JP2002275437A - Adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive sheet causing neither foaming nor repelling when applying an adhesive, good at adhesion to a polyolefin wrap, and when used as a thermal printing element, causing neither printing sensitivity decline nor print void. SOLUTION: This adhesive sheet is obtained by laminating a substrate with an adhesive layer, a silicone-based releasant layer and a release base paper in this order, and simultaneously meets the requirements(1) and (2) described below: (1) the adhesive forming the adhesive layer is an acrylic emulsion adhesive comprising 100 pts.wt. of a base polymer and 2-20 pts.wt. of a rosin-based tackifier >=80 deg.C in softening point; wherein the base polymer is a homopolymer and/or copolymer obtained by emulsion polymerization of a (meth)acrylic ester monomer or its mixture with another copolymerizable monomer in the presence of a surfactant consisting mainly of a polyoxyethylene alkyl ether- and/or polyoxyethylene alkyl ester-based compound, and (2) the release base paper is glassine-type paper or clay coated-type paper provided with a coating layer consisting mainly of a pigment and a binder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive sheet, and more particularly to a heat-sensitive recording material which does not generate foaming or cissing when a pressure-sensitive adhesive is applied and has good adhesion to a polyolefin wrap. The present invention relates to a pressure-sensitive adhesive sheet having no reduction in recording sensitivity and no white spots on printing.

[0002]

2. Description of the Related Art Adhesive sheets have been used for labels, seals, stickers, patches and the like in a very wide range such as commercial, office and home use. The general configuration of the pressure-sensitive adhesive sheet is formed by laminating a surface substrate, a pressure-sensitive adhesive, and a release paper. Paper, film, metal foil, etc. are used as the surface substrate, and the release paper is coated with a release agent such as a silicone compound or a fluorine compound on high density base paper such as glassine paper, clay coated paper, polyethylene laminated paper, etc. The engineered one is used. As the pressure-sensitive adhesive, rubber-type, acrylic-type, vinyl ether-type, etc. emulsion-type, solvent-type, hot-melt-type pressure-sensitive adhesives and the like are used. Among them, acrylic emulsion adhesive is safe,
Widely used in terms of quality and cost.

[0003] As a method for producing a pressure-sensitive adhesive sheet obtained by applying a pressure-sensitive adhesive layer to the surface of a release paper using such a pressure-sensitive adhesive and laminating a surface substrate, a reverse roll coater, a comma coater, A coating method using an air knife coater, a knife coater or the like has been adopted. Regardless of which coater is used, a transfer method in which a pressure-sensitive adhesive is applied onto release paper and then a surface substrate is attached is predominant.

A polyoxyethylene alkylphenyl ether-based surfactant, which is a typical emulsifier used when emulsion-copolymerizing an acrylic emulsion pressure-sensitive adhesive, has excellent emulsifying power and wettability with a release paper (silicone-based release agent). Has been widely used because of its superiority. However, because of its excellent wettability, there is a problem that bubbles are generated during stirring and coating as a reverse phenomenon. Therefore, there has been a problem that a coating surface defect due to bubbles may occur during coating.

On the other hand, POS (point-to-
f sales) With the expansion of systemization, the use of adhesive paper as a label is increasing. In many supermarkets, convenience stores, and the like, a label on which a product name, contents, and the like are printed is affixed to a tray, and food and the like are put into a wrap. With the recent increase in environmental protection and the need to reduce polyvinyl chloride due to the dioxin problem and the like, switching to so-called polyolefin wrap such as polyethylene or polypropylene instead of polyvinyl chloride has been progressing. Further, a polyoxyethylene alkylphenyl ether-based surfactant used in the production of the pressure-sensitive adhesive composition,
It has been pointed out that the chemical may be harmful to human health, the environment, and ecosystems, and there is a demand for a clear harmless surfactant.

[0006] Polyolefin wrap does not generate dioxin during incineration, and can be considered for environmental issues. However, the acrylic emulsion pressure-sensitive adhesive emulsion-copolymerized using a conventional polyoxyethylene alkylphenyl ether-based surfactant easily adheres to polar polyvinyl chloride, and there was no particular problem. It does not easily adhere to polyolefin wraps, and is also affected by the effect of antifog agents such as polyhydric alcohol fatty acid esters that are kneaded into the wrap to impart antifogging properties and self-adhesion. There was a problem in using the pressure-sensitive adhesive used for the vinyl substrate as it is for the polyolefin wrap.

Further, a heat-sensitive recording sheet is preferably used which utilizes a color reaction between a colorless or light-colored basic dye and an organic or inorganic colorant to bring both color-forming substances into contact with heat to obtain a recorded image. Are known. Such thermosensitive recording sheets are relatively inexpensive, and the recording equipment is compact and easy to maintain, so that they are used not only as recording media for facsimile machines and various calculators but also in a wide range of fields.
For example, as one of the application fields, POS of retail stores, etc.
(Point of Sales) With the expansion of systematization, cases used as labels are increasing.

In general, a heat-sensitive recording label is manufactured by applying a pressure-sensitive adhesive on a release paper and then laminating a heat-sensitive recording material. Usually, rubber-based, acrylic-based, and the like are used as the pressure-sensitive adhesive in the pressure-sensitive adhesive layer, and an acrylic emulsion type is particularly often used. Therefore, even during storage for a long time before being used as a label, low molecular weight components such as surfactants contained in the pressure-sensitive adhesive layer migrate to the heat-sensitive recording layer, causing a decrease in recording sensitivity and printing. There is a problem that white spots and the like occur.

