JP5100204B2 - Thermal labels and labeled containers - Google Patents

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 to which the heat-sensitive label is attached. More specifically, the adhesive layer is a delayed heat-sensitive adhesive. The present invention relates to a heat-sensitive label that is formed.

  A delayed heat-sensitive adhesive used for a heat-sensitive label generally contains a thermoplastic resin, a tackifier, and a solid plasticizer as constituent components. Such a heat-sensitive label maintains its adhesiveness even when the heat applied at the time of application is lost, and thus has excellent application stability. For example, a product name, a design, an explanation about contents, etc. are printed, and polyethylene terephthalate It is used by being attached to the side surface of a plastic container body such as a (PET) bottle.

  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 and the like, the label can be easily peeled off after use of the container, and the adhesive does not remain on the container side at the time of peeling (so-called “no adhesive residue”) is required. That is, the thermosensitive adhesive is required to have conflicting characteristics such as high adhesiveness, easy peelability, and suppression of adhesive residue.

  Japanese Patent Application Laid-Open No. 2004-219621 discloses a label in which one end of a label is directly bonded to a bottle and the other end is bonded to one end portion (label surface) of the label, and no adhesive remains on one end bonded to the bottle. A container label is disclosed that uses an adhesive having excellent adhesive strength at the other end to which the adhesive is adhered to the label surface, and achieves both adhesion and easy peelability. 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, a heat-sensitive adhesive that has high adhesiveness, easy peelability, and adhesive residue deterrence, is easy to handle, and has high productivity is not yet known.

JP 2004-219621 A

  The object of the present invention is to exhibit blocking resistance and sufficient adhesiveness, so that even if it is peeled off by hand, no adhesive remains on the container, and it has excellent workability due to the delay property. Provided are a thermosensitive label capable of easily peeling a label and an adhesive from a body, and a labeled container equipped with the label.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the emulsion type heat-sensitive adhesive in which the base polymer is composed of a specific resin has excellent adhesion and blocking resistance, easy peeling, and peeling. The present invention was completed by finding that a heat-sensitive label that achieves suppression of adhesive residue at the time and that is excellent in workability due to the delay property can be obtained.

That is, the present invention relates to a heat-sensitive label in which an adhesive layer and a printed layer are laminated on a label base material, and the adhesive layer is a base polymer composed of an acrylic resin and an olefin resin, and a solid plasticizer , And an emulsion-type heat-sensitive adhesive containing a tackifier, and the mixing ratio of the acrylic resin and the olefin resin constituting the base polymer is the former / the latter (weight ratio in terms of solid content) = 20/80 to 80/20, the glass transition temperature of the acrylic resin is -60 ° C to 40 ° C, and the olefin resin is an olefin selected from an acid-modified olefin resin and a halogenated olefin resin A heat-sensitive label that is a resin is provided.

In the heat-sensitive label of the present invention, the melting point of the olefin resin is preferably about 30 to 140 ° C. As the olefin resin, a polypropylene resin or the like is preferably used.

Furthermore, the present invention is a labeled container in which the heat-sensitive label of the present invention is attached to a container made of a polyester resin or an olefin resin, and the label substrate constituting the heat-sensitive label is a polyester resin or an olefin resin. A labeled container is provided. Preferably, a container with a label is used in which the container is made of a polyester-based resin and the label base material constituting the thermosensitive label is an olefin-based resin. The container with a label of the present invention is one in which one end of the label is attached to the container, the label is wound around the container, and the other end is overlapped and attached to the surface of the label base material on the one end. It may be.
In addition to the above invention, the present specification includes a heat-sensitive label in which an adhesive layer and a printed layer are laminated on a label base material, and the adhesive layer is composed of an acrylic resin and an olefin resin. Also described is a heat sensitive label formed of an emulsion type heat sensitive adhesive comprising a base polymer, a solid plasticizer, and a tackifier.

  The heat-sensitive label of the present invention can be easily peeled off without leaving glue on the adherend when the label is peeled off while having excellent adhesiveness. In addition, blocking is less likely to occur at room temperature, and the adhesive layer can be formed in the same process as the printing process, which is advantageous in terms of cost. Furthermore, since the adhesive strength is maintained for a certain time after activation by heating (the open time is long), workability is good. Therefore, it is particularly useful as a heat-sensitive label used for PET bottles and the like. Labeled containers with such heat-sensitive labels attached to the containers can be recycled easily because the heat-sensitive labels can be easily peeled off from the container and quickly separated and collected by a simple method of immersing in alkali after use. It is extremely excellent.

  The heat-sensitive label of the present invention has a layer structure in which an adhesive layer and a printing layer are laminated on a label substrate.

  The adhesive layer is formed of an emulsion-type heat-sensitive adhesive including a base polymer composed of an acrylic resin and an olefin resin, a solid plasticizer, and a tackifier. 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 having a delay property that is activated by heat and exhibits 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. In addition, 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.

