JP4769453B2 - Thermosensitive adhesive composition and thermosensitive adhesive label - Google Patents

Description

  The present invention is a heat-sensitive adhesive that is non-adhesive at room temperature but develops an adhesive property upon heating, and maintains the adhesive property for a while even after the heat source is removed, and a heat-sensitive adhesive comprising this adhesive It relates to an adhesive label sheet.

  In recent years, the use of pressure-sensitive adhesive sheets for labels such as labels for price display, labels for product display (barcode), labels for quality display, labels for weighing display, labels for advertising (stickers) has increased. ing. There are various recording methods such as an inkjet recording method, a thermal recording method, and a pressure sensitive recording method. Conventional general adhesive sheets have a structure in which an adhesive layer and release paper are laminated on the side opposite to the information recording surface of the label. Widely used because it can be combined. However, the pressure-sensitive adhesive sheet having a general configuration is used by peeling the release paper, but the peeled release paper is hardly collected and reused, and is almost always disposed of. Therefore, in recent years, attention has been paid to a heat-sensitive adhesive sheet that does not exhibit adhesiveness at room temperature and does not require a release paper.

  In addition, as described in Non-Patent Document 1, the thermoactive adhesive basically includes a thermoplastic resin, a heat-meltable substance such as a solid plasticizer, and a tackifier as necessary. It contains. Thermoplastic resins impart adhesive strength and adhesive strength, and heat-meltable substances are solid at room temperature and therefore do not impart plasticity to the resin, but they melt by heating to swell or soften the resin. To develop adhesiveness. The tackifier also works to improve the tackiness. Since the heat-meltable substance in the heat-activatable pressure-sensitive adhesive crystallizes slowly after being melted by heating, the pressure-sensitive adhesive lasts for a long time even after the heat source is removed.

  Nowadays, it is becoming a common recognition of mankind to run economies and production activities in consideration of environmental conservation. The Environment Agency reported about 70 chemical substances suspected of having endocrine disrupting effects in 1997. Of these about 70 chemicals, mention of phthalates is found. There is concern that phthalate esters, which are mainly used as plasticizers, are taken into the human body through the food chain, disrupting the hormonal balance in the body and adversely affecting reproductive functions. Conventionally, many of known heat-sensitive adhesives use a phthalate ester as a solid plasticizer, and there has been a demand for an alternative material.

  Thereafter, in Patent Documents 1 and 2, as a thermoplastic resin, an ethylene-vinyl acetate copolymer having a glass transition point of 0 ° C. or higher or a thermoplastic resin having a glass transition point of −5 ° C. or higher (ethylene-vinyl acetate copolymer). It has been proposed to use (excluding coalescence). However, although the adhesive strength to a stainless steel plate or the like has a relatively good result, the adhesive strength to PVC wrap, polyolefin wrap, cardboard, etc. has not yet reached a practical level. Patent Document 3 proposes a heat-sensitive adhesive material using a hindered phenol compound, a benzotriazole compound and an aromatic sulfonamide compound, and further using hollow particles having a hollow ratio of 50% in the under layer. Even those using this heat-sensitive adhesive material were not satisfactory in adhesiveness and blocking to vinyl chloride wrap, polyolefin wrap, cardboard and the like. In Patent Document 4, it has been proposed to improve the adhesive properties in the range from low temperature to normal temperature using solid plasticizers having different particle diameters, but they do not have sufficient adhesive strength to cardboard. The adhesive strength after raw storage of the sheet was greatly reduced.

  Moreover, an anionic emulsifier, a nonionic emulsifier, a water-soluble resin, or the like is used as a dispersant for the solid plasticizer. Examples of anionic emulsifiers include fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkyl sulfosuccinates, and alkyl phosphates. Nonionic emulsifiers include polyoxyethylene alkyl ethers and polyoxyethylene alkyl aryl ethers. , Polyoxyethylene / oxypropylene block polymer, sorbitan fatty acid, polyoxy fatty acid ester, polyoxyethylene alkylamine, and the like, and water-soluble resins include methylcellulose, polyvinyl alcohol, sodium polycarboxylic acid, maleic acid resin, gelatin and the like. Can be mentioned. Among these, when a surfactant having a high HLB value is used, foaming is likely to occur, leading to problems in the dispersion process, coating process, and the like. On the other hand, if a low HLB value that has antifoaming properties is used, foaming is less likely to occur, but the capacity of the dispersant is not sufficient, resulting in poor dispersion. Further, when the particle size is made finer, there is a problem that a circulation failure and a dispersion time in the disperser become long because of a whip-like process. In Patent Document 5, an example of nonylphenylalkylene ether is given as a nonionic surfactant, but there is a problem in foamability. Furthermore, Patent Document 6 proposes that a solid plasticizer benzoate is dispersed with a carboxylic acid-containing copolymer. However, although foaming property was suppressed, it was not sufficient depending on the process.

