JP4426488B2 - Heat-shrinkable laminated film and molded article and container using the film - Google Patents

Description

  The present invention relates to a heat-shrinkable laminated film, and a molded article and a container using the film. 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, and molded articles and containers using the film.

  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 (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, there is 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 has been reported (see Patent Document 3). However, since this film 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 film ear is added (hereinafter referred to as “regeneration addition”). ), The transparency of the entire film tends to decrease.
JP 11-269282 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 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 , The thickness ratio of the (I) layer to the thickness is 10% or more and 70% or less, and the thermal shrinkage rate when immersed in warm water at 80 ° C. for 10 seconds is 40% or more in at least one direction, and 30 ° C. A heat-shrinkable laminated film characterized by having a natural shrinkage rate of less than 3% when stored in a 50% RH atmosphere for 30 days.
(I) layer: polyester resin (II) layer: a copolymer of styrene hydrocarbon and conjugated diene hydrocarbon or a hydrogenated derivative thereof, and the content of styrene hydrocarbon is 5 mass% or more and 50 mass % Resin or less (III) layer: a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon and a styrene copolymer, the copolymer of the styrene hydrocarbon and the conjugated diene hydrocarbon (2) The layer (II) is a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon, or a hydrogen thereof, wherein the mass ratio of the coalescence to the styrene copolymer is 60/40 to 95/5. The heat-shrinkable laminated film according to (1), which contains 5 to 100 parts by mass of a tackifier resin with respect to 100 parts by mass of the additive derivative.
(3) The heat-shrinkable laminated film according to (2), wherein the tackifying resin is at least one selected from the group consisting of petroleum resins, terpene resins, and rosin resins.
(4) The polyester resin constituting the main component of the (I) layer is composed of an aromatic dicarboxylic acid component and a diol component, and 15 mol% or more and 50 mol of 1,4-cyclohexanedimethanol in all diol components. The heat-shrinkable laminated film according to any one of (1) to (3), which is a resin mainly composed of an amorphous polyethylene terephthalate-based resin containing at most%.
(5) Resin having a content of styrene hydrocarbon in the copolymer of styrene hydrocarbon and conjugated diene hydrocarbon constituting the main component of layer (III) of 55% by mass or more and 90% by mass or less The heat-shrinkable laminated film according to any one of (1) to (4).
(6) the direction of the tensile elastic modulus orthogonal to the film main shrinking direction measured in accordance with JIS K7127 is more than 1400 MPa (1) to heat-shrinkable laminated film according to any one of (5) (7) The heat-shrinkable laminated film according to any one of (1) to (6), wherein the thickness of the (II) layer is 0.5 μm or more and 5 μm or less.

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 product according to (8) or the heat-shrinkable label according to (9).

  According to the present invention, shrinkage packaging, shrinkage binding, which is excellent in waist (rigidity at normal temperature), shrinkage finish, transparency at the time of regeneration addition, little natural shrinkage of the film, and delamination of the film is suppressed. A heat-shrinkable laminated film suitable for uses such as packaging and shrinkage labels can be provided.

  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. In addition, the upper and lower limits of the numerical range in the present invention, even if slightly deviating from the numerical range specified by the present invention, as long as the same effect as in the numerical range is provided. Include within the equivalent range.

[Heat-shrinkable laminated film]
The heat-shrinkable laminated film of the present invention (hereinafter also referred to as “the film of the present invention”) comprises a (I) layer mainly composed of a polyester resin, and a co-weight of a styrene hydrocarbon and a conjugated diene hydrocarbon. Copolymers of styrene hydrocarbons and conjugated diene hydrocarbons or their copolymers for the purpose of providing adhesion between the layer (III) consisting mainly of a mixed resin of a polymer and a styrene copolymer. (II) layer which has a hydrogenated derivative as a main component is formed.

<(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 the upper limit is 1. 0.5 dl / g or less, preferably 1.2 dl / g or less, more preferably 0.7 to 1.0 dl / g. 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, "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 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 upper limit is 30 parts by mass or less, preferably 25 parts by mass or less, and more preferably 20 parts by mass or less of crystalline polyester resin. 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 of the film in the present invention is composed mainly of a mixed resin of a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon and a styrene copolymer.

