an acrylic acid copolymer, salts of a vinyl acetate-methacrylic acid copolymer and the like can be mentioned. Among them, partially saponified polyvinyl alcohol is preferred.

The blocking is improved by using various water-dispersible resins as auxiliary pressure-sensitive adhesives in each rewet adhesive layer. Specific examples of such a water-dispersible resin include, for example, polyvinyl acetate latex, vinyl acetate-ethylene copolymer latex, vinyl acetate-acrylic acid copolymer latex, vinyl acetate-methacrylic acid copolymer latex vinyl acetate-vinyl chloride copolymer Polymer latex, vinyl acetate-versatic acid copolymer latex and the like can be mentioned. The use ratio of the rewet adhesive and the auxiliary pressure-sensitive adhesive is not particularly limited, but 30 to 2 parts by weight based on 100 parts by weight of the rewet adhesive.
It is 50 parts by weight, preferably about 50 to 200 parts by weight.

Above all, when polyvinyl acetate latex as an auxiliary pressure-sensitive adhesive is used together with partially saponified polyvinyl alcohol as a rewet adhesive, a rewet adhesive layer having little blocking and excellent adhesive strength can be obtained. Can be Such partially saponified polyvinyl alcohol has a degree of saponification of about 80 to 95 mol% and a degree of polymerization of 30.
It is about 0 to 2500.

Each rewet paste layer is prepared by mixing a rewet paste aqueous solution and, if necessary, a pigment with a rewet paste solution using water as a medium, the first rewet paste layer coating solution, and a rewet paste. The coating solution for the second rewet adhesive layer obtained by mixing and stirring the aqueous solution, the lubricant and, if necessary, the pigment is formed on the opposite surface of the support by successively applying and drying. Further, a surfactant, an antifoaming agent and the like can be added to each rewetting paste layer.

Examples of the thermal recording system to which the present invention is applied include a combination of a leuco dye and a color former, a combination of a diazonium salt and a coupler, a combination of a transition element such as iron, copper, cobalt and a chelate compound, Combinations of a group III isocyanate compound and an imino compound are exemplified, but a combination of a leuco dye and a color former is preferably used because it is excellent in color density and also excellent in storability of a background portion and a recorded image. Hereinafter, the thermosensitive recording medium combining the leuco dye and the color former will be described in more detail.

As the leuco dye, various known colorless or pale leuco dyes can be used.
-Bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl)-
6-dimethylaminophthalide, 3-diethylamino-7
Blue developing dyes such as -dibenzylamino-benzo [a] fluoran, 3- (N-ethyl-Np-tolyl) amino-7-N-methylanilinofluoran, 3-diethylamino-7-anilino Green coloring dyes such as fluoran and 3-diethylamino-7-dibenzylaminofluoran, and 3,6-bis (diethylamino) fluoran-γ-
Anilinolactam, 3-cyclohexylamino-6-chlorofluoran, 3-dibutylamino-6-methyl-7
-Bromofluorane, 3-diethylamino-7-methylfluoran, 3-diethylamino-7-chlorofluorane, rhodamine (o-chloroanilino) lactam, 3-
Red-coloring dyes such as diethylamino-6,8-dimethylfluoran,

3- (N-methyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3-dimethylamino-6-methyl-7-anilinofluoran, 3-
Diethylamino-6-methyl-7-anilinofluoran, 3-di (n-butyl) amino-6-methyl-7-anilinofluoran, 3-di (n-butyl) amino-7-
(O-chloroanilino) fluoran, 3-diethylamino-7- (o-fluoroanilino) fluoran, 3-di (n-butyl) amino-7- (o-fluoroanilino)
Fluoran, 3- (N-ethyl-p-toluidino) -6
-Methyl-7-anilinofluoran, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-
7-anilinofluoran, 3-diethylamino-6-methyl-7-p-ethoxyanilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7- Anilino fluoran, 2,
2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,
Black-color-forming dyes such as 9′-xanthen-2′-ylamino] phenyl} propane;

3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-
2-yl] -4,5,6,7-tetrachlorophthalide,
3,3-bis [1- (4-methoxyphenyl) -1-
(4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrachlorophthalide, 3-p- (p
-Dimethylaminoanilino) anilino-6-methyl-7
-Chlorofluoran, 3-p- (p-chloroanilino)
Anilino-6-methyl-7-chlorofluoran, 3,6
-Bis (dimethylamino) fluorene-9-spiro-
Leuco dyes having an absorption wavelength in the near infrared region such as 3 ′-(6′-dimethylamino) phthalide are exemplified.
Of course, the present invention is not limited to these, and two or more of them can be used in combination as needed. The leuco dye is desirably about 5 to 40% by weight of the total solid content of the heat-sensitive recording layer.

