WO2012132632A1

WO2012132632A1 - Shrink film and shrink label

Info

Publication number: WO2012132632A1
Application number: PCT/JP2012/054049
Authority: WO
Inventors: 那央上陰; 英明梅田; 篤志新庄
Original assignee: 株式会社フジシールインターナショナル
Priority date: 2011-03-30
Filing date: 2012-02-21
Publication date: 2012-10-04
Also published as: JPWO2012132632A1

Abstract

The purpose of the present invention is to provide a shrink film which is a hybrid laminate film comprising a resin layer composed of a polypropylene resin and a resin layer composed of an aromatic polyester resin, and which rarely undergoes the interlayer delamination during a shrink processing. This shrink film is characterized by having a laminated structure that is produced by laminating a resin layer (a layer (A)), a resin layer (a layer (B)) and a resin layer (a layer (C)) in the order of "(layer (A))/(layer (B))/(layer (C)" without providing any other layer between them, wherein the layer (A) comprises an aromatic polyester resin, the layer (B) comprises 60-78 wt% of a constituent unit derived from ethylene, 18-24 wt% of a constituent unit derived from methyl methacrylate and 1-3.5 wt% of a constituent unit derived from 1-butene, and the layer (C) comprises a polypropylene resin.

Description

Shrink film and shrink label

The present invention relates to a shrink film. More specifically, the present invention relates to a heterogeneous laminated shrink film having a resin layer composed of a polypropylene resin and a resin layer composed of an aromatic polyester resin, and is less prone to delamination even during heat shrinkage.

Currently, plastic bottles such as PET bottles and metal bottles such as bottle cans are widely used as beverage containers for 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 film, there is known a heterogeneous laminated film in which different resin materials are laminated for the purpose of imparting various functions to the film. For example, a laminated structure comprising a resin layer composed mainly of an aromatic polyester resin, an intermediate layer composed mainly of an ethylene-vinyl acetate resin, and a resin layer composed mainly of a polypropylene resin. The shrink film which has is known (refer patent document 1). Since the shrink film has a resin layer made of a polypropylene resin, the specific gravity is small and light, and when used as a shrink label, it can be easily separated from a PET bottle or the like by utilizing the difference in specific gravity at the time of recovery. In addition, by having a resin layer made of an aromatic polyester-based resin, it is excellent in shrinkage characteristics and strength characteristics (waist strength), and when the layer is used as a surface layer, it is excellent in printability. . In addition, since the interlayer strength (interlayer adhesion) is improved by the intermediate layer, delamination hardly occurs even during shrink (heat shrink) processing.

However, shrinking processing conditions tend to be more severe, such as when high shrinkage is required or when shrinkage is required under high temperature conditions due to workability at the installation factory. For example, the processing temperature tends to be higher and the heating conditions tend to be abrupt (the temperature rising rate is increased). When processed under such severer shrink processing conditions, even the shrink film described in the above-mentioned patent document is likely to cause delamination particularly in the center seal portion, and the delamination deterrent effect is It was not enough. For this reason, even if it is a case where it processes by severe shrink processing conditions, the present condition is that the shrink film which does not produce delamination easily is calculated | required.

International Publication No. 2009/084212 Pamphlet

That is, an object of the present invention is a dissimilar laminated film having a resin layer composed of a polypropylene resin and a resin layer composed of an aromatic polyester resin, and a shrink film that hardly causes delamination even during shrink processing. Is to provide.

As a result of intensive studies to achieve the above object, the present inventors have found that a resin layer (A layer) containing an aromatic polyester resin, a resin layer (B layer) containing a specific amount of a specific structural unit, and a polypropylene resin. By having at least a three-layered / three-layered structure of A layer / B layer / C layer consisting of a resin layer (C layer), excellent delamination hardly occurs even when severe shrink processing is performed. The present inventors have found that a shrink film having delamination deterrence can be obtained and completed the present invention.

That is, the present invention relates to a resin layer (A layer) containing an aromatic polyester resin, 60 to 78% by weight of structural units derived from ethylene, 18 to 24% by weight of structural units derived from methyl methacrylate, 1- A resin layer (B layer) containing 1 to 3.5% by weight of a structural unit derived from butene and a resin layer (C layer) containing a polypropylene-based resin are added in the order of A layer / B layer / C layer. There is provided a shrink film having a laminated structure in which layers are not interposed.

Further, in the present invention, the B layer is at least one selected from the group consisting of an ethylene-methyl methacrylate copolymer, an ethylene-1-butene copolymer, and an ethylene-1-butene-methyl methacrylate copolymer. The shrink film is a resin layer containing an ethylene copolymer.

Furthermore, the present invention provides the shrink film having a laminated structure in which the layers are laminated in the order of A layer / B layer / C layer / B layer / A layer without any other layers.

Also, the present invention provides a shrink label including the shrink film.

Since the shrink film of the present invention has the above-described configuration, it is a heterogeneous laminated film having a resin layer composed of a polypropylene resin and a resin layer composed of an aromatic polyester resin. Even when shrink processing is performed under severe conditions such as heating, delamination hardly occurs. For this reason, since shrinkage | contraction at high temperature is attained, mounting | wearing with respect to the container which requires higher shrinkage is attained. Therefore, it is useful as a base film for shrink labels attached to containers such as PET bottles.

The shrink film of the present invention comprises a resin layer containing an aromatic polyester resin (hereinafter sometimes referred to as “A layer”), a constitutional unit derived from methyl methacrylate in an amount of 60 to 78% by weight derived from ethylene. A resin layer containing 18 to 24% by weight of units and 1 to 3.5% by weight of a structural unit derived from 1-butene (hereinafter sometimes referred to as “B layer”), and a resin layer containing a polypropylene resin ( Hereinafter, it may be referred to as “C layer”).

The shrink film of the present invention is laminated in the film without any other layers in the laminated structure in which the A layer and the C layer are laminated via the B layer, that is, in the order of A layer / B layer / C layer. And at least a three-layered / three-layered structure. Furthermore, the shrink film of the present invention has a laminated structure (3 types and 5 layers laminated structure) laminated in the order of A layer / B layer / C layer / B layer / A layer without any other layers. It is preferable. In the laminated structure of the above-mentioned A layer / B layer / C layer / B layer / A layer, the A layers provided on the both sides of the C layer and the B layers have the same resin composition. The layer is preferably a layer having a different resin composition as long as the effects of the present invention are not impaired. In addition, the A layers and the B layers provided one by one on both sides of the C layer may be layers having the same thickness or different thicknesses.

Although it does not specifically limit as a shrink film of this invention, For example, 3 types 3 layer laminated film of A layer / B layer / C layer, A layer (surface layer) / B layer (intermediate layer) / C layer (center) Layer) / B layer (intermediate layer) / A layer (surface layer), and a five-layer laminated film. The shrink film of this invention may have layers other than A layer, B layer, and C layer further. Layers other than the A layer, the B layer, and the C layer are not particularly limited, but a layer that can be provided in-line in the film forming process of the laminated film is preferable. For example, an anchor coat layer, an easy adhesion layer, an antistatic layer Examples thereof include a coating layer such as an agent layer.

[A layer]
The A layer is a resin layer containing at least an aromatic polyester resin. The aromatic polyester resin is a polyester resin containing an aromatic ring in the molecule. Examples of the aromatic polyester-based resin include various polyesters 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). And polyesters containing at least a dicarboxylic acid containing an aromatic dicarboxylic acid and a polymer obtained by a condensation reaction of a diol, a copolymer, or a mixture thereof. The above aromatic polyester resins can be used alone or in combination of two or more.

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 ludicarboxylic acid, 2,5-anthracene dicarboxylic acid, 2,5-pyridinedicarboxylic acid and their substitutes; 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-decahydronaphtha Njikarubon acid, and 2,6-decahydronaphthalene dicarboxylic acid and alicyclic dicarboxylic acids such as substituted versions thereof and the like. These dicarboxylic acids can be used alone or in combination of two or more.

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 Alicyclic diols such as 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol; 2,2-bis (4-β- Examples thereof include ethylene oxide adducts of bisphenol compounds such as hydroxyethoxyphenyl) propane and bis (4-β-hydroxyethoxyphenyl) sulfone, and aromatic diols such as xylylene glycol. These diols can be used alone or in combination of two or more.

