JP4717597B2 - Heat-shrinkable laminated film, molded product using the film, heat-shrinkable label, and container - Google Patents

Description

The present invention relates to a heat-shrinkable laminated film, and a molded article and container using the film. More specifically, the shrinkable finish, film stiffness, and transparency at the time of regeneration addition are good, and the film naturally shrinks. , Heat-shrinkable laminated film suitable for uses such as shrink wrapping, shrink-bound wrapping and shrink labels, in which delamination and shrinkage stress are suppressed, and a molded product using the film,
Concerning the container.

  Currently, soft drinks such as juice are sold in a state of being filled in a container such as a bottle or a plastic bottle. At that time, in order to differentiate from other products and improve the visibility of the products, a heat-shrinkable label printed on the outside of the container is attached. In recent years, the demand has been increasing more and more, and a highly shrink-finished appearance can be obtained in a relatively short time and at a low temperature, and a natural shrinkage (a little higher than normal temperature, for example, in summer, the film is a little before its original use). There is a demand for a heat-shrinkable label with a small shrinkage). At present, polystyrene, polyester, polyvinyl chloride, polyolefin and the like are generally used as the material of the heat-shrinkable label.

  Among the above materials, the polyvinyl chloride heat-shrinkable film is inferior in heat resistance and has a problem of generating harmful gases such as hydrogen chloride at the time of incineration after use. On the other hand, a polystyrene heat-shrinkable film mainly composed of a styrene-butadiene copolymer has been proposed and used, but this polystyrene-based heat-shrinkable film is compared with a polyvinyl chloride heat-shrinkable film. On the other hand, the shrink finish is good, but the natural shrinkage is large and the film waist (rigidity at room temperature) is low, so that there is a problem such as poor mounting due to label folding in the label mounting process.

  Polyester heat-shrinkable film, on the other hand, has low natural shrinkage and high film elasticity, but it has good shrinkage finish compared to polyvinyl chloride heat-shrinkable film. There was a problem that shrinkage spots and wrinkles are likely to occur due to the contraction). In recent years, as the thickness of PET bottles has been reduced, polyester heat-shrinkable films have high stress during heat shrinkage. For example, if PET bottles are covered with contents, the bottles are deformed and the temperature is reduced. Hot beverage PET bottles containing beverages have various problems such as the contents being blown out by the shrinkage stress of the film when the cap is opened.

  In order to solve the above-mentioned problem, by using a resin obtained by mixing a predetermined amount of a modified polybutylene terephthalate resin copolymerized with a predetermined amount of an aromatic dicarboxylic acid other than terephthalic acid, a shrinkage finish property Has been proposed (Patent Document 1). Furthermore, among the polyhydric alcohol components, there is also a method for improving the shrink finish by using a copolymer polyester resin in which 1,4-cyclohexanedimethanol, 1,4-butanediol, or polytetramethylene ether glycol is modified. It has been proposed (Patent Document 2). However, the shrink finish of these heat-shrinkable films has not yet reached that of styrenic heat-shrinkable films, and the shrinkage stress has not been sufficiently reduced.

  Further, as another means for solving the above problem, a base in which front and back layers made of a polyester resin containing 1,4-cyclohexanedimethanol as a diol component are laminated on both sides of an intermediate layer made of polystyrene resin. A shrink label provided with a film has been reported (see Patent Document 3). Since this shrink film is laminated with a polystyrene resin having a good shrink finish, the shrink finish is better than that of the film made only of a polyester resin. However, the interlayer adhesion between the polystyrene-based resin and the polyester-based resin is insufficient, and there has been a problem that delamination is likely to occur during printing during the secondary processing.

On the other hand, as a technique for improving the interlayer adhesion, a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene derivative is used for the inner layer, a copolymer polyester system is used for both outer layers, and an ethylene-vinyl acetate copolymer is used for the adhesive layer. In addition, a film using an ethylene-unsaturated carboxylic acid copolymer has been reported (see Patent Document 4). However, this film is incompatible with the vinyl aromatic hydrocarbon and conjugated diene derivative in the inner layer and the ethylene-vinyl acetate copolymer in the adhesive layer. When added (hereinafter referred to as “regeneration addition”), there is a problem that the transparency of the entire film tends to be lowered.
JP 2003-12833 A JP 2002-212405 A JP 2002-351332 A Japanese Patent Publication No. 5-33896

  The present invention has been made in view of the above problems, and the object of the present invention is good shrinkage finish, film stiffness, and transparency at the time of addition of regeneration, natural shrinkage of the film, delamination, Another object of the present invention is to provide a heat-shrinkable laminated film suitable for applications such as shrink wrapping, shrink-bound wrapping and shrinkage labels, in which shrinkage stress is suppressed.

  Another object of the present invention is to provide a molded product and a container using the film suitable for applications such as shrink wrap, shrink bundle wrap and shrink labels.

As a result of intensive studies on the composition, layer structure, and molding process conditions of the surface layer, adhesive layer, and intermediate layer forming the film, the present inventors have succeeded in obtaining a film that can solve the above-described problems of the prior art. The present invention has been completed.
That is, the object of the present invention is achieved by the following heat-shrinkable laminated film.
(1) A laminated film having a surface layer (S layer), an intermediate layer (M layer) and an adhesive layer (AD layer), each layer comprising a resin composition containing the following components as main components, The tensile elastic modulus measured according to JIS K7127 in the direction orthogonal to the shrinkage direction is 1200 MPa or more, and the maximum shrinkage stress in the film main shrinkage direction when immersed in silicon oil at 90 ° C. for 10 seconds is 5 MPa or more and 8 MPa or less. A heat-shrinkable laminated film characterized by being.
Surface layer (S layer): with a polyvalent carboxylic acid residue and an aromatic polyester resin composition intermediate layer containing a polyhydric alcohol residue (M layer): a styrene series hydrocarbon and a conjugated diene hydrocarbon Styrenic resin composition adhesive layer (AD layer) comprising a copolymer: including a copolymer of styrene hydrocarbon and conjugated diene hydrocarbon or a hydrogenated derivative thereof, and the total of the polymer or hydrogenated derivative Resin composition having a styrene-based hydrocarbon content of 5% by mass or more and 40% by mass or less (2) It has a surface layer (S layer), an intermediate layer (M layer), and an adhesive layer (AD layer). A laminated film composed of a resin composition having the following components as main components and stretched at least 60 times to 120 ° C. in a uniaxial direction at least 2 times to 7 times, wherein the main shrinkage direction of the film J in the orthogonal direction Heat having a tensile elastic modulus measured in accordance with IS K7127 of 1200 MPa or more and a maximum shrinkage stress in the film main shrinkage direction when immersed in 90 ° C. silicon oil for 10 seconds is 5 MPa or more and 8 MPa or less. Shrinkable laminated film.
Surface layer (S layer): polyvalent carboxylic acid residue and an aromatic polyester resin composition intermediate layer containing a polyhydric alcohol residue (M layer): a block of a styrene series hydrocarbon and a conjugated diene hydrocarbon Styrenic resin composition adhesive layer (AD layer) comprising a copolymer: consisting of a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon or a hydrogenated derivative thereof, in the copolymer or hydrogenated derivative Resin composition having a styrene-based hydrocarbon content of 5% by mass or more and 40% by mass or less (3) With respect to 100 parts by mass of the resin in which the intermediate layer (M layer) constitutes the intermediate layer (M layer), The heat-shrinkable laminated film according to the above (1) or (2), comprising 1 part by mass or more and 100 parts by mass or less of the resin constituting the surface layer (S layer).
(4) The said intermediate | middle layer (M layer) contains 1 mass part or more and 30 mass parts or less of resin which comprises the said contact bonding layer (AD layer) with respect to 100 mass parts of resin which comprises this intermediate | middle layer (M layer). The heat-shrinkable laminated film according to any one of (1) to (3).
(5) The aromatic polyester-based resin composition constituting the surface layer (S layer) is composed of an aromatic dicarboxylic acid residue and a diol residue, and is 15 mol% or more and 50 mol% or less in all diol residues. The heat-shrinkable laminated film according to any one of the above (1) to (4), which is a resin composition mainly comprising an amorphous polyethylene terephthalate-based resin containing a 1,4-cyclohexanedimethanol residue.
( 6 ) The heat-shrinkable laminated film according to any one of the above (1) to ( 5 ), wherein the glass transition point of the copolymer constituting the adhesive layer (AD layer) or a hydrogenated derivative thereof is 20 ° C. or lower. .
( 7 ) The heat-shrinkable laminated film according to any one of (1) to (6), wherein a thickness ratio of the surface layer (S layer) to the thickness of the entire film is 10% to 70%.
( 8 ) The heat-shrinkable laminated film according to any one of (1) to ( 7 ), wherein the haze value measured in accordance with JIS K7105 is 10% or less.
( 9 ) The thermal contraction rate in the main contraction direction when immersed in warm water at 70 ° C. for 10 seconds is 10% or more and 40% or less, and the thermal contraction rate in the main contraction direction when immersed in warm water at 80 ° C. for 10 seconds is 30. heat-shrinkable laminated film according to any one of% or more is 70% or less (1) to (8).

Another object of the present invention is achieved by the following molded article, heat-shrinkable label, and container.
(10) (1) to (9) molded article using the heat-shrinkable laminate film according as the substrate in either.
(11) (1) to heat-shrinkable label using as a substrate a heat-shrinkable laminate film according to any one of (9).
( 12 ) A container equipped with the molded product according to (10) or the heat-shrinkable label according to ( 11 ).

  According to the present invention, shrink finish packaging, shrinkage of the film having good shrinkage finish, film stiffness, and transparency at the time of regenerative addition, and suppressing natural shrinkage, delamination, and shrinkage stress of the film. A heat-shrinkable laminated film suitable for uses such as bundling packaging and shrinkage labels can be provided.

