JP5122101B2 - Heat-sensitive adhesive composition and heat-sensitive adhesive label sheet - Google Patents

Description

  The present invention is a heat-sensitive adhesive composition 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 after the onset of adhesiveness. It relates to a heat-sensitive 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.
Even heat-sensitive adhesive materials having such advantages have some problems with conventional ones.
One of the problems is blocking. Blocking is a phenomenon that develops adhesiveness even though the adhesive is not intended, and may be induced when exposed to a temperature atmosphere higher than room temperature for a long time. In either the roll state or the state where it is cut into a single sheet and stacked, once blocking is induced, the heat-sensitive adhesive layer and the outer surface (the surface opposite to the heat-sensitive adhesive layer across the support) ) Will not only interfere with paper feeding but also adversely affect printing on the outer surface.

Therefore, as a means for preventing blocking, a method of blending a wax having slipperiness in the heat-sensitive adhesive (Patent Document 1), the surface of the solid plasticizer is protected with an inorganic compound or colloid particles, and the softening of the solid plasticizer is performed. A method (Patent Document 2, Patent Document 3, Patent Document 4) and the like for preventing blocking by suppressing the above are disclosed. However, when a wax is blended, the anti-blocking effect is insufficient, and conversely, the tackiness is lowered. If the surface of the solid plasticizer is protected with inorganic compounds or colloidal particles, it takes time to melt and diffuse the solid plasticizer, and the stickiness of the heat-sensitive adhesive is unlikely to appear, resulting in problems such as a decrease in adhesive performance. Inadequate. In addition, blocking is improved by using a high melting point plasticizer, but side effects such as a significant decrease in adhesive strength occur, and it is transported and stored under low temperature conditions where blocking does not actually occur. The current situation is.
In Patent Documents 5 and 6, 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). It has been proposed to use (excluding copolymers). However, these have relatively good adhesion to stainless steel plates, but the adhesion to rough surface adherends such as corrugated cardboard has not yet reached a practical level. Patent Document 7 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 tackiness and blocking on rough surface adherends such as cardboard.
In addition, an anionic emulsifier, a nonionic emulsifier, a water-soluble resin, and the like are used as a dispersant for the solid plasticizer, and Patent Document 8 gives an example of sodium dioctylsulfosuccinate, but there is a problem with foaming properties. is there. Further, Patent Document 9 proposes to disperse a benzoic acid ester of a solid plasticizer with a carboxylic acid-containing copolymer, but it is not practically satisfactory in terms of blocking properties. Moreover, in patent document 10 and patent document 11, although polyvinyl alcohol is used as a dispersing agent of a solid plasticizer, it cannot be said enough about the adhesive force to a rough surface adherend like a corrugated cardboard.

Japanese Examined Patent Publication No. 62-21835 JP-A-6-57223 Japanese Patent Laid-Open No. 6-100907 Japanese Patent Application Laid-Open No. 6-100848 Japanese Patent No. 2914029 JP-A-6-57233 JP 2002-105414 A Japanese Patent Laid-Open No. 2003-216047 JP 2002-155264 A JP 2004-211004 A JP-A-2005-002313 "Adhesion Handbook" 12th edition, pages (131-135), published in 1970

  The object of the present invention is to provide a heat-sensitive pressure-sensitive adhesive label sheet that eliminates the problems found in conventional heat-activatable pressure-sensitive adhesive compositions, has excellent adhesion to rough surface adherends such as cardboard, and has good blocking properties. It is to be.

The first of the present invention is a heat-sensitive adhesive composition comprising a thermoplastic resin, a tackifier, and a solid plasticizer containing a dispersant, wherein the dispersant has a weight average molecular weight of 11000 to 39000 . Ri rate of 70% or more of polyvinyl alcohol resin der relates thermosensitive adhesive composition characterized by containing the dispersant 2-10 parts by weight with respect to the solid plasticizer to 100 parts by weight.
The second of the present invention, the glass transition point of the thermoplastic resin is about thermosensitive adhesive composition according to claim 1, characterized in that at -65 ° C. or higher -5 ° C. or less.
3rd of this invention is related with the heat-sensitive adhesive label sheet | seat characterized by laminating | stacking the heat-sensitive adhesive composition of Claim 1 or 2 on the 1st main surface of a support body.
4th of this invention was further equipped with the underlayer containing a thermoplastic resin between the said thermosensitive adhesive composition and the said support body, The thermosensitive adhesive label of Claim 3 characterized by the above-mentioned. Regarding the sheet.
The fifth of the present invention, on the second major surface of the support, the heat-sensitive according to claim 3 or 4, further comprising a heat-sensitive recording layer containing a leuco dye and the developer The present invention relates to an adhesive label sheet.
6th of this invention is related with the heat-sensitive adhesive label sheet of Claim 3 or 4 which has an ink image developed with UV ink on the 2nd main surface of the said support body.
7th of this invention is related with the heat-sensitive adhesive label sheet in any one of Claims 3-6 by which the heat-sensitive adhesive label sheet was wound by roll shape.
The eighth of the present invention relates to the heat-sensitive adhesive label sheet according to claim 7 , wherein the heat-sensitive adhesive label sheet is wound around the core material in a roll shape.