In addition to the above, the aromatic 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 acids such as trimellitic acid. It may contain a structural unit derived from a carboxylic acid; a monohydric alcohol such as polyalkylene glycol monomethyl ether; a polyhydric alcohol such as glycerin, pentaerythritol, or trimethylolpropane.

In the aromatic polyester-based resin, 50 mol% or more (particularly 70 mol% or more) in the total dicarboxylic acid component is 50 mol% or more (particularly 70 mol%) in the aromatic dicarboxylic acid component and / or the total diol component. % Or more) is preferably an aromatic diol component. Among these, from the viewpoint of shrinkage characteristics, the content of the aromatic dicarboxylic acid component in the total dicarboxylic acid component is preferably 80 mol% or more (80 to 100 mol%), more preferably 90 mol% or more (90 to 100 mol). %).

The aromatic polyester-based resin is made of a single repeating unit from the viewpoint of improving delamination deterrence and improving the shrinkage rate (thermal shrinkage rate) of the entire shrink film by becoming amorphous. Instead, a modified aromatic polyester-based resin containing a modifying component (copolymerization component) is preferable. 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. Is 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 the modifying component (copolymerization component) of the modified aromatic polyester resin (particularly modified PET) include cyclohexanedicarboxylic acid, adipic acid, and isophthalic acid. 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.

Specifically, as the aromatic polyester-based resin, in terms of shrinkage properties, polyethylene terephthalate (PET) using terephthalic acid as a dicarboxylic acid component and ethylene glycol (EG) as a diol component; Modified aromatic polyester-based resin using terephthalic acid, ethylene glycol as the diol component, and 1,4-cyclohexanedimethanol (CHDM) as the copolymer component (sometimes referred to as “CHDM copolymerized PET”) A modified aromatic polyester resin using terephthalic acid as the dicarboxylic acid component, ethylene glycol as the diol component, and 2,2-dialkyl-1,3-propanediol as the copolymer component (“2,2- Dialkyl-1,3-propanedioe Sometimes referred to as copolymerized PET ") are preferred. Among the above 2,2-dialkyl-1,3-propanediol copolymerized PET, in particular, terephthalic acid is used as the dicarboxylic acid component, ethylene glycol is the main component as the diol component, and neopentyl glycol (NPG) is the copolymerized component. The modified aromatic polyester-based resin used as (sometimes referred to as “NPG copolymerized PET”) is particularly preferable. Further, diethylene glycol may be 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 preferably 15 mol% or more (for example, 15 to 40 mol%) from the viewpoint of optimizing the thermal deformation behavior of the A layer and reducing delamination. Among them, for example, in the case of CHDM copolymerized PET, the proportion of CHDM is preferably 20 to 40 mol% (EG is 60 to 80 mol%) in all diol components (that is, relative to 100 mol% of terephthalic acid), More preferably, it is 25 to 35 mol% (EG is 65 to 75 mol%). 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, 15 to 40 mol% (EG is 60 to 85 mol%) is preferable. Furthermore, a part of the EG component (preferably 1 to 10 mol% in the total diol component) may be replaced with diethylene glycol.

The aromatic polyester resin is preferably a substantially amorphous aromatic polyester resin, and 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 is possible, and the flow behavior of the A layer can be brought close to the flow behavior of the B layer and the C layer. Thereby, the layer formability of the A layer at the time of extrusion processing is improved, and the delamination at the time of shrink processing is less likely to occur by improving the adhesion with the B layer.

The crystallinity of the aromatic polyester resin measured by the 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 aromatic polyester-based resin is most preferably a resin that hardly shows a 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., performing a nitrogen seal at a sample amount of 10 mg and a heating rate of 10 ° C./min. The temperature can be determined from the area of the melting peak when the temperature is lowered 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 aromatic polyester resin is subtracted from the melting peak of the resin to be mixed. You can ask for.

The weight average molecular weight (Mw) of the aromatic polyester resin is preferably 15000 to 90000, more preferably 30000 to 80000, from the viewpoint of melting behavior and shrinkage behavior. In the case of 2,2-dialkyl-1,3-propanediol copolymerized PET, 50000-70000 is more preferable.

The glass transition temperature (Tg) of the aromatic polyester resin is preferably 60 to 80 ° C., more preferably 60 to 75 ° C. The Tg can be controlled by the type of dicarboxylic acid or diol constituting the aromatic polyester resin and the copolymerization ratio of the copolymerization component (modification component) used for modification. When the Tg of the aromatic polyester resin is in the above range, the thermal deformation behavior (change in shrinkage stress with respect to temperature) is close to that of the polypropylene resin constituting the C layer. The difference in shrinkage stress generated between them becomes small, and delamination during shrink processing hardly occurs. When Tg exceeds 80 ° C., during shrink processing, the A layer shrinks rapidly at a high temperature, and the shrinkage stress difference increases with the C layer that gradually shrinks from a relatively low temperature, resulting in delamination. It may be easier.

The glass transition temperature (Tg) 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 IV value (intrinsic viscosity) of the aromatic polyester resin is preferably 0.70 (dl / g) or more from the viewpoint of interlayer strength, more preferably 0.70 to 0.90 (dl / g), It is preferably 0.75 to 0.85 (dl / g).

Commercially available products may be used as the aromatic polyester-based resin. For example, “EMBRACE 21214”, “EMBRACE LV” (above, CHDM copolymerized PET) manufactured by Eastman Chemical (Eastman Chemical), Bell Co., Ltd. “Belpet MGG200” manufactured by Polyester Products, “Belpet E02” manufactured by Bell Polyester Products Co., Ltd. (NPG copolymerized PET, etc.), etc. are available on the market.

The content of the aromatic polyester resin in the A layer is not particularly limited, but the total weight of the A layer (100) from the viewpoint of shrinkage characteristics (heat shrinkage rate), heat resistance, strength, chemical resistance, printability, and the like. % By weight) is preferably 50% by weight or more (50 to 100% by weight), more preferably 80 to 100% by weight, still more preferably 90 to 100% by weight.

The layer A may contain components other than the aromatic polyester-based resin (additive components), for example, lubricants, fillers, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, if necessary. A coloring agent, a pinning agent (alkaline earth metal) and the like may be included.

[B layer]
The B layer is a resin containing 60 to 78% by weight of structural units derived from ethylene, 18 to 24% by weight of structural units derived from methyl methacrylate, and 1 to 3.5% by weight of structural units derived from 1-butene. Is a layer. The layer B comprises at least one ethylene copolymer selected from the group consisting of an ethylene-methyl methacrylate copolymer (EMMA), an ethylene-1-butene copolymer, and an ethylene-1-butene-methyl methacrylate copolymer. A resin layer containing a coalescence is preferable. Further, the layer B is preferably a resin layer containing at least an ethylene-methyl methacrylate copolymer and an ethylene-1-butene copolymer or a resin layer containing at least an ethylene-1-butene-methyl methacrylate copolymer. More preferably, the resin layer contains at least an ethylene-methyl methacrylate copolymer and an ethylene-1-butene copolymer. The ethylene-methyl methacrylate copolymer, ethylene-1-butene copolymer, and ethylene-1-butene-methyl methacrylate copolymer may be used singly or in combination of two or more. Also good.

The ethylene-methyl methacrylate copolymer (EMMA) is a copolymer composed of ethylene and methyl methacrylate (methyl methacrylate) as essential monomer components (monomer components). (B) a copolymer containing at least a structural unit derived from ethylene and a structural unit derived from methyl methacrylate. In addition, as a monomer component which comprises the said EMMA, if it exists in the range which does not prevent the effect of this invention, you may use copolymerization components other than the said ethylene and methylmethacrylate. Examples of the copolymer component other than ethylene and methyl methacrylate include propylene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and the like. Α-olefins (preferably α-olefins having 3 to 20 carbon atoms); vinyl monomers such as vinyl chloride; (meth) acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, 5- Unsaturated carboxylic acids such as norbornene-2,3-dicarboxylic acid; unsaturated carboxylic anhydrides such as maleic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, tetrahydrophthalic anhydride; acrylic acid Methyl, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, (meth) a Unsaturated carboxylic esters such as 2-ethylhexyl crylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, monoethyl maleate, diethyl maleate; acrylamide, Examples thereof include unsaturated amides or imides such as methacrylamide and maleimide; unsaturated carboxylates such as sodium (meth) acrylate and zinc (meth) acrylate. These copolymerization components can be used alone or in combination of two or more.

