JP6135851B2 - label - Google Patents

Description

  The present invention relates to a label. More specifically, the present invention relates to a label having excellent followability and water resistance, excellent economic efficiency, and high environmental suitability.

  Conventionally, for example, a tube container has been used as a container filled with fluid substances such as toothpaste, facial cleansing products, cosmetics, and gel-like pharmaceuticals.

  Designs such as letters and pictures are displayed on the surface of the tube container. As a display method of this design, a method of directly printing on the surface of the tube container is mainly used. However, the above direct printing method has a problem in that the printed layer picks up irregularities on the surface of the tube container, and the decorativeness such as gradation expression is poor. In general, the tube container is formed after direct printing, but there is a part that cannot be printed due to the formation of the tube container, the area of the display part is limited, and the printable area is small. there were. Furthermore, tube containers with a design such as a product name that has been directly printed cannot be used for the purpose of filling a product that is different from the product name when mass-produced. there were.

  As a method for solving the above problem, there is known a method in which a label on which a character or a design is designed is attached to or attached to a tube container (for example, see Patent Documents 1 and 2). As an adhesive used for such a label, an acrylic emulsion type adhesive is known.

JP 2010-105692 A JP 2010-195402 A

  However, the label using the acrylic emulsion-type pressure-sensitive adhesive as described above has insufficient adhesion to fine irregularities on the surface of the adherend such as the tube container, and the tube container is used repeatedly. In some cases, the end of the label may not be able to follow the deformation of the container when squeezed and the end of the label floats from the tube container. The acrylic emulsion-type pressure-sensitive adhesive has poor water resistance, and when the tube container is used in an environment where water is present, the label may float or peel off from the tube container.

  In addition, labels using conventional solvent-type acrylic pressure-sensitive adhesives are excellent in water resistance. However, since a very large drying facility is required to volatilize the solvent at the time of manufacturing the label, the cost becomes high and the economy is high. There was a problem that the nature was bad. In addition, it is not suitable for small and medium-sized production, and the storage period becomes longer due to the production of large lots. This causes a problem that stickiness variation occurs and label floating tends to occur. Furthermore, since a large amount of solvent is volatilized during the production of the label, there is a problem that environmental suitability is low.

  That is, an object of the present invention is to provide a label having excellent followability to deformation of an adherend (particularly, a tube container), excellent water resistance, excellent economic efficiency, and high environmental suitability. Another object of the present invention is to provide a label having excellent environmental resistance.

  As a result of intensive studies to achieve the above object, the present inventors have found that a label has a pressure sensitive adhesive layer formed from a label base material, a printing layer, and an ultraviolet curable acrylic hot melt pressure sensitive adhesive. Since the adhesive agent layer has a gel fraction measured under specific conditions within a specific range, adhesion to fine irregularities on the surface of the adherend (particularly the tube container) is improved. It has been found that a label having excellent followability to deformation of an adherend, excellent water resistance, excellent economic efficiency and high environmental suitability can be obtained, and the present invention has been completed.

That is, the present invention has a pressure-sensitive adhesive layer formed from a label base material, a printing layer, and an ultraviolet curable acrylic hot melt pressure-sensitive adhesive, and the pressure-sensitive adhesive layer has a gel fraction (A ) Is 0 to 30% by weight, and the gel fraction (B) defined below is 70 to 100% by weight.
Gel fraction (A): The weight of the pressure-sensitive adhesive layer wrapped with a 100-mesh wire net is measured, and the weight is defined as the weight before immersion (a1). The pressure-sensitive adhesive layer wrapped with a 100-mesh wire mesh was immersed in tetrahydrofuran for 24 hours, then subjected to ultrasonic irradiation for 1 hour, taken out from tetrahydrofuran, dried and removed, and the weight was measured. The weight after immersion is defined as weight (b1). And a gel fraction (A) is calculated | required from following formula (1).
Gel fraction (A) (% by weight) = (weight after immersion (b1) −weight of mesh of 100 mesh) / (weight before immersion (a1) −weight of wire of 100 mesh) × 100 (1)
Gel fraction (B): The weight of the pressure-sensitive adhesive layer wrapped with a 200 mesh wire net is measured, and the weight is defined as the weight before immersion (a2). The pressure-sensitive adhesive layer wrapped with 200 mesh wire mesh was immersed in tetrahydrofuran for 24 hours, then subjected to ultrasonic irradiation for 1 hour, taken out from tetrahydrofuran, dried and removed, and the weight was measured. The weight is defined as the weight after immersion (b2). And a gel fraction (B) is calculated | required from following formula (2).
Gel fraction (B) (% by weight) = (weight after immersion (b2) −weight of wire mesh of 200 mesh) / (weight before immersion (a2) −weight of wire mesh of 200 mesh) × 100 (2)

  Moreover, this invention provides the labeled container which has the said label.

  The label of this invention has the specific adhesive layer formed from the label base material, the printing layer, and the ultraviolet curable acrylic hot-melt adhesive. Thereby, the label of this invention is excellent in the followable | trackability with respect to a deformation | transformation of a to-be-adhered body (especially tube container), and excellent in water resistance.

It is the schematic (sectional drawing) which shows an example of the label of this invention. It is the schematic which shows an example of the container with a label (tube container with a label) of this invention. It is the schematic which shows an example of the unsealed thing (state which the sealing part is not sealed) of the container main body of the tube container for demonstrating the manufacturing method of the labeled container (tube container with a label) of this invention.

  The label of this invention has at least the adhesive layer formed from the label base material, the printing layer, and the ultraviolet curable acrylic hot melt adhesive. In the present specification, the pressure-sensitive adhesive layer formed from the ultraviolet curable acrylic hot-melt pressure-sensitive adhesive may be referred to as “the pressure-sensitive adhesive layer of the present invention”. The label of this invention may contain layers other than the said label base material, the said printing layer, and the adhesive layer of this invention within the range which does not impair the effect of this invention.