Below, the characteristic which concerns on the heat-sensitive adhesive label sheet of this invention is demonstrated in detail.
The heat-sensitive pressure-sensitive adhesive label sheet of the present invention is a heat-sensitive pressure-sensitive adhesive label sheet provided with a heat-sensitive pressure-sensitive adhesive composition layer comprising a thermoplastic resin, a tackifier, and a solid plasticizer containing a dispersant on one side of a support. By using a polyvinyl alcohol-based resin having a weight average molecular weight of 11000 to 39000 as a dispersant for the solid plasticizer in the heat-sensitive adhesive composition layer, the heat-sensitive adhesive composition layer easily flows during heating and melting. As a result, it becomes easy to adhere to a rough adherend such as corrugated cardboard, so that the adhesive force does not decrease even after being attached, and it is possible to exhibit good adhesive force.
The thermoplastic resin used in the heat-sensitive adhesive composition layer mainly composed of the thermoplastic resin, the tackifier and the solid plasticizer in the present invention is a natural rubber latex obtained by graft copolymerization with a vinyl monomer, and an acrylic ester copolymer. Polymer, methacrylic ester copolymer, acrylic ester-methacrylic ester copolymer, acrylic ester-styrene copolymer, acrylic ester-methacrylic ester-styrene copolymer, ethylene-vinyl acetate copolymer It is preferable to use at least one compound selected from the group consisting of: Moreover, it is preferable that the glass transition temperature of a thermoplastic resin is -65 degreeC or more and -5 degrees C or less. When the glass transition temperature is higher than −5 ° C., the tackiness is lowered, and when it is lower than −65 ° C., the blocking resistance is lowered.

The application amount of the heat-sensitive adhesive composition 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 coating amount of the heat-sensitive adhesive composition 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 economically preferable.
The content of the thermoplastic resin in the heat-sensitive adhesive composition 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 which is solid at room temperature and melts upon heating is used, and its melting point is preferably 70 ° C. or higher, more preferably 80 ° C. or higher, and its upper limit is about 200 ° C. When the melting point is less than 70 ° C., when the thermosensitive adhesive composition is used, there are problems in storage (blocking) such that adhesive force is exhibited at a normal storage environment temperature.
In addition, there may be a problem in production such that an adhesive force is developed when the coating liquid of the heat-sensitive adhesive composition 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.

The content of the solid plasticizer in the heat-sensitive adhesive composition 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, storage problems such as adhesive force appearing under normal storage environment temperature (blocking) occur, and when it exceeds 80% by weight, May come down.
Specific examples of the solid plasticizer used in the heat-sensitive adhesive composition layer of the present invention include dicyclohexyl phthalate (melting point: 65 ° C.), diphenyl phthalate (melting point: 73 ° C.), N-cyclohexyl-p-toluenesulfonamide. (Melting point 86 ° C.), sucrose benzoate (melting point 98 ° C.), ethylene glycol dibenzoate (melting point 70 ° C.), trimethylolethane tribenzoate (melting point 73 ° C.), pentaerythritol tetrabenzoate (melting point 95 ° C.), Sucrose octaacetate (melting point 89 ° C.), catechol dibenzoate (melting point 86 ° C.) and the like, and further triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate] (melting point 77 ° C), 1,6-hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate Hindered phenol compounds such as (melting point 103 ° C.), 2- [5 ′-(1 ″, 1 ″, 3 ″, 3 ″ -tetramethylbutyl) -2′-hydroxyphenyl] benzotriazole (melting point 103 ° C.) 2- [3 ′, 5′-di- (2 ″, 2 ″ -dimethylpropyl) -2′-hydroxyphenyl] benzotriazole (melting point 80 ° C.), 2- (3′-t-butyl-5′- Methyl-2′-hydroxyphenyl) -5-chlorobenzotriazole (melting point 138 ° C.), 2- (3,5-di-t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole (melting point 155 ° C.), 2- (5-methyl-2-hydroxyphenyl) benzotriazole (melting point 130 ° C.), 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole (melting point 80 ° C. Triazole compounds such like.
Among these compounds, it is preferable to use a hindered phenol compound and a triazole compound from the viewpoint of a long duration of adhesiveness after heating, and adhesion stability over time, and after melting the heat-sensitive adhesive composition layer A plurality of them may be used in combination in order to maintain the amorphization of the resin and to further increase the adhesive duration.
These solid plasticizers and compounds are atomized by a wet or dry pulverizer such as a ball mill, a sand mill, a paint shaker, a dyno mill, an attritor, and a Henchel mixer, and used as an aqueous dispersion. It is also possible to encapsulate and use. The particle size of the solid plasticizer is preferably 10 μm or less, more preferably 5 μm or less, but from a practical point of view it is 0.7 to 2 μm.

