JP2007171239A - Heat-sensitive label and labeled container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sensitive label attaining adhesiveness, blocking resistance, and a property of suppressing paste remaining and, in addition, which is excellent in workability in attaching because of its good delayed property, and to provide a labeled container with the label attached thereto. <P>SOLUTION: The heat-sensitive label 1 is composed of a label base material 2 on which an adhesive layer 4 and a printing layer 3 are laminated. The adhesive layer comprises: an ethylene-based copolymer whose ethylene content is 66-90 wt.%; a main agent composed of an adhesion imparting agent and a solid plasticizer; and a delayed type heat-sensitive adhesive which contains 10-50 pts.wt. of auxiliary substance of urethane-based resin whose weight average molecular weight is 20,000-300,000 to 100 pts.wt. of the main agent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thermal label attached to a container or the like, and more particularly to a thermal label using a delayed thermal adhesive. The present invention also relates to a container equipped with the label.

  Conventionally, a tack label is often used as a label to be attached to a polyethylene terephthalate container (so-called PET bottle), a plastic container such as polypropylene or polyethylene, or a glass bottle, but the label has a tack property even at room temperature. Release paper for protecting the pressure-sensitive adhesive layer is necessary until it is attached to the container, which has problems in terms of environment such as cost, work efficiency, and industrial waste after use. Therefore, in recent years, as a label that does not require such a release paper, a heat-sensitive label that has no adhesive strength at room temperature and exhibits adhesiveness by heating has been used. As an adhesive (heat-sensitive adhesive) used for the heat-sensitive label, a delayed type heat-sensitive adhesive containing a thermoplastic resin, a tackifier, and a solid plasticizer is often used.

  The heat-sensitive label and heat-sensitive adhesive are required to have a property of firmly bonding to a container or the like so that troubles such as label peeling do not occur when the container is used. However, on the other hand, from the viewpoint of recycling and the like, the label can be easily peeled 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, thermosensitive adhesives are required to have conflicting characteristics such as high adhesiveness, easy peelability, and suppression of adhesive residue.

  As a heat-sensitive label having easy peelability and hardly causing adhesive residue, an easily peelable heat-sensitive label made of a heat-sensitive resin to which a tackifier is added is known (for example, see Patent Document 1). However, since this heat-sensitive adhesive layer is formed by melt extrusion, a labeling process requires a melt coating process, which is disadvantageous in terms of cost and productivity, and difficult to apply to a thin film. Since the pressure-sensitive adhesive layer to be formed is relatively thick, there are problems such as poor integration with the container and reduced decorativeness.

  In addition, it is a label that directly adheres one end of the label to the bottle and the other end to one end of the label (label surface). There is known a container label that uses an adhesive having an excellent adhesive force at the other end that adheres to the container to achieve both adhesiveness and easy peelability (see, for example, Patent Document 2). However, in this case, in the label manufacturing process, it is necessary to apply two different types of adhesives to the film with high accuracy, which is disadvantageous in terms of 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 2004-85651 A JP 2004-219621 A

  In order to solve the above-mentioned problems, an emulsion-type heat-sensitive adhesive in which a specific amount of an auxiliary agent composed of an acrylic resin or a polyurethane resin is blended with a main component composed of an ethylene-based copolymer and a tackifier is developed. In the case of a delayed heat-sensitive adhesive with an increased solid plasticizer content for the purpose of improving workability, the adhesive strength is increased and adhesive residue is generated again. A heat-sensitive adhesive that satisfies all requirements such as performance and workability has not been obtained.

  That is, the object of the present invention is to have excellent adhesiveness and anti-blocking property, and hardly cause adhesive residue on the container when the label is peeled off. It is an object of the present invention to provide a thermosensitive label that can cope with an increase in speed and a container equipped with the label.

  As a result of intensive studies to solve the above problems, the present inventors have used an emulsion-type heat-sensitive adhesive having a specific amount of a solid plasticizer and a specific urethane resin, so that excellent adhesiveness and blocking resistance, easy It has been found that a heat-sensitive label that achieves releasability and suppression of adhesive residue at the time of peeling and is excellent in workability due to delay properties can be obtained at low cost, and the present invention has been completed.

  That is, the present invention is a label in which an adhesive layer and a printing layer are laminated on a label base material, and the adhesive layer is an ethylene copolymer, an adhesive having an ethylene content of 66 to 90% by weight. A main agent composed of an imparting agent and a solid plasticizer, and a delayed thermosensitive adhesive containing 10 to 50 parts by weight of an auxiliary agent which is a urethane resin having a weight average molecular weight of 20000 to 300,000 with respect to 100 parts by weight of the main agent. Providing featured thermal labels.