[Label substrate]
The said label base material is not specifically limited, A well-known and usual label base material can be used. Although it does not specifically limit as said label base material, For example, a plastic film, a nonwoven fabric, paper, a synthetic paper, a metal vapor deposition sheet, a foamed resin sheet etc. are mentioned. Of these, plastic film and synthetic paper are preferable.

  The type of resin forming the plastic film and the synthetic paper can be appropriately selected according to the required physical properties, application, cost, etc., and is not particularly limited. For example, polyethylene, polypropylene, cyclic olefin, etc. Examples thereof include polyolefin resins, polyester resins such as polyethylene terephthalate, polyvinyl chloride resins, polyamide resins, and polystyrene resins. Among these, polyolefin resins are preferable from the viewpoint of followability to the tube container when squeezed and label rigidity at the time of labeling. Only 1 type may be used for the said resin and 2 or more types may be used for it.

  Examples of the polyolefin resin include polyethylene resins such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and metallocene catalyst LLDPE (mLLDPE), polypropylene such as polypropylene and propylene-α-olefin copolymer. Resin, ethylene-vinyl acetate copolymer, cyclic olefin resin and the like. Among these, a polypropylene resin is preferable.

  The plastic film may have a single layer structure or a laminated structure. That is, 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 the same kind of resin may be laminated, or film layers made of different resins may be laminated.

  The plastic film may be a non-oriented film or an oriented film. Among these, a film oriented in a uniaxial, biaxial or polyaxial manner is preferable. When the plastic film is a laminated film, it is preferable that at least one film layer in the laminated film is oriented. The plastic film is preferably a uniaxial or biaxially oriented film, and more preferably a film oriented in the biaxial direction of the film (a biaxially stretched film).

  The surface of the plastic film may be subjected to conventional surface treatment such as corona discharge treatment or primer treatment, if necessary.

  The plastic film can be produced by a conventional method such as melt film formation or solution film formation. It is also possible to use a commercially available plastic film. When producing a laminated plastic film, a conventional method such as a co-extrusion method or a dry laminating method can be used as a laminating method. Examples of methods for orienting the plastic film include 2 in the longitudinal direction (film production line direction; also referred to as the longitudinal direction or MD direction) and the width direction (direction orthogonal to the longitudinal direction; also referred to as lateral direction or TD direction). Axial stretching, uniaxial stretching in the longitudinal direction or width direction, and the like can be used. As the stretching method, for example, a roll method, a tenter method, a tube method, or the like can be used.

  The plastic film may be a non-heat-shrinkable film (for example, a biaxially stretched film) or a heat-shrinkable film. The above-mentioned plastic film is preferably a non-heat-shrinkable film because the above-mentioned label base material is difficult to shrink due to heat when the pressure-sensitive adhesive layer of the present invention is melt-coated.

  That is, the label substrate is not particularly limited, but among them, a plastic film is preferable, more preferably a polyolefin film, still more preferably a polypropylene film, and particularly preferably a biaxially stretched polypropylene film. When the label base material is a biaxially stretched polypropylene film, the label itself has high rigidity, so that the thickness of the container to which the label is attached can be reduced, which leads to cost reduction of the container. Moreover, since it is easy to follow the deformation | transformation of the tube container at the time of tube use when attaching to a tube container, it is preferable.

  The label substrate may be either transparent or opaque. In the case of a label base material excellent in transparency, the haze value [based on JIS K 7136, converted to a thickness of 40 μm, unit:%] of the label base material is preferably less than 7.0%, more preferably 5. Less than 0%. When the haze value is 7.0% or more, in the case of a back-printed (type that shows printing through a label base material) label, the printing may become cloudy and the decorativeness may be lowered when the product is made. However, even if the haze value is 7.0% or more, the haze value can be sufficiently used in applications other than the above-described back printing application. The label base material excellent in transparency is preferably colorless, but may be colored as long as transparency is not impaired.

  The thickness of the label substrate is not particularly limited, but is preferably 20 to 75 μm, more preferably from the viewpoint of improving the followability to deformation of the adherend and improving the waist of the tube container when the adherend is a tube container. Is 30-60 μm. When the thickness is 20 μm or more, the rigidity of the tube container equipped with the label can be made constant or more, which is preferable. When the thickness is 75 μm or less, it is possible to follow the deformation of the tube container when the tube container is used, which is preferable.

[Print layer]
The print layer is not particularly limited, and examples thereof include print layers used in known labels such as a solvent-drying print layer and an ultraviolet curable print layer. Examples of the print layer include a layer displaying a product name, an illustration, handling precautions, and the like.

  Although the said printing layer is not specifically limited, It is preferable that binder resin is included as an essential component. Furthermore, it is preferable that a pigment, a wax, and an active agent are included as necessary. Each of the binder resin, the pigment, the wax, and the active agent may be used alone or in combination of two or more.

  It does not specifically limit as said binder resin, For example, resin used as binder resin in a well-known printing layer and printing ink can be used. Examples of the binder resin include acrylic resins, urethane resins, polyester resins, polyamide resins, cellulose resins (including nitrocellulose resins), urethane acrylic resins, and vinyl chloride-vinyl acetate copolymer resins. Etc. It does not specifically limit as said pigment, For example, the pigment used in a well-known printing layer and printing ink can be used. As the pigment, for example, a white pigment such as titanium oxide (titanium dioxide), an indigo pigment such as copper phthalocyanine blue, carbon black, aluminum flakes, mica (mica), and other colored pigments can be selected and used according to the application. In addition to the above pigments, extender pigments such as alumina, calcium carbonate, barium sulfate, silica, and acrylic beads can also be used for the purpose of adjusting gloss.

  Although the thickness of the said printing layer is not specifically limited, 0.1-5 micrometers is preferable. If the thickness is less than 0.1 μm, it may be difficult to provide a uniform printing layer, causing partial “smearing” and deteriorating decorating properties, or making printing as designed difficult. There is a case. If the thickness exceeds 5 μm, a large amount of printing ink is consumed, which may increase the cost, make it difficult to apply uniformly, or make the printing layer brittle and easy to peel off. .