  In the heat-sensitive adhesive composition 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 is used in addition to the thermoplastic resin and the solid plasticizer. be able to. 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 or di (p-oxalate) 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 polyvinyl alcohol resin is used as a dispersant for the solid plasticizer, which is an essential component of the present invention. As the polyvinyl alcohol-based resin, in addition to a saponified product of polyvinyl acetate produced by a known method, a monomer that can be copolymerized with other vinyl acetates may be contained. As, olefins such as ethylene, propylene, isobutylene, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, or salts thereof, nitriles such as acrylonitrile, methacrylonitrile, Examples thereof include amides such as acrylamide and methacrylamide, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, and salts thereof. Further, it may be modified with methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate or the like. Preferred is a copolymer of olefin sulfonic acid or a salt thereof, and since the compatibility between the solid plasticizer and the thermoplastic resin is good, the adhesive property at the time of hot melting is improved.
Moreover, the weight average molecular weight of the said polyvinyl alcohol-type resin used by this invention shall be 11000-39000. When it is less than 11000, the binding force of the heat-sensitive adhesive composition layer becomes weak, and the blocking property is greatly reduced. On the other hand, if it exceeds 39000, although the blocking property is excellent, the adhesive strength to a rough surface adherend such as corrugated cardboard is reduced, and particularly the adhesive strength is suddenly lost in storage after pasting.
Moreover, the addition amount of a dispersing agent shall be 2-10 weight part with respect to 100 weight part of solid plasticizers. If it is less than 2 parts by weight, the solid plasticizer is poorly dispersed, which causes a trouble in the production process. On the other hand, when more than 10 weight part is added, the fall of adhesive force is caused.
Further, the saponification ratio of the polyvinyl alcohol-based resin is 70% or more. If it is less than 70%, its water solubility tends to decrease, so that it becomes difficult to disperse the solid plasticizer, and troubles are likely to occur in the dispersion step.
Here, the “saponification rate” indicates the percentage of hydroxyl groups that can be hydroxylated in the vinyl acetate polymer or copolymer, and the acetic acid present in the vinyl acetate polymer or copolymer. When all the groups are hydroxyl groups, the “saponification rate” is 100%.

Furthermore, in order to improve the adhesive force of the heat-sensitive adhesive composition layer, a tackifier may be added to the heat-sensitive adhesive composition layer.
Examples of such tackifiers include various commonly used compounds. For example, rosin derivatives (rosin, polymerized rosin, hydrogenated rosin) that are tackifiers or terpene resins (terpene resins, aromatic modified terpene resins) Terpene phenol resin, hydrogenated terpene resin), petroleum resin, phenol resin and xylene resin may be used.
In the heat-sensitive adhesive composition 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 composition layer of the present invention and the support is a (meth) acrylate copolymer, styrene-isoprene copolymer, styrene-acrylate ester. Copolymer, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, vinyl acetate-acrylate copolymer, ethylene-acrylate copolymer, vinyl acetate-ethylene-acrylate copolymer, etc. Resin. 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. .

