JP2009012465A - Laminated film, stretched film using the film, heat-shrinkable film, molded product, heat-shrinkable label, and container equipped with the label - Google Patents

Abstract

[Problem] To provide a laminated film suitable for uses such as packaging, shrink-bound packaging, and shrink labels, which has excellent finish, excellent transparency after regeneration addition, and excellent interlayer adhesion.
A resin composition comprising at least three layers having a (III) layer between the following (I) layer and (II) layer, and comprising a polylactic acid resin (A) having (I) layer as a main component The polylactic acid resin (A) and the polyolefin resin (B) in the layer (II), and the polylactic acid resin (A) in which the content of the polylactic acid resin (A) is contained in the layer (III) ) Resin composition less than the content of (III), the layer (III) contains the polylactic acid resin (A) and the polyolefin resin (B), and the content of the polylactic acid resin (A) is the layer (I) The resin composition is less than the content of the polylactic acid resin (A) contained in the resin.
[Selection figure] None

Description

  The present invention relates to a laminated film in which different kinds of materials are laminated, and more specifically, a laminated film that is excellent in transparency and finish and is difficult to peel between layers, and suitable for applications such as packaging, shrink-bound packaging, and shrink labels, and The present invention relates to a stretched film, a heat-shrinkable film, a molded product, a heat-shrinkable label, and a container equipped with the label.

  Conventionally, as a film used as a packaging material, films such as polyester such as polyethylene terephthalate, polyolefin such as polyethylene and polypropylene, and nylon are widely used.

  However, since such a film that has been used conventionally does not decompose in a natural environment or has a very low decomposition rate, when it is left after use or buried in the soil, it is semi-permanently grounded. There was a problem that it would remain in the ground. Moreover, when it is dumped into the ocean, the scenery is damaged and the living environment of marine life is destroyed. Furthermore, in the case of incineration treatment, waste treatment becomes a social problem along with the expansion of consumption, such as promoting the deterioration of the incinerator due to its high combustion heat.

On the other hand, since polylactic acid is decomposed when discarded in the natural environment and an effect of reducing CO ₂ gas can be expected, a film mainly composed of polylactic acid has been developed as a film material. For example, a laminated film combining a polyolefin-based resin and a polylactic acid-based resin has been reported (see Patent Document 1), and this film contains an outer layer containing a filler in a range of 35 mass% to 80 mass%. Therefore, there is a problem that the stretched film is inferior in transparency and mechanical strength. Furthermore, since the film described in Patent Document 3 has a large number of micropores on the surface of the film, it is inferior in printability, slipperiness, etc., and is unsuitable as a label application for printing.

  On the other hand, a shrink sheet having a layer mainly composed of a polyolefin resin and a layer mainly composed of a polylactic acid resin has also been reported (see Patent Document 2). However, this shrinkable sheet is made by the inflation method for the purpose of shrink-wrapping films such as lunch boxes and side dishes sold at convenience stores, etc., and as a heat-shrinkable label application that requires low-temperature high-shrinkability When used, there is a problem that sufficient low temperature shrinkage cannot be obtained. Furthermore, since this shrinkable sheet is a laminated sheet having a polylactic acid resin layer as a core material and a polyolefin resin layer on both outer layers, it is inferior in sealing properties and solvent resistance when making cylindrical seal bags, There was a problem that it was not suitable for shrinkable label applications. Further, when a recyclable resin generated from trimming loss such as ears of the shrink sheet is added (hereinafter also referred to as “regeneration addition”), light scattering occurs at the interface between the polyolefin resin and the polylactic acid resin. As a result, the transparency of the film is lowered, and there is a problem that good transparency cannot be obtained. Furthermore, when a shrink label made of this film is attached to a container, the adhesive layer may not follow the shrinkage of the film at high shrinkage (for example, 30% or more), and the intermediate layer and the front and back layers may peel off. There was a problem that there was.

In order to overcome the above-mentioned problems, in the material design in which different materials are combined, a compatibilizing agent that makes them compatible is often used. For example, Patent Document 3 reports a polylactic acid resin composition comprising polylactic acid and a modified olefin compound, and Patent Document 4 also discloses polylactic acid and an aliphatic polyester other than polylactic acid and a modified polyolefin compound. A polylactic acid-based resin composition has been reported. Although these are all excellent in strength and impact resistance and can control the degradation rate by microorganisms, they are modified olefins containing reactive polar groups such as glycidyl groups and maleic anhydride as compatibilizers. Since the compound and the modified polyolefin compound are used, there remains a problem that defects such as generation of defects during production and prototyping, poor appearance, or clogging of a filtration device in the production line occur. Furthermore, when used as a shrinkable film, the adhesive layer may not follow the shrinkage of the film, and the problem that the intermediate layer and the front and back layers may peel off has not been solved.
JP 2002-347184 A JP 2002-019053 A JP 9-316310 A JP 2001-123055 A

  The present invention has been made in view of the above problems, and the object of the present invention is packaging, shrinkage having excellent finish and transparency after regeneration addition, and excellent interlayer adhesion. An object of the present invention is to provide a laminated film suitable for uses such as bundling packaging and shrinkage labels.

  Another subject of the present invention is a stretched film, a heat-shrinkable film, a molded product, a heat-shrinkable label, and a container equipped with the label, using the film suitable for applications such as packaging, shrink-bound packaging, and shrinkable labels. Is to provide.

As a result of intensive studies on the composition of each 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 completed the present invention.
That is, the problem of the present invention is solved by a laminated film consisting of at least three layers (hereinafter also referred to as “laminated film of the present invention”) having a (III) layer between the following (I) layer and (II) layer. Is done.
(I) Layer: Resin composition containing polylactic acid resin (A) as a main component (II) Layer: Polylactic acid resin (A) and polyolefin resin (B) Resin composition in which content of A) is less than content of polylactic acid resin (A) contained in layer (III) (III) layer: containing polylactic acid resin (A) and polyolefin resin (B) The content of the polylactic acid resin (A) is less than the content of the polylactic acid resin (A) contained in the (I) layer.

The laminated film of the present invention promotes the compatibilization of the polylactic acid resin (A) and the polyolefin resin (B) in the layer (II), the layer (III), or the layer (II) and the layer (III). The compatible resin (C) can be contained. In this case, the compatible resin (C) is a group consisting of the following resin (c-1), resin (c-2), and resin (c-3) And the content thereof is 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin composition constituting the (II) layer or the (III) layer.
Resin (c-1): a segment (a) selected from the group consisting of an ethylene homopolymer, an ethylene copolymer, an acid-modified olefin copolymer, an olefin thermoplastic elastomer, and a styrene thermoplastic elastomer , A copolymer having a segment (b) formed from at least one vinyl monomer Resin (c-2): Vinyl acetate, acrylic acid, methacrylic acid, ethyl acrylate, ethyl methacrylate, acrylic acid Copolymer of ethylene with at least one selected from the group consisting of methyl, methyl methacrylate, maleic anhydride, glycidyl acrylate, and glycidyl methacrylate Resin (c-3): Aromatic hydrocarbon and conjugated diene Hydrogenated products of copolymers of aromatic hydrocarbons, copolymers of aromatic vinyl hydrocarbons and conjugated diene hydrocarbons Or copolymers obtained by introducing a polar group thereto

  The laminated film of the present invention preferably has a haze value based on JIS K7105 of 12% or less. In the laminated film of the present invention, the polyolefin resin (B) is preferably a polyethylene resin, a polypropylene resin, or a mixture thereof. Moreover, the laminated | multilayer film of this invention can contain hydrocarbon resin in (II) layer or (III) layer.

  Another subject of the present invention is a stretched film obtained by stretching the laminated film of the present invention in at least one direction; the laminated film of the present invention is stretched in at least one direction and immersed in warm water at 80 ° C. for 10 seconds. A heat-shrinkable film having a heat shrinkage rate of 20% or more in the film main shrinkage direction; a molded product using the laminated film, stretched film, or heat-shrinkable film as a substrate; a heat-shrinkable label; Solved by a container with a label.

  According to the present invention, a laminate having excellent finish, excellent transparency after regeneration addition, and excellent interlayer adhesion, suitable for applications such as packaging, shrink-bound packaging and shrink labels. A film can be provided.

  Furthermore, according to the present invention, a stretched film, a heat-shrinkable film, a molded product, a heat-shrinkable label having excellent finish, excellent transparency after regeneration addition, and excellent interlayer adhesion And a container equipped with the label.

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

  In the present specification, “main component” is intended to allow other components to be included within a range that does not interfere with the action and effect of the resin constituting each layer. Further, this term does not limit the specific content, but it is 60% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and 100% by mass with respect to the total components of each layer. It is a component occupying the following content.