Among them, in consideration of the use for postal stamps, it is preferable to use one selected from red-coloring dyes capable of producing a vermilion color, or to use a mixture of two or more. Considering the use as a substitute for various stamps, not only black coloring dyes but also green coloring dyes are preferably used.

Various known colorants can be used as the colorant used in combination with the leuco dye as described above. Examples of such a color former include 4,4′-isopropylidene diphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, benzyl 4-hydroxybenzoate, 4,4′-dihydroxydiphenyl sulfone,
4′-dihydroxydiphenyl sulfone, 4-hydroxy-4′-isopropoxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone,
-Hydroxy-4'-methyldiphenylsulfone, 4-
Hydroxyphenyl-4′-benzyloxyphenylsulfone, 3,4-dihydroxyphenyl-4′-methylphenylsulfone, 1,4-bis [α-methyl-α-
(4'-hydroxyphenyl) ethyl] benzene, 1,
Phenolic compounds such as 3-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene;
Thiourea compounds such as N'-di-m-chlorophenylthiourea, N- (p-tolylsulfonyl) carbamoyl-p-benzyloxyphenyl ester, 4,4'-
Bis (Np-tolylsulfonylaminocarbonylamino) diphenylmethane, N- (p-tolylsulfonyl)
-N '- (p-tolyl) -SO ₂ N in the molecule such as urea
Having an H-bond, zinc p-chlorobenzoate,
[2- (p-methoxyphenoxy) ethyloxy] zinc salicylate, 4- [3- (p-tolylsulfonyl) propyloxy] zinc salicylate, 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] zinc salicylate, etc. And a zinc salt of an aromatic carboxylic acid.

The ratio of the leuco dye to the colorant is appropriately selected according to the type of the leuco dye and the colorant used, and is not particularly limited. 1 to 10 parts by weight, preferably 2 to
About 5 parts by weight of a coloring agent is used.

The heat-sensitive recording layer generally uses water as a dispersion medium,
After dispersing the leuco dye and the color former together or separately with a stirring / pulverizer such as a ball mill, attritor, or sand mill, a coating solution for a heat-sensitive recording layer prepared by adding an adhesive or the like is placed on a support. It is formed by coating and drying.

Examples of the adhesive include starch, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, diisobutylene. Maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, urea resin, melamine resin, amide resin, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer A polymer latex, an acrylic resin latex, a polyester polyurethane ionomer, a polyether polyurethane ionomer, etc. are used in an amount of 5% based on the total solid content of the heat-sensitive recording layer coating solution.
About 30% by weight.

Various auxiliaries can be added to the coating solution for the heat-sensitive recording layer, if necessary, such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, and fatty acid metal salts. Dispersants such as zinc stearate,
Waxes such as calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, pigments such as kaolin, clay, calcium carbonate, calcined kaolin, titanium oxide, diatomaceous earth, amorphous silica, activated clay, aluminum hydroxide, etc., and water resistance Agents, antifoaming agents, coloring dyes, sensitizers, preservative improvers and the like.

Specific examples of the sensitizer include, for example, stearic acid amide, N-methylol stearic acid amide, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, 2-naphthylbenzyl ether, m-terphenyl, dibenzyl oxalate , Di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate, p-benzylbiphenyl, p-tolylbiphenyl ether, di (p-
Methoxyphenoxyethyl) ether, 1,2-di (3
-Methylphenoxy) ethane, 1,2-di (4-methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ethane, 1,2-di (4-chlorophenoxy) ethane, 1,2-di Phenoxyethane, 1- (4-methoxyphenoxy) -2- (3-methylphenoxy) ethane, 1,4-di (phenylthio) butane, p-acetotoluidide, p-acetophenethidide, N-acetoacetyl-p- Toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1
-Isopropylphenyl-2-phenylethane and the like.