The content of the structural unit derived from ethylene in the ethylene-methyl methacrylate copolymer is not particularly limited, but from the viewpoint of controlling the behavior of the B layer at the time of melting, the total weight of the ethylene-methyl methacrylate copolymer ( 100 to 80% by weight), preferably 50 to 80% by weight, more preferably 60 to 78% by weight.

The content of the structural unit derived from methyl methacrylate in the ethylene-methyl methacrylate copolymer is not particularly limited, but the adhesiveness (adhesiveness) with the A layer and the C layer, and the flexibility during stretching or shrinking From the viewpoint of imparting properties, it is preferably 20 to 50% by weight, more preferably 20 to 40% by weight, still more preferably 22 to 30% by weight based on the total weight (100% by weight) of the ethylene-methyl methacrylate copolymer. %.

The weight average molecular weight of the ethylene-methyl methacrylate copolymer is preferably 100,000 to 200,000, more preferably 130,000 to 150,000, from the viewpoint of behavior during melting and flexibility.

The melt flow rate (MFR) (temperature 190 ° C., load 2.16 kgf) of the ethylene-methyl methacrylate copolymer is preferably 1 to 10 (g / 10 min) from the viewpoint of behavior at the time of melting and flexibility, More preferably, it is 6 to 8 (g / 10 minutes). In this specification, MFR can be measured based on JIS K7210.

Commercially available products may be used as the ethylene-methyl methacrylate copolymer, and for example, “ACRlift WK307” manufactured by Sumitomo Chemical Co., Ltd. is commercially available.

The ethylene-1-butene copolymer is a copolymer comprising ethylene and 1-butene as essential monomer components, that is, a structural unit derived from ethylene in a molecule (in one molecule) and It is a copolymer containing at least a structural unit derived from 1-butene. As the monomer component constituting the ethylene-1-butene copolymer, a copolymer component other than the ethylene and 1-butene may be used as long as the effects of the present invention are not impaired. . Examples of copolymer components other than ethylene and 1-butene include propylene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene and 1-decene. Α-olefins (preferably α-olefins having 3 to 20 carbon atoms); vinyl monomers such as vinyl chloride; (meth) acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, 5 -Unsaturated carboxylic acids such as norbornene-2,3-dicarboxylic acid; unsaturated carboxylic anhydrides such as maleic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, tetrahydrophthalic anhydride; acrylic Methyl methacrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid 2 -Unsaturated carboxylic esters such as ethylhexyl, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, monoethyl maleate, diethyl maleate; acrylamide, methacrylamide, Examples thereof include unsaturated amides or imides such as maleimide; unsaturated carboxylates such as sodium (meth) acrylate and zinc (meth) acrylate. These copolymerization components can be used alone or in combination of two or more.

The content of the structural unit derived from 1-butene in the ethylene-1-butene copolymer is not particularly limited, but from the viewpoint of improving the heat resistance of the B layer, the total amount of the ethylene-1-butene copolymer is not limited. The amount is preferably 2 to 20% by weight, more preferably 10 to 15% by weight based on the weight (100% by weight).

The content of the structural unit derived from ethylene in the ethylene-1-butene copolymer is not particularly limited, but from the viewpoint of controlling the behavior of the B layer during melting, the total amount of the ethylene-1-butene copolymer is not limited. It is preferably 80 to 98% by weight, more preferably 85 to 90% by weight, based on the weight (100% by weight).

The weight average molecular weight of the ethylene-1-butene copolymer is preferably from 100,000 to 200,000, more preferably from 130,000 to 150,000, from the viewpoint of behavior during melting and flexibility.

The melt flow rate (MFR) (temperature 190 ° C., load 2.16 kgf) of the ethylene-1-butene copolymer is preferably 1 to 15 (g / 10 minutes) from the viewpoint of behavior at the time of melting and flexibility. More preferably, it is 1 to 10 (g / 10 minutes), and further preferably 6 to 8 (g / 10 minutes).

Commercially available products may be used as the ethylene-1-butene copolymer, and for example, “Excellen VL700” manufactured by Sumitomo Chemical Co., Ltd. is commercially available.

The ethylene-1-butene-methyl methacrylate copolymer is a copolymer composed of ethylene, 1-butene and methyl methacrylate as essential monomer components, that is, ethylene in the molecule (in one molecule). A copolymer containing at least a structural unit derived from 1-butene, a structural unit derived from methyl methacrylate. The monomer component constituting the ethylene-1-butene-methyl methacrylate copolymer is a copolymer other than ethylene, 1-butene and methyl methacrylate as long as it does not interfere with the effects of the present invention. Ingredients may be used. Examples of copolymer components other than ethylene, 1-butene, and methyl methacrylate include propylene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, Α-olefins such as 1-decene (preferably α-olefins having 3 to 20 carbon atoms); vinyl monomers such as vinyl chloride; (meth) acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citracone Acids, unsaturated carboxylic acids such as 5-norbornene-2,3-dicarboxylic acid; unsaturated carboxylic anhydrides such as maleic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, tetrahydrophthalic anhydride, etc. Acid; methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate , Unsaturated carboxylic acids such as 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, monoethyl maleate, diethyl maleate Examples include esters; unsaturated amides or imides such as acrylamide, methacrylamide, and maleimide; and unsaturated carboxylates such as sodium (meth) acrylate and zinc (meth) acrylate. These copolymerization components can be used alone or in combination of two or more.

The content of the structural unit derived from ethylene in the ethylene-1-butene-methyl methacrylate copolymer is not particularly limited, but from the viewpoint of controlling the behavior of the B layer during melting, ethylene-1-butene-methyl The amount is preferably 60 to 78% by weight, more preferably 70 to 78% by weight, based on the total weight (100% by weight) of the methacrylate copolymer.

The content of the structural unit derived from 1-butene in the ethylene-1-butene-methyl methacrylate copolymer is not particularly limited, but from the viewpoint of improving the heat resistance of the B layer, ethylene-1-butene-methyl It is preferably 1 to 3.5% by weight, more preferably 1.2 to 3% by weight, based on the total weight (100% by weight) of the methacrylate copolymer.

The content of the structural unit derived from methyl methacrylate in the ethylene-1-butene-methyl methacrylate copolymer is not particularly limited, but the adhesiveness with the A layer and the C layer, and the flexibility during stretching and shrinking From the viewpoint of imparting properties, it is preferably 18 to 24% by weight, more preferably 20 to 23% by weight, based on the total weight (100% by weight) of the ethylene-1-butene-methyl methacrylate copolymer.

The content of structural units derived from ethylene in the B layer is 60 to 78% by weight, preferably 70 to 78% by weight, based on the total weight (100% by weight) of the B layer. If the content is less than 60% by weight, it is difficult to form a layer, and if it exceeds 78% by weight, the layer is easily peeled off at room temperature and when heated (when contracted or stretched).

The content of structural units derived from methyl methacrylate in the B layer is 18 to 24% by weight, preferably 20 to 23% by weight, based on the total weight (100% by weight) of the B layer. When the content is less than 18% by weight, the adhesiveness of the B layer is insufficient, delamination is likely to occur at room temperature, and the flexibility during heating is insufficient, so that whitening or peeling during stretching or contraction is not possible. It becomes easy to get up. On the other hand, when the content exceeds 24% by weight, the layer form cannot be maintained during heating, and peeling tends to occur.

The content of the structural unit derived from 1-butene in the B layer is 1 to 3.5% by weight, preferably 1.2 to 3% by weight, based on the total weight (100% by weight) of the B layer. %. When the content is less than 1% by weight, the heat resistance of the B layer is lowered, and particularly when shrink processing is performed at a high temperature, delamination easily occurs during shrink processing. Flexibility is insufficient, and whitening during stretching and peeling during shrinkage tend to occur.

The contents of the structural unit derived from ethylene, the structural unit derived from methyl methacrylate, and the structural unit derived from 1-butene in the B layer can be controlled mainly by the composition of the resin constituting the B layer. For example, when the layer B is a resin layer containing an ethylene-methyl methacrylate copolymer and an ethylene-1-butene copolymer, the content of structural units derived from ethylene in the ethylene-methyl methacrylate copolymer and methyl Content of structural unit derived from methacrylate, content of structural unit derived from ethylene in ethylene-1-butene copolymer, content of structural unit derived from 1-butene, and ethylene in the B layer It can be controlled mainly by the content of the methyl methacrylate copolymer and the content of the ethylene-1-butene copolymer.