  Further, according to the present invention, the shrinkage packaging and shrinkage of the film having the firmness of the film, excellent in shrink finish and transparency at the time of regeneration addition, and suppressing the natural shrinkage, delamination and shrinkage stress of the film. It is possible to provide a molded article and a heat-shrinkable label that are suitable for applications such as bundling packaging and shrinkage labels. Furthermore, according to the present invention, it can be fixed in a desired position regardless of the shape of the attachment, and there are no abnormalities such as wrinkles, occurrence of avatars, insufficient shrinkage, etc., and it has a transparent and beautiful appearance. A container equipped with a molded article or a heat-shrinkable label can be provided.

Hereinafter, the heat-shrinkable laminated film, molded product, heat-shrinkable label and container of the invention will be described in detail.
In the present specification, “having as a main component” is intended to allow other components to be included within a range that does not interfere with the action and effect of the resin constituting each layer. Although this term does not restrict | limit a specific content rate, it is a component which occupies 50 mass% or more of the whole component of each layer, Preferably it is 70 mass% or more, More preferably, it is 80 mass% or more. In addition, the “main shrinkage direction” means a direction in which the thermal shrinkage rate is large between the longitudinal direction (longitudinal direction) of the film and the lateral direction (width direction) of the film. The direction corresponding to the direction is meant, and the “orthogonal direction” means a direction perpendicular to the main contraction direction.

[Heat-shrinkable laminated film]
The heat-shrinkable laminated film of the present invention (hereinafter also referred to as “the film of the present invention”) is composed of a surface layer (S layer) mainly composed of a polyester resin composition and an intermediate layer (M layer) composed of a styrene resin. And an adhesive layer (AD layer) for improving interlayer adhesion between the surface layer (S layer) and the intermediate layer (M layer).

  It is important that the film of the present invention has a tensile modulus measured in accordance with JIS K7127 in a direction orthogonal to the film main shrinkage direction is 1200 MPa or more, preferably 1300 MPa or more, more preferably 1400 MPa or more. The upper limit of the tensile modulus is not particularly limited, but is preferably about 2500 MPa to 3000 MPa in a commonly used heat-shrinkable film. If the tensile modulus of elasticity in the direction perpendicular to the main shrinkage direction of the film is 1200 MPa or more, the film as a whole has high waist (rigidity at room temperature), and even when the film thickness is reduced, it is suitable for containers such as PET bottles. When covering the bag-formed film with a labeling machine or the like, it is possible to suppress the occurrence of problems such as covering the film obliquely or the yield is likely to decrease due to the film being folded back. The said tensile elasticity modulus can be measured on the conditions of 23 degreeC based on JISK71127.

  The film of the present invention has a maximum shrinkage stress in the film main shrinkage direction of 5 MPa or more when immersed in 90 ° C. silicon oil for 10 seconds, and the upper limit is 8 MPa or less, preferably 7.5 MPa or less, more preferably 7 MPa or less. This is very important. When the maximum shrinkage stress is 5 MPa or more, for example, when the label is heated and shrunk and attached to the bottle, the label and the bottle are completely adhered to each other, and a good finished appearance is obtained. This is an undesirable phenomenon because, for example, a label printed pattern that should originally be located on the square bottle panel surface comes to the bottle edge, and this is an undesirable phenomenon. In recent years, the thickness of the film has been reduced, and when filling the contents of PET bottles having various shapes, the bottle may swell due to internal pressure, and the appearance may deteriorate. Even for such a phenomenon, it is preferable that the maximum shrinkage stress is 5 MPa or more because there is an effect of sufficiently correcting the swelling of the bottle with the stress of the film. On the other hand, when the maximum shrinkage stress is 8 MPa or less, when the label is attached with the steam shrinker, it is difficult to generate a site where the shrinkage behavior of the film is different from the temperature spot in the shrinker, and spots, wrinkles, avatars, etc. Since it does not occur easily, the shrink finish is good. Moreover, since the jumping out of the content at the time of using as a shrink label for hot drink PET bottles can be suppressed, it is preferable.

  In the film of the present invention, the tensile modulus of elasticity and the maximum shrinkage stress in the direction of main film shrinkage are the composition of the polyester resin composition of the surface layer (S layer), the thickness ratio of the surface layer (S layer) to the total film, and stretching. It can be adjusted to the above range by appropriately adjusting the stretching temperature and stretching ratio at the time. This point will be described later.

Next, each layer forming the film of the present invention will be described in detail.
<Surface layer (S layer)>
The surface layer (S layer) of the film of the present invention is composed of a polyester-based resin composition containing as a main component at least one thermoplastic polyester resin containing a polyvalent carboxylic acid residue and a polyhydric alcohol residue. Yes.

  Examples of the polyvalent carboxylic acid residue used in the surface layer (S layer) include terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2,5-dichloroterephthalic acid, 2-methylterephthalic acid, 4,4- Stilbene dicarboxylic acid, 4,4-biphenyl dicarboxylic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, bisbenzoic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4, Aromatic dicarboxylic acid residues derived from 4-diphenyl ether dicarboxylic acid, 4,4-diphenoxyethanedicarboxylic acid, 5-Na sulfoisophthalic acid, ethylene-bis-p-benzoic acid, adipic acid, sebacic acid, Azelaic acid, dodecanedioic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-si Aliphatic dicarboxylic acid residues derived from the B-hexane dicarboxylic acid and the like. These polyvalent carboxylic acid residues may be composed of one kind of residue alone or two or more kinds of residues.

  Examples of the polyhydric alcohol residue used in the surface layer (S layer) include diethylene glycol, ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3- Propanediol, trans-tetramethyl-1,3-cyclobutanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol 1,6-hexanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, decamethylene glycol, cyclohexanediol, p-xylenediol, bisphenol A, tetrabromobisphenol A, tetrabromobisphenol A-bis (2-hydroxye Such residues derived from ether) and the like. These polyhydric alcohol residues may be composed of one kind of residue alone or two or more kinds of residues.

When the thermoplastic polyester resin is composed of two or more types of residues, the most frequently contained residue is the main residue, that is, the one having the largest mass (mol%) is defined as the first residue. A component having a smaller amount than the residue will be described below as a component of the second residue or less (that is, the second residue, the third residue,...).
In the present invention, preferred polyhydric alcohol residue mixtures include, for example, ethylene glycol as the first residue, 1,4-butanediol, neopentyl glycol, diethylene glycol, polytetramethylene glycol, and 1 as the second residue. , 4-cyclohexanedimethanol, and at least one selected from the group consisting of 1,4-cyclohexanedimethanol, preferably 1,4-cyclohexanedimethanol.

  Further, the preferred mixture of polyvalent carboxylic acid residues is, for example, selected from the group consisting of terephthalic acid as the first residue and isophthalic acid, 1,4-cyclohexanedicarboxylic acid, succinic acid and adipic acid as the second residue. Or a mixture of residues derived from isophthalic acid.

  The total content of polyvalent carboxylic acid residues and polyhydric alcohol residues below the second residue is the total amount of polyvalent carboxylic acid residues (100 mol%) and the total amount of polyhydric alcohol residues (100 mol). %) Is 10 mol% or more, preferably 15 mol% or more, and 50 mol% or less, preferably 45 mol% or less. If the content of the residues of 2 residues or less is 10 mol% or more, the degree of crystallinity of the resulting polyester can be adjusted low. On the other hand, when the content of the component having 2 residues or less is 50 mol% or less, the advantages of the first residue can be utilized.

  For example, when the polyvalent carboxylic acid residue is a terephthalic acid residue, the first residue of the polyhydric alcohol residue is an ethylene glycol residue, and the second residue is a 1,4-cyclohexanedimethanol residue, The content of the 1,4-cyclohexanedimethanol residue as the second residue is the total amount of terephthalic acid as the dicarboxylic acid component (100 mol%) and the total amount of ethylene glycol and 1,4-cyclohexanedimethanol (100 In the range of 10 mol% or more, preferably 15 mol% or more, and 50 mol% or less, preferably 45 mol% or less, more preferably 40 mol% or less. It is desirable to be. By using an ethylene glycol residue and a 1,4-cyclohexanedimethanol residue as the diol residue within this range, the crystallinity of the obtained polyester can be adjusted to be low and the fracture resistance can be improved.

  Furthermore, in the above example, when the polyvalent carboxylic acid residue is composed of a terephthalic acid residue as the first residue and an isophthalic acid residue as the second residue, The content of alcohol residues with 1,4-cyclohexanedimethanol residues is the total amount of terephthalic acid residues and isophthalic acid residues (100 mol%), ethylene glycol residues and 1,4-cyclohexanedimethanol residues. 10% or more, preferably 15 mol% or more, more preferably 25 mol% or more, and 40 mol% or less, preferably 38%, based on the total (200 mol%) of the total amount of groups (100 mol%) It is desirable that it is in the range of not more than mol, more preferably not more than 35 mol%.

  Specific examples of the thermoplastic polyester resin composed of the polyvalent carboxylic acid residue and the polyhydric alcohol residue include, for example, polyethylene terephthalate resin, polypropylene terephthalate resin, polybutylene terephthalate resin, polyethylene isophthalate resin, polyethylene naphthalate. Examples thereof include a phthalate resin, a polybutylene naphthalate resin, a polyethylene terephthalate-isophthalate copolymer resin, and an amorphous polyethylene terephthalate resin containing a 1,4-cyclohexanedimethanol component in all polyhydric alcohol residues. Among these, an amorphous polyethylene terephthalate resin in which the polyvalent carboxylic acid component is terephthalic acid and the polyhydric alcohol component is ethylene glycol and 1,4-cyclohexanedimethanol can be suitably used.

