JP4504890B2 - Heat-shrinkable laminated film, molded product using the film, heat-shrinkable label, and container equipped with these - Google Patents

Description

  The present invention relates to a heat-shrinkable laminated film, a molded article using the film, a heat-shrinkable label, and a container equipped with the same. More specifically, the present invention is a shrink wrap that has excellent film stiffness (rigidity at room temperature), heat shrinkage characteristics, small spontaneous shrinkage, sufficient delamination, and excellent transparency when added to regeneration. The present invention relates to a heat-shrinkable laminated film suitable for applications such as shrink-bound packaging and shrinkage labels, as well as molded articles using the film, heat-shrinkable labels, and containers equipped with these.

  Currently, soft drinks such as juice and alcoholic drinks such as beer are sold in a state of being filled in containers such as bottles and plastic bottles. 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 often attached. As a material for this heat-shrinkable label, polyvinyl chloride, polyester, polystyrene or the like is usually used.

  Polyvinyl chloride (“PVC”) heat-shrinkable films have good shrinkage finish and natural shrinkage resistance (ie, low natural shrinkage), and have been widely used as heat-shrinkable labels. It was. However, since it can cause generation of harmful gases such as hydrogen chloride and dioxin at the time of incineration after use, development of a heat shrinkable film using a material that replaces the PVC system in recent years has been performed. On the other hand, a heat shrinkable film having a high shrinkage appearance in a relatively short time and at a relatively low temperature and a small natural shrinkage rate for PET bottle labeling and the like for which demand is expected to increase in the future. Is required. The reason for this is the need for low temperatures in the labeling process of shrink films that are installed in recent PET bottles. That is, at present, the method of shrinking and labeling the heat-shrinkable film using steam shrinker has become the mainstream, but in order to avoid aseptic filling and quality deterioration due to temperature rise of the contents, the shrinking process can be performed as much as possible. It is desirable to carry out at a low temperature. For this reason, the current shrink film industry is developing heat-shrinkable films that start shrinking at the lowest possible temperature in the steam shrinker during labeling and that have excellent shrink finish characteristics after passing through the steam shrinker. It has been broken.

  For the above applications, polyester-based heat-shrinkable films that are rigid at room temperature, have low-temperature shrinkability, and have very good natural shrinkage are mainly used. However, the polyester-based heat-shrinkable film has a problem that shrinkage spots and wrinkles are easily generated during heat-shrinkage as compared with the PVC-based heat-shrinkable film.

  On the other hand, in order to overcome the problems of the PVC-based and polyester-based heat-shrinkable films, polystyrene-based heat-shrinkable films mainly composed of a styrene-butadiene block copolymer (SBS) have been proposed and used. This polystyrene-based heat-shrinkable film has the advantage of good shrinkage finish compared to PVC-based and polyester-based heat-shrinkable films, but has problems such as weakness and poor natural shrinkage. there were. Therefore, development of a styrene-based heat-shrinkable film that can solve these problems has been performed.

  As a means to solve the above problems, film stretching and heat shrinkage by stretching a mixed resin of vinyl aromatic hydrocarbon-conjugated diene copolymer having specific dynamic viscoelastic behavior (tan δ) and polystyrene resin. Improvement of characteristics and suppression of spontaneous shrinkage are attempted (see Patent Document 1). However, it is not fully satisfactory in terms of film stiffness, heat shrinkage, and natural shrinkage, and is not as good as polyester film in these physical properties.

  As a means for improving this, a shrink label comprising a base film 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. It has been reported (see Patent Document 2). However, this shrink label has insufficient adhesion between layers, and there is a problem that peeling is likely to occur at the polystyrene resin layer-polyester resin interface during secondary processing (film bagging, printing, bottle mounting, etc.). there were.

Furthermore, in order to improve interlayer adhesion, block copolymer of styrene hydrocarbon and conjugated diene derivative in the inner layer, copolymer polyester in both outer layers, ethylene-vinyl acetate copolymer in the adhesive layer, ethylene-unsaturated A film using a carboxylic acid copolymer or the like (see Patent Document 3) or a resin sheet mainly composed of a polyester resin sheet and a styrene-based hydrocarbon-unsaturated carboxylic acid ester copolymer is bonded with a solvent or a solvent-type adhesive. A film (Patent Document 4) formed after being stretched has been reported. However, since the film described in Patent Document 3 has poor compatibility between the resin used for the inner layer and the resin used for the adhesive layer, a recycled resin generated from trimming loss or the like of the ears of the film is added (hereinafter, referred to as “film”). (Referred to as “regeneration addition”), the transparency of the entire film tends to decrease. In addition, the film described in Patent Document 4 also has a problem in that the productivity of the film is inferior because the transparency of the film is lowered and a solvent coating step is required when the regeneration addition is performed.
JP 11-269282 A JP 2002-351332 A Japanese Patent Publication No. 5-33896 JP-A-7-137212

  The present invention has been made in view of the above problems, and the object of the present invention is excellent in film waist (rigidity at room temperature) and heat shrinkage characteristics, small in natural shrinkage, and sufficiently suppressed 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 shrink labels, which are excellent in transparency upon regeneration addition.

  Another object of the present invention is to provide a molded article, a heat-shrinkable label, and a container using the film suitable for applications such as shrink wrapping, shrink-bound wrapping, and shrink labels.