  Furthermore, the present invention provides the above heat-sensitive label, wherein the urethane-based resin has a minimum film forming temperature (MFT) of less than 40 ° C.

  Furthermore, the present invention provides the heat-sensitive label, wherein the printing layer is made of urethane ink.

  Furthermore, this invention provides the container with a label with which the said thermosensitive label was mounted | worn.

  The heat-sensitive label of the present invention can be easily peeled off without being left 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, workability is good because the adhesive strength is maintained for a certain period of time after activation by heating. Therefore, it is particularly useful as a heat-sensitive label used for PET bottles and the like.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of the thermal label of the present invention. In the thermosensitive label 1 shown in FIG. 1, a printing layer 3 and an adhesive layer 4 are laminated on one side of a label substrate 2.

  The heat-sensitive label of the present invention is formed by laminating an adhesive layer and a printing layer on a label substrate. The adhesive layer and the printing layer may have at least one layer each. Further, the adhesive layer and the printing layer do not need to be provided on the entire surface of the label base material, and 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 preferably provided. 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 rolled, 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). 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, Stacked configurations may be combined. Furthermore, the printing layer and the adhesive layer may be separately provided on the front and back of the base material layer (printing layer / label base material / adhesive layer). However, from the viewpoint of exhibiting the effect of the present invention, it is preferable that the heat-sensitive label includes at least a portion where the adhesive layer becomes the outermost layer. If there is no portion where the adhesive layer is the outermost layer, it is difficult to exert the effects of the present invention.

  The label substrate used in the heat-sensitive label of the present invention can be appropriately selected in consideration of heat resistance, handleability, printability, and the like. Plastic film, plastic sheet; coated paper and other water-resistant paper, Japanese paper, synthetic paper Paper such as 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, acrylic A film made of a resin such as These may be used singly or in combination of two or more.

  The plastic film 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, you may use any of an unstretched film, a uniaxially oriented film, and a biaxially oriented film according to a required physical property, a use, etc.

  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. As the heat-shrinkable film, a polyester resin, a polystyrene resin, a polyvinyl chloride resin, particularly a film made of a polyester resin is preferably used.

  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, but is preferably less than 5% in both the MD direction and the TD direction, more preferably 1 under the condition of immersion in hot water at 90 ° C. for 5 seconds. %. 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. In particular, when a non-heat-shrinkable film is used as the label base material, the heat shrinkage rate (MD, TD direction) is preferably 5% or less, more preferably 5 seconds or less under the condition of immersing in a 100 ° C. glycerin bath for 5 seconds. 1% or less.

  The adhesive layer of the heat-sensitive label of the present invention comprises a delayed heat-sensitive adhesive. The delayed (delay tack: delayed tack) type heat-sensitive adhesive is an adhesive having a delay property that is activated by heat and exhibits tack, and maintains tack for a certain period of time. At normal temperature, there is almost no tack and no problems such as blocking occur. Therefore, release paper is unnecessary, which is preferable from the viewpoints of environment and handling. Moreover, since the adhesiveness is maintained for a long time after heating, it is easy to handle in the label mounting process and the like, and the workability and productivity are improved. In the case of an adhesive which does not have a delay property such as a hot melt type, since it is necessary to attach a label immediately after heating, manufacturing is difficult and workability and productivity may be reduced.

  The delayed heat-sensitive adhesive of the present invention contains a main agent composed of an ethylene copolymer, a tackifier and a solid plasticizer, and an auxiliary agent composed of a urethane resin as essential components. In the heat-sensitive adhesive, the main agent plays a role of tackiness and adhesiveness development, and the auxiliary agent mainly plays a role of increasing the cohesive force of the adhesive layer to express easy peeling and preventing adhesive residue. In addition, the solid plasticizer in the main agent plays a role of adjusting the solidification rate of the adhesive and imparting delay properties. Further, in addition to the above, various additives may be contained as required. Examples of the additives include emulsifiers, waxes, modifiers, pigments, dyes, lubricants, antioxidants, ultraviolet absorption. Agent, antistatic agent, fluorescent whitening agent, anti-blocking agent, flame retardant, foaming agent, reinforcing agent, filler, leveling regulator, thickener, antifoaming agent, surfactant, antifungal agent, neutralizing agent , Fragrances, antifreezing agents, crosslinking agents, deodorants, stabilizers and the like.

