JPH10100537A - Adhesive sheet for thermal recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a decrease of color developing power of a thermal recording layer under high temperature and high moisture conditions by incorporating emulsion polymerized styrene butadiene copolymer in a barrier layer in an adhesive sheet for thermal recording in which the recording layer, barrier layer and a release layer are sequentially provided on one surface side of a support and an adhesive layer is provided on the rear surface side. SOLUTION: In the adhesive sheet for thermal recording having excellent recording suitability without decrease of color developing power even in the case of using under severe conditions such as application to distribution management, a thermal recording layer, a barrier layer and a release layer are sequentially provided on one surface side of a support, while an adhesive layer is provided on the rear surface side. Emulsion polymerized styrene butadiene copolymer is contained in the barrier layer. The copolymer which has a glass transition point of a range of -20 to 20 deg.C is used. The content of the copolymer in the barrier layer is 20wt.% or more or preferably 30wt.% or more.

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 pressure-sensitive adhesive sheet, and more particularly to a heat-sensitive recording pressure-sensitive adhesive sheet suitable for distribution management.

[0002]

2. Description of the Related Art A thermosensitive recording medium in which a recording image is obtained by contacting a plurality of coloring substances with heat is well known.
As described above, the thermosensitive recording medium is relatively inexpensive, the recording apparatus is compact, and the maintenance thereof is easy. Therefore, the thermosensitive recording medium is used in recording media such as facsimile machines and various computers, and in a wide variety of fields. One of the fields of use is, for example, a heat-sensitive recording adhesive sheet or a heat-sensitive recording tag for a POS (point of sales) system.

Further, with the recent development of information processing technology and the performance of recording equipment, it has become possible to perform recording on a heat-sensitive recording adhesive sheet at a higher speed than in the past, but an adhesive layer is provided on the back side of these adhesive sheets. A release paper is attached for the purpose of protection, the diameter of the heat-sensitive recording pressure-sensitive adhesive sheet is increased, and the size of the heat-sensitive recording pressure-sensitive adhesive sheet that can be loaded into a recording device is limited. The number of pressure-sensitive adhesive sheets that can be issued is reduced, and the recording pressure-sensitive adhesive sheet must be frequently replaced with a higher recording speed. In addition, the treatment of the release paper generated at this time is also a problem, and the cost of the release sheet in the recording adhesive sheet is not small in terms of cost.

A heat-sensitive recording pressure-sensitive adhesive sheet using no release paper is disclosed in JP-A-60-54842 and JP-A-1-28058.
4, JP-A-2-165899, JP-A-5-
It is proposed in Japanese Patent No. 8541 or Japanese Patent Application Laid-Open No. 6-222717. However, since the surface of the recording layer and the surface of the pressure-sensitive adhesive layer are in contact with the roll of the heat-sensitive recording pressure-sensitive adhesive sheet without using release paper, the components of the pressure-sensitive adhesive are recorded from the surface of the recording layer when exposed to high temperature and high humidity conditions. There is a drawback that the coloring ability is reduced due to penetration into the layer.

[0005] For this reason, there is no problem even when used under severe conditions such as distribution management, it can be adapted to high-speed printing, there is no decrease in coloring ability, it is excellent in recording suitability, and it is cost effective. However, there is a strong demand for an advantageous heat-sensitive recording adhesive sheet.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording layer which does not cause a decrease in the coloring ability even under high temperature and high humidity conditions, can be adapted to high-speed printing, is excellent in recording suitability, and has a low cost. An object of the present invention is to provide a heat-sensitive recording pressure-sensitive adhesive sheet suitable for advantageous distribution management use.

[0007]

The above object is achieved by a heat-sensitive recording pressure-sensitive adhesive sheet in which a heat-sensitive recording layer, a barrier layer, and a release layer are sequentially provided on one side of a support and a pressure-sensitive adhesive layer is provided on the back side. As one means for achieving this, the present invention includes an emulsion-polymerized styrene-butadiene copolymer in the barrier layer.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The emulsion-polymerized styrene-butadiene copolymer contained in the barrier layer is mainly composed of styrene and butadiene. Acid, (meth) acrylate,
Acrylamide, acrylonitrile and the like can be included as a styrene-butadiene copolymer component.

