JP4980802B2 - Shrink film and shrink label - Google Patents

Description

  The present invention relates to a heterogeneous laminated shrink film having improved interlayer strength. More specifically, the present invention relates to a shrink film having a film layer made of a polyolefin resin and a film layer made of a polyester resin, having a low specific gravity and excellent shrinkage characteristics, and further having a superior interlayer strength. Moreover, it is related with the shrink label which provided the printing layer in this shrink film.

  Currently, in the field of plastic films, different types of laminated films in which different resin materials are laminated are widely used for the purpose of imparting various different functions to the film. For example, a heat-shrinkable film in which a polyester resin and a polystyrene resin are laminated is known (for example, see Patent Documents 1 to 6).

  On the other hand, from the viewpoint that the specific gravity is small and light, and it is easy to separate from PET bottles using the difference in specific gravity at the time of collection, polyolefin resin is used as the center layer, and further, the adhesive resin layer is interposed. By providing a surface layer made of non-polyolefin resin such as polyester resin, heat shrinkability consisting of a laminated film of polyolefin resin and polyester resin with improved properties such as low temperature shrinkage, center sealability, printability, etc. Label films are known (see, for example, Patent Document 7).

  However, the laminated film made of polyolefin resin and polyester resin cannot be said to have sufficient interlayer strength. For example, when used for shrink label applications, labeling is triggered by the center-sealed part (adhesive part) when heat-shrinked. There was a problem such as delamination at the end. That is, a shrink film having a laminated structure using a polyolefin resin as a center layer and a polyester resin as a surface layer, and having an excellent shrink film having both low density, shrinkage characteristics and practically suitable interlayer strength can be obtained. The current situation is not.

JP 2006-159901 A JP 2006-159902 A JP 2006-159903 A JP 2006-159906 A JP 2006-15745 A JP 2006-123482 A JP 11-262981 A

  An object of the present invention is to provide a shrink film exhibiting high interlayer strength in a laminated shrink film of different polymers of polyolefin resin and polyester resin. Another object of the present invention is to provide a shrink label using the shrink film.

  As a result of investigation, the present inventors have a surface layer composed of an amorphous polyester resin, an intermediate layer composed of a polyolefin resin having a reactive functional group, and a central layer composed of a polyolefin resin. It has been found that an excellent shrink film having both low density, shrinkage characteristics and interlaminar strength that can withstand practical use can be obtained by a three-kind five-layer laminated shrink film.

  However, it has been found that the above-mentioned shrink film also tends to deteriorate interlaminar strength and shrinkage characteristics when stretched at a high magnification in order to correspond to a high shrink type shrink label application. That is, for high-shrinkage type shrink label applications used in complex container shapes, further improvements in interlayer strength and shrinkage characteristics are required.

  Therefore, as a result of intensive studies to achieve the above object, the present inventors have found that styrene having a specific monomer composition is interposed between a central layer composed of a polyolefin resin and a surface layer composed of a polyester resin. Stretched at a high magnification in order to obtain an excellent interlayer strength, especially a high shrink type shrink film by adopting a laminated structure of 3 types and 5 layers with an intermediate layer composed of a thermoplastic elastomer and / or its derivatives The present inventors have found that a heterogeneous laminated film having a high interlayer strength can be obtained even when treated, and thus completed the present invention.

That is, the present invention includes a surface layer (A layer) composed mainly of an amorphous polyester resin, 10 to 45 % by weight of a styrene monomer as a monomer component, and 55 to 90% by weight of a conjugated diene. % including styrene-based thermoplastic elastomer, and / or intermediate layer consisting of a derivative thereof as a main component (B layer), and was polymerized using polypropylene and metallocene catalysts obtained by polymerization using a metallocene catalyst The center layer (C layer) composed mainly of a polyolefin resin selected from the group consisting of the propylene-α-olefin random copolymer obtained as described above is A layer / B layer / C layer / B layer / In the order of layer A, the non-crystalline polyester-based resin is laminated without any other layer. Reethylene terephthalate, which is a modified polyethylene terephthalate in which a part of the dicarboxylic acid component and / or diol component is replaced with another dicarboxylic acid component and / or diol component, and is C relative to 100% of the total thickness of the shrink film. A shrink film having a layer thickness of 40 to 95% is provided.

  Furthermore, the present invention provides the above-mentioned shrink film in the styrene thermoplastic elastomer constituting the B layer, wherein the styrene monomer is styrene and the conjugated diene is 1,3-butadiene and / or isoprene.

Furthermore, this invention provides the said shrink film in which C layer contains a tackifier and / or an olefinic elastomer further.

Further, in the present invention, the B layer further contains a tackifier, and the addition amount of the tackifier in the B layer is 5 to 30% by weight with respect to the total weight of the resin composition constituting the B layer. The shrink film is provided.

  Furthermore, this invention provides the shrink label which provided the printing layer in the at least one surface side of the said shrink film.

  Since the shrink film of the present invention has a central layer made of a polyolefin-based resin, when it is used as a shrink label with a small specific gravity, it can be easily separated from a PET bottle or the like by utilizing the difference in specific gravity at the time of recovery. Furthermore, by having a surface layer made of a polyester-based resin, it has excellent shrinkage characteristics, strength characteristics, and printability. Moreover, the interlayer strength of each layer is high, and troubles due to delamination do not occur in the manufacturing process and distribution process. In particular, even in the case of a highly shrinkable shrink film stretched at a high magnification, a high interlayer strength can be maintained. It is also excellent in transparency. For this reason, it is useful as a shrink label attached to a container such as a PET bottle.

  Below, the shrink film of this invention is demonstrated in detail.

The shrink film of the present invention includes a surface layer (hereinafter referred to as “A layer”) composed mainly of a polyester-based resin, an intermediate layer composed mainly of a styrene-based thermoplastic elastomer and / or a derivative thereof ( Hereinafter, it has at least a central layer (hereinafter referred to as “C layer”) composed mainly of a polyolefin-based resin.
The resin composition forming the A layer is “resin composition A”, the resin composition forming the B layer is “resin composition B”, and the resin composition forming the C layer is “resin composition C”. Sometimes called. The term “main component” as used in the present application means that the content in each layer is 50% by weight or more based on the total weight of the resin composition forming the layer, unless otherwise specified. More preferably, it means 60% by weight or more.