  The delayed heat-sensitive adhesive of the present invention is not particularly limited, but is used in the form of an emulsion in which the above-mentioned main agent, auxiliary agent and other additives are dispersed in water by a conventional method. The (aqueous) emulsion-type heat-sensitive adhesive dispersed in water can be prepared, for example, by emulsion polymerization of a monomer containing ethylene corresponding to the ethylene-based polymer.

  The ethylene copolymer used for the delayed heat-sensitive adhesive of the present invention is an ethylene copolymer containing 66 to 90% by weight of an ethylene component in the copolymer. When the ethylene component content is out of the above range, tackiness is lowered. Examples of the ethylene copolymer include ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), and ethylene-acrylic acid. Examples thereof include ethylene-acrylic acid ester copolymers such as ethyl copolymer (EEA) and ethylene-methacrylic acid ester copolymers such as ethylene-methyl methacrylate copolymer (EMMA). Of these, EVA copolymers are preferably used. These can be used alone or in combination of two or more.

  The glass transition temperature (Tg) of the ethylene copolymer of the present invention is preferably about −30 to 70 ° C. from the viewpoints of adhesiveness and blocking resistance. When the glass transition temperature is less than −30 ° C., the blocking resistance may be lowered, and when it exceeds 70 ° C., the adhesive force may be lowered.

  The tackifier used in the delayed heat-sensitive adhesive of the present invention has an effect of improving adhesiveness. For example, a rosin resin (rosin, polymerized rosin, hydrogenated rosin and derivatives thereof, resin acid dimer, etc.), Terpene resin (terpene resin, aromatic modified terpene resin, hydrogenated terpene resin, terpene-phenol resin, etc.), petroleum resin (aliphatic, aromatic, alicyclic), coumarone-indene resin, styrene resin And phenol resin. A tackifier can be used individually or in combination of 2 or more types.

  The tackifier of the present invention is also available on the market, and examples thereof include “YS Polyster” manufactured by Yashara Chemical Co., Ltd. and “Pine Crystal” manufactured by Arakawa Chemical Co., Ltd.

  In the total solid content of the main agent used in the delayed heat-sensitive adhesive of the present invention, the content of the ethylene copolymer is preferably 10 to 40% by weight, more preferably 15 to 40% by weight. Further, the content of the tackifier is preferably 1 to 20% by weight, more preferably 1 to 15% by weight. When the content of the tackifier exceeds 20% by weight, an adhesive residue may easily occur.

  The solid plasticizer used in the delayed heat-sensitive adhesive of the present invention is non-tacky at room temperature, but has a role of melting by heating and plasticizing the main resin to develop tackiness. As such a solid plasticizer, a known solid plasticizer can be used. Phthalate ester compounds such as diphenyl phthalate, dihexyl phthalate and dicyclohexyl phthalate; phosphate ester compounds, hindered phenols It can be selected from compounds, triazole compounds, hydroquinone compounds and the like.

  The content of the solid plasticizer of the present invention is preferably 40 to 80% by weight in the total solid content of the main agent. When the content of the solid plasticizer is less than 40% by weight, the delayed tackiness may be insufficient and workability may be reduced. On the other hand, if the content exceeds 80% by weight, the cohesive force may be reduced, resulting in an adhesive residue.

  In the delayed heat-sensitive adhesive of the present invention, a urethane resin is used as an auxiliary agent. The weight average molecular weight (Mw) of the urethane-based resin used in the present invention is 20000 to 300,000, preferably 50,000 to 200,000. In the present invention, the urethane-based resin has an effect of increasing the cohesive force of the adhesive layer and suppressing adhesive residue. Generally, the higher the molecular weight of the urethane resin, the higher the cohesive force of the adhesive layer. However, it has been found that when the molecular weight of the urethane-based resin becomes too high, the effect of increasing the cohesive force is reduced. In the heat-sensitive adhesive of the present invention, when the weight-average molecular weight of the urethane-based resin is less than 20,000, the cohesive force of the adhesive layer is reduced and adhesive residue tends to be generated, and the weight-average molecular weight is 300000. Even in the case of exceeding, adhesive residue tends to occur.

  In particular, the urethane-based resin of the present invention preferably has a minimum film-forming temperature (MFT) of less than 40 ° C, particularly preferably less than 20 ° C. A urethane-based resin having an MFT satisfying the above range is preferable because it provides a good cohesive force under the use temperature condition of the adhesive of the present invention. When the MFT exceeds 40 ° C., the cohesive force is insufficient at the use temperature of the adhesive, and adhesive residue may be generated.

