JP2009122648A - Heat-sensitive label and container with label - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sensitive label having excellent blocking resistance, workability and sticking stability with a delayed effect, sufficient adhesion strength to a label base and a container as an adherent after stuck, and easily peelable by a hand after used, without leaving glue on the container and is easily removed from the container, and to provide a container with a label to which the above label is stuck. <P>SOLUTION: The heat-sensitive label has an adhesive layer on a label base, wherein the adhesive layer is formed of an emulsion type heat-sensitive adhesive containing an ethylene-vinyl acetate resin (A), a synthetic rubber (B) and a solid plasticizer (C) with a mixing ratio [(A)/(B)] of (A) to (B) ranging from 20/80 to 80/20 and a mixing ratio [ä(A)+(B)}/(C)] of the sum [(A)+(B)] of (A) and (B) to (C), which ranges from 27/75 to 65/35. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat-sensitive label that is not sticky at room temperature and develops stickiness by heating, and a labeled container equipped with the heat-sensitive label, more specifically, an adhesive layer is formed from a delayed heat-sensitive adhesive. Related to thermal labels.

  In recent years, when selling water, soft drinks, etc., plastic containers such as polyethylene terephthalate (PET) bottles are widely used, and these containers include product names, designs, explanations about contents, etc. A printed label is often attached. As such a label, for example, a heat-sensitive label of a type in which a label coated with a heat-sensitive adhesive (heat-sensitive adhesive) is wound around and attached to the entire surface or both ends is used.

  Such a heat-sensitive label can develop adhesiveness by heating the adhesive layer (glue) part at the time of sticking, so it does not have adhesiveness until use, without using release paper There is an advantage that it can be stored. Among the above-mentioned heat-sensitive adhesives, the delayed heat-sensitive adhesive has an advantage that it is particularly excellent in sticking stability because once it develops tackiness by heating, the tackiness persists for a certain time after the heating is stopped. Such a delayed heat-sensitive adhesive generally comprises a thermoplastic resin, a solid plasticizer, and a tackifier as constituent components.

  The heat-sensitive adhesive used for the heat-sensitive label is required to have a property of firmly adhering to a container, a label base material or the like in order to prevent troubles such as peeling of the label when the container is used. However, on the other hand, from the viewpoint of recycling, it is required that the label can be easily peeled after use of the container, and that the adhesive does not remain on the container side at the time of peeling (so-called “glue residue” does not occur). That is, thermosensitive adhesives are required to have conflicting characteristics such as high adhesiveness, easy peelability, and suppression of adhesive residue. In addition, from the viewpoint of recycling, the label is also required to be easily peeled off from the container by an aqueous alkaline solution or hot water.

  As a label for containers that achieves both adhesiveness and easy peelability, the label is bonded directly to the bottle and the other end is bonded to one end of the label (label surface). There is known a container label using a pressure-sensitive adhesive that hardly adheres to one end, and a pressure-sensitive adhesive having an excellent adhesive force at the other end that adheres to the label surface (see Patent Document 1). However, in this case, since it is necessary to use two types of pressure-sensitive adhesives, there are problems in cost and productivity.

  As described above, the present situation is that a heat-sensitive adhesive having high adhesiveness, easy peelability, and adhesive residue deterrence, easy to handle, and high in productivity is not yet known.

JP 2004-219621 A

  The object of the present invention is excellent in blocking resistance, excellent in workability and sticking stability due to delay (delay tack), and has sufficient adhesive force on the label substrate and the container as an adherend after sticking. To provide a heat-sensitive label that can be easily removed by hand after use, does not cause adhesive residue in the container, and can easily remove the label from the container, and a labeled container equipped with the label It is in.

  As a result of intensive studies to solve the above problems, the present inventors have achieved excellent adhesiveness, blocking resistance, by using an emulsion-type heat-sensitive adhesive composed of a combination of a resin with a specific formulation and a solid plasticizer, The inventors have found that a heat-sensitive label that achieves easy peeling and suppression of adhesive residue at the time of peeling, and is excellent in workability due to the delay property, has completed the present invention.

  That is, the present invention is a thermosensitive label in which an adhesive layer is laminated on a label base material, and the adhesive layer comprises an ethylene-vinyl acetate resin (A), a synthetic rubber (B), and a solid plasticizer (C ), The mixing ratio [(A) / (B)] (weight ratio in terms of solid content) of the ethylene-vinyl acetate resin (A) and the synthetic rubber (B) is 20/80 to 80/20, ethylene- Mixing ratio [{(A) + (B)} / (C) of total amount [(A) + (B)] of vinyl acetate resin (A) and synthetic rubber (B) and solid plasticizer (C) ] (The weight ratio in terms of solid content) is formed from an emulsion-type heat-sensitive adhesive having a weight ratio of 25/75 to 65/35.

  Furthermore, the present invention is a heat-sensitive label in which an adhesive layer is laminated on a label substrate, and the adhesive layer comprises an ethylene-vinyl acetate resin (A), a synthetic rubber (B), and a solid plasticizer (C ), And the mixing ratio [(A) / (B)] (weight ratio in terms of solid content) of the ethylene-vinyl acetate resin (A) and the synthetic rubber (B) is 60/40 to 80/20, ethylene- Mixing ratio [{(A) + (B)} / (C) of total amount [(A) + (B)] of vinyl acetate resin (A) and synthetic rubber (B) and solid plasticizer (C) The heat-sensitive label is formed from an emulsion-type heat-sensitive adhesive having a weight ratio in terms of solid content of 65/35 to 75/25.

  Furthermore, the present invention provides a labeled container in which the above-mentioned thermosensitive label whose label base material is composed of a polyester resin or polyolefin resin is attached to a container composed of a polyester resin or polyolefin resin. .

  Furthermore, the present invention provides the labeled container, wherein the label base is composed of a polyolefin resin and the container is composed of a polyester resin.

  Furthermore, the present invention provides the above-mentioned label in which one end of a label is affixed to a container, the label is wound around the container, and the other end is overlapped and adhered to the surface of the label substrate on the one end. Provide the attached container.

