JP6470931B2 - Shrink label - Google Patents

Description

  The present invention relates to a shrink label. More specifically, for example, the present invention relates to a shrink label that is suitable for use in containers such as beverages, foods, toiletries, and pharmaceuticals.

  Currently, plastic bottles such as PET bottles and metal bottles such as bottle cans are widely used as containers for beverages such as tea and soft drinks. These containers are often equipped with plastic labels to give display, decoration, and functionality. For example, because of the merits of decoration, workability (followability to containers), wide display area, etc., shrink Shrink labels or the like in which a printing layer is provided on a film (heat-shrinkable film) are widely used.

  As the shrink label, for example, a shrink label comprising a base film (1) in which an outer surface layer (B1) made of a polyester resin is laminated on both sides of an intermediate layer (A1) made of a polystyrene resin. The polyester-based resin contains 1,4-cyclohexanedimethanol as a diol component, and the outer surface layer (B1) is directly laminated on both sides of the intermediate layer (A1). A shrink label is known (see Patent Document 1). In the shrink label, since the base film is formed by directly laminating an outer surface layer made of a polyester resin on both sides of an intermediate layer made of a polystyrene resin, shrinkage may be inhibited by the adhesive layer. In addition, the advantages of both polystyrene resin and polyester resin, that is, excellent heat resistance, solvent resistance, and low temperature shrinkability, and the process of providing an adhesive layer can be reduced, and a simple method such as a three-layer coextrusion method. Since the base film can be manufactured, it can be easily manufactured at low cost.

JP 2002-351332 A

  The base film having such a composition may be broken when an attempt is made to produce a base film that is stretched further than the stretch normally required for a shrink film. For this reason, the present condition is that the shrink label which has a shrink film of the composition excellent in extending | stretching suitability is calculated | required. In addition, a shrink film having a composition excellent in stretchability often has a soft layer, and is difficult to cut when a shrink label having the shrink film is cut, and the cut suitability is often relatively poor.

  That is, an object of the present invention is to provide a shrink label having a shrink film having a composition excellent in stretchability and relatively excellent in cut suitability. Another object of the present invention is to provide a shrink label having high heat shrinkability.

  That is, this invention is a shrink label which has a shrink film, Comprising: The said shrink film has a base layer part and the surface layer provided in the both surfaces side of the said base layer part, and the said base layer part has 5 layers. A layer (A layer) containing 25 wt% or more of a thermoplastic resin having a glass transition temperature of less than 40 ° C., and a polystyrene resin having a glass transition temperature of 40 ° C. or more are included as layers in the base layer portion. A shrink label comprising at least a layer (B layer) containing 50% by weight or more is provided.

  Moreover, this invention provides the said shrink label whose thermoplastic resin whose glass transition temperature is less than 40 degreeC is a polystyrene resin whose glass transition temperature is less than 40 degreeC.

  Further, in the present invention, the layer A contains 25 to 90% by weight of a thermoplastic resin having a glass transition temperature of less than 40 ° C., a polyester resin having a glass transition temperature of 40 ° C. or higher, and a glass transition temperature of 40 ° C. The shrink label as described above, which is a layer containing 10 to 75% by weight of the above polystyrene resins in total.

  In the present invention, the thickness of the A layer (thickness per layer) is 0.2 to 15 μm, the thickness of the B layer (thickness per layer) is 0.2 to 15 μm, and the thickness of the A layer. Provides the shrink label, wherein (total thickness of all A layers) is less than or equal to the thickness of B layer (total thickness of all B layers).

  Moreover, this invention provides the said shrink label in which the said base layer part contains A layer and B layer alternately as a layer in a base layer part by a total of 5 to 65 layers.

  The shrink label of this invention has the shrink film of the composition which is excellent in stretchability by having the said specific structure. Thereby, when producing the said shrink film, it is hard to fracture | rupture in the process of extending | stretching an unstretched film highly. Further, stretching unevenness can be suppressed, and a stable shrink film having physical properties can be obtained. Furthermore, since the shrink label of this invention is comparatively excellent in cut suitability, when cutting a shrink label, various cutting methods can be employ | adopted.

It is the schematic (partial sectional drawing) which shows an example of the shrink label of this invention. It is the schematic (partial sectional drawing) which shows another example of the shrink label of this invention. It is the schematic (partial sectional drawing) which shows another example of the shrink label of this invention. It is the schematic which shows an example of the cylindrical shrink label which is one Embodiment of the shrink label of this invention. FIG. 5 is a schematic diagram showing an example of a cylindrical shrink label that is an embodiment of the shrink label of the present invention (enlarged view of a main part of the A-A ′ cross section in FIG. 4). It is the schematic which shows an example of a rotary cutter. It is the schematic which shows another example of a rotary cutter.

  The shrink label of the present invention is a shrink label having a shrink film. In the present specification, the shrink film (that is, the shrink film included in the shrink label of the present invention) may be referred to as “the shrink film of the present invention”. The shrink label of this invention may contain layers other than the shrink film of this invention within the range which does not impair the effect of this invention.

[Shrink film]
The shrink film of this invention has a surface layer laminated | stacked on the both surfaces side of the base layer part. That is, the shrink film of the present invention includes a base layer portion and surface layers provided on both sides of the base layer portion. Specifically, the shrink film of the present invention has a layer structure of surface layer / base layer portion / surface layer, and preferably the base layer portion and the surface layer are directly laminated. In the shrink film of the present invention, the surface layers on both sides of the base layer portion may be the same layer or different layers (layers having different resin compositions and layer thicknesses). There may be. In the shrink film of the present invention, an antistatic layer or an anchor coat layer may be provided on the outer surface of the surface layer as long as the effects of the present invention are not impaired. If necessary, the surface of the shrink film of the present invention may be subjected to conventional surface treatment such as corona discharge treatment, primer treatment, and frame treatment.

<Surface layer>
The surface layer in the shrink film of the present invention is a layer (resin layer) provided on each side of the base layer.

  The surface layer is not particularly limited as long as it is a resin layer having shrinkage characteristics and capable of forming a print layer. The resin contained in the surface layer is not particularly limited. For example, polyester resin, polystyrene resin, polyolefin resin (for example, polyethylene resin, polypropylene resin, amorphous cyclic olefin polymer, etc.), Examples thereof include thermoplastic resins such as vinyl chloride resins, polycarbonate resins, polyamide resins, and thermoplastic elastomers. Among these, from the viewpoint of printability of the shrink film, polyester resins, polystyrene resins, amorphous cyclic olefin polymers, and vinyl chloride resins are preferable, and polyester resins and polystyrene resins are more preferable. In view of the property, the polyester resin is particularly preferable. As for the said thermoplastic resin, only 1 type may be used and 2 or more types may be used.

  In the present specification, as the polyester-based resin, for example, a polyester composed of a dicarboxylic acid component and a diol component as essential components (that is, a structural unit (structural unit) derived from dicarboxylic acid and a structural unit derived from diol). Polyester containing at least), polylactic acid polymer, polyester elastomer and the like. Examples of the main polyesters containing at least a structural unit derived from a dicarboxylic acid and a structural unit derived from a diol include a polymer, a copolymer, or a mixture thereof by a condensation reaction of a dicarboxylic acid and a diol.

  Examples of the dicarboxylic acid (dicarboxylic acid component) include terephthalic acid, isophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 5-t-butylisophthalic acid, 4,4′-biphenyldicarboxylic acid, and trans-3. , 3′-stilbene dicarboxylic acid, trans-4,4′-stilbene dicarboxylic acid, 4,4′-dibenzyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,3-naphthalene Dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 2,2,6,6-tetramethylbiphenyl-4,4′-dicarboxylic acid, 1,1,3-trimethyl-3-phenyl Indene-4,5-dicarboxylic acid, 1,2-diphenoxyethane-4,4′-dicarboxylic acid, diphenyl ether Aromatic dicarboxylic acids such as dicarboxylic acid, 2,5-anthracene dicarboxylic acid, 2,5-pyridinedicarboxylic acid, and substituted products thereof; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberin Acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, icosanedioic acid, docosanedioic acid, 1, Aliphatic dicarboxylic acids such as 12-dodecanedioic acid and substituted products thereof; 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid 1,4-decahydronaphthalenedicarboxylic acid, 1,5-decahydronaphth Dicarboxylic acid, 2,6-decahydronaphthalene dicarboxylic acid and an alicyclic dicarboxylic acid such as substituted versions thereof and the like. The said dicarboxylic acid may use only 1 type and may use 2 or more types.

  Examples of the diol (diol component) include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3 -Propanediol, 1,8-octanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2,4-dimethyl-1,3-hexanediol, 1,10-decanediol, Aliphatic diols such as polyethylene glycol and polypropylene glycol; 1,2-cyclohexanedimethanol, , 3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol and other alicyclic diols; 2,2-bis (4-β-hydroxy And ethylene oxide adducts of bisphenol compounds such as ethoxyphenyl) propane and bis (4-β-hydroxyethoxyphenyl) sulfone, and aromatic diols such as xylylene glycol. The diol may be used alone or in combination of two or more.

  In addition to the above, the polyester-based resin includes oxycarboxylic acids such as p-oxybenzoic acid and p-oxyethoxybenzoic acid; monocarboxylic acids such as benzoic acid and benzoylbenzoic acid; and polyvalent carboxylic acids such as trimellitic acid. A structural unit derived from a monohydric alcohol such as polyalkylene glycol monomethyl ether; a polyhydric alcohol such as glycerin, pentaerythritol, or trimethylolpropane;

  Among these, from the viewpoints of rigidity, surface gloss, mechanical strength, heat resistance, heat shrinkability (shrinkage characteristics), and abrasion resistance, the polyester resin is preferably an aromatic polyester resin. The aromatic polyester-based resin means that 50 mol% or more (preferably 70 mol% or more) of the total dicarboxylic acid component is 50 mol% or more (preferably 70 mol% or more of the total diol component). Is a polyester resin whose aromatic diol is 70 mol% or more. Furthermore, the aromatic polyester-type resin which is a polymer by the condensation reaction of the dicarboxylic acid containing aromatic dicarboxylic acid and the diol containing aliphatic diol, or a mixture thereof is preferable.

  The aromatic polyester resin increases the thermal shrinkage rate by making the polyester resin amorphous, and in the case of the polyester resin in the surface layer, delamination between the surface layer and the base layer portion is achieved. From the viewpoint of making it less likely to occur and obtaining a suitable rigidity, a modified aromatic polyester-based resin containing a modifying component (copolymerization component) is preferable, not a single repeating unit. As the modified aromatic polyester resin, for example, at least one of a dicarboxylic acid component and a diol component is composed of two or more components, that is, a modified aromatic polyester resin containing a modified component in addition to the main component. Resins are preferred. In other words, the aromatic polyester-based resin is preferably a modified aromatic polyester-based resin including a structural unit derived from at least two kinds of dicarboxylic acids and / or a structural unit derived from at least two kinds of diols.

  Among the above modified aromatic polyester resins, among the above, in polyethylene terephthalate (PET) using terephthalic acid as the dicarboxylic acid component and ethylene glycol (EG) as the diol component, a part of the dicarboxylic acid component and / or diol component A modified PET in which is replaced with a modified component (that is, another dicarboxylic acid component and / or another diol component) is preferably exemplified.

  Examples of the dicarboxylic acid component used as a modifying component (copolymerization component) of the modified aromatic polyester resin (particularly, modified PET) include cyclohexanedicarboxylic acid, adipic acid, and isophthalic acid. Of these, isophthalic acid is preferable. Examples of the diol component used as the modifying component include 2,2-dialkyl-1,3-propanediol such as 1,4-cyclohexanedimethanol (CHDM) and neopentyl glycol (NPG), and diethylene glycol. Among these, CHDM and 2,2-dialkyl-1,3-propanediol (particularly NPG) are preferable. The alkyl group in the 2,2-dialkyl-1,3-propanediol is preferably an alkyl group having 1 to 6 carbon atoms, and the two alkyl groups may be the same or different. It may be an alkyl group.

  The aromatic polyester-based resin is not particularly limited. Specifically, from the viewpoint of heat shrinkability, polyethylene terephthalate (PET) using terephthalic acid as the dicarboxylic acid component and EG as the diol component; dicarboxylic acid Modified aromatic polyester resin using terephthalic acid as a component, ethylene glycol as a diol component and CHDM as a copolymer component (sometimes referred to as “CHDM copolymerized PET”); terephthalic acid as a dicarboxylic acid component A modified aromatic polyester resin (“2,2-dialkyl-1,3-propane) using ethylene glycol as a main component and 2,2-dialkyl-1,3-propanediol as a copolymerization component. "Diol copolymerized PET" is sometimes preferred) There. Among the 2,2-dialkyl-1,3-propanediol copolymerized PET, in particular, modified fragrance using terephthalic acid as a dicarboxylic acid component, ethylene glycol as a main component as a diol component, and NPG as a copolymerization component. A group polyester resin (sometimes referred to as “NPG copolymerized PET”) is preferred. The aromatic polyester resin is particularly preferably CHDM copolymerized PET and / or 2,2-dialkyl-1,3-propanediol copolymerized PET, and more preferably CHDM copolymerized PET and / or NPG copolymerized PET. Most preferred is CHDM copolymerized PET. Note that copolymer components other than CHDM and 2,2-dialkyl-1,3-propanediol are used for the CHDM copolymerized PET and 2,2-dialkyl-1,3-propanediol copolymerized PET, respectively. For example, isophthalic acid or diethylene glycol may be further copolymerized.