  The urethane-based resin of the present invention is not particularly limited as long as it satisfies the above conditions, but an aliphatic urethane resin is preferable because it can be used without yellowing. When an aromatic urethane resin is used, yellowing may occur during storage.

  Such urethane-based resins are also available on the market, and examples thereof include “FW413” manufactured by Nippon Kakko Paint Co., Ltd., “Hydran AP-20” manufactured by Dainippon Ink and Chemicals, Inc., and the like.

  Content of the adjuvant (solid content) of this invention is 10-50 weight part with respect to 100 weight part of main ingredient solid content, Preferably it is 15-40 weight part. When the content of the auxiliary agent is less than 10 parts by weight, adhesive residue tends to occur. Moreover, when it exceeds 50 weight part, adhesive force and blocking resistance will fall, and it will become easy to produce troubles, such as a productivity fall and peeling of a label.

  The thickness of the adhesive layer of the present invention may be appropriately selected in consideration of adhesiveness, appearance, cost and the like, and is not particularly limited, but is preferably 0.1 to 10 μm, more preferably 1 to 5 μm. When the thickness of the adhesive layer is greater than 10 μm, cohesive failure may occur and the adhesive strength may decrease, and when it is less than 0.1 μm, the adhesiveness may decrease. In addition, although the thickness of the said adhesive bond layer is not specifically limited, For example, it can measure with a three-dimensional microscope etc.

  The adhesive layer of the heat-sensitive label of the present invention is preferable because an emulsion-type heat-sensitive adhesive is particularly excellent in labeling when an emulsion-type heat-sensitive adhesive is used as a constituent adhesive. Emulsion-type heat-sensitive adhesives are dispersions in which polymer components (solid content) are dispersed in the form of particles in a liquid, so that the coated surface of the adhesive forms minute irregularities due to the particles to prevent blocking. The efficiency of the sticking work by the labeler can be improved. The labeling suitability can be evaluated by a static friction coefficient between the label base material and the adhesive layer by a test according to JIS K 7125, and the static friction coefficient between the label base material and the adhesive layer is less than 0.5. Is preferred. When the static friction coefficient is 0.5 or more, the overlapping labels are difficult to slip, and the labeler suitability may be reduced.

  The printing layer used in the thermal label of the present invention is a layer displaying a product name, an illustration, handling precautions, etc., and is formed by a conventional printing method such as letterpress printing, silk screen printing, gravure printing, flexographic printing, and the like. be able to. 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. Among these, from the viewpoint of adhesion with the heat-sensitive adhesive layer, a printing layer made of urethane ink is particularly preferable. The thickness of the printing layer is not particularly limited and is, for example, about 0.1 to 10 μm.

  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, 0.3-1.5 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. Although the thickness of an overcoat layer is not specifically limited, 0.5-2 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 tackiness. Tackiness is determined by a test according to JIS K 6854-3 (T-type peeling) for a sample in which a label activated by heating to 90 ° C. is adhered to a plastic sheet similar to the container surface (peeling speed 200 mm). / Min), which can be evaluated as the adhesive strength to the container surface (details are based on the test method described later). The adhesive strength of the adhesive layer based on the above method to the plastic is preferably 1 N / 15 mm or more (for example, 1 to 5 N / 15 mm), more preferably 1 to 3 N / 15 mm. When the adhesive strength is less than 1 N / 15 mm, mounting defects such as inability to adhere the thermosensitive label to the container are likely to occur.

The heat-sensitive label of the present invention has good blocking resistance. Here, the blocking resistance means that the surface of the label on the adhesive layer side and the surface of the label base material are overlapped and a pressure of about ² kg / cm ² (196 kPa) is applied, and the pressure is 24 under an atmosphere of 40 ° C. About the sample stored for a long time, it can evaluate as adhesive strength with respect to plastic by the test according to JISK6854-3 (T-type peeling) (peeling speed 200mm / min) (details are based on the below-mentioned test method). The adhesive strength of the adhesive layer based on the above method to the plastic is preferably less than 0.2 N / 15 mm. When the adhesive strength is 0.2 N / 15 mm or more, tackiness is likely to occur when the labels are wound or stacked, and the labeling suitability during labeling is poor. The blocking resistance can be adjusted mainly by the melting point of the ethylene copolymer, the kind and content of the tackifier and the auxiliary agent, and the like. Further, the urethane resin of the present invention tends to cause blocking when the content is large.