  The thermosensitive label of the present invention is excellent in workability and sticking stability because of its excellent blocking resistance and delay. Moreover, after sticking, it has sufficient adhesive force with respect to the container which is a label base material and a to-be-adhered body, and the trouble which a label peels in a distribution process etc. does not arise. Furthermore, after use, it can be easily peeled by hand, and no adhesive residue is produced on the container, so that it is excellent in recyclability. Therefore, it is particularly useful as a heat-sensitive label used for PET bottles and the like.

  The heat-sensitive label of the present invention has a layer structure in which at least one adhesive layer is laminated on a label substrate.

  The adhesive layer used in the heat-sensitive label of the present invention comprises an ethylene-vinyl acetate resin (A) (hereinafter sometimes referred to as “component (A)”) and a synthetic rubber (B) (hereinafter referred to as “component (B ) ”And a solid plasticizer (C) (hereinafter sometimes referred to as“ component (C) ”) as an essential component. In the present specification, “emulsion-type heat-sensitive adhesive” may be simply referred to as “heat-sensitive adhesive”. The heat-sensitive adhesive is an adhesive that has a delay property that is activated by heat to exhibit tack and has a stickiness for a certain period. The adhesive having the above characteristics has almost no tack at normal temperature until it is activated by heating, and therefore does not require a release paper, and is excellent in environmental suitability and handleability. Further, since the adhesiveness is maintained for a long time even after heat release after heating, it is easy to handle in the label mounting process and the like, which is advantageous in terms of improving workability and productivity. In the case of an adhesive that does not have a delay property, such as a hot melt type, the adhesiveness is lost when heat is dissipated, so it is necessary to attach the label immediately after heating, making manufacturing difficult and reducing workability and productivity. There is a case.

  The ethylene-vinyl acetate resin (A) (component (A)) in the present invention is a resin (copolymer) containing ethylene and vinyl acetate as essential monomer components. In addition, as a monomer component of a component (A), if it is in the range which does not prevent the effect of this invention, you may use copolymerization components other than the said ethylene and vinyl acetate. Examples of the copolymer component include vinyl monomers such as vinyl chloride; (meth) acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, and 5-norbornene-2,3-dicarboxylic acid. Unsaturated carboxylic acid; unsaturated carboxylic anhydride such as maleic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, tetrahydrophthalic anhydride; methyl (meth) acrylate, (meth) acrylic acid Ethyl, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic acid Unsaturated carboxylic acid esters such as glycidyl, monoethyl maleate, diethyl maleate Acrylamide, methacrylamide, unsaturated amides or imides, such as maleimide; (meth) sodium acrylate, and the like unsaturated carboxylic acid salt such as zinc (meth) acrylate. These copolymerization components can be used alone or in combination of two or more.

  The ethylene content in the ethylene-vinyl acetate resin (A) is not particularly limited, but is preferably 1 to 50% by weight, more preferably 3 to 40% by weight, further based on the total weight of the component (A). Preferably it is 5-35 weight%. The vinyl acetate content is preferably 99 to 50% by weight, more preferably 97 to 60% by weight. When the ethylene content in the component (A) exceeds 50% by weight, when the vinyl acetate content is less than 50% by weight, the adhesion with the polyester resin may be deteriorated, and the ethylene-vinyl acetate resin ( Since the glass transition temperature (Tg) of A) becomes low and blocking tends to occur, it is not preferable. On the other hand, when the ethylene content is less than 1% by weight, when the vinyl acetate content exceeds 99% by weight, the adhesive strength to the polyolefin-based resin decreases, which is not preferable.

  The glass transition temperature (Tg) of the ethylene-vinyl acetate resin (A) is not particularly limited, but is preferably −40 ° C. to 30 ° C. The Tg can generally be controlled by the copolymer composition of ethylene and vinyl acetate, the molecular weight, and the like.

  The minimum film-forming temperature (MFT) (which can be measured according to ASTM D 2354) in the emulsion state of the ethylene-vinyl acetate resin (A) is not particularly limited, but is from −20 ° C. It is preferable to use one at 30 ° C. In the case where the MFT satisfies the above range, it is preferable because the cohesive force is good under the use temperature condition of the adhesive of the present invention. When MFT exceeds 30 degreeC, the film forming of an adhesive bond layer becomes inadequate and it is inferior to adhesiveness and a drying property, and is unpreferable.

  In the present invention, the ethylene-vinyl acetate resin (A) is used as an aqueous dispersion (emulsion), but the viscosity of the aqueous dispersion is not particularly limited, but from the viewpoint of printability, it is 10 to 5000 mPa · s. s is preferred.

  The ethylene-vinyl acetate resin (A) can be obtained by a known and usual polymerization method, but a commercially available product can also be used. Examples of such commercially available products include “Sumikaflex” manufactured by Sumitomo Chemical Co., Ltd. and “Denka EVA Tex” manufactured by Denki Kagaku Kogyo Co., Ltd.

  As the synthetic rubber (B) (component (B)) in the present invention, a publicly known and commonly used synthetic rubber can be used. For example, butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber ( NBR), butadiene rubber such as acrylate-butadiene rubber (ABR), olefin rubber such as ethylene propylene (diene) rubber (EPM, EPDM), urethane rubber, and silicone rubber. Of these, butadiene rubbers such as styrene-butadiene rubber and methyl methacrylate-butadiene copolymer are preferable, and styrene-butadiene rubber (styrene-butadiene copolymer elastomer) is most preferable.

  Further, the synthetic rubber (B), in particular, a butadiene rubber such as styrene-butadiene rubber may be a modified product having a reactive functional group introduced therein. The reactive functional group is, for example, a functional group that reacts with or interacts with an ester bond portion of polyester (such as a hydrogen bond), and is not particularly limited. For example, a carboxyl group (including a carboxylic acid anhydride), a hydroxyl group , Isocyanate groups, epoxy groups and the like. Among these, from the viewpoint of improving the interlayer strength between the label base material and the adhesive layer, a dicarboxylic anhydride group (modified with dicarboxylic anhydride) is preferable, and a maleic anhydride group (modified with maleic anhydride) is particularly preferable. The term “modified” includes both “reactive functional groups introduced into the polymer main chain by grafting” and “introduced by copolymerization”.

  Although the glass transition temperature (Tg) of the said synthetic rubber (B) is not specifically limited, -50-40 degreeC is preferable from a viewpoint of adhesive force and blocking resistance, More preferably, it is -40-30 degreeC.