  In the shrink film of the present invention, the A to C layers are in the order of A layer (surface layer) / B layer (intermediate layer) / C layer (center layer) / B layer (intermediate layer) / A layer (surface layer). It has a three-kind five-layer laminated structure laminated without interposing other layers. In addition, although it is preferable that A layers and B layers which were each provided in the both sides of C layer are the layers which respectively consist of the same resin composition, in the range which does not impair the prescription | regulation and effect of this invention. The layers may have different compositions (for example, A1 layer and A2 layer). The shrink film of the present invention may be a film composed of the above-mentioned 3 types and 5 layers, or a layer that can be provided in-line in the film forming process of the above 3 types and 5 layers. You may have layers other than a seed 5 layer composition film. Examples of such a layer include coating layers such as an anchor coat layer, an easy adhesion layer, and an antistatic agent layer.

[Surface layer (A layer)]
The surface layer (A layer) in the shrink film of the present invention is composed mainly of an amorphous polyester resin. The amorphous polyester resin is a substantially amorphous polyester resin.

  If the said amorphous polyester-type resin is substantially amorphous, it will not specifically limit, For example, the various polyester comprised by the dicarboxylic acid component and a diol component is mentioned.

  Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 5-t-butylisophthalic acid, 4,4′-biphenyldicarboxylic acid, trans-3,3′-stilbene dicarboxylic acid, and trans-4,4. '-Stilbene dicarboxylic acid, 4,4'-dibenzyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2, 7-naphthalenedicarboxylic acid, 2,2,6,6-tetramethylbiphenyl-4,4′-dicarboxylic acid, 1,1,3-trimethyl-3-phenylindene-4,5-dicarboxylic acid, 1,2- Aromatic dicals such as diphenoxyethane-4,4′-dicarboxylic acid, diphenyl ether dicarboxylic acid, and substituted products thereof Acid; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, Aliphatic dicarboxylic acids such as heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, icosanedioic acid, docosanedioic acid, 1,12-dodecanedioic acid, and their substitutions; 1,4-decahydronaphthalenedicarboxylic acid, 1,5-decahydronaphthalenedicarboxylic acid, 2,6-decahydronaphthalenedicarboxylic acid, cis-1,4-cyclohexanedicarboxylic acid, trans-1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and these And alicyclic dicarboxylic acids such as substitution products thereof. These dicarboxylic acid components can be used alone or in combination of two or more.

  Examples of the diol component include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 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, polyethylene glycol, polypropylene Aliphatic diols such as glycol; 1,2-cyclohexanedimethanol, 1,3-cyclohexane Cycloaliphatic diols such as sandimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol; 2,2-bis (4′-β-hydroxyethoxydiphenyl) Examples thereof include ethylene oxide adducts of bisphenol compounds such as propane and bis (4′-β-hydroxyethoxyphenyl) sulfone, and aromatic diols such as xylylene glycol. These diol components can be used alone or in combination of two or more.

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

  As an amorphous polyester resin, 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 is used. Preferred examples include modified PET substituted with other dicarboxylic acid components and / or diol components. Examples of the dicarboxylic acid component used in the modified PET include cyclohexane dicarboxylic acid, adipic acid, and isophthalic acid. Examples of the diol component include 1,4-cyclohexanedimethanol (CHDM), neopentyl glycol (NPG), and diethylene glycol.

  Specifically, as the modified PET, terephthalic acid is used as the dicarboxylic acid component, EG as the diol component, and copolyester using CHDM as the copolymer component (hereinafter referred to as CHDM copolymerized PET or CHDM modified PET). And copolyesters using neopentyl glycol (NPG) as a copolymerization component (hereinafter referred to as NPG copolymerized PET or NPG-modified PET) are preferred from the viewpoints of cost, productivity, and the like. Furthermore, diethylene glycol may be copolymerized from the viewpoint of improving low-temperature shrinkage.

In the modified PET, the copolymerization ratio of the copolymerization component used in the modification (ratio of copolymerization dicarboxylic acid component to the total dicarboxylic acid component or the proportion of copolymerized Jio Le Ingredient for all Jio Le Ingredients) An interlayer strength From the viewpoint of further improving the content, it is preferably 15 mol% or more (for example, 15 to 40 mol%). Among them, for example, in the case of CHDM copolymerized PET, the proportion of CHDM copolymerization is 20 to 40 mol% (EG is 60 to 80 mol%) in the diol component (that is, with respect to 100 mol% of terephthalic acid). More preferably, it is 25-35 mol% (EG is 65-75 mol%). Moreover, in the case of NPG copolymerized PET, 15-40 mol% (EG is 60-85 mol%) in a diol component is preferable. Further, a part (preferably 10 mol% or less) of the EG component may be replaced with diethylene glycol.

  As described above, by modifying the polyester to be amorphous, the fluidity at the melting temperature of the layer A can be lowered and the fluidity behavior of the layer B can be brought close to. improves.

  The degree of crystallinity of the amorphous 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. is there. Further, the one that hardly shows the melting point (melting peak) by the DSC method (that is, the degree of crystallinity is 0%) is most preferable. The crystallinity can be calculated from the value of heat of crystal fusion obtained by DSC measurement using a sample with a clear crystallinity fixed 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 polyester resin can be obtained by subtracting the melting peak of the resin to be mixed. That's fine.

  The weight average molecular weight of the amorphous polyester resin is preferably 50000 to 90000, more preferably 60000 to 80000, from the viewpoint of controlling the melting behavior within a preferable range. Furthermore, in the case of NPG copolymerized PET, it is preferably 50000 to 80000, more preferably 60000 to 70000.