For this reason, a thermosensitive recording medium provided with a back coat layer mainly composed of a water-soluble polymer has been proposed, but the water-soluble polymer permeates into the support to obtain a sufficient barrier property. However, the storage stability of the recorded image was poor. In addition, there were problems such as a decrease in whiteness of the recording layer during application and drying of the back coat layer, and an increase in cost due to an increase in the number of manufacturing steps.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure-sensitive adhesive sheet comprising a surface substrate, a pressure-sensitive adhesive layer, a silicone-based release agent layer, and a release base paper laminated thereon. An object of the present invention is to obtain a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having good adhesion to a polyolefin wrap without repelling. Further, an object of the present invention is to provide a pressure-sensitive adhesive sheet which can be used for a heat-sensitive recording label to produce a heat-sensitive recording label excellent in stability of a recorded image with no decrease in recording sensitivity and no white spots in printing. It is in.

[0011]

The present invention includes the following inventions. (1) In a pressure-sensitive adhesive sheet formed by laminating a surface base material, a pressure-sensitive adhesive layer, a silicone-based release agent layer, and a release base paper in this order, the pressure-sensitive adhesive layer and the release base paper simultaneously satisfy the following conditions (a) and (b). An adhesive sheet characterized by filling. (A) The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is formed by mixing a (meth) acrylate monomer or a mixture of a (meth) acrylate monomer and another copolymerizable monomer with a polyoxyethylene alkyl ether-based and / or polyoxyethylene A homopolymer and / or copolymer obtained by emulsion polymerization using a surfactant containing an ethylene alkyl ester as a main component is contained as a base polymer, and a softening point is 80 ° C. or higher with respect to 100 parts by weight of the base polymer. 2 to 20 parts by weight, preferably 3
It is an acrylic emulsion pressure-sensitive adhesive containing up to 15 parts by weight, more preferably 4 to 10 parts by weight. (B) The release base paper is glassine type paper or a clay coated type paper provided with a coating layer containing a pigment and a binder as main components.

(2) The pressure-sensitive adhesive sheet according to (1), wherein the surface substrate is a thermosensitive recording medium having a thermosensitive recording layer. (3) When the colorant in the heat-sensitive recording layer is 4,4'-bis (N-
p-Trisulfonylurea) diphenylmethane, Np
-Tolylsulfonyl-N'-phenylurea, 4-hydroxy-4'-isopropoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone,
The pressure-sensitive adhesive sheet according to item (1) or (2), which is at least one colorant selected from 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether.

Further, the present invention further includes the following inventions. (4) The (meth) acrylate monomer of the base polymer includes methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and isobutyl (meth) acrylate. , T-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate (1) is at least one type of monomer
The pressure-sensitive adhesive sheet according to any one of the above items (3).

(5) Other copolymerizable monomers of the base polymer include vinyl acetate, styrene, ethylene, vinyl chloride, vinylidene chloride, ethylenically unsaturated carboxylic acid,
The crosslinkable monomer, (α-methyl) styrene, N-alkyl (meth) acrylamide, and at least one monomer selected from (meth) acrylonitrile according to any one of the above items (1) to (4). Adhesive sheet.

(6) The polyoxyethylene alkyl ether surfactant is selected from polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene higher alcohol ether. (1) which is at least one of
The pressure-sensitive adhesive sheet according to any one of the above items (5).

(7) The polyoxyethylene alkyl ester surfactant is at least one selected from polyoxyethylene oleate, polyoxyethylene laurate, polyoxyethylene palmitate, and polyoxyethylene stearate ( The pressure-sensitive adhesive sheet according to any one of items 1) to 6).

(8) The rosin tackifier comprises:
At least one rosin resin selected from rosin, polymerized rosin, hydrogenated rosin, rosin ester and hydrogenated rosin ester having a softening point of 80 ° C. or higher (1) to (1).
(7) The adhesive sheet according to any one of the above (7).

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An acrylic emulsion pressure-sensitive adhesive emulsion-copolymerized using a polyoxyethylene alkylphenyl ether-based surfactant, which has been frequently used in various recording pressure-sensitive adhesive sheets, has an emulsifying power, a silicone-based pressure-sensitive adhesive. The wettability to the release agent was excellent. However, since the surfactant activity of the polyoxyethylene alkyl phenyl ether-based surfactant remaining in the acrylic emulsion adhesive is too strong, foaming occurs when the adhesive is stirred or when applied on a silicone-based release agent. There is a problem that the agent-coated surface becomes defective. Further, an acrylic emulsion pressure-sensitive adhesive emulsion-copolymerized by using a polyoxyethylene alkylphenyl ether-based surfactant, which has been widely used, has a problem that its adhesiveness to a polyolefin film is inferior. Further, it has been pointed out that alkylphenyl or alkylphenol compounds may be harmful.

The present inventors emulsify (co) using a surfactant containing a polyoxyethylene alkyl ether and / or a polyoxyethylene alkyl ester as a main component, which is not a phenyl compound, as a surfactant. This problem was solved by finding that the use of a polymerized acrylic emulsion pressure-sensitive adhesive significantly improved the adhesion to a polyolefin film.

The pressure-sensitive adhesive used in the present invention is a polymer obtained by emulsion polymerization of at least one ester group-containing monomer selected from the group of (meth) acrylates using the above-mentioned surfactant. As a base polymer. As the base polymer, -73 ° C to -4
Polymers having a glass transition temperature (Tg) of 3 ° C. are desirable. If the Tg is less than -73 ° C, the cohesive strength is significantly reduced, and if it exceeds -43 ° C, the adhesiveness to the adherend at a low temperature tends to be reduced. The polymer is preferably produced by a known emulsion copolymerization method (for example, a primary charge polymerization method, a monomer addition polymerization method, a pre-emulsion addition polymerization method, etc.). As the base polymer, (meth)
Copolymers comprising at least one ester group-containing monomer selected from the group of acrylic esters and at least one copolymerizable monomer are preferred.