Specific examples of the preservability improver include, for example, 2,2'-methylenebis (4-methyl-6-tert-butylphenol) and 2,2'-ethylidenebis (4,6-
Di-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4
-Hydroxy-5-tert-butylphenyl) butane;
4,4′-thiobis (3-methylphenol), 2,2
-Bis (4-hydroxy-3,5-dimethylphenyl)
Hindered phenol compounds such as propane, 1,4-
Diglycidyloxybenzene, 4,4'-diglycidyloxydiphenylsulfone, 4-benzyloxy-4 '
Epoxy compounds such as-(2-methylglycidyloxy) diphenyl sulfone, phenol novolak type epoxy resin, bisphenol A type epoxy resin, N, N '
-Di-2-naphthyl-p-phenylenediamine, 2,
Examples thereof include sodium or polyvalent metal salts of 2'-methylenebis (4,6-di-tert-butylphenyl) phosphate, bis (4-ethyleneiminocarbonylaminophenyl) methane, and the like.

The amounts of these sensitizers and preservability improvers are not particularly limited, but are generally preferably adjusted to 4 parts by weight or less with respect to 1 part by weight of the color former.

For the protective layer formed on the heat-sensitive recording layer, a water-soluble polymer having a film-forming property or a water-dispersible resin is used. Specific examples of such a water-soluble polymer or water-dispersible resin include, for example, starches, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, gum arabic, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, and carboxy-modified polyvinyl. Alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer Water-soluble polymers such as coalesced salts, urea resins, melamine resins, amide resins, styrene / butadiene copolymer latex, acrylic resin latex, polyester polyurethane ionomer, poly Such as water-dispersible resins such as chromatography ether polyurethane ionomers.

It is also possible to add pigments to the protective layer. Examples of such pigments include calcium carbonate, zinc oxide, titanium dioxide, amorphous silica, aluminum hydroxide, barium sulfate, talc, kaolin, Examples include clay, calcined kaolin, and urea / formalin resin filler. The amount used is 40 to 90 with respect to the protective layer.
% By weight.

Further, various additives may be used in the protective layer. Examples of such additives include lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax; surfactants (dispersant, wetting agent) such as sodium dioctyl sulfosuccinate; glutaraldehyde; formalin; Glyoxal, dialdehyde starch, polyamide epichlorohydrin resin, boric acid,
Waterproofing agents such as borax, defoamers, fluorescent dyes, coloring dyes and the like can be mentioned. In particular, by using a lubricant and a waterproofing agent together in the protective layer, the blocking resistance is further improved.

The method for forming the first rewet glue layer, the second rewet glue layer, the heat-sensitive recording layer and the protective layer is not particularly limited. For example, a coating solution for forming each layer is coated with an air knife, a burr or the like. It is formed by applying and drying by an application method such as bar blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, die coating, and gravure coating.

The order of forming each layer is not particularly limited. For example, a heat-sensitive recording layer and a protective layer are sequentially formed by coating and drying a coating solution for a heat-sensitive recording layer and a coating solution for a protective layer on one surface of a support. The coating liquid for the first rewet adhesive layer and the coating liquid for the second rewet adhesive layer are applied to the opposite surface of the support and dried to form the first rewet adhesive layer.
A rewet paste layer and a second rewet paste layer are sequentially formed.

The first rewet glue layer has a solid content of 5 to 2
5 g / m ² is preferably about 5 to 15 g / m ^2. The second rewet paste layer has a solid content of about 1 to 8 g / m ² . The second solid amount of rewet adhesive layer blocking resistance is lowered when less than 1 g / m ^2, also there is a possibility that the adhesive force decreases when it exceeds 8 g / m ^2, about 1 to 5 g / m ² is More preferred. The heat-sensitive recording layer has a solid content of 2 to 12
g / m ^2, preferably 3 to 10 g / m ² approximately, 0.1 to 10 g / m ² in solid weight as a protective layer, preferably 0.
It is about 5 to 6 g / m ² .

The support is appropriately selected from neutral or acidic high-quality paper, plastic film, synthetic paper, nonwoven fabric and the like. Further, an intermediate layer containing an organic or inorganic oil-absorbing pigment as a main component may be provided between the support and the heat-sensitive recording layer to improve recording sensitivity and recording image quality.