  The IV value (intrinsic viscosity) of the amorphous polyester resin is preferably 0.70 (dl / g) or more, more preferably 0.7 to 0.9 (dl / g), from the viewpoint of interlayer strength. More preferably, it is 0.75-0.85 (dl / g). The glass transition temperature (Tg) of the amorphous polyester resin is preferably 70 to 100 ° C., more preferably 70 to 80 ° C., from the viewpoint of shrinkage suitability.

  As the amorphous polyester-based resin, existing products can be used. For example, “Easter Polymer”, “EMBRACE” (above, CHDM copolymerized PET) manufactured by Eastman Chemical; Bell Polyester Products Co., Ltd. “Bellepet” (NPG copolymerized PET, etc.) manufactured by the Company is available on the market.

  The content of the amorphous polyester resin with respect to the total weight of the resin composition constituting the A layer of the present invention is preferably 50 to 100% by weight, more preferably from the viewpoint of shrinkability (shrinkage ratio), specific gravity and the like. 80 to 100% by weight.

  For layer A, if necessary, other additives such as lubricants, fillers, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, colorants, pinning agents (alkaline earth metals) ) And the like.

[Intermediate layer (B layer)]
The intermediate layer (B layer) in the shrink label of the present invention is composed mainly of a polystyrene-based thermoplastic elastomer and / or a derivative thereof. The polystyrene-based thermoplastic elastomer is a copolymerized elastomer composed of a styrene-based monomer and a conjugated diene as essential monomer components.

  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 particularly preferable from the viewpoint of physical properties such as strength and moldability. In addition, these styrenic monomers may be used independently and may use 2 or more types together.

  The conjugated diene is not particularly limited. For example, 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, Examples include 1,3-hexadiene and chloroprene. Among these, 1,3-butadiene and isoprene are particularly preferable from the viewpoint of imparting elasticity and imparting polarity. In addition, these conjugated dienes may be used independently and may use 2 or more types together.

  In the styrenic thermoplastic elastomer, the content of the styrenic monomer is 10 to 60% by weight, preferably 20 to 50% by weight, more preferably 20%, based on the total weight of the monomer components. ~ 45 wt%. On the other hand, content of the said conjugated diene is 40 to 90 weight% with respect to the total weight of a monomer component, Preferably it is 50 to 80 weight%, More preferably, it is 55 to 80 weight%. When the content of the styrenic monomer is less than 10% by weight (or when the content of the conjugated diene exceeds 90% by weight), the resin composition B becomes too soft, so that molding becomes difficult. Further, when the content of the conjugated diene is less than 40% by weight (or when the content of the styrene monomer exceeds 60% by weight), the adhesion with the polyolefin resin (C layer) is lowered. .

  The styrenic thermoplastic elastomer may contain monomer components other than the styrenic monomer and conjugated diene as long as the effects of the present invention are not impaired. Examples of such monomer components include vinyl monomers and polymerizable unsaturated carboxylic acid ester copolymers.

  For the B layer in the shrink film of the present invention, a derivative of the styrene thermoplastic elastomer may be used together with the styrene thermoplastic elastomer or in place of the styrene thermoplastic elastomer. Preferred examples of the styrene thermoplastic elastomer derivative include hydrogenated products obtained by hydrogenating styrene thermoplastic elastomers.

  Moreover, the modified material which modified | denatured the styrenic thermoplastic elastomer and its hydrogenated substance, and introduce | transduced the reactive functional group may be sufficient. The reactive functional group is a functional group that reacts or interacts with the ester bond portion of the polyester (such as a hydrogen bond), and is not particularly limited, and examples thereof include a carboxyl group (including a carboxylic acid anhydride), a hydroxyl group, and an oxazoline. Group, isocyanate group, epoxy group and the like. Among these, from the viewpoint of improving interlayer strength, a dicarboxylic anhydride group (dicarboxylic anhydride modified) is preferable, and a maleic anhydride group (maleic anhydride modified) is particularly preferable. The term “modified” includes both “reactive functional groups introduced into the polymer main chain by grafting” and “introduced by copolymerization”.

  The form of copolymerization of the styrenic thermoplastic elastomer is not particularly limited, such as a random copolymer, a block copolymer, and an alternating copolymer, but a block copolymer is preferred, and a styrene block (S) -conjugated diene is preferred. Block (D) type, SDS type, DSD type, SDS type, etc. are mentioned. Further, it may be a hydrogenated product of the copolymer.

Specific examples of the styrenic thermoplastic elastomer used for the B layer in the shrink film of the present invention include, for example, a styrene-butadiene block copolymer (SBS), a styrene-isoprene block copolymer (SIS), and a styrene- Examples thereof include butadiene-isoprene block copolymer (SBIS). Specific examples of styrene thermoplastic elastomer derivatives include hydrogenated styrene thermoplastic elastomers such as styrene-ethylene / butylene block copolymers (SEBS) and styrene-ethylene / propylene copolymers (SEPS). And modified hydrogenated styrene thermoplastic elastomers such as maleic anhydride-modified SEBS and maleic anhydride-modified SEPS. Of these, styrene-ethylene / butylene block copolymer (SEBS) is most preferable.

  The weight average molecular weight of the styrenic thermoplastic elastomer or derivative thereof is preferably 100,000 to 500,000, more preferably 200,000 to 400,000 from the viewpoint of fluidity during layer formation.

  As the styrenic thermoplastic elastomer or derivative thereof, commercially available products may be used. For example, “Tufprene”, “Asaprene” (above, styrene thermoplastic elastomer) manufactured by Asahi Kasei Chemicals Corporation, Asahi Kasei Chemicals Corporation. "Tuftec H" manufactured by Kuraray Co., Ltd. "Septon" manufactured by Kuraray Co., Ltd., "Hibler" manufactured by Kuraray Co., Ltd. (Hydrogenated styrene thermoplastic elastomer), "Tuftec M" manufactured by Asahi Kasei Chemicals Co., Ltd. (modified with maleic anhydride) Hydrogenated styrene-based thermoplastic elastomer).

  The content of the styrenic thermoplastic elastomer and its derivative with respect to the total weight of the resin composition constituting the B layer is 50% by weight or more, preferably 60 to 100% by weight, more preferably from the viewpoint of interlayer strength. 70 to 100% by weight, more preferably 90 to 100% by weight.