Examples of the ester group-containing monomers selected from the group of (meth) acrylates for producing base polymers include, for example, methyl (meth) acrylate and (meth) acrylate.
Ethyl acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylic acid-2- Examples include ethylhexyl, isononyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate.

Examples of the copolymerizable monomer include vinyl acetate, styrene, ethylene, vinyl chloride, vinylidene chloride, ethylenically unsaturated carboxylic acid, crosslinkable monomer,
(Α-methyl) styrene, N-alkyl (meth) acrylamide, (meth) acrylonitrile and the like.

Examples of the ethylenically unsaturated carboxylic acid copolymerized with (meth) acrylic esters include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, and alkyl groups having carbon atoms of 1 to 1
2, monoethyl maleate, hydroxyethyl (propyl) mono maleate, phthalic acid, monoalkyl esters of itaconic acid, and the like.

Examples of the crosslinkable monomer copolymerized with (meth) acrylates include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and (meth) acrylic acid. Acid-3-
Hydroxyl-containing monomers such as mono (meth) acrylate of hydroxyethyl, polyethylene glycol or polypropylene glycol, epoxy-containing monomers such as glycidyl (meth) acrylate, divinylbenzene, divinylsilane, diallyl phthalate, cyclopentadiene, methylenebisacrylamide, diallyl Monomers having two or more unsaturated bonds, such as maleate and tetraallyloxyethane, can be mentioned.

In the present invention, the polyoxyethylene alkyl ether-based surfactant used in the production of the pressure-sensitive adhesive includes polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether. And polyoxy higher alcohol ethers. Examples of the polyoxyethylene alkyl ester surfactant include polyoxyethylene oleate, polyoxyethylene laurate, polyoxyethylene palmitate, and polyoxyethylene stearate.

As the surfactant which can be used in combination with the surfactant of the present invention, anionic alkyl sulfate ester-based surfactants;
Specific examples include sodium lauryl sulfate, higher alcohol sodium sulfate, triethanolamine lauryl sulfate, and polyoxyethylene sodium lauryl sulfate.

The pressure-sensitive adhesive of the present invention contains a tackifier in order to improve the adhesion to the polyolefin wrap. Examples of the tackifier include rosin resin, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, hydrogenated petroleum resin, styrene resin, and alkylphenol resin. Is the best. The rosin tackifier of the present invention is a rosin resin having a softening point of 80 ° C. or higher, and includes rosin, polymerized rosin, hydrogenated rosin, rosin ester, and hydrogenated rosin ester.

The rosin-based tackifier has a smaller molecular weight than a (meth) acrylate polymer as a base polymer, and is approximately several hundred to several thousand oligomers. For this reason, when it is contained in the pressure-sensitive adhesive, it is migrated to the surface substrate when stored for a long time, and bleeding (transparency) of the surface substrate is likely to occur. When the softening point is low, the composition becomes more liquid at room temperature, and this tendency is remarkable. Further, when the surface substrate is a heat-sensitive recording medium, the colorant is affected, resulting in a decrease in sensitivity and white spots in printing. However, if the rosin-based tackifier has a softening point of 80 ° C. or higher, it is solid at normal temperature and migration to the surface substrate is small.

The rosin tackifier is used in an amount of 2 to 20 parts by weight, preferably 3 to 15 parts by weight, more preferably 4 parts by weight, based on 100 parts by weight of the base polymer mainly composed of a (meth) acrylate polymer. To 10 parts by weight. If the amount is less than 2 parts by weight, the adhesion to the polyolefin wrap will be insufficient, and if it exceeds 20 parts by weight, the tackiness will be lost, the migration to the surface substrate will be remarkable, and the surface substrate will bleed (clear). As long as the effects of the present invention are not impaired, a thickener, a wetting agent, a leveling agent, an antifoaming agent, and the like may be appropriately added to the pressure-sensitive adhesive as needed.

Although the procedure for applying the pressure-sensitive adhesive is not limited, it is usually applied on a silicone-based release agent layer of a release base paper having a silicone-based release agent applied to the surface. As a method of applying the pressure-sensitive adhesive, for example, a roll coater, a knife coater, a bar coater, a slot die coater, or the like is used, and the amount of application is adjusted in a range of about 5 to 50 g / m ² in terms of dry weight.

The release base paper to be coated with the pressure-sensitive adhesive of the present invention requires glassine type paper or clay coat type paper containing pigment and binder as main components. As the release base paper, a polyethylene laminate type, a film or the like may be used. These release base papers have considerably high surface smoothness and maintain the same smoothness even after coating with a silicone release agent.However, in the case of the pressure-sensitive adhesive of the present invention, polyoxyethylene alkyl is used to suppress foaming. Since it is manufactured using a surfactant containing ether-based and / or polyoxyethylene alkyl ester-based components as a main component, the wettability is somewhat insufficient. Therefore, in the case of a release base paper such as a polyethylene laminate type or a film, cissing occurs at the time of applying the pressure-sensitive adhesive of the present invention, which is a problem at the time of application.