Incidentally, if necessary, an intermediate layer having excellent heat insulating properties can be provided between the support and the heat-sensitive recording layer to increase the recording sensitivity. In addition, various known techniques in the field of heat-sensitive recording medium production can be added as necessary, such as performing a smoothing treatment such as super calendaring after coating each layer.

[0039]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is by no means restricted to such specific Examples. Parts and% in Examples are parts by weight and% by weight, respectively, unless otherwise specified.

Example 1 (1) Preparation of Coating Solution for Intermediate Layer 100 parts of calcined clay (trade name: Ansilex, manufactured by EMC, oil absorption 110 ml / 100 g), 100 parts of a 10% aqueous solution of polyvinyl alcohol and 200 parts of water Was mixed and stirred to obtain a coating liquid for an intermediate layer.

(2) Preparation of Solution A 3-Diethylamino-6,8-dimethylfluoran 5
Parts, 3-diethylamino-7-chlorofluorane 5 parts,
A composition consisting of 5 parts of a 5% aqueous solution of methylcellulose and 40 parts of water was pulverized with a sand mill until the average particle diameter became 2 μm to obtain a liquid A.

(3) Preparation of Solution B A composition comprising 30 parts of 4-hydroxy-4'-isopropoxydiphenylsulfone, 5 parts of a 5% aqueous solution of methylcellulose and 80 parts of water was sand-milled to have an average particle diameter of 2 parts.
The solution B was obtained by pulverizing the mixture to a thickness of μm.

(4) Preparation of Solution C A composition comprising 20 parts of 1,2-di (3-methylphenoxy) ethane, 5 parts of a 5% aqueous solution of methylcellulose and 55 parts of water was subjected to sand milling until the average particle diameter became 2 μm. It was pulverized to obtain a liquid C.

(5) Preparation of coating solution for heat-sensitive recording layer 55 parts of solution A, 115 parts of solution B, 80 parts of solution C, 80 parts of a 10% aqueous solution of polyvinyl alcohol and calcium carbonate 3
The composition comprising 5 parts was mixed and stirred to obtain a coating solution for a heat-sensitive recording layer.

(6) Preparation of coating liquid for protective layer 60% slurry of kaolin [average particle diameter 0.8 μm] 1
00 parts, 300 parts of a 10% aqueous solution of acetoacetyl group-modified polyvinyl alcohol [trade name: Gosefimer Z-200, manufactured by Nippon Synthetic Chemical Industry], 5 parts of a 10% aqueous solution of glyoxal, and a 30% dispersion of zinc stearate 6
Parts and 140 parts of water were mixed and stirred to obtain a coating liquid for a protective layer.

(7) Preparation of Coating Solution for First Rewetting Paste Layer Partially saponified polyvinyl alcohol [trade name: PVA-2]
17, manufactured by Kuraray Co., Ltd.) and a composition comprising 100 parts of a 10% aqueous solution of aluminum hydroxide [average particle diameter 8 μm] and 10 parts of a 50% aqueous dispersion were mixed and stirred to prepare a coating liquid for the first rewet adhesive layer. Obtained.

(8) Preparation of coating liquid for second rewetting paste layer Partially saponified polyvinyl alcohol [trade name: PVA-2]
17, manufactured by Kuraray Co., Ltd.), a mixture of 120 parts of a 10% aqueous solution, 6 parts of a 50% aqueous dispersion of aluminum hydroxide [average particle diameter 8 μm] and 2 parts of a 30% dispersion of calcium stearate was mixed and stirred. 2 A coating liquid for a rewetting paste layer was obtained.

(9) Preparation of heat-sensitive recording medium Neutral paper-made basis weight 64 g / m^TwoOn one side of high quality paper
Coating solution for undercoat layer, coating solution for heat-sensitive recording layer and for protective layer
The coating amount after drying the coating liquid is 9 g / m^Two, 5g / m ^Two, 3g
/ M^TwoCoated and dried so that the undercoat layer and heat-sensitive recording layer
And protective layers are sequentially formed (after forming each layer,
A smoothing process by a calender was performed. ), The fine paper
The coating liquid for the first re-wetting paste layer and the second re-wetting
The coating amount after drying the coating liquid for the wettable glue layer is 7 g / m^Two, 3g /
m^TwoThe first re-wettable glue layer and the first
(2) A roll-shaped heat-sensitive recording material is obtained by sequentially forming a rewetting paste layer.
Was.