  The heat-sensitive label of the present invention has good adhesive residue deterrence. The adhesive residue deterrence here refers to, for example, the surface of a plastic sheet when a label after a predetermined period of time has elapsed (for example, after one week) is peeled off in the same manner as the method for measuring the tackiness strength. It can be evaluated by a method of visually observing whether or not there is any adhesive residue, or a method of visually observing the presence or absence of adhesive residue when the label is peeled off from the PET bottle on which the label is actually attached. The adhesive residue deterrence can be adjusted mainly by the molecular weight and content of the urethane resin as an auxiliary agent, and can be adjusted by the type of ethylene copolymer and the type and content of tackifier. . Usually, when a solid plasticizer is added to give delayed tackiness, adhesive residue tends to be generated. However, according to the present invention, the adhesive layer contains a predetermined auxiliary agent to control the cohesive force of the adhesive layer. This makes it possible to achieve both delayed tack and adhesive residue deterrence. Therefore, adhesive strength can be suppressed by improving the film strength while maintaining excellent workability and sufficient adhesive force.

  The heat-sensitive adhesive used for the heat-sensitive label of the present invention has both adhesiveness, easy peelability and adhesive residue deterrence, so that one end of the label is directly bonded to the bottle and the other end is on the front end portion of the label (label surface ) When used as a wrapping label that adheres to the bottle, the adhesive used on the side that adheres to the surface of the label (excellent adhesiveness and adhesive residue deterrence required) Can be used as both adhesives that require high adhesiveness and easy peelability. 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.

  In the labeled container of the present invention, the thermosensitive label of the present invention is mounted so that the adhesive layer side is in contact with the container. The thermosensitive label may be attached to the entire surface of the container or may be attached to a part thereof. The material of the container is not particularly limited and may be any of plastic, glass, metal, etc., but a plastic container made of polyester such as polyethylene terephthalate, high density polyethylene, polypropylene, or the like is preferable. Such containers include, for example, soft drink bottles such as PET bottles, milk bottles for home delivery, food containers such as seasonings, bottles for alcoholic beverages, pharmaceutical containers, detergents, and containers for chemical products such as sprays. , Cup noodle containers and the like. The shape of the container includes various shapes such as a cylindrical shape, a square bottle, and a cup type. Further, the material of the container includes plastic such as PET, glass, metal and the like.

  Below, the manufacturing method of the thermosensitive label of this invention and the labeled container which mounted | wore with this label is demonstrated. The production method of the present invention is not limited to this.

[Label substrate]
As a label base material used for the thermosensitive label of the present invention, a plastic film will be described as an example.

  Resins used as raw materials for plastic films (for example, polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, etc.) can be polymerized using known techniques. For example, polyester is obtained by using a process in which terephthalic acid and ethylene glycol are used as raw materials, a low molecular weight polyethylene terephthalate is obtained by a direct ester reaction, and a polymer is obtained by a polycondensation reaction using antimony trioxide as a catalyst. You may copolymerize 1, 4- cyclohexane dimethanol etc. as needed. Further, if necessary, other admixtures such as a lubricant, an antistatic agent, an antifogging agent and an antioxidant may be mixed.

  Next, the raw material is formed into a sheet by a known method such as melt film formation (calendar method, T-die method, tube method, etc.) or solution film formation, and subjected to stretching treatment as necessary. Stretching is performed using a tenter method, a tube method, a roll method, or the like, for example, at a temperature of about 70 to 230 ° C., and 2.0 to 8.0 times in one direction (for example, the longitudinal direction; MD direction), Preferably, it is about 3.5 to 5.5 times. In the case of biaxial stretching, it is further 2.0 to 8.0 times, preferably 3.5 to 5.5 times in the other direction (for example, transverse direction; TD direction). It is performed by stretching to a certain extent.

  These resins can also be obtained on the market. As a commercially available plastic film, for example, as a biaxially stretched polyethylene terephthalate film, “Lumirror” manufactured by Toray Industries, Inc., and as a biaxially stretched polypropylene film, “A1” manufactured by Gunze Co., Ltd., manufactured by Tosero Co., Ltd. “U-1” or the like can be used.

  In addition, the surface of the label base material may be subjected to a conventional surface treatment such as corona discharge treatment or in-line coating, if necessary.

[Thermal adhesive]
The heat-sensitive adhesive is prepared by dispersing other components such as a main agent (ethylene copolymer, tackifier and solid plasticizer), auxiliary agents and additives in water by a conventional method. In the case of a water-based emulsion type heat-sensitive adhesive dispersed in water, for example, it is prepared by emulsion polymerization of a monomer containing ethylene corresponding to an ethylene-based polymer.