  Here, the content of 1,4-cyclohexanedimethanol residues contained in the amorphous polyethylene terephthalate resin is preferably 15 mol% or more, preferably 20 mol% or more in all diol residues, and The upper limit is 50 mol% or less, preferably 40 mol% or less. If the content of 1,4-cyclohexanedimethanol residue is 15 mol% or more, a decrease in printability due to crystallization and embrittlement over time can be suppressed. While maintaining an appropriate viscosity at the time of melting, good film forming properties can be obtained. In addition, in 1,4-cyclohexanedimethanol, there are two types of isomers, cis type and trans type, which may be any.

The weight (mass) average molecular weight of the polyester resin composition used in the surface layer (S layer) is 30,000 or more, preferably 35,000 or more, more preferably 40,000 or more, and the upper limit is 80,000. Below, it is preferably 75,000 or less, more preferably 70,000. When the weight (mass) average molecular weight is 30,000 or more, an appropriate resin cohesive force can be obtained, and the film can be prevented from being insufficiently stretched or embrittled. On the other hand, if the weight (mass) average molecular weight is 80,000 or less, the melt viscosity can be lowered, which is preferable from the viewpoint of production and productivity improvement.

  The intrinsic viscosity (IV) of the polyester resin used in the surface layer (S layer) is 0.5 dl / g or more, preferably 0.6 dl / g or more, more preferably 0.7 dl / g or more, and the upper limit is 1.5 dl / g or less, preferably 1.2 dl / g or less, more preferably 1.0 dl / g or less. When the intrinsic viscosity (IV) is 0.5 dl / g or more, the deterioration of the film strength characteristics can be suppressed. On the other hand, if the intrinsic viscosity (IV) is 1.5 dl / g or less, breakage and the like accompanying an increase in stretching tension can be prevented.

  As a commercial item of the said polyester-type resin, "PETGpolyester6763" (made by Eastman Chemical Co., Ltd.), "SKYGREEN PETG" (made by SK Chemical Co., Ltd.) etc. are mentioned, for example.

  It is also useful to mix a crystalline polyester resin represented by polybutylene terephthalate or polybutylene terephthalate copolymerized with polyether in the surface layer (S layer) of the film of the present invention. As described above, when using a heat-shrinkable film, it usually involves printing and a bag making process using a solvent, so that the crystallinity of the constituent material itself is lowered in order to improve printability and solvent sealability. It will be necessary. However, if the resin of the constituent material is made completely amorphous, it is difficult to sufficiently satisfy the characteristics required for a heat-shrinkable film. Therefore, depending on the application, it may be preferable to impart appropriate crystallinity to the surface layer (S layer) of the film.

  A heat-shrinkable film made only of an amorphous polyester-based resin has a sudden rise in a shrinkage curve and a very high shrinkage stress depending on its viscoelastic properties. On the other hand, mixing a crystalline polyester resin and imparting appropriate crystallinity reduces the heat shrinkage rate at high temperatures, resulting in a gentler heat shrinkage curve, which improves the shrink finish of the film. I can expect.

  Furthermore, the thickness precision of the film after extending | stretching can be improved by mixing crystalline polyester-type resin and providing crystallinity. That is, in the initial stage of the stretching process, when the film to be heated is partially viewed, the temperature distribution may be uneven. In this case, stretching is started from the high temperature portion. When the resin used is an amorphous polyester-based resin, the stretched and thinned portion is further stretched, and the entire film is stretched unevenly. However, when crystallinity is imparted by mixing a crystalline polyester-based resin, the initially stretched portion becomes thin, and the stretching stress increases due to orientation crystallization, so that the unstretched portion is easily stretched. As a result, the entire film can be stretched uniformly, and the thickness accuracy can be improved.

  When the crystalline polyester resin is mixed with the surface layer (S layer), it is 1 part by mass or more, preferably 3 parts by mass or more with respect to 100 parts by mass of the thermoplastic polyester resin constituting the surface layer (S layer). More preferably, it is 5 parts by mass or more and 30 parts by mass or less, preferably 25 parts by mass or less, and more preferably 20 parts by mass. In particular, if the content of the crystalline polyester resin is 1 part by mass or more, it is possible to impart appropriate crystallinity to the film, it is easy to adjust the lower limit of the shrinkage stress specified in the present invention to 5 MPa or more, and the film shrinks more slowly. Therefore, good shrinkage finish can be expected. Further, if the content of the crystalline polyester resin is 30 parts by mass or less, it is easy to adjust the upper limit of the shrinkage stress specified in the present invention to 8 MPa or less, the shrinkage characteristic can be maintained, and printability and solvent sealability are hindered. And can be suitably used as a heat shrink film.

  In addition to the polyester resin, the polyester resin used in the surface layer (S layer) is a high melting point / high crystalline aromatic polyester as a hard segment, and an amorphous polyester or amorphous polyester as a soft segment. A thermoplastic polyester elastomer composed of ether or the like may be appropriately contained. These may be used alone or in combination of two or more thereof in the polyester resin.

<Intermediate layer (M layer)>
In the present invention, a styrene resin composition is used as a resin for forming the intermediate layer (M layer) of the film. Among these, block copolymerization of a styrene hydrocarbon and a conjugated diene hydrocarbon is particularly preferably used. Examples of the styrenic hydrocarbon include polystyrene, poly (p-, m- or o-methylstyrene), poly (2,4-, 2,5-, 3,4- or 3,5-dimethylstyrene), Polyalkylstyrenes such as poly (pt-butylstyrene); poly (o-, m- or p-chlorostyrene), poly (o-, m- or p-bromostyrene), poly (o-, m- Or p-fluorostyrene), poly (halogenated styrene) such as poly (o-methyl-p-fluorostyrene); polyhalogenated substituted alkylstyrene such as poly (o-, m- or p-chloromethylstyrene); poly ( p-, m-, or o-methoxystyrene), poly (o-, m-, or p-ethoxystyrene) and other polyalkoxystyrenes; poly (o-, m-, or p-carboxymethylstyrene), etc. Li carboxyalkyl styrene, poly (p- trimethylsilylstyrene) polyalkyl silyl styrene such as; poly (p- vinylbenzyl ether) and poly alkyl ether styrene more polyvinyl benzyl dimethoxyphosphinyl sulfide, and the like. The styrenic hydrocarbon block may contain a homopolymer, a copolymer and / or a copolymerizable monomer other than the styrenic hydrocarbon in the block.

  Examples of conjugated diene hydrocarbons include butadiene, isoprene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like. It is done. The conjugated diene hydrocarbon block may contain a copolymerizable monomer other than these homopolymers, copolymers and / or conjugated diene hydrocarbons in the block.

  One of the copolymerization of a styrenic hydrocarbon and a conjugated diene hydrocarbon that is preferably used in the intermediate layer (M layer) is styrene in which the styrene hydrocarbon is styrene and the conjugated diene hydrocarbon is butadiene. -Butadiene copolymer (SBS). The styrene content of SBS is 60% by mass or more, preferably 65% by mass or more, and more preferably 70% by mass or more. The upper limit of the styrene content is 95% by mass, preferably 90% by mass, and more preferably 85% by mass. If the content of styrene is 60% by mass or more, the effect of impact resistance can be exhibited, and by setting the upper limit to 95% by mass, the elastic modulus of the film at a temperature around room temperature is maintained, and good elasticity is achieved. Can be obtained. The polymerization form in the case of using a styrene-butadiene copolymer as the styrene resin is not particularly limited, and may be any form of a block copolymer, a random copolymer, and a graft copolymer, but a pure structure A block copolymer including a random structure and a tapered structure is preferred.

  Another example of a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon preferably used in the present invention is a styrene-isoprene-butadiene block copolymer (SIBS). In SIBS, the mass% ratio of styrene / isoprene / butadiene is preferably (60-90) / (5-40) / (5-30), (60-85) / (10-30) / ( 5 to 25) is more preferable, and (60 to 80) / (10 to 25) / (5 to 20) is more preferable. Moreover, the measured value of MFR of SIBS (measurement conditions: temperature 200 ° C., load 49 N) is 2 g / 10 minutes or more, preferably 3 g / 10 minutes or more, and 15 g / 10 minutes or less, preferably 10 g / 10 minutes. In the following, it is more preferable that it is 8 g / 10 min or less. If the butadiene content is high and the isoprene content is low, the butadiene heated inside the extruder or the like may cause a cross-linking reaction to increase the gel-like material. On the other hand, if the butadiene content is low and the isoprene content is high, the raw material unit price may increase and the production cost may increase.

  Moreover, the said styrene resin may be used independently, and 2 or more types of styrene resins from which styrene content rate differs may be mixed and used. Further, the styrenic resin comprises a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon, and a copolymer of a monomer copolymerizable with the copolymer and the styrene hydrocarbon or the conjugated diene hydrocarbon. It may be a polymer or a mixture with a homopolymer of a styrene hydrocarbon.

  For example, when the styrenic resin is a mixture of SBS and SIBS, the mass% ratio of SBS / SIBS is preferably about (90 to 10) / (10 to 90), and (80 to 20) / ( More preferably, it is about 20-80), more preferably about (70-30) / (30-70).

  When using a copolymer of a styrene-based hydrocarbon and an aliphatic unsaturated carboxylic acid ester, the aliphatic unsaturated carboxylic acid ester includes methyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. , Lauryl (meth) acrylate, and stearyl (meth) acrylate can be used for copolymerization. Preferably, it is a copolymer of styrene and butyl (meth) acrylate, more preferably styrene is in the range of 70% by mass to 90% by mass, and Tg (peak temperature of loss elastic modulus E ″). A melt flow rate (MFR) measurement value (measurement condition: temperature 200 ° C., load 49 N) of 2 g / 10 min or more and 15 g / 10 min or less is used. In addition, the said (meth) acrylate shows an acrylate and / or a methacrylate.