The barrier property of the barrier layer with respect to the pressure-sensitive adhesive in the pressure-sensitive adhesive layer is preferably such that the Tg of the emulsion-polymerized styrene-butadiene copolymer is relatively high, and the adhesion between the barrier layer and the release layer is Tg. It has been found that a relatively low one is more excellent, but in particular, one having a Tg of -20 to 20 ° C. has been found to be more excellent in the barrier property against the adhesive and the adhesion between the barrier layer and the release layer. .

[0010] The heat-sensitive recording pressure-sensitive adhesive sheet of the present invention is intended to suppress a decrease in the coloring ability of the heat-sensitive recording layer due to the pressure-sensitive adhesive layer.
Alternatively, for the purpose of improving the recording suitability, a barrier layer containing a specific copolymer composed of an emulsion-polymerized styrene-butadiene copolymer is provided on the heat-sensitive recording layer, and the barrier of the specific copolymer is provided. 20% by weight in the layer
Or more, preferably 30% by weight or more.

In the present invention, the barrier layer contains a film-forming emulsion-polymerized styrene-butadiene copolymer, but other film-forming properties may be used as long as the desired effects of the present invention are not impaired. It is also possible to use various known adhesives having in combination, specific examples of such adhesives include, for example, starches, hydroxyethyl cellulose, methyl cellulose,
Carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, siliconic polyvinyl alcohol, diisobutylene-maleic anhydride copolymer salt, styrene-maleic anhydride copolymer salt And ethylene-acrylic acid copolymer salt, styrene-acrylic acid copolymer salt, urea resin, melamine resin, amide resin, polyurethane latex, polyacryl ester latex and the like.

Further, the average particle size in the barrier layer is 0.1 to 3
30 to 70% by weight of a pigment having a thickness of 30 μm based on the total solid content of the barrier layer
The effect of improving the barrier property against the pressure-sensitive adhesive in the pressure-sensitive adhesive layer and the adhesion between the barrier layer and the release layer is improved. If the content of the pigment is less than 30% by weight, the above effect cannot be sufficiently obtained. If the content exceeds 70% by weight, the silicone compound in the coating solution for the release layer penetrates into the barrier layer, thereby impairing the releasability. However, even though the barrier property to the adhesive is improved, the barrier property to the solvent or the plasticizer may be reduced.

Specific examples of such pigments include, for example, calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, amorphous silica, aluminum hydroxide, barium sulfate, talc, kaolin, clay, calcined kaolin, styrene microballs, nylon powder. , Polyethylene powder, urea-formalin resin filler and the like. Among them, the use of kaolin or aluminum hydroxide is preferable because of its high barrier property and small decrease in recording density.

The barrier layer is formed by coating a latex containing an emulsion-polymerized styrene-butadiene copolymer and, if necessary, a pigment and the like with an aqueous coating solution for the barrier layer, coating the heat-sensitive recording layer on the heat-sensitive recording layer, followed by drying. It is formed. Further, a layer containing a water-soluble polymer can be provided between the heat-sensitive recording layer and the barrier layer.

Since the release layer is formed on the barrier layer surface at least after the heat-sensitive recording layer is provided, the release layer is preferably made of an ultraviolet-curable or electron-beam-curable silicone compound as a release agent since thermal curing is unnecessary. Used.