  The heat-sensitive adhesive in the present invention contains an emulsion-type heat-sensitive adhesive containing a base polymer, a solid plasticizer, and a tackifier. The base polymer is composed of at least an acrylic resin and an olefin resin. Since the heat-sensitive adhesive is used in combination with an acrylic resin and an olefin resin, the adhesiveness with the base material is improved, and furthermore, the adhesive residue when used as a label can be efficiently suppressed, respectively. An advantageous effect that cannot be obtained when used alone can be exhibited.

  The acrylic resin as the base polymer has an effect of imparting high adhesive force and excellent cohesive force by using an olefin resin in combination. In particular, when used in combination, it exhibits high adhesion to a label substrate or adherend made of an olefin resin or a polyester resin, and when the label is peeled off, the adhesive residue on the adherend can be remarkably suppressed.

  Examples of the monomer component constituting the acrylic resin include (meth) acrylic such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Acid alkyl ester; carboxyl group-containing polymerizable unsaturated compounds such as (meth) acrylic acid, crotonic acid, itaconic acid, fumaric acid and maleic acid, or anhydrides thereof. Furthermore, as a monomer component which comprises acrylic resin, hydroxyl group containing (meth) acrylic acid ester, such as 2-hydroxymethyl (meth) acrylate, (meth) acrylic acid cycloalkyl ester, ( Polymerizable unsaturated compounds such as functional group-containing (meth) acrylic acid esters such as (meth) acrylic acid amide derivatives and (meth) acrylic acid dialkylaminoalkyl esters can be used.

  Examples of the acrylic resin include a homopolymer composed of the above monomer components or a copolymer in which a plurality of monomer components are combined, and the copolymer includes a random polymer, a block polymer, and a graft polymer. Or any other form. Copolymer components include styrene compounds such as styrene, vinyltoluene, and α-methylstyrene; vinyl esters such as vinyl acetate and vinyl propionate; vinyl halides such as vinyl chloride; polyolefins such as ethylene and propylene, and dienes Polymerizable unsaturated compounds such as catechol can be used. Specific examples of the acrylic resin include, for example, poly (meth) acrylic acid ester, poly (meth) acrylic acid; acrylic resin such as (meth) acrylic acid ester- (meth) acrylic acid; ethylene- (meth) acrylic Ethylene-acrylic resins such as acid esters and ethylene- (meth) acrylic acid; Styrene-acrylic resins such as styrene- (meth) acrylic acid esters and styrene- (meth) acrylic acid; Vinyl acetate- (meth) acrylic acid Examples include esters, vinyl acetate- (meth) acrylic acid; vinyl acetate-acrylic resins; ethylene-styrene- (meth) acrylic acid esters, vinyl acetate-styrene- (meth) acrylic acid, and the like. Among these, a styrene-acrylic resin is preferably used because it can provide good adhesion to polyester.

  The glass transition temperature (Tg) of the acrylic resin is, for example, about −60 to 60 ° C., preferably −50 to 50 ° C., more preferably −40 to 40 from the viewpoints of adhesion to a substrate and a container and blocking resistance. It is about ℃. If the glass transition temperature is too low, the anti-blocking property is reduced, and adhesive residue tends to remain. If the glass transition temperature is too high, the efficiency (labelability) at the time of application is reduced and the solubility in hot alkaline water is reduced. Separation may be difficult. The glass transition temperature can be controlled by appropriately selecting the type and composition ratio of monomer components.

  The acrylic resin is generally provided in the form of an emulsion dispersed in water, alcohol or the like. Such an acrylic resin emulsion can be prepared by a method of emulsifying a resin in which a corresponding monomer is produced by a solution polymerization reaction or the like, but is usually prepared by emulsion polymerization of a corresponding monomer. There are many cases. As such an acrylic resin emulsion, “Polytron Z-130 (Tg-56 ° C.)” manufactured by Asahi Kasei Chemicals Corporation, “Epocross K2010E (Tg-50 ° C.)” manufactured by Nippon Shokubai Co., Ltd., Shin-Nakamura Chemical Co., Ltd. “New Coat FH3550 (Tg-40 ° C.)”, “New Coat FH251HN (Tg-25 ° C.)”, “New Coat K-2 (Tg-26 ° C.)”, Vestex L-1HN (Tg 0 ° C.) ), “Vestex HCR-120 (Tg 32 ° C.)” and “Epocross K2030E (Tg 50 ° C.)” commercially available from Nippon Shokubai Co., Ltd. are available.

  When used together with the acrylic resin, the olefin resin in the present invention can constitute a heat-sensitive adhesive exhibiting high adhesive force and excellent cohesive force and suppressing adhesive residue. In particular, when used in combination, a high adhesive force can be exhibited with respect to a label substrate or an adherend made of an olefin resin or a polyester resin, and the adhesive residue at the time of peeling can be remarkably suppressed.