Also, when dispersing the solid plasticizer, depending on the type of the solid plasticizer, there may be cases where foaming occurs due to stirring in the circulation pump, resulting in a whip shape, such as a wire bar coater or roll coater. This causes defects in the coated surface and insufficient adhesive strength at the time of application. In particular, when a highly polar solid plasticizer is used, it is difficult to disperse and the above problems are likely to occur.
Japanese Patent No. 2914029 JP-A-6-57233 JP 2002-105414 A Japanese Patent Laid-Open No. 2001-064603 JP-A-8-333565 JP 2002-155264 A "Adhesion Handbook" 12th edition, pp. 131-135, published in 1970

  The present invention eliminates the problems found in conventional thermoactive adhesives, exhibits good stability in steps such as dispersion and coating of solid plasticizers, and is excellent in adhesive strength, even after raw storage, PVC wrap, polyolefin An object of the present invention is to provide a heat-sensitive adhesive composition in which a decrease in adhesive force to an adherend such as wrap and cardboard is small, and a heat-sensitive adhesive label sheet using the same.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a silicone surfactant as a dispersant for the solid plasticizer. Based on the knowledge that the adhesive strength after storage is difficult to decrease, the inventors have completed the inventions according to (1) to (12) described below.

That is,
(1) A heat-sensitive adhesive composition comprising a thermoplastic resin, a tackifier, and a solid plasticizer having a dispersant, wherein the dispersant is a silicone emulsion surfactant. Heat-sensitive adhesive composition. As a result, it is possible to provide a heat-sensitive adhesive composition that is free from defects in the dispersion process and the application process, has excellent adhesion to an adherend, and has stable adhesion after raw storage.

(2) The heat-sensitive adhesive composition according to (1) , wherein the dispersant is contained in an amount of 0.01 part to 0.5 part with respect to 100 parts by weight of the solid plasticizer. Thereby, in addition to the above, the heat-sensitive adhesive composition which suppressed foaming at the time of dispersion | distribution and maintained adhesive force can be obtained.

(3) The heat-sensitive adhesive composition according to (1) or (2) , wherein the average particle diameter of the solid plasticizer is 2.0 μm or more and 8.0 μm or less. Thereby, the heat-sensitive adhesive composition with stable adhesive strength after raw storage can be provided.

(4) The heat-sensitive adhesive composition according to any one of (1) to (3) , wherein the solid plasticizer contains at least one benzotriazole-based compound. As a result, it is possible to provide a heat-sensitive adhesive composition that is free from defects in the dispersion process and the application process, has excellent adhesion to an adherend, and has stable adhesion after raw storage.

(5) The thermosensitive adhesive composition according to any one of (1) to (4) , wherein a glass transition point of the thermoplastic resin is −70 ° C. or higher and −5 ° C. or lower. Thereby, in addition to the above-mentioned, in actual use conditions, the heat-sensitive adhesive composition which satisfy | fills both adhesive force and blocking property can be provided.

(6) A heat-sensitive adhesive label sheet, wherein the heat-sensitive adhesive composition according to any one of (1) to (5) is laminated on a first main surface of a support. Thereby, there can be provided a heat-sensitive pressure-sensitive adhesive label sheet which is free from problems in the dispersion process and the coating process, has excellent adhesive strength to the adherend and has stable adhesive strength after raw storage.

(7) The heat-sensitive adhesive label sheet according to (6) , further comprising an under layer having a thermoplastic resin between the heat-sensitive adhesive composition and the support. Thereby, in addition to the above-mentioned, by using an under layer, the reliability with respect to adhesive force and the heat-sensitive adhesive composition in which adhesion with low energy is attained can be provided.

(8) The heat-sensitive adhesive label according to (6) or (7) , further comprising a heat-sensitive recording layer containing a leuco dye and a developer on the second main surface of the support. Sheet. As a result, it is possible to provide a heat-sensitive adhesive label sheet that includes a simple heat-sensitive recording layer, has no problems in the dispersion process and the coating process, has excellent adhesion to the adherend, and has stable adhesion after raw storage.

(9) The heat-sensitive adhesive label sheet according to any one of (6) to (8) , which has an ink image developed with UV ink. This makes it possible to provide a heat-sensitive adhesive composition in which a sheet is preliminarily printed with a prescribed frame, logo, etc., which is practical.

(10) The heat-sensitive adhesive label sheet according to any one of (6) to (9) , further comprising a protective layer. As a result, it is possible to provide a heat-sensitive adhesive label sheet that is excellent in abrasion resistance, has no problems in the dispersion process and the application process, has excellent adhesion to the adherend, and has stable adhesion after raw storage.

(11) The heat-sensitive adhesive label sheet according to any one of (6) to (10) , which is wound around a core material in a roll shape. Thereby, in addition to the above-mentioned, the thermosensitive adhesive label sheet which can be handled easily can be provided.

(12) The heat-sensitive adhesive label sheet according to any one of (6) to (11) , which is wound in a roll shape without using a core material. Thereby, in addition to the above, the heat-sensitive adhesive label sheet which can be handled easily can be provided. Since no core material is required, it is possible to provide a heat-sensitive adhesive composition that can contribute to the reduction of dust.

  It is possible to provide a heat-sensitive adhesive composition that is free from defects in the dispersion step and the coating step, has excellent adhesive strength to adherends such as vinyl chloride wrap, polyolefin wrap, and cardboard, and also has stable adhesive strength after raw storage. Moreover, the heat sensitive adhesive label sheet produced using this heat sensitive adhesive composition contributes to the label field | area and environmental conservation.

  Below, the characteristic which concerns on the heat-sensitive adhesive label sheet of this invention is demonstrated in detail.