More specifically, for example, in the B layer, ethylene-methyl whose content of structural units derived from ethylene is e ₁ (% by weight) and whose content of structural units derived from methyl methacrylate is m (% by weight). A methacrylate copolymer, an ethylene-1-butene copolymer in which the content of structural units derived from ethylene is e ₂ (wt%) and the content of structural units derived from 1-butene is b (wt%) And the content of the ethylene-methyl methacrylate copolymer in the B layer is W ₁ (% by weight), and the content of the ethylene-1-butene copolymer in the B layer is W ₂ (% by weight). ), The contents of the structural unit derived from ethylene, the structural unit derived from methyl methacrylate, and the structural unit derived from 1-butene in the B layer can be generally controlled as follows. Content of structural unit derived from ethylene in layer B (% by weight) = (e ₁ × W ₁ + e ₂ × W ₂ ) / 100 Content of structural unit derived from methyl methacrylate in layer B (% by weight) = (M × W ₁ ) / 100 Content of constituent unit derived from 1-butene in layer B (% by weight) = (b × W ₂ ) / 100

Analysis / measurement of the structural unit in the B layer (structural unit derived from ethylene, structural unit derived from methyl methacrylate and structural unit derived from 1-butene) and the content of the structural unit is not particularly limited. , Nuclear magnetic resonance (NMR), gas chromatograph mass spectrometer (GCMS) and the like. In addition, analysis / measurement of other resin layers (A layer, C layer, etc.) and constituent units in the resin and the content of the constituent units can be performed in the same manner.

When the B layer is a resin layer containing at least an ethylene-methyl methacrylate copolymer and an ethylene-1-butene copolymer, the content of the ethylene-methyl methacrylate copolymer in the B layer is It is preferably 45 to 95% by weight, more preferably 60 to 92% by weight, based on the total weight (100% by weight). Further, the content of the ethylene-1-butene copolymer in the B layer is preferably 5 to 55% by weight, more preferably 8 to 40% by weight with respect to the total weight (100% by weight) of the B layer. is there.

When the B layer is a resin layer containing at least an ethylene-1-butene-methyl methacrylate copolymer, the content of the ethylene-1-butene-methyl methacrylate copolymer in the B layer is determined by the total amount of the B layer. It is preferably 90 to 100% by weight, more preferably 99 to 100% by weight, based on the weight (100% by weight).

The resin constituting the B layer is not limited to ethylene-methyl methacrylate copolymer, ethylene-1-butene copolymer, and ethylene-1-butene-methyl methacrylate copolymer. For example, the B layer may be formed using polyethylene, polymethyl methacrylate, and poly-1-butene.

If necessary, the layer B may contain components other than the ethylene copolymer (additive components), such as lubricants, fillers, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, A polymer plasticizer (petroleum resin, etc.), a coloring agent, a pinning agent (alkaline earth metal) and the like may be contained.

Temperature dependence of the loss tangent (tan δ) determined by dynamic viscoelasticity measurement of the B layer (resin composition constituting the B layer) (temperature-tan δ curve. Hereinafter, referred to as “dynamic viscoelastic curve”) Tan δ is preferably less than 1 to 1 or more in the temperature range of 80 to 97 ° C. (80 ° C. or more and 97 ° C. or less). Hereinafter, the temperature at which tan δ is less than 1 to 1 or more in the measurement temperature range from room temperature (30 ° C.) to 120 ° C. is referred to as “T (tan δ ≧ 1)”. T (tan δ ≧ 1) is preferably higher than 85 ° C. and lower than or equal to 96 ° C., more preferably higher than 90 ° C. and lower than or equal to 95 ° C. The T (tan δ ≧ 1) is an index of the temperature at which the B layer softens to such an extent that it can sufficiently follow the shrinkage. The shrink film and the shrink label of the present invention are not particularly limited, but it is desirable that the shrink processing is performed at a temperature at which the film temperature is about 80 to 100 ° C. When shrink processing is performed at a temperature lower than 80 ° C., it may be difficult to shrink a portion that requires high shrinkage. On the other hand, when shrink processing is performed at a temperature exceeding 100 ° C., deformation of a plastic container or This is because the contents may be deteriorated. When T (tan δ ≧ 1) is in the above range, the B layer has moderate fluidity at the shrinking processing temperature such that the film temperature is about 80 to 97 ° C. Good followability to the shrinkage of the layer and effective adhesion (adhesiveness, interlayer adhesion). When T (tan δ ≧ 1) exceeds 97 ° C., the B layer still does not have sufficient fluidity at the shrinkage processing temperature, so the followability to the deformation of the A layer and the C layer is poor, and delamination tends to occur. There is a case. On the other hand, when T (tan δ ≧ 1) is less than 80 ° C., the fluidity of the B layer becomes too high at the shrinkage processing temperature, and the form of the layer may not be maintained. T (tan δ ≧ 1) can be easily controlled within the above range by controlling the content of the structural unit derived from methyl methacrylate and the structural unit derived from 1-butene in the B layer. In addition, said "resin composition which comprises B layer" is "resin which comprises B layer", when B layer is comprised only from single resin.

The above T (tan δ ≧ 1) is obtained by dynamic viscoelasticity measurement. Specifically, the temperature dependence (dynamic viscoelastic curve) of tan δ is obtained by dynamic viscoelasticity measurement, and the temperature at which tan δ is less than 1 to 1 or more (tan δ = 1) in the dynamic viscoelastic curve. Is defined as T (tan δ ≧ 1). The dynamic viscoelasticity measurement is performed under the conditions of frequency: 1 Hz, rate of temperature increase: 2 ° C./min, measurement temperature: room temperature (30 ° C.) to 120 ° C. The evaluation apparatus is, for example, Seiko Instruments Inc. “EXSTAR6000 DMS6100” manufactured by the company can be used.

The weight average molecular weight of the B layer (resin composition constituting the B layer) is preferably 100,000 to 200,000, more preferably 130,000 to 150,000, from the viewpoint of the flexibility of the layer. In addition, said "resin composition which comprises B layer" is "resin which comprises B layer", when B layer is comprised only from single resin.

[C layer]
The C layer is a resin layer containing at least a polypropylene resin. The polypropylene resin is a polymer composed of propylene as an essential monomer component, that is, a polymer containing at least a structural unit derived from propylene in a molecule (in one molecule). The polypropylene resin may be, for example, a propylene homopolymer or a copolymer (propylene-α-olefin copolymer) containing a copolymer component such as α-olefin. The polypropylene resin is particularly preferably a polypropylene resin obtained by polymerization with a metallocene catalyst (metallocene catalyst polypropylene, metallocene catalyst propylene-α-olefin copolymer, etc.), propylene-α-olefin random copolymer. It is a coalescence. These polypropylene resins can be used alone or in combination of two or more.

The propylene content in the polypropylene resin (that is, the content of structural units derived from propylene in the polypropylene resin) is the total weight of the polypropylene resin (100 from the viewpoint of shrinkage, strength, and specific gravity of the shrink film). % By weight) is preferably 50 to 100% by weight, more preferably 60 to 100% by weight.

The propylene-α-olefin copolymer is a copolymer composed of propylene and α-olefin as essential monomer components, that is, a structural unit derived from propylene in a molecule (in one molecule) and A copolymer containing at least a structural unit derived from an α-olefin. The α-olefin used as a copolymerization component of the propylene-α-olefin copolymer is ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1- Examples thereof include α-olefins having about 4 to 20 carbon atoms such as octene, 1-nonene and 1-decene. These α-olefins can be used alone or in admixture of two or more. Among these, an ethylene-propylene random copolymer containing ethylene as a copolymerization component is particularly preferable. In the ethylene-propylene random copolymer, the ratio of ethylene to propylene is, for example, the former / the latter (weight ratio) = 2/98 to 5/95 (preferably 3/97 to 4.5 / 95.5). You can choose from a range of

Furthermore, as the propylene-α-olefin copolymer (particularly, ethylene-propylene random copolymer), from the viewpoint of improving the low temperature shrinkage at about 60 to 80 ° C. and the fit to the container during heat shrinkage, A copolymer obtained by copolymerization using a metallocene catalyst is preferred. Further, from the viewpoint of low-temperature shrinkage and the strength of the shrink film, those having an isotactic index of 90% or more are preferable.

As the metallocene catalyst, a known or conventional metallocene catalyst for olefin polymerization can be used. The polymerization method (copolymerization method) is not particularly limited, and a known polymerization method such as a slurry method, a solution polymerization method, or a gas phase method can be employed.