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, leuco dyes generally known in this type of leuco recording material are applied, and triphenylmethane, fluoran, phenothiazine, auramine, spiropyran, An indinophthalide system or the like can be used. Specific examples of the leuco dye include 3,3-bis (p-dimethylaminophenyl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3 , 3-bis (p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-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- ( -P-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) xanthyl} benzoate lactam, 3-diethylamino-6-methyl-7- (m-trichloromethyl) Anilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-N-methyl-N-amylamino-6-methyl-7-anilino Fluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino 6-Methyl-7-anilinofluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluorane, benzoylleucomethylene blue, 6'-chloro-8'- Methoxybenzoindolinopyrrhispirane, 6'-bromo-3'-methoxybenzoindolinopyrirospirane, 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'-dimethyla) Nilino) fluorane, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3-morpholino-7- (N- Propyltrifluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7- (N-benzyltrifluoromethylanilino) fluorane, 3-pyrrolidino-7 -(Di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-toluidino) -7- (α-phenyl) Ethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane, 2-chloro-3- (N-methyltoluidino) -7- (pn- Butylanilino) fluorane, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesidino-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-dimethylaminopheny E) 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) benzophthalide, 3-dimethylamino-6-dimethyl Ruaminofluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3,3-bis {2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl} -4,5 , 6,7-tetrachlorophthalide, 3,3-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-anilinofur Orane, 3,6-bis (dimethylamino) fluorane spiro (9,3 ')-6'-dimethylaminophthalide, 3-diethylamino-6-chloro-7-anilinofluorane, -{N-ethyl-N- (2-ethoxypropyl) amino} -6-methyl-7-anilinofluorane, 3- {N-ethyl-N-tetrahydrofurfurylamino} -6-methyl-7-ani Linofluorane, 3-diethylamino-6-methyl-7-mesidino-4 ', 5'-benzofluorane, 3- (N-methyl-N-isobutylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane and the like can be mentioned.

As the developer, electron-accepting compounds such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof can be used.
Specific examples of the developer include 4,4'-isopropylidenebisphenol, 3,4'-isopropylidenebisphenol, 4,4'-isopropylidenebis (o-methylphenol), 4,4'-s-butyl Ridenbisphenol, 4,4'-isopropylidenebis (ot-butylphenol), 4,4'-cyclohexylidenediphenol, 4,4'-isopropylidenebis (2-chlorophenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'-butylidenebis (6-t-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-chlorosalicylanilide, salicyl-o-chloroanilide, 2-hydroxy-3-naphthoic acid, antipyrine complex of zinc thiocyanate, zinc salt of 2-acetyloxy-3-naphthoic acid 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, zinc salts of hydroxynaphthoic acid, metal salts such as aluminum salts, calcium salts, methyl bis (4-hydroxyphenyl) acetate, bis (4- Hydroxyphenyl) benzyl acetate, 4- {β- (p-methoxyphenoxy) ethoxy} salicylic acid, , 3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 2,4'-diphenolsulfone, 3,3'-diallyl-4,4'-diphenol Sulfone, α, α-bis (4-hydroxyphenyl) -α-methyltoluene, tetrabromobisphenol A, tetrabromobisphenol S, 4,4′-thiobis (2-methylphenol), 3,4-dihydroxy-4 ′ -Methyldiphenyl sulfone, 4,4'-thiobis (2-chlorophenol) and the like.

  In the present invention, various conventional binder resins can be used to form the heat-sensitive recording layer. Examples of the binder resin include polyvinyl alcohol; starch and derivatives thereof; cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose; sodium polyacrylate, polyvinylpyrrolidone, acrylamide-acrylate copolymer, acrylamide Water-soluble polymers such as acrylic ester-methacrylic acid copolymer, metal salt of styrene-maleic anhydride copolymer, metal salt of isobutylene-maleic anhydride copolymer, polyacrylamide, sodium alginate, gelatin, casein; Polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic ester, polymethacrylic ester, polybutyl methacrylate, vinyl chloride-vinyl acetate copolymer Ethylene - vinyl acetate copolymer, styrene - butadiene copolymer, styrene - butadiene - include resins such as an 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; fatty acid amides such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate. Metal salts; p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, 1-hydroxy-2 -Methyl naphthoate, diphenyl carbonate, dibenzyl terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-bis (phenoxy) ethane, 1,2-bi Sus (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-propargyloxy Biphenyl, dibenzoyloxymethane, 1,3-dibenzoyloxypropane, dibenzyl disulfide, 1,1-diphenylethanol 1,1-diphenylpropanol, p- (benzyloxy) benzyl alcohol, 1,3-diphenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, dibenzyl oxalate, 1,5 -Bis (p-methoxyphenyloxy) -3-oxapentane and the like.
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.
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.