  Although the said printing layer is not specifically limited, You may be provided only in the single side | surface side of the said label base material, and may be provided in the both surfaces side of the said label base material. Moreover, the said printing layer may be provided in the whole surface of the said label base material (surface on the side in which a printing layer is provided), and may be provided in part.

[Adhesive layer of the present invention]
The label of the present invention has a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer of the present invention) formed from an ultraviolet curable acrylic hot melt pressure-sensitive adhesive. By having the pressure-sensitive adhesive layer of the present invention, the label of the present invention has improved adhesion to fine irregularities on the surface of an adherend such as a tube container, and is excellent in followability to deformation of the container and water resistance. The pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably provided on at least one side of the label base material. The pressure-sensitive adhesive layer of the present invention is a pressure-sensitive pressure-sensitive adhesive layer.

The gel fraction (A) defined below of the pressure-sensitive adhesive layer of the present invention is 0 to 30% by weight, preferably 0 to 20% by weight, more preferably 0 to 10% by weight. When the gel fraction (A) exceeds 30% by weight, the adhesion of the label to the fine irregularities on the surface of the adherend is lowered, and the followability to the deformation of the container is deteriorated.
Gel fraction (A): The weight of the pressure-sensitive adhesive layer wrapped with a 100-mesh wire net is measured, and the weight is defined as the weight before immersion (a1). The pressure-sensitive adhesive layer wrapped with a 100-mesh wire mesh was immersed in tetrahydrofuran for 24 hours, then subjected to ultrasonic irradiation for 1 hour, taken out from tetrahydrofuran, dried and removed, and the weight was measured. The weight after immersion is defined as weight (b1). And a gel fraction (A) is calculated | required from following formula (1).
Gel fraction (A) (% by weight) = (weight after immersion (b1) −weight of mesh of 100 mesh) / (weight before immersion (a1) −weight of wire of 100 mesh) × 100 (1)

The gel fraction (B) defined below of the pressure-sensitive adhesive layer of the present invention is 70 to 100% by weight, preferably 75 to 100% by weight, and more preferably 80 to 100% by weight. If the said gel fraction (B) is less than 70 weight%, moderate hardness as an adhesive layer is not acquired, and the water resistance of an adhesive layer falls.
Gel fraction (B): The weight of the pressure-sensitive adhesive layer wrapped with a 200 mesh wire net is measured, and the weight is defined as the weight before immersion (a2). The pressure-sensitive adhesive layer wrapped with 200 mesh wire mesh was immersed in tetrahydrofuran for 24 hours, then subjected to ultrasonic irradiation for 1 hour, taken out from tetrahydrofuran, dried and removed, and then the weight was measured. The weight is defined as the weight after immersion (b2). And a gel fraction (B) is calculated | required from following formula (2).
Gel fraction (B) (% by weight) = (weight after immersion (b2) −weight of wire mesh of 200 mesh) / (weight before immersion (a2) −weight of wire mesh of 200 mesh) × 100 (2)

  The gel fraction (A) and the gel fraction (B) are the composition, weight average molecular weight, and content of an acrylic prepolymer that is a base polymer of an ultraviolet curable acrylic hot melt pressure-sensitive adhesive; It can be adjusted by the type and content of the photopolymerization initiator contained in the hot melt adhesive; the amount of ultraviolet light (integrated light amount) irradiated to form the adhesive layer of the present invention.

  When the biaxially stretched polyolefin-based film having high rigidity is used as the label substrate by setting the gel fraction (A) and the gel fraction (B) within the specific ranges, respectively. Even so, the followability to deformation of the tube container with the label is excellent.

  Although the thickness of the adhesive layer of this invention is not specifically limited, 10-40 micrometers is preferable, More preferably, it is 15-30 micrometers. When the thickness is 10 μm or more, the adhesive strength of the label to the adherend and the followability to deformation of the adherend are excellent, which is preferable. It is preferable that the thickness is 40 μm or less because of the stamping suitability and release suitability of the label.

  The ultraviolet curable acrylic hot-melt pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the present invention is not particularly limited as long as it contains an acrylic prepolymer as a base polymer and can be cured (crosslinked) by ultraviolet light. . The ultraviolet curable acrylic hot melt pressure-sensitive adhesive is not particularly limited, but preferably contains at least an acrylic prepolymer, a photopolymerization initiator, and a tackifier. The ultraviolet curable acrylic hot melt pressure-sensitive adhesive may contain components (other components) other than the acrylic prepolymer, the photopolymerization initiator, and the tackifier.

<Acrylic prepolymer>
The acrylic prepolymer is not particularly limited as long as it is an acrylic prepolymer that can be cross-linked by ultraviolet rays, but a prepolymer composed of an acrylic monomer as an essential monomer component, that is, an acrylic monomer. Examples thereof include a prepolymer containing at least a structural unit (structural unit) derived from the body. Examples of the structural unit derived from the acrylic monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and butyl (meth) acrylate. , Isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( (Meth) acrylic acid alkyl ester having a linear or branched alkyl group such as isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate [preferably having 1 to 12 carbon atoms] having a certain linear or branched alkyl group (meth) acrylic acid alkyl ester ((meth) acrylic acid C _1-12 Alkyl ester), etc.]; (meth) acrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid and other carboxyl group-containing polymerizable unsaturated compounds or anhydrides thereof; 2-hydroxymethyl (meth) acrylate, 2-hydroxy Hydroxyl group-containing (meth) acrylic acid esters such as propyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, diethylene glycol mono (meth) acrylate and dipropylene glycol mono (meth) acrylate [Preferably (meth) acrylic acid hydroxy C _1-8 alkyl ester and the like] and the like. As the structural unit derived from the acrylic monomer, only one type may be used, or two or more types may be used. “(Meth) acryl” means “acryl” and / or “methacryl” (one or both of “acryl” and “methacryl”).