  Further, in the present specification, the “film” is a thin flat product whose thickness is extremely small compared to the length and width and whose maximum thickness is arbitrarily limited, and is usually provided in the form of a roll. “Sheet” refers to a product that is thin by definition in the Japanese Industrial Standard (JIS), and whose thickness is usually small and flat for the length and width. However, the boundary between the sheet and the film is not clear, and it is not necessary to distinguish both in terms of the wording in the present invention. Therefore, in the present invention, the term “film” includes “sheet”.

[Laminated film]
The laminated film of the present invention is a laminated film comprising at least three layers having a (III) layer between the following (I) layer and (II) layer.
(I) Layer: Resin composition containing polylactic acid resin (A) as a main component (II) Layer: Polylactic acid resin (A) and polyolefin resin (B) Resin composition in which content of A) is less than content of polylactic acid resin (A) contained in layer (III) (III) layer: containing polylactic acid resin (A) and polyolefin resin (B) The content of the polylactic acid resin (A) is less than the content of the polylactic acid resin (A) contained in the (I) layer.

<(I) layer>
In the present invention, the (I) layer is composed of at least one polylactic acid resin (A). The polylactic acid resin (A) is a homopolymer of D-lactic acid or L-lactic acid, or a copolymer thereof, and a mixture thereof is also included. More specifically, poly (D-lactic acid) whose structural unit is D-lactic acid, poly (L-lactic acid) whose structural unit is L-lactic acid, and a copolymer of L-lactic acid and D-lactic acid. Poly (DL-lactic acid) or a mixture thereof.

  When the polylactic acid resin (A) is a copolymer of D-lactic acid and L-lactic acid, the copolymerization ratio of D-lactic acid and L-lactic acid is D-lactic acid / L-lactic acid = 99.8 to 75. /0.2-25, or D-lactic acid / L-lactic acid = 0.2-25 / 99.8-75, preferably D-lactic acid / L-lactic acid = 99.5-80 / More preferably, it is 0.5-20 or D-lactic acid / L-lactic acid = 0.5-20 / 99.5-80. Polylactic acid composed of D-lactic acid alone or L-lactic acid alone exhibits very high crystallinity, has a high melting point, and tends to be excellent in heat resistance and mechanical properties. However, when used as a heat-shrinkable film, it usually involves a printing process and a bag-making process using a solvent, so that the crystallinity of the constituent material itself is moderately lowered in order to improve printability and solvent sealability. Is required. Moreover, when crystallinity is too high, orientation crystallization advances at the time of extending | stretching, and there exists a tendency for shrinkage | contraction characteristic to fall. From such a viewpoint, the polylactic acid resin used in the present invention is D-lactic acid / L-lactic acid = 99 to 85/1 to 15, or D-lactic acid / L-lactic acid = 1 to 15/99 to 85. A mixture is preferred.

  As the polylactic acid resin (A), copolymers of D-lactic acid and L-lactic acid having different copolymerization ratios can be mixed and used. In that case, what is necessary is just to make it the average value of the copolymerization ratio of D-lactic acid and L-lactic acid of a some lactic acid type polymer fall in the said range. Two or more types of polylactic acid resins having different copolymer ratios of D-lactic acid and L-lactic acid are mixed in accordance with the intended use, and the crystallinity is adjusted to balance heat resistance and heat shrinkage characteristics. be able to.

  The polylactic acid resin (A) may be a copolymer of lactic acid and α-hydroxycarboxylic acid, aliphatic diol, or aliphatic dicarboxylic acid. Here, the “α-hydroxycarboxylic acid” copolymerized with the lactic acid resin includes optical isomers of lactic acid (D-lactic acid for L-lactic acid, and L-lactic acid for D-lactic acid, respectively). Glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methylbutyric acid, 2-hydroxy Bifunctional aliphatic hydroxy-carboxylic acids such as caprolactone and lactones such as caprolactone, butyl lactone and valerolactone. Examples of the “aliphatic diol” copolymerized with the lactic acid resin include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like. Examples of the “aliphatic dicarboxylic acid” to be copolymerized include succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanedioic acid. The copolymerization ratio of the copolymer of lactic acid and α-hydroxycarboxylic acid, aliphatic diol, or aliphatic dicarboxylic acid is lactic acid / α-hydroxycarboxylic acid, aliphatic diol, or aliphatic dicarboxylic acid = 90/10 The range is preferably 10/90, more preferably 80/20 to 20/80, and even more preferably 30/70 to 70/30. If the copolymerization ratio is within the above range, a film having a good balance of physical properties such as rigidity, transparency and impact resistance can be obtained.

  The polylactic acid resin (A) can be produced by a known polymerization method such as a condensation polymerization method or a ring-opening polymerization method. For example, in the case of a condensation polymerization method, a polylactic acid resin having an arbitrary composition can be obtained by directly dehydrating condensation polymerization of D-lactic acid, L-lactic acid, or a mixture thereof. Further, in the ring-opening polymerization method, a lactide which is a cyclic dimer of lactic acid is subjected to ring-opening polymerization in the presence of a predetermined catalyst while using a polymerization regulator or the like, if necessary. A lactic acid resin can be obtained. The lactide includes DL-lactide, which is a dimer of L-lactic acid. By mixing and polymerizing these as necessary, a polylactic acid resin having an arbitrary composition and crystallinity can be obtained. it can. Furthermore, a small amount of chain extender such as a diisocyanate compound, diepoxy compound, acid anhydride, acid chloride, etc. may be used for the purpose of increasing the molecular weight.

  The weight (mass) average molecular weight of the polylactic acid resin (A) is 20,000 or more, preferably 40,000 or more, more preferably 60,000 or more, and the upper limit is 400,000 or less, preferably 350,000. Hereinafter, it is more preferably 300,000 or less. When the weight (mass) average molecular weight of the polylactic acid-based resin (A) is 20,000 or more, an appropriate resin cohesive force can be obtained, and the film can be prevented from being insufficiently stretched or embrittled. Can do. On the other hand, when the weight (mass) average molecular weight of the polylactic acid resin (A) is 400,000 or less, the melt viscosity can be lowered, which is preferable from the viewpoint of production and productivity improvement.

  Commercially available products of polylactic acid resin (A) include, for example, trade name “NatureWorks” (manufactured by NatureWorks), trade name “LACEA” (manufactured by Mitsui Chemicals), and “U'z series” (manufactured by Toyota Motor Corporation). Etc.

  In order to improve impact resistance, the rubber component other than the polylactic acid resin (A) can be added to the (I) layer within a range that does not impair transparency and flexibility. The rubber component is not particularly limited, but is an aliphatic polyester other than the polylactic acid resin (A), an aromatic-aliphatic polyester, a copolymer of a diol, a dicarboxylic acid, and a lactic acid resin, or a core-shell structure rubber. , And ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA), ethylene- (meth) acrylic acid copolymer (EMA), An ethylene-methyl (meth) acrylic acid copolymer (EMMA) etc. can be used conveniently.

  As the aliphatic polyester obtained by condensing an aliphatic diol and an aliphatic dicarboxylic acid, one or two or more kinds of aliphatic diols and aliphatic dicarboxylic acids described below are condensed or condensed, Alternatively, a polymer obtained as a desired polymer by jumping up the molecular weight with an isocyanate compound or the like as required can be mentioned. Here, examples of the aliphatic diol include ethylene glycol, propylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, and suberin. Examples include acid, sebacic acid, dodecanedioic acid and the like.

  In addition, examples of the aliphatic polyester obtained by ring-opening condensation of cyclic lactones include ring-opening polymers such as ε-caprolactone, σ-valerolactone, and β-methyl-σ-valerolactone, which are cyclic monomers. These cyclic monomers can be copolymerized by selecting not only one kind but also plural kinds.

  Examples of synthetic aliphatic polyesters include copolymers of cyclic acid anhydrides and oxiranes, such as copolymers of succinic anhydride and ethylene oxide, copolymers of propion oxide, and the like. it can.

  Representative of aliphatic polyesters other than these polylactic acid-based resins (A) is “Bionore” (manufactured by Showa Polymer Co., Ltd.) obtained by polymerizing succinic acid, 1,4-butanediol and adipic acid. Can be obtained commercially. Moreover, as a thing obtained by ring-opening condensation of (epsilon) -caprolactone, "Cell Green" (made by Daicel Chemical Industries Ltd.) is mentioned.