In the present invention, the first main surface and the second main surface of the support indicate the top and bottom (front and back) of the support, the first main surface indicates the surface on which the heat-sensitive adhesive composition layer is provided, and the second main surface A surface refers to a surface on which a heat-sensitive recording layer is provided.
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. Examples of the paper strength enhancer include polyamide-polyamine-epichlorohydrin, urea-formaldehyde resin, melamine-formaldehyde resin, polyethyleneimine, polyacrylamide, various modified starches, plant gum, and CMC.
As the support according to the present invention, general paper such as glassine paper, art paper, coated paper, cast paper can be used, and fillers, sizing agents, paper strength enhancers, dyes, and other raw materials usually used in papermaking. Can be used as needed.
Plastic sheets such as polyethylene, polypropylene, polyethylene terephthalate, polyamide, etc., and synthetic paper or nonwoven fabric made of these synthetic fibers, or laminated paper obtained by laminating synthetic resin on one side or both sides of paper, 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 a heat-sensitive recording layer, an intermediate layer, a protective layer and a heat-sensitive adhesive layer of the heat-sensitive recording material of the present invention, a blade coater, a gravure coater, a gravure offset coater, a bar coater, ordinarily 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.
In addition, a pre-printed layer can be provided on the opposite side (surface) of the heat-sensitive adhesive composition layer of the heat-sensitive recording material, and eye mark printing as a sensing means is provided on the surface or the heat-sensitive adhesive layer surface. You can also. Both printing methods include general printing methods such as UV printing, EB printing, and flexographic printing.
Furthermore, the heat-sensitive adhesive label sheet produced using the heat-sensitive adhesive composition according to the present invention may be wound around a known core material in a roll shape, and becomes a roll shape without using the core material. It may be.

According to the present invention, it is possible to provide a heat-sensitive adhesive composition that is free from defects in the dispersion step, has excellent adhesion to rough surface adherends such as cardboard, and is excellent in blocking properties.
Moreover, the heat sensitive adhesive label sheet produced using this heat sensitive adhesive composition was able to contribute to the label field | area and environmental conservation.

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

Example 1
(1) Preparation of Dye Dispersion Solution A composition consisting of 20 parts of 3-dibutylamino-6-methyl-N-7-anilinofluorane, 20 parts of a 10% aqueous solution of PVA, and 60 parts of water was used to obtain an average particle size of Dispersed to 0.5 μm.
(2) Preparation of color developer dispersion 4-isopropoxy-4'-hydroxydiphenylsulfone 20 parts, di- (p-methylbenzyl) oxalate 10 parts, calcium carbonate 10 parts, PVA 10% aqueous solution 30 parts, water A composition consisting of 30 parts was dispersed with a ball mill until the average particle size became 0.5 μm.
(3) Preparation of thermal recording layer coating solution 20 parts of dye dispersion, 60 parts of developer dispersion, 30 parts of 10% aqueous solution of PVA (KL-318, manufactured by Kuraray), dioctylsulfosuccinic acid aqueous solution (5% solid content) ) A composition comprising 1 part was mixed to prepare a thermosensitive recording 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 rate 98%, manufactured by Shin-Etsu Chemical Co., Ltd.) 10% aqueous solution, adipic acid hydrazide (crosslinking agent) aqueous solution (solid content 10%) 10 A protective layer coating solution was prepared by mixing a composition consisting of 43 parts of water and 43 parts of water.
(5) Application of heat-sensitive recording layer and protective layer A heat-sensitive recording 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 heat-sensitive recording 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 of 2- (3′-t-butyl-5′-methyl-2′-hydroxyphenyl) -5-chlorobenzotriazole, sulfonic acid-modified polyvinyl alcohol as a dispersant 25 parts of 10% aqueous solution (manufactured by Nippon Synthetic Chemical Co., Ltd .: L-3266, weight average molecular weight 15000, saponification rate 88%), 0.5 parts of surfactant Newcol-290M (manufactured by Nippon Emulsifier), and 200 parts of water uniformly And dispersed to a mean particle size of 1.0 μm using a ball mill to obtain a solid plasticizer dispersion.
In the dispersion process, the state of the dispersion liquid was visually confirmed, and the stability of the dispersion liquid after dispersion was further confirmed with a homomixer (10000 rpm, 5 minutes) manufactured by Tokushu Kika Kogyo.
(7) Preparation of thermosensitive adhesive liquid 100 parts of thermoplastic resin emulsion AP5570 (acrylic acid-2-ethylhexyl resin main component, Showa High Polymer, solid content 55%, Tg-65 ° C.), E100 (terpene as tackifier) Phenol main component, manufactured by Arakawa Chemical Co., Ltd., solid content 50%, softening point 145 ° C.) was mixed sufficiently at a ratio of 70 parts, the above-mentioned solid plasticizer dispersion liquid was 540 parts, and water was 130 parts to prepare a heat-sensitive adhesive liquid.
(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
The same procedure as in Example 1 was performed except that polyvinyl alcohol (manufactured by Nippon Gosei Kagaku: GL-05, weight average molecular weight 11000, saponification rate 88%) was used as the dispersant for the solid plasticizer in Example 1 (6). A heat-sensitive recording material of the invention was obtained.