As a result of intensive studies on the composition of the surface layer, the adhesive layer, and the intermediate layer forming the laminated film, the present inventor succeeded in obtaining a film that can solve the above-described problems of the prior art and completes the present invention. It came to.
That is, the object of the present invention is achieved by the following heat-shrinkable laminated film.
(1) A laminated film composed of at least three layers having a (II) layer between the (I) layer and the (III) layer, each layer comprising a resin mainly composed of the following components, A heat-shrinkable laminated film having a heat shrinkage rate of 20% or more in at least one direction when immersed in warm water for 10 seconds.
(I) Layer: Polyester resin (II) Layer: Styrenic thermoplastic resin having a styrene hydrocarbon content of 5% by mass to 50% by mass (III) Layer: Styrene monomer and (meth) acrylic acid A rubber-like elastic body is dispersed in a continuous phase of a copolymer comprising an ester monomer t, and the mixing ratio of the rubber-like elastic body and the copolymer is 1/99 to 20/80 by mass ratio. A rubber-like elastic-dispersed polystyrene resin (2) The polyester resin is composed of an aromatic dicarboxylic acid component and a diol component, and 1,4-cyclohexanedimethanol in the total diol component is 15 mol% or more and 50 mol%. The heat-shrinkable laminated film according to (1), which is a resin mainly composed of an amorphous polyethylene terephthalate-based resin contained below.
(3) The styrene monomer contained in the continuous phase of the rubber-like elastic-dispersed polystyrene resin is styrene, and the (meth) acrylic acid ester monomer is composed of two kinds of methyl methacrylate and butyl (meth) acrylate. The heat-shrinkable laminated film according to (1) or (2), which is a monomer.
(4) The rubber-like elastic material contained in the rubber-like elastic material-dispersed polystyrene resin is at least one selected from the group consisting of styrene-butadiene copolymers, styrene-isoprene copolymers, and hydrogenated derivatives thereof. The heat-shrinkable laminated film according to any one of (1) to (3).
(5) The heat-shrinkable laminated film according to any one of (1) to (4), wherein the tensile elastic modulus in the direction orthogonal to the main shrinkage direction measured in accordance with JIS K7127 is 1,400 MPa or more (6) The heat-shrinkable laminated film (7) according to any one of (1) to (5), wherein the thickness ratio of the (I) layer to the total film thickness is 10% to 70%. The recycled film is contained, the content of the film is 1% by mass or more and 50% by mass or less with respect to the total mass of the film, and the haze value of the film measured in accordance with JIS K7105 is 10%. The heat-shrinkable laminated film according to any one of (1) to (6) below.

Another object of the present invention is achieved by the following molded article, heat-shrinkable label, and container.
(8) A molded product using the heat-shrinkable laminated film according to any one of (1) to (7) as a base material.
(9) A heat-shrinkable label using the heat-shrinkable laminated film according to any one of (1) to (7) as a base material.
(10) A container equipped with the molded article according to (8) or the heat-shrinkable label according to (9).

  According to the present invention, waist (rigidity at normal temperature), shrinkage finish, transparency at the time of regeneration addition are excellent, the film has little natural shrinkage (that is, excellent natural shrinkage resistance), and film delamination It is possible to provide a heat-shrinkable laminated film suitable for applications such as suppressed shrink packaging, shrink-bound packaging, and shrink labels.

  Furthermore, according to the present invention, it is possible to provide a molded product, a heat-shrinkable label, and a container equipped with the molded product or label, which are stiff and have excellent shrinkage finish and transparency.

  Hereinafter, the heat-shrinkable laminated film, the molded product, the heat-shrinkable label, and the container equipped with the molded product or the heat-shrinkable label of the invention will be described in detail.

  In the present specification, “main component” is intended to allow other components to be included as long as the action and effect of the resin constituting each layer is not hindered. Furthermore, although this term does not restrict | limit a specific content rate, it is a component which occupies 70 mass% or more of the whole component of each layer, Preferably it is 80 mass% or more, More preferably, it is 90 mass% or more.

[Heat-shrinkable laminated film]
The heat-shrinkable laminated film of the present invention (hereinafter also referred to as “the film of the present invention”) has a (I) layer containing a polyester resin as a main component and a rubber-like elastic-dispersed polystyrene resin as a main component ( III) At least a three-layer structure formed by forming a layer (II) mainly composed of a styrene-based thermoplastic resin having a predetermined styrene-based hydrocarbon content for the purpose of providing adhesion between the layers. It is a film having.

<(I) layer>
The (I) layer of the film of the present invention is composed mainly of a polyester-based resin composed mainly of at least one thermoplastic polyester resin containing a polyvalent carboxylic acid component and a polyhydric alcohol component.

  Examples of the polyvalent carboxylic acid component used in the (I) layer include terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2,5-dichloroterephthalic acid, 2-methylterephthalic acid, and 4,4-stilbene dicarboxylic acid. 4,4-biphenyldicarboxylic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, bisbenzoic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4-diphenyl ether Dicarboxylic acid, 4,4-diphenoxyethanedicarboxylic acid, 5-Na sulfoisophthalic acid, aromatic dicarboxylic acid such as ethylene-bis-p-benzoic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, 1, 3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid It includes aliphatic dicarboxylic acid component. These polyvalent carboxylic acid components can be used alone or in combination of two or more.

  Examples of the polyhydric alcohol component used in the (I) 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- Hydroxyethyl ether And the like. These polyhydric alcohol components can be used individually by 1 type or in mixture of 2 or more types.

  Specific examples of the thermoplastic polyester resin composed of the polyvalent carboxylic acid component and the polyhydric alcohol component include, for example, polyethylene terephthalate resin, polypropylene terephthalate resin, polybutylene terephthalate resin, polyethylene isophthalate resin, polyethylene naphthalate resin. , Polybutylene naphthalate resin, polyethylene terephthalate-isophthalate copolymer resin, amorphous polyethylene terephthalate resin containing a 1,4-cyclohexanedimethanol component in a polyhydric alcohol component, and the like. 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 contained in the amorphous polyethylene terephthalate resin is 15 mol% or more, preferably 20 mol% or more in the total diol component, and the upper limit is 50 mol%. Hereinafter, it is preferably in the range of 40 mol%, more preferably in the range of 20 mol% or more and 40 mol% or less. If the content of the 1,4-cyclohexanedimethanol component is 15 mol% or more, it is possible to suppress deterioration in printability due to crystallization and embrittlement over time, and if it is 50 mol% or less, extrusion melting. At the same time, an appropriate viscosity can be maintained and 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 used in the (I) layer is 30,000 or more, preferably 35,000 or more, more preferably 40,000 or more, and the upper limit is 80,000 or less, preferably It is 75,000 or less, More preferably, it is 70,000 or less. 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 (I) layer is 0.5 dl / g or more, preferably 0.6 dl / g or more, more preferably 0.7 dl / g or more, and 1.5 dl. / G or less, preferably 1.2 dl / g or less, more preferably 1.0 dl / g or less. If the intrinsic viscosity (IV) of the polyester-based resin is 0.5 dl / g or more, a decrease in film strength characteristics can be suppressed. On the other hand, if the intrinsic viscosity (IV) of the polyester-based resin 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, "PETG6763" (made by Eastman Chemical), "SKYREEN PETG" (made by SK Chemical), etc. are mentioned, for example.

  In the (I) layer of the film of the present invention, it is also useful to mix a crystalline polyester resin typified by polybutylene terephthalate or polybutylene terephthalate copolymerized with polyether. 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 will be difficult to satisfy the required characteristics sufficiently as a heat shrinkable film. Therefore, it may be preferable to impart appropriate crystallinity depending on the application.