[Thermal label]
An adhesive layer and a printing layer made of the heat-sensitive adhesive are formed on at least one surface of the label base material to produce a heat-sensitive label. In addition to the above, a layer such as an overcoat layer may be further provided as necessary.

  The printing layer can be formed by a conventional printing method such as letterpress printing, silk screen printing, gravure printing or flexographic printing. 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 adhesive layer can be formed by a known printing method such as flexographic printing or gravure printing. In particular, gravure printing is preferable because the printing speed is high, the coating amount is stable, and the printing layer and the adhesive layer can be formed in one step. For printing, the heat-sensitive adhesive having the above-described configuration may be used as it is, or methanol or the like may be added to promote drying after printing. When an emulsion-type heat-sensitive adhesive is used as the adhesive, it can be easily applied to the label substrate (printing layer) using the same process as printing, and there is no need for separate processes such as melt extrusion coating. This is economically advantageous. And since an adhesive bond layer can be formed thinly, it is advantageous to the thickness reduction of a label, and adhesive residue can also be suppressed.

  The label is slit into a predetermined width and wound into a roll shape, and a heat-sensitive label is obtained as a plurality of rolls.

[Container with label]
Finally, the thermosensitive label obtained above is cut, and then attached to a predetermined container to produce a labeled container. 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 substrate side, or the thermal label is sucked from the label substrate side to the heating drum. Usually, a labeler (automatic labeling machine: label sticker) is applied by activating the adhesive layer by applying heat to the adhesive layer with a heat source such as heat or infrared rays, and then applying it to the container by pressing. 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. Since the labeled container thus obtained can reduce the thickness of the heat-sensitive label, the label and the container produce a sense of unity and are excellent in appearance. In addition, the activation temperature of an adhesive bond layer here is temperature which produces the adhesive strength (based on the said JISK6854-3) of 0.1 N / 15mm or more.

[Methods for measuring physical properties and methods for evaluating effects]

(1) Minimum film-forming temperature (MFT) of urethane resin
Measurement was performed in accordance with ASTM D 2354 using a urethane-based resin (aqueous emulsion) as a sample and a minimum film-forming temperature measuring device manufactured by Tester Sangyo Co., Ltd. The sample was applied and dried on a drying plate (aluminum) with a temperature gradient, and the boundary line between the transparent film and the white powder was defined as the minimum film forming temperature (MFT).

(2) Weight average molecular weight It measured using "HLC-8220 GPC" by Tosoh Corporation.

(3) Tackiness Labels (surfaces on the adhesive layer side) obtained in Examples and Comparative Examples were obtained by using polyethylene terephthalate (PET) sheets [manufactured by Toyobo Co., Ltd., trade name “A1101”, 100 μm (non-treated surface). ] Was bonded with a hot plate so that the bonding area was 10 mm (peeling direction) × 15 mm (width direction) (temperature 90 ° C., pressure 0.1 MPa, time 1 second) to obtain a sample. The obtained sample was subjected to a T-type peel test (Autograph manufactured by Shimadzu Corporation, peel rate 200 mm / min) by a method according to JIS K 6854-3, and the adhesive strength (N / 15 mm) of the sample was determined. It was measured.
The case where the adhesive strength with respect to the PET sheet was 1 N / 15 mm or more was evaluated as good tackiness (◯), and the case where the adhesive strength was less than 1 N / 15 mm was evaluated as poor tackiness (×).

(4) Blocking resistance The adhesive layer side of the labels obtained in Examples and Comparative Examples is overlapped with the label substrate side (adhesion area: 10 mm (peeling direction) × 15 mm (width direction)), load 2 kg / cm ² ( The sample was stored at 40 ° C. for 24 hours under the condition of 196 kPa) and then used for measurement. A T-type peeling test (peeling speed 200 mm / min) was performed by a method according to JIS K 6854-3, and the adhesive strength (N / 15 mm) of the label was measured.
Good anti-blocking property when the adhesive strength is less than 0.1 N / 15 mm (使用), acceptable level when it is 0.1 to 0.2 N / 15 mm (◯), and when it exceeds 0.2 N / 15 mm It was evaluated as poor blocking ability (x).