  The molecular weight of the styrenic resin composition has a mass (weight) average molecular weight (Mw) of 100,000 or more, preferably 150,000 or more, and an upper limit of 500,000 or less, preferably 400,000 or less, more preferably. Is less than 300,000. If the mass (weight) average molecular weight of the styrene-based resin composition is 100,000 or more, it is preferable without any defects that cause deterioration of the film. Furthermore, it is preferable that the mass (weight) average molecular weight of the polystyrene-based resin is 500,000 or less because there is no need to adjust the flow characteristics and there are no defects such as deterioration of extrudability.

  The melt flow rate (MFR) measured value (measurement conditions: temperature 200 ° C., load 49 N) of the styrene-based resin composition is 2 g / 10 minutes or more, preferably 3 g / 10 minutes or more, and the upper limit is 15 g / 10 minutes. Hereinafter, it is preferably 10 g / 10 min or less, more preferably 8 g / 10 min or less. When the MFR is 2 g / 10 min or more, the flow viscosity at the time of extrusion molding is appropriate, and the productivity is excellent. Moreover, if MFR is 15 g / 10min or less, since the cohesive force of resin is appropriate, the mechanical strength of the film is good, which is practically preferable.

The storage elastic modulus (E ′) at 0 ° C. of the styrene-based resin composition contained in the intermediate layer (M layer) is preferably 1.00 × 10 ⁹ Pa or more, and 1.50 × 10 ⁹ Pa or more. More preferably. The storage elastic modulus (E ′) at 0 ° C. represents the rigidity of the film, that is, the strength of the film. By having a storage elastic modulus (E ′) of 1.00 × 10 ⁹ Pa or more, when the laminated film is formed, it is possible to give the laminated film rigidity (rigidity at room temperature). In particular, when the thickness of the laminated film is reduced, the film that is made in a plastic bottle or other container is covered with a labeling machine, etc. to prevent the film from being slanted or the yield from being lowered due to film folding. This is preferable. This storage elastic modulus (E ′) is a simple substance of the above-mentioned styrene-based hydrocarbon and conjugated diene-based hydrocarbon block copolymer, a mixture of the two or more types of the copolymer, or other in a range not impairing transparency. It is obtained by mixing with a resin.

  When the styrene resin composition contained in the intermediate layer (M layer) is a mixture of a block copolymer of styrene hydrocarbons and conjugated diene hydrocarbons having different styrene contents or a mixture of other resins If a resin that bears fracture resistance and a resin that bears rigidity are appropriately selected, good results can be obtained. That is, by combining a styrene hydrocarbon-conjugated diene hydrocarbon block copolymer having high fracture resistance and the copolymer having high rigidity, or a styrene hydrocarbon-conjugated diene system having high fracture resistance. Mixing the hydrocarbon block copolymer with another type of resin having high rigidity, the total composition of those styrenic hydrocarbon-conjugated diene hydrocarbons, or a mixture of these with other types of resins However, it can adjust so that the storage elastic modulus (E ') in 0 degreeC desired may be satisfy | filled.

Preferred as the styrene-based hydrocarbon-conjugated diene-based hydrocarbon block copolymer capable of imparting fracture resistance are pure block SBS and random block SBS. Among them, the storage elastic modulus (E ′) at 0 ° C. is 1.00 × 10 ⁸ Pa or more and 1.00 × 10 ⁹ Pa or less, and at least one peak temperature of the loss elastic modulus (E ″) is − Those having viscoelastic properties at 20 ° C. or lower are preferred. If the storage elastic modulus at 0 ° C. is 1.0 × 10 ⁸ Pa or more, waist strength can be imparted by increasing the blend amount of the resin responsible for rigidity. On the other hand, at the peak temperature of the loss elastic modulus (E ″), the temperature on the low temperature side mainly shows fracture resistance. Although the characteristics vary depending on the stretching conditions, it is difficult to impart sufficient film breakability to the laminated film when the peak temperature of the loss modulus (E ″) is not below −20 ° C. before stretching. It may become.

As a resin capable of imparting rigidity, a copolymer containing a styrene hydrocarbon having a storage elastic modulus (E ′) at 0 ° C. of 2.00 × 10 ⁹ Pa or more, for example, a styrene hydrocarbon having a controlled block structure And block copolymers of conjugated diene hydrocarbons, polystyrene, styrene hydrocarbons and aliphatic unsaturated carboxylic acid ester copolymers.

As the styrene hydrocarbon-conjugated diene hydrocarbon block copolymer having a controlled block structure, the storage elastic modulus (E ′) at 0 ° C. is 2.00 × 10 ⁹ as a characteristic of the styrene-butadiene block copolymer. SBS that is Pa or higher is exemplified. The composition ratio of styrene-butadiene of SBS satisfying this is preferably adjusted to about styrene / butadiene = (95-80) / (5-20).

  Examples of polymerization methods that can satisfy the above viscoelastic properties are shown below. Usually, after a part of styrene or butadiene is charged to complete the polymerization, a mixture of styrene monomer and butadiene monomer is charged and the polymerization reaction is continued. This preferentially polymerizes butadiene having a higher polymerization activity, and finally a block composed of a single monomer of styrene is generated. For example, when styrene is homopolymerized first, and after the polymerization is completed, a mixture of styrene monomer and butadiene monomer is added and polymerization is continued, the styrene / butadiene monomer ratio gradually changes between the styrene block and the butadiene block. A styrene-butadiene block copolymer having a copolymer site is obtained. By providing such a site, a polymer having the above viscoelastic properties can be obtained. In this case, the two peaks attributed to the butadiene block and the styrene block as described above cannot be clearly confirmed, and it seems that only one peak apparently exists. That is, in a block structure such as SBS of a random block in which a pure block and a butadiene block are clearly present, Tg due to the butadiene block is mainly present at 0 ° C. or less, and therefore, storage modulus at 0 ° C. ( It becomes difficult for E ′) to be not less than a predetermined value. Further, regarding the molecular weight, the MFR measurement value (measurement conditions: temperature 200 ° C., load 49 N) is adjusted to 2 g / 10 min or more and 15 g / 10 min or less. The mixing amount of the styrene-butadiene block copolymer imparting rigidity is appropriately adjusted according to the characteristics of the heat-shrinkable laminated film, and is preferably 20% by mass or more of the total amount of the resin constituting the intermediate layer (M layer). Is 40% by mass or more, and 80% by mass or less, preferably 70% by mass or less. If it is 80 mass% or less of resin total amount, the rigidity of a film can be improved significantly and it can suppress that fracture resistance falls. On the other hand, if it is 20 mass% or more of the total resin amount, sufficient rigidity can be imparted to the film.

  The content of the styrenic resin composition is 50% by mass or more, preferably 65% by mass or more, and more preferably 80% by mass or more, based on the total amount of resin forming the intermediate layer (M layer). . However, when general-purpose polystyrene (GPPS) is contained, TPS of PPPS (peak temperature of loss elastic modulus E ″) is as high as about 100 ° C., so the content of GPPS to be mixed is an intermediate layer (M layer) It is desirable that the total amount of the resin constituting is 40% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less.

  If the styrene resin contained in the intermediate layer (M layer) is contained in an amount of 50% by mass or more of the total amount of the resin forming the intermediate layer (M layer) as described above, other resins can be mixed. Examples of such resins include polyester resins, polyolefin resins, acrylic resins, polycarbonate resins, etc. Among them, it is preferable to use polyester resins.

The styrenic resin composition constituting the intermediate layer (M layer) has a tensile modulus of 1000 MPa or more, preferably 1100 MPa or more, more preferably 1200 MPa or more in the direction orthogonal to the film main shrinkage direction when an unstretched film is formed. It is desirable to use a person who gives If it is a styrene-based resin composition that gives a tensile modulus of 1000 MPa or more, the resulting laminated film is highly elastic as a whole, and even when the thickness of the laminated film is reduced, bags are made in containers such as PET bottles. When the film is covered with a labeling machine or the like, it is possible to suppress the occurrence of problems such as being covered at an angle or the yield is likely to decrease due to the film being folded back.
The “non-stretched film” refers to a film formed using a styrene resin composition as a raw material, and obtained without stretching during film formation.

  Examples of commercially available styrenic resin compositions include “Clearen” (manufactured by Denki Kagaku Kogyo Co., Ltd.), “Asaflex” (manufactured by Asahi Kasei Chemicals), “Styloflex” (manufactured by BASF Japan), and “K Resin”. (Chevron Philips Chemical Co., Ltd.).

<Adhesive layer (AD layer)>
The adhesive layer (AD layer) in the present invention contains a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon or a hydrogenated derivative thereof. Here, styrene is suitably used as the styrene-based hydrocarbon, and styrene homologues such as α-methylstyrene can also be used. Examples of the conjugated diene hydrocarbon include 1,3-butadiene, isoprene, 1,3-pentadiene and the like, and these can be used alone or in admixture of two or more. Furthermore, the adhesive layer (AD layer) may contain a small amount of components other than styrene-based hydrocarbons and conjugated diene-based hydrocarbons as the third component. In addition, when there are many double bonds mainly composed of vinyl bonds in the conjugated diene hydrocarbon portion, it is possible to improve compatibility with the polyester resin of the surface layer (S layer) and to improve the interlayer adhesive strength. preferable.

  When a copolymer of styrene hydrocarbon and conjugated diene hydrocarbon or a hydrogenated derivative thereof is used as an adhesive layer (AD layer), the content of styrene hydrocarbon is 5% by mass or more, preferably 7% by mass or more. More preferably, it is 10% by mass or more and 40% by mass or less, preferably 37% by mass or less, more preferably 35% by mass or less. If the content of styrenic hydrocarbon is 5% by mass or more, when the film is regenerated and added to the surface layer (S layer) and / or the intermediate layer (M layer) (especially regenerated and added to the intermediate layer (M layer)) Is preferable), since a film having good compatibility and maintaining transparency can be obtained. On the other hand, if the content of styrene-based hydrocarbons is 40% by mass or less, the adhesive layer (AD layer) is rich in flexibility. For example, when stress or impact is applied to the entire film, the surface layer (S layer) Since the relaxation effect to the stress generated between the intermediate layer (M layer) works, delamination can be suppressed.