  Examples of such an olefin resin include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, butene-1, octene-1, 4-methyl-1-pentene; cyclopentene, cyclohexene, 1,4- Chain or cyclic polyenes such as hexadiene, 1,5-hexadiene, divinylbenzene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 5-vinyl-2-norbornene; olefins such as aromatic compounds such as styrene Monomers or copolymers; copolymers of the olefinic monomers with other monomer components such as unsaturated carboxylic acids or esters thereof (for example, maleic anhydride, (meth) acrylic acid, and esters thereof), etc. Is mentioned. The copolymer may be in any form such as a random polymer, a block polymer, and a graft polymer.

  Specific examples of such olefin resins include polypropylene resins; polyethylene, copolymers of ethylene and other monomer components (ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-propylene- Α-olefin copolymer such as butene-1 copolymer; copolymer with monomers other than olefin such as ethylene- (meth) acrylate copolymer, ethylene-maleic anhydride copolymer, and the like Other α-olefin-based (co) polymers (polybutene-1, ethylene-butene-1 copolymer, polymethylpentene-1, etc.); olefins and other monomer components Examples thereof include polymers and derivatives thereof. Among these, a polypropylene resin is preferably used.

  Typical polypropylene resins include, for example, propylene homopolymers; copolymers of propylene and one or more monomers other than propylene; and derivatives thereof. Examples of monomers other than propylene include, for example, olefinic monomers excluding propylene (alpha-olefins having 2 to 20 carbon atoms such as ethylene, butene-1, octene-1, 4-methyl-1-pentene); cyclopentene, cyclohexene, Linear or cyclic polyenes such as 1,4-hexadiene, 1,5-hexadiene, divinylbenzene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 5-vinyl-2-norbornene; aromatic compounds such as styrene Maleic anhydride, (meth) acrylic acid, and unsaturated carboxylic acids such as esters thereof or esters thereof.

  Specific examples of such polypropylene resins include polypropylene; propylene-olefin copolymers such as ethylene-propylene copolymer, propylene-butene-1 copolymer, and ethylene-propylene-butene-1 copolymer; Propylene- (meth) acrylate copolymer, propylene-maleic anhydride copolymer, ethylene-propylene-maleic anhydride copolymer, ethylene-propylene-butene-1-maleic anhydride copolymer, ethylene-propylene-diene -Propylene-type (co) polymers, such as a copolymer with other monomer components, such as a maleic anhydride copolymer. As a derivative of the propylene-based (co) polymer, an acid-modified polypropylene resin obtained by modifying the propylene-based (co) polymer with an acid; and one of hydrogen constituting the propylene-based (co) polymer such as chlorinated polypropylene And halogenated polypropylene resin in which part is substituted with halogen such as chlorine. These polypropylene resins can be used alone or in combination of two or more.

  Of these, derivatives of olefinic (co) polymers such as acid-modified olefinic resins and halogenated olefinic resins are preferable, maleic anhydride-modified olefinic resins are particularly preferable, and maleic anhydride obtained by graft polymerization of maleic anhydride. A modified olefin resin is more preferable. In addition, acid-modified polypropylene and halogenated polypropylene are preferable in terms of excellent adhesion to polypropylene, particularly maleic anhydride-modified polypropylene resin is preferable, and maleic anhydride-modified polypropylene resin grafted with maleic anhydride is more preferably used. It is done. In addition, the acid-modified polypropylene resin is preferable in that it does not contain chlorine or the like that has a high environmental load. Furthermore, acid-modified amorphous polypropylene having an amorphous structure is preferable in terms of excellent adhesiveness.

  Among them, the olefin resin used in the present invention preferably has a melting point (Tm) of about 30 to 140 ° C., and particularly preferably about 60 to 120 ° C. If the melting point is too high, the adhesive strength tends to decrease, and if the melting point is too low, the adhesive residue and blocking resistance may decrease. From the same viewpoint, as the olefin resin used in the present invention, those having a weight average molecular weight of, for example, 3000 to 200000, preferably 5000 to 150,000, more preferably about 10,000 to 100,000 can be used.

  Olefin resins such as polypropylene resins are prepared, for example, by emulsion polymerization of corresponding monomers, and are provided in the form of an emulsion dispersed in water, alcohol or the like. As such a polypropylene resin emulsion, for example, “Auroren AE-201 (Tm 60-70 ° C.)”, “Auroren AE-301 (Tm 60-70 ° C.)” manufactured by Nippon Paper Chemical Co., Ltd., Toyo Kasei Co., Ltd. Commercially available products such as “Hardlen NA-1001 (Tm100 ° C.)” are available.

  The mixing ratio of the acrylic resin and the olefin resin is a weight ratio in terms of solid content, for example, the former / the latter = about 10/90 to 90/10, preferably about 20/80 to 80/20. If the content of the olefin-based resin is too low, the adhesive strength to the label and adherend (container) surface tends to decrease, and when the label base materials are bonded together, the bonded portion of the label may be easily peeled off. If it is too high, the adhesive strength to the label and the adherend (container) surface tends to decrease, the blocking resistance tends to decrease, and the workability tends to be impaired, and troubles such as peeling of the label are likely to occur. .