  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. In the initial stage of the stretching process, when the heated film is partially viewed, it may show a non-uniform temperature distribution. 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, but the stretching stress increases due to orientation crystallization, so that the non-stretched 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 in the (I) layer, it is 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass with respect to 100 parts by mass of the polyester resin constituting the (I) layer. The amount of the crystalline polyester resin is 30 parts by mass or less, preferably 25 parts by mass or less, and more preferably 20 parts by mass or less. If the content of the crystalline polyester-based resin is 1 part by mass or more, appropriate crystallinity can be imparted to the film, and the film shrinks gradually, so that good shrinkage finish can be expected. Moreover, if the content rate of crystalline polyester-type resin is 30 mass parts or less, the elasticity and shrinkage | contraction characteristic of a film can be maintained, and it can use suitably as a heat shrink film, without inhibiting printability and solvent sealing property.

<(III) layer>
The (III) layer in the film of the present invention comprises a rubber-like elastic material-dispersed polystyrene resin in which a rubber-like elastic material is dispersed in a continuous phase of a copolymer comprising a styrene monomer and a (meth) acrylate monomer. Consists of.

  Here, the styrenic monomer in the continuous phase is composed of structural units represented by the following general formula (A).

In the formula, R ₁ is hydrogen or a methyl group, and R ₂ is hydrogen or an alkyl group having 1 to 5 carbon atoms.

  Examples of the styrenic monomer 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); Polyalkoxystyrenes such as poly (p-, m- or o-methoxystyrene), poly (o-, m- or p-ethoxystyrene); poly (o-, m-, or p-carboxymethylstyrene) ); Polyalkyl ether styrene such as poly (p-vinylbenzylpropyl ether); polyalkylsilyl styrene such as poly (p-trimethylsilyl styrene); and various monomers such as polyvinyl benzyl dimethoxy phosphide Is mentioned. A styrene-type monomer may be comprised by these single or 2 or more types.

  On the other hand, the (meth) acrylic acid ester monomer in the continuous phase is composed of structural units represented by the following general formula (B).

In the formula, R ₃ is hydrogen or a methyl group, and R ₄ is hydrogen or an alkyl group having 1 to 20 carbon atoms and 0 or 1 oxygen.

  Examples of the (meth) acrylic acid ester monomers include methyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, and 2-ethylhexyl (meth). Acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, Various monomers such as tetrahydrofurfuryl (meth) acrylate are exemplified. Here, (meth) acrylate refers to acrylate and / or methacrylate. The acrylate monomer may be composed of these alone or in combination of two or more.

  The ratio of the styrenic monomer and the (meth) acrylic acid ester monomer is selected as one factor so that the refractive index of the continuous phase is close to the refractive index of the selected rubber-like elastic dispersed particles. Usually, the mass ratio is appropriately adjusted in the range of 25/75 to 90/10, preferably in the range of 30/70 to 85/15, taking other characteristics into consideration.

  The styrenic monomer most preferably used in the present invention is styrene (hereinafter referred to as “ST”), while the (meth) acrylic acid ester monomer is methyl methacrylate (hereinafter referred to as “MMA”) and butyl. Two types of monomers composed of acrylate (hereinafter referred to as “BA”). The reason for this is that the reactivity at the time of polymerization is high, and copolymerization with high randomness is possible. By combining the three, the characteristics such as the refractive index and the Bikatto softening point can be easily controlled. This is because the raw material is industrially produced so much that it is excellent in cost as a raw material.

  These copolymerization ratios are, by mass ratio, ST / MMA / BA = 30 to 90/10 to 70/1 to 20, preferably 35 to 85/15 to 65/1 to 18, and more preferably 40 to 80 / It adjusts in the range of 20-60 / 1-15. If the ST copolymerization ratio is out of the above range, the stiffness and transparency of the film may be lowered, and the impact resistance may be lowered. Further, if the copolymerization ratio of MMA is out of the above range, it becomes difficult to set the refractive index of the continuous phase to be close to the refractive index of the rubber-like elastic dispersed particles, the transparency is lowered, and the heat shrinkability. The clear display effect as a film may be reduced. On the other hand, if the copolymerization ratio of BA is out of the above range, there are cases where the natural shrinkage of the film increases and the shrinkage characteristics deteriorate.

  (III) The rubber-like elastic material contained in the rubber-like elastic-dispersed polystyrene resin constituting the layer is a general term for polymer compounds that exhibit rubber properties at room temperature. In view of the refractive index, those containing styrene are desirable. Specific examples of the rubber-like elastic body include, for example, styrene-butadiene copolymers (for example, SBR and SBS), styrene-isoprene copolymers (for example, SIR and SIS), and hydrogenated derivatives thereof. Of these, a styrene-butadiene copolymer is preferred. Considering the physical properties and refractive index of rubber, the content of styrene in the rubber elastic body is 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, and 60% by mass or less, preferably 55%. It is desirable that it is in the range of not more than mass%, more preferably not more than 50 mass%.

  The mixing ratio of the rubber-like elastic body, the copolymer comprising the styrene monomer and the (meth) acrylic acid ester monomer is 1/99 to 20/80, preferably 3/97 to 15/85 in mass ratio. It is desirable to do. If the mixing ratio of the rubber-like elastic body is less than 1% by mass, the resulting heat-shrinkable film may have low impact resistance (breaking resistance). The rigidity is lowered, and there is a possibility that, for example, in the process of covering a bottle or the like as a shrinkable label, it is impossible to cover a predetermined position.

The particle diameter of the dispersed particles formed by the rubber-like elastic body in the (III) layer is 0.1 μm or more, preferably 0.2 μm or more, more preferably 0.3 μm or more, and 1.2 μm or less, preferably Is preferably 1.1 μm or less, more preferably 1.0 μm or less. If the dispersed particle size is less than 0.1 μm, the effect of improving the impact resistance of the heat-shrinkable film may not be sufficiently exhibited. On the other hand, when the dispersed particle diameter exceeds 1.2 μm, the impact resistance is sufficiently improved, but the transparency required for a heat shrinkable film may be difficult to obtain.
The particle diameter of the dispersed particles of the rubber-like elastic body is a number average particle diameter obtained from a photograph obtained by photographing a sample prepared from raw material pellets by an ultrathin section method using a transmission electron microscope.

  The rubber-like elastic-dispersed polystyrene resin has a weight (mass) 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. Preferably it is 300,000 or less. If the weight (mass) average molecular weight (Mw) of the rubber-like elastic-dispersed polystyrene resin is 100,000 or more, it is preferable that there is no defect that causes deterioration of the film. On the other hand, if the weight (mass) average molecular weight is 500,000 or less, it is not necessary to adjust the flow characteristics and there are no defects such as deterioration of extrudability, which is preferable.