Example 2 In the preparation of the coating liquid for the second rewet adhesive layer of Example 1, 50% of aluminum hydroxide [average particle diameter 8 μm] was used.
A roll-shaped thermosensitive recording medium was obtained in the same manner as in Example 1, except that 6 parts of a 50% dispersion of kaolin (average particle diameter: 1 μm) was used instead of 6 parts of the dispersion.

Example 3 In the preparation of the coating liquid for the second rewetable adhesive layer in Example 1, aluminum hydroxide [average particle diameter] was used instead of 6 parts of a 50% aqueous dispersion of aluminum hydroxide [average particle diameter 8 μm]. 8μ diameter
m] of Example 1 except that 26 parts of a 50% aqueous dispersion was used.
In the same manner as in Example 1, a roll-shaped thermosensitive recording medium was obtained.

Example 4 In the preparation of the coating liquid for the second rewet adhesive layer of Example 1, aluminum hydroxide [average particle diameter] was used instead of 6 parts of a 50% dispersion of aluminum hydroxide [average particle diameter 8 μm]. 8μ
m], except that 1 part of a 50% dispersion was used in the same manner as in Example 1 to obtain a wound thermosensitive recording medium.

Example 5 In the preparation of the coating liquid for the first rewet adhesive layer in Example 1, a partially saponified polyvinyl alcohol [PVA-21] was used.
7, manufactured by Kuraray Co., Ltd.]
Partially saponified polyvinyl alcohol [Product name: PVA20
5, manufactured by Kuraray Co., Ltd.], except that 60 parts of a 10% aqueous solution and 9 parts of a polyvinyl acetate latex having a solid concentration of 45% were used in the same manner as in Example 1 to obtain a wound thermosensitive recording medium.

Example 6 The procedure of Example 1 was repeated except that 7 parts of a 30% calcium stearate dispersion was used instead of 2 parts of a 30% calcium stearate dispersion in the preparation of the second rewet adhesive layer coating solution. In the same manner as in Example 1, a wound thermosensitive recording medium was obtained.

Example 7 In the preparation of the heat-sensitive recording material of Example 1, the coating amount after drying the first rewet adhesive layer coating liquid and the second rewet adhesive layer coating liquid was 7 g / m ² and Instead of coating and drying to 3 g / m ² to form the first rewet adhesive layer and the second rewet adhesive layer, the coating liquid for the first rewet adhesive layer and the second rewet adhesive layer Except for forming the first rewet adhesive layer and the second rewet adhesive layer by applying and drying the layer coating solution so that the coating amount after drying becomes 9.5 g / m ² and 0.5, the first rewet adhesive layer and the second rewet adhesive layer were formed. In the same manner as in Example 1, a wound thermosensitive recording medium was obtained.

Example 8 In the preparation of the thermosensitive recording medium of Example 1, the coating amount after drying the first rewetting adhesive layer coating liquid and the second rewetting adhesive layer coating liquid was 7 g / m ² and Instead of coating and drying to 3 g / m ² to form the first rewet adhesive layer and the second rewet adhesive layer, the coating liquid for the first rewet adhesive layer and the second rewet adhesive layer The coating amount after drying the layer coating solution is 3 g / m ² and 7 g
/ M ^2, and a roll-shaped thermosensitive recording medium was obtained in the same manner as in Example 1 except that the first and second rewet adhesive layers were formed by application and drying to form a first rewet adhesive layer and a second rewet adhesive layer.

Example 9 In the preparation of the coating solution for the first rewet adhesive layer of Example 1, aluminum hydroxide [average particle size] was used instead of 10 parts of a 50% aqueous dispersion of aluminum hydroxide [average particle size 8 μm]. Diameter 8
[μm] was obtained in the same manner as in Example 1 except that 24 parts of a 50% aqueous dispersion was used.

Example 10 In the preparation of the coating solution for the first rewetable adhesive layer in Example 1, aluminum hydroxide [average particle diameter] was used instead of 10 parts of a 50% dispersion of aluminum hydroxide [average particle diameter 8 μm]. 8μ
m], except that 1 part of a 50% dispersion was used in the same manner as in Example 1 to obtain a wound thermosensitive recording medium.