Specific examples of these silicone compounds include a mixture composition of a mercapto group-containing organopolysiloxane and a vinyl group-containing organopolysiloxane, an acrylic group, a methacryl group or a cinnamoyl group-containing organopolysiloxane composition, a maleimide group or a maleimide group. Phenylmaleimide group-containing organopolysiloxane composition, azide group-containing organopolysiloxane and vinyl group-containing organopolysiloxane, thioacryl group, thiomethacryl group or thiocinnamoyl group-containing organopolysiloxane composition, acrylamide group, methacryl An amide group or cinnamoyl amide group-containing organopolysiloxane composition may, for example, be mentioned. Further, a mixed composition of an epoxy group-containing organopolysiloxane utilizing ultraviolet-initiated cationic polymerization and a diazonium Lewis acid salt as a photo-decomposition initiator can also be used. In the case of an ultraviolet curing type, a curing initiator is required. Specific examples of such a curing initiator include benzoyl alkyl ether and its derivatives, acetophenone and its derivatives, thioxanthone and its derivatives, and the like.

For the pressure-sensitive adhesive layer, various known pressure-sensitive adhesives can be used, for example, natural rubber, acrylic resin-based pressure-sensitive adhesive,
And a styrene-isoprene-styrene block copolymer, a two-part crosslinkable acrylic removable pressure-sensitive adhesive, and the like. In particular, by using a two-part crosslinkable acrylic removable adhesive in combination with an appropriate crosslinking agent such as an epoxy derivative, when applied to a support, the crosslinking of the adhesive has not progressed, and to a certain extent Since the adhesive soaks into the support, an adhesive force of the appropriate adhesive to the support is obtained,
Further, as the crosslinking of the pressure-sensitive adhesive progresses with time, the cohesive force increases, and re-peelability is generated. In this type, it is easy to control the adhesive strength and removability by selecting the type of acrylic used and the crosslinking agent.

The thermal recording method to which the present invention is applied includes, for example, 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 and a chelate compound, and a combination of an aromatic isocyanate compound and a chelate compound. Combinations with imino compounds and the like can be mentioned, but a combination of a colorless or light-colored leuco dye and a color former is preferably used because of its excellent color density. Hereinafter, an adhesive sheet for a heat-sensitive recording layer using a leuco dye and a color former will be described in detail. As the colorless or light-colored leuco dye, various known dyes can be used, and examples thereof include the following.

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylamino Phthalide, 3-
(N-ethyl-Np-tolyl) amino-7-N-methylanilinofluoran, 3-diethylamino-7-anilinofluoran, 3-diethylamino-7-dibenzylaminofluoran, 3-cyclohexylamino -6-chlorofluorane, 3-diethylamino-6-methyl-7
-Chlorofluorane, 3-diethylamino-7-chlorofluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-7- (m-trifluoro Methylanilino) fluoran, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3
-Di (n-butyl) amino-6-methyl-7-anilinofluoran, 3-di (n-pentyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-7
-(O-chloroanilino) fluoran, 3-di (n-butyl) amino-7- (o-chloroanilino) fluoran, 3-di (n-butyl) amino-7- (o-fluoroanilino) fluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluoran, 3-
(N-ethyl-N-furfurylamino) -6-methyl-
7-anilinofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3- (N-methyl-N
-N-propylamino) -6-methyl-7-anilinofluoran, 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, 3,6, -bis (dimethylamino) fluorene-9-spiro-3'-
(6′-dimethylamino) phthalide, 3- (N-ethyl-N-2-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran, 3- (4-dimethylamino) anilino-5,7 -Dimethylfluoran and the like. Of course, the present invention is not limited to these, and two or more of them can be used in combination as needed. The amount of the leuco dye used is not particularly limited, but is preferably about 5 to 40% by weight based on the heat-sensitive recording layer.