  The thermoplastic resin used in the heat-sensitive adhesive layer mainly composed of the thermoplastic resin, tackifier and solid plasticizer in the present invention is a natural rubber latex obtained by graft copolymerization with a vinyl monomer, and an acrylic ester copolymer. Methacrylic acid ester copolymer, acrylic acid ester-methacrylic acid ester copolymer, acrylic acid ester-styrene copolymer, acrylic acid ester-methacrylic acid ester-styrene copolymer, ethylene-vinyl acetate copolymer It is preferable to use at least one compound selected from the group.

The application amount of the heat-sensitive adhesive layer of the present invention is usually 5 to 35 g / m ² , preferably 10 to 25 g / m ² as a dry application amount. When the application amount of the heat-sensitive adhesive layer is less than 5 g / m ² , a sufficient adhesive force effect cannot be obtained when performing adhesion by heating. On the other hand, if it exceeds 35 g / m ² , the adhesive strength is saturated, which is not economical.

  The content of the thermoplastic resin in the heat-sensitive adhesive layer is preferably 15 to 50% by weight, more preferably 20 to 50% by weight. When the content of the thermoplastic resin is less than 15% by weight, any of them is not desirable because the adhesive strength is lowered. Moreover, when the content rate of a thermoplastic resin exceeds 50 weight%, the malfunction on storage (blocking) will arise, such as adhesive force developing at the temperature under normal storage environment.

  As the solid plasticizer in the present invention, a compound that is solid at room temperature and melts when heated is used. The melting point thereof is preferably 70 ° C. or higher, more preferably 80 ° C. or higher, and the upper limit is about 200 ° C. When the melting point is less than 70 ° C., storage defects such as an adhesive force appearing at a normal storage environment temperature when used as a heat-sensitive adhesive will occur. In addition, there may be a problem in production such as an adhesive force when the heat-sensitive adhesive coating solution is applied to the support and dried. When the melting point exceeds 200 ° C., a large amount of energy is required to develop the adhesive force, resulting in practical problems. In addition, when a heat-sensitive recording paper is used as a support and an adhesive force is developed with a large amount of energy, there is a problem that a printed image cannot be read because the heat-sensitive recording layer is colored.

  In the heat-sensitive adhesive layer of the present invention, the content of the solid plasticizer in the thermally active adhesive is preferably 25 to 80% by weight, and more preferably 40 to 75% by weight. When the content of the solid plasticizer is less than 25% by weight, when combined with a thermoplastic resin, storage problems such as the occurrence of adhesive strength under normal storage environment temperatures (blocking) occur, exceeding 80% by weight If this happens, the adhesive strength may decrease.

  Next, the solid plasticizer used in the heat-sensitive adhesive layer of the present invention is 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl). Benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-amyl) Phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-t-butylphenyl) -5-chlorobenzotriazole, 2- [2′-hydroxy-3 ′, 5′-di (1,1) -Dimethylbenzyl) phenyl] benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-sec Butyl-5'-t-butylphenyl) benzotriazole and the like, may be used by mixing these benzotriazoles two or more.

  Further, as the eutectic agent used in the heat-sensitive adhesive layer of the present invention, a solidifying agent that is solid at room temperature and melts when heated is used. The melting point of these compounds is preferably 70 ° C. or higher, more preferably 80 ° C. or higher, and the upper limit is about 150 ° C. When the melting point is less than 70 ° C., storage defects such as an adhesive force appearing at a normal storage environment temperature when used as a heat-sensitive adhesive will occur. In addition, there may be a problem in production such as an adhesive force when the heat-sensitive adhesive coating solution is applied to the support and dried. On the other hand, when the melting point exceeds 150 ° C., the effect of eutecticizing the solid plasticizer is lost.

  In the heat-sensitive adhesive layer according to the present invention, a supercooling accelerator that promotes the supercooling property of the solid plasticizer and develops high adhesive force in a low temperature environment in addition to the thermoplastic resin and the solid plasticizer is used. Can do. Examples include naphthol derivatives such as 2-benzyloxynaphthalene, biphenyl derivatives such as metaterphenyl, acetylbiphenyl, p-benzylbiphenyl or 4-allyloxybiphenyl, 1,2-bis (3-methylphenoxy) ethane, 2, Polyether compounds such as 2′-bis (4-methoxyphenoxy) diethyl ether or bis (4-methoxyphenyl) ether or diphenyl carbonate, dibenzyl oxalate, di (p-chlorobenzyl) oxalate ester or dioxalate (p Carbonic acid or oxalic acid diester derivatives such as -methylbenzyl) esters may be mentioned, and two or more of these may be used in combination. Among them, dibenzyl oxalate derivatives and biphenyl derivatives have the effect of promoting the supercooling property of the solid plasticizer.

  A silicone emulsion surfactant is used as a dispersant for the solid plasticizer, which is an essential component of the present invention. Examples of the silicone emulsion surfactant include emulsions of polyoxyethylene / methylpolysiloxane copolymer, polyoxypropylene / methylpolysiloxane copolymer, methylpolysiloxane, dimethylpolysiloxane and the like. Moreover, you may mix | blend a metal oxide, an inorganic filler, an organic filler, etc. with these emulsions. The addition amount of the silicone emulsion surfactant is preferably 0.01 to 0.5 part with respect to 100 parts by weight of the solid plasticizer. This is because the mechanism is not elucidated, but there is a feature that there is little decrease in the adhesive strength to adherends such as cardboard after raw storage. When this addition amount is less than 0.01 part, the effect as a surfactant cannot be expected, foaming at the time of dispersion cannot be suppressed, and the time to reach a predetermined particle size becomes long. On the other hand, when it is larger than 0.5 part, the adhesive force is lowered, and when an under layer is present, a large repellency is generated when the heat-sensitive adhesive layer is applied.