  The measured value of melt flow rate (MFR) of the rubber-like elastic-dispersed polystyrene resin (measurement conditions: temperature 200 ° C., load 49 N) is 1 g / 10 min or more, preferably 2 g / 10 min or more, and 20 g / 10 It is desirable that it is not more than minutes, preferably not more than 18 g / 10 minutes, more preferably not more than 15 g / 10 minutes. If MFR is 1 g / 10 min or more, an appropriate fluid viscosity can be obtained at the time of extrusion molding, and productivity can be maintained or improved. Further, if the MFR is 20 g / 10 min or less, an appropriate resin cohesive force can be obtained, so that a good film strength and elongation can be obtained, and the film can be made difficult to become brittle.

  The (III) layer further contains a tackifier resin and / or a plasticizer in an amount of 1 to 20 parts by weight, preferably 1 to 18 parts by weight, based on 100 parts by weight of the rubber-like elastic-dispersed polystyrene resin. More preferably, it can be contained in the range of 1 part by mass or more and 15 parts by mass or less. By adding a tackifier resin and / or a plasticizer to the (III) layer, the following two effects can be brought about.

  One is that these additives plasticize the rubber-like elastic dispersion particles to facilitate deformation, and prevent the dispersion particles from protruding onto the film surface during the film extrusion / stretching process. It is a function to maintain sex. The other is a function of lowering the bicat softening temperature of the resin and imparting shrinkage properties together with a long-chain alkyl (meth) acrylate monomer such as BA copolymerized in the continuous phase. The tackifying resin and the plasticizer have more or less the functions of both, but if the effects are purposely distinguished, the tackifying resin has a strong function of the former, and the plasticizer has a strong function of the latter.

Examples of tackifying resins include a) rosin such as rosin, modified rosin, polymerized rosin, rosin glycerin ester, etc., b) α-pinene polymer, β-pinene polymer, dipentene polymer, terpene-phenol copolymer, α-pinene- Polyterpene resins such as phenol copolymers, c) copolymers of cyclopentadiene-isoprene- (1,3-pentadiene)-(1-pentene), copolymers of (2-pentene) -dicyclopentadiene, 1 , 3-pentadiene mainly of a resin such as C ₅ petroleum resins, d) indene - styrene - C ₈ -C ₁₀ systems tar petroleum resins such as methyl indene -α-methyl styrene copolymer, e) dicyclopentadiene mainly DCPD petroleum resins such as these resins, and partially hydrogenated products and fully hydrogenated products a) to e) are preferably used. Examples of the plasticizer include a) aliphatic ester systems such as dioctyl sebacate, dioctyl adipate, diisononyl adipate, diisodecyl adipate, and b) aromatic ester systems such as diethyl phthalate, dibutyl phthalate, dioctyl phthalate, diisodecyl phthalate, and dicyclohexyl phthalate. c) aliphatic polyesters such as poly (1,4-ethylene adipate) and poly (1,4-ethylene succinate), d) phosphate esters such as tricresyl phosphate and triphenyl phosphate, and the like. It is done.

  Examples of commercially available rubber-like elastic-dispersed polystyrene resins include “Clear Pact” (Dainippon Ink & Chemicals) and “SX Series” (PS Japan).

<(II) layer>
The (II) layer in the present invention is composed mainly of a styrene thermoplastic resin having a styrene hydrocarbon content of 5% by mass or more and 50% by mass or less.

  Here, the styrene thermoplastic resin refers to a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon or a hydrogenated derivative thereof. As the styrenic hydrocarbon, styrene is preferably used, 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, which may be unhydrogenated or hydrogenated. You may use these individually or in mixture of 2 or more types.

  It is important that the content of styrenic hydrocarbon in the styrenic thermoplastic resin is 5% by mass or more of the total amount of the copolymer, more preferably 7% by mass or more, and further preferably 10% by mass or more. is there. Moreover, it is important that the upper limit of the content rate of a styrene-type hydrocarbon is 50 mass%, Preferably it is 40 mass%, More preferably, it is 35 mass%. If the content of styrenic hydrocarbon is 5% by mass or more, good when the recycled film of the present invention is returned to the (I) layer and / or (III) layer (preferably (III) layer) Compatibility is obtained, and the cloudiness of the film can be suppressed. On the other hand, if the content of the styrene-based hydrocarbon is 50% by mass or less, the stress of the (I) layer and the (III) layer is reduced when stress is applied to the film without reducing the flexibility of the (II) layer. Since the buffering action against the stress generated in between works, delamination can be suppressed.

  As the styrene-based thermoplastic resin, a hydrogenated derivative of a styrene-conjugated diene random copolymer can be preferably used. The detailed contents of the hydrogenated derivative of the styrene-conjugated diene random copolymer and the production method thereof are disclosed in JP-A-2-15843, JP-A-2-305814 and JP-A-3-72512. ing.

  Commercially available products of the copolymer used in the (II) layer include a styrene-butadiene block copolymer elastomer (Asahi Kasei Chemicals Co., Ltd. trade name “Tufprene”), a hydrogenated derivative of a styrene-butadiene block copolymer (Asahi Kasei). Chemicals Co., Ltd. trade name “Tuftec H”, Shell Japan Co., Ltd. trade name “Clayton G”), hydrogenated derivative of styrene-butadiene random copolymer (JSR Co., Ltd. trade name “Dynalon”), styrene-isoprene Examples include hydrogenated derivatives of block copolymers (Kuraray brand name "Septon"), styrene-vinylisoprene block copolymer elastomers (Kuraray brand name "Hibler"), etc. , Or a mixture of two or more.

  Moreover, the said styrene-type thermoplastic resin can further improve interlayer adhesiveness with the (I) layer which consists of a polyester-type resin by introduce | transducing a polar group. 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 styrene compound having a polar group 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. Specifically, Asahi Kasei Chemicals Co., Ltd. trade name “Tuftec M”, Daicel Chemical Co., Ltd. trade name “Epofriend”, etc. are commercially available. These copolymers can be used alone or in admixture of two or more.

  In the present invention, in addition to the above-described components, any of the (I) layer, (II) layer, and (III) layer, or two or more layers, as long as the effects of the present invention are not significantly impaired, are molded. Recycled resin generated from trimming loss such as film ears, inorganic particles such as silica, talc, kaolin, calcium carbonate, titanium oxide for the purpose of improving and adjusting various physical properties of workability, productivity and heat shrinkable film Additives such as pigments such as carbon black, flame retardants, weathering stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, crosslinking agents, lubricants, nucleating agents, plasticizers, anti-aging agents can be added as appropriate .