Various known colorants can be used in combination with the leuco dye, such as hydroquinone monobenzyl ether, 4,4'-isopropylidene diphenol, 1,1-bis (4-hydroxyphenyl). )
Cyclohexane, 4,4'-dihydroxydiphenyl-
2,2-butane, 4,4'-dihydroxydiphenylmethane, 2,2-bis (4-hydroxyphenyl) -4-
Methylpentane, 2,2-bis (4-hydroxyphenyl) heptane, bis (4-hydroxyphenylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 1,3-bis [α-methyl-α- (4 ′
-Hydroxyphenyl) ethyl] benzene, 4,4'-
Dihydroxydiphenyl sulfide, di (4-hydroxy-3-methylphenyl) sulfine, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy- 4'-isopropoxydiphenyl sulfone, 4-hydroxyphenyl-
4′-benzyloxyphenyl sulfone, 4-hydroxy-3 ′, 4′-tetramethylenebiphenyl sulfone,
3,4-dihydroxyphenyl-p-tolylsulfone,
Benzyl 4-hydroxybenzoate, 2,4-dihydroxy-2'-methoxybenzanilide, N, N'-di-m
-Chlorophenylthiourea, zinc 4- [2- (p-methoxyphenoxy) ethyloxy] salicylate, 4- [3
-(P-tolylsulfonyl) propyloxy] zinc salicylate, 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] zinc salicylate, 4,4'-bis (p-
(Tolylsulfonylaminocarbonylamino) diphenylmethane, Np-tolylsulfonyl-N'-phenylurea and the like.

The ratio between the leuco dye and the color former is appropriately selected according to the type of the leuco dye used, and is not particularly limited.
0.5 to 10 parts by weight, preferably 1 to 5 parts by weight per part by weight
Parts by weight are desirable.

If necessary, the heat-sensitive recording layer may contain a sensitizer for increasing the recording sensitivity, or may contain a storability improving agent for improving the storability of the recorded image. Specific examples of such a sensitizer include, for example, stearic acid amide, methylolamide stearic acid, ethylenebisstearic acid amide, dibenzyl oxalate,
Di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate, dimethyl terephthalate, dibenzyl terephthalate, phenyl 1-hydroxynaphthoate, 1,2-di (3-
Methylphenoxy) ethane, 1,2-diphenoxyethane, 1-phenoxy-2-naphthoxyethane, 1-phenoxy-2- (4-methylphenoxy) ethane, 1-
(4-methylphenoxy) -2-naphthoxyethane,
1,3-naphthoxypropane, 1,4-naphthoxybutane, p-benzylbiphenyl, m-terphenyl, benzyl-2-naphthyl ether, 1,2-bis (3,4-
Dimethylphenyl) ethane, 1,4-bis (p-tolyloxy) benzene, diphenylsulfone, diphenyl carbonate, 2- (2′-hydroxy-5′-methylphenyl)
Benzotriazole and the like.

Specific examples of the preservability improver include, for example, 2,2'-methylenebis (4-methyl-6-tert-butylphenol) and 2,2'-ethylenebis (4-methyl-6-tert-butylphenol) 2,2′-ethylidenebis (4,6-di-tert-butylphenol), 2,
2′-ethylidenebis (4-methyl-6-tert-butylphenol), 2,2′-ethylidenebis (4-ethyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-butylphenol) (Hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4)
-Hydroxy-5-tert-butylphenyl) butane;
N, N'-di-2-naphthyl-p-phenylenediamine, sodium 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate, 4,4'-bis (ethyleneiminecarbonylamino) Examples include diphenylmethane, 4-benzyloxy-4 ′-(2-methyl-2,3-epoxypropyloxy) diphenylsulfone, and novolak-type resins. These sensitizers and preservability improvers are used in an amount of about 0.05 to 4 parts by weight based on 1 part by weight of the leuco dye.

The adhesive used for the heat-sensitive recording layer may be any of a water-soluble resin and a water-dispersible resin. For example, completely (partially) saponified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, starch, oxidized starch, gum arabic, gelatin, casein, chitosan, methylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, styrene Water-soluble resins such as salts of acrylic acid copolymers, salts of styrene-maleic anhydride copolymers, salts of methyl vinyl ether-maleic anhydride copolymers, salts of isopropylene-maleic anhydride copolymers, and acetic acid Vinyl latex, acrylate copolymer latex, methacrylate copolymer latex, vinyl acetate- (meth) acrylate copolymer latex, polyurethane latex, poly Vinyl-based latex, polyvinylidene chloride latex, styrene - include water-dispersible resin such as butadiene latex. The amount of the adhesive used is preferably about 5 to 30% by weight based on the heat-sensitive recording layer.