COMPARATIVE EXAMPLE 1 In the preparation of the heat-sensitive recording material of Example 1, the coating amount after drying the first rewet adhesive layer coating liquid and the second rewet adhesive layer coating liquid was 7 g / m ² and Instead of forming the first rewet adhesive layer and the second rewet adhesive layer by applying and drying to an application amount of 3 g / m ² , the coating liquid for the first rewet adhesive layer is applied after drying. A roll-shaped heat-sensitive recording material was obtained in the same manner as in Example 1 except that only the first rewet adhesive layer was formed by coating and drying so that the amount was 10 g / m ² .

COMPARATIVE EXAMPLE 2 In the preparation of the thermosensitive recording medium of Example 1, the coating amount after drying the first rewet adhesive layer coating liquid and the second rewet adhesive layer coating liquid was 7 g / m ² and Instead of forming the first rewetable glue layer and the second rewetable glue layer by coating and drying to 3 g / m ² , the coating amount after drying the second rewetable glue layer coating liquid is applied. A roll-shaped heat-sensitive recording material was obtained in the same manner as in Example 1 except that only the second rewet adhesive layer was formed by coating and drying so as to be 10 g / m ² .

Comparative Example 3 In the same manner as in Example 1 except that 2 parts of water was used instead of 2 parts of the 30% dispersion of calcium stearate in the preparation of the coating liquid for the second rewet adhesive layer in Example 1. To obtain a rolled thermosensitive recording medium.

The following evaluation tests were performed on the thus obtained heat-sensitive recording medium, and the results are shown in Table 1. [Recording density] Applied energy 0.45 mJ / d using a thermal recording evaluation machine [TM-PMD type, manufactured by Okura Electric Co., Ltd.]
The recording was performed at ot, and the density of the obtained recorded image was measured in a visual mode using a Macbeth densitometer (RD-914, manufactured by Macbeth).

[Adhesive Strength of Rewettable Glue Layer] The obtained heat-sensitive recording material was formed into a strip having a width of 1 cm, water was adhered to the back surface, and the resultant was adhered to kraft paper. After 10 seconds, the adhesive force was measured.

[Blocking Resistance] As a method for evaluating the blocking resistance of the wound thermosensitive recording medium, five sheets of the obtained thermosensitive recording medium were stacked and pressed from above with a pressure of 200 g / cm ² to obtain a recording medium of 40 mm. It was left for 3 days in an environment of 90 ° C. and 90% RH, and the blocking resistance between the protective layer surface and the removable adhesive layer surface was evaluated as follows. Evaluation criteria ★: There is no adhesion between the protective layer surface and the removable glue layer surface. A: Slight adhesion between the protective layer surface and the removable adhesive layer surface. ：: A small amount of adhesion occurs between the protective layer surface and the removable adhesive layer surface, but it can be easily peeled. Δ: Adhesion occurs between the protective layer surface and the removable adhesive layer surface, but it cannot be easily peeled. X: Adhesion between the protective layer surface and the removable adhesive layer surface occurred, and peeling was not possible.

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[Table 1]

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As is clear from the results shown in Table 1, the heat-sensitive recording material of the present invention has a small decrease in the adhesive force of the rewet adhesive layer and has excellent blocking resistance.

Claims (5)

[Claims] 1. A heat-sensitive recording medium comprising a support, in which a heat-sensitive recording layer and a protective layer are sequentially provided on one side, and a rewet adhesive layer on the opposite side of the support, wherein the rewet adhesive layer is rewet. And a second rewet adhesive layer containing a lubricant and a rewet adhesive as a main component in that order. Thermal recording medium. 2. The heat-sensitive recording material according to claim 1, wherein the amount of the lubricant is 1 to 10% by weight based on the total solid content of the second rewetable adhesive layer. 3. The method according to claim 1, further comprising adding 5 to 5 pigments to the second rewet paste layer.
3. The thermosensitive recording medium according to claim 1, wherein said thermosensitive recording medium contains 0% by weight. 4. The solid content of the second rewet paste layer is 1 to 5 g / g.
The heat-sensitive recording material according to any one of claims 1 to 3 is m ^2. 5. The method according to claim 1, further comprising adding 5 to 5 pigments to the first rewet paste layer.
The thermosensitive recording medium according to any one of claims 1 to 4, wherein the thermosensitive recording medium contains 0% by weight.