<Layer structure of film>
If the film of this invention is a thing of the at least 3 layer structure which has (II) layer between (I) layer and (III) layer, a layer structure will not be specifically limited. Examples include (I) layer / (II) layer / (III) layer, (I) layer / (II) layer / (III) layer / (II) layer / (III) layer, (I) layer / (II ) Layer / (III) layer / (II) layer / (I) layer or (III) layer / (II) layer / (I) layer / (II) layer / (III) layer. Of these, the more effective laminated structure is (I) layer / (II) layer / (III) layer / (II) layer / (I) layer. By adopting this layer structure, the film object (rigidity at room temperature) and shrinkage characteristics, which are the object of the present invention, are excellent in natural shrinkage resistance, and the delamination is sufficiently suppressed. A heat-shrinkable laminated film excellent in transparency and suitable for applications such as shrink wrap, shrink-bound wrap and shrink labels can be obtained with good productivity and economy.

Next, a film having a five-layer structure of (I) layer / (II) layer / (III) layer / (II) layer / (I) layer, which is one of the preferred embodiments of the present invention, will be described.
The thickness ratio of each layer may be set in consideration of the above-described effects, and is not particularly limited. The thickness ratio of the (I) layer to the total film thickness is 10% or more, preferably 15% or more, more preferably 20%, and the upper limit of the thickness ratio is 70%, preferably 60%, more preferably 50%. It is. The thickness ratio of the intermediate layer (III) to the total film thickness is 20% or more, preferably 25% or more, more preferably 30% or more, and the upper limit is 80%, preferably 75%, more preferably 70. %. Further, the adhesive layer (II) layer has a function of 0.5 μm or more, preferably 0.75 μm or more, more preferably 1 μm or more, and the upper limit is desirably 5 μm, preferably 4 μm. If the thickness ratio of each layer is within the above range, the film shrinkage (excellent rigidity at room temperature), shrink finish, transparency during regeneration addition, excellent natural shrinkage, and delamination of the film is suppressed. In addition, a heat-shrinkable laminated film suitable for applications such as shrink-bound packaging and shrink labels can be obtained with a good balance.

  Although the total thickness of the film of the present invention is not particularly limited, it is preferably thinner from the viewpoints of transparency, shrinkage workability, raw material cost, and the like. Specifically, the total thickness of the stretched film is 80 μm or less, preferably 70 μm or less, more preferably 50 μm or less, and most preferably 40 μm or less. In addition, the lower limit of the total thickness of the film of the present invention is not particularly limited, but is preferably 20 μm in consideration of the handleability of the film.

<Physical and mechanical properties>
The waist (rigidity at room temperature) of the film of the present invention preferably has a tensile modulus of elasticity in the direction perpendicular to the main shrinkage direction of the film of 1,400 MPa or more, more preferably 1,500 MPa, or more, 1600 MPa or more. More preferably. Moreover, the upper limit of the tensile elasticity modulus of the heat shrinkable film used normally is about 3,000 MPa, preferably about 2,900 MPa, and more preferably about 2,800 MPa. If the tensile modulus in the direction perpendicular to the main shrinkage direction of the film is 1,400 MPa or more, the waist as a whole film (rigidity at room temperature) can be increased, especially when the thickness of the film is reduced, When a bag made of a plastic bottle or the like is covered with a labeling machine or the like, problems such as being obliquely covered or the yield being liable to decrease due to the film being folded back are less likely to occur. The said tensile elasticity modulus can be measured on 23 degreeC conditions according to JISK7127. As a means for adjusting the tensile elastic modulus of the film of the present invention, it is important that the resin composition of each layer is within the range specified by the present invention. At the same time, the thickness ratio of the (I) layer to the total film thickness is 10 % And the thickness of the (II) layer is preferably 5 μm or less.
In the present specification, the “main shrinkage direction” means the larger one of the longitudinal direction and the transverse direction in the stretching direction, and is, for example, a direction corresponding to the outer peripheral direction when the bottle is attached to the bottle.

  Next, it is important that the film of the present invention has a thermal shrinkage rate of 20% or more in at least one direction when immersed in warm water at 80 ° C. for 10 seconds.

  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 rate required for a heat-shrinkable film applied to the use of shrinkage labels for PET bottles varies depending on the shape, but is generally about 20% 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. The heat-shrinkable film needs to sufficiently heat-shrink at a temperature as low as possible from the viewpoint of the influence of heat on the object to be coated. Furthermore, with the recent increase in the speed of the labeling process, there has been an increasing demand for shrinking quickly at a lower temperature. In consideration of such industrial productivity, a film having a heat shrinkage rate of 20% or more under the above conditions is preferable because it can be in close contact with the object to be coated within the shrinkage processing time. From these facts, the thermal shrinkage rate when immersed in warm water at 80 ° C. for 10 seconds is at least 20% or more, preferably 25% or more, more preferably 30% or more in the main shrinkage direction, The upper limit is 85%, preferably 80%, more preferably 75%.

  When the film of the present invention is used as a heat-shrinkable label, the heat shrinkage rate in the direction orthogonal to the main shrinkage direction is preferably 10% or less when immersed in warm water at 80 ° C. for 10 seconds, It is more preferably 5% or less, and further preferably 3% or less. If the film has a thermal shrinkage rate of 10% or less in the direction perpendicular to the main shrinkage direction, the dimension itself in the direction perpendicular to the main shrinkage direction after shrinkage may be shortened, or the printed pattern or character distortion after shrinkage may occur. In the case of a square bottle, it is preferable because troubles such as vertical sink are unlikely to occur.

  The film of the present invention has a thermal shrinkage rate of 5% or more, preferably 10% or more, more preferably 15% or more when immersed in warm water of 70 ° C. for 10 seconds, and the upper limit is 35% or less. , Preferably 30% or less, more preferably 25% or less. By setting the thermal shrinkage rate in the main shrinkage direction at 70 ° C. to 5% or more, shrinkage unevenness that can occur locally when bottles are attached with steam shrinker is reduced, resulting in formation of wrinkles, avatars, etc. Can be suppressed. Further, by setting the upper limit of the heat shrinkage rate to 35% or less, extreme shrinkage at low temperatures can be suppressed, and for example, natural shrinkage can be kept small even in a high temperature environment such as summer. Further, the thermal shrinkage rate in the direction orthogonal to the main shrinkage direction of the film when immersed in warm water at 70 ° C. for 10 seconds is preferably 10% or less, more preferably 5% or less, and 3% or less. More preferably.