Further, glyoxal,
Dialdehyde compounds such as dialdehyde starch, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins, melamine resins, diglycidyl compounds such as glycerin diglycidyl ether, dimethylol urea compounds, aziridine compounds, blocked isocyanate compounds, Ammonium persulfate, boric acid, borax,
Waterproofing agents such as ferric chloride and magnesium chloride, calcium carbonate, magnesium carbonate, magnesium oxide,
Kaolin, clay, talc, calcined clay, amorphous silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide,
Pigments such as titanium oxide, aluminum hydroxide, barium sulfate, and urea-formal marine resin filler; surfactants such as acetylene glycol, sodium dialkyl sulfosuccinate, and sodium alkylbenzene sulfonate;
Lubricants such as zinc stearate and calcium stearate, waxes such as polyethylene wax, carnauba wax, paraffin wax and ester wax, and coloring dyes and fluorescent dyes can also be added.

The heat-sensitive recording layer generally uses water as a dispersion medium,
Stirring with a ball mill, attritor, sand mill, etc., a pulverizer, a leuco dye, a color former, and if necessary, a sensitizer and a storage improver together or separately with a dispersant together with a dispersant have a volume average particle diameter of 0.3 to 3 μm. After finely dispersing to a degree, a coating solution for a heat-sensitive recording layer prepared by adding an adhesive while mixing and stirring is applied onto one surface of a support and dried.

The method of forming the heat-sensitive recording layer and the barrier layer is not particularly limited. For example, an appropriate method such as air knife coating, variver blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, die coating, etc. After the coating liquid for the heat-sensitive recording layer is coated on the support by a coating method and dried, the coating liquid for the barrier layer is further coated and dried on the heat-sensitive recording layer. The support is appropriately selected from paper (neutral paper, acidic paper), plastic film, synthetic paper, nonwoven fabric, metal deposit, and the like. The coating amount of the heat-sensitive recording layer coating liquid is ² to 12 g / m ² , preferably 3 to 10 g / m ^{2 on} a dry weight basis.
m ² , the coating amount of the barrier layer coating liquid is 0.5 to
15 g / m ^2, preferably 1-8 g / m ² approximately.

The method for forming the release layer and the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include the same methods as those for forming the heat-sensitive recording layer and the barrier layer. Peeling the coating amount of the layer coating solution 0.1-5 g / m ² in solid weight, preferably 0.5 to 3 g / m ² approximately, 3 to 50 g / m ² coating amount of the adhesive layer by dry weight, Preferably it is about 5 to 30 g / m ² . The release layer and the pressure-sensitive adhesive layer are coated on the corresponding barrier layer and the entire surface of the support, but it is also possible to partially apply the pressure-sensitive adhesive layer, for example. The layer can be formed only on the portion where the pressure-sensitive adhesive layer is applied or on the entire surface. As for the method of forming the pressure-sensitive adhesive layer, a method in which the pressure-sensitive adhesive layer is directly applied to the back surface of the support or a method in which the pressure-sensitive adhesive layer is coated on a release layer and transferred to the back surface of the heat-sensitive recording medium is also possible.

Further, after each layer is coated, a smoothing treatment such as super calendering can be performed. Particularly, it is necessary to smooth the surface of the barrier layer on which the release layer is applied.
Necessary for obtaining a smooth release layer. It is desirable that the surface of the barrier layer has a Beck smoothness of 500 seconds or more. Further, if necessary, a barrier layer may be provided between the support and the pressure-sensitive adhesive layer to further enhance the storage stability and impart a strong gloss. Furthermore, an undercoat layer containing an organic or inorganic oil-absorbing pigment as a main component is provided between the support and the recording layer, a perforation is formed in the adhesive sheet, and the adhesive is printed by an edge portion or a perforation by a printing method. Various other known techniques in the field of heat-sensitive recording medium production, such as part coating except for parts, can be added as necessary.