However, when the release base paper is glassine type paper or clay coated type paper, the smoothness of the surface is reduced, the smoothness is not high even after the silicone release agent is applied, and the wettability of the release agent coated surface is low. Will be enough. Therefore, repelling does not occur even when the pressure-sensitive adhesive of the present invention is applied, and a good coated surface can be obtained. Therefore, the release base paper in the pressure-sensitive adhesive sheet of the present invention is a clay-coated paper mainly composed of glassine-type paper and a pigment and a binder.

As the clay coat type paper, base paper such as kraft paper or woodfree paper is used. Examples of the pigment include inorganic pigments such as kaolin, clay, calcium carbonate, calcined clay, calcined kaolin, titanium oxide, and silica, and organic pigments such as plastic pigment. Of course, two or more kinds can be used in combination. Examples of the binder include casein, dextrin, starch, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, styrene-butadiene copolymer, ethylene-vinyl chloride copolymer, methyl methacrylate-butadiene copolymer, and ethylene-acetic acid. A natural or synthetic resin of a vinyl copolymer or a (meth) acrylate copolymer may be used, and two or more kinds may be used in combination.

The ratio of the pigment to the binder is preferably 30 to 200 parts by weight based on 100 parts by weight of the pigment. When the amount is less than 30 parts by weight, the barrier property at the time of applying the solvent-type silicone-based release agent is insufficient, and when the amount is more than 200 parts by weight, blocking by winding occurs. Coating amount is 2
Preferably to 20 g / m ^2, when less than 2 g / m ^2, without the desired release force barrier properties is insufficient is obtained, 20 g / m
^If it exceeds ² , the effect is saturated.

As long as the effects of the present invention are not impaired, various auxiliaries such as a wetting agent, an antifoaming agent and a lubricant can be added. The apparatus for applying the coating liquid is not particularly limited. For example, a bar coater, a direct gravure coater, a gate roll coater, a blade coater, an air knife coater, or the like is appropriately used.

As the silicone release agent applied to the release base paper, a solvent type or a non-solvent type is used, and the dry weight is 0.1%.
After coating so as to have a thickness of about 05 to 3 g / m ² , a release agent layer is formed by heat curing, electron beam or ultraviolet curing, or the like. The apparatus for applying the silicone release agent to the release base paper is not particularly limited, but for example, a bar coater, a direct gravure coater, an offset gravure coater, an air knife coater, a multi-stage roll coater, or the like is appropriately used.

Examples of the surface substrate of the present invention include cast coated paper, art paper, coated paper, woodfree paper, heat-sensitive paper, synthetic paper, vapor-deposited paper, cloth, nonwoven fabric, metal foil, and various polymer films. Is appropriately selected according to the purpose and purpose. In the case of a paper substrate, any of so-called neutral papers containing an acidic filler or an alkaline filler such as calcium carbonate as a main component and having a pH of about 6 to a slightly acidic to about 9 to a weakly alkaline may be used. As the surface substrate of the present invention, a surface substrate (recorded body) in which a recording layer is further provided on the above-mentioned surface substrate can be used. Electrophotographic recording,
Recording layers suitable for recording systems such as ink jet recording, melt thermal transfer recording, sublimation thermal transfer recording, and thermal recording can be given. Above all, the thermal recording medium is preferable because the apparatus is compact and economically advantageous.

The present inventors have also conducted intensive studies on the case of using a heat-sensitive recording medium as a surface substrate of an adhesive paper. As a result, polyoxyethylene alkyl phenyl ether surfactants, which are typical emulsifiers of acrylic emulsion adhesives, have a low molecular weight and are easily migrated to the heat-sensitive recording layer. Because of this, it was found that the ink was easily compatible with the color former, and that the sensitivity was reduced and white spots were generated. Therefore, when an acrylic emulsion pressure-sensitive adhesive emulsion-polymerized using a surfactant containing a polyoxyethylene alkyl ether type and / or a polyoxyethylene alkyl ester type as a main component is used, problems such as a decrease in recording sensitivity and white spots are caused. Had a remarkable effect on the solution.

Further, the colorant in the heat-sensitive recording layer is selected from 4,4'-bis (Np-trisulfonylurea) diphenylmethane and Np-tolylsulfonyl-N'-phenylurea which are resistant to low molecular weight components. , 4-hydroxy-
4'-isopropoxydiphenyl sulfone, bis (3-
Allyl-4-hydroxyphenyl) sulfone, 2,2 '
-Bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether
It was found that the use of such a coloring agent had a further effect, and the problems such as a decrease in the recording sensitivity of the thermosensitive recording medium and white spots were solved.

As the base paper of the heat-sensitive recording material, wood pulp such as softwood and hardwood, non-wood pulp such as kenaf, bamboo and hemp, synthetic pulp such as polyester and polyolefin, or synthetic fiber, furthermore, glass fiber and ceramic fiber And the like obtained by using inorganic fibers and the like as raw materials.
Wood pulp and non-wood pulp include ECF pulp, T
CF pulp and the like can also be used.

In the stock, for example, talc, kaolin, clay, calcined kaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide,
Zinc hydroxide, magnesium sulfate, calcium silicate, white carbon, aluminosilicate, silica, sericite,
Bentonite, smectite, polystyrene resin microparticles, urea formalin resin microparticles, fine hollow microparticles, and other publicly known fillers and organic synthetic fillers, and various yields conventionally used within a range that does not impair the desired effects of the present invention. An improver and a drainage improver are used.