  Furthermore, in order to improve the adhesive strength of the heat-sensitive adhesive layer, a tackifier may be added to the heat-sensitive adhesive layer. Examples of such tackifiers include various commonly used compounds. For example, rosin derivatives, terpene resins, petroleum resins, phenol resins, and xylene resins that are tackifiers may be used.

  As a tackifier particularly preferably used for the heat-sensitive adhesive of the present invention, a rosin derivative (rosin, polymerized rosin, hydrogenated rosin) or a terpene resin (terpene resin, aromatic modified terpene resin, terpene phenol resin, hydrogenated) Terpene resin). These tackifiers are compatible with the thermoplastic resin and the hot-melt material of the present invention, and the adhesive strength of the heat-sensitive adhesive is significantly improved. Moreover, the melting point or softening point of the tackifier in the heat-sensitive adhesive is preferably 80 ° C. or higher, and more preferably 80 to 200 ° C. When the temperature is less than 80 ° C., storage defects (decrease in blocking resistance) occur at normal storage environment temperatures. Moreover, when it exceeds 200 degreeC, compatibility with a thermoplastic resin worsens and the effect which got stuck cannot be acquired. On the other hand, the content of the tackifier in the heat-sensitive adhesive is preferably 1 to 30% by weight, and more preferably 1 to 20% by weight. If it is less than 1% by weight, the adhesive strength is remarkably reduced, and if it exceeds 30% by weight, storage problems at normal temperatures (decrease in blocking resistance) and initial adhesive strength at low temperatures are reduced. Occurs.

  In the heat-sensitive adhesive of the present invention, in addition to the above components, in order to prevent blocking, inorganic substances such as titanium oxide, alumina, colloidal silica, kaolin, talc, stearic acid metal salts, paraffin, natural wax, synthetic wax, Organic substances such as natural fats and oils and polystyrene powder may be added, and if necessary, a dispersant, an antifoaming agent, a thickener and the like may be used.

  The thermoplastic resin used in the under layer between the heat-sensitive adhesive layer and the support of the present invention is a (meth) acrylic acid ester copolymer, a styrene-isoprene copolymer, or a styrene-acrylic acid ester copolymer. Resins such as polymer, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, vinyl acetate-acrylate copolymer, ethylene-acrylate copolymer, vinyl acetate-ethylene-acrylate copolymer Preferably, the Tg of the thermoplastic resin is −70 to −5 ° C. Even when it is used for the under layer, if it is lower than −70 ° C., the blocking property tends to be lowered, and if it is higher than −5 ° C., the adhesive force is not improved. On the other hand, if necessary, it can contain fillers, inorganic or organic fillers such as calcium carbonate, silica, titanium oxide, aluminum hydroxide, clay, calcined clay, magnesium silicate, magnesium carbonate, white carbon, zinc oxide, Barium sulfate, surface-treated calcium carbonate, silica, etc., urea-formalin resin, styrene / methacrylic acid copolymer, fine powder such as polystyrene, hollow filler, etc. can be used, but are not limited thereto. .

  The heat-sensitive adhesive material of the present invention, in which a heat-sensitive adhesive layer using a silicone emulsion surfactant as a solid plasticizer dispersant is provided on one side of a support, solves problems in the production process, and each deposition It is possible to obtain a heat-sensitive pressure-sensitive adhesive label sheet having a strong adhesive force to an adherend such as vinyl wrap, polyolefin wrap and cardboard, and also having good adhesive strength after raw storage.

  Drying conditions for coating or printing on the support must be such that the hot-melt material and the eutectic agent used do not melt. As a means for drying, in addition to hot air drying, a drying method using a heat source using infrared rays, microwaves, and high frequencies can be used.