  The layer B may contain a tackifier such as petroleum resin or terpene resin in order to prevent a decrease in adhesion due to heat when shrinking. Examples of the tackifier 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 resin), petroleum resin (aliphatic, aromatic, alicyclic) and the like. Among these, petroleum resin is preferable. A tackifier can be used individually or in combination of 2 or more types. The addition amount in the case of adding a tackifier is preferably 5 to 30% by weight, more preferably 10 to 20% by weight, based on the total weight of the resin composition constituting the B layer. If the amount added exceeds 30% by weight, the resin may become too soft and molding may be difficult. Moreover, if it is less than 5 weight%, the effect of addition may be small. As the tackifier, “Arcon” manufactured by Arakawa Chemical Co., Ltd., “Clearon” manufactured by Yashara Chemical Co., Ltd., “Imabe” manufactured by Idemitsu Kosan Co., Ltd., and the like are available as commercial products.

  Further, in the B layer, for the purpose of improving the interlayer strength, the recovered raw material and the resin component (amorphous polyester resin) constituting the A layer and the C layer are constituted within a range not impairing the effects of the present invention. A resin component (polyolefin resin) may be included. The compounding quantity in that case is about 1 to 30 weight% with respect to the total weight of the resin composition which comprises B layer. Recovered raw materials are non-product parts such as before and after commercialization and film edges, remaining parts when product films are collected from intermediate products, non-standard film waste, polymer waste, and recycled raw materials ( However, it is limited to those resulting from the manufacture of the shrink film of the present invention).

[Center layer (C layer)]
The center layer (C layer) in the shrink label of the present invention is composed mainly of a polyolefin resin. Although it does not specifically limit as said polyolefin resin, For example, homopolymers, such as polyethylene (PE), polypropylene (PP), polybutylene, polymethylpentene (PMP); Ethylene-alpha-olefin copolymer, propylene-alpha -Copolymers such as olefin copolymers (including olefin elastomers); copolymers of cyclic olefins and α-olefins (ethylene, propylene, etc.) or graft modified products thereof, ring-opening polymers of cyclic olefins or the like Examples thereof include amorphous cyclic olefin polymers such as hydrogenated products or graft-modified products thereof. Among these, from the viewpoint of interlayer strength, polypropylene, propylene-α-olefin random copolymer, and ethylene-α-olefin copolymer are preferable, and polypropylene (metallocene catalyst obtained by polymerization with a metallocene catalyst is particularly preferable. Type polypropylene), a propylene-α-olefin random copolymer. Moreover, these polyolefin resin can be used individually or in mixture of 2 or more types.

  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 include α-olefins having about 4 to 20 carbon atoms such as octene, 1-nonene, 1-decene. These copolymerization components can be used alone or in admixture of two or more. Among these, preferred are ethylene-propylene random copolymers having ethylene as a copolymerization component. In this ethylene-propylene random copolymer, the ratio of ethylene and propylene is, for example, (the former / the latter (weight ratio) = 2/98 to 5/95 (preferably 3/97 to 4.5 / 95.5)). It can be selected from a range of degrees.

  Furthermore, the ethylene-propylene random copolymer is a copolymer obtained by copolymerization using a metallocene catalyst in that it can improve the low temperature shrinkage of about 60 to 80 ° C. and the fit to the container during heat shrinkage. Polymers are preferred. In addition, those having an isotactic index of 90% or more are preferable from the viewpoint of low temperature shrinkage and film waist strength. As the metallocene catalyst, a known or commonly used metallocene catalyst for olefin polymerization can be used. The 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.

  Examples of the polyolefin-based resin include “Wintech WFX6” (metallocene catalyst-based polypropylene) manufactured by Nippon Polypro Co., Ltd., “Zeras # 7000, # 5000” (propylene-α-olefin copolymer) manufactured by Mitsubishi Chemical Corporation, “Kernel” manufactured by Nippon Polyethylene Co., Ltd. is commercially available.

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

  The polyolefin resin preferably has a melting point of 100 to 150 ° C, more preferably 120 to 140 ° C. The melt flow rate (MFR) is preferably from 0.1 to 10 (g / 10 minutes), more preferably from 1 to 5 (g / 10 minutes). If the melting point or MFR is out of the above range, the difference in production conditions with the polyester resin becomes large, making it difficult to form a sheet by co-extrusion and subsequent stretching, resulting in decreased productivity such as film breakage and sufficient orientation. In some cases, the shrinkage may not be improved.

  Content of the said polyolefin-type resin with respect to the total weight of the resin composition which comprises the C layer of this invention is 50 weight% or more, Preferably it is 60-100 weight%, More preferably, it is 65-95 weight%. When the content of the polyolefin-based resin in the C layer is less than 50% by weight, the specific gravity may not be lowered or the shrinkage characteristics may be deteriorated.

  The C layer may contain a tackifier such as petroleum resin or terpene resin in order to improve high shrinkage, lower back strength and prevent spontaneous shrinkage. Examples of the tackifier 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 resin), petroleum resin (aliphatic, aromatic, alicyclic) and the like. Among these, petroleum resin is preferable. A tackifier can be used individually or in combination of 2 or more types. The addition amount in the case of adding a tackifier is preferably 5 to 30% by weight, more preferably 10 to 25% by weight, based on the total weight of the resin composition constituting the C layer. If the amount added exceeds 30% by weight, the shrink film may become brittle. Moreover, if it is less than 5 weight%, the effect of addition may be small. As the tackifier, “Arucon” manufactured by Arakawa Chemical Co., Ltd. can be obtained as a commercial product, and a polyolefin resin containing petroleum resin (for example, “Wintech TX1987FC” manufactured by Nippon Polypro Co., Ltd.): Metallocene catalyst Polypropylene (70% by weight) / polyethylene (5% by weight) / petroleum resin 25% by weight mixed resin) can also be used.