  Next, as the aromatic-aliphatic polyester, those having crystallinity lowered by introducing an aromatic ring between the aliphatic chains can be used. The aromatic-aliphatic polyester is obtained, for example, by condensing an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, and an aliphatic diol.

  Here, examples of the aromatic dicarboxylic acid include isophthalic acid, terephthalic acid, and 2,6-naphthalenedicarboxylic acid, and terephthalic acid is most preferably used. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, and adipic acid is most preferably used. Two or more types of aromatic dicarboxylic acids, aliphatic dicarboxylic acids or aliphatic diols may be used.

  Typical examples of the aromatic aliphatic polyester include a copolymer of tetramethylene adipate and terephthalate, a copolymer of polybutylene adipate and terephthalate, and the like. EsterBio (manufactured by Eastman Chemicals) as a copolymer of tetramethylene adipate and terephthalate, and Ecoflex (manufactured by BASF) as a copolymer of polybutylene adipate and terephthalate are commercially available.

  Examples of the structure of the polylactic acid resin, diol and dicarboxylic acid copolymer include random copolymers, block copolymers, and graft copolymers, and any structure may be used. However, a block copolymer or a graft copolymer is preferable from the viewpoint of impact resistance and transparency of the film. A specific example of the random copolymer is “GS-Pla” (manufactured by Mitsubishi Chemical Corporation), and a specific example of the block copolymer or graft copolymer is “Plamate” (manufactured by DIC).

  The production method of the copolymer of polylactic acid resin, diol and dicarboxylic acid is not particularly limited, but polyester or polyether polyol having a structure obtained by dehydration condensation of diol and dicarboxylic acid is converted to lactide and ring-opening polymerization or transesterification. The method obtained by letting it be mentioned. Further, there is a method in which a polyester or polyether polyol having a structure obtained by dehydration condensation of a diol and a dicarboxylic acid is obtained by dehydration-deglycolization condensation or transesterification with a polylactic acid resin.

  The copolymer of polylactic acid resin, diol and dicarboxylic acid can be adjusted to a predetermined molecular weight using an isocyanate compound or a carboxylic acid anhydride. However, from the viewpoint of workability and mechanical properties, the weight (mass) average molecular weight is 50,000 or more, preferably 100,000 or more, and 300,000 or less, preferably 250,000 or less.

  Next, the core-shell structure rubber is a diene core-shell type polymer such as (meth) acrylic acid-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, (meth) acrylic acid-styrene-acrylonitrile copolymer, etc. Silicone core-shell type copolymers such as silicone- (meth) acrylic acid-methyl (meth) acrylic acid copolymer, silicone- (meth) acrylic acid-acrylonitrile-styrene copolymer, etc. Can be mentioned. Among these, a silicone- (meth) acrylic acid-methyl (meth) acrylic acid copolymer having good compatibility with the polylactic acid resin and having a good balance between impact resistance and transparency of the film is more preferably used. .

  Specifically, “Metablene” (manufactured by Mitsubishi Rayon Co., Ltd.), “Kane Ace” (manufactured by Kaneka Corporation), etc. are commercially available.

  The amount of the rubber component added is desirably 100 parts by mass or less, preferably 80 parts by mass or less, and more preferably 70 parts by mass or less with respect to 100 parts by mass of the polylactic acid resin (A). By setting the addition amount of the rubber component to 100 parts by mass or less, the rigidity and transparency of the film can be maintained without being impaired. Moreover, favorable impact resistance can be provided to a film by the addition amount of a rubber component being 10 mass parts or more.

  Further, the (I) layer may contain a (meth) acrylic resin for the purpose of improving the transparency of the film. The (meth) acrylic resin referred to here means a methyl methacrylate homopolymer or a copolymer of methyl methacrylate and another vinyl monomer. Examples of the vinyl monomer include methacrylic acid esters such as ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate; Acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate; methacrylic acid, acrylic acid Unsaturated acids such as styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide and the like. In addition, copolymers of methyl methacrylate and other vinyl monomers include polybutadiene, butadiene / butyl acrylate copolymers, elastomer components such as polybutyl acrylate copolymers, glutaric anhydride units, and glutarimide. Units may be further included. Among them, from the viewpoint of rigidity and moldability, polymethyl methacrylate resin (PMMA), which is a homopolymer of methyl methacrylate, and methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, acrylic A copolymer composed of two or more selected from acid butyl, acrylic acid, and methacrylic acid is preferably used. In this specification, acrylic and methacryl are collectively referred to as (meth) acrylic.

  The (meth) acrylic resin has a weight (mass) average molecular weight of 20,000 or more, preferably 40,000 or more, more preferably 60,000 or more, and an upper limit of 400,000 or less, preferably 350,000. Hereinafter, it is more preferably 300,000 or less. When the weight (mass) average molecular weight is 20,000 or more, it is possible to prevent the film from being insufficiently stretched or embrittled. On the other hand, if the weight (mass) average molecular weight is 400,000 or less, the melt viscosity can be lowered, which is preferable from the viewpoint of production and productivity improvement.

  Commercially available products of the (meth) acrylic resin include, for example, “Sumipex” (manufactured by Sumitomo Chemical Co., Ltd.), “Acrypet” (manufactured by Mitsubishi Rayon Co., Ltd.), “Parapet” (manufactured by Kuraray Co., Ltd.), -Made by Japan), "Delpet" (made by Asahi Kasei) and the like.

  Content with respect to polylactic acid-type resin (A) of the said (meth) acrylic-type resin shall be in the range of polylactic acid-type resin (A) / (meth) acrylic-type resin = 95 / 5-50 / 50 by mass ratio. It is preferable. If the content of the (meth) acrylic resin in the (I) layer is 5% by mass or more based on the total mass of the polylactic acid resin (A) and the (meth) acrylic resin, the shrinkage characteristics and shrinkage of the film The effect of improving finish and transparency can be sufficiently obtained. On the other hand, if the content of the (meth) acrylic resin is 50% by mass or less with respect to the total mass of both resins, the impact resistance of the film is not significantly lowered, and the stretchability at a low temperature can be maintained. The heat shrinkage rate in the practical temperature range (about 70 to 90 ° C.) can be sufficiently obtained. From these facts, the mixed resin in the front and back layers is a polylactic acid resin (A) / (meth) acrylic resin = 90 / by mass ratio of the above-mentioned polylactic acid resin (A) and (meth) acrylic resin. It is more preferable to mix within the range of 10-60 / 40.

<(II) layer>
The (II) layer of the laminated film of the present invention is a resin composition containing the polylactic acid resin (A) and the polyolefin resin (B) described in the (I) layer. The content of A) is less than the content of the polylactic acid resin (A) contained in the (III) layer. (II) The content of the polylactic acid resin (A) contained in the layer is less than the content of the polylactic acid resin (A) contained in the (III) layer, that is, the main component of the (II) layer By setting it as polyolefin resin (B), a softness | flexibility and a moldability can be provided to a laminated | multilayer film.

  The olefin resin (B) is not particularly limited, but is preferably a polyethylene resin, a polypropylene resin, or a mixture thereof from the viewpoints of finish, mechanical properties, and moldability. Since there are various types of polyethylene resins and polypropylene resins depending on the polymerization method and copolymerization component, preferred types are shown below, but the range is not limited thereto.

  When the polyolefin resin (B) is a polyethylene resin, the polyethylene resin is usually a high density polyethylene resin (HDPE), a medium density polyethylene resin (MDPE), a low density polyethylene resin (LDPE), and a linear resin. Examples thereof include low density polyethylene resin (LLDPE). From the viewpoints of stretchability, impact resistance of the film, transparency and the like, a linear low density polyethylene resin (LLDPE) is particularly preferably used.

  Examples of the linear low density polyethylene resin (LLDPE) include a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, preferably 4 to 12 carbon atoms. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 3-methyl-1-butene, 4- Examples thereof include methyl-1-pentene. Of these, 1-butene, 1-hexene, and 1-octene are preferably used. Moreover, you may use the alpha olefin to copolymerize individually by 1 type or in combination of 2 or more types.

The density of the polyethylene resin is 0.80 g / cm ³ or more, more preferably 0.85 g / cm ³ or more, still more preferably 0.90 g / cm ³ or more, and 0.945 g / cm ³ or less, preferably 0. .935g / cm ³ or less, more preferably 0.925 g / cm ³ or less. If the density is 0.80 g / cm ³ or more, the waist (rigidity at room temperature) and heat resistance of the entire film are not significantly lowered, which is practically preferable. On the other hand, if the density is 0.945 g / cm ³ or less, the drawability at a low temperature is maintained, and a heat shrinkage rate in a practical temperature range (about 70 ° C. or more and about 90 ° C. or less) can be obtained sufficiently.