  In the modified aromatic polyester resin, the copolymerization ratio of the copolymer component (modified component) [ratio of the copolymerized dicarboxylic acid component to the total dicarboxylic acid component (ratio), or the ratio of the copolymerized diol component to the total diol component ( The ratio)] is not particularly limited, but is preferably 10 mol% or more (for example, 10 to 40 mol%), more preferably 15 mol% or more from the viewpoint of optimizing the thermal deformation behavior of the layer and reducing delamination. (For example, 15 to 40 mol%). Among them, for example, in the case of CHDM copolymerized PET, the proportion of CHDM is preferably 10 mol% or more (EG is 90 mol% or less), more preferably 12 mol% or more (EG is 88 mol% or less) in all diol components. ), More preferably 15 mol% or more (EG is 85 mol% or less), 20 mol% or more (EG is 80 mol% or less), and 25 mol% or more (EG is 75 mol% or less). . Further, the upper limit of the ratio of CHDM is preferably 40 mol% or less (EG is 60 mol% or more), more preferably 35 mol% or less (EG is 65 mol% or more), further preferably 30 mol in all diol components. % Or less (EG is 70 mol% or more), particularly preferably 25 mol% or less (EG is 75 mol% or more). In the case of 2,2-dialkyl-1,3-propanediol copolymerized PET, the ratio of 2,2-dialkyl-1,3-propanediol (the ratio of NPG in the case of NPG copolymerized PET) is In the diol component, 10 mol% or more (EG is 90 mol% or less) is preferable, and more preferably 15 mol% or more (EG is 85 mol% or less). Moreover, the upper limit of the ratio of NPG is preferably 40 mol% or less (EG is 60 mol% or more), more preferably 30 mol% or less (EG is 70 mol% or more) in all diol components. Further, a part of the EG component (preferably 1 to 30 mol%, more preferably 1 to 10 mol% in all diol components) may be replaced with diethylene glycol.

  The aromatic polyester resin is preferably a substantially amorphous aromatic polyester resin, more preferably an aromatic polyester resin that is an amorphous saturated polyester resin. Although not particularly limited, the aromatic polyester-based resin becomes difficult to crystallize by being modified as described above, and can be made substantially amorphous by, for example, modification. By making the aromatic polyester-based resin amorphous, extrusion at a relatively low temperature becomes possible. Thereby, in the case of the polyester-based resin in the surface layer, delamination is less likely to occur between the surface layer and the base layer portion, because the layer formability of the surface layer at the time of extrusion processing is improved, Shrink label shrinkage characteristics are improved.

  The degree of crystallinity of the polyester resin measured by a differential scanning calorimetry (DSC) method (measured at a heating rate of 10 ° C./min) is preferably 15% or less, more preferably 10% or less. Further, the polyester-based resin is most preferably one having almost no melting point (melting peak) when measured by the DSC method (that is, a crystallinity of 0%). The crystallinity can be calculated from the value of heat of crystal fusion obtained by DSC measurement, with a sample having a clear crystallinity measured by the X-ray method or the like as a standard. The heat of crystal melting is, for example, using a DSC (Differential Scanning Calorimetry) device manufactured by Seiko Instruments Inc. and performing a nitrogen seal at a sample amount of 10 mg and a heating rate of 10 ° C./min. It can be determined from the area of the melting peak when the temperature is raised to room temperature and then raised again. The crystallinity is preferably measured from a single resin, but when measured in a mixed state, the melting peak of the target polyester resin can be obtained by subtracting the melting peak of the resin to be mixed. That's fine.

  The weight average molecular weight (Mw) of the polyester-based resin is preferably 15,000 to 100,000, more preferably 15,000 to 90,000, and still more preferably 30,000 to 10,000, from the viewpoint of melting behavior and shrinkage behavior. 90,000, particularly preferably 30,000 to 80,000. In the case of 2,2-dialkyl-1,3-propanediol copolymerized PET, 50,000 to 70,000 is particularly preferable. In addition, in this specification, although a weight average molecular weight (Mw) is not specifically limited, For example, it can measure by GPC using polystyrene as a standard substance.

  The glass transition temperature (Tg) of the polyester resin is preferably 60 to 80 ° C., more preferably 60 to 75 ° C. from the viewpoints of stretching characteristics and shrinkage characteristics. The Tg can be controlled by the type of dicarboxylic acid or diol constituting the polyester resin and the copolymerization ratio of the copolymerization component (modification component) used for modification.

  Commercially available products may be used as the polyester resin. For example, “EMBRACE 21214”, “EMBRACE LV” (CHDM copolymerized PET) manufactured by Eastman Chemical (Eastman Chemical), Bell Polyester Products, Inc. “Belpet MGG200” (2,2-dialkyl-1,3-propanediol copolymerized PET) manufactured by Bellpet Products, “Belpet E02” (NPG copolymerized PET) manufactured by Bell Polyester Products, Inc. is available on the market.

  The polylactic acid-based polymer means a polymer containing lactic acid (D-lactic acid, L-lactic acid, DL-lactic acid, or a mixture thereof) as a monomer component, and lactic acid and other monomer components (for example, , Copolymers with other hydroxycarboxylic acids, lactones, dicarboxylic acids, diols, and the like). Other hydroxycarboxylic acids include, for example, glycolic acid, 2-methyllactic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxy-3,3-dimethyl Examples include butyric acid and 2-hydroxycaproic acid. Examples of the lactone include γ-butyrolactone, δ-valerolactone, and ε-caprolactone. Moreover, as dicarboxylic acid, the dicarboxylic acid illustrated and demonstrated as a component which comprises the above-mentioned polyester-type resin, etc. are mentioned. Examples of the diol include diols exemplified and described as components constituting the above-described polyester resin. These other monomer components may be mixed with lactic acid in a monomer state and may be introduced into the polymer as a random copolymer, or oligomers polymerized in advance as polyester, or lactic acid and block copolymer as a prepolymer. It may be introduced into the polymer in the form of a polymer.

  The composition ratio of optical isomers of lactic acid constituting the polylactic acid-based polymer (content ratio of D-form and L-form) varies depending on the required physical properties and is not particularly limited, but from the viewpoint of crystallinity control The ratio of D-lactic acid to the total lactic acid component is 1 to 20% by weight (preferably 1 to 15% by weight), or the ratio of L-lactic acid to the total lactic acid component is 1 to 20% by weight (preferably 1 to 15% by weight). Especially, the case where the ratio of D-lactic acid with respect to all the lactic acid components is 1 to 20 weight% is more preferable.

  The ratio of lactic acid in the total monomers constituting the polylactic acid polymer is not particularly limited, but is preferably 50 mol% or more, more preferably 65 mol% or more, and further preferably 80 mol% or more. Although the upper limit of the said ratio is not specifically limited, 100 mol% may be sufficient. The said polylactic acid-type polymer may use only 1 type, and may use 2 or more types. For example, two or more polylactic acid polymers having different ratios of L-lactic acid and D-lactic acid can be used in combination.

  The polylactic acid-based polymer can be produced, for example, by polymerizing lactic acid produced using starch obtained from corn, moss or the like as a raw material. The polymerization method is not particularly limited, and a known or conventional method such as a condensation polymerization method or a ring-opening polymerization method can be employed. For example, in the polycondensation method, lactic acid or a polylactic acid polymer having an arbitrary composition can be obtained by directly dehydrating condensation of lactic acid and other monomer components. In the ring-opening polymerization method, lactide, which is a cyclic dimer of lactic acid, is polymerized in the presence of a suitable catalyst to obtain a polylactic acid polymer having an arbitrary composition.

  The weight average molecular weight (Mw) of the polylactic acid polymer is not particularly limited, but is usually about 5,000 to 100,000, preferably about 10,000 to 50,000, from the viewpoint of mechanical properties and melt viscosity. . If the weight average molecular weight is too small, the mechanical properties and heat resistance may be inferior. If the weight average molecular weight is too large, moldability may be reduced.

  In the present specification, the polystyrene resin is a polymer composed of a styrene monomer as an essential monomer component. That is, it is a polymer containing at least a structural unit derived from a styrene monomer in the molecule (in one molecule).

  Although it does not specifically limit as said styrene-type monomer, For example, styrene, alpha-methyl styrene, m-methyl styrene, p-methyl styrene, p-ethyl styrene, p-isobutyl styrene, pt-butyl styrene, Examples include chloromethylstyrene. Among these, styrene is preferable from the viewpoint of availability, material price, and the like. In addition, the said styrene-type monomer may use only 1 type, and may use 2 or more types.

  The polystyrene resin is not particularly limited. For example, a homopolymer of a styrene monomer such as general-purpose polystyrene (GPPS) that is a homopolymer of styrene; only two or more styrene monomers are used alone. Copolymer constituted as a monomer component; styrene-diene copolymer; copolymer such as styrene-polymerizable unsaturated carboxylic acid ester copolymer; polystyrene and synthetic rubber (for example, polybutadiene, polyisoprene, etc.) ), High-impact polystyrene (HIPS) such as polystyrene obtained by graft-polymerizing styrene to synthetic rubber; polymers containing styrene monomers (for example, styrene monomers and (meth) acrylic acid ester monomers) A rubber-like elastic body is dispersed in a continuous phase of a copolymer with a polymer, and the copolymer is graft-polymerized on the rubber-like elastic body. Styrene (referred graft type high impact polystyrene "graft HIPS"); and styrene elastomers. Among the polystyrene resins, styrene-diene copolymers are preferable. In addition, the said polystyrene type resin may use only 1 type, and may use 2 or more types.

  The styrene-diene copolymer is a copolymer composed of styrene monomers and dienes (particularly conjugated dienes) as essential monomer components. That is, it is a polymer containing at least a structural unit derived from a styrene monomer and a structural unit derived from a diene (particularly conjugated diene) in the molecule (in one molecule).

  The diene is not particularly limited, but is preferably a conjugated diene, such as 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, 1, Examples include 3-pentadiene, 1,3-hexadiene, chloroprene. Among these, 1,3-butadiene is particularly preferable. That is, the styrene-diene copolymer is preferably a styrene-butadiene copolymer. In addition, the said diene may use only 1 type and may use 2 or more types.

  The monomer component constituting the styrene-diene copolymer may further contain a monomer component other than the styrene monomer and the diene. Examples of monomer components other than the styrene monomer and the diene include vinyl monomers, polymerizable unsaturated carboxylic acid esters, and polymerizable unsaturated carboxylic anhydrides.

  The form of copolymerization of the styrene-diene copolymer is not particularly limited, and examples thereof include random copolymers, block copolymers, and graft copolymers. Among these, block copolymers are preferable, and examples thereof include styrene block (S) -diene block (D) type, SDS type, DSD type, SSDSD type, and the like. .

  Examples of the styrene-diene copolymer block copolymer (styrene-diene block copolymer) include styrene-butadiene block copolymers such as styrene-butadiene-styrene block copolymer (SBS), styrene, and the like. -Styrene-isoprene block copolymers such as isoprene-styrene block copolymer (SIS), and styrene-butadiene-isoprene block copolymers such as styrene-butadiene / isoprene-styrene block copolymer (SBIS). Of these, styrene-butadiene block copolymers are preferred. In addition, these block copolymers may use only 1 type and may use 2 or more types.

  The styrene-butadiene block copolymer is not particularly limited as long as it is a copolymer having alternately a styrene block obtained by polymerizing only a styrene monomer and a butadiene block obtained by polymerizing only butadiene. A styrene-butadiene block copolymer having styrene blocks at both ends, such as a butadiene-styrene block copolymer (SBS) and a styrene-butadiene-styrene-butadiene-styrene block copolymer (SBSBS); Styrene block and styrene-butadiene block copolymer having a butadiene block at each end; butadiene-styrene-butadiene copolymer (B), such as polymer (SB) and styrene-butadiene-styrene-butadiene copolymer (SBSB) B), butadiene - styrene - butadiene - styrene - butadiene block copolymer, and the like - styrene with butadiene copolymer (BSBSB) butadiene block such at both ends. Among these, a styrene-butadiene block copolymer having a styrene block at both ends is preferable, and SBS is more preferable. In addition, these styrene-butadiene block copolymers may use only 1 type, and may use 2 or more types.

  The styrene-diene block copolymer can be produced by a known or conventional method for producing a block copolymer. Examples of the method for producing the styrene-diene block copolymer include living polymerization (living radical polymerization, living anion polymerization, living cation) that can easily control the molecular weight, molecular weight distribution, terminal structure and the like of the styrene-diene block copolymer. Polymerization). The living polymerization can be carried out by a known or conventional method.

  The polystyrene resin is not particularly limited, but may be hydrogenated. That is, the polystyrene resin may be a hydrogenated polystyrene resin (hydrogenated polystyrene resin). The hydrogenated polystyrene resin is not particularly limited, but hydrogenated styrene-butadiene-styrene block copolymer (SEBS) or hydrogenated styrene-isoprene-styrene block copolymer which is a resin obtained by adding hydrogen to SBS or SIS. Hydrogenated styrene-diene copolymers such as coalesced (SEPS) are preferred. The hydrogenated polystyrene resin may be used alone or in combination of two or more.

  Moreover, although the said polystyrene-type resin is not specifically limited, The polar group may be introduce | transduced. That is, the polystyrene resin may be a polystyrene resin into which a polar group has been introduced (modified polystyrene resin). The modified polystyrene resin includes a hydrogenated polystyrene resin into which a polar group has been introduced.

  The modified polystyrene resin is a polystyrene resin in which a polar group is introduced using a polystyrene resin as a main chain skeleton. The polar group is not particularly limited, and examples thereof include an acid anhydride group, a carboxylic acid group, a carboxylic acid ester group, a carboxylic acid chloride group, a carboxylic acid amide group, a carboxylic acid group, a sulfonic acid group, and a sulfonic acid ester group. Sulfonic acid chloride group, sulfonic acid amide group, sulfonic acid group, isocyanate group, epoxy group, amino group, imide group, oxazoline group, hydroxyl group and the like. Among these, an acid anhydride group, a carboxylic acid group, a carboxylic acid ester group, and an epoxy group are preferable, and a maleic anhydride group and an epoxy group are more preferable. As for the said polar group, only 1 type may be used and 2 or more types may be used.

  Although it does not specifically limit as said modified polystyrene resin, The modified body of hydrogenated styrene-butadiene-styrene block copolymer (SEBS) and the modified body of hydrogenated styrene-propylene-styrene block copolymer (SEPS) are preferable. . That is, the modified polystyrene resin is not particularly limited, but acid anhydride-modified SEBS, acid anhydride-modified SEPS, epoxy-modified SEBS, and epoxy-modified SEPS are preferable, and maleic anhydride-modified SEBS and maleic anhydride are more preferable. Modified SEPS, epoxy-modified SEBS, and epoxy-modified SEPS. Only 1 type may be used for the said modified polystyrene resin, and 2 or more types may be used for it.