(5) Adhesive residue deterrence For the labels obtained in Examples and Comparative Examples, a sample similar to (3) was prepared and stored for 1 week at room temperature (23 ° C.), and then the tackiness was measured in the same manner. It peeled and the presence or absence of the adhesive residue on the surface of the adherend (plastic sheet) was visually observed.
When the label peeling and adhesive residue is less than 5% of the adhesive area (10 mm × 15 mm), the adhesive residue deterring property is good (◯), and when it is 5% or more, the adhesive residue deterring property is poor (×). It was evaluated.

(6) Delay characteristics (open time)
The labels obtained in Examples and Comparative Examples are heated at 90 ° C. for 10 seconds using a heating plate, and then separated from the heat source. After leaving at room temperature (23 ° C.) for 30 seconds, on the same PET sheet as in (3) above, normal temperature, 0.1 MPa, 1 second so that the adhesion area becomes 10 mm (peeling direction) × 15 mm (width direction) A sample was sealed under conditions. About the obtained sample, the T-type peeling test was performed similarly to said (3), and adhesive strength (N / 15mm) was measured.
The case where the adhesive strength was 1 N / 15 mm or more was evaluated as good (◯), and the case where the adhesive strength was less than 1 N / 15 mm was evaluated as poor (×).

  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 and 2 show the blending amounts (contents) and evaluation results of the components of Examples and Comparative Examples. In the table, each component of the main component (ethylene copolymer, tackifier, solid plasticizer) and the amount of auxiliary agent are expressed in parts by weight of the solid content of each component.

Example 1
(Label substrate)
A biaxially stretched polypropylene film (trade name “A1”, manufactured by Gunze Co., Ltd.) (thickness 50 μm) was used as a label base material. The heat shrinkage rate in the machine direction (MD direction) and the transverse direction (TD direction) of this film were both less than 1% under the condition of being immersed in a glycerin bath at 100 ° C. for 5 seconds.
(Printing ink)
As the ink, urethane-based ink (“NT Hi-Milac” manufactured by Dainichi Seika Kogyo Co., Ltd.) was used.
(Heat sensitive adhesive)
According to the blending amount in Table 1, ethylene-vinyl acetate copolymer (EVA: ethylene content 72 wt%, melting point 62 ° C., MFR 400 g / 10 min) 25 parts by weight, tackifier (terpene resin, manufactured by Yasuhara Chemical Co., Ltd.) , Trade name “YS Polystar T115”) and 67 parts by weight of a solid plasticizer (dicyclohexyl phthalate) were dispersed in 67 parts by weight of water to obtain a main agent.
Subsequently, an aliphatic urethane resin (manufactured by Nippon Kako Paint Co., Ltd., trade name “FW413”, weight average molecular weight: about 100,000, MFT: 0 ° C., glass transition temperature: 30 ° C. as an auxiliary agent to the obtained main agent. , Solid content of 33%) is mixed with 100 parts by weight of the solid content of the main agent so that the solid content of the auxiliary agent is 15 parts by weight. 70 ° C.).
(Thermal label)
On one surface of the label substrate, the printing ink was printed by gravure printing (design: yellow, white solid, 2 colors (twice coating)) to form a printed layer (thickness 3 μm). Subsequently, the above heat-sensitive adhesive was applied by gravure printing to form an adhesive layer (thickness 4 μm) to obtain a heat-sensitive label (total thickness 57 μm).
(Container with label)
The obtained label is heated from the label base material side while adsorbed to the heating drum (temperature 90 ° C.) to activate the adhesive layer, and then the surface of the adhesive layer side is made of a polyethylene terephthalate bottle (PET bottle). ) To obtain a labeled container.
As shown in Table 1, the obtained thermosensitive label had excellent tackiness, blocking resistance, adhesive residue deterrence and delay properties. Moreover, the mounting property of the thermosensitive label on the container was good, and the appearance of the obtained container was also excellent.
In addition to the above PET bottle, the thermosensitive label of Example 1 was attached to a polypropylene bottle (PP bottle) to produce a labeled container, and an excellent container similar to a PET bottle was obtained. It was.

Example 2
As shown in Table 1, a thermosensitive label and a labeled container were obtained in the same manner as in Example 1 except that the blending amount of the auxiliary agent in the thermosensitive adhesive was changed.
As a result, as shown in Table 1, the obtained thermosensitive label had good tackiness, blocking resistance, adhesive residue deterrence, and delay properties. Moreover, the mounting property of the thermosensitive label on the container was good, and the appearance of the obtained container was also excellent.