  In addition, the melt flow rate (MFR) of the polyethylene resin is not particularly limited, but usually MFR (JIS K7210, temperature: 190 ° C., load: 21.18 N) is 0.5 g / 10 min or more. It is preferably 1.0 g / 10 min or more, 15 g / 10 min or less, and preferably 10 g / 10 min or less. Here, in order to obtain a film having a uniform thickness, the MFR of the polyethylene resin is preferably selected to be similar to the viscosity at the time of melting of the (I) layer and the (III) layer.

  When the polyolefin resin (B) is a polypropylene resin, examples of the polypropylene resin include homopropylene resin, random polypropylene resin, ethylene-propylene rubber, ethylene-butene rubber, ethylene diene rubber, and the like. Among these, a random polypropylene resin is particularly preferably used from the viewpoints of stretchability, transparency, rigidity, and the like.

  In the random polypropylene resin, the α-olefin copolymerized with propylene preferably includes those having 2 to 20 carbon atoms, more preferably 4 to 12 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1- Examples include hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and the like. In the present invention, from the viewpoints of stretchability, heat shrinkage properties, impact resistance, transparency, rigidity, and the like of the film, random polypropylene having an ethylene unit content of 2% by mass to 10% by mass as the α-olefin is particularly preferable. Preferably used. Moreover, you may use the alpha olefin to copolymerize individually by 1 type or in combination of 2 or more types.

  Further, the melt flow rate (MFR) of the polypropylene resin is not particularly limited, but usually MFR (JIS K7210, temperature: 230 ° C., load: 21.18 N) is 0.5 g / 10 min or more. , Preferably it is 1.0 g / 10g or more, 15 g / 10min or less, Preferably it is 10 g / 10min or less. Here, in order to obtain a film having a uniform thickness, it is preferable to select an MFR that is similar to the viscosity at the time of melting of the (I) layer and the (III) layer.

  The production method of the polyolefin resin (B) is not particularly limited, and a known polymerization method using a known olefin polymerization catalyst, for example, a multisite catalyst or a metallocene catalyst represented by a Ziegler-Natta type catalyst. Examples thereof include a slurry polymerization method, a solution polymerization method, a bulk polymerization method, and a gas phase polymerization method using a single site catalyst represented by the above, and a bulk polymerization method using a radical initiator.

  Specifically, as the polyethylene-based resin, the trade names “Novatech HD, LD, LL”, “Kernel”, “Toughmer A, P” (manufactured by Japan Polytechnics), “Suntech HD, LD” (manufactured by Asahi Kasei Chemicals), “HIZEX” "ULTZEX" "EVOLUE" (Mitsui Chemicals), "Moretech" (Idemitsu Kosan), "UBE polyethylene" "UMERIT" (Ube Industries), "NUC polyethylene" "Nacflex" (Nihon Unicar) And “Engeage” (manufactured by Dow Chemical Co.) are commercially available. In addition, as polypropylene resins, trade names “Novatech PP”, “WINTEC”, “Toughmer XR” (manufactured by Nippon Polypro), “Mitsui Polypro” (manufactured by Mitsui Chemicals), “Sumitomo Noblen”, “Tough Selenium”, “Excellen EPX” ( Sumitomo Chemical Co., Ltd.), "IDEMISUPP", "IDEMISUT Polyolefin" (manufactured by Idemitsu Kosan Co., Ltd.), "Adflex", "Adsyl" (manufactured by Sun Allomer Co., Ltd.), "VERSIFY" (manufactured by Dow Chemical Co., Ltd.) and the like are commercially available. These copolymers can be used alone or in admixture of two or more.

In addition, as the polyolefin resin (B), a polyolefin resin having a crystallization heat amount ΔHc of 40 J / g or less can be suitably used from the viewpoint of transparency. When such a polyolefin resin is mixed with the polylactic acid resin (A), the difference in refractive index between the two resins can be reduced and excellent transparency can be maintained. From the viewpoint of further improving the transparency, the heat of crystallization of the polyolefin resin (B) is preferably 30 J / g or less, more preferably 25 J / g or less, and further preferably 20 J / g or less. preferable. A non-crystalline polyolefin resin that does not express the amount of crystallization heat can also be suitably used.
The crystallization heat quantity ΔHc can be measured using a differential scanning calorimeter (DSC). Specifically, the crystallization heat quantity ΔHc is raised to 200 ° C. at a heating rate of 10 ° C./min and held at 200 ° C. for 5 minutes. Then, it can be expressed as the amount of heat when the temperature is lowered to room temperature at a cooling rate of 10 ° C./min.

  The polyolefin resin (B) having a crystallization heat amount ΔHc of 40 J / g or less includes a polyethylene resin and a polypropylene resin having the crystallization heat amount ΔHc from the viewpoints of flexibility and transparency, mechanical properties and moldability. Or mixtures thereof.

  Examples of such a polyolefin resin (B) include soft polypropylene (trade name “Versify”) manufactured by Dow Chemical Company.

  In the present invention, a hydrocarbon resin may be added to the (II) layer as necessary. Addition of hydrocarbon resins to polyolefin resin (B) suppresses crystallization of polyolefin resins (for example, polyethylene resins and polypropylene resins) and improves film transparency. It is possible to maintain the stretchability of the film and to improve the heat shrinkage characteristics.

  Among the hydrocarbon resins, the petroleum resin includes cyclopentadiene or an alicyclic petroleum resin derived from a dimer thereof and an aromatic petroleum resin derived from a C9 component, and the terpene resin is a terpene resin derived from β-pinene. Examples of rosin-based resins include rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin, pentaerythritol, and the like. The hydrocarbon resins are known to exhibit relatively good compatibility when mixed with polyolefin resins and the like, but it is preferable to use a hydrogenated derivative from the viewpoint of color tone, thermal stability, and compatibility. preferable.

  Specifically, Mitsui Chemicals' product names “Hilets” and “Petrogin”, Arakawa Chemical Industries' product name “Arcon”, Yashara Chemicals' product name “Clearon”, Idemitsu Petrochemical Co., Ltd. ) And trade name “Escolez” of Tonex Co., Ltd. can be used.

  Some of the above hydrocarbon resins have various softening temperatures depending on the molecular weight. In the present invention, those having a softening temperature of 100 ° C. or higher and 150 ° C. or lower, preferably 110 ° C. or higher and 140 ° C. or lower. Preferably used. Here, if the softening temperature is 100 ° C. or higher, when mixed with a polyolefin-based resin, it may bleed on the surface of the sheet, causing blocking, or the mechanical strength of the entire sheet may be reduced and easily broken. And practically preferred. On the other hand, if it is 150 degrees C or less, compatibility with polyolefin-type resin is maintained favorably, it does not bleed on the film surface with time, causing blocking or a decrease in transparency, which is preferable.

  The amount of the hydrocarbon resins added to the (II) layer is preferably 5 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the resin constituting the (II) layer. Here, if the mixing amount of hydrocarbon resins is 5 parts by mass or more, the effect of improving the glossiness and finish of the film surface is remarkable. On the other hand, if the mixing amount of the resin is 80 parts by mass or less, it is preferable that problems such as bleed to the surface with time and the films tend to block each other and impact resistance is reduced are not likely to occur. For these reasons, the amount of the hydrocarbon resins added to the (II) layer is more preferably 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the resin constituting the (II) layer.

  In the present invention, the (II) layer contains the polylactic acid resin (A) usable in the (I) layer or (III) layer in a smaller content than the polylactic acid resin (A) contained in the (III) layer. be able to. That is, the content of the polylactic acid resin (A) contained in the (II) layer is 100 parts by mass or less with respect to 100 parts by mass of the resin other than the polylactic acid resin (A) contained in the (II) layer, The content is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and the content is smaller than that of the polylactic acid resin (A) contained in the (III) layer. Moreover, although a minimum is not specifically limited, It is preferable that it is 3 mass parts or more. If 3 parts by mass or more are mixed, the low-temperature shrinkage rate can be improved when processed into a heat-shrinkable film. On the other hand, the transparency of the obtained laminated film can be maintained by setting the polylactic acid resin (A) to be mixed to 100 parts by mass or less.

<(III) layer>
The (III) layer of the laminated film of the present invention contains a polylactic acid resin (A) and a polyolefin resin (B), and the polylactic acid resin (A) content is included in the (I) layer. It is comprised with a resin composition with less content of lactic acid-type resin (A). Thereby, the (I) layer and the (III) layer can be adhered, and at the same time, the (III) layer and the (II) layer can be adhered. Thus, even when the laminated film having the (I) layer, the (II) layer, and the (III) layer is stretched and then thermally contracted, it can occur between the (I) layer and the (II) layer. Delamination can be suppressed.