  Examples of the styrenic hydrocarbon constituting the copolymer include polystyrene, poly (p-, m- or o-methylstyrene), poly (2,4-, 2,5-, 3,4- or 3, 5-dimethylstyrene), poly (alkylstyrene) such as poly (pt-butylstyrene); poly (o-, m- or p-chlorostyrene), poly (o-, m- or p-bromostyrene), poly Polyhalogenated styrene such as (o-, m- or p-fluorostyrene), poly (o-methyl-p-fluorostyrene); polyhalogenated such as poly (o-, m- or p-chloromethylstyrene) Substituted alkylstyrenes; polyalkoxystyrenes such as poly (p-, m- or o-methoxystyrene), poly (o-, m- or p-ethoxystyrene); poly (o-, m-, or p-carboxyme) Polycarboxyalkyl styrene such as styrene); polyalkyl ether styrene such as poly (p-vinylbenzylpropyl ether); polyalkylsilyl styrene such as poly (p-trimethylsilyl styrene); and polyvinylbenzyl dimethoxy phosphide. . The styrenic hydrocarbon may be composed of these alone or in combination of two or more.

  On the other hand, examples of the conjugated diene hydrocarbon constituting the copolymer include butadiene, isoprene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene and the like can be mentioned. The conjugated diene hydrocarbon may be composed of these singly or in combination.

  One copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon preferably used in the present invention is a styrene-butadiene copolymer in which the styrene hydrocarbon is styrene and the conjugated diene hydrocarbon is butadiene. It is a polymer (SBS). The styrene content of SBS is 55% by mass or more, preferably 60% by mass or more, and more preferably 65% by mass or more. The upper limit of the styrene content is 90% by mass, preferably 85% by mass, and more preferably 80% by mass. If the content of styrene is 55% by mass or more, the impact resistance effect can be exerted, and by setting the upper limit to 90% 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 aspect of a block copolymer, a random copolymer, and a copolymer having a tapered block structure. Although good, block copolymers are more preferred. Moreover, the copolymer of the said styrene-type hydrocarbon and conjugated diene-type hydrocarbon may be used independently, and 2 or more types of copolymer compositions from which styrene content rate differs may be mixed and used.

  Examples of commercial products of the SBS resin include “Clearen” (manufactured by Denki Kagaku Kogyo), “Asaflex” (manufactured by Asahi Kasei Chemicals), “Styloflex” (manufactured by BASF Japan), “K Resin” (Chevron) Philips Chemical Co., Ltd.).

  The styrene copolymer used in the present invention can be obtained by polymerizing a styrene hydrocarbon or a monomer copolymerizable therewith. Here, as a monomer copolymerizable with styrenic hydrocarbon, methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) ) Aliphatic unsaturated carboxylic acid esters such as acrylate. Among these, particularly preferred styrene copolymers include polystyrene and styrene-butyl (meth) acrylate copolymers. In addition, the said (meth) acrylate shows an acrylate and / or a methacrylate.

  The mixed resin constituting the main component of the (III) layer is 5% by mass or more of the styrene copolymer to 60% by mass or more and 95% by mass or less of the copolymer of the styrene hydrocarbon and the conjugated diene hydrocarbon. It is important that the amount is 40% by mass or less. If the content of the styrene copolymer is 5% by mass or more, it can be made into a film with a high waist (rigidity at room temperature), preventing troubles such as poor mounting due to the film being folded back when the bottle is mounted. This is practically preferable. In addition, by setting the content of the styrene copolymer to 40% by mass or less, it is possible to maintain the stretchability at a low temperature and to sufficiently obtain a heat shrinkage rate in a practical temperature range (about 70 ° C. or more and about 90 ° C. or less). In addition, a film excellent in impact resistance can be obtained, which is preferable.

  The copolymer of the styrene hydrocarbon and the conjugated diene hydrocarbon and the styrene copolymer each have a weight (mass) average molecular weight (Mw) of 100,000 or more, preferably 150,000 or more. The upper limit is 500,000 or less, preferably 400,000 or less, and more preferably 300,000 or less. If the weight (mass) average molecular weight (Mw) of the copolymer of styrene-based hydrocarbon and conjugated diene-based hydrocarbon and the styrene-based polymer is 100,000 or more, there is no defect that causes deterioration of the film. . Furthermore, if the weight (mass) average molecular weight of the copolymer of styrene-based hydrocarbon and conjugated diene-based hydrocarbon and the styrene-based copolymer is 500,000 or less, there is no need to adjust the flow characteristics and the extrudability is improved. It is preferable because there is no drawback such as lowering.