Commercially available products may be used as the polypropylene resin, “Wintech WFX6” (metallocene catalyst-based propylene-ethylene random copolymer) manufactured by Nippon Polypro Co., Ltd., “Zeras # 7000, #” manufactured by Mitsubishi Chemical Corporation. 5000 ”,“ Kernel ”manufactured by Nippon Polyethylene Co., Ltd. are available on the market.

The weight-average molecular weight of the polypropylene resin is preferably 100,000 to 500,000, more preferably 200,000 to 400,000 from the viewpoint of controlling the melting behavior of the resin forming the C layer within a preferable range.

The melting point of the polypropylene resin is preferably 100 to 150 ° C., more preferably 120 to 140 ° C. The melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) is preferably 0.1 to 10 g / 10 minutes, more preferably 1 to 5 g / 10 minutes, from the viewpoint of controlling the melting behavior. If the melting point or MFR is out of the above range, the difference in melting characteristics and thermal characteristics between the resin forming the A layer and the resin forming the C layer becomes large, and sheeting or stretching by coextrusion during shrink film production. May become difficult, and may cause a decrease in productivity such as film breakage and a decrease in shrinkage due to insufficient orientation.

The content of the polypropylene-based resin in the C layer is preferably 40% by weight or more (40 to 100% by weight), more preferably 50 to 94% by weight, further based on the total weight (100% by weight) of the C layer. Preferably, it is 55 to 89% by weight. When the content of the polyolefin resin in the C layer is less than 40% by weight, the shrink film may not have a low specific gravity or the shrinkage characteristics may be deteriorated.

The C layer may contain a polyethylene resin for the purpose of preventing film breakage and improving shrink workability. The polyethylene-based resin is a polymer composed of ethylene as an essential monomer component, that is, a polymer containing at least a structural unit derived from ethylene in a molecule (in one molecule). The polyethylene-based resin is not particularly limited, and publicly known or commonly used polyethylene can be used. For example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene, medium density Examples include polyethylene and high density polyethylene (HDPE). Among these, low density polyethylene (including linear low density polyethylene and ultra-low density polyethylene) having a density of less than 0.930 (g / cm ³ ) is preferable, and linear low density polyethylene is particularly preferable. Furthermore, linear low density polyethylene (metallocene catalyst system LLDPE) polymerized using a metallocene catalyst is most preferred. Commercially available products may be used as the polyethylene resin. For example, LLDPE “2040FC” manufactured by Ube Maruzen Polyethylene Co., Ltd., “Kernel KF380”, “Kernel KF260T”, “Kernel KS340T” manufactured by Nippon Polyethylene Co., Ltd. "Evolue SP2040" manufactured by Prime Polymer Co., Ltd. is available on the market.

The content of the polyethylene resin in the C layer is preferably 1 to 10% by weight, more preferably 1 to 5% by weight with respect to the total weight (100% by weight) of the C layer.

The C layer may contain a polymer plasticizer from the viewpoint of improving the shrinkability of the shrink film. 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. The above polymeric plasticizers can be used alone or in combination of two or more. 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.

When the polymer plasticizer is added, the content of the polymer plasticizer (particularly petroleum resin) in the C layer is preferably 5 to 30% by weight with respect to the total weight (100% by weight) of the C layer. More preferably, it is 10 to 25% by weight. If the content exceeds 30% by weight, the shrink film may become brittle. On the other hand, if it is less than 5% by weight, the effect of adding the polymer plasticizer may be small.

The C layer may contain other components (additive components) as necessary, for example, lubricants, fillers, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, colorants, pinning agents. (Alkaline earth metal) and the like may be contained.

The C layer may contain a recovered raw material as long as the effects of the present invention are not impaired. In this case, the content of the recovered material in the C layer is preferably 1 to 75% by weight, more preferably 1% with respect to the total weight (100% by weight) of the C layer from the viewpoint of recyclability and shrinkage. % Or more and less than 50% by weight. 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 materials are limited to those produced from the manufacture of the shrink film of the present invention (so-called self-collected products).

[Shrink film]
As described above, the shrink film of the present invention has a laminated structure in which an A layer, a B layer, and a C layer are laminated in the order of A layer / B layer / C layer without any other layer (3 types, 3 layers). At least). Although the shrink film of this invention is not specifically limited, 3 types 3 layer lamination shrink films of A layer / B layer / C layer and 3 types 5 layer lamination of A layer / B layer / C layer / B layer / A layer A shrink film is preferred. In addition, the above-mentioned “laminated in the order of A layer / B layer / C layer without other layers” means more specifically the order of A layer / B layer / C layer and A layer The B layer is laminated without sandwiching other layers such as an adhesive layer between both layers, and the B layer and the C layer are laminated without sandwiching other layers such as an adhesive layer between both layers. Indicates that

The above laminated structures (for example, A layer / B layer / C layer, 3 layers, 3 layers, A layer / B layer / C layer / B layer / A layer, 3 layers, 5 layers, etc.) are co-extruded. It is preferably formed by.

The shrink film of the present invention is an oriented film (uniaxially oriented film, biaxially oriented film or multiaxially oriented film) from the viewpoint of shrinkage characteristics. It is preferable that all the resin layers of the A layer, the B layer, and the C layer in the shrink film of the present invention are oriented. When all the resin layers are non-oriented, good shrinkage cannot be obtained. Although the shrink film of the present invention is not particularly limited, a uniaxially oriented film or a biaxially oriented film is preferable, and among these, the uniaxial direction of the film [particularly, the width direction of the film (in the case of a cylindrical shrink label, the circumferential direction of the label). Direction)] is preferred (substantially a uniaxially oriented film in the width direction). It may be a substantially uniaxially oriented film in the longitudinal direction that is strongly oriented in the longitudinal direction of the film (direction perpendicular to the width direction).

In the shrink film of the present invention, the thickness of the A layer (only one layer) is not particularly limited, but is preferably 3 to 15 μm, more preferably 5 to 10 μm. If the thickness of the A layer exceeds 15 μm, the shrinkage stress of the A layer becomes too high, and delamination during shrink processing cannot be suppressed, or the shrinkage may occur rapidly and the finish may be lowered. On the other hand, if the thickness is less than 3 μm, the shrinkage may be insufficient or the strength of the shrink film may be reduced. In particular, when the shrink film of the present invention has a layered structure of 3 types, 5 layers of A layer / B layer / C layer / B layer / A layer, from the viewpoint of obtaining the effects of the present invention, the thickness of the A layer ( The thickness of only one layer) is more preferably 3 to 8 μm, still more preferably 5 to 7.5 μm. In the case of having a laminated structure of the above three types and five layers, delamination may easily occur when the thickness of the A layer exceeds 8 μm.

In the shrink film of the present invention, the thickness of the B layer (thickness of only one layer) is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 1 to 8 μm. If the thickness of the B layer exceeds 10 μm, the shrinkage of the shrink film may be reduced, and if it is less than 0.5 μm, the adhesive strength may be reduced and delamination may easily occur.

In the shrink film of the present invention, the thickness of the C layer (thickness of only one layer) is not particularly limited, but is preferably 10 to 70 μm, more preferably 15 to 50 μm. If the thickness of the C layer exceeds 70 μm, the thermal shrinkage rate may decrease. If the thickness of the C layer is less than 10 μm, the shrinkage stress difference with the A layer becomes too large, and delamination during shrink processing cannot be suppressed, or the shrinkage is rapid. May occur and the finish may be reduced.

In the shrink film of the present invention, the ratio of the total A layer thickness (total thickness of all A layers in the shrink film) to the total C layer thickness (total thickness of all C layers in the shrink film) 100% is It is preferably 40 to 150%, more preferably 50 to 100%. If the total A layer thickness is too small relative to the total C layer thickness, the shrinkage of the shrink film may be insufficient (the thermal shrinkage rate will be reduced) or the shrink strength of the shrink film may be reduced and the processability may be reduced. is there. On the other hand, if the total A layer thickness is too large relative to the total C layer thickness, the contraction stress of the A layer increases, the contraction stress difference between the A layer and the C layer becomes too large, and there is a B layer. In some cases, delamination cannot be suppressed. In addition, since the shrink film of this invention has B layer, even if it is a case where A layer thickness with respect to C layer thickness is comparatively thick, delamination is suppressed and shrinkage, waist strength, and delamination deterrence are compatible. This is preferable.