  In addition to the above, as required, (meth) acrylic acid cycloalkyl esters such as cyclohexyl (meth) acrylate; hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di ( Multifunctional (meth) acrylic acid esters such as (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate; N-methylol (meth) (Meth) acrylic acid amide derivatives such as acrylamide, N-butoxymethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide; (Meth) acrylic acid dialkylaminoalkyl esters such as di (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, dipropylaminopropyl (meth) acrylate Alkoxy group-containing (meth) acrylic acid ester such as methoxymethyl (meth) acrylate and 2-methoxyethyl (meth) acrylate; benzyl (meth) acrylate, 3,5-di-t- (meth) acrylate Butyl-4-hydroxybenzyl, N-benzyl (meth) acrylamide, N, N-dibenzyl (meth) acrylamide, 4- (diphenylamino) benzyl (meth) acrylate, α-methylbenzyl (meth) acrylate, (meta ) 4-methyl methacrylate Benzyl group-containing (meth) acrylic acid esters such as 4-methoxybenzyl (meth) acrylate; styrene compounds such as styrene, vinyltoluene and α-methylstyrene; vinyl esters such as vinyl acetate and vinyl propionate; Vinyl halides such as vinyl chloride; Vinyl ethers such as methyl vinyl ether; Cyano group-containing vinyl compounds such as (meth) acrylonitrile; Polymerizable unsaturated compounds such as olefins and dienes such as ethylene and propylene as monomer components It can also be used. Only 1 type may be used for the said polymerizable unsaturated compound, and 2 or more types may be used for it.

  The acrylic prepolymer is not particularly limited, and the acrylic monomer and the polymerizable unsaturated compound may be polymerized in the presence of an iniferter. Here, the iniferter is a radical initiator having a polymerization termination function by radical chain transfer, and is capable of chain transfer with a radical having a polymerization initiation function by receiving active energy rays or heat. A relatively stable radical that can be dissociated again after chain transfer is generated.

  The iniferter is not particularly limited. For example, N, N, N ′, N′-tetraethylthiuram disulfide, N, N, N ′, N′-tetramethylthiuram disulfide, N, N′-diethyl-N , N′-bis (2-hydroxyethyl) thiuram disulfide, N, N′-bis [N- (2-phthalimidoethyl)] piperazine thiuram disulfide, N, N-dimethylthiuram disulfide, N, N′-diethylthiuram disulfide Benzyl diethyldithiocarbamate, p-xylene bis (N, N-diethyldithiocarbamate), p-xylene bis (N, N-dimethyldithiocarbamate), n-butyl-N, N-dimethyldithiocarbamate, benzyldithiocarbamate, And benzyl-N, N-dimethyldithiocar Formate and the like. Of these, N, N, N ′, N′-tetraethylthiuram disulfide and benzyl diethyldithiocarbamate are preferred. The amount of the iniferter used is preferably 0.001 to 0.5% by weight, more preferably 0.005%, based on the total weight (100% by weight) of the monomer components constituting the acrylic prepolymer. ~ 0.10% by weight.

  In the polymerization of the acrylic prepolymer, a polymerization initiator such as a photopolymerization initiator or a thermal polymerization initiator can be used depending on the type of polymerization reaction. Among these, it is preferable to use a thermal polymerization initiator. The said polymerization initiator may be used only by 1 type, and may use 2 or more types. The polymerization of the acrylic prepolymer is more preferably performed in the presence of an iniferter and a thermal polymerization initiator from the viewpoint of reducing unreacted monomers during the polymerization.

  The thermal polymerization initiator is not particularly limited. For example, di-3-methoxybutyl peroxydicarbonate, di-2-ethylhexylperoxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, Diisopropyl peroxydicarbonate, t-butyl peroxyisopropyl carbonate, dimyristyl peroxycarbonate, 1,1,3,3-tetramethylbutyl neodecanoate, α-cumyl peroxyneodecanoate, t-butyl Peroxyneodecanoate, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 1,1-bis (t- Butylperoxy) cyclododecane, t-hexylperoxyisop Pyrmonocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxy-2-ethylhexane, 2,5 dimethyl-2,5-di (Benzoylperoxy) hexane, t-butylperoxyacetate, 2,2-bis (t-butylperoxy) butene, t-butylperoxybenzoate, n-butyl-4,4-bis (t-beroxy) valerate , Di-t-butylberoxyisophthalate, dicumyl peroxide, α, α′-bis (t-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butyl) Peroxy) hexane, 1,3-bis (t-butylperoxydiisopropyl) benzene, t-butylcumyl peroxide, di t-butyl peroxide, p- menthane hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) such as hexyne-3 and the like. Only 1 type may be used for the said thermal-polymerization initiator, and 2 or more types may be used for it.

  The photopolymerization initiator used when polymerizing the acrylic prepolymer is not particularly limited, but the photopolymerization initiator exemplified as the photopolymerization initiator contained in the ultraviolet curable acrylic hot melt pressure-sensitive adhesive is used. Can be used. Only 1 type may be used for the said photoinitiator, and 2 or more types may be used for it.

<Photopolymerization initiator>
Although it does not specifically limit as a photoinitiator (photoinitiator different from the photoinitiator used when superposing | polymerizing the said acrylic type prepolymer) contained in the said ultraviolet curing acrylic hot-melt adhesive agent, Any known and commonly used photopolymerization initiator can be used. The photopolymerization initiator is not particularly limited, but is a benzoin ether photopolymerization initiator, an acetophenone photopolymerization initiator, an α-ketol photopolymerization initiator, an aromatic sulfonyl chloride photopolymerization initiator, a photoactive oxime. And photopolymerization initiators, benzoin photopolymerization initiators, benzyl photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, and thioxanthone photopolymerization initiators. Only 1 type may be used for the said photoinitiator, and 2 or more types may be used for it.

  The benzophenone photopolymerization initiator is not particularly limited, and examples thereof include benzophenone, 4-chlorobenzophenone, 4,4′-dimethylbenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, o-benzoylbenzoate. Acid methyl, 3,3′-dimethyl-4-methoxybenzophenone, 4-phenylbenzophenone, 4-benzoyl-4′-methyl-diphenyl sulfide, 4-morpholinobenzophenone, 4,4′-diphenoxybenzophenone, 4-hydroxy And benzophenone, 2-carboxybenzophenone, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methyl-propan-1-one, and the like. . Among these, benzophenone, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) can be obtained because it can be cured with a small amount of UV irradiation and has excellent basic adhesive properties. ) -Benzyl] -phenyl} -2-methyl-propan-1-one is preferred. As for the said benzophenone series photoinitiator, only 1 type may be used and 2 or more types may be used.