  The melt flow rate (MFR) measurement value (measuring condition: temperature 200 ° C., load 49 N) of the copolymer of the styrene hydrocarbon and the conjugated diene hydrocarbon and the styrene copolymer is 2 g / 10 min or more, Preferably, it is 3 g / 10 min or more, and the upper limit is 15 g / 10 min or less, preferably 10 g / 10 min or less, more preferably 8 g / 10 min or less. If the MFR of the polymer is 2 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. Moreover, if the MFR of the polymer is 15 g / 10 min or less, an appropriate cohesive strength of the resin can be obtained, so that a good film strength and elongation can be obtained and the film can be made difficult to become brittle.

<(II) layer>
The layer (II) in the present invention is composed mainly of a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon or a mixed resin of a hydrogenated derivative thereof and a tackifying resin.

  Here, styrene is preferably 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 these may be unhydrogenated or hydrogenated. You may use these individually or in mixture of 2 or more types.

  Further, the copolymer of styrene-based hydrocarbon and conjugated diene-based hydrocarbon or the hydrogenated derivative thereof constituting the main component of the (II) layer has a styrene content of 5% by mass or more of the total amount of the copolymer. It is important that the content is 7% by mass or more, more preferably 10% by mass or more. Moreover, it is important that the upper limit of the styrene content is 50% by mass or less, preferably 40% by mass or less, and more preferably 35% by mass or less. When the styrene content is 5% by mass or more, good compatibility is obtained when the film is returned to the (I) layer and / or the (III) layer (preferably the (III) layer), and the film becomes cloudy. Can be suppressed. On the other hand, when the styrene content is 50% by mass or less, the stress generated between the (I) layer and the (III) layer when stress is applied to the film without reducing the flexibility of the (II) layer. Since the buffering action is exerted, delamination can be suppressed.

  As a hydrogenated derivative of a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon, 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 copolymer of a styrene compound and a conjugated diene hydrocarbon or a hydrogenated derivative thereof can further improve the interlayer adhesion with the (I) layer made of a polyester resin 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. Representative examples of the copolymer of a styrene compound into which a polar group has been introduced 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.

  Next, the adhesion-imparting resin contained in the (II) layer of the present invention is a resin that can increase the interlayer adhesion strength with the layer adjacent to the (II) layer by being contained in the (II) layer. The adhesion-imparting resin is not particularly limited as long as it can increase the interlayer adhesion strength of the (II) layer, but at least one resin selected from the group consisting of petroleum resins, terpene resins, and rosin resins may be used. preferable.

  Examples of the petroleum resin include alicyclic petroleum resins from cyclopentadiene or a dimer thereof, aromatic petroleum resins from the C9 component, and hydrogenated alicyclic petroleum resins. Examples of the terpene resin include terpene resins derived from β-pinene, aromatic modified terpenes, terpene-phenols, hydrogenated terpenes, and the like. Examples of rosin resins include rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin, pentaerythritol, and the like. Among these, a partially hydrogenated petroleum resin is more preferable from the viewpoint of maintaining transparency.

  Specific commercial products of the above-mentioned adhesion-imparting resin include, for example, Mitsui Chemical Co., Ltd. trade names “HI-LET'S”, “PETROZINE”, Arakawa Chemical Industries Ltd. trade name “ALCON”, and Yashara Chemical Co., Ltd. products. Name "Clearon", Idemitsu Petrochemical Co., Ltd. trade name "Imabe", Tonex Co., Ltd. trade name "Escoletsu" and the like.

  Some of the above-mentioned adhesion-imparting resins have various softening temperatures depending on the molecular weight. In the present invention, the softening temperature is 80 ° C or higher, preferably 90 ° C or higher, and 150 ° C or lower, preferably Is preferably 140 ° C. or lower. If the softening temperature is 80 ° C. or higher, after mixing with the above-mentioned copolymer of styrene hydrocarbon and conjugated diene hydrocarbon or a hydrogenated derivative thereof to form a laminated film, it is stored for a long time at a temperature near room temperature. In this case, the change in physical properties over time can be avoided. On the other hand, if it is 150 degrees C or less, since compatibility with the copolymer of a styrene-type hydrocarbon and a conjugated diene-type hydrocarbon or its hydrogenated derivative is maintained favorably, and a physical-property fall with time is hard to occur, it is preferable.