In the shrink film of the present invention, the ratio of the total B layer thickness (the total thickness of all B layers in the shrink film) to the total C layer thickness of 100% is preferably 5 to 100%, more preferably 10 to 50%. It is. If the total B layer thickness is too thin with respect to the total C layer thickness, the adhesive strength of the B layer may be reduced, and delamination may easily occur. On the other hand, if the total B layer thickness is too large with respect to the total C layer thickness, the strength of the shrinkage of the shrink film may be reduced.

The total thickness of the shrink film of the present invention is not particularly limited, but is preferably 20 to 100 μm, more preferably 20 to 80 μm, still more preferably 20 to 50 μm.

The interlayer strength of the shrink film of the present invention before shrink processing is preferably 0.7 (N / 15 mm) or more, more preferably 1.5 (N / 15 mm) or more. When the interlayer strength is less than 0.7 (N / 15 mm), the resin layers are peeled off at the time of processing (printing process of shrink label) such as printing or processing into a cylindrical shape, resulting in lower productivity. Or a quality problem. The interlaminar strength refers to the interlaminar strength having the lowest interlaminar strength among shrink films in a T-type peel test (according to JIS K 6854-3, tensile speed: 200 mm / min).

The shrinkage rate of the shrink film of the present invention (before shrink processing) in the main orientation 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 35% or more, more preferably 35 to 80%, and still more preferably 40 to 80%. When the thermal shrinkage rate (90 ° C., 10 seconds) is less than 35%, the shrink label is not sufficiently contracted in the process of heat-adhering the shrink label to the container, making it difficult to follow the shape of the container. The finish may be poor for the container. The above-mentioned “main orientation direction” is a direction mainly subjected to a stretching process (a direction having the largest thermal shrinkage), and is generally a longitudinal direction or a width direction, for example, substantially in the width direction. In the case of a film uniaxially stretched (substantially a uniaxially oriented film in the width direction), it is the width direction.

The shrinkage rate (90 ° C., 10 seconds) in the direction perpendicular to the main orientation direction of the shrink film of the present invention (before shrink processing) is not particularly limited, but is preferably −5 to 10%.

The haze (haze) value [conforms to JIS K 7105, converted to 40 μm thickness, unit:%] of the shrink film of the present invention is preferably less than 15%, more preferably less than 5.0%, and still more preferably less than 2.0%. It is. When the haze value is 15% or more, printing is performed on the inside of the shrink film (the side that becomes the container side when the shrink label is attached to the container), and the shrink label that shows the print through the shrink film is the product. In some cases, the printing may become cloudy and the decorativeness may deteriorate. However, even if the haze value is 15% or more, it can be sufficiently used in applications other than the above-described applications that show printing through a shrink film.

The shrink film of the present invention is preferably produced by a melt film forming method. The laminated structure is preferably formed by coextrusion (multilayer extrusion). That is, the shrink film of the present invention is preferably produced by a melt extrusion method (particularly a coextrusion method). More specifically, the shrink film of the present invention is preferably produced by forming an unstretched film (unstretched sheet) by melt extrusion (coextrusion) and then stretching the unstretched film. Further, the surface of the shrink film may be subjected to a conventional surface treatment such as a corona discharge treatment, if necessary.

When a mixed raw material is used as a raw material for forming each resin layer (for example, A layer, B layer, C layer) of the shrink film, the mixing method of each component is not particularly limited. For example, the mixed raw material is prepared by dry blending. Alternatively, each component may be melt-kneaded using a uniaxial or biaxial kneader to obtain a mixed raw material. Moreover, you may use a master pellet (For example, what mixed the specific component with comparatively high density | concentration).

In the melt extrusion (coextrusion), raw materials (resin or resin composition) for forming each resin layer (A layer, B layer, C layer, etc.) are respectively formed in a plurality of extruders each set to a predetermined temperature. And melt extrusion (coextrusion) from a T die, a circular die or the like. At this time, it is preferable to use a manifold or a feed block to form a predetermined layer structure. Further, if necessary, the supply amount may be adjusted using a gear pump, and it is preferable to remove foreign substances using a filter because film tearing can be reduced. The extrusion temperature varies depending on the type of raw material used and is not particularly limited. However, it is preferable that the molding temperature region of the raw material forming each resin layer is close. That is, it is preferable that the extrusion temperature of each resin layer is close. Specifically, the extrusion temperature of the raw material forming the A layer is preferably 200 to 240 ° C., the extrusion temperature of the raw material forming the B layer is 180 to 220 ° C., and the extrusion temperature of the raw material forming the C layer is 190 to 220 ° C. ° C is preferred. Further, the temperature of the junction or die is preferably 200 to 220 ° C. An unstretched laminated film (sheet) can be obtained by quenching the coextruded polymer using a cooling drum (cooling roll) or the like.

Aligned films such as uniaxial orientation and biaxial orientation can be produced by stretching an unstretched laminated film. The stretching can be selected according to the desired orientation, and for example, the longitudinal direction (film production line direction; also referred to as longitudinal direction or MD direction) and the width direction (direction perpendicular to the longitudinal direction; also referred to as lateral direction or TD direction). ) Biaxial stretching, or uniaxial stretching in the longitudinal direction or the width direction. The stretching method may be any method such as a roll method, a tenter method, and a tube method. The stretching conditions in the stretching process vary depending on the type of raw material used and the required characteristics of the shrink film, and are not particularly limited. In general, it is preferably carried out at a stretching temperature of 70 to 110 ° C. (preferably 80 to 95 ° C.) at a stretching ratio of about 2 to 8 times in at least one of the longitudinal direction and the width direction. For example, the film stretched substantially uniaxially in the width direction is, for example, about 1.01 to 1.5 times (preferably 1.05 to 1.3 times) in the longitudinal direction as necessary. After stretching, it is preferable to stretch about 2 to 7 times (preferably 3 to 6.5 times, more preferably 4 to 6 times) in the width direction.

In the shrink film of the present invention, the A layer has an aromatic polyester resin as a main component and is highly shrinkable, so that the shrinkability (high shrinkage rate, high shrinkage stress) of the shrink film is improved, and the wearability to the container is improved. Good finish. In addition, since the A layer is highly rigid, the waist strength of the shrink film is improved. For example, the wearability when the cylindrical shrink label is attached to the container is improved, and problems such as “bending” occur. Hateful. Moreover, when A layer is used as a surface layer, the printability, abrasion resistance, and chemical resistance of the shrink film surface are improved. Since the C layer has a polypropylene resin as a main component, the shrink film has a low specific gravity. In addition, rapid shrinkage of the shrink film can be suppressed and the shrinkage behavior can be moderated, and the handleability during shrink processing is improved. Since the shrink film of the present invention is formed by laminating the A layer and the C layer, it is excellent in shrinkage and workability, and it is possible to achieve both characteristics such as low specific gravity, waist strength, and printability. .

However, the shrinkage behavior (heat shrinkage behavior) and the shrinkage stress (heat shrinkage stress) differ greatly between the A-layer aromatic polyester resin and the C-layer polypropylene resin (the shrinkage stress of the aromatic polyester resin is large). For this reason, when shrink processing (thermal shrinkage processing) is applied to a laminated shrink film having an A layer and a C layer, a difference occurs in the shrinkage behavior between the A layer and the C layer. Delamination easily occurs. The above phenomenon occurs particularly noticeably at the center seal portion when the shrink film is used as a cylindrical shrink label. This is presumably because in the center seal portion, one surface side is fixed by the center seal, so that the influence of the shrinkage of the unfixed surface side resin layer is increased. On the other hand, the present inventors have provided a specific intermediate layer composed mainly of an ethylene-vinyl acetate resin between the A layer and the C layer. Succeeded in improving deterrence (see International Publication No. 2009/084212 pamphlet). However, in the shrink film, when the shrink processing conditions are increased (for example, 90 to 100 ° C., etc.), the intermediate layer may be softened and the delamination inhibiting effect may be lowered.