  As the synthetic rubber (B), for example, commercial products such as Nippon A & L Co., Ltd. “Nalstar SR Series” (styrene-butadiene rubber), “Siatex NA series” (acrylonitrile-butadiene rubber) can be used. .

  The solid plasticizer (C) (component (C)) in the present invention is non-tacky at room temperature, but melts by heating, adjusts the solidification rate of the adhesive, and imparts delay properties. It has the role of plasticizing a resin composition comprising A) and component (B) to develop and maintain adhesiveness. As such a solid plasticizer (C), a known solid plasticizer can be used. Diphenyl phthalate, dihexyl phthalate, dicyclohexyl phthalate (DCHP: melting point 66 ° C.), dihydroabiethyl phthalate, Phthalic acid ester compounds such as dimethyl isophthalate; benzoic acid such as trimethylolethane tribenzoate, trimethylolpropane tribenzoate (melting point 88 ° C.), glyceride tribenzoate (melting point 73 ° C.), pentaerythritol tetrabenzoate Ester compound; sucrose octaacetate, tricyclohexyl ketenoate, triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate)] (melting point 77 ° C.), 1,6-hexane Diol bis [3- (2,5-di-t-butyl-4-hydroxyphene ) Propionate] (melting point: 103 ° C.) and other fatty acid ester compounds; N-cyclohexyl-p-toluenesulfonic acid amide and other sulfonic acid ester compounds; Phosphate ester compounds, hindered phenol compounds, triazole compounds , Hydroquinone compounds and the like. Of these, DCHP and tribenzoic acid glyceride are preferably used.

  Although melting | fusing point of the said solid plasticizer (C) is not specifically limited, 50-120 degreeC is preferable, More preferably, it is 55-110 degreeC, More preferably, it is 60-105 degreeC. If the melting point is less than 50 ° C., blocking may easily occur. If the melting point exceeds 120 ° C., adhesiveness and delay properties will not be exhibited unless heated to a high temperature. It may be necessary.

  Although the particle size of the said solid plasticizer (C) is not specifically limited, 0.1-20 micrometers is preferable, More preferably, it is 0.2-15 micrometers, More preferably, it is 0.3-10 micrometers. If the particle size exceeds 20 μm, the thermal sensitivity may be inferior. The “particle diameter” in the present invention refers to the average particle diameter of the particles before addition.

  As the solid plasticizer (C), commercially available products such as “DCHP” manufactured by Osaka Organic Chemical Industry Co., Ltd. and “UNIPLEX 260” manufactured by UNITEX CHEMICAL CORPORATION can be used.

  The heat-sensitive adhesive in the present invention contains component (A), component (B), and component (C) as essential components. In the heat-sensitive adhesive, the ethylene-vinyl acetate resin (A) has a characteristic of imparting flexibility and cohesion to the adhesive layer. On the other hand, the synthetic rubber (B) has a characteristic of dramatically improving the adhesiveness of the adhesive layer by mixing with the component (A). In addition, as described above, the solid plasticizer (C) has a characteristic of exhibiting heat sensitivity and delay properties by plasticizing the adhesive layer resin with heat. Moreover, since a component (C) is granular at normal temperature, it improves blocking resistance.

  In particular, the present invention is characterized by the combined use of the three components (A) to (C). When the heat-sensitive adhesive consists of only two components (A) and (C) [when component (B) is not included] or when it consists of only two components (B) and (C) [component (A) Is not sufficient for polyolefin-based adherends, sufficient adhesive strength when a polyolefin film is used as a label substrate or when it is attached to a polyolefin bottle. Cannot be obtained. Further, when the heat-sensitive adhesive is composed only of the components (B) and (C) [when the component (A) is not included], the cohesive force of the adhesive is insufficient, and thus the cohesive failure of the adhesive layer resin is caused. This is not preferable because it tends to occur and adhesive residue tends to be generated when peeling from the polyester-based adherend. Further, when the component (C) is not used and only the components (A) and (C) are used, there is no delay and the sticking stability is poor.

  On the other hand, when the three components (A) to (C) are used together in a specific composition, the components (A) and (C) and the components (B) and (C) are compared with the two-component system. Thus, the adhesiveness (particularly, the adhesive strength to polyolefin-based adherends) is improved. Although these detailed reasons are unknown, it is assumed that the flexibility of the component (A), the surface adhesion of the component (B) and the plasticity of the component (C) by heat influence each other. Is done.

  Furthermore, by using the three components (A) to (C) together in a specific formulation, it is possible to improve the physical properties of drying property, adhesive residue deterrence and blocking resistance in a well-balanced manner.

  In the heat-sensitive adhesive of the present invention, the mixing ratio [component (A) / component (B)] of component (A) and component (B) is 20/80 to 80/20, preferably 25/75 to 75 /. 25. In addition, the said mixing ratio is represented by the weight ratio (weight ratio of solid content conversion) of each solid content of a component (A) and a component (B). When it is out of the above range, that is, when either one of the component (A) or the component (B) is excessive, the adhesiveness (particularly, the adhesive force to the polyolefin adherend) is lowered.

  Further, in the heat-sensitive adhesive of the present invention, the total amount of the component (A) and the component (B) [component (A) + component (B)] and the mixing ratio of the component (C) [{(A) + (B )} / (C)] is 25/75 to 65/35, preferably 30/70 to 60/40, more preferably 35/65 to 55/45. In the same manner as described above, the mixing ratio is also expressed by a weight ratio (weight ratio in terms of solid content) calculated based on the solid contents of the components (A) to (C). When the mixing ratio of the component (C) is less than the above range, the heat-sensitive adhesive property of the adhesive layer is lowered or the blocking resistance is lowered. On the other hand, when the total amount of the components (A) and (B) is less than the above range, the adhesiveness to the adherend such as polyester or polyolefin is lowered, or the adhesive cohesive force is lowered and the adhesive residue is reduced. It tends to occur.