  The content of the polylactic acid resin (A) contained in the (III) layer is less than the content of the polylactic acid resin (A) contained in the (I) layer, and further, the polylactic acid resin contained in the (II) layer More than the content of the resin (A). That is, the content of the polylactic acid resin (A) contained in the (III) layer is preferably 25 parts by mass or more with respect to 100 parts by mass of the resin other than the polylactic acid resin (A) contained in the (III) layer. Is 30 parts by mass or more, more preferably 40 parts by mass or more, and 400 parts by mass or less, preferably 300 parts by mass or less, more preferably 250 parts by mass or less. By setting the content of the polylactic acid resin (A) contained in the (III) layer within the above range, the polylactic acid contained in the (III) layer is formed at the boundary surface between the (I) layer and the (III) layer. System resin (A) precipitates and enables adhesion of the (I) layer and (III) layer, and at the same time, the polyolefin-based resin contained in the (III) layer at the interface between the (III) layer and (II) layer The resin (B) is deposited, and the (III) layer and the (II) layer can be bonded, and the laminated film having the (I) layer, the (II) layer, and the (III) layer is stretched, Thereafter, even when the heat shrinkage is performed, an effect that the delamination that may occur between the (I) layer and the (II) layer can be suppressed is obtained.

  The type of the polylactic acid resin (A) and the polyolefin resin (B) used in the (III) layer is not particularly limited, but at least one polylactic acid type described in the (I) layer or (II) layer Resins and polyolefin resins can be suitably used.

<Compatible resin (C)>
In the present invention, the (II) layer, the (III) layer, or the (II) layer and the (III) layer promote the compatibilization of the polylactic acid resin (A) and the polyolefin resin (B). A compatible resin (C) can be contained. The compatible resin (C) is not particularly limited as long as it is a resin that compatibilizes the polylactic acid resin (A) and the polyolefin resin (B), but the following resin (c-1) and resin (c- It is preferable to use at least one copolymer or resin selected from the group consisting of 2) and resin (c-3).
Resin (c-1): a segment (a) selected from the group consisting of an ethylene homopolymer, an ethylene copolymer, an acid-modified olefin copolymer, an olefin thermoplastic elastomer, and a styrene thermoplastic elastomer , A copolymer having a segment (b) formed from at least one vinyl monomer Resin (c-2): Vinyl acetate, acrylic acid, methacrylic acid, ethyl acrylate, ethyl methacrylate, acrylic acid Copolymer of ethylene with at least one selected from the group consisting of methyl, methyl methacrylate, maleic anhydride, glycidyl acrylate, and glycidyl methacrylate Resin (c-3): Aromatic hydrocarbon and conjugated diene Hydrogenated products of copolymers of aromatic hydrocarbons, copolymers of aromatic vinyl hydrocarbons and conjugated diene hydrocarbons Or copolymers obtained by introducing a polar group thereto

  First, the resin (c-1) will be described. Resin (c-1) is a graft copolymer comprising a thermoplastic resin segment (a) and a vinyl polymer segment (b).

  The segment (a) of the resin (c-1) is selected from the group consisting of an ethylene homopolymer, an ethylene copolymer, an acid-modified olefin copolymer, an olefin thermoplastic elastomer, and a styrene thermoplastic elastomer. This is a thermoplastic resin segment. These may be used alone or in combination of two or more.

  Examples of the segment of the ethylene homopolymer include segments such as low density polyethylene and high density polyethylene.

  Examples of the ethylene copolymer segment include ethylene-α-olefin copolymer, ethylene-α-olefin-nonconjugated polyene copolymer, ethylene- (meth) acrylic acid alkyl ester copolymer, ethylene-vinyl acetate. Examples include segments such as copolymers.

  Examples of the α-olefin other than ethylene in the ethylene-α-olefin copolymer and the ethylene-α-olefin-nonconjugated polyene copolymer include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, Examples include 1-decene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 5-methyl-1-hexene. These α-olefins may be used alone or in combination of two or more. Non-conjugated polyenes include 5-ethylidene-2-norbornene (ENB), dicyclopentadiene (DCP), 5-vinyl-2-norbornene, norbornadiene, methyltetrahydroindene (above, cyclic diene), 1,4-hexadiene. 7-methyl-1,6-octadiene (above, chain diene) and 8-methyl-4-ethylidene-1,7-nonadiene, 4-ethylidene-1,7-undecadiene (above, chain triene) Etc.

  Specific examples of the ethylene-α-olefin copolymer segment include segments such as an ethylene-propylene copolymer, an ethylene-butene copolymer, an ethylene-hexene copolymer, and an ethylene-octene copolymer.

  Specific examples of the ethylene-α-olefin-nonconjugated polyene copolymer segment include ethylene-butene-nonconjugated polyene copolymer and ethylene-propylene-nonconjugated polyene copolymer segments. More specifically, an ethylene-propylene-ethylidene norbornene copolymer and an ethylene-propylene-dicyclopentadiene copolymer segment may be mentioned.

  Specific examples of the ethylene- (meth) acrylic acid alkyl ester copolymer segment include: ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-n-butyl acrylate copolymer, ethylene -Segments such as an isobutyl acrylate copolymer, an ethylene-acrylic acid 2-ethylhexyl copolymer, and an ethylene-methyl methacrylate copolymer.

  Specific examples of the acid-modified olefin copolymer segment include an acid-modified product of ethylene-butene copolymer (maleic anhydride and maleic acid, the same applies hereinafter), an acid-modified product of ethylene-propylene copolymer, Acid-modified product of ethylene-hexene copolymer, acid-modified product of ethylene-octene copolymer, acid-modified product of ethylene-butene-nonconjugated polyene copolymer, acid modification of ethylene-propylene-nonconjugated polyene copolymer And segments such as ethylene-ethyl acrylate copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer, and ethylene-ethyl acrylate-acrylic acid copolymer.

  Specific examples of the olefinic thermoplastic elastomer segment include a mixture of polypropylene and ethylene-propylene copolymer or a cross-linked product thereof, a mixture of polyethylene and ethylene-propylene copolymer or a cross-linked product thereof, and polypropylene and ethylene-propylene. A mixture of non-conjugated polyene copolymer or a cross-linked product thereof, a mixture of polyethylene and ethylene-propylene-non-conjugated polyene copolymer or a cross-linked product thereof, and a hydrogenated product (SEBS) of polypropylene and a styrene-butadiene block copolymer Or a cross-linked product thereof, a mixture of polypropylene and ethylene-1-octene copolymer or a cross-linked product thereof, a mixture of polyethylene and ethylene-1-octene copolymer or a cross-linked product thereof. Crosslinking is performed by a known method, and among them, crosslinking with an organic peroxide is preferable.

  Specific examples of the segment of the styrenic thermoplastic elastomer include styrene-butadiene rubber (SBR) or a hydrogenated product thereof (H-SBR), a styrene-butadiene block copolymer (SBS) or a hydrogenated product thereof (SEBS), Segments such as styrene-isoprene block copolymer (SIS) or its hydrogenated product (SEPS, HV-SIS), styrene- (butadiene / isoprene) block copolymer, styrene- (butadiene / isoprene) random copolymer Can be mentioned.

  Among these segments (a), the ethylene copolymer, olefin thermoplastic elastomer, and styrene thermoplastic elastomer segments are excellent in mechanical properties and are preferably used. Further, when mixed with the resin (c-1), a co-continuous structure can be obtained relatively easily by adjusting the mass ratio, melt viscosity, etc., and the mechanical properties are also good. As the segment (a) of the resin (c-1), an ethylene copolymer segment is preferably used, and in particular, an ethylene- (meth) acrylic acid alkyl ester copolymer or an ethylene-vinyl acetate copolymer. Are most preferably used.

  The segment (b) of the resin (c-1) is a segment composed of at least one vinyl polymer. Here, the vinyl monomer that forms a segment made of a vinyl polymer is a (meth) acrylic acid alkyl ester having an alkyl chain length of 1 to 20 carbon atoms, a vinyl monomer having an acid group, a hydroxyl group. A vinyl monomer having an epoxy group, a vinyl monomer having a cyano group, and at least one monomer selected from styrene. In this specification, acrylic and methacryl are collectively referred to as (meth) acrylic.