  Among the above, the resin composition (resin composition C) constituting the C layer is, from the viewpoint of imparting shrinkage, a metallocene catalyst-based polypropylene, a metallocene catalyst-based polypropylene (main component), a petroleum resin and / or an olefin-based resin. A mixed resin with an elastomer is particularly preferably exemplified. In addition, as said olefin type elastomer, well-known and usual olefin type elastomers (olefin type thermoplastic elastomer etc.) can be used, but it is not specifically limited, For example, ethylene-propylene copolymer elastomer, ethylene-propylene-diene copolymer elastomer Preferred examples include ethylene-based elastomers such as conjugated diene rubbers such as butadiene rubber and isoprene rubber.

  The C layer of the shrink film of the present invention may contain a recovered raw material as long as the effects of the present invention are not impaired. In this case, the amount of the recovered raw material is about 1 to 30% by weight with respect to the total weight of the resin composition constituting the C layer. Recovered raw materials are non-product parts such as before and after commercialization and film edges, remaining parts when product films are collected from intermediate products, non-standard film waste, polymer waste, and recycled raw materials ( However, it is limited to those resulting from the manufacture of the shrink film of the present invention).

[Shrink film]
As described above, the shrink film of the present invention is formed in the order of A layer (surface layer) / B layer (intermediate layer) / C layer (center layer) / B layer (intermediate layer) / A layer (surface layer) in this order. This is a laminated structure including a laminated structure of three types and five layers in which the C layer is laminated without interposing other layers. Specifically, although not particularly limited, a laminated structure of A / B / C / B / A is preferably exemplified.

  The A / B / C / B / A three-kind five-layer laminated structure is formed by coextrusion. The general method of coextrusion is a method in which the resin compositions A to C are respectively charged into a plurality of extruders each set to a predetermined temperature and coextruded from a T die, a circular die, or the like. At this time, it is preferable to use a manifold or a merging block to form a predetermined laminated 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 types of the resin compositions A to C to be used, and is not particularly limited. However, it is preferable that the molding temperature regions of the resin compositions are close to each other. Specifically, the extrusion temperature of the resin composition A (A layer) is preferably 210 to 240 ° C., the resin composition B (B layer) is 190 to 220 ° C., and the resin composition C (C layer) is 180 to 220. ° C is preferred. Moreover, it is preferable that the temperature of the junction part and die | dye of each resin composition shall be 200-220 degreeC. An unstretched laminated film (sheet) can be obtained by quenching the coextruded polymer using a cooling drum or the like.

  The shrink film of the present invention is a uniaxially or biaxially oriented film from the viewpoint of shrinkage characteristics, and it is necessary that five layers of A / B / C / B / A in the film are oriented. When the five layers of A / B / C / B / A are non-oriented, good shrinkage cannot be obtained. The orientation is not particularly limited, such as uniaxial orientation or biaxial orientation, but substantially uniaxial orientation in the width direction, which is strongly oriented in the film width direction (direction that becomes the circumferential direction when the label is formed into a cylinder) is preferable. Further, it may be a substantially uniaxially oriented film in the longitudinal direction that is strongly oriented in the longitudinal direction (direction perpendicular to the width direction) of the film.

  An oriented film such as the above-described uniaxial orientation and biaxial orientation can be produced by stretching an unstretched laminated film (sheet). Stretching can be selected according to the desired orientation, and may be biaxial stretching in the longitudinal direction (longitudinal direction; MD direction) and width direction (transverse direction; TD direction), or uniaxial stretching in the longitudinal direction or width direction. But you can. The stretching method may be any of a roll method, a tenter method, and a tube method. Stretching conditions vary depending on the types of resin compositions A to C to be used, and are not particularly limited. However, in general, each direction of longitudinal and width is in a range of 70 to 110 ° C. (preferably 80 to 95 ° C.). It is preferable to carry out at a magnification of about 1 to 8 times. For example, after stretching by about 1 to 1.5 times (preferably 1 to 1.3 times) in the longitudinal direction, it is 2 to 8 times (preferably 3 to 8 times, more preferably 4.5 to 8 times) in the width direction. It is preferable to stretch about twice.

  In the shrink film of the present invention, the thickness of the A layer (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 may occur rapidly, and if it is less than 3 μm, the shrinkage may be insufficient.

  In the shrink film of the present invention, the thickness of the B layer (one layer) is not particularly limited, but is preferably 3 to 15 μm, more preferably 5 to 10 μm. When the thickness of the B layer exceeds 15 μm, the shrinkage may be nonuniform, and when it is less than 3 μm, it may be difficult to form the layer.

  In the shrink film of the present invention, the thickness of the C layer (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 shrinkage rate may decrease, and if it is less than 10 μm, the shrinkage may occur rapidly.

  In the shrink film of the present invention, when the total thickness is 100%, the thickness ratio of the A layer (total of two layers) and the B layer (total of two layers) is preferably 2 to 50%. Further, the thickness ratio of the C layer is preferably 40 to 95%.

  Although the thickness of the shrink film of this invention is not specifically limited, 20-100 micrometers is preferable, More preferably, it is 20-80 micrometers, More preferably, it is 20-50 micrometers.

  In the shrink film of the present invention, since the surface layer (A layer) is mainly composed of a polyester resin, it has high shrinkage and can impart printability, wear resistance, and chemical resistance to the surface. . Since the central layer (C layer) is mainly composed of a polyolefin resin, the shrink label has a low specific gravity, and in addition, the shrinkage behavior can be moderated by suppressing rapid shrinkage of the label. The intermediate layer (B layer) has high adhesion to both the A layer and the C layer, and plays a role of improving interlayer strength. By laminating these layers with the above-described laminated structure, a shrink film (or a shrink label using the same) having a low shrinkage and a high shrinkage and having a high interlayer strength even after shrink processing is obtained. be able to.