Example 3
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that polyvinyl alcohol (weight average molecular weight 39000, saponification rate 88%) was used as the dispersant of (6) the solid plasticizer in Example 1.

Example 4
Example 2 is the same as Example 2 except that the dispersant of (6) solid plasticizer in Example 1 was changed to acetoacetyl-modified polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Z-100, weight average molecular weight 29000, saponification rate 99%). Similarly, the heat-sensitive recording material of the present invention was obtained.

Example 5
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the aqueous solution of the dispersant of (6) solid plasticizer in Example 1 was 100 parts.

Example 6
Except for the point that (7) thermoplastic resin emulsion of Example 1 was a copolymer emulsion of 2-ethylhexyl acrylate / methyl acrylate / styrene (made by Showa Polymer: solid content concentration 55.4%, Tg-5 ° C.). Obtained the heat-sensitive recording material of the present invention in the same manner as in Example 1.

Example 7
(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), 1.6 parts surfactant Dapro W-77 (made by Elementis Japan) and 74.4 parts water were stirred and dispersed to prepare a hollow filler dispersion.
(10) Preparation of under liquid 36 parts of thermoplastic resin emulsion AP5570 (acrylic acid-2-ethylhexyl resin main component, Showa Polymer, solid content 65%, Tg-65 ° C.) and 160 parts of hollow filler dispersion were stirred. The under liquid was prepared.
Between the support of Example 1 and the heat-sensitive adhesive layer, the above under liquid was applied and dried as an under layer so that the dry adhesion amount was 4 g / m ² . A heat-sensitive recording material was obtained.

Example 8
Between the support of Example 2 and the heat-sensitive adhesive layer, the under liquid was applied as an under layer so that the dry adhesion amount was 4 g / m ² and dried, except that the under liquid was applied and dried. A heat-sensitive recording material was obtained.

Example 9
The heat-sensitive material of the present invention was the same as Example 1 except that polyvinyl alcohol (manufactured by Kuraray: PVA-103, weight average molecular weight 15000, saponification rate 99%) was used as the dispersant for the solid plasticizer in Example 1 (6). A recording material was obtained.

Example 10
The heat-sensitive material of the present invention was the same as Example 7 except that polyvinyl alcohol (manufactured by Kuraray: PVA-205, weight average molecular weight 27000, saponification rate 88%) was used as the dispersant for the solid plasticizer in Example 1 (6). A recording material was obtained.

Example 11
This example is the same as Example 7 except that (7) the thermoplastic resin emulsion of Example 1 is an ethylene vinyl acetate copolymer emulsion (manufactured by Sumitomo Chemical: FREX751, solid content 50 wt%, Tg-15 ° C.). A heat-sensitive recording material of the invention was obtained.

Example 12
Example 7 and Example 7 except that the solid plasticizer in Example 1 was changed to 4,4′-thiobis- (6-tert-butyl-3-methylphenol) (Ouchi Shinsei Chemical Industry: Nocrack 300). Similarly, the heat-sensitive recording material of the present invention was obtained.

Example 13
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 7 except that (6) the solid plasticizer of Example 1 was tris (pt-butoxyphenyl) phosphine (made by Hokuko Chemical Co., Ltd .: TTBPP). .

Example 14
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 7 except that (720) the tackifier in Example 1 was changed to E720 (special rosin ester main component, manufactured by Arakawa Chemical Co., Ltd., softening point 100 ° C.).