  The solid plasticizer 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, that is, a base polymer, an olefin resin, and a tackifier. It has a role of plasticizing to develop and maintain adhesiveness.

  As such a solid plasticizer, known solid plasticizers can be used, such as diphenyl phthalate, dihexyl phthalate, dicyclohexyl phthalate (DCHP: melting point 66 ° C.), dihydroabiethyl phthalate, dimethyl isophthalate. Phthalate compounds such as trimethylolethane tribenzoate, trimethylolpropane tribenzoate (melting point 88 ° C.), glyceride tribenzoate (melting point 73 ° C.), pentabenzoate tribenzoate, etc. Sucrose octaacetate, tricyclohexyl ketenoate, triethylene glycol bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate)] (melting point 77 ° C.), 1,6-hexanediol bis [ 3- (2,5-di-tert-butyl-4-hydroxyphenyl) Fatty acid ester compounds such as (Lopionate) (melting point 103 ° C.); sulfonic acid ester compounds such as N-cyclohexyl-p-toluenesulfonic acid amide; phosphate ester compounds, hindered phenol compounds, triazole compounds, hydroquinone It can be selected from system compounds.

  As the solid plasticizer in the present invention, those having a melting point of about 50 to 100 ° C. are preferably used. Of these, phthalate ester compounds and the like are preferable, and DCHP and the like are particularly preferably used.

  The content of the solid plasticizer in the present invention is, for example, 0.1 to 100 parts by weight, preferably 5 to 90 parts by weight, more preferably 10 to 85 parts by weight based on 100 parts by weight of the total solid content of the base polymer contained in the main agent. It is often used in an amount of about 20 to 80 parts by weight. If the content of the solid plasticizer is too small, the delayed tackiness is insufficient (the open time is short) and the workability may be lowered. Moreover, when there is too much content, cohesive force may fall and adhesive residue may be produced.

  The heat-sensitive adhesive used in the present invention further contains a tackifier. The tackifier exhibits an effect of improving adhesiveness. 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 resin are added to rosins, resin acid dimers), terpene resins (terpene resins, aromatic modified terpenes) 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 in the present invention is also available on the market. For example, “YS Polystar” manufactured by Yashara Chemical Co., Ltd., “Pine Crystal” manufactured by Arakawa Chemical Co., Ltd., “Tamanol E-200NT (softening point 150 ° C.)” , “Narret R-1050 (softening point 105 ° C.)” manufactured by Yashara Chemical Co., Ltd., and the like.

  The content of the tackifier is, for example, 0.1 to 100 parts by weight, preferably 5 to 90 parts by weight, more preferably about 10 to 85 parts by weight, and particularly 20 to 100 parts by weight of the solid content of the base polymer. It is often used at about 80 parts by weight. When the content of the tackifier is too large, adhesive residue is generated or the adhesive strength is reduced. When the content is too small, the delay property is inferior (open time is shortened), and workability is deteriorated.

  In the present invention, an anti-blocking agent or the like may be added to the heat-sensitive adhesive. As such an antiblocking agent, for example, inorganic particles such as calcium carbonate, clay, talc, silica, alumina, mica, alumina sol, colloidal silica; particles made of an organic compound such as paraffin can be used. In addition to the above, the heat-sensitive adhesive used in the present invention may contain known additives such as a dispersant, a thickener, an antifoaming agent, and a leveling agent, if necessary.

  The temperature at which the heat-sensitive adhesive 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 having an activation temperature of less than 60 ° C. is used, blocking is likely to occur at room temperature (such as when the label is wrapped around the container body), and if the activation temperature is too high, the container body is easily damaged. Both are inferior in workability. 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. When used as a heat-sensitive label, it can be easily attached to an adherend. The activation temperature can be adjusted by appropriately selecting the type of base polymer and olefin resin, the type and amount of tackifier and wax, and other additives. In the present invention, the activation temperature of the adhesive layer is a temperature that produces an adhesive strength of 0.7 N / 15 mm or more when measured according to JIS K 6854-3.

  The heat-sensitive adhesive generally exhibits tackiness when heated at a temperature higher than the activation temperature. In particular, since the heat-sensitive adhesive used in the present invention can exhibit tackiness in a short time after heating, the heat-sensitive label formed with the heat-sensitive adhesive is applied to an adherend using a high-speed labeler. Since it can be applied stably, there is an advantage that productivity can be improved.

  The heat-sensitive adhesive in the present invention can be produced by a known method using the above components. The base polymer (acrylic resin and olefin resin), which is a constituent of the heat-sensitive adhesive, is usually used in the form of an aqueous emulsion in which fine particles having an average particle size of about 1 μm or less are dispersed in a dispersion medium. The solid plasticizer 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. As the tackifier, an aqueous dispersion or an aqueous emulsion is used. The heat-sensitive adhesive can be prepared by mixing and stirring these. 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, acrylic emulsion, olefin emulsion, solid plasticizer, tackifier and other components are charged simultaneously into a container such as a stirring and mixing tank, or sequentially or continuously with stirring. And can be obtained by stirring and mixing uniformly.