  In the present invention, the thermal shrinkage rate in the main shrinkage direction is 40% to 85% at 80 ° C, 5% to 35% at 70 ° C, and the thermal shrinkage rate in the orthogonal direction is 10% at 80 ° C. It is important that the resin composition of each layer is within the range specified in the present invention. In particular, the thickness ratio of the (I) layer to the total film thickness is 10% or more, and the thickness of the (II) layer is 5 μm or less. It is preferable to control the stretching ratio in the range of 2 to 10 times and the stretching temperature in the range of 60 to 130 ° C.

  The natural shrinkage ratio of the film of the present invention is preferably as small as possible. Generally, the natural shrinkage ratio of a heat-shrinkable film is, for example, 3.0% after 30 days of storage at 30 ° C. and 50% RH. It is important that it is less than 2.0%, preferably 2.0% or less, more preferably 1.5% or less. If the natural shrinkage rate under the above conditions is less than 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 problems are hardly caused in practice. As a means for adjusting the natural shrinkage rate of the film, it is important that the resin composition of each layer is within the range specified in the present invention. In particular, the thickness ratio of the (I) layer to the total film thickness is 10% or more. It is preferable that

  For example, when the film of the present invention has a thickness of 50 μm measured according to JIS K7105, the haze value is preferably 10% or less, more preferably 7% or less, and 5%. More preferably, it is as follows. 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 this invention is 1 mass% or more and 50 mass% or less with respect to the mass of the whole film in (I) layer and / or (III) layer (preferably (III) layer), for example, Preferably it is 1 mass. % To 30% by mass, more preferably 1% by mass to 25% by mass, and most preferably 1% by mass to 20% by mass of a recycled film, even when a recycled film is regenerated and added, JIS K7105 The haze value when measured according to the above can be 10% or less, preferably 7% or less, more preferably 5% or less. If the haze value after regeneration addition is 10% or less, good transparency can be maintained even during reuse. Thereby, the film of this invention can recycle | reuse the film both ends (ear | edge) etc. which generate | occur | produced in the manufacturing process of a film as a raw material, and can maintain the transparency in the obtained film favorably. The haze value of the film after the regeneration addition can be adjusted by increasing or decreasing the addition amount at the time of regeneration addition. For example, the haze value of the film can be reduced to 7% or less by adjusting the amount of the ear film added to the (III) layer to 40% by mass or less.

  The impact resistance of the film of the present invention is evaluated by the tensile elongation at break, and in a tensile test under the environment of −10 ° C., particularly in the label application, the elongation is 150% or more in the film take-off (flow) direction (MD), Preferably it is 200% or more, more preferably 250% or more. If the tensile elongation at break in an environment of 0 ° C. is 100% or more, such a problem that the film is not easily broken at the time of printing and bag making is preferable. In addition, even when the tension applied to the film increases as the speed of processes such as printing and bag making increases, it is more preferable that the tensile elongation at break is 200% or more, which makes it difficult to break. As a means for adjusting the tensile elongation at break of the film, it is important that the resin composition of each layer is within the range specified by the present invention. In particular, the thickness ratio of the (I) layer to the total film thickness is 10%. The mass ratio of the styrene copolymer of the (III) layer is preferably 40% by mass or more.

  The delamination strength (seal strength) of the film of the present invention was measured using the measurement method described in the examples described later (23 ° C., 50% RH environment, T-type peeling method in the TD direction at a test speed of 200 mm / min). 2N / 15 mm width or more, preferably 4 N / 15 mm width or more, more preferably 6 N / 15 mm width or more. The upper limit of the delamination strength is not particularly limited, but is preferably 15 N / 15 mm width or less from the viewpoint of solvent resistance on the film surface. Since the film of the present invention has a delamination strength of at least 3 N / 15 mm, troubles such as peeling of the seal portion during use do not occur. As a means for ensuring the delamination strength of the film, it is important that the resin composition of each layer is within the range specified in the present invention. In particular, the thickness of the (II) layer is 0.5 μm or more, III) It is important that the layer is composed of the resin defined in the present invention.

  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.

  In applications where the stretching ratio is contracted in two directions, such as for overlap, the vertical direction is 2 to 10 times, the horizontal direction is 2 to 10 times, preferably the vertical direction is 3 to 6 times, and the horizontal direction Is about 3 to 6 times. On the other hand, in applications such as heat-shrinkable labels that shrink mainly in one direction, the direction corresponding to the main shrinkage direction is 2 to 10 times, preferably 4 to 8 times, and the direction orthogonal to it is 1 or more times. It is desirable to select a magnification ratio that is not more than 2 times (1 time indicates that the film is not stretched), preferably 1.1 times or more and 1.5 times or less, substantially in the category of uniaxial stretching. . A biaxially stretched film stretched at a stretch ratio within the above range does not have an excessively large thermal shrinkage rate in the direction orthogonal to the main shrinkage direction.For example, when used as a shrinkage label, It is preferable because the so-called vertical shrinkage phenomenon, in which the film is thermally contracted in the vertical direction, can be suppressed.

  The stretching temperature needs to be changed depending on the glass transition temperature of the resin used and the properties required for the heat-shrinkable film, but is generally 60 ° C. or higher, preferably 70 ° C. or higher, and the upper limit is 130 ° C. or lower, preferably 110 ° C. It is controlled within the following range. The draw ratio is 1.5 times to 10 times, preferably 3 times to 7 times, preferably 3 times to 7 times in the main shrinkage direction, depending on the characteristics of the resin used, the stretching means, the stretching temperature, the target product form, etc. Preferably, it is appropriately determined in the direction of one axis or two axes within a range of 3 to 5 times. 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 a heat treatment or relaxation treatment at a temperature of about 50 ° C. or more and 100 ° C. or less for the purpose of reducing the natural shrinkage rate or improving the heat shrink property, if necessary, and then the molecular orientation is It cools rapidly within the time not to relax, and becomes a heat-shrinkable film.

  Further, the film of the present invention can be subjected to surface treatment such as corona treatment, printing, coating, vapor deposition, and surface treatment as needed, and further, bag making processing and perforation processing using various solvents and heat sealing.

  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. When printing is required in a cylindrical container such as a plastic bottle, first print the required image on one side of a wide flat film wound up on a roll, and then cut it to the required width while the print side is inside. The center seal (the shape of the seal portion is a so-called envelope) may be folded into a cylindrical shape. 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 ester-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. In the examples, the take-up (flow) direction of the laminated film is described as the “longitudinal” direction, and the perpendicular direction thereof is described as the “lateral” direction.