  Further, the glass transition temperature (Tg) of the copolymer of the styrene-based hydrocarbon and the conjugated diene-based hydrocarbon or the hydrogenated derivative thereof is preferably 20 ° C. or less, and more preferably 10 ° C. or less. More preferably, it is 0 ° C. or lower. Here, if the glass transition temperature (Tg) is 20 ° C. or lower, when a force is applied to the laminated film, the flexible adhesive layer (AD layer) plays a role as a buffering material, so that delamination can be suppressed. Practically preferred.

In addition, the glass transition temperature (Tg) used in this invention is the value calculated | required as follows. That is, using a viscoelastic spectrometer DVA-200 (manufactured by IT Measurement Co., Ltd.), measurement was performed at a vibration frequency of 10 Hz, a strain of 0.1%, and a heating rate of 3 ° C./min. The peak value of E ″) was obtained, and the temperature at that time was defined as the glass transition temperature (Tg). When there are multiple peaks of loss modulus (E ″), the loss modulus (E ″) is the highest. The temperature of the peak value indicating the value is defined as the glass transition point (Tg).

  Commercially available products of the above-mentioned copolymers include, for example, styrene-butadiene block copolymer elastomer (Asahi Kasei Chemicals Co., Ltd., trade name “Tufprene”), hydrogenated derivatives of styrene-butadiene block copolymers (Asahi Kasei Chemicals Co., Ltd.). ) Product name “Tuftec H”, Shell Japan Co., Ltd. “Clayton G”), hydrogenated derivative of styrene-butadiene random copolymer (JSR Co., Ltd. product name “Dynalon”), styrene-isoprene block co-weight Examples thereof include hydrogenated derivatives of coal (Kuraray Co., Ltd., trade name “Septon”), styrene-vinylisoprene block copolymer elastomer (Kuraray Co., Ltd., trade name “Hibler”), and the like.

  Further, a copolymer of styrene hydrocarbon and conjugated diene or a hydrogenated derivative thereof can further improve interlayer adhesion with a surface layer (S layer) made of a polyester resin composition by introducing a polar group. Can do. Examples of polar groups to be introduced include acid anhydride groups, carboxylic acid groups, carboxylic acid ester groups, carboxylic acid chloride groups, carboxylic acid amide groups, carboxylic acid groups, sulfonic acid groups, sulfonic acid ester groups, and sulfonic acid chloride groups. Sulfonic acid amide group, sulfonic acid group, epoxy group, amino group, imide group, oxazoline group, hydroxyl group and the like.

  Typical examples of the copolymer of a vinyl aromatic compound having a polar group introduced therein and a conjugated diene or a hydrogenated derivative thereof include maleic anhydride-modified SEBS, maleic anhydride-modified SEPS, epoxy-modified SEBS, and epoxy-modified SEPS. These copolymers can be used alone or in admixture of two or more.

  As a commercial item of said copolymer, Asahi Kasei Chemicals Co., Ltd. brand name "Tuftec M", Daicel Chemical Co., Ltd. brand name "Epofriend" etc. are mentioned, for example.

  In the present invention, the surface layer (S layer), the intermediate layer (M layer), and the adhesive layer (AD layer), in addition to the components described above, within the range that does not significantly impair the effects of the present invention, moldability, production Recycled resin generated from trimming loss such as film ears, inorganic particles such as silica, talc, kaolin, calcium carbonate, titanium oxide, carbon black, etc. Additives such as pigments, flame retardants, weather resistance stabilizers, heat resistance stabilizers, antistatic agents, melt viscosity improvers, crosslinking agents, lubricants, nucleating agents, plasticizers and anti-aging agents may be added as appropriate. It is desirable that recycled resin generated from trimming loss such as film ears is regenerated and added to the surface layer (S layer) and / or the intermediate layer (M layer), preferably the intermediate layer (M layer).

  In the film of the present invention, a layer for imparting heat resistance (hereinafter referred to as “heat-resistant layer”) can be formed on the surface layer (S layer). Examples of the raw material constituting the heat resistant layer include various surfactants. The surfactant is conventionally used as an antistatic agent or an antistatic agent, and it can be mixed with a predetermined resin to form a coating layer on the film surface to provide an antistatic or antistatic effect. It was known until. However, it is not yet known that surfactants can impart heat resistance. As a result of diligent investigation on the surfactant, the present inventor has improved the heat resistance of the film by laminating a surfactant (particularly a cationic surfactant or an amphoteric surfactant) on the surface layer (S layer). I found out. By forming such a heat-resistant layer on the surface layer (S layer), for example, when a heated PET bottle is heated with a heater, the PET bottle film is fused to the heating plate. In addition, the PET bottle films can be effectively prevented from fusing together.

  The surfactant is not particularly limited, and various surfactants can be used. Anionic surfactants include low molecular weight compounds such as fatty acid amine salts, alkyl phosphate types, alkyl sulfate types, and alkyl allyl sulfate types, as well as high molecular weight types such as polyalkylene sulfates and copolymers thereof. It can be illustrated. Examples of the cationic surfactant include alkylamine sulfate type, quaternary ammonium salt type, quaternary ammonium resin type, pyridium salt, morpholine derivative and the like. Examples of the nonionic surfactant include sorbitan type, ether type, amine type, amide type, ethanolamide type, fatty acid glycerin ester, alkylpolyethyleneimine and the like. Examples of zwitterionic surfactants include alkyl betaine type, alkyl imidazoline derivatives, N-alkyl, β-alanine type and the like.

  The heat-resistant layer can be formed by applying a coating solution in a state where the surfactant is dissolved in a solvent. As the medium, water or a mixed solvent of water and a water-soluble organic solvent can be used. Examples of the water-soluble organic solvent include alcohols such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, tert-butyl alcohol, and 1,2-propylene alcohol, ethylene glycol, propylene glycol, diethylene glycol, and ethylene glycol monomethyl ether. , Glycols such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, ethylene glycol monophenyl ether or derivatives thereof, ketones such as acetone and diacetone alcohol, other water-soluble ethers and water-soluble esters And the like are preferable.

Examples of the coating method for the surface layer (S layer) include spray coating, air knife coating, river coating, kiss coating, gravure coating, reverse roll coating, die coating, Mayer bar, and roll brushing. A bar coating method, a reverse kiss coating method, an offset gravure coating method, a doctor blade method, a curtain coating method, a dipping method, and the like can be applied alone or in combination. The coating amount of the coating solution, but is no particular limitation, to obtain a desired heat effect for example, 0.0005 g / m ² or more 0.5 g / m ² or less as solid content, preferably 0.001 g / m is preferably ² or more 0.1 g / m ² or less.

<Layer structure of film>
The heat-shrinkable film of the present invention is not particularly limited as long as it has at least three layers having an adhesive layer (AD layer) between the surface layer (S layer) and the intermediate layer (M layer). Here, the surface layer (S layer) may have the same layer as the intermediate layer other than the surface layer and the surface layer.

  A preferred laminated structure in the present invention is a five-layer structure comprising a surface layer (S layer) / adhesive layer (AD layer) / intermediate layer (M layer) / adhesive layer (AD layer) / surface layer (S layer). By adopting this layer structure, the shrinkage finish properties, film stiffness, natural shrinkage, transparency at the time of regeneration addition, which are the objects of the present invention, are good, and delamination and shrinkage stress of the film are suppressed. In addition, a heat-shrinkable laminated film suitable for applications such as shrink wrapping, shrink-bound wrapping, and shrink labels can be obtained with good productivity and economy.

  Next, a surface layer (S layer), an intermediate layer (M layer), and an adhesive layer (AD layer) which are one of the preferred embodiments of the present invention (S layer) / (AD layer) / (M layer) A film having a five-layer structure of / (AD layer) / (S layer) will be described.

  In the present invention, the thickness ratio of the surface layer (S layer) to the thickness of the entire film is 10% or more, preferably 20% or more, more preferably 30% or more, and the upper limit is 75% or less, preferably 70% or less. More preferably, it is 65% or less. A thickness ratio of the surface layer (S layer) of 10% or more is preferable because the shrinkage stress can be easily adjusted to the lower limit of 5 MPa or more specified in the present invention, and the film becomes high. On the other hand, if the thickness ratio of the surface layer (S layer) is 75% or less, it is easy to adjust the shrinkage stress to the upper limit of 8 MPa or less stipulated in the present invention, the shrinkage behavior is gradual, and the shrink finish is good. Therefore, it is preferable. Next, the thickness ratio of the intermediate layer (M layer) to the thickness of the entire film is 20% or more, preferably 30% or more, and the upper limit is 80% or less, preferably 70% or less. Furthermore, the adhesive layer (AD layer) has a function of 0.5 μm or more and 6 μm or less, preferably 1 μm or more and 5 μm or less. A heat-shrinkable laminated film suitable for applications such as shrink wrapping, shrink-bound wrapping and shrinkage labels, which is excellent and suppresses natural shrinkage and delamination of the film, can be obtained with a good balance.

When a heat-resistant layer is disposed on the surface layer (S layer), the heat-resistant layer is 0.0006 g / m ² or more, preferably 0.0015 g / m ² or more, more preferably 0.0045 g / m ² or more. Apply to. If desired heat resistance is obtained, it is not necessary to apply more than necessary, and the maximum value of the coating amount and thickness can be set in light of the cost.

  The heat resistance of the film is evaluated by, for example, winding the obtained heat-shrinkable film and superimposing the outer surfaces (in the case of a film coated with an antistatic agent) with the tester industry Heat Seal Tester TP-701-A. The sample was heated from 70 ° C. to 120 ° C. at an interval of 1 ° C. under a pressure of 0.1 MPa and held for 1 minute, and then the sample was cut into a predetermined size and peeled off from the film end. It can be evaluated by confirming the presence or absence of fusion.