  The adhesive layer is formed of the above heat sensitive adhesive. The adhesive layer is formed by applying the heat-sensitive adhesive on at least one side of the label base material by a known application method such as a bar coater, gravure coater, flexo coater, roll coater, curtain coater, spray coater, brush coating, or die coating. It can be formed by 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 about 2 to 20 μm. When the coating thickness is thin, it is difficult to obtain a sufficient adhesive force, and when the coating thickness is too thick, adhesive residue tends to remain, or productivity during printing tends to be reduced.

  Since the adhesive layer of the heat-sensitive label of the present invention is formed of the heat-sensitive adhesive having the above-described configuration, it has excellent adhesiveness and blocking resistance, and can quickly develop tackiness by heating. Can prevent glue residue on.

  The label substrate can be appropriately selected in consideration of heat resistance, handleability, printability, and the like. Plastic film, plastic sheet; paper having water resistance such as coated paper, Japanese paper, synthetic paper, etc .; aluminum foil, etc. Metal foil; Nonwoven fabrics and composites thereof can be used. Among these, a plastic film is preferable from the viewpoint of physical properties such as strength and handleability. 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, acrylic A film made of a resin such as These may be used singly or in combination of two or more, copolymerized or laminated.

  The thermal contraction rate of the label base material varies depending on the type of label and is not particularly limited. However, when a non-heat-shrinkable film is used as the label base material, MD is immersed in hot water at 90 ° C. for 5 seconds. Both the direction and the TD direction 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. Moreover, 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 the thermal shrinkage rate, for example, 10 to 60% in the MD direction and about −3 to 20% in the TD direction are immersed in hot water at 90 ° C. for 10 seconds.

  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, after using the container equipped with the label, it can be easily separated from the container main body (or a pulverized product thereof) by utilizing the specific gravity difference, and the label and the container main body can be easily recycled. At this time, it is preferable to use hot alkaline water because the label can be peeled and separated at the same time. The heat-sensitive label of the present invention is particularly excellent in adhesion to polypropylene because the adhesive layer is formed of the emulsion-type heat-sensitive adhesive having the above structure. For this reason, when the thermal label is wrapped around the side body of the bottle, excellent adhesion is achieved when the adhesive layer surface of the other end is overlapped with the base material surface of one end of the thermal label and bonded by heating. Can be attached and fixed.

  For example, a non-shrinkable unstretched film or a biaxially stretched film can be used as a label base material for a label that is wound around a container. Among them, a non-shrinkable polypropylene film, particularly a biaxially stretched polypropylene film (OPP) is preferably 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. These materials can be used alone or in admixture of two or more. The label substrate may be a single layer or a laminate of two or more layers.

  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 printing layer can be formed by printing a desired image and characters on at least one surface of the label base material by a conventional printing method such as gravure printing or flexographic printing. The thickness of the printing layer is not particularly limited and is, for example, about 0.1 to 10 μm.

  The heat-sensitive label of the present invention may have at least one adhesive layer and one printed layer. Further, the adhesive layer and the printing layer may be provided on the entire surface of the label base material, or may be provided on a part of the label base material. Among them, the adhesive layer is formed in a strip shape in the longitudinal direction (the height direction of the cylindrical label) on the entire surface, or in the width direction (the circumferential direction of the cylindrical label) after the label processing. 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 cylindrical shape that is superposed on and bonded together.

  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. Especially, when a base material is an olefin type, it is preferable that an adhesive bond layer is directly provided in a base material. In particular, a label having a layer structure of a printing layer / label substrate / adhesive layer in which a printing layer and an adhesive layer are laminated on both sides of a label substrate is preferably used. However, from the viewpoint of exhibiting the effects of the present invention, the heat-sensitive label has a layer structure 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. Note that the overcoat layer is preferably formed so as to avoid a region in contact with the adhesive layer. 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 printing layer, the adhesive layer and the primer coat layer, and the overcoat layer. A layer of non-woven fabric, paper, plastic, etc. may be provided as necessary.

  The total thickness of the thermosensitive label of the present invention is, for example, 6 to 75 μm, preferably 8 to 60 μm, in terms of cost and appearance. In particular, the label tends to be thin because it gives a sense of unity with the container at the time of sticking and is excellent in decorating properties. However, if the thickness is too thin, the workability and workability at the time of sticking are inferior.

  The heat-sensitive label of the present invention has good adhesiveness. 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. The sample can be evaluated as an adhesive strength to the container surface or an adhesive strength to the label substrate by a test according to JIS K 6854-3 (T-type peeling) (details are according to the test method described later). . The adhesive strength of the adhesive layer based on the above method to the plastic sheet is, for example, 0.7 to 5 N / 15 mm, preferably 0.7 to 3.5 N / 15 mm. When the adhesive strength is less than 0.7 N / 15 mm, a mounting defect such as the inability to adhere the heat-sensitive label to the container tends to occur. In addition, the adhesive residue preventing property is observed by visually observing the presence or absence of adhesive residue on the plastic sheet after affixing and peeling the label according to the T-type peel test using the same material and physical properties as the container surface. Can be evaluated.