  More specifically, this vinyl monomer includes methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, (meth) acrylate-2-ethylhexyl acrylate, (Meth) acrylic acid lauryl, (meth) acrylic acid stearyl, (meth) acrylic acid, maleic acid, maleic anhydride, (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, Meta) Glycidyl acrylate and the like. Among these, since compatibility with the polylactic acid-based resin (B) is relatively good, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid , 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and glycidyl (meth) acrylate are preferred. Furthermore, since a co-continuous structure can be obtained relatively easily by adjusting the mixing ratio, melt viscosity, etc. when mixed with the polylactic acid resin (A), the segment of the resin (c-1) of the present invention ( As b), methyl (meth) acrylate is most preferably used.

  Examples of the copolymer structure of the resin (c-1) include a block copolymer, an alternating copolymer, a random copolymer, and a graft copolymer. The constituting segment (a) and segment (b) The block copolymer and the random copolymer in which the molecular chain ends are connected to each other in a state where the segment (a) and the segment (b) are covalently bonded to each other. It is localized at the phase interface between the compatible polylactic acid resin (A) and the polyolefin resin (B), and functions as a surfactant between the polylactic acid resin (A) phase and the polyolefin resin (B) phase. It is preferable because the formation of large aggregates can be suppressed by reducing the free energy of the interface and increasing the thickness of the interface. In particular, the graft copolymer has a comb-like structure having the segment (a) as a trunk component and the segment (b) as a branch component, and therefore, compared with the block copolymer, the polylactic acid resin (A) phase and the polyolefin Since it is difficult to come out after entering the phase interface with the resin-based resin (B) phase and is easily fixed to the phase interface, the effect of stabilizing the dispersed phase is high and preferable.

  When the resin (c-1) is a graft copolymer, the mass average molecular weight of the vinyl polymer forming the segment (b) [measured by gel permeation chromatography (GPC) in terms of styrene in tetrahydrofuran (THF) Value] is usually in the range of 1,000 to 2,000,000, preferably 5,000 to 1,200,000. If the mass average molecular weight is less than 1,000, the heat resistance of the graft copolymer tends to decrease, and if the mass average molecular weight exceeds 2,000,000, the melt viscosity of the graft copolymer increases. The moldability tends to decrease.

  The melt flow rate (MFR) or melt index (MI) of the resin (c-1) is preferably 0.01 to 500 g / 10 minutes, more preferably 0.1 to 300 g / 10 minutes, and most preferably 1. ~ 200 g / 10 min. This MFR is measured under the conditions of a resin temperature of 230 ° C. and a measurement load of 21 N (2.16 kg-f) in accordance with a method defined in JIS7210. If the MFR is less than 0.01 g / 10 minutes or exceeds 500 g / 10 minutes, the affinity between the graft copolymer and the polylactic acid resin is unfavorable.

  In the resin (c-1), the thermoplastic resin segment (a) is usually 5 to 99% by mass, preferably 20 to 95% by mass, and the vinyl polymer segment (b) is usually 1 to 95% by mass, preferably Is 5 to 80% by mass. When the thermoplastic resin segment (a) is less than 5% by mass or the vinyl polymer segment (b) exceeds 95% by mass, the dispersibility of the resin (c-1) in the polylactic acid resin (A) is lowered. However, the appearance of the resulting molded product tends to be reduced. On the contrary, when the thermoplastic resin segment (a) exceeds 99% by mass or the vinyl polymer segment (b) is less than 1% by mass, the improvement effect on the polylactic acid resin (A) tends to be insufficient. It is in. Based on such a tendency, by adjusting the ratio of the thermoplastic resin segment (a) and the vinyl polymer segment (b) and changing the polarity of the resin (c-1), The interaction with the graft copolymer can be adjusted.

  The production method of the resin (c-1) may be any generally known method such as chain transfer method or ionizing radiation irradiation method, but in the polymer constituting the segment (a), the segment (b) A monomer (monomer) constituting a specific radical, a specific radical (co) polymerizable organic peroxide, a specific radical polymerization initiator are added, and the segment (b) monomer is kneaded in the segment (a) polymer. The production method for carrying out the grafting reaction is simple, the grafting efficiency is high, the secondary aggregation of the segment (b) due to heat does not occur, and the resin (c-1) can be easily mixed with the polylactic acid resin (A). It is preferable because of the excellent interaction between the two.

  As a commercial item of resin (c-1), brand name "Modiper" (made by NOF Corporation), "RESEDA" (made by Toagosei Co., Ltd.), etc. are mentioned, for example.

  Next, the resin (c-2) will be described. Resin (c-2) is selected from the group consisting of vinyl acetate, acrylic acid, (meth) acrylic acid, ethyl (meth) acrylate, methyl (meth) acrylic acid, maleic anhydride, and glycidyl (meth) acrylate. It refers to a copolymer of at least one selected from ethylene and ethylene. Examples of the resin (c-2) include an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer, an ethylene- (meth) acrylic acid copolymer, an ethylene- (meth) acrylic acid ethyl copolymer, Ethylene-vinyl acetate-maleic anhydride copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer, ethylene- (meth) acrylate glycidyl copolymer, ethylene-vinyl acetate- (meth) acrylate glycidyl copolymer And a glycidyl copolymer of ethylene-methyl (meth) acrylic acid- (meth) acrylate. Among them, ethylene-vinyl acetate- (meth) acrylic acid glycidyl copolymer, ethylene-methyl (meth) acrylic acid- (meth) acrylic acid glycidyl copolymer, etc. are mentioned, among them ethylene-vinyl acetate-maleic anhydride Original copolymer, ethylene- (meth) acrylate glycidyl copolymer, ethylene-vinyl acetate- (meth) acrylate glycidyl copolymer, ethylene-ethyl acrylate- (meth) acrylate glycidyl copolymer Can be used.

  The resin (c-2) has an ethylene unit content of 50 to 95% by mass, preferably 60 to 85% by mass. When the ethylene unit content is 50% by mass or more, the rigidity of the entire film can be maintained satisfactorily. On the other hand, when the ethylene unit content is 95% by mass or less, a film having excellent transparency and mechanical strength can be obtained by sufficiently exhibiting the compatibilizing action of the polyolefin resin and the polylactic acid resin.

  As a commercial product of resin (c-2), as an ethylene-vinyl acetate copolymer, a trade name “Evaflex EV40LX” (manufactured by Mitsui-DuPont Polychemical Co., Ltd.), an ethylene-acrylic acid copolymer, a trade name “ NUC copolymer ”(manufactured by Nihon Unicar),“ Evaflex-EEA ”(manufactured by Mitsui-Dupont Polychemical),“ Lex Pearl EAA ”(manufactured by Nippon Polyethylene), ethylene- (meth) acrylic acid copolymer, Trade name “Elvalloy” (Mitsui-DuPont Polychemical Co., Ltd.), “Lex Pearl EMA” (Nihon Polyethylene Co., Ltd.), Ethylene-ethyl acrylate copolymer, Trade name “Lex Pearl EEA” (Nihon Polyethylene Co., Ltd.) As an ethylene-methyl (meth) acrylic acid copolymer, trade name “ACRIFT” As a terpolymer of ethylene-vinyl acetate-maleic anhydride, trade name “Bondaine” (manufactured by Sumitomo Chemical Co., Ltd.), ethylene-glycidyl methacrylate copolymer, ethylene-vinyl acetate-glycidyl methacrylate terpolymer Examples of the ethylene-ethyl acrylate-glycidyl methacrylate terpolymer include trade name “bond first” (manufactured by Sumitomo Chemical Co., Ltd.).

  Next, the resin (c-3) will be described. First, the resin (c-3) is a copolymer of an aromatic hydrocarbon and a conjugated diene hydrocarbon, a hydrogenated product of a copolymer of an aromatic vinyl hydrocarbon and a conjugated diene hydrocarbon, Or it is the copolymer which introduce | transduced the polar group into these.

  As the aromatic hydrocarbon, styrene is preferably used, and styrene homologues such as α-methylstyrene can also be used. As conjugated diene hydrocarbons, 1,3-butadiene, 1,4-butadiene, 1,2-isoprene, 1,4-isoprene, 1,3-pentadiene, etc. are used, and these are hydrogenated derivatives. There may be. These may be used alone or in admixture of two or more.

  In the copolymer of the aromatic hydrocarbon and conjugated diene hydrocarbon or the hydrogenated derivative thereof, the content of the aromatic hydrocarbon is preferably 5 based on the mass of the entire copolymer (100% by mass). It is at least 7 mass%, more preferably at least 7 mass%, even more preferably at least 10 mass%, and preferably at most 50 mass%, more preferably at most 40 mass%, still more preferably at most 35 mass%.