  Commercially available products may be used as the polystyrene-based resin. For example, “Clearen 530L”, “Clearen 730L” manufactured by Denki Kagaku Kogyo Co., Ltd., “Tufrene 126S”, “Asaprene T411” manufactured by Asahi Kasei Co., Ltd., Kraton Polymer “Clayton D1102A”, “Clayton D1116A” manufactured by Japan Co., Ltd., “Styrolux S”, “Styrolux T” manufactured by Stylorusion Corporation, “Asaflex 840”, “Asaflex 860” manufactured by Asahi Kasei Chemicals Corporation Above, SBS), PS Japan Co., Ltd. “679”, “HF77”, “SGP10”, DIC Corporation “Dick Styrene XC-515”, “Dick Styrene XC-535” (above, GPPS), PS “475D”, “H0103”, “ T478 ", DIC (Ltd.)" Dick styrene GH-8300-5 "(or more, HIPS) and the like. Examples of the hydrogenated polystyrene resin include “Tuff Tech H Series” manufactured by Asahi Kasei Chemicals Corporation, “Clayton G Series” manufactured by Shell Japan Co., Ltd. (hereinafter referred to as SEBS), and “Dynalon” manufactured by JSR Corporation (hydrogenated). Styrene-butadiene random copolymer), “Septon” (SEPS) manufactured by Kuraray Co., Ltd., and the like. Examples of modified polystyrene resins include “Tuftec M Series” manufactured by Asahi Kasei Chemicals Corporation, “Epofriend” manufactured by Daicel Corporation, “Polar Group Modified Dynalon” manufactured by JSR Corporation, and Toagosei Co., Ltd. "Reseda" made by the company.

  As the polystyrene resin that may be contained in the surface layer, among them, from the viewpoint of shrinkage characteristics of the shrink label and interlayer strength, a styrene-diene copolymer is preferable, and a styrene-butadiene copolymer is more preferable. More preferred is a styrene-butadiene block copolymer, particularly preferred is a styrene-butadiene block copolymer having styrene blocks at both ends, and most preferred is SBS.

  The styrene-diene copolymer as the polystyrene resin that may be contained in the surface layer is not particularly limited, but the content of the constituent unit derived from the styrene monomer is such that the content of the styrene-diene copolymer is not limited. It is preferably 50 to 95% by weight, more preferably 60 to 90% by weight, still more preferably 70 to 90% by weight, particularly preferably 75 to 90% by weight, based on the total weight (100% by weight) of the polymer. . When the content is 50% by weight or more, the shrink film is suitably hardened, the rigidity of the shrink label is moderately high, and the shrinkage property when the shrink label is attached is good, which is preferable. It is preferable for the content to be 95% by weight or less because appropriate shrinkage stress and shrinkage characteristics can be obtained.

  The styrene-diene copolymer as a polystyrene resin that may be contained in the surface layer is not particularly limited, but the content of structural units derived from diene is the total of the styrene-diene copolymer. It is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, still more preferably 10 to 30% by weight, and particularly preferably 10 to 25% by weight based on the weight (100% by weight). When the content is 50% by weight or less, the shrink film is appropriately hardened, the rigidity of the shrink label is appropriately increased, and the shrinkage property when the shrink label is attached is favorable, which is preferable. It is preferable for the content to be 5% by weight or more because appropriate shrinkage stress and shrinkage characteristics can be obtained.

  When the styrene-diene copolymer contained in the layer contains two or more styrene-diene copolymers, the content of the structural unit derived from the styrene monomer and the diene The content of the structural unit is the content in all styrene-diene copolymers.

In this specification, the content of the structural unit derived from the styrene monomer and the content of the structural unit derived from the diene are the composition of the styrene-diene copolymer (in each styrene-diene copolymer). And the content of each styrene-diene copolymer in all styrene-diene copolymers contained in the layer). More specifically, for example, in the styrene-diene copolymer, the content of the structural unit derived from the styrene monomer is s ₁ (% by weight) and the content of the structural unit derived from the diene is d. ₁ (% by weight) of the styrene-diene copolymer (PS1) and the content of the structural unit derived from the styrene monomer is s ₂ (% by weight) and the content of the structural unit derived from the diene. It is a resin mixture composed only of a styrene-diene copolymer (PS2) that is d ₂ (% by weight), and the content of PS1 in 100% by weight of the above resin mixture (resin mixture of PS1 and PS2) is W ₁ (wt%), when the content of PS2 is W ₂ (wt%), the content of constituent units derived from the content and diene constituent units derived from the styrene monomer of the resin mixture The amount is generally controlled as follows Kill.
Content (% by weight) of structural unit derived from styrenic monomer = (s ₁ × W ₁ + s ₂ × W ₂ ) / 100
Content (% by weight) of structural unit derived from diene = (d ₁ × W ₁ + d ₂ × W ₂ ) / 100

  The analysis / measurement of the content of the structural unit (the structural unit derived from a styrene monomer and the structural unit derived from a diene) and the content of the structural unit is not particularly limited. For example, nuclear magnetic resonance (NMR), gas chromatograph It can be performed by a tomograph mass spectrometer (GCMS) or the like. In addition, the analysis / measurement of the constituent unit in the layer or the resin and the content of the constituent unit can be performed in the same manner.

  In this specification, examples of the polyolefin resin include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), metallocene catalyst system LLDPE (mLLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene, and the like. -A polymer composed of ethylene as an essential monomer component, such as a (meth) acrylate copolymer (polyethylene resin); A polymer composed of propylene as an essential monomer component (polypropylene resin) Ionomer; amorphous cyclic olefin polymer; olefin elastomer and the like. Among these, from the viewpoint of printability, an amorphous cyclic olefin polymer is preferable.

  Examples of the amorphous cyclic olefin polymer include a copolymer of an α-olefin such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and at least one cyclic olefin. (Sometimes referred to as "cyclic olefin copolymer") and cyclic olefin ring-opening polymer or hydrogenated product thereof (sometimes referred to as "cyclic olefin ring-opening polymer or hydrogenated product thereof") Is mentioned. The cyclic olefin copolymer, the cyclic olefin ring-opening polymer, or the hydrogenated product thereof also includes a graft-modified product thereof.

Examples of the cyclic olefin used in the amorphous cyclic olefin-based polymer include bicyclo [2.2.1] hept-2-ene (norbornene), tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, hexacyclo [6.6.1.1 ^3,6 . 1 ^10,13 . 0 ^2,7 . 0 ^9,14] -4-heptadecene, octacyclo [8.8.0.1 ^2,9. 1 ^4,7 . 1 ^11,18 . 1 ^13,16 . 0 ^3,8 . 0 ^12,17 ] -5-docosene, pentacyclo [6.6.1.1 ^3,6 . 0 ^2,7 . 0 ^9,14] -4-hexadecene, heptacyclo-5-icosene, heptacyclo-5-henicosenoic, tricyclo [4.3.0.1 ^{2, 5]-3-decene,} tricyclo [4.4.0.1 ^{2 , 5} ] -3-undecene, pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ] -4-pentadecene, pentacyclopentadecadiene, pentacyclo [4.7.0.1 ^2,5 . 0 ^8,13 . 1 ^9,12] -3-pentadecene, Nonashikuro [9.10.1.1 ^{4, 7.} 1 ^13,20 . 1 ^15,18 . 0 ^2,10 . 0 ^12,21 . 0 ^14,19] -5-pentacosene and the like polycyclic olefins such. Of these, norbornene is preferable. These cyclic olefins may have substituents such as ester groups such as methoxycarbonyl and ethoxycarbonyl groups, alkyl groups such as methyl groups, haloalkyl groups, cyano groups, and halogen atoms in the ring.

  The cyclic olefin copolymer is, for example, the α-olefin and the cyclic olefin in hydrocarbon solvents such as hexane, heptane, octane, cyclohexane, benzene, toluene, xylene, so-called Ziegler catalyst, metallocene catalyst, etc. It can be obtained by polymerization using a catalyst. Such cyclic olefin copolymers are commercially available, and for example, “Apel” manufactured by Mitsui Chemicals, Inc., “TOPAS” manufactured by Polyplastics Co., Ltd., and the like can be used.

  The ring-opening polymer of the cyclic olefin or the hydrogenated product thereof is usually obtained by subjecting one or more of the cyclic olefins to metathesis polymerization (ring-opening polymerization) using a molybdenum compound or a tungsten compound as a catalyst. The polymer obtained can be further hydrogenated. Such ring-opened polymers of cyclic olefins or hydrogenated products thereof are commercially available. For example, “Arton” manufactured by JSR Corporation, “Zeonex” manufactured by Nippon Zeon Co., Ltd., “Zeonor”, and the like can be used.

  The amorphous cyclic olefin polymer is not particularly limited, but a cyclic olefin copolymer is more preferable. When the polyolefin resin is mixed, the cyclic olefin copolymer has a high compatibility and compatibility with the polyolefin resin, and a shrink film excellent in transparency and impact resistance can be obtained.

  The glass transition temperature (Tg) of the amorphous cyclic olefin-based polymer is not particularly limited, but is preferably 50 to 80 ° C, more preferably 60 to 80 ° C, and still more preferably 60 to 75 from the viewpoint of stretchability. It is 65 degreeC, Most preferably, it is 65-75 degreeC (especially about 70 degreeC). The glass transition temperature of the amorphous cyclic olefin-based polymer can be adjusted by the type of monomer component (for example, cyclic olefin) and the blending ratio thereof.

  When the amorphous cyclic olefin polymer is a cyclic olefin copolymer, the content of the structural unit derived from the cyclic olefin (for example, norbornene) in the cyclic olefin copolymer is not particularly limited. From the viewpoint of shrinkability, it is preferably 50 to 75% by weight, more preferably 60 to 70% by weight, based on the total weight (100% by weight) of the cyclic olefin copolymer and the like. For example, the norbornene content in the cyclic olefin copolymer is preferably in the above range.

  The surface layer is not particularly limited, but a layer containing 50% by weight or more of the thermoplastic resin is preferable, more preferably 70% by weight or more, still more preferably 80% by weight or more, and particularly preferably 90% by weight or more. Preferably it is 95 weight% or more. The upper limit of the content may be 100% by weight. When a plurality of thermoplastic resins are included in the surface layer, the content of the thermoplastic resin is the sum of the contents of all the thermoplastic resins included in the surface layer.

  The surface layer is preferably a layer containing 50% by weight or more of a thermoplastic resin as a main component, more preferably 55% by weight or more, further preferably 60% by weight or more, and further preferably 70% by weight. Above, particularly preferably 80% by weight or more, most preferably 90% by weight or more. The upper limit of the content may be 100% by weight. The surface layer is more preferably a layer in which the content of the polyester resin or polystyrene resin is in the above range, and a layer in which the content of the polyester resin is in the above range is particularly preferable. In this case, a shrink label having high heat shrinkability can be obtained, which is preferable.

  The surface layer is within the range not impairing the effects of the present invention, and includes lubricants, fillers, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, antifogging agents, flame retardants, colorants, pinning agents ( An additive such as an alkaline earth metal) or a compatibilizing agent may be contained.

<Base layer part>
The base layer part in the shrink film of the present invention includes 5 to 65 layers. In addition, the base layer portion includes, as a layer in the base layer portion, a layer (A layer) containing 25% by weight or more of a thermoplastic resin having a glass transition temperature of less than 40 ° C., and a polystyrene system having a glass transition temperature of 40 ° C. or more. It has at least a layer (B layer) containing 50% by weight or more of resin. By providing the base layer portion, the shrink film of the present invention is excellent in stretchability. In addition, in this specification, the notation which connected the number with the wavy line like "5-65" shows the range including the numerical value of the both ends like "5 or more and 65 or less".

  In the present specification, the “base layer portion” is a portion sandwiched between the surface layers in the shrink film of the present invention. The base layer portion has a structure in which 5 to 65 layers are laminated, and is a layer of the base layer portion, two outermost layers located on both end surfaces in the thickness direction, and a thickness sandwiched between the outermost layers. It is comprised by the some intermediate | middle layer located in a direction inner side. That is, the base layer portion has a configuration of [outermost layer / intermediate layer /... / Intermediate layer / outermost layer].

  In the present specification, the “layer containing 25% by weight or more of a thermoplastic resin having a glass transition temperature of less than 40 ° C.” may be referred to as “A layer”. In the present specification, the “layer containing 50% by weight or more of a polystyrene resin having a glass transition temperature of 40 ° C. or higher” may be referred to as “B layer”. That is, the base layer portion includes at least an A layer and a B layer. The A layer and the B layer are layers having different raw material compositions, and the B layer does not include a layer containing 25% by weight or more of a thermoplastic resin having a glass transition temperature of less than 40 ° C. When there are a plurality of A layers in the base layer portion, all or some of the plurality of A layers may be the same layer or within the range of the A layer defined in the present application. Different layers (layers having different resin compositions and layer thicknesses) may be used. Similarly, when there are a plurality of B layers in the base layer portion, all or some of the plurality of B layers may be the same layer, or the B layer defined in the present application. The layers may be different from each other within the range (layers having different resin compositions and layer thicknesses). The said base layer part may contain layers (other layers) other than A layer and B layer in the range which does not impair the effect of this invention. Further, each of the A layer and the B layer may be an outermost layer of the base layer portion, an intermediate layer, or both may be included in the base layer portion.

  In the base layer portion, the layers in the adjacent base layer portions have different raw material compositions. This is because, if the raw material compositions of the layers in the adjacent base layer portions are the same, the interface between adjacent layers in the base layer portion is not visible and overlaps to form one layer.

  The layer in the base layer part is a resin layer. The resin layer should just contain the thermoplastic resin at least. The content of the thermoplastic resin in the resin layer is not particularly limited, but is preferably 50% by weight or more, more preferably 70% by weight or more, and still more preferably 90% by weight based on the total weight (100% by weight) of the resin layer. % Or more, particularly preferably 95% by weight or more.

  The thermoplastic resin is not particularly limited. For example, polyester resin, polystyrene resin, polyolefin resin, vinyl chloride resin, polycarbonate resin, polyamide resin, thermoplastic elastomer, acrylic resin, urethane resin. And vinyl acetate resin.