(1) Tensile modulus According to JIS K7127, the tensile modulus was measured in a direction (longitudinal direction) perpendicular to the main shrinkage direction of the film under the condition of a temperature of 23 ° C. The results of evaluation based on the following criteria are also shown.
A: Tensile elastic modulus is 1600 MPa or more. O: Tensile elastic modulus is 1400 MPa or more and less than 1600 MPa. X: Tensile elastic modulus is less than 1400 MPa.

(2) Thermal shrinkage rate The film was cut into a size of 100 mm in length and 100 mm in width, 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. As for the thermal shrinkage, the ratio of shrinkage to the original size before shrinkage was expressed in% in the horizontal direction.

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

(4) Low temperature tensile elongation at break Measured according to JIS K7127 in a direction (longitudinal direction) perpendicular to the main shrinkage direction of the film under conditions of a temperature of −10 ° C. and a test speed of 100 mm / min.

(5) Interlaminar peel strength At a position 10 mm from both lateral ends of the film, adhesion was made using a mixed solvent consisting of 90% by mass of THF and 10% by mass of n-hexane to produce a cylindrical label. The seal portion was cut to a width of 5 mm in a direction perpendicular to the circumference, and a peel test was performed using a tensile tester with a thermostatic bath (“201X” manufactured by Intesco Corporation). The delamination strength was evaluated by the following numerical values.
◎: Delamination strength is 6N / 15mm width or more ○: Delamination strength is 4N / 15mm width or more and less than 6N / 15mm width ×: Delamination strength is less than 2N / 15mm width

(6) Shrinkage Finishing A film printed with a grid of 10 mm intervals was cut into a size of MD 100 mm × TD 298 mm, and both ends of TD were overlapped by 10 mm and adhered with a tetrohydrofuran (THF) solvent to produce a cylindrical film. This cylindrical film was attached to a cylindrical PET bottle with a capacity of 1.5 L, and passed through the steam heating type 3.2 m (3 zones) shrink tunnel for 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 used for evaluation.
A: Shrinkage is sufficient and no wrinkles, avatars, or lattice distortions occur.
○: Shrinkage is sufficient, and wrinkles, avatars, and lattice distortions are very slight.
X: Shrinkage is sufficient, but wrinkles, avatars, and lattice distortions are remarkable.

(7) Haze value of the film after regeneration addition After the obtained film was pulverized using a pulverizer and regenerated pelletized, an amount corresponding to 30% by mass with respect to the total amount of the film was added to the intermediate layer (III) layer. Regeneration was added to obtain a regeneration addition film as in each Example. Using the obtained film having a thickness of 50 μm, the haze value was measured according to JIS K7105. The results of evaluation based on the following criteria are also shown.
◎: Haze value is less than 7% ○: Haze value is 7% or more and less than 10% ×: Haze value is 10% or more

Example 1
As shown in Table 1, as the resin constituting the (I) layer, Eastman Chemical Co., Ltd. polyester resin, trade name “coplyester 6663” (hereinafter abbreviated as “S1”) is used as the intermediate layer (III) layer as styrene. A rubber-like elastic-dispersed polystyrene resin (hereinafter referred to as “M1”) in which a copolymer consisting of 7% by mass of butadiene copolymer, 47% by mass of styrene, 38% by mass of methyl methacrylate, and 8% by mass of butyl acrylate became a continuous phase. And SIS product name “Clayton D1124” (styrene content 30% by mass) (hereinafter abbreviated as “AD1”) as an adhesive layer (II). Is put into a separate single screw extruder manufactured by Mitsubishi Heavy Industries, Ltd., and after melt mixing at a set temperature of 230 ° C., the thickness of each layer is (I) layer / (II Layer / (III) layer / (II) layer / (I) layer = 40 μm / 10 μm / 150 μm / 10 μm / 40 μm are co-extruded from a 3 type 5 layer die, taken up with a cast roll at 50 ° C., and cooled and solidified. An unstretched laminated sheet having a width of 300 mm and a thickness of 250 μm was obtained. Next, the film was stretched 5.0 times in the transverse uniaxial direction at a preheating temperature of 100 ° C. and a stretching temperature of 95 ° C. using a film tenter manufactured by Mitsubishi Heavy Industries, Ltd., and then rapidly cooled with cold air to form a heat-shrinkable laminated film having a thickness of 50 μm. Obtained. A film having all of the evaluation items as ◎ was evaluated as (◎), a film containing ◯ as (）), and a film having at least one × as (×). The evaluation results are shown in Table 2.

(Example 2)
As shown in Table 1, the resin constituting the (I) layer is a mixed resin of 90% by mass of S1 resin and 10% by mass of PBT resin manufactured by Mitsubishi Engineering Plastics, Inc., and the product name “Novaduran 5008”. Example 1 except that 3 parts by mass of a polyester plasticizer trade name “Polysizer W2610” (hereinafter abbreviated as “M2”) manufactured by Dainippon Ink & Chemicals, Inc. was added to 100 parts by mass of Similarly, a heat-shrinkable laminated film was obtained. The results of evaluating the obtained film are shown in Table 2.

(Example 3)
As shown in Table 1, the resin constituting the (II) layer is SEPS resin product name “Septon 2004” (styrene content 18%) (hereinafter abbreviated as “AD2”) manufactured by Kuraray Co., Ltd. The thickness of each layer of (1) layer / (II) layer / (III) layer / (II) layer / (I) layer = 20 μm / 5 μm / 200 μm / 5 μm / 20 μm A shrinkable laminated film was obtained. The results of evaluating the obtained film are shown in Table 2.

Example 4
As shown in Table 1, 2 parts by mass of M2 was added to the (III) layer, and the thickness of each layer in the unstretched laminated sheet (I) layer / (II) layer / (III) layer / (II) layer / ( I) Layer = 70 μm / 5 μm / 100 μm / 5 μm / 70 μm A heat-shrinkable laminated film was obtained in the same manner as in Example 1 except that the layer was changed. The results of evaluating the obtained film are shown in Table 2.

(Example 5)
As shown in Table 1, except that the resin constituting the (II) layer was changed to the Kuraray SEBS resin trade name “Clayton G1657” (styrene content 13%) (hereinafter abbreviated as “AD3”). A heat-shrinkable laminated film was obtained in the same manner as in Example 4. The results of evaluating the obtained film are shown in Table 2.

(Example 6)
As shown in Table 1, the resin constituting the (II) layer was SEP resin manufactured by Kuraray Co., Ltd., trade name “Septon 1001” (styrene content 35%) (hereinafter abbreviated as “AD4”). A heat-shrinkable laminated film was obtained in the same manner as in Example 4. The results of evaluating the obtained film are shown in Table 2.