  However, when the mixing ratio of the component (A) in the adhesive layer is increased, even when the mixing ratio of the component (C) is lower than the above range, sufficient adhesiveness (particularly for polyolefin-based adherends). Adhesive strength) can be exerted and the blocking resistance can be maintained. Specifically, the mixing ratio [component (A) / component (B)] of component (A) and component (B) in the adhesive layer is 60/40 to 80/20, and the component in the adhesive layer The total amount of (A) and component (B) [component (A) + component (B)] and component (C) mixing ratio [{(A) + (B)} / (C)] is 65 / 35- This is the case of 75/25. In the same manner as described above, the mixing ratio is also expressed by a weight ratio (weight ratio in terms of solid content) calculated based on the solid contents of the components (A) to (C).

  In the heat-sensitive adhesive of the present invention, the total content of the solid components (A), (B), and (C) is not particularly limited, but is 30% by weight or more based on the total weight of the adhesive. It is preferably 35 to 80% by weight, more preferably 40 to 70% by weight. When the total content of the solids (A) to (C) is less than 30% by weight, the drying property is poor, and good adhesiveness and heat sensitivity may not be obtained. The total weight of the adhesive referred to above means a weight including a dispersion medium (such as water).

  If necessary, a tackifier may be added to the heat-sensitive adhesive in the present invention. The tackifier has an effect of improving adhesiveness, and includes, for example, rosin resins [rosins such as rosin, polymerized rosin, and hydrogenated rosin; and rosin derivatives (polyhydric alcohols such as glycerin and pentaerythritol) Rosin ester compounds esterified with rosins; rosin phenol compounds in which modified phenols such as phenol and resol type phenol resins are added to rosins, resin acid dimers, etc.], terpene resins (terpene resins, aromatic modified terpenes, etc.) Resin, hydrogenated terpene resin, terpene-phenol resin, etc.), petroleum resin (aliphatic, aromatic, alicyclic), coumarone-indene resin, styrene resin, phenol resin and the like. A tackifier can be used individually or in combination of 2 or more types. Of these, terpene resins, rosin derivatives (particularly rosin phenol compounds) and the like are preferably used.

  The tackifier is also available on the market. For example, “YS Polyster” manufactured by Yashara Chemical Co., Ltd., “Pine Crystal” manufactured by Arakawa Chemical Industries, Ltd., “Tamanol E-200NT (softening point 150 ° C.)”, Examples include “Nanolet R-1050 (softening point: 105 ° C.)” manufactured by Yashara Chemical Co., Ltd.

  The content of the tackifier is preferably 0 to 40 parts by weight, more preferably 3 to 30 parts by weight in terms of solid content, with respect to 100 parts by weight of the total amount (solid content) of (A) to (C). More preferably, it is 5 to 25 parts by weight. If the content of the tackifier is too large, adhesive residue may be generated or the adhesive strength may be reduced. If the content is too small, the effect of addition may not be obtained.

  In the present invention, an anti-blocking agent or the like may be added to the heat-sensitive adhesive. Examples of such anti-blocking agents include silicone oils; water-soluble organic compounds; inorganic particles such as calcium carbonate, clay, talc, silica, alumina, mica, alumina sol, colloidal silica; paraffin, polypropylene (PP) wax, polyethylene Particles made of organic compounds such as (PE) wax, acrylic beads, fatty acid amide, and fluorine wax can be used.

  In addition to the above, the heat-sensitive adhesive of the present invention may contain known additives such as a dispersant, a thickener, an antifoaming agent, a leveling agent, and an antifungal agent, as necessary.

  The temperature at which the heat-sensitive adhesive in the present invention exhibits adhesiveness (tackiness), that is, the activation temperature of the heat-sensitive adhesive is preferably about 50 to 120 ° C, more preferably about 60 to 110 ° C. When a heat-sensitive adhesive with an activation temperature of less than 50 ° C is used, the labels are likely to block each other when storing the labels in roll form. If the activation temperature is too high, the label base material shrinks or deforms during processing. Or a high temperature heat source may be required. If a heat-sensitive adhesive having an activation temperature in the above range is used, blocking does not occur at room temperature, and handling is easy, and attachment of the heat-sensitive label to the adherend can be facilitated. The activation temperature can be adjusted by appropriately selecting the components (A) to (C), the type and amount of the tackifier, and other additives. In the present invention, the activation temperature of the adhesive layer is a temperature that produces an adhesive strength of 0.5 N / 15 mm or more when measured according to JIS K 6854-3. The heat-sensitive adhesive generally develops tackiness when heated at a temperature higher than the activation temperature.

  The heat-sensitive adhesive in the present invention can be produced by a known method using the above-described components (components (A) to (C) and other additives). In the heat-sensitive adhesive, the constituent components (A) and (B) are usually used in the form of an aqueous emulsion in which fine particles having an average particle size (particle size) of about 1 μm or less are dispersed in a dispersion medium. The solid plasticizer (C) is used in a state where the solid content is pulverized to a particle size of about 0.1 to 20 μm and dispersed in a dispersion medium using, for example, a kneader, colloid mill, bead mill, ball mill, or attritor. It is done. As the tackifier, an aqueous dispersion or an aqueous emulsion is used. The heat-sensitive adhesive can be prepared by mixing and stirring them. The dispersion medium is not particularly limited as long as it is aqueous. For example, water; a water-soluble organic compound such as a lower alcohol having 1 to 4 carbon atoms; and a mixture thereof can be used. If necessary, a dispersant, an antifoaming agent, an anti-settling agent, a stabilizer, and the like may be added to the emulsion.

  For heat-sensitive adhesives, for example, emulsion of component (A), emulsion of component (B), emulsion of component (C), tackifier (emulsion) and other components are simultaneously put into a container such as a stirring and mixing tank. Alternatively, it can be obtained by adding them under stirring sequentially or continuously, and stirring and mixing uniformly. These components may be emulsified at the same time.

  The adhesive layer in the heat-sensitive label of the present invention is formed from the heat-sensitive adhesive. The adhesive layer is formed by applying the above heat-sensitive adhesive on at least one side of the label substrate using a coating machine such as a bar coater, a gravure coater, a flexo coater, a roll coater, a curtain coater, or a spray coater, It can be formed by coating and drying by a known coating method such as die coating. In particular, when a gravure coater (gravure printing) or a flexo coater (flexo printing) is used, an adhesive layer can be partially provided at a desired location, which is preferable.