<Tackifier>
The tackifier is not particularly limited, and examples thereof include tackifier resins such as rosin resins, terpene resins, petroleum resins, coumarone-indene resins, and styrene resins. Among these, it is preferable to include petroleum resins and terpene resins.

  The ultraviolet curable acrylic hot melt pressure-sensitive adhesive is not particularly limited, but may contain components other than the acrylic prepolymer, the photopolymerization initiator, and the tackifier within a range not impairing the effects of the present invention. Good. Components other than the acrylic prepolymer, the photopolymerization initiator, and the tackifier are not particularly limited. For example, a filler such as a plasticizer, a crosslinking agent, and fine powder silica, a colorant, an ultraviolet absorber, An antioxidant etc. are mentioned.

  Although it does not specifically limit as said crosslinking agent, For example, polyfunctional (meth) acrylate; Polyisocyanate type crosslinking agent; Epoxy type crosslinking agent; Melamine type crosslinking agent; Aziridine type crosslinking agent; Magnesium, calcium, barium, zinc etc. Divalent metals; Halides of trivalent metals such as aluminum and iron; Sulfates and nitrates of these metals; Metal chelate-based crosslinking agents and the like. Only 1 type may be used for the said crosslinking agent, and 2 or more types may be used for it.

  Although content of the said acrylic type prepolymer is not specifically limited, 70 to 95 weight% is preferable with respect to the total weight (100 weight%) of the said ultraviolet curing acrylic hot-melt adhesive, More preferably, it is 75- 90% by weight. When the content is less than 70% by weight, the cohesive force of the pressure-sensitive adhesive layer may be lowered. If the content exceeds 95% by weight, the adhesive strength of the label to the adherend may be lowered.

  The weight average molecular weight of the acrylic prepolymer is not particularly limited, but is preferably 10,000 to 500,000, more preferably 50,000 to 400,000. When the weight average molecular weight is less than 10,000, the cohesive force of the pressure-sensitive adhesive layer is lowered, and the adhesive strength of the label to the adherend may be lowered. When the polymerization average molecular weight exceeds 500,000, the adhesive strength of the label to the adherend and the followability to deformation of the adherend may be lowered.

  The content of the photopolymerization initiator (the photopolymerization initiator contained in the ultraviolet curable acrylic hot melt pressure-sensitive adhesive) is not particularly limited, but is the total weight (100 weight) of the ultraviolet curable acrylic hot melt pressure sensitive adhesive. %) Is preferably 0.05 to 5% by weight, more preferably 0.06 to 4% by weight, and still more preferably 0.07 to 1% by weight. When the content is less than 0.05% by weight, the pressure-sensitive adhesive may not be sufficiently cured by irradiation with ultraviolet rays. If the content exceeds 5% by weight, the cohesive force of the acrylic prepolymer becomes too high, and a pressure-sensitive adhesive layer having sufficient tackiness after curing may not be obtained.

  Although content of the said tackifier is not specifically limited, 1-20 weight% is preferable with respect to the total weight (100 weight%) of the said ultraviolet curing acrylic hot-melt adhesive, More preferably, it is 2-15. % By weight. When the content is less than 1% by weight, the adhesive strength of the label to the adherend may be lowered. When the content exceeds 20% by weight, the cohesive force of the pressure-sensitive adhesive layer is lowered, and the adhesive strength may be lowered.

  In addition, in this invention, content (weight%) of each component of the said ultraviolet curing acrylic hot-melt adhesive is content (weight%) of each component in the adhesive layer of this invention of the label of this invention. Is equal to

  A commercial item can also be used for the said ultraviolet curing acrylic hot-melt adhesive. For example, “RC26100” manufactured by NOVAMELT GmbH may be used.

[Label of the present invention]
The label of the present invention has at least the label substrate, the printed layer, and the pressure-sensitive adhesive layer of the present invention. Further, the label of the present invention includes, in addition to the label base material, the printed layer, and the pressure-sensitive adhesive layer of the present invention, a pressure-sensitive adhesive layer (adhesive layer) other than the pressure-sensitive adhesive layer of the present invention, an antistatic layer, an anchor. A coating layer, a primer coating layer, a coating layer (surface protective layer) and the like may be provided as necessary.

  The layer structure of the label of the present invention is not particularly limited, but label substrate / printing layer / pressure-sensitive adhesive layer of the present invention; printing layer / label base material / pressure-sensitive adhesive layer of the present invention; printing layer / label base material / printing Layer / pressure-sensitive adhesive layer of the present invention; coating layer (surface protective layer) / printing layer / label base material / pressure-sensitive adhesive layer of the present invention; coating layer (surface protective layer) / printing layer / label base material / printing layer / book Examples include the pressure-sensitive adhesive layer of the invention. The label of the present invention may be a so-called front printing (type that shows printing from the printing layer side) label or back printing (type that shows printing through a label substrate), but a back printing label is preferred. In the case of the above-mentioned label for surface printing, when the printing layer is provided on one side of the label base material, the pressure-sensitive adhesive layer of the present invention is provided on the surface of the label base material on which the printing layer is not provided. Can be manufactured. Moreover, when the printing layer is provided on the one side of the label base material, the label of the back printing is provided with the pressure-sensitive adhesive layer of the present invention on the side of the label base material on which the printing layer is provided. It can manufacture by providing on the surface.

  FIG. 1 is a schematic view (cross-sectional view) showing an example of a label of the present invention (back printing label). The label 1 of the present invention shown in FIG. 1 includes a label base material 11, a printing layer 12 provided on one side of the label base material 11, and a surface of the label base material 11 on the side having the printing layer 12. It has the adhesive layer 13 of this invention provided.