For example, polyvalent metal compounds such as Al, Fe, Sn, and Zn (e.g., easily dispersed in water such as basic aluminum such as a sulfate band, aluminum chloride, sodium aluminate, basic aluminum chloride, and basic polyaluminum hydroxide) and water. Water-soluble aluminum compounds such as alumina sol, or ferrous sulfate, ferric chloride, etc.) and various sizing agents (alkyl ketene dimer, alkenyl succinic anhydride, styrene-acrylic, higher fatty acid, petroleum resin) Sizing agents and rosin-based sizing agents) and various starches, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide / polyamine resin, polyethyleneimine, polyamine, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide , Hydrophilic crosslinked polymer particles dispersed And their derivatives, or colloidal silica, a variety of compounds, such as bentonite can be exemplified. In addition, an internal additive for papermaking such as a dye, a fluorescent brightener, a pH adjuster, an antifoaming agent, a pitch control agent, and a slime control agent can be appropriately added as needed.

The papermaking method is also not particularly limited. For example, acidic papermaking having a papermaking pH of about 4.5, an alkaline filler such as calcium carbonate as a main component, and a papermaking pH of about 6 to about 9 to about 9 are used. It can be applied to all papermaking methods such as the so-called neutral papermaking method to make it weakly alkaline,
As the paper machine, a fourdrinier paper machine, a twin wire paper machine, a round mesh paper machine, a Yankee paper machine, or the like can be appropriately applied.

On the other hand, as the basic dye contained in the heat-sensitive recording layer in the present invention, various known dyes can be mentioned, for example, the following ones. 3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3-
(4-diethylamino-2-methylphenyl) -3-
A blue-coloring dye such as (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylamino-benzo [a] fluoran, 3- (N
Green-forming dyes such as -ethyl-N-p-tolyl) amino-7-N-methylanilinofluoran, 3-diethylamino-7-anilinofluoran and 3-diethylamino-7-dibenzylaminofluoran.

3,6-bis (diethylamino) fluoran-γ-anilinolactam, 3-cyclohexylamino-6-chlorofluoran, 3-dibutylamino-6-methyl-7-bromofluoran, 3-diethylamino-7
-Methylfluoran, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, rhodamine (o-chloroanilino) lactam, rhodamine (p-chloroanilino) lactam,
3-diethylamino-7,8-benzofluoran, 3-
(N-ethyl-p-toluidino) -7-methylfluoran, 3-diethylamino-6,8-dimethylfluoran, 3- (N-ethyl-N-isoamyl) amino-benzo [a] fluoran, 3,3 '-Bis (1-n-butyl-2-methylindol-3-yl) phthalide, 2-
Red coloring dyes such as (4-dodecyloxy-3-methoxystyryl) quinoline;

3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 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-chlorophenylamino) fluoran, 3-di (n-butyl) amino-7- (o-chlorophenylamino) fluoran, 3-
Diethylamino-7- (o-fluorophenylamino)
Fluoran, 3-di (n-butyl) amino-7- (o-
Fluorophenylamino) fluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p- Toluzino) Fluoran, 3- (N-
Ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-
6-chloro-7-anilinofluoran, 3- (N-methyl-Nn-propylamino) -6-methyl-7-anilinofluoran, 3-dimethylamino-6-methyl-7
-Anilinofluoran, 3-dibutylamino-6-methyl-7-m-toluidinofluoran, 3- (Nn-hexyl-N-ethyl) amino-6-methyl-7-anilinofluoran , 3- (N-ethyl-N-isobutyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-p-ethoxyanilinofluoran, 3-pyrrolidino-6-methyl -7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro [Phthalide-3,9'-xanthen-2'-ylamino] phenyl} propane, 3-diethylamino-7-
Black coloring dyes such as (3'-trifluoromethylphenyl) aminofluorane;

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, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-
2-yl] -4,5,6,7-tetrabromophthalide,
3-p- (p-dimethylaminoanilino) anilino-6
-Methyl-7-chlorofluorane, 3-p- (p-chloroanilino) anilino-6-methyl-7-chlorofluoran, 3,6-bis (dimethylamino) fluorene-9
Dyes having an absorption wavelength in the near infrared region, such as -spiro-3 '-(6'-dimethylamino) phthalide. Of course,
It is not limited to these, and two or more of them can be used in combination as needed.

As the colorant, a known colorant can be used. From the viewpoint of recording sensitivity and white spots, 4,4'-
Bis (Np-tolylsulfonylurea) diphenylmethane, Np-tolylsulfonyl-N'-phenylurea, 4-hydroxy-4'-isopropoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, At least one colorant selected from 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether is preferred. The use ratio of the basic dye and the colorant is appropriately selected according to the type of the basic dye and the colorant to be used, and is not particularly limited, but is generally 1 part by weight of the basic dye. The color former is used in an amount of 1 to 50 parts by weight, preferably 2 to 10 parts by weight.

The coating material for the heat-sensitive recording layer containing these substances is
Generally, water is used as a dispersion medium, and ball mills, attritors,
It is prepared by dispersing the dye and the color former together or separately using a stirring / pulverizer such as a sand mill.

In the coating solution, 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, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, urea resin, At least one of a melamine resin, an amide resin, a polyurethane resin and the like is blended in an amount of about 5 to 30% by weight based on the total solid content of the recording layer.

Various auxiliaries can be added to the coating solution, if necessary. For example, dispersants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate and fatty acid metal salts. And waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax and ester wax, antifoaming agents, coloring dyes and the like are appropriately added.

It is also possible to use various pigments together in the coating liquid, for example, kaolin, clay, calcium carbonate, calcined clay, calcined kaolin, titanium oxide, diatomaceous earth,
Examples include inorganic pigments such as finely divided anhydrous silica and activated clay, and organic pigments such as styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and raw starch particles.