  In the heat-sensitive recording layer of the present invention, a heat-sensitive recording layer mainly comprising a leuco dye and a developer can be formed on the support. As the leuco dye used in the heat-sensitive recording layer of the present invention, a leuco dye known in this type of leuco recording material is generally applied. For example, triphenylmethane, fluorane, phenothiazine, auramine, spiropyran And leuco compounds of dyes such as indolinophthalide are preferably used. Specific examples of such leuco dyes include 3,3-bis (p-dimethylaminophenyl) phthalide and 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also called crystal violet lactone). 3,3-bis (p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7 , 8-Benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane 3- (Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'- Trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2- {3,6-bis (diethylamino) -9- (o-chloroanilino) xanthylbenzoate lactam}, 3-diethylamino-6-methyl-7- ( m-trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-N-methyl-N-amylamino-6-methyl- 7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethy Amino-6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluorane, benzoylleucomethylene blue, 6'-chloro-8 '-Methoxy-benzoindolino-pyrospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrospirane, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy- 5′-chlorophenyl) phthalide, 3- (2′-hydroxy-4′-dimethylaminophenyl) -3- (2′-methoxy-5′-nitrophenyl) phthalide, 3- (2′-hydroxy-4 ′) -Diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluorane, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3-morpholino- 7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) Fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-toluidino) ) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenyl) Amino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane, 2-chloro-3- (N-methyltoluidino) -7- ( p-n-butylanilino) fluorane, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4′-bromofluorane, 3-diethylamino-6-methyl-7 -Mesitidino-4 ', 5'-benzofluorane, 3-diethylamino-6-methyl-7- (2', 4'-dimethylanilino) fluorane, 3- (p-dimethylaminophenyl) -3- {1 , 1-bis (p-dimethylaminophenyl) ethylene-2-yl} phthalide, 3- (p-dimethylaminophenyl) -3- {1,1-bis (p -Dimethylaminophenyl) ethylene-2-yl} -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-phenylethylene-2-yl) phthalide 3- (p-dimethylaminophenyl-3- (1-p-dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide, 3- (4′-dimethylamino-2) '-Methoxy) -3- (1 ″ -p-dimethylaminophenyl-1 ″ -p-chlorophenyl-1 ″, 3 ″ -butadiene-4 ″ -yl) benzophthalide, 3- (4′- Dimethylamino-2′-benzyloxy) -3- (1 ″ -p-dimethylaminophenyl-1 ″ -phenyl-1 ″, 3 ″ -butadiene-4 ″ -yl) Zophthalide, 3-dimethylamino-6-dimethylamino-fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3,3-bis {2- (p-dimethylaminophenyl) -2- (p -Methoxyphenyl) ethenyl} -4,5,6,7-tetrachlorophthalide, 3-bis {1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl} -5,6-dichloro-4 , 7-dibromophthalide, bis (p-dimethylaminostyryl) -1-naphthalenesulfonylmethane, 3- (N-methyl-N-propylamino) -6-methyl-7-anilidefluorane, 3-diethylamino-6 -Methyl-7-anilinofluorane, 3,6-bis (dimethylamino) fluorane spiro (9,3 ')-6'-dimethylaminophthalide, 3-diethylamino -6-chloro-7-anilinofluorane, 3-N-ethyl-N- (2-ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfuryl Amino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino-4 ', 5'-benzofluorane, 3-N-methyl-N-isobutyl-6-methyl-7 -Anilinofluorane, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, etc. can be mentioned.

  In the heat-sensitive recording layer of the present invention, various electron-accepting compounds such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof can be applied as color developers. it can. Specific examples thereof include 4,4′-isopropylidene bisphenol, 3,4′-isopropylidene bisphenol, 4,4′-isopropylidene bis (o-methylphenol), 4,4′-sec-butylidene bisphenol, 4,4′-isopropylidenebis (ot-butylphenol), 4,4′-cyclohexylidenediphenol, 4,4′-isopropylidenebis (2-chlorophenol), 2,2′-methylenebis (4- Methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-butylidenebis (6-tert-butyl-2-methyl) phenol, 1,1, 3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,1,3-tris (2-methyl 4-hydroxy-5-cyclohexylphenyl) butane, 4,4′-thiobis (6-tert-butyl-2-methyl) phenol, 4,4′-diphenolsulfone, 4,2′-diphenolsulfone, 4- Isopropoxy-4′-hydroxydiphenylsulfone, 4-benzyloxy-4′-hydroxydiphenylsulfone, 4,4′-diphenol sulfoxide, isopropyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, benzyl protocatechuate, gallic acid Stearyl, lauryl gallate, octyl gallate, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -3-oxaheptane, 1 , 3-bis (4-hydroxyphenylthio) -propane, 2, '-Methylenebis (4-ethyl-6-tert-butylphenol), 1,3-bis (4-hydroxyphenylthio) -2-hydroxypropane, N, N'-diphenylthiourea, N, N'-di (m -Chlorophenyl) thiourea, salicylanilide, 5-chloro-salicylanilide, salicyl-o-chloroanilide, 2-hydroxy-3-naphthoic acid, antipyrine complex of zinc thiocyanate, zinc of 2-acetyloxy-3-naphthoic acid Salts, 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid zinc, aluminum, calcium, etc., bis- (4-hydroxyphenyl) acetic acid methyl ester, bis- (4 -Hydroxyphenyl) acetic acid benzyl ester, 4- {β- (p-methoxyphenoxy) ethoxy } Salicylic acid, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 2,4′-diphenolsulfone, 3,3′-diallyl-4,4 '-Diphenolsulfone, antipyrine complex of α, α-bis (4-hydroxyphenyl) -α-methyltoluenethiocyanate, tetrabromobisphenol A, tetrabromobisphenol S, 4,4'-thiobis (2-methylphenol) ), 3,4-hydroxy-4′-methyl-diphenylsulfone, 4,4′-thiobis (2-chlorophenol), and the like.

  In order to form the heat-sensitive recording layer of the present invention, a leuco dye and a developer may be bonded and supported on a support. In this case, various conventional binders can be used as appropriate. Examples of such binders include polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, polyacrylic acid soda, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer Water-soluble compounds such as acrylamide / acrylic acid ester / methacrylic acid terpolymers, styrene / maleic anhydride copolymer alkali salts, isobutylene / maleic anhydride copolymer alkali salts, polyacrylamide, sodium alginate, gelatin, casein, etc. In addition to functional polymers, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester, polymethacrylic acid ester, polybutyl methacrylate, vinyl chloride / acetic acid Cycloalkenyl copolymer, ethylene / emulsion and styrene / butadiene copolymer vinyl acetate copolymer, it can be mentioned latices such as styrene / butadiene / acrylic copolymer.