[0030]

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 Formation of an undercoat layer 100 parts of calcined clay (trade name: Ansilex, manufactured by EMC, oil absorption 110 ml / 100 g), 1 part of a 40% aqueous solution of sodium polyacrylate, styrene having a solid concentration of 48% A coating liquid for undercoat layer obtained by mixing and stirring a composition comprising 14 parts of a butadiene copolymer latex, 50 parts of a 10% aqueous solution of polyvinyl alcohol, and 100 parts of water was mixed with 6 parts.
4 g / m ² neutral paper with 9 g / m coating amount after drying on one side
^The resultant was coated and dried so as to obtain an undercoat layer.

Preparation of Solution A 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluoran, 5% aqueous solution of methylcellulose 5
Parts and 40 parts of water were pulverized with a sand mill until the average particle size became 1.0 μm.

Preparation of Solution B 30 parts of bis (3-allyl-4-hydroxyphenyl) sulfone, 5 parts of a 5% aqueous solution of methylcellulose and 8 parts of water
The composition consisting of 0 parts was sand-milled to an average particle size of 1.0
Milled to a μm.

Solution C Preparation 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 is pulverized by a sand mill until the average particle diameter becomes 1.0 μm. did.

Formation of a heat-sensitive recording layer. Thermal recording obtained by mixing and stirring 55 parts of liquid A, 115 parts of liquid B, 80 parts of liquid C, 160 parts of a 10% aqueous solution of polyvinyl alcohol, 20 parts of a styrene-butadiene latex having a solid concentration of 50%, and 17 parts of calcium carbonate. Layer coating liquid,
The heat-sensitive recording layer was formed by coating and drying on the above-mentioned intermediate layer so that the coating amount after drying was 6 g / m ² .

Formation of Barrier Layer On the heat-sensitive recording layer, a styrene-butadiene-based copolymer latex having a Tg of −10 ° C. [trade name: L-1571,
Solid concentration 48%, manufactured by Asahi Kasei Co., Ltd.]
/ M ^2, and then subjected to a surface smoothing treatment using a super calender to form a barrier layer.

Formation of Release Layer Solvent-free UV-curable silicone [a mixed composition comprising 30 parts by weight of 1.5 mol% of a mercapto group-containing organopolysiloxane and 70 parts of 1.5 mol% of a vinyl group-containing organopolysiloxane, Shin-Etsu Chemical A coating liquid for a release layer obtained by mixing and stirring 100 parts of a curing initiator (acetophenone) and 3 parts of a curing initiator (acetophenone) was applied onto the barrier layer so that the coating amount was 1.0 g / m ^2. A release layer was formed by irradiating ultraviolet rays.

Formation of Pressure-Sensitive Adhesive Layer An acrylic resin-based pressure-sensitive adhesive emulsion is coated on the surface of the support opposite to the heat-sensitive recording layer side so that the coated amount after drying is 20 g / m ² , then dried and wound up and peeled off. An adhesive sheet for thermal recording without paper was obtained.

Example 2 In forming the barrier layer of Example 1, instead of the styrene-butadiene copolymer latex having a Tg of -10 ° C.,
Adhesion for heat-sensitive recording in the same manner as in Example 1 except that a styrene-butadiene copolymer latex having a Tg of 15 ° C (trade name: Polylac 750K-101, solid concentration 48%, manufactured by Mitsui Toatsu Chemicals, Inc.) was used. I got a sheet.