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

  As the aromatic hydrocarbon-conjugated diene hydrocarbon copolymer, each of the above-exemplified copolymers can be used alone or in admixture of two or more. When two or more kinds are mixed and used, the blending ratio is adjusted so that the content of the aromatic hydrocarbon is within the above range as the whole mixed resin.

  Commercially available products of aromatic hydrocarbon-conjugated diene hydrocarbon copolymer include styrene-butadiene block copolymer, trade name “Tufprene” (manufactured by Asahi Kasei Chemical Co., Ltd.), trade name “Asaflex” (Asahi Kasei Chemical) As a hydrogenated derivative of styrene-butadiene block copolymer, trade name “Tuftec H” (Asahi Kasei Chemicals), trade name “Clayton G” (Clayton Japan), styrene-butadiene random copolymer As a hydrogenated derivative, the product name “Dynalon” (manufactured by JSR), as a hydrogenated derivative of a styrene-isoprene block copolymer, the product name “Septon” (manufactured by Kuraray), a styrene-vinylisoprene block copolymer elastomer The product name “Hiblar” (manufactured by Kuraray Co., Ltd.),

  Examples of the polar group introduced into the copolymer of aromatic hydrocarbon and conjugated diene hydrocarbon or a hydrogenated derivative thereof include maleic anhydride-modified SEBS, maleic anhydride-modified SEPS, epoxy-modified SEBS, A typical example is epoxy-modified SEPS. These copolymers can be used alone or in admixture of two or more. When acid modification is performed with maleic anhydride, the amount of maleic anhydride modification is 0.5% by mass or more, preferably 1.0% by mass or more, more preferably 1.5% by mass or more, and 5.0% by mass. % Or less, preferably 4.0% by mass or less, more preferably 3.0% by mass or less. If the amount of maleic anhydride modification is within the above range, a film having excellent transparency and mechanical strength can be obtained by sufficiently exhibiting the compatibilizing action of the polyolefin resin and the polylactic acid resin.

  Specifically, trade names “Tuftec M” (manufactured by Asahi Kasei Chemicals), “Epofriend” (manufactured by Daicel Chemical Industries), etc. are commercially available.

  The content of the compatible resin (C) contained in the layer (II) is 1 part by mass or more, preferably 2 parts by mass or more, with respect to 100 parts by mass of the mixed resin composition containing the polyolefin resin (B) as a main component. More preferably, it is 3 parts by mass or more and 30 parts by mass or less, preferably 25 parts by mass or less, more preferably 20 parts by mass or less. If the content of the compatible resin (C) is 1 part by mass or more with respect to 100 parts by mass of the mixed resin, excellent transparency and impact resistance can be imparted to the film. On the other hand, the rigidity of a film can be maintained by making content of compatible resin (C) into 30 mass parts or less.

  The content of the compatible resin (C) contained in the layer (III) is 1 part by mass or more, preferably 2 parts by mass or more, with respect to 100 parts by mass of the mixed resin composition containing the polyolefin resin (B) as a main component. More preferably, it is 3 parts by mass or more and 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 30 parts by mass or less. If the content of the compatible resin (C) is 1 part by mass or more with respect to 100 parts by mass of the mixed resin, excellent transparency and impact resistance can be imparted to the film.

  In the laminated film of the present invention, the total amount of the resin constituting each layer as an addition amount within a range that does not significantly impair the effects of the present invention, in addition to the above-described components, with respect to any one layer or two or more layers of each layer described above. 0.001 part by mass or more with respect to 100 parts by mass, preferably 0.005 part by mass or more, more preferably 0.01 part by mass or more, and 10 parts by mass or less, preferably 5 parts or less, more preferably 1 Recycled resin, silica, talc, kaolin, carbonic acid generated from trimming loss of film ears, etc., for the purpose of improving and adjusting various properties of the film formability, productivity, and heat-shrinkable film within the range of parts by mass or less. Inorganic particles such as calcium, pigments such as titanium oxide and carbon black, flame retardants, weathering stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, crosslinking agents, lubricants, Agents can be added a plasticizer, an additive such as antioxidant as appropriate.

<Layer structure of film>
If the film of this invention is a thing of the at least 3 layer structure which has a (III) layer between (I) layer and (II) layer, a layer structure will not be specifically limited. Examples include (I) layer / (III) layer / (II) layer, (I) layer / (III) layer / (II) layer / (III) layer / (II) layer, (I) layer / (III ) Layer / (II) layer / (III) layer / (I) layer, (II) layer / (III) layer / (I) layer / (III) layer / (II) layer, and the like. Among them, the more effective laminated structure is (I) layer / (III) layer / (II) layer / (III) layer / (I) layer. By adopting this layer structure, it has the excellent finish that is the object of the invention, has excellent transparency even after regeneration addition, and does not peel off when the label is mounted A heat-shrinkable laminated film suitable for applications such as packaging and shrinkage labels can be obtained with high productivity and economy.

  Next, a film having a five-layer structure of (I) layer / (III) layer / (II) layer / (III) 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% or less, preferably 50% or less, more preferably. 40% or less. The thickness ratio of the (II) layer to the thickness of the entire film is 20% or more, preferably 25% or more, more preferably 30% or more, and the upper limit is 90% or less, preferably 85% or less, and more preferably 80%. % 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, shrink packaging and shrink binding with excellent film stiffness (rigidity at room temperature), shrink finish, transparency at the time of regeneration addition, and delamination of the film are suppressed. A heat-shrinkable laminated film suitable for applications such as packaging and shrinkage labels can be obtained with a good balance.

  The total thickness of the laminated film of the present invention is not particularly limited, but in the case of a stretched film, a thinner one is preferable from the viewpoint of transparency, shrinkage workability, raw material cost, and the like. Specifically, the total thickness of the stretched film is 90 μm or less, preferably 80 μm or less, and more preferably 60 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.

  For example, when the film having a thickness of 50 μm is measured according to JIS K7105, the haze value of the film is preferably 12% or less, and more preferably 10% or less. More preferably, it is 7% or less. If the haze value of the film is 12% or less, the transparency of the film can be obtained and a display effect can be achieved.

  Moreover, the laminated film of the present invention may have at least one printed layer. The printing layer is preferably provided on one surface of the laminated film. In the case of a laminated film, it is preferably provided on the surface of the (I) layer from the viewpoint of improving the followability and solvent resistance of the printed layer during processing. The printed layer is not particularly limited, but in the case of a heat-shrinkable label, which will be described later, when it is applied to the surface on the inner side (that is, the adherend side) when mounted on a container or the like, The print layer is preferred since it does not peel off or become dirty. Moreover, when the transparency of the laminated film is inferior, it is preferably provided on the outer side (that is, the side opposite to the adherend side) from the viewpoint of decorativeness. Furthermore, it may be provided on both surfaces of the heat-shrinkable film.

  The print layer is a layer displaying a product name, an illustration, handling precautions, and the like, and can be formed by a conventional printing method such as gravure printing or flexographic printing. The printing ink used for forming the printing layer is made of, for example, a pigment, a binder resin, a solvent, and other additives. Although it does not specifically limit as said binder resin, For example, resin, such as an acrylic type, a urethane type, a polyamide type, a vinyl chloride-vinyl acetate copolymer type, a cellulose type, a nitrocellulose type, can be used individually or in combination. As the pigment, white pigments such as titanium oxide (titanium dioxide), indigo pigments such as copper phthalocyanine blue, carbon black, aluminum flakes, mica (mica), and other colored pigments can be selected and used in accordance with the application. In addition, extender pigments such as alumina, calcium carbonate, barium sulfate, silica, and acrylic beads can also be used as pigments for the purpose of adjusting gloss. Examples of the solvent include organic solvents such as methyl ethyl ketone, ethyl acetate, methyl alcohol, ethyl alcohol, and isopropyl alcohol, gravure such as water, and flexographic printing ink, and the compatibility and dispersion of each component in the coating agent. Those usually used for the purpose of improving the properties can be used.

  The print layer varies depending on the application and is not particularly limited, but may be a resin layer curable with active energy rays such as visible light, ultraviolet rays, and electron beams. In the case of an active energy ray-curable printing layer, in addition to the above, a photopolymerization initiator such as a photo radical polymerization initiator and a photo cationic polymerization initiator, a sensitizer, etc. should be added to the printing ink. Is preferred.

  In addition to the (I) layer, (II) layer, (III) layer, and printed layer, the laminated film of the present invention is provided with, for example, a coating layer, an anchor coat layer, a primer coat layer, an adhesive layer, and the like. A layer such as a nonwoven fabric, paper, or a metal thin film may be provided as necessary.