On the other hand, in the shrink film of the present invention, a constituent unit derived from ethylene, a constituent unit derived from methyl methacrylate, and a constituent unit derived from 1-butene are contained in the layer between the A layer and the C layer. B layers are provided, each of which is limited to a specific range. By the structural unit derived from ethylene, the behavior of the B layer at the time of melting is preferably controlled, thereby improving the formability of the layer and the delamination deterrence at room temperature and during heating. Further, the structural unit derived from methyl methacrylate improves the flexibility of the B layer and the adhesiveness (tackiness) with the A and C layers, thereby improving the followability to the A and C layers. Further, the heat resistance of the B layer is improved by the structural unit derived from 1-butene. For this reason, the shrink film of the present invention is a shrink film in which the A layer and the C layer are laminated, and has excellent delamination deterrence during shrink processing, particularly shrinkage under relatively high temperature conditions and rapid heating conditions. The delamination deterrence at the time of the outstanding shrink process with respect to a process can be exhibited.

[Shrink label]
The shrink film of the present invention can be preferably used as a shrink label. In the present specification, a shrink label including the shrink film of the present invention may be referred to as “shrink label of the present invention”. As a shrink label of this invention, the shrink label which has a printing layer in the at least one surface side of the shrink film (base material) of this invention is mentioned, for example. In addition to the printed layer, the shrink label of the present invention includes a protective layer, an anchor coat layer, a primer coat layer, an adhesive layer (for example, a pressure-sensitive adhesive layer, a heat-sensitive adhesive layer, etc.), a coating layer, and the like. It may have, and may have layers, such as a nonwoven fabric and paper, further. Examples of the layer structure of the shrink label of the present invention include, for example, printing layer / A layer / B layer / C layer / B layer / A layer, printing layer / A layer / B layer / C layer / B layer / A layer / printing. Layers and the like are preferred. In addition, the shrink film of this invention can also be used as a shrink label by itself even when a printing layer is not provided. In other words, the shrink label of the present invention may be a shrink label made only of the shrink film of the present invention.

The print layer is a layer displaying, for example, a product name, an illustration, and handling precautions. The printing layer is formed, for example, by applying printing ink. The coating method is preferably an off-line coating in which coating is performed using a known and commonly used printing method after forming a shrink film from the viewpoint of productivity, workability, and the like. As a printing method, a conventional method can be used, and for example, gravure printing or flexographic printing is preferable. The printing ink used for forming the printing layer includes, for example, a pigment, a binder resin, a solvent, and other additives. The binder resin is not particularly limited. For example, acrylic, urethane, polyamide, vinyl chloride-vinyl acetate copolymer, cellulose, and nitrocellulose resins can be used alone or in combination. As the pigment, a white pigment such as titanium oxide (titanium dioxide), an indigo pigment such as copper phthalocyanine blue, carbon black, aluminum flakes, mica (mica), and other colored pigments can be selected and used according to the application. In addition, extender pigments such as alumina, calcium carbonate, barium sulfate, silica, and acrylic beads can also be used as pigments for the purpose of adjusting gloss. As said solvent, what is normally used for printing inks, such as organic solvents, such as toluene, xylene, methyl ethyl ketone, ethyl acetate, methyl alcohol, ethyl alcohol, and isopropyl alcohol, and water can be used, for example.

The printing layer is not particularly limited, but may be an active energy ray-curable resin layer such as visible light, ultraviolet light, or electron beam. This is effective for preventing deformation of the film due to excessive heat.

The thickness of the printing layer is not particularly limited, but is preferably 0.1 to 10 μm, for example. If the thickness is less than 0.1 μm, it may be difficult to provide a uniform printing layer, and partial “blur” may occur, resulting in a loss of decorativeness or printing as designed. May be difficult. In addition, when 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 easily peels off. . Moreover, the rigidity of a printing layer becomes high and a printing layer may become difficult to follow shrinkage | contraction of a shrink film at the time of shrink processing.

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 effective for the cylindrical shrink label from the viewpoint that it is most effective in suppressing delamination (attachment delamination) at the center seal portion when the cylindrical shrink label is attached to the container. Preferably used. That is, the shrink label of the present invention is preferably a cylindrical shrink label.

The shrink label of the present invention may be processed into a cylindrical shrink label. For example, the shrink label is formed in a cylindrical shape so that the main orientation direction is the circumferential direction. Specifically, a shrink label having a predetermined width in the main orientation direction is formed into a cylindrical shape by overlapping both ends of the main orientation direction so that the front side of the shrink label is an outer surface (outer side), and one side of the label Apply a solvent or adhesive such as tetrahydrofuran (THF) or an adhesive (hereinafter sometimes referred to as “adhesive etc.”) to the inner surface of the belt with a width of about 2 to 4 mm on the edge. Adhere to the outer surface of the other side edge to obtain a cylindrical shrink label. In addition, it is preferable that the printing layer is not provided in the part which apply | coats said adhesive agent etc., and the part to adhere | attach. In the above description, the “front side” of the shrink label means the side viewing the design of the label (the side of the surface where the design looks correct). In addition, the “outer surface” of the shrink label means the surface on the side that is not in contact with the container (the side opposite to the container, that is, the outside of the cylinder) when the shrink label is attached to the container. "Means the surface on the side in contact with the container (container side).

In addition, when providing the perforation for label cutting to a cylindrical shrink label, the perforation of predetermined length and a pitch is formed in the 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 process stage for perforating can be appropriately selected after the printing process and before and after the cylindrical processing process.

The center seal strength of the cylindrical shrink label is preferably 2N / 15 mm or more. If the center seal strength is less than 2 N / 15 mm, the center seal portion may be peeled off after processing or commercialization, thereby reducing productivity and causing label dropout.

The shrink label of the present invention is not particularly limited, but is used as a labeled container by being attached to a container such as a beverage container. In addition, the shrink label of this invention may be used for adherends other than a container. The shrink label of the present invention (in particular, the cylindrical shrink label) is attached to the container by, for example, placing the front side on the opposite side of the container and heat shrinking, thereby attaching a labeled container (the shrink label of the present invention). A labeled container) is obtained. Examples of the container include a soft drink bottle such as a PET bottle, a milk bottle for home delivery, a food container such as a seasoning, a bottle for alcoholic beverages, a pharmaceutical container, a detergent container, a chemical container such as a spray, and a cup noodle container. Etc. 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 above-mentioned container with a label 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. The heat treatment is not particularly limited, but is preferably performed in a temperature range in which the temperature of the shrink film is 85 to 97 ° C. (particularly 90 to 95 ° C.). The shrink film of the present invention can be heat-treated particularly at a high temperature (90 to 95 ° C.), so that it can be used for containers that require high shrinkage. The treatment time for the heat treatment is preferably 4 to 20 seconds from the viewpoint of productivity and economy.

Even if the shrink label (especially cylindrical shrink label) using the shrink film of the present invention is attached to a container by shrink processing (heat shrink processing), even when subjected to shrink processing under high temperature conditions, In particular, the center seal portion is preferable because delamination (mounting delamination) hardly occurs.

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

Table 1 shows the types and contents of the A layer raw material, the B layer raw material, and the C layer raw material in the examples and comparative examples, the structural unit derived from ethylene in the B layer, the structural unit derived from methyl methacrylate, 1- Content of the structural unit derived from butene was described. Moreover, the thickness (all layer thickness) of the obtained shrink film, layer thickness ratio, the weight average molecular weight of B layer, the evaluation result, etc. were shown.

Table 2 shows the structural units derived from ethylene in the compounds of ethylene-methyl methacrylate copolymer (Aklift WK307) and ethylene-1-butene copolymer (Excellen VL700) used as the raw material for layer B, methyl methacrylate. Content of structural unit derived from 1 and content of structural unit derived from 1-butene, and other physical properties [weight average molecular weight, melting point, T (tan δ ≧ 1), MFR (190 ° C., 2.16 kgf), density] showed that.

Example 1
As a raw material constituting the A layer (A layer raw material), 100% by weight of CHDM-modified amorphous aromatic polyester resin ("EMBRACE LV" manufactured by Eastman Chemical Co., Ltd., CHDM copolymerized PET) was used.
As raw materials constituting the B layer (B layer raw material), ethylene-methyl methacrylate copolymer (“Aclift WK307” manufactured by Sumitomo Chemical Co., Ltd.) 80% by weight, and ethylene-1-butene copolymer (Sumitomo Chemical Co., Ltd.) ) “Excellen VL700”)) 20% by weight was used. As shown in Table 2, the ethylene-methyl methacrylate copolymer (Aklift WK307) is an ethylene-methyl methacrylate copolymer containing 75% by weight of structural units derived from ethylene and 25% by weight of structural units derived from methyl methacrylate. It is a polymer (EMMA). The ethylene-1-butene copolymer (Excellen VL700) contains 86.9 wt% of structural units derived from ethylene and 13.1 wt% of structural units derived from 1-butene. It is a copolymer.
As the raw material constituting the C layer (C layer raw material), 60% by weight of the mixed raw material and 40% by weight of the recovered raw material (recycled material) were used. The above mixed raw materials were 70% by weight of polypropylene resin ("Wintech WFX6" manufactured by Nippon Polypro Co., Ltd., metallocene catalyst propylene-ethylene random copolymer), polyethylene resin ("Kernel KF260T manufactured by Nippon Polyethylene Co., Ltd.)"", LLDPE) 5 wt% and petroleum resin (" Arcon P125 "manufactured by Arakawa Chemical Industries, Ltd.) 25 wt%. Moreover, the said collection | recovery raw material arises from manufacture of the shrink film of a present Example (what is called collection | recovery raw material by self-collection).