  Although the layer in the said base layer part is not specifically limited, From a viewpoint of the heat shrinkable improvement of a shrink film, the polymer plasticizer may be included. Examples of the polymer plasticizer include 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 resins, etc.), petroleum resins (aliphatic petroleum resins, aromatic petroleum resins, alicyclic petroleum resins) and the like. Among these, petroleum resin is preferable. Only 1 type may be used for the said polymeric plasticizer, and 2 or more types may be used for it. As the polymer plasticizer, “Arcon” manufactured by Arakawa Chemical Industry Co., Ltd., “Clearon” manufactured by Yashara Chemical Co., Ltd., “Imabe” manufactured by Idemitsu Kosan Co., Ltd., etc. are commercially available.

  The layer in the base layer part may contain other components (additional components) as necessary, for example, lubricants, fillers, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, antifogging agents, flame retardants. , Coloring agents, pinning agents (alkaline earth metals), softeners, compatibilizers, and the like may be included. These components may use only 1 type and may use 2 or more types. Moreover, the layer in the said base layer part may contain the collection | recovery raw material (recycled material) in the range which does not impair the effect of this invention. The recovered material is a recycled material composed of non-product parts before and after commercialization, film edges, etc., remaining parts when product films are collected from intermediate products, non-standard product film scraps, and polymer scraps. However, the recovered raw material is preferably a product (so-called self-recovered product) produced from the production of the shrink film of the present invention.

(A layer)
A layer is a layer which contains 25 weight% or more of thermoplastic resins whose glass transition temperature (Tg) is less than 40 degreeC in a layer. In the present specification, the “thermoplastic resin having a glass transition temperature of less than 40 ° C.” may be referred to as a “specific thermoplastic resin”.

  The glass transition temperature of the said specific thermoplastic resin is less than 40 degreeC, Preferably it is 30 degrees C or less, More preferably, it is 20 degrees C or less. Moreover, the minimum of the said glass transition temperature is although it does not specifically limit, -100 degreeC is preferable, More preferably, it is -90 degreeC, More preferably, it is -80 degreeC. When the glass transition temperature of the specific thermoplastic resin is less than 40 ° C., the stretchability of the shrink film is excellent.

  In the present specification, the glass transition temperature (Tg) of the resin can be measured by DSC (differential scanning calorimetry) in accordance with, for example, JIS K7121. The DSC measurement is not particularly limited. For example, the DSC measurement can be performed using a differential scanning calorimeter “DSC6200” manufactured by Seiko Instruments Inc. under a temperature rising rate of 10 ° C./min.

  The specific thermoplastic resin is not particularly limited as long as the glass transition temperature is less than 40 ° C. For example, polyester resin, polystyrene resin, polyolefin resin, vinyl chloride resin, polycarbonate resin, polyamide resin, heat Examples thereof include thermoplastic resins such as plastic elastomers. Of these, polystyrene resins, polyester resins, and polyolefin resins are preferable, and polystyrene resins are more preferable.

  Examples of the polystyrene resin having a glass transition temperature of less than 40 ° C. include those having a glass transition temperature of less than 40 ° C. among the polystyrene resins exemplified and described as polystyrene resins that may be contained in the surface layer. . Specific examples of polystyrene resins having a glass transition temperature of less than 40 ° C. include styrene elastomers, styrene-diene copolymers, modified polystyrene resins, HIPS (high impact polystyrene), and grafted HIPS. It is done. Of these, styrene elastomers and styrene-diene copolymers are preferable. The polystyrene-type resin whose glass transition temperature is less than 40 degreeC may use only 1 type, and may use 2 or more types. Further, the polystyrene resins having a glass transition temperature of less than 40 ° C. may overlap each other. For example, the styrene elastomer may be a styrene-diene copolymer. The styrene elastomer may contain a diene component and may be a styrene-diene copolymer elastomer. In addition, although HIPS as said specific thermoplastic resin is not specifically limited, HIPS over 30 weight% with respect to the total weight (100 weight%) of a rubber component is preferable. The graft HIPS as the specific thermoplastic resin is not particularly limited, but a graft HIPS in which the content of the rubber component exceeds 30% by weight with respect to the total weight (100% by weight) of the graft HIPS is preferable.

  Although it does not specifically limit as a styrene-type monomer of the monomer component which comprises the styrene-diene type copolymer as the said specific thermoplastic resin, A styrene is preferable. Although it does not specifically limit as diene of the monomer component which comprises the said styrene diene type copolymer, A conjugated diene is preferable and 1, 3- butadiene is especially preferable.

  The form of copolymerization of the styrene-diene copolymer as the specific thermoplastic resin is not particularly limited, but among these, block copolymers are preferable, styrene-butadiene block copolymers are more preferable, and styrene is more preferable. A styrene-butadiene block copolymer having blocks at both ends, particularly preferably SBS.

  The styrene-diene copolymer as the specific thermoplastic resin is not particularly limited, but the content of the structural unit derived from the styrene monomer is the total weight of the styrene-diene copolymer (100% by weight). ) Is preferably 50 to 95% by weight, more preferably 60 to 90% by weight, still more preferably 70 to 90% by weight, and particularly preferably 75 to 90% by weight. In addition, the styrene-diene copolymer as the specific thermoplastic resin is not particularly limited, but the content of the structural unit derived from diene is the total weight (100% by weight) of the styrene-diene copolymer. On the other hand, 5 to 50 weight% is preferable, More preferably, it is 10 to 40 weight%, More preferably, it is 10 to 30 weight%, Especially preferably, it is 10 to 25 weight%.

  The glass transition temperature of the styrene-diene copolymer as the specific thermoplastic resin is, for example, the content of a structural unit derived from a styrene monomer in the styrene-diene copolymer or a configuration derived from a diene. It can be adjusted according to the unit content, the molecular structure of the styrene-diene copolymer, the bonding state, and the like.

  In the styrene-diene copolymer elastomer as the specific thermoplastic resin, the content of the structural unit derived from diene is 50% by weight with respect to the total weight (100% by weight) of the styrene-diene copolymer. The above styrene-diene copolymer is preferable, more preferably 60 to 95% by weight, still more preferably 65 to 90% by weight. The content of the structural unit derived from the styrene monomer is preferably 50% by weight or less of the styrene-diene copolymer with respect to the total weight (100% by weight) of the styrene-diene copolymer. More preferably, it is 5 to 40% by weight, and further preferably 10 to 35% by weight.

  As the polystyrene resin having a glass transition temperature of less than 40 ° C., commercially available products may be used. For example, “Septon” manufactured by Kuraray Co., Ltd. “Tufprene” manufactured by Asahi Kasei Co., Ltd. “Tuftec” manufactured by Asahi Kasei Chemicals Co., Ltd. Are available on the market.

  Examples of the polyester resin having a glass transition temperature of less than 40 ° C. include those having a glass transition temperature of less than 40 ° C. among the polyester resins exemplified and described as the polyester resin that may be contained in the surface layer. It is done. Specifically, as a polyester resin having a glass transition temperature of less than 40 ° C., for example, a polyester composed of a dicarboxylic acid component and a diol component as essential components (that is, a structural unit derived from dicarboxylic acid (structural unit) ) And a polyester containing at least a structural unit derived from diol), polyester elastomers, polylactic acid polymers, and the like. Of these, polyester elastomers are preferred.

  As the polyester resin having a glass transition temperature of less than 40 ° C., commercially available products may be used. For example, “Hytrel” manufactured by Toray DuPont Co., Ltd. and “Primalloy” manufactured by Mitsubishi Chemical Co., Ltd. are available on the market. .

  Examples of the polyolefin resin having a glass transition temperature of less than 40 ° C. include those having a glass transition temperature of less than 40 ° C. among the polyolefin resins exemplified and described as the polyolefin resin that may be contained in the surface layer. It is done. Specific examples of polyolefin resins having a glass transition temperature of less than 40 ° C. include polyethylene resins, polypropylene resins, amorphous cyclic olefin polymers, and olefin elastomers. Of these, olefin-based elastomers are preferable.

  As the polyolefin resin having a glass transition temperature of less than 40 ° C., a commercially available product may be used. For example, “Zeras” manufactured by Mitsubishi Chemical Corporation can be obtained on the market.

  The content of the thermoplastic resin (specific thermoplastic resin) having a glass transition temperature of less than 40 ° C. in the layer A is 25% by weight or more based on the total weight (100% by weight) of the layer A, preferably It is 30% by weight or more, more preferably 35% by weight or more, and further preferably 40% by weight or more. The upper limit of the content may be 100% by weight. If the content is less than 25% by weight, the effect of improving stretchability cannot be obtained. In addition, when two or more types of specific thermoplastic resins are included in the A layer, the “content of the specific thermoplastic resin in the A layer” is the value of all the specific thermoplastic resins included in the A layer. It is the total content. In particular, the content of the polystyrene resin having a glass transition temperature of less than 40 ° C. is preferably within the above range.

  The A layer is not particularly limited, but may contain a resin other than the specific thermoplastic resin. Examples of the resin other than the specific thermoplastic resin include thermoplastic resins having a glass transition temperature of 40 ° C. or higher (for example, polyester resins, polyolefin resins, vinyl chloride resins, polycarbonate resins, polyamide resins, heat A plastic elastomer).

  The layer A may contain a recovered raw material (recycled material) as long as the effects of the present invention are not impaired. In this case, the content of the recovered raw material in the A layer is preferably 1 to 75% by weight with respect to the total weight (100% by weight) of the A layer from the viewpoint of recyclability.

  Among the above, the A layer is particularly preferably an A layer that satisfies at least one of the following (I) and (II). (I) a layer containing 90% by weight or more of the specific thermoplastic resin; (II) a polyester resin containing 25 to 90% by weight of the specific thermoplastic resin and having a glass transition temperature of 40 ° C. or higher and a glass transition temperature. A layer containing a total of 10 to 75% by weight of polystyrene resins at 40 ° C. or higher.

  The A layer satisfying the above (II) includes at least one of the specific thermoplastic resin, a polyester resin having a glass transition temperature of 40 ° C. or higher, and a polystyrene resin having a glass transition temperature of 40 ° C. or higher. Containing. The A layer satisfying the above (II) may contain one or both of a polyester resin having a glass transition temperature of 40 ° C. or higher and a polystyrene resin having a glass transition temperature of 40 ° C. or higher. It may be.

  The A layer satisfying the above (II) contains, in particular, 30 to 80% by weight of the specific thermoplastic resin, a polyester resin having a glass transition temperature of 40 ° C. or higher, and a polystyrene resin having a glass transition temperature of 40 ° C. or higher. A layer containing 20 to 70% by weight in total is preferable, containing 35 to 70% by weight of the specific thermoplastic resin, a polyester resin having a glass transition temperature of 40 ° C. or higher, and a polystyrene system having a glass transition temperature of 40 ° C. or higher. A layer containing a total of 30 to 65% by weight of the resin is more preferable. In the above (II), the glass transition temperature of the polyester resin and polystyrene resin is preferably 40 ° C. or higher, more preferably 45 ° C. or higher, and further preferably 50 ° C. or higher. Moreover, in said (II), the upper limit of the glass transition temperature of a polyester-type resin and a polystyrene-type resin has preferable 140 degreeC, More preferably, it is 120 degreeC, More preferably, it is 100 degreeC, Especially preferably, it is 90 degreeC.

(B layer)
The B layer is a layer containing 50% by weight or more of a polystyrene resin having a glass transition temperature of 40 ° C. or higher in the layer. In the present specification, the above “polystyrene resin having a glass transition temperature of 40 ° C. or higher” may be referred to as “specific polystyrene resin”.

  The glass transition temperature of the specific polystyrene resin is 40 ° C. or higher, preferably 45 ° C. or higher, more preferably 50 ° C. or higher. When the glass transition temperature of the specific polystyrene resin is 40 ° C. or higher, sufficient heat shrinkability can be obtained. When the glass transition temperature is less than 40 ° C., the orientation of the shrink film formed by stretching the unstretched film is poor, and the heat shrinkability is lowered. In addition, the suitability of shrink labels is reduced. In addition, the said glass transition temperature should just be in the range of the temperature at the time of carrying out heat shrink of a shrink label, and an upper limit is not specifically limited. The upper limit of the glass transition temperature is not particularly limited, but is preferably 140 ° C., more preferably 120 ° C., still more preferably 100 ° C., and particularly preferably from the viewpoint of being within the temperature range when the shrink label is actually thermally contracted. Is 90 ° C.

  Examples of the specific polystyrene-based resin include those having a glass transition temperature of 40 ° C. or higher among the polystyrene-based resins exemplified and described as the polystyrene-based resin that may be included in the surface layer. Of these, styrene-diene copolymers are preferred. As the specific polystyrene resin, only one type may be used, or two or more types may be used.

  Although it does not specifically limit as a styrene-type monomer of the monomer component which comprises the styrene-diene-type copolymer as said specific polystyrene-type resin, Styrene is preferable. Although it does not specifically limit as diene of the monomer component which comprises the said styrene diene type copolymer, A conjugated diene is preferable and 1, 3- butadiene is especially preferable.

  The form of copolymerization of the styrene-diene copolymer as the specific polystyrene resin is not particularly limited, but among these, block copolymers are preferable, styrene-butadiene block copolymers are more preferable, and styrene is more preferable. A styrene-butadiene block copolymer having blocks at both ends, particularly preferably SBS.

  The styrene-diene copolymer as the specific thermoplastic resin is not particularly limited, but the content of the structural unit derived from the styrene monomer is the total weight of the styrene-diene copolymer (100% by weight). ) Is preferably 50 to 95% by weight, more preferably 60 to 90% by weight, still more preferably 70 to 90% by weight, and particularly preferably 75 to 90% by weight. In addition, the styrene-diene copolymer as the specific thermoplastic resin is not particularly limited, but the content of the structural unit derived from diene is the total weight (100% by weight) of the styrene-diene copolymer. On the other hand, 5 to 50 weight% is preferable, More preferably, it is 10 to 40 weight%, More preferably, it is 10 to 30 weight%, Especially preferably, it is 10 to 25 weight%.

  The glass transition temperature of the styrene-diene copolymer as the specific polystyrene resin is, for example, the content of structural units derived from the styrene monomer in the styrene-diene copolymer or the structure derived from the diene. It can be adjusted according to the unit content, the molecular structure of the styrene-diene copolymer, the bonding state, and the like.