<Physical and mechanical properties of film>
The film of the present invention has a thermal shrinkage rate in the main shrinkage direction of 10% or more and 40% or less, preferably 10% or more and 35% or less when immersed in warm water at 70 ° C. for 10 seconds, and is heated in 80 ° C. hot water for 10 seconds. The thermal shrinkage rate in the main shrinkage direction when immersed is 30% to 70%, preferably 35% to 65%.

  This is an index for determining the adaptability to the shrinking process in a relatively short time (several seconds to about several tens of seconds) such as the use of shrinkage labels for PET bottles. For example, the required shrinkage required for a heat-shrinkable film applied to a shrinkage label for a PET bottle varies depending on its shape, but is generally about 2% to 70%.

  Further, the shrinkage processing machine that is most commonly used industrially for label mounting of PET bottles is generally called a steam shrinker that uses steam as a heating medium for shrinking. Furthermore, the heat-shrinkable film needs to be sufficiently heat-shrinked at a temperature as low as possible from the viewpoint of the influence of heat on the object to be coated. However, in the case of a film with high temperature dependence and extremely different shrinkage ratios depending on the temperature, parts with different shrinkage behavior tend to occur with respect to the temperature spots in the steam shrinker, so shrinkage spots, wrinkles, avatars, etc. occur. However, the shrink-finished appearance tends to deteriorate. From the viewpoint of including these industrial productivity, if the film has a thermal shrinkage rate within the range of the above conditions, it can be sufficiently adhered to the object to be coated within the shrinkage processing time, and no spots, wrinkles or avatars are generated. This is preferable because a good shrink-finished appearance can be obtained.

  When the film of the present invention is used as a heat-shrinkable label, the shrinkage rate in the direction (longitudinal direction) perpendicular to the main shrinkage direction of the film is 10% or less when heated in 80 ° C. warm water for 10 seconds. It is preferably 5% or less, more preferably 3% or less, and preferably 10% or less when heated in 70 ° C. warm water for 10 seconds. More preferably, it is more preferably 3% or less. Here, if the film has a heat shrinkage rate of 10% or less in the direction orthogonal to the main shrinkage direction, the dimension itself in the direction orthogonal to the main shrinkage direction after shrinkage is shortened, or the printed pattern or character after shrinkage is shortened. In the case of a square bottle, distortion or the like is likely to occur, and troubles such as vertical sink can be suppressed.

  The natural shrinkage rate of the film of the present invention is desirably as small as possible. Generally, the natural shrinkage rate of a heat-shrinkable film is, for example, a natural shrinkage rate of 30% or less after storage at 30 ° C. for 30 days, preferably It is desirable that it is 2.0% or less, more preferably 1.5% or less. If the natural shrinkage rate under the above conditions is 3.0%, even if the produced film is stored for a long period of time, it can be stably attached to a container or the like, and it is difficult to cause problems in practice.

  Regarding the transparency of the film of the present invention, the haze value measured according to JIS K7105 is preferably 10% or less, more preferably 7% or less, and even more preferably 5% or less. If the haze value is 10% or less, the transparency of the film can be obtained and a display effect can be obtained.

  Moreover, the film of the present invention is, for example, a film having an intermediate layer (M layer) of 50 parts by mass or less, preferably 45 parts by mass or less, more preferably 40 parts by mass or less with respect to 100 parts by mass of the film (generated during film production) In the case of regenerating and adding a trimming loss product such as a film ear), the haze value is 10% or less, preferably 7% or less, more preferably 5% when a film having a thickness of 50 μm is measured according to JIS K7105. The following is preferable. If the haze value after regeneration addition is 10% or less, good transparency can be maintained even during reuse.

  The mechanical strength of the film of the present invention is evaluated by the tensile elongation at break measured in accordance with JIS K7127. In a tensile test at a test speed of 200 mm / min in an environment of −5 ° C., particularly for a label application, In the take-up (flow) direction (MD), the tensile elongation at break is 100% or more, preferably 200% or more, more preferably 300% or more.

  The sealing strength of the film of the present invention is 3 N / 15 mm or more, preferably 4 N / 15 mm or more, more preferably 5 N / 15 mm or more, and 15 N / 15 mm width or less using the measurement method described in the examples described later. 12 N / 15 mm width or less. The seal strength here refers to the peel strength value of the seal portion when the film is formed into a cylindrical shape by a center seal described later. It should be noted that when the adhesive strength between the surface layer (S layer) and the adhesive layer (AD layer) or the adhesive layer (AD layer) and the intermediate layer (M layer) is poor, when measuring the seal strength, There is a possibility that delamination, not delamination, may precede, and sufficient seal strength cannot be ensured. Since the film of the present invention has a sufficient interlayer adhesion and has a seal strength of 3 N / 15 mm or more, troubles such as peeling of the seal portion during use do not occur.

<Film production method>
The film of the present invention can be produced by a known method. The form of the film may be either flat or tube-like, but the flat form is preferable in terms of productivity (a few products can be taken in the width direction of the original film) and printing on the inner surface. . As a method for producing a flat film, for example, a resin is melted by using a plurality of extruders, co-extruded from a T die, solidified by cooling with a chilled roll, roll-stretched in the vertical direction, and tenter-stretched in the horizontal direction. An example is a method of obtaining a film by winding, annealing, cooling, and winding with a winder (corona discharge treatment is applied to the surface when printing is performed). Moreover, the method of cutting open the film manufactured by the tubular method and making it flat is also applicable.

  Among the various properties of the film, the shrinkage property and the shrinkage stress mainly depend on the stretching temperature and the stretching ratio, and the higher the shrinkage property and the shrinking stress are, the higher the temperature and the low temperature stretching, and the heat treatment after annealing (annealing, In particular, it is also affected by relaxation heat treatment. The stretching temperature needs to be changed depending on the Tg of the resin composition used and the properties required for the heat-shrinkable film, but is generally 60 ° C. or higher, preferably 70 ° C. or higher, more preferably 80 ° C. or higher, and the upper limit is 120 ° C. In the following, it is preferably controlled in the range of 110 ° C. or lower, more preferably 100 ° C. or lower. When the stretching temperature is 60 ° C. or higher, the stretchability is good, and it is easy to adjust to the upper limit of 8 MPa or less of the shrinkage stress defined in the present invention. On the other hand, if the stretching temperature is 120 ° C. or lower, the elastic modulus of the material is appropriately maintained, so that it is easy to obtain a film with good thickness accuracy and the lower limit of the contraction stress specified in the present invention is adjusted to 5 MPa or more. Cheap.

  Moreover, although it is necessary to change the stretch ratio of the film depending on the glass transition temperature of the resin composition to be used and the characteristics required for the heat-shrinkable film, it can be generally adjusted to a range of 2 to 7 times in the main shrinkage direction. It is important, preferably 3 times or more, more preferably 4 times or more, and the upper limit is adjusted to be uniaxial or biaxial as appropriate within a range of 7 times or less. If the draw ratio is 2 times or more, it is easy to adjust the shrinkage stress to the upper limit of 8 MPa or less as defined in the present invention, and a film with good thickness accuracy is easily obtained. On the other hand, if the draw ratio is 7 times or less, it is easy to adjust the shrinkage stress to the upper limit of 8 MPa or less specified in the present invention. Even in the case of uniaxial stretching in the transverse direction, it is also effective to impart weak stretching of about 1.05 to 1.8 times in the longitudinal direction for the purpose of improving the mechanical properties of the film. Next, the stretched film is subjected to heat treatment or relaxation treatment at a temperature of about 50 ° C. or more and about 100 ° C. or less for the purpose of reducing shrinkage stress, natural shrinkage rate or improving heat shrinkage characteristics, if necessary. It cools rapidly within the time when the molecular orientation is not relaxed and becomes a heat-shrinkable film.

  The thickness of the film of the present invention is not particularly limited, but is usually 20 μm or more, preferably 30 μm or more, and the upper limit is 80 μm or less, preferably 70 μm or less. Here, if the thickness is 20 μm or more, the film is easy to handle. On the other hand, if it is 80 μm or less, the transparency and shrinkage workability are excellent, which is economically preferable. If necessary, surface treatment and surface processing such as corona treatment, printing, coating, and vapor deposition, and bag making processing and perforation processing using various solvents and heat sealing can be performed.

  The film of the present invention is processed from a flat shape to a cylindrical shape or the like according to an object to be packaged and provided for packaging. For things that require printing in cylindrical containers such as PET bottles, first print the required image on one side of a wide flat film wound up on a roll, and then cut the printed image to the required width. The center seal (the so-called envelope is attached to the seal portion) may be folded into an inner side to form a cylinder. As the center sealing method, an organic solvent bonding method, a heat sealing method, an adhesive method, and an impulse sealer method can be considered. Among these, from the viewpoint of productivity and appearance, an adhesion method using an organic solvent is preferably used.

[Molded products, heat-shrinkable labels and containers]
The film of the present invention is excellent in low-temperature shrinkage, shrinkage finish, transparency, natural shrinkage, etc. of the film, so its use is not particularly limited. By forming a functional layer, it can be used as various molded products such as bottles (blow bottles), trays, lunch boxes, prepared food containers, dairy products containers and the like. In particular, when the film of the present invention is used as a heat-shrinkable label for food containers (for example, PET bottles, glass bottles, preferably PET bottles for soft drinks or foods), a complicated shape (for example, a cylinder with a narrow center, corners, etc.) A rectangular column, pentagonal column, hexagonal column, etc.) can be adhered to the shape, and a container with a beautiful label without wrinkles or avatars can be obtained. The molded article and container of the present invention can be produced by using a normal molding method.