Further, a sensitizer can be used in combination depending on the purpose. Specific examples of the sensitizer include, for example, stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebisstearic acid amide, behenic acid amide, methylenebisstearic acid amide , N-
Methylol stearamide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate,
Benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, 2-naphthyl benzyl ether, m-terphenyl, dibenzyl oxalate, di-p-methylbenzyl oxalate, di-p-oxalate Chlorobenzyl, 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-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (3
-Methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetotoluizide, p-acetophenethidide,
Examples thereof include N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane and the like.

In the present invention, it is possible to add a storability improving agent to the heat-sensitive recording layer. Examples of such a preservability improver include the following. 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,
2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,2′-ethylidenebis (4,6-di-
tert-butylphenol), 4,4′-thiobis (2-
Methyl-6-tert-butylphenol), 4,4′-butylidenebis (6-tert-butyl-m-cresol),
1- [α-methyl-α- (4′-hydroxyphenyl)
Ethyl] -4- [α ′, α′-bis (4 ″ -hydroxyphenyl) ethyl] benzene, 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), 4,4'-
Dihydroxy-3,3 ', 5,5'-tetrabromodiphenylsulfone, 4,4'-dihydroxy-3,3',
5,5′-tetramethyldiphenyl sulfone, 2,2-
Bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) Hindered phenol compounds such as propane, 1,4-diglycidyloxybenzene, 4,4′-diglycidyloxydiphenylsulfone, 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenylsulfone, diglycidyl terephthalate, Epoxy compounds such as cresol novolak type epoxy resin, phenol novolak type epoxy resin, bisphenol A type epoxy resin, N, N'-di-2-naphthyl-p-phenylenediamine, 2,2'-methylenebis (4,6-diene -Tert-butylphenyl) phosphate sodium or polyvalent Salt, bis (4-ethylene iminocarbonyl aminophenyl) include methane and the like.
The amounts of these sensitizers and storability improvers are not particularly limited, but generally it is desirable to adjust them in the range of about 4 parts by weight or less based on 1 part by weight of the color former.

It is preferable to provide a protective layer on the heat-sensitive recording sheet, because the storage stability of the recording is further improved. For the protective layer formed on the heat-sensitive recording layer, a water-soluble polymer or a water-dispersible resin having a film-forming property is used. Specific examples of such water-soluble polymers or water-dispersible resins include, for example, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, fully saponified polyvinyl alcohol,
Partially saponified 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, styrene / acrylic acid copolymer Water-soluble polymers such as coalescing salts, ethylene / acrylic acid copolymer salts, urea resins, melamine resins, amide resins, and styrene / butadiene copolymer latex, acrylic resin latex, polyester polyurethane ionomer,
Water-dispersible resins such as polyether polyurethane ionomers and the like can be mentioned.

It is also possible to add a pigment to the protective layer, for example, kaolin, clay, calcium carbonate, calcined clay, calcined kaolin, titanium oxide, diatomaceous earth,
Urea / formalin resin filler and the like can be mentioned. The amount used is 30 to 80% by weight, preferably 40 to 70% by weight, more preferably 45 to 65% by weight based on the protective layer.

Further, various auxiliaries can be added to the protective layer, if necessary. For example, dispersants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate and fatty acid metal salts. Lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax,
An antifoaming agent, a coloring dye and the like are appropriately added. In particular, the combined use of a lubricant and a waterproofing agent in the protective layer further improves the blocking resistance.

The method for forming the heat-sensitive recording layer and the protective layer is not particularly limited.
After coating and drying the coating solution for the recording layer on the support by a suitable coating method such as buriba blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, die coating, gravure coating, etc., further protection It is formed by a method such as applying and drying a layer coating liquid on the recording layer.

[0059]

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 thereto. In the examples, parts and% indicate "parts by weight" and "% by weight" unless otherwise specified.

Example 1 "Production of adhesive" 2-ethylhexyl acrylate 93
Part, vinyl acetate 6.5 parts and acrylic acid 0.5 part as a surfactant, polyoxyethylene lauryl ether (trade name: Emulgen 105 / Kao Corporation)
1.0 part and 30 parts of ion-exchanged water were added to an emulsifier aqueous solution and stirred to form a pre-emulsion. In a reaction vessel equipped with a stirrer, thermometer, and cooling tube, 1.0 part of polyoxyethylene lauryl ether (trade name: Emulgen 105 / Kao Corporation), 0.3 parts of sodium acetate, 0.8 parts of sodium persulfate , 30 parts of ion-exchanged water, an aqueous solution of an emulsifier was charged, the temperature of the solution was increased to 75 ° C. while stirring and passing nitrogen gas, 5/100 of the pre-emulsion was added, initial polymerization was performed for 30 minutes, and the remaining Was added dropwise over 4 hours, and polymerization was carried out while maintaining the temperature at 75 to 80 ° C.
After the completion of the dropwise addition, the mixture was kept at 80 ° C. to carry out late-stage polymerization to obtain a copolymer emulsion. After neutralizing this copolymer emulsion with aqueous ammonia (concentration 25%),
A viscosity was adjusted to 5000 mpas by adding a thickener to obtain a base polymer. To 100 parts of the obtained base polymer, 10 parts of an emulsion-type rosin-based tackifier having a softening point of 160 ° C (trade name: Superester E-650 / Arakawa Chemical Co., Ltd.) was blended to obtain a pressure-sensitive adhesive.

"Manufacture of release paper" 83 g / m2^TwoGrass
Thermosetting solvent silicone (trade name: SRX3)
45 / Dow Corning Toray) with a bar coater
1.0g / m dry weight ^TwoAnd release paper.
Obtained.