Example 15
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 7 except that LP-325 (terpenephenol main component, Harima Chemicals, softening point 130 ° C.) was used as the tackifier in Example 1 (7). .

Comparative Example 1
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that polyvinyl alcohol (weight average molecular weight 8000, saponification rate 88%) was used as the dispersant of (6) the solid plasticizer in Example 1.

Comparative Example 2
Comparison was made in the same manner as in Example 1 except that the dispersant of (6) the solid plasticizer in Example 1 was changed to itaconic acid-modified polyvinyl alcohol (Kuraray: KL-318, weight average molecular weight 80000, saponification rate 88%). An example thermal recording material was obtained.

Comparative Example 3
Heat sensitive in the same manner as in Example 7 except that the dispersant of (6) solid plasticizer in Example 1 was itaconic acid-modified polyvinyl alcohol (Kuraray: KL-318, weight average molecular weight 80000, saponification rate 88%). A recording material was obtained.

<Adhesive strength>
About the heat-sensitive recording materials produced in this example and the comparative example, after production, those stored for 1 day in a standard state (23 ° C. and 65%) and those stored for 7 days in a 40 ° C. Dry environment are 4 cm wide and 10 cm long. Platen roll 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 Was activated by bringing the heat-sensitive adhesive layer surface into contact with the thermal head under the condition of a pressure of 6 kgf / line.
Subsequently, it was affixed to the corrugated cardboard in the longitudinal direction with a 2 kg pressure rubber roller, and after 2 minutes, it was peeled off 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, the data was read and averaged at intervals of 0.1 seconds, and the values were evaluated and evaluated according to the ranks shown in Table 1 below. This test was carried out under standard conditions (23 ° C. and 65%).
<Blocking property>
The protective layer surface of the heat-sensitive recording layer and the heat-sensitive adhesive composition layer surface of the same sample were brought into contact, tested at 200 g / cm ² at 50 ° C. under dry conditions for 24 hours, left at room temperature, and then peeled off the sample. The blocking property was evaluated in the rank as shown in Table 2 below. In addition, it refers to the state in which the degree of blocking becomes heavy in the order of "Hook", "Peeling sound", "Spot transfer", and "Hagare". "Hook" sticks lightly even when it is not sticky. In this case, “self-weight” refers to a state where two pieces are stacked and only the upper paper is held, so that it will peel off naturally. In addition, “peeling sound” means that a sound is produced when an attempt is made to peel from a sticky state, and “spot transfer” refers to a state in which the heat-sensitive adhesive layer is transferred to the back surface in the form of dots. “Peeling” refers to a phenomenon in which the heat-sensitive adhesive layer sticks to the back surface and the heat-sensitive adhesive layer peels off or the paper on the back surface peels (breaks).
Table 3 shows the measurement results and evaluation results of Examples 1 to 15 and Comparative Examples 1 to 3 for the dispersibility of the solid plasticizer, the adhesiveness to cardboard, and the blocking property.

From the results of Table 3, the heat-sensitive adhesive compositions of the present invention of Examples 1 to 15 and the heat-sensitive adhesive label sheet using the same have better dispersibility of the solid plasticizer than Comparative Example 1, and Compared with Comparative Examples 1 to 3, the adhesive strength over time is not reduced even after being bonded to the corrugated cardboard while maintaining the blocking property.

Claims (8)

A thermosensitive adhesive composition comprising a thermoplastic resin, a tackifier, and a solid plasticizer containing a dispersant, wherein the dispersant is a polyvinyl alcohol having a weight average molecular weight of 11000 to 39000 and a saponification rate of 70% or more . system resin der is, the heat-sensitive adhesive composition characterized in that it contains 2 to 10 parts by weight of said dispersing agent to said solid plasticizer 100 parts by weight. 2. The thermosensitive adhesive composition according to claim 1, wherein a glass transition point of the thermoplastic resin is −65 ° 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 containing 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. Wherein on the second major surface of the support, the heat-sensitive adhesive label sheet according to claim 3 or 4, characterized in that it has an ink image developed by the UV ink. The heat-sensitive adhesive label sheet according to any one of claims 3 to 6 , wherein the heat-sensitive adhesive label sheet is wound in a roll shape. The heat-sensitive adhesive label sheet according to claim 7, wherein the heat-sensitive adhesive label sheet is wound around the core material in a roll shape.