  The content of the tackifying resin in the (II) layer is 5 parts by mass or more and 100 parts by mass or less of the tackifying resin with respect to 100 parts by mass of the copolymer of styrene hydrocarbon and conjugated diene hydrocarbon or hydrogenated derivative thereof. Is desirable. If the mass ratio of the tackifying resin is 5 parts by mass or more, it is preferable because the effect of improving the interlayer adhesion strength can be sufficiently expected. On the other hand, if it is 100 parts by mass or less, it is preferable because the physical properties of the film are less likely to change over time and the impact resistance is less likely to occur. Therefore, the content of the tackifying resin in the layer (II) is 10 parts by mass of the tackifying resin with respect to 100 parts by mass of the copolymer of styrene hydrocarbon and conjugated diene hydrocarbon or its hydrogenated derivative. More preferably, it is 80 parts by mass or less.

  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>

  The heat shrinkable film of the present invention is not particularly limited as long as it has at least a three-layer structure having a (II) layer between the (I) layer and the (III) layer. 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 of the present invention is excellent in stiffness (rigidity at room temperature) and heat shrink characteristics, small in natural shrinkage, sufficiently suppressed delamination, and transparent upon regeneration addition It is possible to obtain a heat-shrinkable laminated film excellent in properties and suitable for applications such as shrink wrapping, shrink tying wrapping and shrinkage labels 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 thickness of the entire film is 10% or more, preferably 15% or more, more preferably 20%, and the upper limit of the thickness ratio is 70% or less, preferably 60% or less, more preferably. 50% or less. The thickness ratio of the (III) layer to the total film thickness is 20% or more, preferably 25% or more, more preferably 30% or more, and the upper limit is 80% or less, preferably 75% or less, more preferably 70%. % Or less. Further, the layer (II) 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 preferably 6 μm or less, preferably 5 μm or less. 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. Further, the lower limit of the total thickness of the film is not particularly limited, but is preferably 20 μm or more in consideration of the handleability of the film.

<Physical and mechanical properties>
As for the waist (rigidity at room temperature) of the film of the present invention, the tensile elastic modulus in the direction orthogonal to the main shrinkage direction of the film is preferably 1400 MPa or more, more preferably 1500 MPa, and more preferably 1600 MPa or more. Further preferred. Moreover, the upper limit of the tensile elastic modulus of the heat-shrinkable film usually used is about 3000 MPa, preferably about 2900 MPa, and more preferably about 2800 MPa. If the tensile modulus of elasticity in the direction perpendicular to the main shrinkage direction of the film is 1400 MPa or more, the waist (rigidity at room temperature) of the entire film can be increased, and even when the thickness of the film is reduced, the PET bottle When a film made in a container is covered with a labeling machine or the like, it is difficult to cause problems such as being obliquely covered or being liable to decrease the yield due to film folding or the like. 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, in addition to adjusting the composition of the resin constituting each layer to the range specified in the present invention, the thickness ratio of the (I) layer to the total film thickness is 10% or more. Adjustment to 70% or less and adjustment of the thickness of the (II) layer to 5 μm or less are mentioned.
In this specification, the main shrinkage direction of the film means the larger one of the longitudinal direction and the transverse direction in the stretching direction. For example, when the film is attached to a bottle, it is a direction corresponding to the outer peripheral direction.

  Next, it is important that the film of the present invention has a thermal shrinkage rate of 40% 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. Considering such industrial productivity, a film having a heat shrinkage rate of 40% or more under the above conditions is preferable because it can sufficiently adhere to 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 40% or more, preferably 45% or more, more preferably 50% or more in the main shrinkage direction in at least one direction, The upper limit is 85% or less, preferably 80% or less, and more preferably 75% or less.