  The thickness of the adhesive layer is not particularly limited as long as it is appropriately selected in consideration of adhesiveness, appearance, cost, etc., but the thickness after drying is preferably 1 to 30 μm, more preferably 5 to 15 μm. When the thickness of the adhesive layer is thicker than 30 μm, cohesive failure may occur and the adhesive residue tends to occur, or the drying property may decrease and the productivity at the time of applying the adhesive layer may decrease. , The adhesiveness may decrease. The thickness of the adhesive layer can be measured with a micro gauge, a three-dimensional microscope, or the like.

  The heat-sensitive label of the present invention has an adhesive layer formed from the heat-sensitive adhesive having the above-described structure, and thus has excellent adhesiveness and anti-blocking property. Can prevent adhesive residue.

  The label substrate in the heat-sensitive label of the present invention can be appropriately selected in consideration of heat resistance, handleability, printability, etc., such as plastic film, plastic sheet; coated paper and other water-resistant paper, Japanese paper, synthetic paper, etc. Paper; metal foil such as aluminum foil; non-woven fabric and composites thereof can be used. Of these, a plastic film is preferable from the viewpoint of physical properties such as strength and handleability, and a transparent plastic film is particularly preferable. The plastic film can be appropriately selected according to the required physical properties, application, cost, and the like, and is not particularly limited. For example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and poly (ethylene- Polyester resins such as 2,6-naphthalenedicarboxylate (PEN); polyolefin resins such as polyethylene and polypropylene; polystyrene resins such as styrene-butadiene copolymer; polyvinyl chloride, polyamide, aramid, polyimide, polyphenylene sulfide And a film made of a resin such as acrylic. Among these, from the viewpoints of adhesiveness with the heat-sensitive adhesive layer of the present invention, cost, handleability, strength and flexibility as a support, a polyester resin or a polyolefin resin is preferable, and a polyolefin resin is more preferable. These may be used alone or in combination of two or more, copolymerized or laminated.

  Among the above, in particular, the label base material of a label to be mounted on a container having a specific gravity of 1 or more such as a PET bottle is preferably made of a material having a specific gravity of less than 1, for example, a polyolefin resin, preferably a polypropylene resin. . In such a case, the container body (or its pulverized product) can be easily separated from the label by using the specific gravity difference after using the container with the label attached, and the label and the container body can be easily recycled. Become. At this time, it is preferable to use hot alkaline water because the label can be peeled and separated simultaneously.

  The plastic film used as the label substrate may be a single-layer film or a laminated film in which a plurality of film layers are laminated according to required physical properties, applications, and the like. In the case of a laminated film, film layers made of different resins may be laminated. For example, it may be a three-layer laminated film composed of a central layer and a surface layer portion (inner layer, outer layer), a film in which the central layer is composed of a polyolefin resin or a polystyrene resin, and a surface layer is composed of a polyester resin.

  Moreover, the plastic film used as a label base material may use any of an unstretched film (non-stretched film), a uniaxially oriented film, and a biaxially oriented film according to the required physical properties and applications. For example, a non-heat-shrinkable film such as an unstretched film or a biaxially stretched film is used as a label base material for a label that is attached or pressed by winding, and particularly a biaxially stretched polypropylene film (OPP). And PET film etc. are used. In addition, a film that has been stretched in at least one direction is used as a label base material (heat-shrinkable film) of a label having heat-shrinkability such as a shrink label.

  Although the thickness of a label base material can be suitably selected in the range which does not impair mechanical strength, the handleability of a label, etc., it is about 5-100 micrometers, for example, Preferably it is about 8-60 micrometers. When the label base material of the label stuck by winding attachment or pressurization is an unstretched film or a biaxially stretched film, it is generally about 5-60 micrometers, Preferably it is about 8-50 micrometers. In the case of a label substrate (heat-shrinkable film) for shrink labels, the thickness is generally about 20 to 100 μm, preferably about 25 to 60 μm.

  The thermal contraction rate of the label base material varies depending on the type of label and is not particularly limited. However, when the label base material is a non-heat-shrinkable film, the MD direction, TD under conditions of immersion in hot water at 90 ° C. for 5 seconds. Both directions are preferably less than 5%, more preferably less than 1%. If the heat shrinkage rate is 5% or more, the label may shrink due to heat at the time of sticking, and wrinkles or misalignment may occur. On the other hand, when the label base material is a heat-shrinkable film, it is preferable to use a heat-shrinkable film mainly stretched in the MD direction (a film that shrinks more in the MD direction than in the TD direction). As a thermal shrinkage rate, for example, the MD direction is about 10 to 60% and the TD direction is about −3 to 20% under conditions of immersion in hot water at 90 ° C. for 10 seconds.

  A commercial item can also be used for the label substrate. As a commercially available plastic film, for example, as a biaxially stretched polyethylene terephthalate (PET) film, “Lumirror” manufactured by Toray Industries, Inc., as a biaxially stretched polypropylene (OPP) film, “Trephan” manufactured by Toray Industries, Inc. “A1” manufactured by Gunze Co., Ltd., “U-1” manufactured by Tosero Co., Ltd., and the like can be used.

  The heat-sensitive label of the present invention is preferably provided with a printing layer in addition to the adhesive layer. The printing layer is a layer displaying a product name, an illustration, handling precautions, and the like, and can be formed by a conventional printing method such as letterpress printing, silk screen printing, gravure printing, flexographic printing, and the like. In the present invention, gravure printing is preferably used in that the printing layer and the adhesive layer can be formed in one step, the printing speed is high, and the production efficiency can be improved. The printing ink used for forming the printing layer is composed of, for example, a pigment, a binder resin, and a solvent. Examples of the binder resin include acrylic, urethane, polyamide, vinyl chloride-vinyl acetate copolymer, cellulose, and nitrocellulose. A general resin such as a system can be used. The thickness of the printing layer is not particularly limited and is, for example, about 0.1 to 10 μm.

  In the heat-sensitive label of the present invention, the adhesive layer and the print layer do not need to be provided on the entire surface of the label substrate, and may be provided on a part of the label substrate. Among them, the adhesive layer is strip-shaped when it is provided on the entire surface, or in the direction of the height direction of the container after being wound around the portion of the label that is both ends in the direction of the circumferential direction of the container after being wound Is preferable. When the adhesive layer is provided in a strip shape at both ends in the label width direction as in the latter, one end of the label is attached to the container, the label is wound, and the other end is the label surface on the one end. It is preferably used as a type of label (wrapping label) that is attached by being overlapped with and attached to. Moreover, the adhesive bond layer different from this invention can be used except the adhesive bond layer affixed on the container surface.