Example 3 In forming the barrier layer of Example 1, instead of the styrene-butadiene copolymer latex having a Tg of -10 ° C.,
Styrene-butadiene copolymer latex having a Tg of -30 ° C [trade name: Nipol LX209, solid concentration 4
5%, manufactured by Zeon Corporation] was used in the same manner as in Example 1 to obtain a heat-sensitive recording pressure-sensitive adhesive sheet.

Example 4 In forming the barrier layer of Example 1, instead of the styrene-butadiene copolymer latex having a Tg of -10 ° C.,
Composition comprising 105 parts of a styrene-butadiene copolymer latex (solid concentration: 48%) having a Tg of 25 ° C., 250 parts of a 20% aqueous solution of completely saponified polyvinyl alcohol (trade name: PVA110, manufactured by Kuraray Co., Ltd.), and 145 parts of water. Example 1 except that the coating liquid obtained by mixing and stirring the materials was used.
In the same manner as in the above, a heat-sensitive recording pressure-sensitive adhesive sheet was obtained.

Comparative Example 1 A heat-sensitive recording pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that no barrier layer was provided.

Comparative Example 2 In forming the barrier layer of Example 1, instead of the styrene-butadiene copolymer latex having a Tg of -10 ° C., completely saponified polyvinyl alcohol [trade name: PVA11]
0, manufactured by Kuraray Co., Ltd.] in the same manner as in Example 1 except that a 10% aqueous solution was used.

The following evaluation tests were performed on the thus obtained heat-sensitive recording pressure-sensitive adhesive sheet, and the results are shown in Table 1. [Coloring property] Each heat-sensitive recording pressure-sensitive adhesive sheet was colored at an applied energy of 0.50 mJ / dot using a thermal evaluation machine (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.), and the color density of the obtained recorded image was measured. Macbeth densitometer [Product name: RD-914 type,
Macbeth] in visual mode.

[Color-forming ability lowering test] The obtained rolls of the heat-sensitive recording pressure-sensitive adhesive sheet were allowed to stand at 50 ° C. and 95% RH for 3 days. Was measured for color density.

[Adhesion between Barrier Layer and Release Layer] The release layer surface of each of the obtained heat-sensitive recording pressure-sensitive adhesive sheets was rubbed with a fingertip, and the adhesion between the barrier layer and the release layer was visually evaluated. Evaluation criteria A: The release layer surface did not peel off and there was no fogging. ：: The peeling layer surface is not peeled, but is slightly cloudy. Δ: The surface of the release layer is not peeled, but is considerably clouded. ×: The release layer surface is peeled off.

[Plasticizer resistance] Polypropylene pipe (4
0 mmφ), a vinylidene chloride wrap film (trade name: KMA-W, manufactured by Mitsui Toatsu Chemicals Co., Ltd.) is wound three times, and the heat-sensitive recording pressure-sensitive adhesive sheet recorded in the evaluation test of the above-mentioned [coloring property] is wound thereon. After sandwiching the recording layer so that the recording layer surface was on the outside, and further winding a vinylidene chloride wrap film three times thereon and leaving it at room temperature for one day, the color density of the recording portion was measured with a Macbeth densitometer (visual mode).

[0048]

[Table 1]

[0049]

As is clear from Table 1, the pressure-sensitive adhesive sheet for heat-sensitive recording of the present invention does not decrease the coloring ability of the recording layer even under conditions of high temperature and high humidity, and can be adapted to high-speed printing. It is suitable for use in distribution management, which is excellent in suitability and requires no release paper, which is advantageous in terms of cost.

Claims (2)

[Claims] 1. A heat-sensitive recording pressure-sensitive adhesive sheet in which a heat-sensitive recording layer, a barrier layer and a release layer are sequentially provided on one side of a support and a pressure-sensitive adhesive layer is provided on the back side. A pressure-sensitive adhesive sheet for thermal recording, characterized by containing a butadiene copolymer. 2. The heat-sensitive recording pressure-sensitive adhesive sheet according to claim 1, wherein the glass transition point (Tg) of the emulsion-polymerized styrene-butadiene copolymer is -20 to 20 ° C.