  Commercially available products may be used as the specific polystyrene resin. For example, “Clearen 530L”, “Clearen 730L” manufactured by Denki Kagaku Kogyo Co., Ltd., “Asaprene T411” manufactured by Asahi Kasei Co., Ltd., Kraton Polymer Japan Co., Ltd. "Clayton D1102A", "Clayton D1116A" manufactured by Stylorusion Corporation, "Styrolux S", "Styrolux T", manufactured by Asahi Kasei Chemicals Corporation, "Asaflex 840", "Asaflex 860" (and above, SBS) “679”, “HF77”, “SGP10” manufactured by PS Japan Co., Ltd., “Dick Styrene XC-515” manufactured by DIC Corporation, “Dick Styrene XC-535” (hereinafter GPPS), PS Japan Co., Ltd. “475D”, “H0103”, “HT478”, DIC ( "Dick styrene GH-8300-5" (above, HIPS) etc. are mentioned.

  The content of the polystyrene resin (specific polystyrene resin) having a glass transition temperature of 40 ° C. or higher in the B layer is 50% by weight or more, preferably 70% with respect to the total weight (100% by weight) of the B layer. % Or more, more preferably 80% by weight or more, and still more preferably 90% by weight or more. The upper limit of the content is not particularly limited, and may be 100% by weight. When the content is less than 50% by weight, the heat shrinkability is lowered. In addition, the suitability of shrink labels is reduced.

  The B layer is not particularly limited, but may contain a resin other than the specific polystyrene resin. Examples of the resin other than the specific polystyrene resin include polystyrene resins having a glass transition temperature of less than 40 ° C., polyester resins, polyolefin resins, vinyl chloride resins, polycarbonate resins, polyamide resins, and thermoplastic elastomers. And other thermoplastic resins. The content of the thermoplastic resin having a glass transition temperature of less than 40 ° C. in the B layer is not particularly limited, but is preferably less than 30% by weight, more preferably based on the total weight (100% by weight) of the B layer. Is 20% by weight or less, more preferably 10% by weight or less, and most preferably 0% by weight.

  B layer may contain the collection | recovery raw material (recycled material) in the range which does not impair the effect of this invention. In that case, the content of the recovered raw material in the B layer is preferably 50% by weight or less, more preferably 1 to 30% by weight, based on the total weight (100% by weight) of the B layer, from the viewpoint of recyclability. More preferably, it is 2 to 20% by weight.

(Outermost layer)
The outermost layer is a layer of the base layer portion and is a layer located on both end faces in the thickness direction. The outermost layer may be the A layer or the B layer, and may be a layer other than the A layer and the B layer, but is preferably the A layer.

(Middle layer)
The intermediate layer is a layer constituting the base layer portion, and is a layer other than the outermost layer. Although the said base layer part is not specifically limited, The layer for providing the various functions of a base layer part etc. can be used as said intermediate | middle layer, for example, intermediate layers other than A layer, B layer, A layer, and B layer Layer (other intermediate layer). The base layer portion preferably includes at least an A layer as the intermediate layer, and more preferably includes at least an A layer and a B layer. As said other intermediate | middle layer, layers other than A layer and B layer are mentioned among the layers illustrated and demonstrated as a layer in the above-mentioned base layer part.

  When there are a plurality of the other intermediate layers in the base layer portion, all or some of the plurality of other intermediate layers in the base layer portion may be the same layer, Different layers (layers having different resin compositions and layer thicknesses) may be used.

(Layer structure and physical properties of the base layer)
The number of layers included in the base layer portion is 5 to 65 layers, preferably 5 to 33 layers, and more preferably 9 to 33 layers. If the number of layers is less than 5, the effect of making the base layer multilayer is small, and the effect of improving the stretchability is small. On the other hand, when the number of layers exceeds 65 layers, the thickness of the A layer and the B layer (thickness per layer) becomes too thin when the thickness (total thickness) of the shrink film is in a range suitable for shrink labels. Thus, the effect of using the A layer and the B layer is reduced, the suitability for stretching is lowered, and the unstretched film is easily broken during stretching. In addition, by setting the number of layers in the base layer portion within the above range, the relatively soft A layer can be dispersed and provided in the base layer portion, and therefore the shrinkability of the shrink label is relatively excellent.

  The base layer portion includes, as the layer, one or more A layers, preferably two or more layers, and more preferably three or more layers. The upper limit of the number of layers of the A layer is not particularly limited, but may be 64 layers or less, preferably 33 layers or less, more preferably 17 layers or less.

  The base layer portion includes, as the layer, one or more B layers, preferably two or more layers, more preferably three or more layers. The upper limit of the number of layers of the B layer is not particularly limited, but may be 64 layers or less, preferably 33 layers or less, more preferably 17 layers or less.

  Although the total number of layers of A layer and B layer in the said base layer part is not specifically limited, 5-65 layer is preferable, More preferably, it is 5-33 layer, More preferably, it is 9-33 layer.

  The base layer portion preferably has a laminated structure in which the A layer and the B layer are adjacent (directly laminated). It is preferable that the base layer portion has the above-described laminated configuration because a decrease in cut suitability due to the A layer can be suppressed.

  The base layer portion is not particularly limited, but preferably has three or more interfaces formed by adjoining (directly laminating) the A layer and the B layer. The number of the interfaces is not particularly limited, but is preferably 3 or more, more preferably 4 or more, and still more preferably 5 or more. The upper limit of the number of interfaces is 64, preferably 32.

  In the base layer portion, the B layer is not particularly limited, but is preferably interposed between two or more A layers, and more preferably interposed between all the A layers in the base layer portion. In particular, in the base layer portion, the A layer and the B layer are not particularly limited, but are preferably alternately stacked, and more preferably directly stacked alternately without any other layer. That is, it is most preferable that the base layer portion includes 5 to 65 layers in total, alternately including A layers and B layers as layers in the base layer portion.

  The base layer portion may include 5 to 65 layers, and each layer in the base layer portion may include at least one layer A and one layer B. The laminated structure of the base layer part in the case where the base layer part is formed of only the A layer and the B layer is not particularly limited, but specifically, a laminated structure in which “A layer / B layer” is repeated as a repeating unit ( A layer / B layer / A layer / B layer /.../ A layer / B layer / A layer), (B layer / A layer / B layer / A layer /.../ B layer / A layer) / B layer), (A layer / B layer / A layer / B layer /.../ A layer / B layer) or (B layer / A layer / B layer / A layer /.../ B layer) / A layer). Further, the outermost layers on both surfaces of the base layer portion may be the A layer or the B layer, but the A layer is preferable.

  Although not particularly limited, when the base layer portion includes a plurality of A layers and a plurality of B layers, it is preferable that all A layers are formed from the same raw material, and that all the B layers are formed from the same raw material. It is preferable. That is, the A layers and the B layers are preferably formed from the same raw material. Particularly, all the A layers are preferably layers having the same composition, and all the B layers are preferably layers having the same composition.

(Configuration of shrink film of the present invention, physical properties, etc.)
The shrink film of the present invention includes the base layer portion and the surface layer. The surface layer is laminated on both sides of the base layer part, and is provided on one side and the other side of the base layer part, respectively.

  Although the thickness (total thickness) of the shrink film of this invention is not specifically limited, 10-100 micrometers is preferable, More preferably, it is 15-50 micrometers, More preferably, it is 20-45 micrometers. When the thickness is 10 μm or more, the rigidity is further improved and the waist becomes stronger, which is preferable.

  The thickness of the surface layer (thickness per layer) is not particularly limited, but is preferably 1 to 15 μm, more preferably 2 to 10 μm, still more preferably 2.5 to 8 μm, and particularly preferably 5 to 8 μm. When the thickness is 1 μm or more, the rigidity of the label is improved, which is preferable. When the thickness is 15 μm or less, delamination hardly occurs between the surface layer and the base layer portion, which is preferable. In addition, the thickness of each surface layer in the both surfaces side of the base layer part in the shrink film of this invention may be the same, and may mutually differ.

  Although the thickness of the said base layer part is not specifically limited, 5 micrometers or more are preferable, More preferably, it is 8-90 micrometers, More preferably, it is 10-45 micrometers, Most preferably, it is 11-40 micrometers. When the thickness is 5 μm or more, the rigidity of the label is improved, which is preferable. The thickness of 90 μm or less is preferable because delamination is difficult even when the delamination strength at the interface between layers in the base layer portion is relatively low.

  The thickness of each layer in the base layer portion (thickness per layer) is not particularly limited, but is preferably 0.2 μm or more (for example, 0.2 to 15 μm, preferably 0.2 to 10 μm), more preferably 0. .3 μm or more (for example, 0.3 to 5 μm). In addition, as for the thickness of the some layer in a base layer part, all or one part of them may be the same, and may mutually differ. For example, the layer that is in contact with the surface layer and that is the outermost layer of the base layer portion may be thinner than the layer in the base layer portion.

  Although the thickness (thickness per layer) of the said base layer part is not specifically limited, 0.2 micrometer or more (for example, 0.2-15 micrometers) is preferable, More preferably, it is 0.3-10 micrometers.

  The thickness of the intermediate layer (thickness per layer) is not particularly limited, but is preferably 0.3 μm or more (for example, 0.3 to 15 μm), more preferably 0.6 to 10 μm.

  The thickness of the A layer (thickness per layer) is not particularly limited, but is preferably 0.2 μm or more, more preferably 0.3 μm or more, and even more preferably 0.6 μm or more. It is preferable for the thickness to be 0.2 μm or more because the effect of having the A layer can be sufficiently obtained, and the drawing suitability can be further improved. Although the upper limit of the said thickness is not specifically limited, 15 micrometers is preferable, More preferably, it is 10 micrometers, More preferably, it is 5 micrometers. In addition, as for the thickness of several A layer in the shrink film of this invention, all or one part of them may be the same, and may mutually differ. For example, when the A layer is the outermost layer of the base layer portion, it may be thinner than the A layer that is an intermediate layer of the base layer portion.

  The thickness of B layer (thickness per layer) is not particularly limited, but is preferably 0.2 μm or more, more preferably 0.3 μm or more, and further preferably 0.6 μm or more. When the thickness is 0.2 μm or more, the effect of having the B layer can be sufficiently obtained, and sufficient heat shrinkability can be obtained. Although the upper limit of the said thickness is not specifically limited, 15 micrometers is preferable, More preferably, it is 10 micrometers, More preferably, it is 5 micrometers. In addition, as for the thickness of the some B layer in the shrink film of this invention, all or one part of them may be the same, and may mutually differ. For example, when the B layer is the outermost layer of the base layer portion, it may be thinner than the B layer that is an intermediate layer of the base layer portion.

  Ratio of thickness of A layer (total thickness of all A layers) and thickness of B layer (total thickness of all B layers) in the base layer portion [(thickness of A layer): (thickness of B layer) ] Is not particularly limited, but is preferably 2: 1 to 1:10, more preferably 1: 1 to 1: 8. If the B layer is thicker than 2: 1, the cut suitability is further improved, which is preferable. On the other hand, if the A layer is thicker than the above ratio of 1:10, the stretchability can be further improved, which is preferable.

  In the base layer portion, the thickness of the A layer (the total thickness of all the A layers) is the same as or thinner than the thickness of the B layer (the total thickness of all the A layers). Is preferably equal to or less than the thickness of the B layer (the total thickness of all the B layers).

  In the shrink film of the present invention, the ratio of the thickness of the surface layer (total thickness of all surface layers) and the thickness of the base layer [(thickness of the surface layer) :( thickness of the base layer)] is not particularly limited. 2: 1 to 1:10 are preferable, and 1: 1 to 1: 4 are more preferable. When the base layer is thicker than 2: 1, it is preferable because wrinkles and delamination between the surface layer and the base layer hardly occur. On the other hand, a thicker surface layer than the above ratio of 1:10 is preferable because the rigidity and wear resistance of the label are improved.

  The shrinkage stress at 90 ° C. of the shrink film of the present invention is not particularly limited, but is preferably 1 to 10N, more preferably 1 to 7N, still more preferably 1 to 5N, and particularly preferably 1 to 3N. It is preferable that the shrinkage stress is 1 N or more because the followability of the shrink label to the container and the like is improved. The shrinkage stress can be adjusted by, for example, the shrinkage film thickness, layer structure, raw material composition, surface layer, raw material composition or thickness constituting a layer (A layer, B layer, etc.) in the base layer. In the present specification, the shrinkage stress is measured with a measurement width of 15 mm.

  The shrinkage stress at 90 ° C. of the shrink film of the present invention is not particularly limited. For example, both ends of the shrink film are fixed and immersed in warm water at 90 ° C. so that there is no slack in the shrink film. Can be obtained by measuring the stress to be heat-shrinkable. The measuring machine used for the measurement of the shrinkage stress is not particularly limited, and examples thereof include “Shimadzu Autograph (AGS-50G: load cell type 500N)” manufactured by Shimadzu Corporation.

  The T-type peel strength between the surface layer and the base layer portion is not particularly limited, but preferably exceeds 0.8N, more preferably exceeds 0.9N, and further preferably exceeds 1N. The upper limit of the T-type peel strength is not particularly limited, but is preferably 10N or less, more preferably 8N or less. When the T-type peel strength exceeds 0.8 N, it is preferable because delamination between the surface layer and the base layer portion can be suppressed. The T-type peel strength can be measured by a T-type peel test at room temperature in accordance with, for example, JIS K 6854-3.

  The shrink film of the present invention is a film oriented in at least one direction (for example, a film oriented in one direction or a film oriented in one direction and a direction different from one direction) from the viewpoint of exhibiting shrink characteristics. preferable. Furthermore, it is preferable that all the film layers (each layer of the base layer portion including the surface layer, the A layer, and the B layer) are oriented in at least one direction. As the shrink film, in particular, a film oriented in one direction (uniaxially oriented film) or a film oriented in one direction and a direction orthogonal to one direction (biaxially oriented film) is often used. Films (including films that are stretched primarily in one direction and slightly stretched in a direction perpendicular to the one direction and substantially stretched in one direction) are generally used.