  The laminated structure of the adhesive layer and the printing layer is not particularly limited, and an adhesive layer may be provided on the printing layer (label base material / printing layer / adhesive layer) or on the label base material. A portion where only the adhesive layer is provided (label base material / adhesive layer) and a portion where only the printing layer is provided (label base material / printing layer) may exist separately, and their lamination The configurations may be combined. Among these, from the viewpoint of the effect of high adhesiveness between the adhesive layer of the present invention and the label base material, the adhesive layer is preferably provided directly on the base material. In particular, the adhesive layer provided for attaching to an adherend such as a container is preferably provided directly on the label substrate. Further, a label having a layer structure of printing layer / label base material / adhesive layer in which a printing layer is laminated on one surface side of the label base material and an adhesive layer is laminated on the opposite surface side is preferably used. In addition, from the viewpoint of exhibiting the effect of the present invention, the heat-sensitive label has a layer configuration in which the adhesive layer is at least partially included in the outermost layer. If there is no portion where the adhesive layer is the outermost layer, the effect of the present invention cannot be exhibited. In particular, the heat-sensitive label of the present invention preferably has at least two separated portions where the adhesive layer becomes the outermost layer.

  In addition, in the thermosensitive label of this invention, you may provide a primer coat layer between a printing layer and a label base material from a viewpoint of the adhesive improvement of a printing layer and a label base material. The primer coat layer can be formed of a known primer such as an acrylic primer, a polyester primer, an isocyanate primer (two-component mixed primer, etc.), and the like. The thickness of a primer coat layer can be suitably selected in the range which does not impair transparency and the handleability of a label, For example, 0.1-3.0 micrometers is preferable.

  The thermal label of the present invention may be provided with an overcoat layer from the viewpoint of protecting the printed layer or imparting gloss. The overcoat layer is usually provided on the outside (on the side not in contact with the container) when mounted on a container, and is a transparent UV curable varnish, polyester resin, acrylic resin, epoxy resin, and silicone with a lubricant added as necessary. It can be formed by coating or printing a resin or the like. In the case where the adhesive layer at the other end of the thermosensitive label is laminated and bonded to one end, the overcoat layer is preferably formed so as to avoid the region where the adhesive layer at the other end is adhered. . Although the thickness of an overcoat layer is not specifically limited, 0.1-3.0 micrometers is preferable.

  The thermosensitive label of the present invention is provided with a coating layer, a resin layer, an anchor coat layer, an overlaminate layer, etc. in addition to the label base material, the print layer, the adhesive layer, the primer coat layer, and the overcoat layer. A layer of non-woven fabric, paper, plastic, etc. may be provided as necessary.

  The heat-sensitive label of the present invention has no adhesive residue and has good adhesion and easy peelability. Adhesion was achieved by bonding a label activated by heating above the activation temperature (for example, activation temperature +5 to + 20 ° C.) to a plastic sheet having the same material and physical properties as the surface of the container or label substrate. About a sample, it can evaluate by the test according to JISK6854-3 (T-type peeling) [peeling speed (tensile speed) 300mm / min], and adhesive strength with respect to the container surface and adhesive strength with respect to a label base material (details are mentioned later) Depending on the test method). The adhesive strength of the adhesive layer based on the above method to the plastic sheet is preferably 0.5 to 3 N / 15 mm, more preferably 0.7 to 3 N / 15 mm. When the adhesive strength is less than 0.5 N / 15 mm, a mounting failure such as inability to adhere the thermosensitive label to the container tends to occur. On the other hand, if it exceeds 3 N / 15 mm, it is difficult to peel off the thermosensitive label from the container after use, or adhesive residue may be generated, which is not preferable. Among the above, it is preferable that the adhesive strength to the material used for the container (particularly preferably polyethylene terephthalate (PET)) and the adhesive strength to the material used for the label substrate (particularly preferably polypropylene (PP)) are in the above ranges. .

  The heat-sensitive label of the present invention has a good adhesive residue inhibiting property (adhesive residue preventing property). The adhesive residue deterrence indicates whether or not there is adhesive residue on the plastic sheet after affixing and peeling the label according to the T-type peel test using a plastic sheet (particularly preferably PET) having the same material and physical properties as the container surface. It can be evaluated by visual observation. Usually, when a solid plasticizer is added to give a delay property, adhesive residue is easily generated. However, in the present invention, the delay property and the paste mainly depend on the balance of the components (A), (B), and (C). It is possible to achieve both remaining deterrence. Therefore, adhesive strength can be suppressed by improving the film strength while maintaining excellent workability and sufficient adhesive force.

  The heat-sensitive label of the present invention has good blocking resistance. The term “blocking” as used in the present invention refers to a phenomenon in which the surface of the heat-sensitive adhesive layer and the surface overlapped with each other when the label original fabric provided with the heat-sensitive adhesive layer is wound up and stored in a roll shape, and rewinded. This leads to a decrease in workability and label quality. Usually, the heat-sensitive adhesive layer does not exhibit adhesiveness at room temperature, but blocking may occur due to a winding pressure or the like. The blocking resistance here refers to a sample stored for 7 minutes at room temperature (23 ° C.) with the pressure on the adhesive layer side of the label and the surface on the label base material side being applied and a pressure of 20 MPa being applied. It can evaluate by the below-mentioned blocking resistance evaluation test. In the present invention, good blocking resistance is expressed mainly by the balance of components (A), (B), and (C).

  In addition, the heat-sensitive label of the present invention usually includes a surfactant so that the adhesive is emulsified, and thus has an alkali peelability. Here, the alkali releasability means the property that the heat-sensitive label can be peeled from the surface of the adherend by immersing the heat-sensitive label attached to the adherend in an alkaline solution and dissolving the adhesive. The heat-sensitive label of the present invention can be easily peeled off from the adherend by, for example, a method of immersing it in an alkaline solution after being attached to the adherend. As the alkaline solution, for example, a 1.5% by weight NaOH aqueous solution can be used, and in particular, alkaline hot water having a temperature of about 80 to 95 ° C. is preferably used.