  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 at 70 ° C. for 10 seconds, and the upper limit is 35%. Below, it is preferably 30% or less, more preferably 25% or less. By setting the thermal shrinkage rate in the main shrinkage direction of the film at 70 ° C. to 5% or more, shrinkage unevenness that can be locally generated when a bottle is attached with a steam shrinker is reduced. As a result, wrinkles, avatars, etc. Formation 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, at least one of the heat shrinkage rates is 40% or more (85% or less) at 80 ° C., 5% or more and 35% or less at 70 ° C., and the heat shrinkage rate in the direction orthogonal to the main shrinkage direction is 10% at 80 ° C. In order to achieve the following, the composition of the resin constituting each layer is adjusted within the range specified in the present invention (particularly, the styrene-based carbonization in the styrene-based hydrocarbon-conjugated diene-based hydrocarbon copolymer in the II and III layers). It is important to adjust the hydrogen content, the content of the entire resin, and the polymerization mode of the copolymer. In addition, the thickness ratio of the (I) layer to the thickness of the entire film is 10% to 70%, the thickness of the (II) layer is 5 μm or less, and the stretching ratio is 2 to 10 times, stretching The thermal contraction rate in the main shrinkage direction and the orthogonal direction can also be adjusted by appropriately controlling the temperature in the range of 60 ° C. or higher and 130 ° C. or lower.

  The natural shrinkage rate of the film of the present invention is preferably as small as possible. Generally, the natural shrinkage rate of a heat-shrinkable film is, for example, less than 3.0% after 30 days of storage at 30 ° C. and 50% RH. Is 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 of the present invention, adjusting the composition of the resin constituting each layer within the range specified in the present invention, and the thickness of the (I) layer with respect to the thickness of the entire film is mentioned. It is also possible to adjust the ratio to 10% or more and 70% or less.

  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. As a means for adjusting the haze value of the film of the present invention within the above range, in addition to adjusting the composition of the resin constituting each layer to the composition specified in the present invention, the thickness ratio of each layer, particularly the total film thickness (I ) Adjusting the layer thickness ratio to 10% or more and 70% or less.

  The film of the present invention is, for example, 30 parts by mass or less, preferably 25 parts by mass or less, based on 100 parts by mass of the film (I) and / or (III) (preferably (III) layer). Preferably, even when a film having a thickness of 20 parts by mass or less is regenerated and added, a haze value when a film having a thickness of 50 μm is measured in accordance with JIS K7105 is 10% or less, preferably 7% or less, more preferably 5% or less. It is. 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 an environment of 0 ° C., particularly in the label application, the elongation is 150% or more in the film take-off (flow) direction (MD), preferably 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. The means for adjusting the tensile elongation at break of the film of the present invention to the above-mentioned value is within the range specified by the present invention for the composition of the resin constituting each layer (especially styrene hydrocarbon-conjugated diene hydrocarbon in the II and III layers). It is important to adjust the content of styrene-based hydrocarbons in the copolymer, the content with respect to the entire resin, and the adjustment of the polymerization mode of the copolymer), and the thickness of the (I) layer relative to the thickness of the entire film In addition to setting the ratio to 10% to 70%, the mass ratio of the styrene copolymer of the (III) layer can be adjusted to 40% by mass or less.

  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 means for ensuring the delamination strength 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, and that the thickness of the (II) layer is 0.5 μm or more.

  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. 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, a corner 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 finishing properties, in addition to the heat-shrinkable label material of plastic molded products that are 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 elasticity modulus According to JISK7127, it measured about the direction (longitudinal direction) orthogonal to the main shrinkage | contraction direction of a film on the conditions of temperature 23 degreeC. 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. For the thermal shrinkage, the ratio of shrinkage to the original size before shrinkage was expressed as a% value in the vertical and horizontal directions.

(3) Natural shrinkage rate The film was cut to a size of 100 mm in length and 1000 mm in width, left in a thermostatic bath at 30 ° C. for 30 days, the amount of shrinkage relative to the original size before shrinkage was measured in the main shrinkage direction, and the ratio Is 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) Low temperature tensile elongation at break In accordance with JIS K7127, measurement was performed in a direction (longitudinal direction) perpendicular to the main shrinkage direction of the film under the conditions of a temperature of 0 ° C. and a test speed of 100 mm / min.