  Since the film of the present invention has excellent low-temperature shrinkage and shrinkage finish properties, in addition to the heat-shrinkable label material of a plastic molded product that is deformed when heated to a high temperature, the coefficient of thermal expansion, water absorption, etc. The material is very different from the heat shrinkable film, such as metal, porcelain, glass, paper, polyethylene, polypropylene, polybutene and other polyolefin resins, polymethacrylate resin, polycarbonate resin, polyethylene terephthalate, polybutylene terephthalate, etc. It can be suitably used as a heat-shrinkable label material for a package (container) using at least one selected from polyester-based resins and polyamide-based resins as a constituent material.

  As a material constituting the plastic package in which the film of the present invention can be used, in addition to the above resins, polystyrene, rubber-modified impact-resistant polystyrene (HIPS), styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, Styrene-maleic anhydride copolymer, acrylonitrile-butadiene-styrene copolymer (ABS), methacrylate-butadiene-styrene copolymer (MBS), polyvinyl chloride resin, phenol resin, urea resin, melamine resin, Examples thereof include an epoxy resin, an unsaturated polyester resin, and a silicone resin. These plastic packages may be a mixture of two or more resins or a laminate.

  The present invention will be described below with reference to examples. In addition, the measured value and evaluation which are shown to an Example were performed as follows. Here, the take-up (flow) direction of the laminated film is described as MD (Machine Direction), and the perpendicular direction thereof is described as TD (Transverse Direction).

(1) Tensile elasticity modulus It measured about the direction (MD) orthogonal to the main contraction direction of a film on the conditions of temperature 23 degreeC according to JISK7127. The results of evaluation based on the following criteria are also shown.
A: Tensile elastic modulus is 1400 MPa or more. O: Tensile elastic modulus is 1200 MPa or more and less than 1400 MPa. X: Tensile elastic modulus is less than 1200 MPa.

(2) Heat Shrinkage The film was cut into a size of MD 10 mm and TD 100 mm, and immersed in a hot water bath at 70 ° C., 80 ° C., and 90 ° C. for 10 seconds, and the amount of shrinkage was measured. For the thermal shrinkage, the ratio of shrinkage to the original size before shrinkage was expressed as a% value in the main shrinkage direction (TD) of the film.

(2) Shrinkage stress The film was cut into a size of MD 10 mm and TD 70 mm, chucked at an interval of 50 mm, and fixed so that the load cell was free from talmi. Thereafter, the specimen was immersed for 10 seconds in a silicone oil bath at 90 ± 0.5 ° C., and the maximum shrinkage stress in the film main shrinkage direction (TD) was measured. The shrinkage stress was calculated by applying the following formula.
Shrinkage stress (MPa) = Load applied to the load cell (N) / Cross sectional area of the sample piece (mm ² )

(3) Natural shrinkage The film was cut to a size of MD 50 mm and TD 1000 mm and left in a thermostatic chamber at 30 ° C. for 30 days, and the amount of shrinkage relative to the original size before shrinkage was measured in the main shrink direction (TD) of the film. The ratio was expressed as a% value.

(4) Haze value Based on JIS K7105, the haze value of the film was measured at a film thickness of 50 μm.

(5) Haze at the time of regeneration addition After the obtained heat-shrinkable film is pulverized by a pulverizer to be regenerated pellets, an amount corresponding to 50 parts by mass with respect to 100 parts by mass of the film is added to the intermediate layer (M layer) Regeneration was added, and a regeneration addition film was obtained in the same manner as in each Example. The haze value was measured based on JIS K7105 using the obtained reproduction | regeneration addition film.
◎: Haze value is less than 7% ○: Haze value is 7% or more and less than 10% ×: Haze value is 10% or more

(6) MD Low Temperature Tensile Breaking Elongation According to JIS K7127, measurement was performed in the direction (MD) perpendicular to the main shrinkage direction of the film under conditions of a temperature of −5 ° C. and a test speed of 200 mm / min. At this time, 20 test pieces were measured, and the average value of the results was defined as the MD low temperature tensile elongation at break.

(7) Seal strength At a position 10 mm from both ends of the TD of the film, it was adhered using a tetrohydrofuran (THF) solvent to produce a cylindrical label. The seal part is cut to a width of 15 mm in the circumferential direction (TD), and it is cut into a T-type peel strength at a test speed of 200 mm / min at TD with a constant temperature bath tensile tester ("201X" manufactured by Intesco Corporation). Tests were conducted and evaluated according to the following criteria.
◎: Seal strength is 5N / 15mm width or more ○: Seal strength is 4N / 15mm width or more and less than 5N / 15mm width ×: Seal strength is less than 3N / 15mm width

(8) Shrinkage finish The film which printed the grid of the 10 mm space | interval was cut out to the magnitude | size of MD100mmxTD298mm, the both ends of TD were piled up 10mm, and it adhered with the tetrohydrofuran (THF) solvent, and produced the cylindrical film. This cylindrical film was attached to a cylindrical PET bottle having a capacity of 1.5 L, and passed through the shrinking tunnel having a length of 3.2 m (3 zones) of the steam heating system in about 4 seconds without rotating. The atmospheric temperature in the tunnel in each zone was set to a range of 70 to 85 ° C. by adjusting the amount of steam with a steam valve. After film coating, the following criteria were evaluated.
◎: Shrinkage is sufficient and no wrinkles, avatars, and lattice distortions occur. ○: Shrinkage is sufficient, and wrinkles, avatars, and lattice distortions are very slight. ×: Shrinkage is sufficient, but wrinkles, avatars, and lattice distortions. Distortion is noticeable

(11) Popping out the contents Put water into a 500 mL PET bottle (using a bottle of “Marocha 500 mL” manufactured by Coca-Cola Japan Co., Ltd.) up to a height of 5 mm from the mouth, and cover the entire surface with a cylindrical film up to the neck of the bottle. Evaluation of whether or not the contents jump out of the mouth when the steam heating system is contracted by passing through the shrink tunnel of 3.2 m (3 zones) in length for about 4 seconds. did.
○: Almost no popping out △: Popping out occasionally ×: Popping out quite frequently

Example 1
As shown in Table 1, as a polyester resin composition of the surface layer (S layer), 100 parts by mass of PETG (copolyester 6663 manufactured by Eastman Chemical Co., Ltd.) (hereinafter abbreviated as “PETG”) and an average particle size of 2.4 μm. PBT containing 0.05% by mass of amorphous silica (Silicia 320 manufactured by Fuji Silysia Chemical Ltd.) (Polyplastics Juranex 2002, Tg = 45 ° C., Tm = 225 ° C.) (hereinafter abbreviated as “PBT1”) .) A mixed resin composition with 10 parts by mass was used. Further, as the styrene resin composition of the intermediate layer (M layer), SBS (styrene / butadiene = 90/10, storage elastic modulus E ′ = 2.5 × 10 ⁹ Pa, loss elastic modulus E ″ peak temperature = 54 ° C., Vicat softening point = 76 ° C., hereinafter abbreviated as “SBS1”) 45% by mass and SBS (styrene / butadiene = 71/29, storage elastic modulus E ′ = 2.1 × 10 ⁸ Pa, loss elastic modulus E ″ peak) Temperature = −46 ° C. and 84 ° C., Vicat softening point = 69 ° C., hereinafter abbreviated as “SBS2”) 100 parts by mass of mixed resin composition, and antioxidant (trade name, manufactured by Sumitomo Chemical Co., Ltd.) : Sumilizer GS) A resin composition containing 0.2 part by mass was used. Further, as a copolymer of a styrene-based hydrocarbon and a conjugated diene-based hydrocarbon in the adhesive layer (AD layer), SIS (Clayton D1124 manufactured by JSR Kraton Polymer Co., Ltd., styrene content 30% by mass, Tg = −56 ° C., hereinafter “ Abbreviated as “AD1”). The raw materials constituting each layer are put into separate twin-screw extruders manufactured by Mitsubishi Heavy Industries, Ltd., and after melt mixing at a set temperature of 240 ° C., the thickness of each layer is the surface layer (S layer) / adhesive layer (AD layer) / intermediate Layer (M layer) / adhesive layer (AD layer) / surface layer (S layer) = 55 μm / 7 μm / 151 μm / 7 μm / 55 μm Co-extruded from 3 types and 5 layers dies, taken up by cast roll at 60 ° C., cooled By solidifying, an unstretched laminated sheet having a width of 300 mm and a thickness of 275 μm was obtained. Next, in a film tenter facility manufactured by Kyoto Machine Co., Ltd., the film was stretched 5.5 times in the transverse uniaxial direction at a preheating temperature of 100 ° C. and a stretching temperature of 85 ° C., and then heat-treated at 95 ° C. for 6 seconds. A shrinkable laminated film was obtained.
Moreover, after the obtained heat-shrinkable film was pulverized with a pulverizer to be regenerated pellets, an amount corresponding to 50 parts by mass with respect to 100 parts by mass of the film was regenerated and added to the intermediate layer (M layer), In the same manner as above, a heat-shrinkable laminated film after addition of regeneration was obtained.
Moreover, after the obtained heat-shrinkable film was pulverized with a pulverizer to be regenerated pellets, an amount corresponding to 50 parts by mass with respect to 100 parts by mass of the film was regenerated and added to the intermediate layer (M layer), In the same manner as above, a heat-shrinkable laminated film after addition of regeneration was obtained. The resin composition of the intermediate layer (M layer) after regeneration addition is 42 parts by mass of the resin composition constituting the front and back layers (S layer) with respect to 100 parts by mass of the styrene resin composition constituting the intermediate layer, and the adhesive layer. The resin composition constituting (AD layer) was 4 parts by mass.
A film having no problem with respect to all of the evaluation items was evaluated as (◯), and a film having at least one problem was evaluated as (×). The evaluation results are shown in Table 2.

(Example 2)
As shown in Table 1, the heat-shrinkable laminated film was the same as in Example 1 except that the content of PBT used for the surface layer (S layer) was changed to 15 parts by mass and the stretching temperature was changed to 80 ° C. And the heat-shrinkable laminated film after regeneration addition was obtained. The results of evaluating the obtained film are shown in Table 2.