"Production of pressure-sensitive adhesive sheet"
30 g / dry weight of the above-mentioned pressure-sensitive adhesive
m ^TwoApply with a reverse roll coater so that
An adhesive layer was formed. Next, a surface group is placed on the surface of this adhesive layer.
Cast paper (trade name: N Mirror 73 / Oji Paper)
(Manufactured by the company).

Example 2 In the production of the pressure-sensitive adhesive of Example 1, polyoxyethylene lauryl ether (trade name: Emulgen 105 / manufactured by Kao Corporation) was used as a surfactant when polymerizing the pressure-sensitive adhesive, and polyoxyethylene oleate was used. (Product name: New Call 170
/ Manufactured by Nippon Emulsifier Co.) to obtain a pressure-sensitive adhesive sheet in the same manner as in Example 1.

Example 3 In the production of the pressure-sensitive adhesive of Example 1, 1.0 part of polyoxyethylene lauryl ether (trade name: Emulgen 105 / manufactured by Kao Corporation) was used as a surfactant when polymerizing the pressure-sensitive adhesive. Example 1 was changed except that 0.5 parts of ethylene oleyl ether (trade name: Emulgen 404 / Kao Corporation) and 0.5 parts of polyoxyethylene oleate (trade name: Newcol 170 / Nippon Emulsifier) were used. In the same manner as in the above, an adhesive sheet was obtained.

Example 4 In the production of the pressure-sensitive adhesive of Example 1, a rosin-based tackifier having a softening point of 160 ° C. (trade name: Superester E)
-650 / Arakawa Chemical Co., Ltd.) and a rosin-based tackifier having a softening point of 100 ° C. (trade name: Superester E-7)
20 / Arakawa Chemical Co., Ltd.) to obtain an adhesive sheet in the same manner as in Example 1.

Example 5 An adhesive sheet was obtained in the same manner as in Example 1 except that in the production of the release paper of Example 1, the glassine paper having a basis weight of 83 g / m ² was changed to a clay coat type release base paper. .
Clay coat type release base paper is kaolin (trade name: UW-90 / manufactured by EMC) 1 on high quality paper of 80 g / m ²
00 parts, acrylic resin (trade name: Ricabond ET-84)
/ Chuo Rika Co., Ltd.) 100 parts, lubricant (trade name: NOPCO C)
-104 / manufactured by San Nopco Co., Ltd .; 1.0 g of an antifoaming agent (trade name: Nopco 1407K / manufactured by San Nopco Co.) was applied and dried at 10 g / m ^2, and subjected to a super calendar treatment. Manufactured.

Example 6 Cast paper (N-mirror 73 /
Pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that Oji Paper Co., Ltd.) was changed to the following thermosensitive recording medium.

"Manufacture of thermosensitive recording medium" Manufacture of support for surface base material 25 parts of NBKP (550 ml of CSF), LBKP (CS
F 560 ml) to a pulp slurry containing 75 parts
Kaolin was added so that the paper ash content was 5.0%, and as a sizing agent, a rosin size of 1.5% based on the absolutely dried pulp and a sulfate band of 2.0% were added. This pulp slurry is paper-made by a fourdrinier multi-cylinder cylinder dryer paper machine, processed by a four-stage super calender, and processed into 58 g of rice tsubo /
to obtain a support surface substrate of m ^2.

Preparation of Solution A A composition comprising 10 parts of 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-phenylaminofluoran, 5 parts of a 5% aqueous solution of methylcellulose, and 40 parts of water was subjected to sand milling. It was pulverized until the average particle size became 3 μm. Solution B Preparation 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 3 µm.
m.

Preparation of Solution C 20 parts of 1,2-di (3-methylphenoxy) ethane, 5 parts
A composition comprising 5 parts of an aqueous methylcellulose solution and 55 parts of water was pulverized by a sand mill until the average particle diameter became 3 μm. Liquid D preparation 10% acetoacetyl group-modified polyvinyl alcohol aqueous solution 200 parts, kaolin (trade name: UW-90, manufactured by EMC) 100 parts, 30% zinc stearate dispersion liquid 30 parts,
And a composition comprising 100 parts of water were mixed and stirred to obtain a coating liquid.

[Formation of Thermosensitive Recording Layer] 55 parts of A solution and 115 parts of B solution were applied on the surface of the support obtained by manufacturing the support of the surface substrate.
Part, liquid C 80 parts, 10% polyvinyl alcohol aqueous solution 8
A coating liquid obtained by mixing and stirring 0 parts and 35 parts of calcium carbonate was applied and dried so that the coating amount after drying was 6 g / m ² , to obtain a recording layer. After applying and drying the liquid D on the recording layer so that the coating amount after drying was 5 g / m ² , a calender treatment was performed to obtain a heat-sensitive recording material (surface substrate).

Example 7 In the preparation of the thermosensitive recording medium of Example 6, 4-hydroxy-4'-isopropoxydiphenyl sulfone was replaced with 4,4'-bis (Np-trisulfonylurea) diphenylmethane Except having changed to, it carried out similarly to Example 6, and obtained the adhesive sheet.

Comparative Example 1 In the production of the pressure-sensitive adhesive of Example 1, polyoxyethylene lauryl ether (trade name: Emulgen 105 / manufactured by Kao Corporation) was used as a surfactant when polymerizing the pressure-sensitive adhesive, and polyoxyethylene nonylphenyl was used. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that ether (trade name: Emulgen 903 / manufactured by Kao Corporation) was used.