(6) 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

(7) Haze value of film after return After the obtained heat-shrinkable laminated film was pulverized using a pulverizer and regenerated into pellets, an amount corresponding to 30% by mass relative to the total amount of the film was added to the intermediate layer (III ) And returned to the layer to obtain a regenerated additive 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, Eastman Chemical Co., Ltd. polyester resin, trade name “copyester 6663” (hereinafter abbreviated as “PETG”) is used as layer (I), and Asahi Kasei Chemicals SBS (styrene / butadiene = 71/29 Vicat softening) Point 70 ° C.) (hereinafter abbreviated as “M1”): 45% by mass, SBS manufactured by Asahi Kasei Chemicals Corporation (styrene / butadiene = 82/18 Vicat softening point 73 ° C.) (hereinafter abbreviated as “M2”): 35% by mass GPPS product name “HF77” (hereinafter abbreviated as M3) manufactured by PS Japan Co., Ltd .: 100 parts by mass of a mixed resin consisting of 20% by mass, an antioxidant (trade name: Sumilizer GS manufactured by Sumitomo Chemical Co., Ltd.) 0.3 The resin to which part by mass is added is the (III) layer, and the SIS product name “Clayton D1124” (hereinafter “ Abbreviated as D1 "): 85% by mass manufactured by Arakawa Chemical Industries, Ltd. partially hydrogenated petroleum resin trade name" ARKON M90 "(hereinafter abbreviated as" AD4 "): a mixed resin of 15 mass% (II) layer, Each was put into a separate single screw extruder manufactured by Mitsubishi Heavy Industries, Ltd., melted and mixed at a set temperature of 230 ° C., and the thickness of each layer was (I) layer / (II) layer / (III) layer / (II) layer / ( I) Layer = co-extruded from 3 types and 5 layers dies so as to be 40 μm / 10 μm / 150 μm / 10 μm / 40 μm, taken up with a cast roll at 50 ° C., cooled and solidified to obtain an unstretched laminated sheet having a width of 300 mm and a thickness of 250 μm. It was. Next, the film was stretched 5.0 times in the transverse uniaxial direction at a preheating temperature of 110 ° C. and a stretching temperature of 93 ° C. using a film tenter manufactured by Kyoto Machine Co., 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, in Example 1, the mass ratio of M1, M2 and M3 used in the (III) layer was M1: 35 mass%, M2: 30 mass%, M3: 35 mass%, and (II) Example 1 except that the mass ratio of AD1 used for the layer and the SIS product name “HIBLER 5125” (hereinafter abbreviated as “AD2”) manufactured by Kuraray Co., Ltd. was changed to AD1: 60 mass% and AD2: 40 mass%. 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, in Example 2, a heat-shrinkable laminated film was obtained in the same manner as in Example 1 except that AD1 alone was used for the (II) layer. The results of evaluating the obtained film are shown in Table 2.

Example 4
As shown in Table 1, in Example 1, the mass ratio of M1, M2 and M3 used in the (III) layer was M1: 45 mass%, M2: 25 mass%, M3: 30 mass%, and (II) A heat-shrinkable laminated film was obtained in the same manner as in Example 1 except that the layer was changed to a mixed resin of AD2 : 70% by mass and AD4: 30% by mass. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 1)
As shown in Table 1, in Example 3, AD1 used for the (II) layer was changed to ethylene-vinyl acetate copolymer (VA content 14%) manufactured by Mitsui DuPont Polychemical Co., Ltd., trade name “Evaflex EV560” (Hereinafter abbreviated as “AD3”), a heat-shrinkable laminated film was obtained in the same manner as in Example 3. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 2)
As shown in Table 1, in Example 1, a heat-shrinkable laminated film was prepared in the same manner as in Example 1 except that the layer (III) was a mixed resin of M1: 40% by mass and M3: 60% by mass. However, breakage occurred during film stretching, and a heat-shrinkable laminated film stretched at a predetermined magnification could not be obtained.

(Comparative Example 3)
As shown in Table 1, in Example 1, there was no (II) layer, and the thickness of each layer in the unstretched laminated sheet was (I) layer / (III) layer / (I) layer = 45 μm / 160 μm / A heat-shrinkable laminated film was obtained in the same manner as in Example 1 except that the thickness was changed to 45 μm. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 4)
As shown in Table 1, in Example 1, the heat-shrinkable laminated film was obtained in the same manner as in Example 1 except that the layer (III) was a mixed resin of M1: 60% by mass and M2: 40% by mass. It was. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 5)
As shown in Table 1, in Example 1, the thickness of each layer in the unstretched laminated sheet (I) layer / (II) layer / (III) layer / (II) layer / (I) layer = 10 μm / 10 μm / A heat-shrinkable laminated film was obtained in the same manner as in Example 1 except that the thickness was 210 μm / 10 μm / 10 μm. The results of evaluating the obtained film are shown in Table 2.