  Further, when the heat-sensitive recording layer is formed according to the present invention, various heat-fusible substances can be used as fillers. Specific examples thereof include fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, and fatty acids such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate. Metal salts, p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, β-naphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid phenyl ester, 1-hydroxy 2-naphthoic acid methyl ester, diphenyl carbonate, terephthalic acid dibenzyl ester, terephthalic acid dimethyl ester, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1, 2-bis (phenoxy) ethane, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1,4-bis (phenoxy) butane, 1,4-bis ( Phenoxy) -2-butene, 1,2-bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,4-bis (phenylthio) butane, 1,4-bis (phenylthio) -2-butene, 1, 2-bis (4-methoxyphenylthio) ethane, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2-vinyloxyethoxy) biphenyl , P-aryloxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, 1,3-dibenzoyloxypropane, dibenzyldi Rufide, 1,1-diphenylethanol, 1,1-diphenylpropanol, p- (benzyloxy) benzyl alcohol, 1,3-diphenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoyl Benzene, oxalic acid dibenzyl ester, 1,5-bis (p-methoxyphenyloxy) -3-oxapentane and the like can be mentioned.

  In the present invention, auxiliary additives commonly used in this type of heat-sensitive recording layer, such as surfactants and lubricants, can be used in combination as required. In this case, examples of the lubricant include higher fatty acids and metal salts thereof, higher fatty acid amides, higher fatty acid esters, animal, vegetable, mineral and petroleum-based waxes.

  In the present invention, for example, a water-soluble resin is used for the purpose of providing an undercoat layer between the support and the heat-sensitive recording layer or improving the image reliability on the heat-sensitive recording layer, if necessary. A protective layer as a main component can be provided, and a back coat layer can also be provided on the back surface of the support. In this case, as the components constituting these layers, the above-mentioned fillers, binders, thermofusible substances, surfactants and the like can be used. Further, when the protective layer and the protective layer are not provided, a printed image can be formed directly on the thermal recording layer. As the printing ink, for example, the UV curable ink is quick-drying, so that the thermal recording is performed. It is used as an optimal ink for paper.

  The heat-sensitive recording layer of the present invention can be formed by a generally known method. For example, first, the leuco dye and the developer are separately pulverized and dispersed together with an aqueous binder solution by a dispersing machine such as a ball mill, an attritor, or a sand mill until the dispersed particle size becomes 1 to 3 μm, and a filler as required. A heat-sensitive recording layer can be formed by preparing a heat-sensitive recording layer coating solution by mixing with a heat-fusible substance (sensitizer) dispersion and the like, and applying it to a support.

  The base paper preferably used for the support according to the present invention is composed mainly of wood pulp and filler. Wood pulp includes chemical pulps such as LBKP and NBKP, mechanical pulps such as GP, PGW, RMP, TMP, CTMP, CMP, and CGP, and pulps such as waste paper pulp such as DIP. , Binder, sizing agent, fixing agent, yield improver, cationizing agent, paper strength enhancer, etc. are mixed using one or more kinds of additives, long net paper machine, circular net paper machine, twin wire paper machine, etc. The support can be produced with various devices, and can be made in an acidic, neutral or alkaline paper. In addition, this base paper may be subjected to on-machine treatment with a calender device composed of a metal roll and a synthetic resin roll. At that time, off-machine processing may be performed, and after processing, the flatness may be controlled by further performing calendar processing with a machine calendar, a super calendar, or the like.

  Examples of the filler contained in the base paper include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, satin white, aluminum silicate, diatomaceous earth, calcium silicate, White inorganic pigments such as magnesium silicate, synthetic silica, aluminum hydroxide, alumina, lithopone, zeolite, magnesium carbonate, magnesium hydroxide, styrene plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin, melamine resin Such organic pigments can be mentioned. Examples of the sizing agent contained in the base paper include a rosin sizing agent for acidic papermaking, a modified rosin sizing agent for neutral papermaking, AKD, ASA, and a cationic polymer sizing agent. As the support according to the present invention, general paper such as glassine paper, art paper, coated paper, cast paper, and the like can be used. Fillers, sizing agents, paper strength enhancers, dyes, etc., raw materials usually used in papermaking Can be used as needed. Plastic sheets such as polyethylene, polypropylene, polyethylene terephthalate, and polyamide, and synthetic paper or nonwoven fabric made of these synthetic fibers, or laminated paper in which synthetic resin is laminated on one side or both sides, metal foil, or metal foil and paper, It is also possible to use vapor-deposited paper, an opaque sheet subjected to hologram processing, a bonded product with a synthetic resin film, mica paper, glass paper, and the like.

  As a coating method for providing the thermosensitive coloring layer, intermediate layer, protective layer and thermosensitive adhesive layer of the thermosensitive recording material of the present invention, a blade coater, a gravure coater, a gravure offset coater, a bar coater usually used for paper coating Roll coater, knife coater, air knife coater, comma coater, U comma coater, AKKU coater, smoothing coater, micro gravure coater, reverse roll coater, 4 or 5 roll coater, dip coater, falling curtain coater, slide coater, die coater Etc., or using various printing machines such as flexo, letterpress, gravure, offset, etc., coating and printing on the support. The drying conditions at the time of coating or printing on the support must be such that the solid plasticizer used does not melt. As a means for drying, in addition to hot air drying, a drying method using a heat source using infrared rays, microwaves, and high frequencies can be used.