The layer A raw material was charged into an extruder a heated to 220 ° C., the layer B raw material was charged into an extruder b heated to 180 ° C., and the layer C raw material was charged into an extruder c heated to 200 ° C. Melt extrusion (coextrusion) was performed using the three extruders. The resin extruded from the extruder c becomes the center layer, the resin extruded from the extruder b becomes the layers (intermediate layer) on both sides of the center layer, and the resin extruded from the extruder a becomes the layers on both sides (surface layer). Thus, after merging using a merging block and extruding from a T die (slit interval: 1 mm), it was rapidly cooled on a casting drum cooled to 25 ° C. to obtain a three-kind five-layer laminated unstretched film.
Next, the unstretched film whose thickness was adjusted was stretched 5.7 times at 88 ° C. in the width direction to obtain a shrink film (substantially a uniaxially oriented film in the width direction). The total thickness (total layer thickness) of the obtained shrink film was 35 μm, and the layer thickness ratio (A layer: B layer: C layer: B layer: A layer) was 7: 2: 17: 2: 7.

Examples 2 to 5 and Comparative Examples 1 to 3
As shown in Table 1, the contents of ethylene-methyl methacrylate copolymer and ethylene-1-butene copolymer in the raw materials for layer B, the total layer thickness (shrink film thickness), the layer thickness ratio, etc. were changed. In the same manner as in Example 1, a shrink film was obtained.

Comparative Example 4
Shrink film was prepared in the same manner as in Example 3 except that the material for layer B was changed to 100% by weight of an ethylene-vinyl acetate copolymer (Evalate K2010 manufactured by Sumitomo Chemical Co., Ltd., vinyl acetate content: 25% by weight). Got.

(Evaluation)
The shrink films obtained in Examples and Comparative Examples and the raw materials used in Examples and Comparative Examples were evaluated by the following methods.
In addition, the shrink film after forming into a film, continuing collection | recovery (self-collection) for 40 hours or more was used for evaluation.

(1) Delamination deterrence (delamination deterrence at the center seal during shrink processing)
The shrink film (size: longitudinal direction 104 mm × width direction 235 mm) obtained in Examples and Comparative Examples was rolled into a cylindrical shape so that the width direction of the shrink film was the circumferential direction (cylinder circumference: 228 mm). And center seal (center seal width: 4 mm) with tetrahydrofuran (THF) to obtain a cylindrical shrink label. Next, the above-mentioned cylindrical shrink label is manually attached to a container (cylindrical PET bottle with a circumference of 219 mm on the trunk), and is heat-shrinked (shrink processed) for 5 seconds in a 94 ° C. steam tunnel, with a label. A container was obtained.
For each shrink film obtained in each example and comparative example, 2400 labeled containers were produced and used for evaluation.
Observe the center seal part of the above-mentioned container with a label, and if there is “delamination” of 10 mm or more in the longitudinal direction and 1 mm or more in the width direction, it is considered to be a defective product and is attached as follows. Judgment was made. Note that delamination occurred between the A layer and the B layer.
Good mounting delamination deterrence (◯): Out of 2400, the number of defective products is less than 50.
Wearing delamination deterrence defect (x): Out of 2,400, 50 or more defective products.

(2) Stretchability The shrink films (size: longitudinal direction 300 mm × width direction 100 mm) obtained in Examples and Comparative Examples were visually observed, and in the case where no whitening was observed, good stretchability (◯), whitening was observed. The case where it was made was determined to be poor stretchability (x).

(3) T of layer B (tan δ ≧ 1) (dynamic viscoelasticity measurement)
The dynamic viscoelasticity measurement was performed under the following conditions using the resin used as the B layer material in Examples and Comparative Examples as a sample.
In the dynamic viscoelastic curve (loss tangent curve, temperature-tan δ curve) obtained by dynamic viscoelasticity measurement, the temperature at which tan δ = 1 when the curve rises from less than 1 to 1 or more is expressed as “T ( tan δ ≧ 1) ”.
(Measurement equipment, measurement conditions)
Apparatus: Seiko Instruments Inc. "EXSTAR6000"
DMS6100 "
Frequency: 1Hz
Measurement temperature: Normal temperature (30 ° C.) to 120 ° C. (If measurement was not possible up to 120 ° C., measurement was performed up to a measurable temperature.)
Temperature increase rate: 2 ° C./min Measurement sample: Sheet of 250 to 350 μm thickness formed by melting resin pellets at 200 ° C. Ethylene-methyl methacrylate copolymer (Aklift WK307) and ethylene-1-butene copolymer Each of (Excellen VL700) was also evaluated in the same manner as described above (the evaluation results are shown in Table 2).

(4) Thermal shrinkage in main orientation direction (90 ° C., 10 seconds)
120 mm in length in the measurement direction (main orientation direction: width direction of the shrink film in the examples and comparative examples) from the shrink film (before shrinkage processing) obtained in the examples and comparative examples, sample piece A rectangular sample piece having a width of 5 mm was prepared.
The sample piece was heat-treated in warm water at 90 ° C. for 10 seconds (under no load), the difference between the marked line intervals before and after the heat treatment was read, and the thermal shrinkage rate (90 ° C., 10 seconds) was calculated by the following formula. .
Thermal shrinkage (90 ° C., 10 seconds) (%) = (L ₀ −L ₁ ) / L ₀ × 100
L ₀ : Mark interval before heat treatment (main orientation direction)
L ₁ : Marking interval after heat treatment (main orientation direction)

As can be seen from Table 1, the shrink film (Example) of the present invention was excellent in delamination resistance and was not easily delaminated even when subjected to high-temperature shrink processing. Furthermore, the stretchability was also excellent. On the other hand, the shrink film containing no structural unit derived from 1-butene in the B layer (Comparative Examples 1, 2, and 4) tends to cause delamination when subjected to high-temperature shrink processing, and suppresses mounting delamination. Was inferior. In addition, the shrink film (Comparative Example 3) in which the content of the structural unit derived from methyl methacrylate in the layer B is small and the content of the structural unit derived from 1-butene is large is inferior in stretchability, and the shrink film is whitened. did. Furthermore, when shrink processing was performed, delamination was likely to occur, and the delamination prevention property was inferior.

Further, “fine wrap NTV” manufactured by DIC Graphics Co., Ltd. was gravure printed on one side of the shrink film obtained in Example 1 to form a printed layer having a thickness of 2 μm to obtain a shrink label.
Furthermore, a labeled container was obtained in the same manner as described in the above-mentioned mounting delamination inhibiting property.
The obtained shrink label was excellent in surface printability, and the labeled container had an excellent finish.

Claims

A resin layer (A layer) containing an aromatic polyester resin;
Resin layer (B layer) containing 60 to 78 wt% of structural units derived from ethylene, 18 to 24 wt% of structural units derived from methyl methacrylate, and 1 to 3.5 wt% of structural units derived from 1-butene When,
A resin layer (C layer) containing a polypropylene resin,
A shrink film characterized by having a laminated structure in which the layers are laminated in the order of A layer / B layer / C layer without interposing other layers.
The layer B comprises at least one ethylene copolymer selected from the group consisting of an ethylene-methyl methacrylate copolymer, an ethylene-1-butene copolymer, and an ethylene-1-butene-methyl methacrylate copolymer. The shrink film according to claim 1, wherein the shrink film is a resin layer.
The shrink film according to claim 1 or 2, having a laminated structure in which the layers are laminated in the order of A layer / B layer / C layer / B layer / A layer without any other layers.
A shrink label including the shrink film according to any one of claims 1 to 3.