In particular, the present invention is characterized in that a styrene-based thermoplastic elastomer is used for the intermediate layer (B layer). Styrenic thermoplastic elastomers have stickiness due to polarity (such as hydrogen bonding) and stick to other layers when compared to olefin-modified products such as maleic anhydride-modified and epoxy-modified polyolefin resins. In common, styrene-based thermoplastic elastomers that contain a large amount of rubber components have a flexible main chain and are stretchable, which makes it easier for the B layer to follow deformation during stretching, losing tackiness and adhesion. It is excellent in that it is difficult to do. On the other hand, when an olefin-based modified body having a relatively rigid main chain is used as the B layer, particularly when stretching at a high magnification, the B layer cannot follow the stretching deformation, and the interaction due to the polarity is easily lost ( For example, the hydrogen bond is likely to be broken), and thus the adhesive force is likely to be reduced during stretching. As described above, in the present invention, since the interlayer strength is high and the interlayer strength is not easily lowered by the stretching treatment, the interlayer strength when used as a shrink film (particularly a high shrink type shrink film) is particularly excellent. be able to.
Furthermore, in addition to being able to stretch at a high magnification as described above, the shrinkability of the shrink label of the shrink label can be further improved because the shrinkability of the styrene thermoplastic elastomer of the B layer is good.

[Shrink label]
By using the shrink film of the present invention as a base material and providing a printing layer on at least one side thereof, it can be preferably used as a shrink label. In addition to the printed layer, the shrink label may be provided with a protective layer, an anchor coat layer, a primer coat layer, a resin layer such as an adhesive layer (pressure sensitive, heat sensitive, etc.), a coating layer, Furthermore, you may provide layers, such as a nonwoven fabric and paper. As a specific configuration of the shrink label of the present invention, for example, a layer configuration such as printing layer / A / B / C / B / A, printing layer / A / B / C / B / A / printing layer is preferably exemplified. The In addition, the shrink film of this invention can also be used for shrink label use by itself, even when a printing layer is not provided.

  The shrink label of the present invention has a printed layer (for example, a layer displaying a product name, an illustration, handling precautions, etc.) on at least one surface. The printing layer is formed by applying printing ink. From the viewpoint of productivity, workability, and the like, the coating method is preferably provided by an off-line coating in which coating is performed using a known printing method after film formation. As a printing method, a conventional method can be used, but gravure printing or flexographic printing is most preferable. The printing ink used for forming the printing layer is made of, for example, a pigment, a binder resin, a solvent, and other additives. Although it does not specifically limit as said binder resin, For example, resin, such as an acrylic type, a urethane type, a polyamide type, a vinyl chloride-vinyl acetate copolymer type, a cellulose type, a nitrocellulose type, can be used individually or in combination. As the pigment, 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 in accordance with 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. Examples of the solvent include organic solvents such as toluene, xylene, methyl ethyl ketone, ethyl acetate, methyl alcohol, ethyl alcohol, and isopropyl alcohol, and commonly used solvents such as water.

Although the said printing layer is not specifically limited, Active energy ray-curable resin layers, such as visible light, an ultraviolet-ray, and an electron beam, may be sufficient. This is effective for preventing deformation of the film due to excessive heat. For example, in the case of curing by ultraviolet rays, an ultraviolet (UV) lamp, such as using an ultraviolet LED or an ultraviolet laser, ultraviolet ray having a wavelength 300～460Nm (or near UV), irradiation intensity 150~1000mJ / cm ^2, irradiation time 0.1 It can be performed under about 3 seconds. In the case of an active energy ray-curable printing layer, it is preferable to add a photopolymerization initiator such as a photoradical polymerization initiator and a photocationic polymerization initiator to the printing ink in addition to the above. Examples of the photo radical polymerization initiator include benzophenone, thioxanthone, acetophenone, and acylphosphine polymerization initiators. Examples of the photo cationic polymerization initiator include diazonium salts, diaryl iodonium salts, and triaryls. Examples include sulfonium salts, silanol / aluminum complexes, sulfonate esters, and imide sulfonates. Although content of these photoinitiators is not specifically limited, 0.5-7 weight% is preferable with respect to the whole printing ink, More preferably, it is 1-5 weight%. Furthermore, you may add a sensitizer to printing ink as needed from a viewpoint of improving production efficiency. In this case, the sensitizer is, for example, an amine-based sensitizer such as an aliphatic, aromatic amine, piperidine, or other amine containing a nitrogen in the ring; an allyl-based or o-tolylthiourea-based urea-based sensitizer; sodium diethyl Sulfur compound sensitizers such as dithiophosphate; Anthracene sensitizers; Nitrile sensitizers such as N, N-disubstituted p-aminobenzonitrile compounds; Phosphorus compound systems such as tri-n-butylphosphine Sensitizers; nitrogen compound sensitizers such as N-nitrosohydroxylamine derivatives and oxazolidine compounds; chlorine compound sensitizers such as carbon tetrachloride. Although it does not specifically limit as content of a sensitizer, 0.1 to 5 weight% is preferable with respect to the whole printing ink, Most preferably, it is 0.3 to 3 weight%.

  Although the thickness of the said printing layer is not specifically limited, For example, it is about 0.1-10 micrometers. 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 it may become difficult to follow the shrinkage | contraction of a film at the time of shrink processing.

[Physical properties of shrink film]
The shrink film of the present invention has excellent interlayer strength (interlaminar peel strength). The interlayer strength (the interlayer strength of the shrink film after stretching orientation) is preferably 2 (N / 15 mm) or more, more preferably 3 (N / 15 mm) or more. When the interlaminar strength is less than 2 (N / 15 mm), the film layers may be peeled off after processing or commercialization, resulting in reduced productivity and quality problems. In addition, the said interlayer intensity | strength says the intensity | strength of the interlayer with the lowest interlayer intensity | strength in a shrink film in a T-type peeling test (based on JISK6854-3, peeling rate: 200 mm / min). Usually, the interlayer strength between the A layer and the B layer is the lowest.

  The shrinkage rate in the main orientation direction (mainly in the direction subjected to the stretching treatment) at 90 ° C. for 10 seconds (warm water treatment) of the shrink film (before shrink processing) of the present invention is preferably 35% or more, more preferably 35 to 35%. 80%, more preferably 55-80%. When the heat shrinkage rate is less than the above range, in the process of closely attaching the label to the container with heat, the shrinkage is not sufficient, so that it becomes difficult to follow the shape of the container, and the finish is particularly poor for a container having a complicated shape. Sometimes.