  The film oriented in at least one direction can be obtained by stretching an unstretched film in at least one direction. For example, when the film oriented in at least one direction is a uniaxially oriented film, it is obtained by stretching an unstretched film in one direction. When it is a biaxially oriented film, the unstretched film is oriented in one direction and the one direction. It is obtained by stretching in a direction orthogonal to the direction. In addition, the shrink label of this invention can be mainly heat-shrinked in the orientation direction of the shrink film of this invention.

  The shrinkage rate of the shrink film of the present invention (before shrink processing) in the main shrinkage direction at 90 ° C. for 10 seconds (warm water treatment) (sometimes referred to as “thermal shrinkage rate (90 ° C., 10 seconds)”) Although not particularly limited, it is preferably 30% or more, more preferably 40% or more, still more preferably 45% or more, still more preferably 50% or more, and particularly preferably 60% or more. When the thermal shrinkage rate (90 ° C., 10 seconds) is less than 30%, in the shrink processing step in which the shrink label is in close contact with the container by heat, the shrinkage is not sufficient, making it difficult to follow the shape of the container. The finish may be poor for shaped containers. The upper limit of the heat shrinkage rate (90 ° C., 10 seconds) is not particularly limited, but is preferably 90% and may be 85%. The “main shrinkage direction” is a direction having the largest thermal shrinkage rate, and is generally a direction mainly stretched, for example, a film stretched substantially in one direction in the width direction. In the case of the width direction.

  The shrink label of the present invention is particularly useful as a label having a high heat shrinkage rate. When the shrink label of the present invention has a high heat shrinkage ratio, the shrink film (before shrink processing) of the present invention in the main shrinkage direction at 100 ° C. for 10 seconds (warm water treatment) (“heat shrinkage ratio ( 100 ° C., 10 seconds) ”is preferably 60% or more, more preferably 80% or more. It is preferable that the heat shrinkage rate (100 ° C., 10 seconds) is 60% or more because the followability to the unevenness of the adherend is excellent when the shrink label is attached to the adherend.

  In addition, although the thermal contraction rate (90 degreeC, 10 second) of the direction orthogonal to the main contraction direction of the shrink film (before shrink process) of this invention is not specifically limited, -5-15% is preferable, More preferably -3 to 10%.

  When the shrink film of the present invention is transparent, the haze value [based on JIS K 7136, converted to a thickness of 40 μm, unit:%] of the shrink film is not particularly limited, but is preferably 10% or less. Preferably it is 7% or less, More preferably, it is 5% or less. When the haze value exceeds 10%, the inside of the shrink film (the side that becomes the container side when the shrink label is attached to the container) is printed, and the shrink label that shows the print through the shrink film (back printed shrink label) When used as a product, the printing may become cloudy and the decorativeness may deteriorate. However, even if the haze value exceeds 10%, it may be opaque in applications other than the above-described applications (print printed shrink labels) that show printing through a shrink film, and can be used sufficiently.

[Shrink label]
The shrink label of this invention is a shrink label which at least the shrink film of this invention has. The shrink label of the present invention may have a layer other than the shrink film of the present invention.

(Layers other than the shrink film of the present invention)
The layer other than the shrink film of the present invention contained in the shrink label of the present invention is not particularly limited, but other film layers such as a printing layer, a nonwoven fabric or a foamed sheet, an adhesive layer (pressure sensitive adhesive layer, heat sensitive layer). Adhesive layer, etc.), protective layer, anchor coat layer, primer coat layer, coating layer, antistatic layer, aluminum vapor deposition layer and the like.

(Print layer)
The print layer is not particularly limited, and examples thereof include known or commonly used print layers used in shrink labels. In addition, examples of the print layer include design print layers (color print layers and the like) such as product names, illustrations, handling precautions, and the like, background print layers formed in a single color such as white, films, and the like. Examples thereof include a protective printing layer provided for protecting the printing layer and a primer printing layer provided for improving the adhesion between the film and the printing layer. Although the said printing layer is not specifically limited, You may be provided only in the single side | surface side of the shrink film of this invention, and may be provided in the both surfaces side of the shrink film of this invention. Moreover, the said printing layer may be provided in the whole surface (surface on the side in which a printing layer is provided) of the shrink film of this invention, and may be provided in part. Furthermore, the printing layer is not particularly limited, but may be a single layer or a multilayer.

  Although the said printing layer is not specifically limited, It is preferable that binder resin is included as an essential component. Furthermore, it may contain additives such as color pigments such as blue, red, yellow, black, white, lubricants, dispersants, antifoaming agents, etc., as necessary. Each of the binder resins may be used alone or in combination of two or more.

  The binder resin is not particularly limited, and for example, a resin used as a binder resin in a known or commonly used printing layer or printing ink can be used. Examples of the binder resin include acrylic resins, urethane resins, polyester resins, polyamide resins, cellulose resins (including nitrocellulose resins), vinyl chloride-vinyl acetate copolymer resins, and the like. The color pigment is not particularly limited, and for example, a color pigment used in a known or conventional printing layer or printing ink can be used. For example, white pigments such as titanium oxide (titanium dioxide), indigo pigments 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 color 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, For example, 0.1-10 micrometers is preferable, More preferably, it is 0.3-5 micrometers. If the thickness is less than 0.1 μm, it may be difficult to provide a printing layer uniformly, and when partial “fading” occurs, decorativeness is impaired, or printing as designed becomes difficult There is. In addition, if the thickness exceeds 10 μm, a large amount of printing ink is consumed, which increases the cost, makes it difficult to apply uniformly, makes the printed layer brittle and easy to peel off, There is a case where the printing layer hardly follows the thermal shrinkage of the shrink film during the shrink processing.

  1 to 3 are schematic views (partial cross-sectional views) each showing an example of the shrink label of the present invention. The shrink label 3 of the present invention shown in FIG. 1 includes the shrink film 1 of the present invention and a printing layer 2 provided on one side of the shrink film 1 of the present invention. The shrink film 1 of the present invention includes a base layer portion 12 and a surface layer 11 provided on each side of the base layer portion 12. The base layer portion 12 is formed by laminating the outermost layers (layers in contact with the surface layer 11) of both layers as an A layer 12a and alternately laminating a total of nine A layers 12a and B layers 12b. In the base layer portion 12, the number of interfaces formed by adjoining (directly laminating) the A layer 12 a and the B layer 12 b is eight. Moreover, the surface layer 11 and the base layer part 12 are laminated | stacked directly, without passing through another layer. Specifically, the surface layer 11 and the A layer 12a that is the outermost layer of the base layer portion 12 are directly laminated without interposing other layers. Further, the B layer 12b is interposed between all the A layers 12a.

  The shrink label 3 of the present invention shown in FIG. 2 includes the shrink film 1 of the present invention and a printing layer 2 provided on one side of the shrink film 1 of the present invention. The shrink film 1 of the present invention includes a base layer portion 12 and a surface layer 11 provided on each side of the base layer portion 12. The shrink label 3 according to the present invention shown in FIG. 2 is a shrink label in which the base layer portion 12 is reverse in the positional relationship between the A layer 12a and the B layer 12b in relation to FIG. That is, the base layer portion 12 is formed by laminating both outermost layers (layers in contact with the surface layer 11) as a B layer 12b, and alternately laminating a total of nine A layers 12a and B layers 12b. In the base layer portion 12, the number of interfaces formed by adjoining (directly laminating) the A layer 12 a and the B layer 12 b is eight. Moreover, the surface layer 11 and the base layer part 12 are laminated | stacked directly, without passing through another layer. Specifically, the surface layer 11 and the B layer 12b which is the outermost layer of the base layer portion 12 are directly laminated without interposing other layers. Further, the B layer 12b is interposed between all the A layers 12a.

  The shrink label 3 of the present invention shown in FIG. 3 includes the shrink film 1 of the present invention and a printed layer 2 provided on one side thereof. The shrink film 1 of the present invention includes a surface layer 11 and a base layer portion 12. The base layer portion 12 is formed such that both outermost layers (layers in contact with the surface layer 11) are A layers 12a, and A layers 12a and B layers 12b are alternately laminated in total 17 layers. Yes. In the base layer portion 12, the number of interfaces formed by adjoining (directly laminating) the A layer 12a and the B layer 12b is 16. Also in FIG. 3, the surface layer 11 and the base layer portion 12 are directly laminated without interposing other layers, and the surface layer 11 and the A layer 12 a that is the outermost layer of the base layer portion 12 are interposing other layers. There is no direct lamination. Further, the B layer 12b is interposed between all the A layers 12a. In the shrink label 3 of the present invention shown in FIG. 3, the A layer 12a and the B layer 12b may be in the opposite positional relationship. Especially, the structure of the shrink label of FIG. 1 and the structure of the shrink label of FIG. 3 are preferable for the shrink label of this invention.

  Although the thickness (total thickness) of the shrink label of this invention is not specifically limited, 10-110 micrometers is preferable, More preferably, it is 15-60 micrometers, More preferably, it is 20-50 micrometers. When the thickness is 10 μm or more, the rigidity is increased and the label becomes stronger, which is preferable.

  The shrink label of the present invention is, for example, a cylindrical shrink label of a type in which both ends of the label are sealed with a solvent or an adhesive and attached to the container, and one end of the label is attached to the container, and the label is wound After that, it can be used as a wrapping type shrink label in which the other end is overlapped with one end to form a cylinder. Among the above, the shrink film of the present invention is particularly preferably used for a cylindrical shrink label. That is, the shrink label of the present invention is preferably a cylindrical shrink label. Hereinafter, the cylindrical shrink label using the shrink label of the present invention may be referred to as “the cylindrical shrink label of the present invention”.

  An example of a cylindrical shrink label which is a preferred embodiment of the shrink label of the present invention will be described with reference to FIGS. 4 and 5. The cylindrical shrink label 4 of the present invention shown in FIG. 4 is formed into a cylindrical shape by superimposing the other end on the outside of one end of the shrink label of the present invention formed in a rectangular shape. This is a cylindrical body in which a seal part 41 is formed by joining the outer surface of the part with a solvent or an adhesive. The cylindrical shrink label of the present invention includes the shrink film of the present invention, and the shrink film of the present invention is at least oriented in the circumferential direction D of the cylindrical shrink label of the present invention and can be thermally contracted in that direction. In addition, it is preferable that the cylindrical shrink label of this invention is mounted | worn so that the circumferential direction may turn into a main contraction direction.

  FIG. 5 is a cross-sectional view taken along the line AA ′ in FIG. 4, that is, an enlarged view of the main part in the vicinity of the seal part of the tubular shrink label 4 of the present invention. In the seal part 41, both ends of the shrink label are solvent or Bonded with an adhesive 53. Specifically, the shrink label 3 of the present invention is designed and printed in a region excluding the region of a predetermined width from the other end of one surface (surface on the cylindrical inner surface side) of the shrink film 1 of the present invention. The layer 52 is formed, and the background printing layer 51 is formed over substantially the entire region excluding the region of the predetermined width from the end of the other end of the one surface of the shrink film 1 so as to cover the design printing layer 52. Yes. For this reason, in the shrink label 3 of the present invention, the background print layer 51 and the design print layer 52 are not formed in the region having a predetermined width from the end of the other end, and the shrink film 1 of the present invention is exposed, A film exposed surface is formed, and the seal portion 41 includes a film exposed surface formed on the inner surface side of the other end portion of the shrink label 3 of the present invention and an outer surface (film exposed surface) of one end portion with a solvent or an adhesive. 53 are joined. That is, in the seal part 41, it is preferable that the shrink films 1 of the present invention are joined together with a solvent or an adhesive 53. In addition, even if it has a printing layer, such as a background printing layer and a design printing layer, the part which is not joined among the said both ends has an influence on adhesiveness, Therefore It may have a printing layer.

  In the cylindrical shrink label 4 of the present invention in FIG. 5, one end portion extends to a position where the end overlaps the background print layer 51 at the other end, and the background print layer 51 at the one end portion and the other end portion. A region where the layers overlap with each other via the shrink film 1 is formed. For this reason, there is no region where the background print layer 51 does not exist in the thickness direction. The cylindrical shrink label of the present invention may have a structure that overlaps the end of one end and the background printing layer on the other end as shown in FIG. 5, and the end of the one end is exposed to the film on the other end. It extends to the area that overlaps the surface, the end of one end does not extend to the position that overlaps the background print layer on the other end, and the end of the one end and the background print layer on the other end do not overlap Also good.

  Examples of the design printing layer include a layer displaying a trade name, an illustration, handling precautions, and the like. Although it does not specifically limit as said design printing layer, For example, the said printing layer etc. can be used. More specifically, the design print layer is formed by a plurality of print layers having different color pigments so as to have a desired design. Although the thickness of the said design printing layer is not specifically limited, 0.1-8 micrometers is preferable.

  The background print layer is a print layer serving as a background of the design print layer when the tubular shrink label of the present invention is observed from the outside of the tube. Although it does not specifically limit as said background printing layer, For example, the said printing layer etc. can be used. Especially, from a viewpoint used as the background of a design printing layer, background printing layers, such as a white printing layer containing 20-60 weight% of titanium oxide as a coloring pigment, are preferable. Although the thickness of the said background printing layer is not specifically limited, 0.5-10 micrometers is preferable.

  Although the width | variety of the said seal | sticker part is not specifically limited, 1-10 mm is preferable, More preferably, it is 2-4 mm.

  The shrink film in the shrink label of the present invention has a layer (A layer) containing 25% by weight or more of a thermoplastic resin having a glass transition temperature of less than 40 ° C. and 50% by weight or more of a polystyrene resin having a glass transition temperature of 40 ° C. or more. It has a base layer part having at least a layer (B layer) to be contained, and a surface layer provided on both sides of the base layer part. Accordingly, the base layer portion has at least a layer A having a relatively low glass transition temperature and mainly imparting stretchability to the film, and a layer B having a relatively high glass transition temperature and mainly imparting heat shrinkability of the film. The shrink film has heat shrinkability, and the composition in the shrink film is excellent in stretchability. Furthermore, since the base layer portion has a multi-layer structure by setting the base layer portion to 5 to 65 layers, the stretchability of the composition in the shrink film is further improved. For this reason, even if it is a case where an unstretched film is extended | stretched highly when producing a shrink film, it is hard to fracture | rupture and a shrink film with a higher heat shrinkage rate than before is obtained. Further, stretching unevenness can be suppressed, and a stable shrink film having physical properties can be obtained. Furthermore, when the base layer portion includes a plurality of A layers and B layers, the stretchability of the composition in the shrink film is further improved. In addition, since the A layer contains a resin having a relatively low glass transition temperature, shrink labels using the A layer tend to be relatively poor in cutting ability, but the base layer portion includes the B layer and has a multilayer structure. Therefore, since the position of the A layer can be dispersed in the base layer portion, it is possible to improve the cut suitability by suppressing the decrease in the cut suitability of the shrink film and the shrink label, rather than providing a thick A layer as a single layer. it can.