  The heat-sensitive label of the present invention can be used by attaching an adhesive layer to an adherend. The adherend is not particularly limited and may be any of plastic, glass, metal, etc., but is made of a polyester resin such as polyethylene terephthalate (PET), or a plastic made of polyolefin resin such as high density polyethylene or polypropylene. Those made of are preferred. Among these, an adherend made of a polyester resin such as PET is preferable.

  Examples of the adherend include bottles for soft drinks such as PET bottles, milk bottles for home delivery, food containers such as seasonings, bottles for alcoholic beverages, pharmaceutical containers, containers for chemical products such as detergents and sprays, cups, etc. Containers such as noodle containers are included. The shape of the container is not particularly limited, and includes various shapes such as a cylindrical shape, a square bottle, and a cup type. In particular, a plastic container made of a polyester resin such as polyethylene terephthalate (PET) or a polyolefin resin such as high density polyethylene or polypropylene is preferable, and a polyester resin container is particularly preferable.

  The heat-sensitive adhesive used in the heat-sensitive label of the present invention has adhesiveness, easy peelability, and adhesive residue deterrence. Therefore, after directly bonding one end of the label to the adherend, the other end is wrapped around the adherend. It can be preferably used as a wrapping label that adheres to one end portion (label surface) of the adhesive. When used in this application, an adhesive used on the side that adheres to the bottle (excellent adhesiveness and adhesive residue deterrence are required) However, it can be used as any of the adhesives used on the side that adheres to the label surface (excellent adhesiveness and easy peelability are required). For this reason, it is not necessary to use two different types of adhesives in the label manufacturing process, which is preferable from the viewpoint of cost and productivity. The heat-sensitive adhesive of the present invention has particularly excellent adhesiveness, easy peelability, and adhesive residue deterrence to polyester resins (especially PET) and polyolefin resins (especially PP). It is preferable because it can be used as a heat-sensitive label having a label substrate, and can exhibit excellent characteristics with respect to both the container and the label substrate when mounted on a container made of a polyester resin.

  The labeled container of the present invention is formed by mounting the thermosensitive label of the present invention on the container. The thermosensitive label may be attached to the entire surface of the container or may be attached to a part thereof. The heat-sensitive label can be attached to the container by a known or conventional method. For label mounting, for example, the adhesive layer side of the thermal label is placed on the container surface, a hot plate is pressed from the label base, or the thermal label is held on the heating drum by suction from the label base. In general, a labeler (label automatic) is applied by activating the adhesive layer by applying heat to the adhesive layer with heat from the drum or a heat source such as infrared rays, and then applying it to the container by pressing. A sticking machine: for example, those described in JP-A-8-58755, JP-A-11-321831 and JP-A-2000-25725 can be used. The heating temperature is appropriately selected according to the activation temperature of the adhesive layer, and is preferably 70 to 150 ° C, and more preferably 80 to 120 ° C, for example.

[Methods for measuring physical properties and methods for evaluating effects]
(1) Adhesive strength (vs. OPP, v. PET)
A strip-shaped test piece having a width of 15 mm and a length of 40 mm was prepared from the heat-sensitive labels obtained in Examples and Comparative Examples. Here, the width direction of the test piece is the height direction of the thermal label, and the length direction of the test piece is the width direction of the thermal label. The surface of the test piece on the adhesive layer side is a polypropylene (OPP) sheet (manufactured by Toray Industries, Inc., trade name “Trephan”), and a polyethylene terephthalate (PET) sheet (manufactured by Toyobo Co., Ltd., trade name). “A1101”, 100 μm (non-treated surface)), adhesive area: 10 mm (peeling direction) × 15 mm (width direction), temperature 100 ° C., pressure 0.15 MPa, time 0.5 sec. Crimped and used for measurement.
Using a tensile tester (manufactured by Shimadzu Corporation, trade name “Autograph”), the above-mentioned pasted samples (thermal label / OPP sheet, thermal label / PET sheet) were peeled off by a method according to JIS K 6854-3. A test (peeling speed 300 mm / min) was performed, and the adhesive strength of the thermal label (vs. OPP and PET) (N / 15 mm) was measured.

(2) Blocking resistance (blocking deterrence) evaluation test One test piece and a base film (label base material) prepared by the same method as in the above-described evaluation of adhesive strength were combined with an adhesive layer of the base film and the test piece. The test piece and the substrate film were peeled by hand and evaluated according to the following criteria.
No resistance or peels naturally: Good blocking resistance (○)
Although there is a sense of resistance, the glue (adhesive layer) does not transfer to the substrate film on the other side: Usable level (△)
There is a sense of resistance, and the glue (adhesive layer) is transferred to the base film on the other side: poor blocking resistance (×)

(3) Adhesive residue deterrence (vs. PET)
The heat-sensitive labels obtained in Examples and Comparative Examples were visually observed for the presence of adhesive residue on the surface of the PET sheet after the adhesive strength was measured in (1) above, and evaluated according to the following criteria.
No adhesive residue was seen: Good adhesive residue deterrence (○)
Slight adhesive residue was observed (less than 10% of the applied area): Usable level (△)
A large amount of adhesive residue was observed (more than 10% of the applied area)

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Tables 1, 2 and 4 show the blending amounts (contents) and evaluation results of the components of Examples and Comparative Examples. Details of each component used in Table 1, Table 2 and Table 4 are shown in Table 3. In addition, in the table | surface, all the compounding quantities of each component are represented by the weight part of solid content (nonvolatile content) of each component.

Example 1
(Label substrate)
As the label substrate, a biaxially stretched polypropylene (OPP) film (manufactured by Toray Industries, Inc., trade name “Trephan”, thickness 50 μm) was used.
(Printing ink)
As the printing ink, urethane solvent type white ink (manufactured by Dainichi Seika Kogyo Co., Ltd.) was used.
(Heat sensitive adhesive)
According to the blending amount of Table 1, 25 parts by weight (in terms of solid content) of ethylene-vinyl acetate copolymer resin emulsion (manufactured by Sumitomo Chemical Co., Ltd., trade name “Sumikaflex 467HQ”) as component (A), as component (B) Carboxy-modified styrene-butadiene latex (manufactured by Nippon A & L Co., Ltd., trade name “Nalstar SR-100”) 25 parts by weight (in terms of solid content), component (C) dicyclohexyl phthalate (DCHP) (Osaka Organic Chemical Co., Ltd.) 50) parts by weight (in terms of solid content) was dispersed in water to obtain an emulsion-type heat-sensitive adhesive.
(Thermal label)
On one surface of the label base material, the printing ink was printed by gravure printing to form a printing layer (thickness 2 μm). Subsequently, the heat-sensitive adhesive is applied by gravure printing with a width of 15 mm to both ends of one side of the label substrate (the surface on the printing layer side) to form an adhesive layer (thickness 10 μm) to obtain a heat-sensitive label. It was.
As shown in Table 1, the obtained thermosensitive label had excellent adhesiveness, blocking resistance, and adhesive residue deterrence.