  Although the thickness (total thickness) of the label of this invention is not specifically limited, 30-120 micrometers is preferable, More preferably, it is 45-95 micrometers. If the thickness of the label of the present invention is less than 30 μm, the effect of improving the rigidity of the container equipped with the label may not be obtained. If the thickness of the label of the present invention exceeds 120 μm, it may be difficult to follow the deformation of the tube container when the tube container is used.

  The label of the present invention can be used as a tack label (pressure-sensitive adhesive label) and attached to a container by attaching the pressure-sensitive adhesive layer of the present invention so as to come into contact with the container to produce a labeled container. By using a container with a label, it is possible to improve the decorating property, expand the display area of the design, and reduce the cost by improving the production efficiency, compared to a conventional container that prints on the surface of the container. Moreover, since the label has a certain degree of rigidity, the container body can be thinned. In addition, the label of this invention may be used for adherends other than a container.

  Although it does not specifically limit as said container, For example, tube containers, such as a container used for toothpaste, a shampoo, a conditioner, etc., a blow container used for mayonnaise etc .; a container (squeeze), such as a pouch container; a cup container The container which has property, a squeeze container) etc. are mentioned as a preferable container. Among these, the container is particularly preferably a tube container. The tube container refers to a squeeze container that can be used by extruding the contents of the container by applying pressure to the container from the outside of the container. The material of the container is not particularly limited, and examples thereof include polyethylene (low density polyethylene (LDPE), high density polyethylene (HDPE), etc.), polypropylene, ethylene-vinyl alcohol copolymer, plastics such as PET, and the like. Can be mentioned. Therefore, the label of the present invention is preferably a squeeze container label, and particularly preferably a tube container label. The labeled container of the present invention is preferably a labeled squeeze container, and particularly preferably a labeled tube container.

  Although the label of the present invention is not particularly limited, by forming the printed layer on at least one side of the label substrate, and further forming the pressure-sensitive adhesive layer of the present invention on at least one side of the label substrate, Can be manufactured.

  The printed layer can be formed by applying the ink composition onto the surface of the label base material and then solidifying it. As a method for applying the printing ink, a gravure printing method, a flexographic printing method, and a letterpress printing method are preferable from the viewpoints of cost, productivity, printing decoration, and the like, and a gravure printing method is particularly preferable. Moreover, when the applied printing ink layer (coating layer) is dried and solidified by heating or the like, a general heating device capable of heating on the printing device can be preferably used. From the viewpoint of safety, a hot air heater or the like can be preferably used. The printed layer may be solidified by an active energy ray such as ultraviolet rays.

  The pressure-sensitive adhesive layer of the present invention is not particularly limited, but the ultraviolet curable acrylic hot melt pressure-sensitive adhesive that has been melted by heat is applied to at least one side of the label base material, and after cooling, irradiated with ultraviolet rays. It can be formed by curing.

  Although the melting temperature in the case of the said heat melting is not specifically limited, 80-180 degreeC is preferable, More preferably, it is 100-160 degreeC.

  The method for applying the heat-melted UV-curable acrylic hot melt pressure-sensitive adhesive is not particularly limited, and a known and commonly used method for applying a hot-melt pressure-sensitive adhesive can be used. Specifically, for example, coating devices such as slot die coaters, gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, direct coaters, etc. Examples include the coating method used. Of these, a slot die coater is preferable.

  Moreover, it does not specifically limit as an apparatus (ultraviolet irradiation apparatus) for irradiating the said ultraviolet-ray, A well-known and usual active energy ray irradiation apparatus can be used. For example, a high pressure discharge lamp such as a metal halide lamp and a high pressure mercury lamp, a low pressure discharge lamp such as a chemical lamp, a black light lamp, and a fluorescent lamp for trapping are preferable.

Although the light quantity (integrated light quantity) of the ultraviolet rays irradiated for forming the pressure-sensitive adhesive layer of the present invention is not particularly limited, it is preferably 10 to 200 mJ / cm ² , more preferably 30 to 160 mJ / cm ² .

  The label of the present invention has an adhesive layer formed from an ultraviolet curable acrylic hot melt adhesive having specific physical properties. For this reason, the adhesiveness with respect to a fine unevenness | corrugation improves on the surface of adherends, such as a tube container, and it is excellent in the followability with respect to a deformation | transformation of a container. In addition, the excellent adhesiveness minimizes the gap between the container (particularly the tube container) and the label pressure-sensitive adhesive layer of the labeled container, so that there is no gap between the container and the pressure-sensitive adhesive layer. Water is less likely to enter and has better water resistance.

  The label of the present invention has a gel fraction (gel fraction (A)) of 0 to 30% by weight when measured using a 100-mesh wire mesh of the pressure-sensitive adhesive layer. For this reason, the said adhesive layer has moderate softness | flexibility, and has the outstanding adhesiveness with respect to the unevenness | corrugation of the surface of a to-be-adhered body. The label of the present invention has a gel fraction (gel fraction (B)) of 70 to 100% by weight when measured using a 200-mesh wire mesh of the pressure-sensitive adhesive layer. For this reason, the said adhesive layer is a moderately hard state. Therefore, the label of the present invention is UV-cured because the pressure-sensitive adhesive layer has a gel fraction (A) of 0 to 30% by weight and a gel fraction (B) of 70 to 100% by weight. Among the pressure-sensitive adhesive layers formed from the type acrylic hot-melt pressure-sensitive adhesive, it is possible to achieve both excellent followability to deformation of the adherend and water resistance.

  In the present invention, the gel fraction of the pressure-sensitive adhesive layer is measured under specific conditions using two types of wire mesh (that is, a 100 mesh wire mesh and a 200 mesh wire mesh) having slightly different mesh sizes. By setting the ratio (A) and the gel fraction (B) to a specific range, it is possible to distinguish between a pressure-sensitive adhesive layer and other pressure-sensitive adhesive layers that are compatible with the deformation of the adherend and water resistance. It was. Although this is not certain, it is assumed that the pressure-sensitive adhesive layer of the present invention is microgelled in an organic solvent.