  In addition, as for the thermal contraction rate of the direction orthogonal to the said main orientation direction in 90 degreeC 10 second (warm water process) of the shrink film (before shrink process) of this invention, -5-10% is preferable. The thermal shrinkage rate in the direction orthogonal to the main orientation direction at 100 ° C. for 10 seconds (warm water treatment) is preferably −5 to 15%.

  The transparency (transparency) (haze value: JIS K 7105, converted to 40 μm thickness) (unit:%) of the shrink film (A / B / C / B / A3 type five-layer laminated film) of the present invention is preferably less than 10. More preferably, it is less than 5.0, More preferably, it is less than 2.0. When the haze value is 10 or more, the inside of the shrink film (the side that becomes the container side when the label is attached to the container) is printed, and in the case of a shrink label that shows printing through the film, Printing may be cloudy and decorative properties may be reduced. However, even if the haze is 10 or more, it can be sufficiently used in applications other than the above-mentioned applications that show printing through a film.

[processing]
The shrink label of the present invention is, for example, a cylindrical label of a type in which both ends of the label are sealed with a solvent or an adhesive and attached to the container, or one end of the label is attached to the container and the label is wound The other end can be suitably used as a winding-type label that overlaps with one end to form a cylinder. The center seal strength of this cylindrical label is preferably 2 N / 15 mm or more. When the seal strength is less than 2N / 15 mm, the seal portion may be peeled off after processing or product production, which may reduce the productivity or cause the label to drop off.

  Although the manufacturing method of the said cylindrical label is not specifically limited, For example, it is as follows. The shrink label of the present invention is printed on a shrink film stretched in the long width direction, then slit to a predetermined width, wound into a roll shape, and a roll shape in which a plurality of labels are continuous in the long direction. After being made into a product, it is used for processing. While feeding one of these rolls, the film is formed into a cylindrical shape so that the main stretching direction (for example, the width direction) of the film is in the circumferential direction. Specifically, a long shrink label is formed in a cylindrical shape, and is about 2 to 4 mm wide in the longitudinal direction on one side edge of the label, 1,3-dioxolane, tetrahydrofuran (THF), etc. The solvent or adhesive (hereinafter referred to as solvent) is applied to the inner surface, rounded into a cylindrical shape, and the solvent-coated portion is overlapped at a position of 5 to 10 mm from the other side edge, and the other side edge Adhering to the outer surface (center seal), a continuous cylindrical label continuous body (long cylindrical shrink label) is obtained. In the case where a perforation for label excision is provided, a perforation having a predetermined length and pitch is formed in the longitudinal 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 shrink label of the present invention is attached to a container and used as a labeled container. Such containers include, for example, soft drink bottles such as PET bottles, milk bottles for home delivery, food containers such as seasonings, alcohol beverage bottles, pharmaceutical containers, chemical containers such as detergents, sprays, cups, etc. This includes noodle containers. The shape of the container includes various shapes such as a cylindrical shape, a square bottle, and a cup type. Further, the material of the container includes plastic such as PET, glass, metal and the like.

  The above-mentioned container with a label can be produced by cutting a long cylindrical shrink label, mounting it on a predetermined container, shrinking the label by heat treatment, and closely contacting the container. Specifically, the above-described long cylindrical shrink label in a roll shape is supplied to an automatic label mounting device (shrink labeler), cut into a required length, and formed into a cylindrical shrink label. A shrink label is externally fitted to a container filled with the contents, and is passed through a hot air tunnel or steam tunnel at a predetermined temperature, or is heat-shrinked by radiant heat such as infrared rays, and is brought into close contact with the container to obtain a labeled container. . Examples of the heat treatment include treatment with steam at 80 to 100 ° C. (passing through a heating tunnel filled with steam and steam).

[Methods for measuring physical properties and methods for evaluating effects]
(1) Interlaminar strength (T-type peeling)
The interlayer strength was measured for the unstretched film (before stretching) and the shrink film (after stretching) prepared in the examples and comparative examples, and the shrink film was evaluated.
Strip-shaped sample (200 mm (unstretched film or shrink film width direction) × 15 mm (width direction of the unstretched film or shrink film)) with a width of 15 mm in the longitudinal direction (unstretched film or shrink film forming direction) and long in the width direction (perpendicular to the longitudinal direction) Unstretched film or shrink film longitudinal direction)) was collected. Hereinafter, the sample width direction refers to the longitudinal direction of an unstretched film or a shrink film.
Using the long side direction of the sample (width direction of the unstretched film or shrink film) as the measurement direction, a T-type peel test (based on JIS K 6854-3) was performed under the following conditions to measure the peel load between the layers.
The average value of the peeling load was defined as the interlayer strength (N / 15 mm). When the interlayer strength of the shrink film was 2 (N / 15 mm) or more, the interlayer strength was good (◯), and when it was less than 2 (N / 15 mm), the interlayer strength was judged as poor (x).
(Measurement condition)
Measuring device: Autograph manufactured by Shimadzu Corporation (AG-IS: load cell type 500N)
Temperature and humidity: Temperature 23 ± 2 ° C, humidity 50 ± 5% RH (JIS K 7000 standard temperature state 2nd grade)
Initial chuck interval: 40 mm
Sample width: 15mm
Number of tests: 3 times Tensile speed: 200 mm / min Stroke: 150 mm (If it broke, it was interrupted and data up to that point was obtained.)
First half deletion range: 50mm
Sensitivity: 1
In addition, the said interlayer strength shall be evaluated about the interlayer with the weakest interlayer strength in a laminated structure, and it evaluated by the interlayer strength of A layer and B layer in an Example and a comparative example.