Examples 2-5
A thermosensitive label was produced in the same manner as in Example 1 except that the types of the component (A) and the component (B) were changed as shown in Table 1.
As shown in Table 1, the obtained thermosensitive label had excellent characteristics.

Example 6
As shown in Table 1, a thermosensitive label was produced in the same manner as in Example 4 except that a tackifier (manufactured by Yasuhara Chemical Co., Ltd., trade name “Nanolet R-1050”) was added to the thermosensitive adhesive.
As shown in Table 1, the obtained thermosensitive label had excellent characteristics.

Comparative Examples 1-4
A thermosensitive label was produced in the same manner as in Examples 1 to 4, using only the component (A) and the component (C) without using the component (B).
As shown in Table 1, the obtained thermosensitive label had poor adhesion to OPP.

Comparative Example 5
A thermosensitive label was produced in the same manner as in Example 1 except that the component (A) was not used and only the component (B) and the component (C) were used.
As shown in Table 1, the obtained thermosensitive label had poor adhesion to OPP.

Comparative Example 6
A thermosensitive label was produced in the same manner as in Example 1 except that the component (C) was not used and only the component (A) and the component (B) were used.
As shown in Table 1, the obtained thermosensitive label was inferior in adhesion to PET and OPP and blocking resistance.

Examples 7-15, Comparative Examples 7-15
As shown in Table 2 and Table 4, component (A) ethylene-vinyl acetate-acrylic copolymer resin emulsion (manufactured by Sumitomo Chemical Co., Ltd., trade name “Sumikaflex 900HL”), component (B) carboxy Modified styrene-butadiene latex (manufactured by Nippon A & L Co., Ltd., trade name “Nalstar SR-100”), component (C), dicyclohexyl phthalate (DCHP), and emulsion types with various blending ratios A heat sensitive adhesive was obtained.
A heat-sensitive label was obtained in the same manner as in Example 1 using the heat-sensitive adhesive.

Example 16
As shown in Table 4, component (A) ethylene-vinyl acetate-acrylic copolymer resin emulsion (manufactured by Sumitomo Chemical Co., Ltd., trade name “Sumikaflex 900HL”), component (B) carboxy-modified styrene- The blending amount of butadiene latex (trade name “Nalstar SR-100” manufactured by Nippon A & L Co., Ltd.) was changed, and further, as component (C), tribenzoic acid glyceride (manufactured by UNITEX CHEMICAL CORPORATION, trade name “UNIPLEX 260”). ) Was used to obtain an emulsion type heat sensitive adhesive.
A heat-sensitive label was obtained in the same manner as in Example 1 using the heat-sensitive adhesive.

From Table 1, in the case of the two-component system of component (A) and component (C) or component (B) and component (C) (Comparative Examples 1 to 5), none of the adhesive strength to OPP is obtained. On the other hand, it can be seen that by using the three components (A) to (C) in combination, high adhesive strength that cannot be obtained by the two-component system can be obtained (Examples 1 to 6).
From Table 2 and Table 4, only when the blending ratio of the components (A) to (C) is within the specified range of the present invention, the adhesion to OPP and PET is specifically improved, and further, blocking resistance, glue It can be seen that the effect of remaining deterrence can be obtained.

  Moreover, the thermosensitive label obtained in Examples 1-16 is piled up on the surface of the PET bottle (Toyo Seikan Co., Ltd.) and one end thereof is pressed with a hot plate (temperature 100 ° C.) from the label substrate side. After the adhesive layer is activated and pressure-bonded by wrapping the thermosensitive label around the bottle, the other end is overlaid on one end and the hot plate is pressed from the label substrate side to activate and pressure-bond the adhesive layer. Thus, a labeled container was obtained.

Claims (5)

  A thermosensitive label in which an adhesive layer is laminated on a label base material, the adhesive layer containing an ethylene-vinyl acetate resin (A), a synthetic rubber (B) and a solid plasticizer (C), Mixing ratio [(A) / (B)] (weight ratio in terms of solid content) of vinyl acetate resin (A) and synthetic rubber (B) is 20/80 to 80/20, ethylene-vinyl acetate resin (A ) And synthetic rubber (B) total amount [(A) + (B)] and solid plasticizer (C) mixing ratio [{(A) + (B)} / (C)] (in terms of solid content) A heat-sensitive label, which is formed from an emulsion-type heat-sensitive adhesive having a weight ratio of 25/75 to 65/35.   A thermosensitive label in which an adhesive layer is laminated on a label base material, the adhesive layer containing an ethylene-vinyl acetate resin (A), a synthetic rubber (B) and a solid plasticizer (C), Mixing ratio [(A) / (B)] (weight ratio in terms of solid content) of vinyl acetate resin (A) and synthetic rubber (B) is 60 / 40-80 / 20, ethylene-vinyl acetate resin (A ) And synthetic rubber (B) total amount [(A) + (B)] and solid plasticizer (C) mixing ratio [{(A) + (B)} / (C)] (in terms of solid content) A heat-sensitive label, which is formed from an emulsion-type heat-sensitive adhesive having a weight ratio of 65/35 to 75/25.   A labeled container in which the thermosensitive label according to claim 1 or 2 is mounted on a container composed of a polyester resin or a polyolefin resin, wherein the label substrate is composed of a polyester resin or a polyolefin resin.   The labeled container according to claim 3, wherein the label base material is made of a polyolefin resin, and the container is made of a polyester resin.   The label according to claim 3 or 4, wherein one end of the label is affixed to the container, the label is wound around the container, and the other end is overlapped and bonded to the surface of the label base material on the one end. With container.