The heat-sensitive label of the present invention has good blocking resistance. The anti-blocking property of the thermosensitive label in the present invention is such that, for example, the thermosensitive label is stacked so that the label substrate and the adhesive layer are in contact with each other, and a weight of 100 g / cm ³ is placed on the thermosensitive label for 24 hours in an atmosphere of 40 ° C. Then, it can be evaluated by a method of visually observing the presence or absence of blocking when peeling by hand. According to the heat-sensitive label of the present invention, the adhesive layer surface has little or no stickiness, and can exhibit excellent blocking resistance. The blocking resistance can be adjusted mainly by the melting point of the olefin resin, the type and content of the tackifier and acrylic resin, and the like.

  Furthermore, the heat-sensitive label of the present invention can maintain the adhesive force for a certain time after heat activation (the open time is long). Thus, the thermal label which has delay property is advantageous at the point which can improve sticking workability | operativity. Specifically, for example, even when a heat-sensitive label is heated at a temperature of 100 ° C. for 5 seconds and left at room temperature for about 5 seconds and then bonded to an adherend, sufficient adhesive strength (for example, JIS K 6854-3 ( Adhesive strength in conformity with T-type peeling) can be applied to an adherend with 0.7 N / 15 mm or more.

  The adhesive residue deterrence can be adjusted mainly by the molecular weight and content of the acrylic resin, and can be adjusted by the type of the olefin resin and the type and content of the tackifier. Usually, when a solid plasticizer is added to give delayed tackiness, an adhesive residue is likely to be generated. According to the present invention, the adhesive layer contains an acrylic resin and an olefin resin as a base polymer. By controlling the cohesive force of the layer, it is possible to achieve both delayed tack and adhesive residue inhibiting properties. Therefore, adhesive strength can be suppressed by improving the film strength while maintaining excellent workability and sufficient adhesive force.

  Moreover, the heat-sensitive label of the present invention has alkali peelability. Here, the alkali releasability means a characteristic that the heat-sensitive label is peeled from the surface of the adherend by immersing it in an alkali solution in a heat-sensitive label attached to the adherend and dissolving the adhesive. The heat-sensitive label of the present invention can be easily peeled 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 the adhesive layer side 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 an olefin 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.

  The adherend is, for example, a soft drink bottle such as a PET bottle, a milk bottle for home delivery, a food container such as a seasoning, a bottle for alcoholic beverages, a pharmaceutical container, a detergent container, a chemical container such as a spray, cup noodles, etc. Containers such as containers are included. The shape of the container 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 an olefin resin such as high density polyethylene or polypropylene is preferable, and a polyester resin container is particularly preferable.

The labeled container of the present invention is a labeled container in which the thermosensitive label of the present invention is attached to a container made of a polyester resin or an olefin resin, and the label substrate constituting the thermosensitive label is a polyester resin or an olefin Resin. Especially, the structure by which the thermosensitive label which consists of a label base material of an olefin resin was mounted | worn with the container consisting of a polyester-type resin is preferable.

  The container shape includes, for example, a bottom portion, a trunk portion that is connected upward from the bottom portion, a shoulder portion that is positioned above the trunk portion and has a diameter that is reduced upward, and a mouth portion that is located above the shoulder portion. Have. The spout has a spout through which the contents can be put in and out, and the cap is screwed so that the spout can be closed. The cross-sectional shape of the container body is exemplified by polygons such as a circle, an ellipse, a quadrangle, a hexagon, and an octagon, and is not particularly limited. Although the manufacturing method of a container is not specifically limited, It is produced by blow molding, injection molding, and sheet molding. The material of the container is not particularly limited as long as it is a polyester resin or an olefin resin, but a polyester resin is preferable, and a polyethylene terephthalate resin is particularly preferable.

FIG. 1 is a schematic cross-sectional view showing an example of a thermosensitive label attached to the labeled container of the present invention. The thermosensitive label 1 shown in FIG. 1 has a rectangular shape in which adhesive layers 3 a and 3 b are provided at both ends of a label base 2. That is, the first adhesive layer 3a is directly laminated on the inner surface of the label base material 2 at one end X, and is laminated on the label base material via the printing layer 4 on the inner surface of the label base material at the other end Y. The second adhesive layer 3b is formed. The print layer 4 is provided on the same surface as the adhesive layers 3a and 3b of the label base 2 on the entire surface excluding one end. In the present invention, the printing layer does not need to be provided on the entire surface excluding the one end portion X, and may be partially formed according to a desired design. Moreover, the printing layer 4 does not need to be provided in the other end part Y, and a part or all of the 2nd adhesive bond layer 3b may be directly laminated | stacked on the label base material 2 without going through a printing layer. .