(Example 3)
As shown in Table 1, the mass ratio of the PETG and PBT mixed resin composition used for the surface layer (S layer) was changed to PETG alone, and the thickness of each layer in the unstretched laminated sheet was changed to the surface layer (S layer). / Adhesive layer (AD layer) / Intermediate layer (M layer) / Adhesive layer (AD layer) / Surface layer (S layer) = Same as Example 1 except for changing to 69 μm / 7 μm / 123 μm / 7 μm / 69 μm A heat-shrinkable laminated film and a heat-shrinkable laminated film after regeneration addition were obtained. The results of evaluating the obtained film are shown in Table 2.

Example 4
As shown in Table 1, a heat-shrinkable laminated film was obtained in the same manner as in Example 1 except that the draw ratio in the transverse uniaxial direction was changed to 6.0 times. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 1)
As shown in Table 1, it does not have an adhesive layer (AD layer), and the composition of the intermediate layer (M layer) is changed from the mixed resin composition of SBS1 and SBS2 to PETG alone, as in Example 1. A heat-shrinkable laminated film and a heat-shrinkable laminated film after regeneration addition were obtained. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 2)
As shown in Table 1, a heat-shrinkable laminated film and a heat-shrinkable laminated film after addition of regeneration were obtained in the same manner as in Example 1 except that the draw ratio in the lateral uniaxial direction was changed to 7.5. . The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 3)
As shown in Table 1, in Example 1, the thickness of each layer in the unstretched laminated sheet was determined as follows: surface layer (S layer) / adhesive layer (AD layer) / intermediate layer (M layer) / adhesive layer (AD layer) / surface Layer (S layer) = 93 μm / 7 μm / 75 μm / 7 μm / 93 μm A heat-shrinkable laminated film and a heat-shrinkable laminated film after regeneration addition were obtained in the same manner as in Example 1 except that the layer was changed to 93 μm / 7 μm / 75 μm / 7 μm / 93 μm. The resin composition of the intermediate layer (M layer) after regeneration addition is 196 parts by mass of the resin composition constituting the front and back layers (S layer) with respect to 100 parts by mass of the styrene resin composition constituting the intermediate layer, The resin composition constituting the adhesive layer (AD layer) was 12 parts by mass. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 4)
As shown in Table 1, except that the stretching temperature in the lateral uniaxial direction was changed to 55 ° C., an attempt was made to produce a heat-shrinkable laminated film in the same manner as in Example 1, but breakage occurred during film stretching, A heat-shrinkable laminated film stretched at a predetermined magnification could not be obtained.

(Comparative Example 5)
As shown in Table 1, except that the stretching temperature in the lateral uniaxial direction was changed to 125 ° C., an attempt was made to produce a heat-shrinkable laminated film in the same manner as in Example 1, but the film drooped under its own weight during stretching. The desired heat-shrinkable laminated film could not be obtained.

(Comparative Example 6)
As shown in Table 1, except that AD1 used for the adhesive layer (AD layer) was changed to SBS (styrene content 87 mass%, Tg 36 ° C.) (hereinafter abbreviated as “AD2”), it was the same as Example 1. A heat-shrinkable laminated film and a heat-shrinkable laminated film after regeneration addition were obtained. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 7)
As shown in Table 1, in Example 1, except that the mass ratio of the mixed resin composition composed of SBS1 and SBS2 used for the intermediate layer (M layer) was changed to SBS1: 20 mass% and SBS2: 80 mass%. A heat-shrinkable laminated film was obtained in the same manner as in Example 1. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 8)
As shown in Table 1, in Example 1, AD1 used for the adhesive layer (AD layer) was changed to EAA (Novatech A500W manufactured by Japan Polytechnics, AA content 20 wt%) (hereinafter abbreviated as “AD3”). Except for the above, a heat-shrinkable laminated film was obtained in the same manner as in Example 1. The results of evaluating the obtained film are shown in Table 2.

From Table 1, the films of Examples 1, 2, 3 and 4 constituted by layers within the range defined by the present invention are all in shrink finish, peel strength, transparency at the time of regeneration addition, and evaluation of popping out of contents. Was also superior to the films of Comparative Examples 1-8.
On the other hand, with the film of the comparative example 1 comprised only with the polyester-type resin composition, the film of the comparative example 2 which extended | stretched outside the range prescribed | regulated by this invention, and the lamination | stacking ratio outside the range prescribed | regulated by this invention All of the films of Comparative Example 3 thus configured had high shrinkage stress and were inferior in shrink finish. Moreover, in the films of Comparative Examples 4 and 5 which were stretched at a temperature outside the range defined in the present invention, it was difficult to stretch at a desired magnification. Furthermore, the films of Comparative Examples 6 and 8 using a resin other than the resin composition defined in the present invention for the adhesive layer (AD layer) do not provide sufficient seal strength, and the transparency of the film after the regeneration addition is high. Remarkably worsened.
From this, the film of the present invention has good film stiffness, natural shrinkage, transparency at the time of regeneration addition, and delamination of the film, shrinkage stress is suppressed, shrink wrapping, shrink tying wrapping, shrink labels, etc. It can be seen that this is a heat-shrinkable laminated film suitable for the above applications.

  The film of the present invention has good transparency at the time of film addition and regeneration, and is used in applications such as shrink wrapping, shrink tying wrapping, and shrink labels, in which natural shrinkage, delamination, and shrinkage stress of the film are suppressed. Since it is a suitable heat-shrinkable laminated film, it can be used as a molded product used in bottles (blow bottles), trays, lunch boxes, prepared food containers, dairy products containers and the like. In particular, since it can be returned to the intermediate layer in the manufacturing process, it is very advantageous in terms of cost.

Claims (12)

A laminated film having a surface layer (S layer), an intermediate layer (M layer), and an adhesive layer (AD layer), each layer comprising a resin composition having the following components as main components and orthogonal to the film main shrinkage direction The tensile elastic modulus measured in accordance with JIS K7127 in the direction of the film is 1200 MPa or more, and the maximum shrinkage stress in the main film shrinkage direction when immersed in silicon oil at 90 ° C. for 10 seconds is 5 MPa or more and 8 MPa or less. A heat-shrinkable laminated film, characterized in that
Surface layer (S layer): Aromatic polyester resin composition containing polyvalent carboxylic acid residue and polyhydric alcohol residue Intermediate layer (M layer): Copolymerization of styrene hydrocarbon and conjugated diene hydrocarbon Styrenic resin composition comprising polymer Adhesive layer (AD layer): containing a copolymer of styrene hydrocarbon and conjugated diene hydrocarbon or a hydrogenated derivative thereof, and styrene in the copolymer or hydrogenated derivative Resin composition having a content of hydrocarbon based on 5% by mass or more and 40% by mass or less It has a surface layer (S layer), an intermediate layer (M layer) and an adhesive layer (AD layer), and each layer is composed of a resin composition containing the following components as main components, and at least 60 ° C. and 120 ° C. A laminated film stretched in the uniaxial direction by 2 times or more and 7 times or less, the tensile elastic modulus measured according to JIS K7127 in the direction perpendicular to the main shrinkage direction of the film is 1200 MPa or more, and 90 A heat-shrinkable laminated film having a maximum shrinkage stress in the main shrinkage direction of 5 MPa or more and 8 MPa or less when immersed in silicon oil at 10 ° C. for 10 seconds.
Surface layer (S layer): polyvalent carboxylic acid residue and an aromatic polyester resin composition intermediate layer containing a polyhydric alcohol residue (M layer): a block of a styrene series hydrocarbon and a conjugated diene hydrocarbon Styrenic resin composition adhesive layer (AD layer) comprising a copolymer: consisting of a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon or a hydrogenated derivative thereof, in the copolymer or hydrogenated derivative Resin composition having a styrene-based hydrocarbon content of 5% by mass or more and 40% by mass or less The said intermediate | middle layer (M layer) contains 1 to 100 mass parts of resin which comprises the said surface layer (S layer) with respect to 100 mass parts of resin which comprises this intermediate | middle layer (M layer). 2. A heat-shrinkable laminated film according to 2. The said intermediate | middle layer (M layer) contains 1 to 30 mass parts of resin which comprises the said adhesive layer (AD layer) with respect to 100 mass parts of resin which comprises this intermediate | middle layer (M layer). 4. The heat-shrinkable laminated film according to any one of 3. The aromatic polyester resin composition constituting the surface layer (S layer) comprises an aromatic dicarboxylic acid residue and a diol residue, and 15 mol% to 50 mol% of 1, The heat-shrinkable laminated film according to any one of claims 1 to 4, which is a resin composition mainly composed of an amorphous polyethylene terephthalate-based resin containing a 4-cyclohexanedimethanol residue. The heat-shrinkable laminated film according to any one of claims 1 to 5 , wherein a glass transition point of a copolymer or a hydrogenated derivative thereof constituting the adhesive layer (AD layer) is 20 ° C or lower. The heat-shrinkable laminated film according to any one of claims 1 to 6 , wherein a thickness ratio of the surface layer (S layer) to the thickness of the entire film is 10% or more and 70% or less. The heat-shrinkable laminated film according to any one of claims 1 to 7 , wherein a haze value measured in accordance with JIS K7105 is 10% or less. The thermal contraction rate in the main contraction direction when immersed in warm water at 70 ° C. for 10 seconds is 10% or more and 40% or less, and the thermal contraction rate in the main contraction direction when immersed in warm water at 80 ° C. for 10 seconds is 30% or more and 70%. The heat-shrinkable laminated film according to any one of claims 1 to 8 , wherein the heat-shrinkable laminated film is at most%. Molded article using as a substrate a heat-shrinkable laminate film according to any one of claims 1 to 9. Heat-shrinkable label employing the heat-shrinkable laminate film according as the substrate in any one of claims 1 to 9. A container equipped with the molded product according to claim 10 or the heat-shrinkable label according to claim 11 .