  Further, a pre-printed layer can be provided on the opposite surface (surface) of the heat-sensitive recording material of the present heat-sensitive recording material, or eye mark printing as a sensing means can be provided on the surface or the heat-sensitive adhesive layer surface. . Both printing methods include general printing methods such as UV printing, EB printing, and flexographic printing.

  Furthermore, the heat-sensitive pressure-sensitive adhesive label sheet produced using the heat-sensitive pressure-sensitive adhesive composition according to the present invention may be wound around a known core material in a roll shape, and may be rolled without using a core material. It may be.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, all the parts and% shown below are based on weight.

Example 1
(1) Preparation of dye dispersion (hereinafter abbreviated as Liquid A) Composition comprising 20 parts of 3-dibutylamino-6-methyl-N-7-anilinofluorane, 20 parts of 10% aqueous solution of PVA, and 60 parts of water. The product was dispersed with a sand mill until the average particle size became 0.5 μm.

(2) Preparation of developer dispersion (hereinafter abbreviated as B solution) 4-isopropoxy-4′-hydroxydiphenylsulfone 20 parts, di- (p-methylbenzyl) oxalate 10 parts, calcium carbonate 10 parts, PVA A composition comprising 30 parts of a 10% aqueous solution and 30 parts of water was dispersed with a ball mill until the average particle size became 0.5 μm.

(3) Preparation of thermosensitive coloring layer coating solution A part 20 parts, B part 60 parts, carboxy-modified PVA (solid content 10%, KL-318, manufactured by Kuraray Co., Ltd.), dioctylsulfosuccinic acid aqueous solution (solid content 5%) ) A composition comprising 1 part was mixed to prepare a thermosensitive coloring layer coating solution.

(4) Preparation of coating liquid for protective layer 40 parts of aluminum hydroxide dispersion (solid content 50%), 6 parts of zinc stearate dispersion (solid content 30%), 1 part of dioctylsulfosuccinic acid aqueous solution (solid content 5%) , PVA having a diacetone group (diacetone monomer unit content 4%, polymerization degree 1600, saponification degree 98%, manufactured by Shin-Etsu Chemical Co., Ltd.) 200% aqueous solution, adipic acid hydrazide (crosslinking agent) aqueous solution (solid content 10%) A composition composed of 10 parts and 43 parts of water was mixed to prepare a protective layer coating solution.

(5) Application of heat-sensitive color developing layer and protective layer A heat-sensitive color developing layer coating solution is applied on a support (high-quality paper having a basis weight of about 60 g / m ² ) so that the dry weight of the dye is about 0.6 g / m ^2. The coating was dried to form a thermosensitive coloring layer. Then, a protective layer coating solution was applied and dried so that the dry adhesion weight was about 3 g / m ^2, and a calendar process was performed so that the smoothness of the protective layer surface was 5000 seconds.

(6) Preparation of solid plasticizer dispersion 100 parts 2- (3′-t-butyl-5′-methyl-2′-hydroxyphenyl) -5-chlorobenzotriazole, 50 parts polyvinyl alcohol 10% solution Then, 0.05 part of a silicone emulsion surfactant SND-382 (manufactured by San Nopco) and 200 parts of water are uniformly mixed and dispersed using a ball mill until the average particle size becomes 2.0 μm. Obtained. In the dispersion process, the state of the dispersion was visually confirmed, and the stability of the dispersion after dispersion was further confirmed with a homomixer (10000 rpm, 5 minutes) manufactured by Tokushu Kika Kogyo Co., Ltd.

(7) Preparation of thermosensitive adhesive liquid 100 parts of thermoplastic resin emulsion AP5570 (acrylic acid-2-ethylhexyl resin main component, Showa High Polymer Co., Ltd., solid content 55%, glass transition point -65 ° C.) as a tackifier Emulsion E100 (terpene phenol main component, manufactured by Arakawa Chemical Co., Ltd., solid content 50%, softening point 145 ° C.) 70 parts, hollow filler dispersion liquid 20 parts, the above-mentioned solid plasticizer dispersion liquid 540 parts, nonionic surfactant A heat-sensitive adhesive liquid was prepared by sufficiently stirring and mixing Olfine PD-001 (manufactured by Nissin Chemical Industry Co., Ltd.) at a ratio of 0.5 part and 90 parts of water.

(8) Application of heat-sensitive adhesive liquid The heat-sensitive adhesive liquid was applied to the opposite surface of the heat-sensitive recording layer of (5) above so that the dry adhesion amount was 15 g / m ² and dried to obtain the heat-sensitive recording material of the present invention. .

(Example 2)
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that 0.3 part of the solid plasticizer dispersant was used.

(Example 3)
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the average particle size of the dispersion of (6) solid plasticizer in Example 1 was 6.0 μm.

Example 4
(9) Preparation of hollow filler dispersion Plastic spherical hollow particle Matsumoto Microsphere R-300 (acrylonitrile / methacrylonitrile / isobornyl methacrylate copolymer, solid content concentration 33%, average particle size 3.0 μm, hollow ratio 90 %, Made by Matsumoto Yushi) 24 parts, 1.6 parts of surfactant Dapro W-77 (made by Elementis Japan) and 74.4 parts of water were stirred and dispersed to prepare a hollow filler dispersion.

(10) Preparation of under liquid The under liquid was prepared by stirring thermoplastic resin emulsion AP5570100 parts and hollow filler dispersion 30 parts.