  An example of the labeled container of the present invention and the manufacturing method thereof will be described with reference to FIGS. FIG. 2 is a schematic view showing an example of a tube container (a container with a label of the present invention) equipped with the label of the present invention. The labeled container 3 has the label 1 of the present invention around the side surface of the body portion 21 of the container body 20. Specifically, the labeled container 3 includes the tube container 2 having the container body 20 and the label 1 of the present invention, and the label 1 is attached to the side surface of the trunk portion 21 of the container body 20 by the adhesive layer of the present invention. It is stuck. The tube container 2 has a cylindrical body portion 21, a sealing portion 22 formed by sealing one side of the body portion 21 in a flat shape, and an extraction port 23 provided on the other side of the body portion 21. A main body 20 and a cap 24 attached to the extraction port 23 are included. The label 1 of the present invention is wound so as to cover substantially the entire side surface of the body portion 21 of the container body 20, and the other end portion of the label 1 is superimposed on one end portion of the label 1 adhered to the side surface. In addition, a polymerized portion 25 is formed by sticking with the adhesive layer of the present invention.

  The labeled container (labeled tube container) of the present invention can be produced, for example, as follows. FIG. 3 is a schematic view showing an example of an unsealed material of the container body 20 of the tube container 2 used for manufacturing the labeled container (labeled tube container) of the present invention. A cylindrical body 21, one of the body parts 21 has an opening 220 in which a sealing part 22 is formed by sealing, and an extraction port 23 provided on the other side. The unsealed material is created by molding such as extrusion molding.

  The manufacturing method of the labeled container of this invention has the sticking process which affixes the label 1 on a container. In this process, after the label 1 is peeled off from the release liner or the like by, for example, a tack labeler, one end thereof is stuck to the container, and the other end is stuck to the one end while being wrapped around the container. Pasted. Specifically, with the cylindrical mandrel inserted into the opening 220 of the unsealed object of the container body 20 in FIG. An attached unsealed product is obtained. Thereafter, a cap 24 is attached to the extraction port 23, and the sealing portion 22 is formed by heat-sealing the opening 220, and the labeled container of the present invention is manufactured.

EXAMPLES 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 gel fraction (A) and gel fraction (B) of the pressure-sensitive adhesive layer used in Examples and Comparative Examples, and evaluation results of the obtained labels.

Example 1
(label)
A printing layer (3 μm) was formed by gravure printing on one surface of a biaxially stretched polypropylene film (trade name “Pyrene”, 50 μm, manufactured by Toyobo Co., Ltd.). Next, an ultraviolet curable acrylic hot melt pressure-sensitive adhesive (manufactured by NOVAMELT GmbH, trade name “RC26100”, weight average molecular weight of acrylic prepolymer: about 100,000) on the surface of the easy release layer of the release liner having the easy release layer Was coated at 135 ° C. using a slot die coater. After that, an adhesive layer (20 μm) was formed by irradiating ultraviolet rays at a process speed of 50 m / min so as to obtain an integrated light amount of 120 mJ / cm ² . After that, the printing layer provided on the biaxially stretched polypropylene and the pressure-sensitive adhesive layer provided on the release liner are laminated and laminated, and the label is protected by the release liner by cutting out into a label shape with a die-cut roll. Got.

(Container with label)
The label obtained above was peeled from the release liner and mounted on a tube container (the surface was made of high-density polyethylene) to obtain a labeled container shown in FIG. In addition, the manufacturing method of the tube container was performed as mentioned above.

Example 2
A label and a container with a label were obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive layer (20 μm) was formed by irradiating with ultraviolet rays at a process speed of 50 m / min so that the integrated light amount was 60 mJ / cm ² .

Example 3
A label and a container with a label were obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive layer (20 μm) was formed by irradiating ultraviolet rays at a process speed of 50 m / min so as to obtain an integrated light quantity of 30 mJ / cm ² .

Comparative Example 1
Except for using an ultraviolet curable acrylic hot melt adhesive containing an acrylic prepolymer having a weight average molecular weight of about 50,000 as the ultraviolet curable acrylic hot melt adhesive, the same as in Example 2, A label and a labeled container were obtained.

Comparative Example 2
Except for using an ultraviolet curable acrylic hot melt adhesive containing an acrylic prepolymer having a weight average molecular weight of about 50,000 as the ultraviolet curable acrylic hot melt adhesive, the same as in Example 1, A label and a labeled container were obtained.

Comparative Example 3
A label and a label in the same manner as in Example 1 except that an ultraviolet curable acrylic hot melt adhesive (manufactured by NOVAMELT GmbH, trade name “RC21511”) was used as the ultraviolet curable acrylic hot melt adhesive. An attached container was obtained.

(Evaluation)
The following evaluation was performed about the label obtained by the Example and the comparative example. The evaluation results are shown in Table 1.

(1) Gel fraction of pressure-sensitive adhesive layer (A)
From the labels obtained in Examples and Comparative Examples, 1.0 g of the pressure-sensitive adhesive layer was collected and used as a measurement sample. The weight of the measurement sample wrapped with a 100-mesh wire mesh was measured and used as the weight before immersion. The measurement sample wrapped with a 100 mesh wire mesh was immersed in tetrahydrofuran at 23 ° C. for 24 hours, then subjected to ultrasonic irradiation for 1 hour, taken out from tetrahydrofuran, dried at 80 ° C. for 24 hours, and tetrahydrofuran. Was removed. The weights of the measurement sample after immersion and the 100-mesh wire mesh were measured and used as the weight after immersion. And the gel fraction (A) was calculated | required from the following formula.
Gel fraction (A) (% by weight) = (weight after immersion−100 mesh wire weight) / (weight before immersion−100 mesh wire mesh weight) × 100