  The adhesive layer (the first adhesive layer 3a and the second adhesive layer 3b) is an emulsion-type heat-sensitive material containing a base polymer composed of the above-mentioned acrylic resin and olefin resin, a solid plasticizer, and a tackifier. It can be formed using an adhesive. The emulsion-type heat-sensitive adhesive used for the first adhesive layer 3a and the second adhesive layer 3b may be the same or different, but from the viewpoint of label productivity, the same adhesive is used. It is often done. The adhesive layers 3a and 3b constituting the heat-sensitive label that is wound around the side body of a 500 ml bottle-like container are, for example, 5 to 5 from the respective edges at the one end X and the other end Y of the label. It is provided in a strip shape with a width of about 30 mm across the upper and lower edges.

  The material of the label substrate 2 used in the labeled container of the present invention is not particularly limited as long as it is a polyester resin or an olefin resin, but when the container is made of a polyester resin, it may be an olefin resin. A polypropylene resin is particularly preferable.

  The label can be attached to the container by, for example, putting the surface of the heat-sensitive label on the adhesive layer side on the surface of the container and pressing a hot plate from the label substrate side, or sucking the heat-sensitive label from the label substrate side to the heating drum. 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 (labeler temperature) is appropriately selected according to the activation temperature of the adhesive layer, and is preferably, for example, 70 to 150 ° C, more preferably 80 to 120 ° C.

2A is a perspective view showing an example of the labeled container of the present invention, FIG. 2B is a sectional view taken along the line ZZ of FIG. 2A, and FIG. An enlarged view is shown. In the labeled container of the present invention, one end portion X of the thermosensitive label 1 is attached to the container 5, the thermosensitive label 1 is wound around the container 5, and the other end portion Y is overlapped and attached to the one end portion X. Yes. Specifically, it is a labeled container in which the thermosensitive label 1 is wound around the body portion of the container 5, and one end X and the other end Y of the label 1 are overlapped to form a superposed portion W, and heat sensitive One end X of the label 1 is bonded to the body of the container 5 by a first adhesive layer 3a provided on the inner surface of the label substrate 2, and the other end Y is one end by a second adhesive layer 3b. It is directly bonded to the outer surface of the label substrate 2 of X.

  The heat-sensitive label of the present invention uses a base polymer composed of an acrylic resin and an olefin resin as an adhesive layer, thereby exhibiting sufficient adhesion to the adherend surface and the label substrate. It can be fixed on the body surface, and the adhesive layer has a large cohesive force, so that adhesive residue can be suppressed. The container with a label of the present invention can be peeled off without being left on the surface of the adherend (container) by being immersed in an alkali (for example, alkaline hot water of about 85 ° C.) after use. Therefore, the container with a label of the present invention can be separated and collected by a simple method after use in a normal recycling facility.

In the labeled container of the present invention, the adhesive layer (first adhesive layer 3a, second adhesive layer 3b) exhibits good adhesion to a polyester-based resin or a polypropylene-based resin. The part pasted on can be prevented from being inadvertently peeled off. In particular, in the case of a labeled container in which a heat-sensitive label made of an olefin-based resin label is attached to a container made of a polyester-based resin, adhesive residue on the surface of the container can be remarkably suppressed. By utilizing the difference in specific gravity, the container main body (or pulverized product thereof) can be easily separated, and the label and the container main body can be easily recycled. Furthermore, in the configuration in which the first adhesive layer 3a is directly laminated on the label substrate, the adhesive used in the present invention has excellent adhesion to the label substrate made of an olefin resin (propylene resin). Therefore, the adhesive residue on the container surface can be more effectively suppressed.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Table 1 shows the blending amounts (contents) of the components of Examples and Comparative Examples, evaluation results, and the like. In the table, the blending amounts of acrylic resin, olefin resin, tackifier, and solid plasticizer are all expressed in parts by weight of the solid content of each component.

Examples 1-8, Comparative Examples 1-2
Collect the acrylic emulsion, olefin emulsion, solid plasticizer, and tackifier listed in Table 1 in a plastic beaker and mix using a high-speed disperser (trade name “TK Homomixer”, manufactured by Primics). By stirring, emulsion-type heat-sensitive adhesives each having physical property values shown in Table 1 were obtained. The solid plasticizer used in advance was pulverized and dispersed to a mean particle size of 20 μm or less by a bead mill.
Each emulsion-type heat-sensitive adhesive obtained was dried using a wire bar (WB) on one side of a biaxially stretched polypropylene film [OPP film: Toray Industries, trade name “Trephan”, thickness 40 μm]. It was applied to a thickness of 7 μm and dried at room temperature for 3 minutes to obtain a thermosensitive label. The constituent components of the adhesive shown in Table 1 are shown below together with the physical property values.
Using the obtained thermosensitive label, one end of the label is placed on the surface of a PET bottle (Toyo Seikan) and the adhesive layer is activated and pressed by pressing a hot plate from the label substrate side, and then the thermosensitive label is bottled. Then, the other end portion was overlapped with the one end portion, and the adhesive layer was activated by pressing the hot plate from the label base material side to obtain a labeled container.
(Composition of heat-sensitive adhesive)
Acrylic base polymer: “New Coat K-2” Tg-26 ° C
Acrylic base polymer: "Polytron Z130" Tg-56 ° C
Olefin base polymer: “Aurolen AE-301” Tm60-70 ° C.
Olefin base polymer: “Hardren NZ-1000” Tm 70 ° C.
Solid plasticizer: DCHP Tm 66 ° C
Tackifier: “Nanolet R-1050” Softening point 105 ° C.