(2) Thermal shrinkage (90 ° C for 10 seconds)
The measurement of heat shrinkage (90 ° C., 10 seconds) will be described as an example.
From the shrink film (before shrink processing) obtained in the examples and comparative examples, the measurement direction (main orientation direction: longitudinal direction or width direction of the base film) is 120 mm in length (mark interval 100 mm), and the width of the sample is 5 mm. A rectangular sample piece is prepared.
The sample piece is heat-treated in warm water at 90 ° C. for 10 seconds (under no load), the difference between the marked lines before and after the heat treatment is read, and the thermal contraction rate is calculated by the following formula.
Shrinkage rate (%) = (L ₀ −L ₁ ) / L ₀ × 100
L ₀ : Size of sample before heat treatment (main orientation direction: longitudinal direction or width direction)
L ₁ : Sample dimensions after heat treatment (same direction as L ₀ )
The shrinkage characteristics were evaluated based on the following criteria from the heat shrinkage rate (shrinkage rate) in the main orientation direction. In the examples, the main orientation direction was the width direction of the shrink film.
55% or more: ◎ (excellent shrinkage properties)
45% or more and less than 55%: ○ (good shrinkage characteristics)
35% or more and less than 45%: △ (usable level)
Less than 35%: × (defective shrinkage characteristics)

(3) Transparency (haze value)
Using the shrink film (thickness 40 μm) obtained in Examples and Comparative Examples, measurement was performed according to JIS K 7105. In the case of films having different thicknesses, the thickness may be converted to 40 μm.
From the haze value (unit:%), the following criteria were used for evaluation.
Less than 2.0: ◎ (excellent transparency)
2.0 or more and less than 10: ○ (good transparency)
10 or more: × (poor transparency)

  EXAMPLES Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Tables 1 and 2 show the composition and physical properties of the resin composition of each layer used for producing the shrink film in Examples and the evaluation results of the obtained shrink film and shrink label. In addition, the unit of the compounding quantity in a table | surface is a weight part in each resin composition. Table 3 shows the copolymer composition of the styrene copolymers (Tables 1 and 2) used in Examples and Comparative Examples.

Example 1
As shown in Table 1, 100 parts by weight of NPG-modified amorphous polyester resin (“Belpet E-02” manufactured by Bell Polyester Products Co., Ltd.) was used as the resin composition A constituting the A layer. Further, 100 parts by weight of a hydrogenated styrene thermoplastic elastomer (“Tuftec H1041” manufactured by Asahi Kasei Chemicals Corporation) was used as the resin composition B constituting the B layer. Further, as the resin composition C constituting the C layer, 70 parts by weight of a metallocene catalyst-based polypropylene resin (“Wintech WFX6” manufactured by Nippon Polypro Co., Ltd.) and an olefin-based elastomer resin (“Zeras 7023” manufactured by Mitsubishi Chemical Corporation) ) 30 parts by weight of mixed resin was used.
The resin composition A was charged in the extruder a heated to 220 ° C., the resin composition B in the extruder b heated to 200 ° C., and the resin composition C in the extruder c heated to 200 ° C. Melt extrusion was performed using the above three extruders. The resin extruded from the extruder c is the center layer, the resin extruded from the extruder b is on both sides of the center layer, and the resin extruded from the extruder a is further merged by using a merge block. After being extruded from a T-die (slit spacing 1 mm), it was rapidly cooled on a casting drum cooled to 25 ° C. to obtain a three-kind five-layer laminated unstretched film (thickness: 200 μm). The lamination thickness ratio of the unstretched film was surface layer / intermediate layer / center layer / intermediate layer / surface layer (A / B / C / B / A) = 1/1/3/1/1.
Next, the biaxially stretched film which mainly shrink | contracts in a uniaxial direction was obtained by extending the unstretched film which adjusted thickness 5 times at 90 degreeC in the width direction. By adjusting the film forming speed, a shrink film having a total thickness of 40 μm (layer thickness ratio: 1/1/3/1/1) was obtained.
Moreover, Dainippon Ink Industries Co., Ltd. "fine wrap NTV" was gravure-printed on the obtained shrink film, the printing layer was formed in thickness of 2 micrometers, and the shrink label was obtained.
As shown in Table 1, the obtained shrink film had good interlayer strength before and after stretching. Furthermore, it was highly shrinkable and excellent in transparency (transparency).

Examples 2-20
As shown in Tables 1 and 2, a shrink film and a shrink label were obtained in the same manner as in Example 1 by changing the resin type and resin composition used for the resin compositions A to C of each layer.
As shown in Tables 1 and 2, the obtained shrink film had good interlayer strength, heat shrinkage characteristics, and transparency.

Comparative Examples 1-3
As shown in Table 2, a shrink film and a shrink label were obtained in the same manner as in Example 1 except that the resin type used for the resin composition B was changed.
The resulting shrink film and shrink label had low interlayer strength after stretching.

Claims (5)

Configured surface layer mainly of amorphous polyester resin (A layer), styrene monomer and 10 to 45% by weight and a conjugated diene 55 90 wt% including styrene heat as a monomer component Propylene obtained by polymerization using a polypropylene and a metallocene catalyst obtained by polymerization using an intermediate layer (B layer) composed mainly of a plastic elastomer and / or a derivative thereof, and a metallocene catalyst A central layer (C layer) composed mainly of a polyolefin resin selected from the group consisting of α-olefin random copolymers is in the order of A layer / B layer / C layer / B layer / A layer. Laminated without going through the layers
The amorphous polyester-based resin is polyethylene terephthalate using terephthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component, wherein the dicarboxylic acid component and / or a part of the diol component is another dicarboxylic acid component and / or Or a modified polyethylene terephthalate substituted with a diol component ,
A shrink film, wherein the thickness of the C layer is 40 to 95% with respect to 100% of the total thickness of the shrink film. The shrink film according to claim 1, wherein in the styrene thermoplastic elastomer constituting the B layer, the styrene monomer is styrene and the conjugated diene is 1,3-butadiene and / or isoprene. The shrink film according to claim 1, wherein the C layer further contains a tackifier and / or an olefin-based elastomer. The B layer further contains a tackifier, and the addition amount of the tackifier in the B layer is 5 to 30% by weight based on the total weight of the resin composition constituting the B layer. The shrink film as described in any one of the items. The shrink label which provided the printing layer in the at least one surface side of the shrink film in any one of Claims 1-4.