The heat-sensitive material of the present invention was the same as in Example 1 except that the under-liquid was applied and dried as an under layer so that the dry adhesion amount was 20 g / m ² between the support of Example 1 and the heat-sensitive adhesive layer. A recording material was obtained. In addition, it visually confirmed about the repellency at the time of apply | coating a heat-sensitive adhesive liquid.

(Example 5)
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 4 except that the average particle size of the dispersion of (6) solid plasticizer in Example 1 was 6.0 μm.

(Example 6)
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the dispersant of (6) solid plasticizer in Example 1 was changed to silicone emulsion surfactant SH5507 (manufactured by Toray Dow Corning Silicone).

(Example 7)
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 2 except that (6) the dispersant for the solid plasticizer in Example 1 was changed to silicone emulsion surfactant SH5507 (manufactured by Toray Dow Corning Silicone).

(Example 8)
The heat-sensitive recording material of the present invention was obtained in the same manner as in Example 4 except that (6) the solid plasticizer dispersant in Example 1 was changed to silicone emulsion surfactant SH5507 (manufactured by Toray Dow Corning Silicone).

Example 9
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 5, except that the silicone emulsion surfactant SH5507 (manufactured by Toray Dow Corning Silicone) was used as the dispersant for the solid plasticizer in Example 1 (6).

(Comparative Example 1)
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 4 except that the amount of the dispersant (6) in Example 1 was 0.6 parts.

(Comparative Example 2)
A heat-sensitive recording material of a comparative example was obtained in the same manner as in Example 4 except that the average particle size of the dispersion of (6) solid plasticizer in Example 1 was 1.0 μm.

(Comparative Example 3)
The heat-sensitive recording material of the present invention was obtained in the same manner as in Example 4 except that (6) the dispersant for the solid plasticizer in Example 1 was changed to acetylene glycol surfactant Olfine PD-001 (manufactured by Nissin Chemical Industry). It was.

(Comparative Example 4)
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 4 except that the dispersant for the solid plasticizer in Example 1 (6) was the sulfosuccinate surfactant Newcol 290M (manufactured by Nippon Emulsifier).

<Adhesive strength>
Regarding the heat-sensitive recording materials produced in this example and the comparative example, a material that was stored for one day in a standard state (23 ° C. and 65%) and a material that was stored for two weeks in a 40 ° C. DRY environment after production were 4 cm wide and 10 cm long. Silicone system with thermal head (TH-0976SP manufactured by TEC) 8 dots / mm, resistance 500Ω, all dots energized, active energy 26.0 mJ / mm ² , printing speed 100 mm / second, diameter 1 cm The platen was activated by bringing the surface of the heat-sensitive adhesive layer into contact with the thermal head under the pressure of 6 kgf / line. Subsequently, it was affixed to the adherend (cardboard, polyolefin wrap) in the longitudinal direction with a 2 kg pressure rubber roller and peeled after 2 minutes under the conditions of a peeling angle of 180 degrees and a peeling speed of 300 mm / min. The adhesive strength at that time was measured with a force gauge, and the data were read and averaged at intervals of 0.1 seconds. The unit is gf / 25 mm. This test was carried out under standard conditions (23 ° C. 65%).

<Blocking property>
The surface of the heat-sensitive recording layer of the same sample was brought into contact with the surface of the heat-sensitive adhesive layer, tested at 200 g / cm ² at 50 ° C. under dry conditions for 24 hours, left at room temperature, and then the sample was peeled off. The blocking property was evaluated according to the rank as shown in Table 1 below.

  Table 1

  With respect to the above Examples 1 to 9 and Comparative Examples 1 to 4, the above-described evaluation was performed, and the results are shown in Table 2.

  Table 2

Claims (9)

A thermosensitive adhesive composition comprising a thermoplastic resin containing an acrylate copolymer , a tackifier, and a solid plasticizer containing a dispersant and a benzotriazole-based compound ,
The dispersant is a silicone emulsion surfactant.
The dispersant contains 0.01 part or more and 0.5 part or less with respect to 100 parts by weight of the solid plasticizer,
The heat-sensitive adhesive composition, wherein the solid plasticizer has an average particle size of 2.0 μm or more and 8.0 μm or less . 2. The thermosensitive adhesive composition according to claim 1, wherein a glass transition point of the thermoplastic resin is −70 ° C. or more and −5 ° C. or less. A heat-sensitive adhesive label sheet, wherein the heat-sensitive adhesive composition according to claim 1 or 2 is laminated on a first main surface of a support. The thermosensitive adhesive label sheet according to claim 3, further comprising an under layer having a thermoplastic resin between the thermosensitive adhesive composition and the support. The heat-sensitive adhesive label sheet according to claim 3 or 4, further comprising a heat-sensitive recording layer containing a leuco dye and a developer on the second main surface of the support. The heat-sensitive adhesive label sheet according to any one of claims 3 to 5, which has an ink image developed with UV ink. It has a protective layer, The heat-sensitive adhesive label sheet as described in any one of Claims 3 thru | or 6 characterized by the above-mentioned . The heat-sensitive adhesive label sheet according to any one of claims 3 to 7, wherein the heat-sensitive adhesive label sheet is wound around a core material in a roll shape. The heat-sensitive adhesive label sheet according to any one of claims 3 to 7, wherein the heat-sensitive adhesive label sheet is wound in a roll shape without using a core material.