(Evaluation test)
Adhesive strength [vs OPP, v PET]
A test piece having a width of 15 mm was prepared from the labels obtained in Examples and Comparative Examples, and the surface of the test piece on the side of the adhesive layer was coated with an OPP sheet (similar to the label substrate) and PET made by Toyo Seikan. Polyethylene terephthalate sheet made of the same material as the bottle [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), Samples pressure-bonded with a hot plate under the conditions of a temperature of 100 ° C., a pressure of 0.1 MPa, and a time of 1 second, using a tensile tester (manufactured by Shimadzu Corporation, trade name “Autograph”) according to JIS K 6854-3 The T-type peel test (peeling speed 300 mm / min) was performed by the above method, and the adhesive strength (N / 15 mm) of the label was measured.

Blocking resistance Two test pieces prepared by the same method as in the evaluation of the adhesive strength were stacked so that the label substrate and the adhesive layer were in contact with each other, and a 100 g / cm ³ weight was placed on the atmosphere at a temperature of 40 ° C. When stored under the test for 24 hours, the state when the stacked test pieces were peeled off by hand was visually observed. When no blocking was observed, “○”, when blocking occurred and the samples were difficult to peel off Was evaluated as “×”.

Open time A test piece having a width of 15 mm was prepared from the labels obtained in the examples and comparative examples, and the surface of the test piece on the adhesive layer side was heated at a temperature of 100 ° C. for 5 seconds and then left at room temperature for 5 seconds to obtain PET. Sheet (similar to that used for evaluation of adhesive strength) was pressed with a heat sealer under the conditions of adhesive area: 10 mm (peeling direction) × 15 mm (width direction), normal temperature, pressure 0.1 MPa, time 1 second. Using a tensile tester (manufactured by Shimadzu Corporation, trade name “Autograph”), a sample was subjected to a T-type peel test (peel rate 300 mm / min) according to JIS K 6854-3, and the adhesive strength of the label ( N / 15 mm).

Adhesive residue deterrence For the labels obtained in Examples and Comparative Examples, when the adhesive strength was measured, the presence or absence of adhesive residue on the surface of the PET sheet was visually observed, and no adhesive residue was found on the PET sheet surface. Was evaluated as “X” when the adhesive residue was observed.

Alkali peelability A sample having the same structure as the sample prepared for the evaluation of the adhesive strength was immersed in a sodium hydroxide aqueous solution (alkali solution) having a temperature of 90 ° C. and a concentration of 1.5% by weight for 15 minutes with stirring. When the label and the PET sheet were completely peeled off in the alkaline solution, “◯” was evaluated, and when the label, the adhesive, and the PET sheet were even partially adhered, “×” was evaluated. .

It is a schematic sectional drawing which shows an example of the thermosensitive label of this invention. (A) is a perspective view which shows an example of the container with a label of this invention, (B) is ZZ sectional drawing of (A), (C) is an enlarged view of the label superposition | polymerization part W. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal label 2 Label base material 3 Adhesive layer
3a First adhesive layer
3b Second adhesive layer 4 Print layer 5 Container W Overlapping part of label end X One end of label Y The other end of label Z Cross-sectional position

Claims (6)

A heat-sensitive label in which an adhesive layer and a printing layer are laminated on a label base material, the adhesive layer comprising a base polymer composed of an acrylic resin and an olefin resin, a solid plasticizer, and a tackifier And the mixing ratio of the acrylic resin and the olefin resin constituting the base polymer is the former / the latter (weight ratio in terms of solid content) = 20 / 80-80. / 20, the acrylic resin has a glass transition temperature of −60 ° C. to 40 ° C., and the olefin resin is an olefin resin selected from an acid-modified olefin resin and a halogenated olefin resin. . Thermal label of claim 1, wherein the melting point of the olefin resin is 30 to 140 ° C.. The heat-sensitive label according to claim 1 or 2, wherein the olefin resin is a polypropylene resin. The thermosensitive label according to any one of claims 1 to 3 , wherein the thermosensitive label is a container with a label attached to a container made of a polyester resin or an olefin resin, and the label substrate constituting the thermosensitive label is a polyester resin or Labeled container that is an olefin resin. The labeled container according to claim 4, wherein the container is made of a polyester-based resin, and the label base material constituting the heat-sensitive label is an olefin-based resin. 6. A label according to claim 4 or 5, wherein one end of the label is attached to the container, the label is wound around the container, and the other end is overlapped and attached to the surface of the label base material on the one end. container.

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