  From Table 1, the films of Examples 1 to 4 constituted by the composition, heat shrinkage rate and natural shrinkage rate specified in the present invention are waist (tensile elastic modulus of laminated film), heat shrinkage rate, natural shrinkage rate, delamination. The strength and transparency at the time of return were superior to those of Comparative Examples 1 to 4, and the shrink finish was equal to or higher than that of Comparative Examples 1 to 4.

  On the other hand, when an ethylene-vinyl acetate copolymer was used as the resin constituting the (II) layer (Comparative Example 1), the haze value at the time of regeneration addition was significantly lowered. Further, when the styrene content of the styrene resin constituting the (III) layer is large (Comparative Example 2), the stretchability is lowered, breakage occurs during stretching, and a film having a heat shrinkage of 40% or more is obtained. There wasn't. Further, when the layer (II) was not provided (Comparative Example 3), sufficient delamination strength was not obtained, and delamination occurred during the test. Further, when the layer (III) did not contain a styrene copolymer (Comparative Example 4), the tensile elastic modulus of the whole laminated film was lowered, and the obtained film was low. Further, when the thickness ratio of the (I) layer was outside the range defined in the present invention (Comparative Example 5), the thermal shrinkage rate at 80 ° C. was less than 40% and the natural shrinkage rate was increased.

  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.

  The film of the present invention is a film with low natural shrinkage that is excellent in film stiffness, heat shrinkage properties, and transparency at the time of regeneration addition, and can be used for various applications such as various shrink wrapping, shrinkage binding, and shrinkage labels. .

Claims (10)

(I) A laminated film comprising at least three layers having a (II) layer between a layer and a (III) layer, wherein each layer is made of a resin having the following components as main components, and the thickness relative to the thickness of the entire film (I) The layer thickness ratio is 10% or more and 70% or less, and the thermal shrinkage rate when immersed in warm water at 80 ° C. for 10 seconds is 40% or more in at least one direction, and 30 ° C. and 50% RH. A heat-shrinkable laminated film characterized by having a natural shrinkage rate of less than 3% when stored in an atmosphere for 30 days.
(I) layer: polyester resin (II) layer: a copolymer of styrene hydrocarbon and conjugated diene hydrocarbon or a hydrogenated derivative thereof, and the content of styrene hydrocarbon is 5 mass% or more and 50 mass % Resin or less (III) layer: a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon and a styrene copolymer, the copolymer of the styrene hydrocarbon and the conjugated diene hydrocarbon Mixture in which the mass ratio of the coalescence and the styrene copolymer is 60/40 to 95/5   The said (II) layer contains 5 mass parts or more and 100 mass parts or less of tackifying resin with respect to 100 mass parts of the copolymer of styrene hydrocarbon and conjugated diene hydrocarbon or its hydrogenated derivative. The heat-shrinkable laminated film described in 1.   The heat-shrinkable laminated film according to claim 2, wherein the tackifying resin is at least one selected from the group consisting of petroleum resins, terpene resins, and rosin resins.   The polyester resin constituting the main component of the (I) layer comprises an aromatic dicarboxylic acid component and a diol component, and the total diol component contains 1,4-cyclohexanedimethanol in an amount of 15 mol% to 50 mol%. The heat-shrinkable laminated film according to any one of claims 1 to 3, wherein the heat-shrinkable laminated film is a resin mainly composed of an amorphous polyethylene terephthalate resin.   The content of styrene hydrocarbon in the copolymer of styrene hydrocarbon and conjugated diene hydrocarbon constituting the main component of the (III) layer is 55% by mass or more and 90% by mass or less. 5. The heat shrinkable laminated film according to any one of 4 above.   The heat-shrinkable laminated film according to any one of claims 1 to 5, wherein a tensile elastic modulus in a direction orthogonal to the film main shrinkage direction measured in accordance with JIS K7127 is 1400 MPa or more. The heat-shrinkable laminated film according to any one of claims 1 to 6, wherein the thickness of the (II) layer is from 0.5 µm to 5 µm. Molded article using as a substrate a heat-shrinkable laminate film according to any one of claims 1 to 7. A heat-shrinkable label using the heat-shrinkable laminated film according to any one of claims 1 to 7 as a substrate. A container equipped with the molded article according to claim 8 or the heat-shrinkable label according to claim 9 .