(Example 7)
As shown in Table 1, the resin constituting the (III) layer is a continuous copolymer comprising 10% by mass of a styrene-butadiene copolymer, 47% by mass of styrene, 32% by mass of methyl methacrylate, and 11% by mass of butyl acrylate. A heat-shrinkable laminated film was obtained in the same manner as in Example 1 except that the rubber-like elastic material-dispersed polystyrene resin (hereinafter abbreviated as “M3”) was used. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 1)
As shown in Table 1, the resins used in the (I) and (III) layers were put into separate single screw extruders manufactured by Mitsubishi Heavy Industries, Ltd., and after melt mixing at a set temperature of 230 ° C., the thickness of each layer was ( I) layer / (III) layer / (I) layer = co-extruded from a two-kind / three-layer die so as to be 40 μm / 170 μm / 40 μm, taken up with a cast roll at 50 ° C., cooled and solidified to have a width of 300 mm and a thickness of 250 μm An unstretched laminated sheet was obtained. Next, the film was stretched 5.0 times in the transverse uniaxial direction at a preheating temperature of 100 ° C. and a stretching temperature of 95 ° C. using a film tenter manufactured by Mitsubishi Heavy Industries, Ltd., and then rapidly cooled with cold air to form a heat-shrinkable laminated film having a thickness of 50 μm. Obtained. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 2)
As shown in Table 1, AD1 used in the (II) layer was changed to Kuraray Co., Ltd. SEPS copolymer trade name “Septon 2104” (styrene content 65%) (hereinafter abbreviated as “AD5”). A heat-shrinkable laminated film was obtained in the same manner as in Example 1 except that. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 3)
As shown in Table 1, AD1 used in the (II) layer was an ethylene-vinyl acetate copolymer trade name “Evaflex EV560” (VA content 14%) manufactured by Mitsui DuPont Polychemical Co., Ltd. (hereinafter referred to as “AD6”). A heat-shrinkable laminated film was obtained in the same manner as in Example 1 except that it was changed to “. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 4)
As shown in Table 1, the (III) layer does not contain a rubber component, and is a copolymer composed of 47% by mass of styrene, 38% by mass of methyl methacrylate, and 8% by mass of butyl acrylate (hereinafter abbreviated as “M4”). A heat-shrinkable laminated film was obtained in the same manner as in Example 1 except that. The results of evaluating the obtained film are shown in Table 2.

From Tables 1 and 2, the films of Examples 1 to 7 constituted by layers within the range defined by the present invention are waist (tensile elastic modulus of laminated film), heat shrinkage rate, natural shrinkage resistance, delamination strength, The transparency at the time of return was superior to those of Comparative Examples 1 to 4, and the shrinkage finish was equal to or higher than that of Comparative Examples 1 to 4.
On the other hand, when there is no adhesive layer (Comparative Example 1), when a styrene thermoplastic resin outside the range defined by the present invention is provided as the (II) layer (Comparative Example 2), sufficient delamination strength Was not obtained, and delamination occurred during the test. When the ethylene-vinyl acetate copolymer was used as the resin constituting the (II) layer (Comparative Example 3), the haze value after the regeneration addition decreased. Moreover, when the layer (III) was composed of a resin other than the present invention (Comparative Example 4), the film was found to have reduced fracture resistance.
As a result, the film of the present invention has excellent film stiffness (rigidity at room temperature), heat shrinkage characteristics, small spontaneous shrinkage, sufficient delamination, and excellent transparency when added to regeneration. It turns out that it is a heat-shrinkable laminated film suitable for uses such as packaging, shrink-bound packaging and heat-shrinkable labels.

  Since the film of the present invention is a heat-shrinkable film excellent in film stiffness, heat-shrinkage characteristics, natural shrinkage resistance, and transparency at the time of regeneration addition, various films such as various shrink wrapping, shrinkage binding, shrinkage labels, etc. Can be used for

Claims (10)

(I) A laminated film consisting of at least three layers having a (II) layer between a (III) layer and a (III) layer, wherein each layer is made of a resin having the following components as main components, and in warm water at 80 ° C. A heat-shrinkable laminated film having a heat shrinkage rate of 20% or more in at least one direction when immersed for 10 seconds.
(I) Layer: Polyester resin (II) Layer: Styrenic thermoplastic resin (III) layer having a styrene hydrocarbon content of 5% by mass or more and 50% by mass or less: Styrene monomer and (meth) acrylic acid A rubber-like elastic body is dispersed in a continuous phase of a copolymer composed of an ester-based monomer, and the mixing ratio of the rubber-like elastic body and the copolymer is 1/99 to 20/80 by mass ratio. A rubber-like elastic-dispersed polystyrene resin   The polyester-based resin is mainly composed of an amorphous polyethylene terephthalate-based resin comprising an aromatic dicarboxylic acid component and a diol component, wherein the total diol component contains 15 mol% to 50 mol% of 1,4-cyclohexanedimethanol. The heat-shrinkable laminated film according to claim 1, which is a resin as a component.   The styrene monomer contained in the continuous phase of the rubber-like elastic-dispersed polystyrene resin is styrene, and the (meth) acrylic acid ester monomer is two kinds of monomers consisting of methyl methacrylate and butyl (meth) acrylate. The heat-shrinkable laminated film according to claim 1 or 2.   The rubber-like elastic body contained in the rubber-like elastic body-dispersed polystyrene resin is at least one selected from the group consisting of a styrene-butadiene copolymer, a styrene-isoprene copolymer, and hydrogenated derivatives thereof. The heat-shrinkable laminated film according to any one of 1 to 3.   The heat-shrinkable laminated film according to any one of claims 1 to 4, wherein a tensile elastic modulus in a direction orthogonal to the main shrinkage direction measured in accordance with JIS K7127 is 1,400 MPa or more.   The heat-shrinkable laminated film according to any one of claims 1 to 5, wherein a thickness ratio of the (I) layer to a thickness of the entire film is 10% or more and 70% or less.   The film in which the layer (III) contains the recycled film, and the content of the film is 1% by mass to 50% by mass with respect to the total mass of the film, and is measured in accordance with JIS K7105 The heat-shrinkable laminated film according to claim 1, which has a haze value of 10% or less.   A molded article using the heat-shrinkable laminated film according to claim 1 as a base material.   A heat-shrinkable label using the heat-shrinkable laminated film according to claim 1 as a base material.   A container equipped with the molded article according to claim 8 or the heat-shrinkable label according to claim 9.