[Production method of shrink label of the present invention]
The manufacturing method of the shrink label of this invention includes the process of producing the shrink film of this invention at least. In the present specification, the “process for producing the shrink film of the present invention” may be referred to as a “film production process”. The manufacturing method of the shrink label of this invention may further include other processes (processes other than the said film preparation process), such as the process of forming layers other than the shrink film of this invention.

(Film production process)
In the film production step, the shrink film of the present invention can be produced by a conventional method such as melt film formation. Among these, the melt film forming method (particularly, the T-die method) is preferable. As a lamination method, a conventional method such as a co-extrusion method (feed block method, multi-manifold method, etc.), a dry lamination method, or the like can be used. Among these, the coextrusion method is preferable, and the feed block method is preferable. Further, it is preferable that the base layer is multilayered by using a layer multiplier, in particular, a combination of a feed block and a layer multiplier. The layer multiplier is a device that multi-layers film layers. The method of multilayering the film layer with the layer multiplier is not particularly limited, and examples thereof include a method of dividing the film layer in the width direction and then laminating the divided film layer in the thickness direction. In the present specification, the “layer multiplier” may be simply referred to as “multiplier”. The above multiplier can be obtained from, for example, EDI and Crawlen.

  A specific example of the coextrusion method (feed block method) will be described below. For example, the raw material for forming the base layer and the raw material for forming the surface layer are respectively charged into a plurality of extruders each set to a predetermined temperature, and co-extruded from a T-die. At this time, it is preferable to use a combination of a feed block and a multiplier to make the base layer portion multi-layered to have a predetermined laminated structure. Moreover, you may adjust supply_amount | feed_rate using a gear pump as needed. Furthermore, it is preferable to remove foreign substances using a filter because film tearing can be reduced. In addition, although extrusion temperature changes also with the kind of raw material to be used and is not specifically limited, 150-250 degreeC is preferable. A laminated unstretched film (sheet) can be obtained by quenching the coextruded polymer using a cooling drum or the like.

  Although the said film preparation process is not specifically limited, When a base layer part is formed from A layer and B layer, the raw material which may comprise A layer (it may be called "raw material (a)"), and B layer A first material that melts (or melt kneads) a constituent material (sometimes referred to as “raw material (b)”) and a raw material that constitutes the surface layer (sometimes referred to as “raw material (c)”). A second stage in which the raw material (a) and the raw material (b) melted (or melt-kneaded) in the first stage are laminated and further multilayered to form a laminated body; and the above It is preferable to include at least a third stage of laminating the raw material (c) melted in the first stage on both sides of the laminate formed in the second stage. Furthermore, other stages (stages other than the first stage, the second stage, and the third stage) may be included. The other stage is, for example, before the first stage, after the third stage, between the first stage and the second stage, between the second stage and the third stage, etc. It may be provided in the position.

  In the first stage, it is preferable to melt (or melt knead) the raw material (a), the raw material (b), and the raw material (c), respectively, using a known or conventional extruder. For example, the raw material (a), the raw material (b), and the raw material (c) can be charged into three extruders each set at a predetermined temperature, and melted (or melt-kneaded). Although extrusion temperature is not specifically limited, 150-250 degreeC is preferable.

  In the second stage, the laminate obtained by laminating the raw material (a) and the raw material (b) melted in the first stage and further multilayered is not particularly limited. The laminated body formed by sequentially laminating the raw material (a) and the raw material (b), or simultaneously laminating (coextrusion) using a feed block, is formed by further multilayering using a multiplier. The laminated body may be sufficient. The lamination is not particularly limited, but it is preferable to use a combination of a feed block and a multiplier. Each of the above feed blocks and multipliers may use only 1 or 2 or more. In the laminate, the total number of layers formed from the raw material (a) and the number of layers formed from the raw material (b) is preferably 5 to 65 layers, more preferably 5 to 33 layers, still more preferably. Is 9 to 33 layers. The laminate obtained in the second stage forms the base layer portion of the shrink film of the present invention.

  In the second stage, the laminated body obtained by laminating the raw material (a) and the raw material (b), and more specifically, the laminated body, specifically, for example, the raw material (a) melted in the first stage Then, the raw material (b) is extruded using a feed block to produce a laminate (sometimes referred to as “laminated body 1”) having a configuration of [raw material (a) / raw material (b) / raw material (a)]. Then, the laminate 1 is laminated as a unit using a multiplier, and [raw material (a) / raw material (b) / raw material (a) / raw material (a) / raw material (b) / raw material (a ) /... / Raw material (a) / Raw material (b) / Raw material (a)] can be obtained (may be referred to as “laminated body 2”).

  In addition, in the second stage, the laminated body obtained by laminating the raw material (a) and the raw material (b) and further multilayered is specifically the raw material melted in the first stage, for example. (A) and the raw material (b) are extruded using a feed block, and may be referred to as a laminated body having a configuration of [raw material (b) / raw material (a) / raw material (b)] (“laminated body 3”). Then, the laminate 3 as a unit is laminated using a multiplier, and [raw material (b) / raw material (a) / raw material (b) / raw material (b) / raw material (a) / It is also possible to obtain a laminated body (sometimes referred to as “laminated body 4”) having a structure of raw material (b) /... / Raw material (b) / raw material (a) / raw material (b)].

  In addition, in the second stage, the laminated body obtained by laminating the raw material (a) and the raw material (b) and further multilayered is specifically the raw material melted in the first stage, for example. (A) and the raw material (b) are extruded using a feed block to produce a laminate (sometimes referred to as “laminated body 5”) having a configuration of [raw material (a) / raw material (b)], Next, the laminate 5 as a unit is laminated using a multiplier, and [raw material (a) / raw material (b) / raw material (a) / raw material (b) /.../ raw material (a) / A laminate having the structure of the raw material (b)] (sometimes referred to as “laminate 6”) can be obtained. In addition, if the said laminated body 6 is followed from the reverse, [raw material (b) / raw material (a) / raw material (b) / raw material (a) /.../ raw material (b) / raw material (a)]. It is also a laminate having a structure.

  In the third stage, the raw material (c) melted in the first stage is applied to both sides of the laminate (for example, the laminate 2, 4, or 6) formed in the second stage. When laminating, it is preferable to use a feed block. The laminated raw material (c) forms the surface layer of the shrink film of the present invention. By the third step, a multilayer structure in which the raw material (c) melted in the first step is laminated on both sides of the laminate formed in the second step is obtained.

  Although not particularly limited, a laminated unstretched film is obtained by co-extruding the laminated body formed through the first stage, the second stage, and the third stage from a T die and rapidly cooling it using a cooling drum or the like. (Sheet) can be obtained.

  [Raw material (a) / Raw material (b) / Raw material (a) / Raw material (a) / Raw material (b) / Raw material (a) /.../ Raw material (a) / Raw material (b) / Raw material ( a)] has a structure of [A layer / B layer / A layer / A layer / B layer / A layer /... / A layer / B layer / A layer]. Although it should be the base layer portion, in practice, the interface of [A layer / A layer] formed from [raw material (a) / raw material (a)] obtained by laminating the same material of the laminate 2 becomes invisible. Since it becomes one A layer, it becomes a base layer portion having a structure of [A layer / B layer / A layer / B layer /... / A layer / B layer / A layer]. Similarly, the portion of [B layer / B layer] formed from [raw material (b) / raw material (b)] obtained by laminating the same material of the above-described laminate 4 becomes one B layer because the interface becomes invisible. The base layer should have a structure of [B layer / A layer / B layer / B layer / A layer / B layer /... / B layer / A layer / B layer]. Layer / A layer / B layer / A layer /... / B layer / A layer / B layer]. In addition, in the said base layer part, when the laminated body [A1 layer / A2 layer] formed by laminating | stacking the raw material which forms two different A layers (A1 layer and A2 layer) exists, [A1 layer / A2 layer] ] Cannot be seen as one A layer because the interface is visible. The same applies to the case where there is a laminate [B1 layer / B2 layer] formed by laminating raw materials for forming two different B layers (B1 layer and B2 layer). In addition, when the surface layer and the outermost layer (resin layer) of the base layer portion are layers made of the same resin composition, the interface is not visible, and there is one surface layer and the outermost layer of the base layer portion. Layer (surface layer).

  The laminated unstretched film produced in the third stage further has a stage of stretching. The stage of stretching (stretching stage) includes biaxial stretching, longitudinal direction or width in the longitudinal direction (film production line direction, also referred to as MD direction) and the width direction (direction orthogonal to the longitudinal direction, also referred to as TD direction). Uniaxial stretching in the direction can be used. As the stretching method, any of a roll method, a tenter method, and a tube method may be used. In the case of biaxial stretching, biaxial stretching may be performed simultaneously, or biaxial stretching may be sequentially performed. More specifically, for example, after stretching at a stretching temperature of 65 to 100 ° C. and a stretching ratio of 1.05 to 1.50 in the longitudinal direction by a roll method, stretching at a stretching temperature of 70 to 100 ° C. in the width direction by a tenter method. The film is stretched at a magnification of 3 to 8 times (preferably 4 to 7 times).

  Although it does not specifically limit as said other step, The step of performing a surface treatment etc. are mentioned.

  Examples of the step of performing the surface treatment include a step of performing conventional surface treatments such as corona discharge treatment, primer treatment, and flame treatment on the surface of the shrink film of the present invention.

  In the film preparation process, the example in which the base layer part is formed only from the A layer and the B layer has been described. However, when the layer other than the A layer and the B layer is included, the base layer part and the laminated unstretched film are formed by the same process. Can be produced. Moreover, although the said film preparation process showed the example which melt | dissolves and uses three types of raw materials, it is not limited to this, Two types of raw materials (for example, raw material (a) and raw material (b)) are used. A first stage of melting, and a second stage of stacking two kinds of raw materials (for example, the raw material (a) and the raw material (b)) that are melted in the first stage to form a laminate. In this case, the third stage is not provided, and the outermost layer of the second-stage laminate is the surface layer.

(Other processes)
Although it does not specifically limit in the manufacturing method of the shrink label of this invention, You may have the process of providing a printing layer, the process of providing a protective layer, etc. as processes (other processes) other than a film preparation process.

  In the step of providing the printing layer, the printing layer is formed by performing one or more printing steps in which printing ink is applied and solidified by drying or the like on at least one surface of the shrink film of the present invention. For example, one or more printing steps can be performed to form a design printing layer, and then one or more printing steps can be performed to form a background printing layer. For the step of providing the above-mentioned printing layer, a well-known and commonly used printing method can be used, and among them, a gravure printing method or a flexographic printing method is preferable.

  The printing ink is produced, for example, by mixing the binder resin, the color pigment, a solvent, and other additives as necessary. Mixing can be carried out by a known or conventional mixing method, and is not particularly limited. For example, a mixer such as a paint shaker, butterfly mixer, planetary mixer, pony mixer, dissolver, tank mixer, homomixer, homodisper, A mill such as a roll mill, a sand mill, a ball mill, a bead mill, or a line mill, or a mixing device such as a kneader is used. The mixing time (retention time) during mixing is not particularly limited, but is preferably 10 to 120 minutes. The obtained printing ink may be used after being filtered, if necessary. Each of the above components (binder resin, color pigment, solvent, and other additives) may be used alone or in combination of two or more.

  As said solvent (solvent), the organic solvent etc. which are normally used for printing ink can be used. Examples of the solvent include esters such as acetates (ethyl acetate, propyl acetate, butyl acetate, etc.); alcohols such as methanol, ethanol, isopropyl alcohol, propanol, and butanol; ketones such as methyl ethyl ketone and methyl isobutyl ketone; toluene, xylene Aromatic hydrocarbons such as hexane, octane, etc .; Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; Glycols such as ethylene glycol and propylene glycol; Ethylene glycol monopropyl ether, Propylene glycol monomethyl ether, Propylene Glycol ethers such as glycol monobutyl ether; Glycol ether esters such as propylene glycol monomethyl ether acetate It is. The solvent can be removed by drying after applying the printing ink to the shrink film of the present invention. The solvent (solvent) also includes the meaning of “dispersion medium”.

(Manufacturing method of cylindrical shrink label)
Although the manufacturing method of the cylindrical shrink label of this invention is not specifically limited, For example, it is as follows. A long length of the shrink film of the present invention is optionally provided with a printing layer and the like, then slit to a predetermined width, and a plurality of shrink labels of the present invention are continuous in the long direction (longitudinal direction). Get the body. This long label is formed in a cylindrical shape by overlapping so that the main shrinkage direction (that is, the main shrinkage direction of the shrink film of the present invention) is the circumferential direction, and the other end is outside the one end. Then, the overlapped portion is sealed in a band shape with a predetermined width, and both end portions are joined together to obtain a long cylindrical label continuous body (long cylindrical shrink label). By cutting this long cylindrical shrink label in the width direction so that the longitudinal direction has a predetermined length, one cylindrical shrink label having a predetermined length in the height direction (the cylindrical shrink label of the present invention) ) Can be obtained.

  Various cutters such as a guillotine cutter and a rotary cutter can be used for cutting the long cylindrical shrink label. Examples of the apparatus used for cutting the long cylindrical shrink label include a guillotine cutter having a fixed blade and a movable blade that can move forward and backward with respect to the fixed blade, and a rotary cutter as shown in FIGS. Etc. The long cylindrical shrink label is generally cut before being attached to a container or the like in a labeler (label attaching machine).