Examples 3-5
As shown in Table 1, a heat-sensitive label and a labeled container were obtained in the same manner as in Example 1 except that the adjuvant used for the heat-sensitive adhesive was changed. As an adjuvant, in Example 3, aliphatic urethane resin (manufactured by Nippon Kako Paint Co., Ltd., trade name “FW413-1”, weight average molecular weight: about 50000, MFT: 0 ° C., glass transition temperature: 10 ° C. In Example 4, an aliphatic urethane resin (manufactured by Nippon Kako Paint Co., Ltd., trade name “FW413-2”, weight average molecular weight: about 150,000, MFT: 0 ° C., glass transition temperature) : 50 ° C., solid content 31%), in Example 5, aliphatic urethane resin (manufactured by Nippon Kako Paint Co., Ltd., trade name “FW416-1”, weight average molecular weight: about 200000, MFT: 5 ° C., Glass transition temperature: 40 ° C., solid content 30%) was used.
As a result, as shown in Table 1, the obtained thermosensitive label had good tackiness, blocking resistance, adhesive residue deterrence, and delay properties. Moreover, the mounting property of the thermosensitive label on the container was good, and the appearance of the obtained container was also excellent.

Comparative Examples 1-3
As shown in Table 2, a heat-sensitive label and a labeled container were obtained in the same manner as in Example 1 except that the auxiliary agent used for the heat-sensitive adhesive was changed. As an auxiliary agent, in Comparative Example 1, aliphatic urethane resin (manufactured by Nippon Kako Paint Co., Ltd., trade name “FW415-5”, weight average molecular weight: about 500,000, MFT: 70 ° C., glass transition temperature: 78 ° C. In Comparative Example 2, an aromatic urethane resin (manufactured by Dainippon Ink Co., Ltd., trade name “Hydran AP-30F”, weight average molecular weight: about 10,000, MFT: 60 ° C., glass transition) In Comparative Example 3, an aliphatic urethane resin (manufactured by Nippon Kako Paint Co., Ltd., trade name “FW415-3”, weight average molecular weight: about 500,000, MFT: 55 ° C. Glass transition temperature: 101 ° C., solid content 35%).
As a result, as shown in Table 2, although the obtained thermosensitive label had good tackiness and blocking resistance delay property, it was inferior in adhesive residue deterrence. Moreover, although the mounting property of the heat-sensitive label on the container and the appearance of the container were good, an adhesive residue was generated on the bottle side when the label was peeled off.

Comparative Examples 4 and 5
As shown in Table 2, a thermosensitive label and a labeled container were obtained in the same manner as in Example 1 except that the blending amount of the adjuvant was changed.
As a result, as shown in Table 2, when the content of the auxiliary agent is small (Comparative Example 4) as compared with the specified range of the present invention, the adhesive residue deterring property is inferior, and the thermal label of Comparative Example 4 was used. The container had adhesive residue on the bottle side when the label was peeled off. Further, when the content of the auxiliary agent is large (Comparative Example 5), tackiness and blocking resistance are lowered, and when the heat-sensitive label of Comparative Example 5 is used, mounting failure and blocking occur due to insufficient adhesion. Productivity declined.

Comparative Examples 6 and 7
As shown in Table 2, a thermal label and a labeled container were used in the same manner as in Example 1 except that no auxiliary agent was used in Comparative Example 6 and no solid plasticizer and auxiliary agent were used in Comparative Example 7. Got.
As a result, as shown in Table 2, the heat-sensitive label obtained in Comparative Example 6 was inferior in adhesive residue deterrence, and the container using the heat-sensitive label of Comparative Example 6 had adhesive residue on the bottle side at the time of peeling. . In addition, the heat-sensitive label obtained in Comparative Example 7 was inferior in the delay property, and the tack property was abruptly lowered immediately after the heat activation, so that the workability was poor.

It is a schematic sectional drawing which shows an example of the thermosensitive label of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal label 2 Label base material 3 Print layer 4 Adhesive layer

Claims (4)

  A label in which an adhesive layer and a printing layer are laminated on a label substrate, wherein the adhesive layer is an ethylene copolymer having an ethylene content of 66 to 90% by weight, a tackifier, and a solid plasticizer A heat-sensitive label comprising a delayed type heat-sensitive adhesive containing 10 to 50 parts by weight of an auxiliary agent which is a urethane resin having a weight average molecular weight of 20000 to 300,000 with respect to 100 parts by weight of the main agent.   The heat-sensitive label according to claim 1, wherein a minimum film-forming temperature (MFT) of the urethane-based resin is less than 40 ° C.   The heat-sensitive label according to claim 1 or 2, wherein the print layer is made of urethane-based ink.   A labeled container to which the heat-sensitive label according to claim 1 is attached.

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