Comparative Example 2 In the production of the pressure-sensitive adhesive of Example 1, polyoxyethylene lauryl ether (trade name: Emulgen 105 / manufactured by Kao Corporation) was used as a surfactant when polymerizing the pressure-sensitive adhesive, and polyoxyethylene octylphenyl was used. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that ether (trade name: Emulgen 810 / manufactured by Kao Corporation) was used.

Comparative Example 3 In the production of the pressure-sensitive adhesive of Example 1, a rosin-based tackifier having a softening point of 160 ° C. (trade name: Superester E)
-650 / Arakawa Chemical Co., Ltd.) and a rosin-based tackifier having a softening point of 70 ° C (trade name: Harrier Star DS70E /
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive sheet was changed to Harima Chemicals.

Comparative Example 4 An adhesive sheet was obtained in the same manner as in Example 1 except that a rosin tackifier was not added in the production of the adhesive of Example 1.

Comparative Example 5 In the production of the pressure-sensitive adhesive of Example 1, a rosin tackifier having a softening point of 160 ° C. (trade name: Superester E)
-650 / Arakawa Chemical Co., Ltd.) An adhesive sheet was obtained in the same manner as in Example 1 except that 10 parts was changed to 30 parts.

Comparative Example 6 In the production of the release paper of Example 1, a polyethylene laminate obtained by laminating low-density polyethylene with a melt extruder on a high-quality paper of 80 g / m ² of 80 g / m ² of glassine paper of 83 g / m ² of rice. An adhesive sheet was obtained in the same manner as in Example 1 except that the type of release base paper was changed.

Comparative Example 7 In the preparation of the pressure-sensitive adhesive of Example 6, the surfactant polyoxyethylene lauryl ether (Emulgen 105 / Kao Co., Ltd.) used for polymerization of the pressure-sensitive adhesive was replaced with polyoxyethylene octyl phenyl ether (Emulgen 810). / Kao Co., Ltd.), except that the pressure-sensitive adhesive sheet was obtained in the same manner as in Example 6.

The following evaluation was performed on the pressure-sensitive adhesive sheet thus obtained, and the results are shown in Table 1. The evaluation method for each item is as follows. "Adhesive coating property" ：: Good coating surface is obtained without foaming or cissing of the adhesive. Δ: Foaming and repelling are slightly observed, but at a level that is not a problem in practical use. ×: Foaming and cissing were observed, and the coated surface was poor.

Suntech film (polyolefin film) of "adhesive to polyolefin wrap" adhesive sheet
The adhesiveness to the film was evaluated. ：: very strong adhesion. Δ: The label can be peeled off, but at a level that is practically acceptable. ×: The label is peeled off very easily.

"Bleeding on Surface Substrate" The pressure-sensitive adhesive sheet was treated in a 60 ° C. atmosphere under a pressure of 400 g / cm ² for one week, and the bleeding on the surface substrate was evaluated according to the following evaluation criteria. ：: No bleeding occurred. Δ: Slightly bleed, but at a level that does not cause any practical problem. X: The image was remarkably bleed and the recorded image was erased.

"Coloring property" Using a thermo-evaluator (TH-PMD, manufactured by Okura Electric Co., Ltd.), applied energy 0.4 mJ / do
At t, the heat-sensitive recording label was colored, and the color density of the obtained recorded image was measured in a visual mode using a Macbeth densitometer (RD-914, manufactured by Macbeth).

"White spot resistance" After the heat-sensitive recording label was treated at 60 ° C for 3 weeks, a hot plate at 120 ° C was pressed for 5 seconds (4k
g / cm ² ), and the white spots of the recorded image were visually judged. The evaluation criteria for the recording image quality were as follows. ：: No white spots are observed. C: White spots are slightly observed, but at a level that does not cause any practical problem. X: The white spot is remarkable.

[0085]

[Table 1]

[0086]

As is evident from the results in Table 1, the pressure-sensitive adhesive sheet of the present invention has good adhesiveness to a polyolefin wrap without foaming or cissing when the pressure-sensitive adhesive is applied. In addition, no harmful substances such as dioxin are generated when incinerated. Further, when the pressure-sensitive adhesive sheet of the present invention is used as a thermosensitive recording medium, there is no decrease in recording sensitivity of the thermosensitive recording medium, and no white spots occur in printing.

Claims (3)

[Claims] 1. A pressure-sensitive adhesive sheet having a surface substrate, a pressure-sensitive adhesive layer, a silicone-based release agent layer and a release base paper laminated in this order, wherein the pressure-sensitive adhesive layer and the release base paper satisfy the following conditions (1) and (2): Is simultaneously satisfied. (1) The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is formed by mixing a (meth) acrylate monomer or a mixture of a (meth) acrylate monomer and another copolymerizable monomer with a polyoxyethylene alkyl ether-based and / or polyoxyethylene A homopolymer and / or copolymer obtained by emulsion polymerization using a surfactant containing an ethylene alkyl ester as a main component is contained as a base polymer, and a softening point is 80 ° C. or higher based on 100 parts by weight of the base polymer. Is an acrylic emulsion pressure-sensitive adhesive containing 2 to 20 parts by weight of a rosin-based tackifier. (2) The release base paper is glassine type paper or a clay coated type paper provided with a coating layer mainly containing a pigment and a binder. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the surface substrate is a thermosensitive recording medium having a thermosensitive recording layer. 3. The color former in the heat-sensitive recording layer is 4,4'-bis (Np-trisulfonylurea) diphenylmethane, Np-tolylsulfonyl-N'-phenylurea, 4-hydroxy-4 ' At least one colorant selected from isopropoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone and 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether The pressure-sensitive adhesive sheet according to claim 2.