  The rotary cutter 61 shown in FIG. 6 (the figure seen from the width direction one side of the elongate cylindrical shrink label 6) is provided with the fixed blade 62 and the rotary blade 63 which is a movable blade. The rotary cutter 61 is disposed on the upstream side of the labeler, for example. The long cylindrical shrink label 6 is supplied to the labeler in a state of being folded into a flat shape and wound up in a roll shape, and is passed between the fixed blade 62 and the rotary blade 63 by a feed roller 64 or the like. In the rotary cutter 61, the rotary blade 63 rotates so as to feed the long cylindrical shrink label 6 downstream, and the length between the two blades when the blade edge of the rotary blade 63 comes close to the fixed blade 62. It is cut so that the tubular shrink label 6 is pushed out.

  A rotary cutter 71 shown in FIG. 7 (viewed from one side in the longitudinal direction of the long cylindrical shrink label 6) includes a disk-shaped rotary blade 72 that revolves on a path 74 while rotating about a shaft 73. . Similarly to the example shown in FIG. 6, the long cylindrical shrink label 6 is supplied to the labeler in a state of being folded flat, and is drawn out so as to pass through the vicinity of the path 74 where the rotary blade 72 revolves. The rotating blade 72 that rotates rotates moves the long cylindrical shrink label 6 across the width direction (circumferential direction D), and cuts the long cylindrical shrink label.

  The cylindrical shrink label is manufactured by cutting the long tubular shrink label as described above. However, depending on the shrink label, so-called cut fusion occurs in which the inner surfaces of the labels are joined at the time of the cut. There is a case. In particular, when the guillotine cutter or the rotary cutter 6 shown in FIG. 6 is used, cut fusion is likely to occur at the opening on the upstream side of the cylindrical shrink label due to, for example, the influence of frictional heat or pressing during cutting. However, since the shrink label of the present invention has relatively good cut suitability, cut fusion is unlikely to occur. Even if cut fusion occurs, the degree of fusion is small and can be easily separated. For this reason, the shrink label of the present invention can be used not only for a labeler equipped with a cutter that is difficult to cut and fuse, but also for a labeler equipped with a cutter that is relatively easy to cut and fuse, and has excellent versatility.

  In addition, when providing the perforation for label cutting to a cylindrical shrink label, the perforation of predetermined length and pitch is formed in the vertical direction (direction orthogonal to the circumferential direction). The perforation can be applied by a conventional method (for example, a method of pressing a disk-shaped blade having a cut portion and a non-cut portion repeatedly formed around it, a method using a laser, or the like). The step of perforating can be selected as appropriate after the step of providing the printed layer or before or after the step of processing into a cylindrical shape.

[Container with label]
Although the shrink label of this invention is not specifically limited, It mounts | wears with a container and is used as a labeled container. In addition, the shrink label of this invention may be used for adherends other than a container. For example, the shrink label of the present invention (particularly, the cylindrical shrink label) is placed around the container so that the shrink label of the present invention is in a cylindrical shape, and attached to the container by heat shrinking. A container (a labeled container having the shrink label of the present invention) is obtained. Examples of the containers include soft drink bottles such as PET bottles, milk bottles for home delivery, food containers such as seasonings, bottles for alcoholic beverages, pharmaceutical containers, containers for chemical products such as detergents and sprays, and toiletries. Containers, cup noodle containers and the like are included. Although it does not specifically limit as a shape of the said container, For example, various shapes, such as bottle types, such as cylindrical shape and a square shape, and a cup type, are mentioned. The material of the container is not particularly limited, and examples thereof include plastic such as PET, glass, and metal.

  The labeled container can be produced, for example, by externally fitting a cylindrical shrink label to a predetermined container, and then thermally shrinking the cylindrical shrink label by heat treatment so as to follow and closely adhere to the container (shrink processing). Examples of the heat treatment method include a method of passing through a hot air tunnel or a steam tunnel, a method of heating with radiant heat such as infrared rays, and the like. In particular, a method of treating with steam at 80 to 100 ° C. (passing through a heating tunnel filled with steam and steam) is preferable. Moreover, 101-140 degreeC dry steam can also be used. Although the said heat processing is not specifically limited, It is preferable to implement in the temperature range from which the temperature of a shrink film will be 85-100 degreeC (especially 90-97 degreeC). Since the shrink film of the present invention can be heat-treated at a particularly high temperature, it can be used for containers that require high shrinkage. Moreover, the processing time of heat processing has preferable 4 to 20 second from a viewpoint of productivity and economical efficiency.

  EXAMPLES Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

  In Table 1, the raw material for the surface layer (raw material (c)), the raw material for the A layer (raw material (a)), the raw material for the B layer (raw material (b)), and the A layer used in Examples and Comparative Examples The composition of the raw material (A ′ layer raw material) for forming the resin layer (A ′ layer) used in place of the above, the structure and evaluation results of the shrink film and the shrink label produced in Examples and Comparative Examples are shown.

Example 1
(material)
As a raw material constituting the A layer (raw material for the A layer), 100% by weight of polystyrene resin C (“Tuftec H1221” manufactured by Asahi Kasei Chemicals Corporation, Tg: less than 0 ° C.) was used.
As a raw material constituting the B layer (B layer raw material), 20% by weight of polystyrene resin A (manufactured by Stylorusion, trade name “Styrolux S”, Tg: 65 to 75 ° C.), polystyrene resin B (stylo 80% by weight of a product name “Styrolux T” (Tg: 45 to 55 ° C.) manufactured by Roussion Co.
As a raw material constituting the surface layer (surface layer raw material), 100% by weight of polyester-based resin A (manufactured by Eastman Chemical, trade name “EMBRACE 21214”, Tg: 71 ° C.) was used.

(Shrink film)
The raw material for the A layer was charged into the extruder x heated to 220 ° C, the raw material for the B layer was charged into the extruder y heated to 220 ° C, and the raw material for the surface layer was charged into the extruder z heated to 220 ° C. Melt extrusion was performed using the above three extruders. Using a laminating apparatus that combines a molten A-layer raw material and a molten B-layer raw material with a two-layer / three-layer feed block and a four-part multiplier, the A-layer raw material / B-layer Dividing, merging and laminating 2 types and 3 layers of raw material / A layer raw material as one repeating unit, laminated body (I) (4 types of the above described 2 types and 3 layers are laminated (4 repetitions)) The melted raw material for the surface layer was merged and laminated on both sides of the laminate (I) using a feed block to obtain a laminate (II). Furthermore, after extruding the laminate (II) from a T-die, the laminate (II) was rapidly cooled on a casting drum cooled to 25 ° C. to obtain a laminated unstretched film in which surface layers were respectively provided on both sides of the base layer portion. .
Next, the laminated unstretched film is stretched six times at 85 ° C. in the width direction to be stretched mainly in the width direction, and a stretched film (shrink film) having heat shrinkability in the direction. Got.

(Cylinder shrink label)
A design printing layer and a white background printing layer were formed on the long body of the shrink film obtained above by a gravure printing machine to obtain a long body of a shrink label. Next, after slitting the long body of the shrink label so as to have a predetermined width, one end and the other end are overlapped to form a cylinder so that the width direction is the circumferential direction. The shrink film surfaces of the part were sealed with a solvent to obtain a cylindrical long body of a shrink label. Furthermore, the cylindrical long body (label continuous body) of the shrink label was cut into individual label sizes to obtain a cylindrical shrink label.

Example 2
As shown in Table 1, a shrink film and a cylindrical shrink label were obtained in the same manner as in Example 1 by changing the composition and component ratio of the raw material (a), the raw material (b), and the raw material (c).

  In Example 1 and Example 2, the shrink film is [surface layer / A layer / B layer / A layer / B layer / A layer / B layer / A layer / B layer / A layer / surface layer]. 11 layers. In the above-mentioned shrink film, the base layer portion is 12 layers because the repeating unit of 2 types, 3 layers configuration is laminated with the repetition number 4, but the portion where the raw materials for the A layer overlap is actually the interface between the layers. It disappears and overlaps into a single layer. For this reason, the base layer portion has a nine-layer configuration of [A layer / B layer / A layer / B layer / A layer / B layer / A layer / B layer / A layer], and the outermost layer of the base layer portion is It is A layer. In the base layer portion, the number of interfaces where the A layer and the B layer are formed adjacent to each other is eight.

Comparative Example 1
(material)
As a raw material constituting the A layer (A layer raw material), 100% by weight of polystyrene resin C was used.
As the raw material constituting the B layer (B layer raw material), 20% by weight of polystyrene resin A and 80% by weight of polystyrene resin B were used.
100% by weight of polyester-based resin A was used as a raw material (surface layer raw material) constituting the surface layer.

(Shrink film)
The raw material for the A layer was charged into the extruder x heated to 220 ° C, the raw material for the B layer was charged into the extruder y heated to 220 ° C, and the raw material for the surface layer was charged into the extruder z heated to 220 ° C. Melt extrusion was performed using the above three extruders. 2 types 3 layers composition of A layer raw material / B layer raw material / A layer raw material using a feed block of a 2 type 3 layer confluence system for molten A layer raw material and molten B layer raw material The laminated body (III) was prepared, and the melted raw material for the surface layer was joined and laminated on both sides of the laminated body (III) using a feed block to obtain a laminated body (IV). Furthermore, after extruding the laminate (IV) from a T-die, it was rapidly cooled on a casting drum cooled to 25 ° C. to obtain a laminated unstretched film in which surface layers were provided on both sides of the base layer portion, respectively. .
Next, the laminated unstretched film is stretched six times at 85 ° C. in the width direction to be stretched mainly in the width direction, and a stretched film (shrink film) having heat shrinkability in the direction. Got.

  The shrink film has a five-layer configuration of [surface layer / A layer / B layer / A layer / surface layer]. Therefore, in the shrink film, the base layer portion has a three-layer configuration of [A layer / B layer / A layer], and the outermost layer of the base layer portion is the A layer. In the base layer portion, the number of interfaces formed by adjoining the A layer and the B layer is 2.

(Cylinder shrink label)
Using the shrink film obtained above, a cylindrical shrink label was obtained in the same manner as in Example 1.

Comparative Example 2
Instead of using the raw material for the A layer, 80% by weight of the polystyrene resin A and 20% by weight of the polystyrene resin B were used as the raw material for the A ′ layer, and the laminated unstretched film was used in the width direction. A shrink film and a cylindrical shrink label were produced in the same manner as in Example 1 except that the tenter was stretched 4 times at 85 ° C.

  In Comparative Example 2, the base layer part in the shrink film is 12 layers because the repeating unit of 2 types, 3 layers structure is laminated with a repetition number of 4, but in fact, the part where the raw materials for the A ′ layer overlap each other Makes the interface between the layers invisible and overlaps to form one layer. For this reason, the shrink film has 11 layers of [surface layer / A ′ layer / B layer / A ′ layer / B layer / A ′ layer / B layer / A ′ layer / B layer / A ′ layer / surface layer]. It has a configuration. Therefore, in the shrink film, the base layer portion has a 9-layer structure of [A ′ layer / B layer / A ′ layer / B layer / A ′ layer / B layer / A ′ layer / B layer / A ′ layer]. The outermost layer of the base layer is the A ′ layer.

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

(1) Stretchability (breaking strength)
The presence or absence of breakage when the film (unstretched film) before stretching of the shrink film obtained in Examples and Comparative Examples was stretched 6 times at 85 ° C. in the width direction was confirmed. The stretchability was evaluated according to the following criteria.
Stretchability is good (○): No breakage Stretchability is poor (x): Breakage

(2) Cut suitability The shrink films obtained in the examples and comparative examples were formed into a cylindrical shape, and the degree of pressure bonding of the cut surface when cut in the width direction with a rotary type cutting machine shown in FIG. 6 was confirmed. The cut suitability was evaluated according to the following criteria.
Good cutting suitability (○): Strong crimping feeling when cutting Poor cutting suitability (×): Weak feeling when cutting

  As can be seen from Table 1, the shrink film of the shrink label of the present invention (Examples 1 and 2) has excellent stretchability of the composition, and when the unstretched film is stretched 6 times to form a shrink film. It did not break. Moreover, the cut suitability was also good. On the other hand, the shrink label (Comparative Example 1) having three layers in the base layer portion was inferior in cut suitability although the stretchability of the composition in the shrink film was excellent. A shrink label (Comparative Example 2) in which the base layer portion does not have a layer (A layer) containing 25% by weight or more of a thermoplastic resin having a glass transition temperature of less than 40 ° C. has a stretchability of the composition in the shrink film. It was low and broke when attempting to form a shrink film by stretching the unstretched film 6 times. The thermal shrinkage rate of the cylindrical shrink label produced in Example 2 was 65% at 100 ° C.

DESCRIPTION OF SYMBOLS 1 Shrink film of this invention 11 Surface layer 12 Base layer part 12a A layer 12b B layer 2 Print layer 3 Shrink label of this invention 4 Cylindrical shrink label 41 Seal part D Circumferential direction 51 Background printing layer 52 Design printing layer 53 Solvent or adhesive

Claims (5)

A shrink label having a shrink film,
The shrink film has a base layer portion and surface layers provided on both sides of the base layer portion,
The base layer portion includes 5 to 65 layers, and the layer in the base layer portion includes a layer (A layer) containing 25% by weight or more of a thermoplastic resin having a glass transition temperature of less than 40 ° C., and a glass transition temperature. A shrink label comprising at least a layer (B layer) containing 70 % by weight or more of a polystyrene resin at 40 ° C. or higher.   The shrink label according to claim 1, wherein the thermoplastic resin having a glass transition temperature of less than 40C is a polystyrene resin having a glass transition temperature of less than 40C.   The A layer contains 25 to 90% by weight of a thermoplastic resin having a glass transition temperature of less than 40 ° C, a polyester resin having a glass transition temperature of 40 ° C or higher, and a polystyrene resin having a glass transition temperature of 40 ° C or higher. The shrink label according to claim 1 or 2, which is a layer containing 10 to 75% by weight in total.   The thickness of the A layer (thickness per layer) is 0.2 to 15 μm, the thickness of the B layer (thickness per layer) is 0.2 to 15 μm, and the thickness of the A layer (for all the A layers) The shrink label according to any one of claims 1 to 3, wherein the total thickness) is equal to or less than the thickness of the B layer (the total thickness of all the B layers).   The shrink label according to any one of claims 1 to 4, wherein the base layer portion includes a total of 5 to 65 layers of A layers and B layers alternately as layers in the base layer portion.

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