(2) Gel fraction of adhesive layer (B)
From the labels obtained in Examples and Comparative Examples, 1.0 g of the pressure-sensitive adhesive layer was collected and used as a measurement sample. The weight of the measurement sample wrapped with a 200 mesh wire net was measured and used as the weight before immersion. The sample for measurement was wrapped in a 200-mesh wire mesh, immersed in tetrahydrofuran at 23 ° C. for 24 hours, then subjected to ultrasonic irradiation for 1 hour, taken out from tetrahydrofuran, dried at 80 ° C. for 24 hours, and tetrahydrofuran. Was removed. The weights of the measurement sample after immersion and the 200-mesh wire mesh were measured and used as the weight after immersion. And the gel fraction (B) was calculated | required from the following formula.
Gel fraction (B) (% by weight) = (weight after immersion−weight of 200 mesh wire mesh) / (weight before immersion−weight of 200 mesh wire mesh) × 100

(3) Environmental resistance (temperature cycle test)
The labeled containers obtained in Examples and Comparative Examples were stored at −5 ° C. for 1 hour, and then stored at 65 ° C. for 1 hour. The above storage was defined as one cycle, and a total of three cycles were repeated, and the subsequent label state was observed. And environmental tolerance was evaluated on the following reference | standard.
Good (O): No occurrence of floating, or floating area is less than 5% of the entire area where the label is applied Defective (X): The area of the floating is 5 relative to the area of the entire attached area of the label %that's all

(4) Follow-up performance (squeeze evaluation)
Press the sample of the labeled container obtained in the example and the comparative example with the finger on the center of the body of the container (the center of the surface formed by the sealing part) until the inner surfaces of the containers contact each other. This was performed 200 times at the same location, and the state of the subsequent label was observed. The following performance was evaluated according to the following criteria.
Good (O): No occurrence of floating, or floating area is less than 5% of the entire area where the label is applied Defective (X): The area of the floating is 5 relative to the area of the entire attached area of the label %that's all

(5) Water resistance (squeeze evaluation)
The sample with the cap of the labeled container obtained in Examples and Comparative Examples removed was immersed in water at 23 ° C. for 24 hours. Thereafter, the container with the label is taken out of the water, and the center of the body of the container (the center of the surface formed by the sealing part) is pushed with a finger until the inner surfaces of the containers with the label come into contact with each other. After that, the state of the label after that was observed. The following performance was evaluated according to the following criteria.
Good (O): No occurrence of floating, or floating area is less than 5% of the entire area where the label is applied Defective (X): The area of the floating is 5 relative to the area of the entire attached area of the label %that's all

(6) Water resistance (adhesion strength evaluation)
The adhesive strength of the labeled containers obtained in Examples and Comparative Examples to the container of the label was measured with a measuring instrument (“Autograph AGI-500” manufactured by Shimadzu Corporation) according to JIS Z 0237 (T-type peeling). This was defined as the adhesive strength before immersion. Next, the labeled container was immersed in water at 23 ° C. for 24 hours. Thereafter, the labeled container was taken out of the water, and the adhesive strength was measured in the same manner as the adhesive strength before immersion, and this was defined as the adhesive strength after immersion. And the fall degree of adhesive strength was calculated | required from following formula (3).
Degree of decrease in adhesive strength (%) = ((Adhesive strength before immersion) − (Adhesive strength after immersion)) / (Adhesive strength before immersion) × 100 (3)
And water resistance was evaluated according to the following criteria.
Good (O): Degree of decrease in adhesive strength is less than 50% Poor (X): Degree of decrease in adhesive strength is 50% or more

  As can be seen from Table 1, the labels of the present invention (Examples 1 to 3) were excellent in followability to deformation of the tube container as an adherend and excellent in water resistance. On the other hand, the labels (Comparative Examples 1 and 2) in which the gel fraction (A) of the pressure-sensitive adhesive layer was less than 70% had insufficient water resistance against the tube container as the adherend. Further, the label (Comparative Example 3) in which the gel fraction (B) of the pressure-sensitive adhesive layer exceeds 30% was excellent in water resistance, but the followability to the tube container as the adherend was insufficient. there were.

DESCRIPTION OF SYMBOLS 1 Label of this invention 11 Label base material 12 Printing layer 13 Adhesive layer of this invention 2 Tube container 20 Container main body 21 trunk | drum 22 Sealing part (one side of a trunk | drum)
220 opening 23 spout (the other side of the body)
24 Cap 25 Superposition part 3 Labeled container

Claims (2)

It has a pressure-sensitive adhesive layer formed from a label substrate, a printing layer, and an ultraviolet curable acrylic hot melt pressure-sensitive adhesive,
The pressure-sensitive adhesive layer has a gel fraction (A) defined below of 0 to 30% by weight, and a gel fraction (B) defined below of 70 to 100% by weight. label.
Gel fraction (A): The weight of the pressure-sensitive adhesive layer wrapped with a 100-mesh wire net is measured, and the weight is defined as the weight before immersion (a1). The pressure-sensitive adhesive layer wrapped with a 100-mesh wire mesh was immersed in tetrahydrofuran for 24 hours, then subjected to ultrasonic irradiation for 1 hour, taken out from tetrahydrofuran, dried and removed, and the weight was measured. The weight after immersion is defined as weight (b1). And a gel fraction (A) is calculated | required from following formula (1).
Gel fraction (A) (% by weight) = (weight after immersion (b1) −weight of mesh of 100 mesh) / (weight before immersion (a1) −weight of wire of 100 mesh) × 100 (1)
Gel fraction (B): The weight of the pressure-sensitive adhesive layer wrapped with a 200 mesh wire net is measured, and the weight is defined as the weight before immersion (a2). The pressure-sensitive adhesive layer wrapped with 200 mesh wire mesh was immersed in tetrahydrofuran for 24 hours, then subjected to ultrasonic irradiation for 1 hour, taken out from tetrahydrofuran, dried and removed, and the weight was measured. The weight is defined as the weight after immersion (b2). And a gel fraction (B) is calculated | required from following formula (2).
Gel fraction (B) (% by weight) = (weight after immersion (b2) −weight of wire mesh of 200 mesh) / (weight before immersion (a2) −weight of wire mesh of 200 mesh) × 100 (2)   A labeled container comprising the label according to claim 1.

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