<Application>
The laminated film of the present invention can be suitably used as a stretched film because the tensile strength and impact strength are increased by stretching. Moreover, it can also be used as a heat-shrinkable film by adjusting the heat setting temperature after stretching. In addition, it can be suitably used for various molded products.

<Heat shrinkable film>
When the laminated film of the present invention is used as a heat-shrinkable film, it is important that the heat shrinkage rate when immersed in warm water at 80 ° C. for 10 seconds is 20% or more in at least one direction.

  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 a shrinkage label for PET bottles varies depending on the shape, but is generally in the range of 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 sufficiently adhere to the object to be coated within the shrinkage processing time. From these facts, the heat shrinkage rate when immersed in warm water at 80 ° C. for 10 seconds is at least one direction, usually 20% or more in the main shrinkage direction, preferably 30% or more, more preferably 40% or more, The upper limit is 85% or less, preferably 80% or less, and more preferably 75% or less.

  In the heat-shrinkable film, in order to adjust the heat shrinkage rate when immersed in warm water of 80 ° C. for 10 seconds to the above range, the resin composition is adjusted as described in the present invention, and the stretching temperature is described later. It is preferable to adjust to the range. For example, when it is desired to further increase the heat shrinkage rate, the main component is the polyolefin resin (B) which increases the composition ratio of the polyolefin resin (B) constituting the film, increases the draw ratio, lowers the stretching temperature. Means such as providing a component (II) layer may be used.

  Moreover, even when the heat-shrinkable film includes the recycled laminated film of the present invention, the haze value of the film when a film having a thickness of 50 μm is measured according to JIS K7105 is preferably 12% or less, preferably 10%. Hereinafter, it may be more preferably 7% or less. If the haze value of the film after regenerating and adding the recycled laminated film of the present invention is 12% 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.

<Method for producing laminated film>
The laminated 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 shrinks in two directions, such as for overlap, the longitudinal direction is 2 times or more, preferably 3 times or more, and 10 times or less, preferably 6 times or less, and the transverse direction is 2 times. Above, preferably 3 times or more, and 10 times or less, preferably 6 times or less. 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, which is 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. In the case of the film of the present invention, it is generally 50 ° C. or higher, preferably 60 ° C. or higher, and the upper limit is 130. It can be controlled within a range of not higher than ° C, preferably not higher than 110 ° C. 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.

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

  The laminated film of the present invention is processed into a cylindrical shape or the like from a flat shape by an article 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 laminated film and stretched film of the present invention are excellent in film finish, transparency, etc., so the use is not particularly limited, but if necessary, a printing layer, a vapor deposition layer and other functional layers are formed. By doing so, 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 laminated film and stretched film of the present invention have excellent shrinkage characteristics and shrinkage finishing properties, in addition to heat-shrinkable label materials for plastic molded products that cause deformation when heated to high temperatures, the coefficient of thermal expansion, water absorption, etc. However, the material is very different from the heat-shrinkable film of the present invention, such as metal, porcelain, glass, paper, polyolefin resin such as polyethylene, polypropylene, polybutene, polymethacrylate resin, polycarbonate resin, polyethylene terephthalate, polybutylene. It can be suitably used as a heat-shrinkable label material for a package (container) using at least one selected from polyester resins such as terephthalate and polyamide resins as a constituent material.

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

Hereinafter, the present invention will be described in more detail 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 MD (Machine Direction) or the vertical direction, and the perpendicular direction thereof is described as TD (Transverse Direction) or the horizontal direction.

(1) Thermal contraction rate
The obtained film was cut into a size of MD 100 mm and TD 100 mm, dipped in a warm water bath at 80 ° C. for 10 seconds, and then dipped in cold water at 23 ° C. for 30 seconds. The shrinkage rate was calculated by the formula (1).
Shrinkage rate (%) = 100 × (100−A) / 100 (1)

(2) Haze value In accordance with JIS K7105, the haze value of the film was measured at a film thickness of 50 μm and evaluated as x for more than 12%, ◯ for more than 8%, and 、 for 8% or less.

(3) Interlaminar bond strength during shrinkage
The obtained film was cut into a size of MD 165 mm × TD 235 mm, and both ends of the film in the horizontal direction were overlapped by 10 mm and adhered with a solvent in which acetone and ethanol were mixed in half by volume to produce a cylindrical film. This cylindrical film was attached to a cylindrical PET bottle having a capacity of 500 ml, and passed through the steam heating type 3.2 m (3 zones) shrink tunnel for about 5 seconds without rotating. The atmospheric temperature in the tunnel in each zone was controlled in the range of 70 ° C. or more and 90 ° C. or less by adjusting the amount of steam with a steam valve. The state of the film at the time of bottle mounting was confirmed visually and evaluated according to the following criteria.
A: There is no delamination even after the bottle is mounted.
○: Slight delamination occurs at the seal when the bottle is installed.
X: When the bottle is mounted, delamination occurs on the entire seal portion.

(4) Interlaminar peel strength The obtained film was cut into a size of MD15 mm × TD150 mm, only a part of the front and back layers on one side of the TD end face was partially peeled, and the peeled front and back layers and peeled layer were each applied to a chuck of a tensile tester. A 180 degree peel test was performed at a test speed of 50 mm / min with respect to the TD direction. The average value at which the load obtained in the peel test became constant to some extent was evaluated as the delamination strength.

(5) Comprehensive evaluation The heat shrinkage rate is 20% or more, the haze value and the peeled state of the seal part are both ◎, the one containing ○ in either, ○ or both A comprehensive evaluation was given as x when no ◎ was included.

Example 1
As shown in Table 1, as a resin constituting the (I) layer, polylactic acid manufactured by NatureWorks, trade name “NatureWorks NW4060D” (L-form / D-form = 88/12) (hereinafter abbreviated as “PLA1”). ) 60% by mass, polylactic acid manufactured by Mitsui Chemicals, Inc., trade name “Lacia H440” (L / D = 95.75 / 4.25) (hereinafter abbreviated as “PLA2”), 30% by mass, DIC A soft polylactic acid based resin, a product name “Plamate PD-150” (hereinafter abbreviated as “PLA3”) 10% by mass mixed resin, and a resin constituting the (II) layer, manufactured by Ube Industries, Ltd. Linear low density polyethylene, trade name “Umerit 0540F” (hereinafter abbreviated as “PO1”) 50% by mass, polypropylene manufactured by Sumitomo Chemical Co., Ltd., trade name “Nobrene FH3315” , Abbreviated as “PO2”) and 35% by mass of hydrogenated petroleum resin manufactured by Arakawa Chemical Co., Ltd., trade name “Alcon P125” (hereinafter abbreviated as “A1”) 15% by mass. 6 parts by mass of PLA1, 3 parts by mass of PLA2, 1 part by mass of PLA3, ethylene-ethyl acrylate- (meth) acrylate glycidyl copolymer manufactured by Sumitomo Chemical Co., Ltd., trade name “Bond Fast 7M” "(Hereinafter abbreviated as" B1 ") 1 part by mass, modified styrene resin made by JSR, trade name" Dynalon 8630P "(hereinafter abbreviated as" B2 ") 1 part by mass, twin screw extrusion 50% by mass of PLA1 as a resin constituting the layer (III), soft polypropylene manufactured by Dow Chemical Co., Ltd., trade name “Versify 2400” (hereinafter referred to as “III”) is used. , Abbreviated as “PO3”.) 40% by mass, ethylene-ethyl acrylate-methyl methacrylate graft copolymer manufactured by NOF Corporation, trade name “Modiper A5200” (hereinafter abbreviated as “B3”) 10 mass %, And kneaded with a twin-screw extruder, pelletized, and melted and mixed each resin from three Mitsubishi Heavy Industries, Ltd. single-screw extruders at a set temperature of 210 ° C. (I) layer / (III) layer / (II) layer / (III) layer / (I) layer = 30 μm / 5 μm / 180 μm / 5 μm / 30 μm co-extruded from 3 types and 5 layers dies, cast at 50 ° C. It was taken up by a roll and solidified by cooling to obtain an unstretched laminated sheet having a width of 300 mm and a thickness of 250 μm. Next, the film is stretched 5.0 times in the transverse uniaxial direction at a preheating temperature of 80 ° C. and a stretching temperature of 75 ° C. using a film tenter manufactured by Kyoto Machine Co., Ltd., followed by heat treatment at 84 ° C., and a heat-shrinkable laminated film having a thickness of 50 μm. Got. The results of evaluating the obtained film are shown in Table 1.

(Example 2)
The resin composition used in the (III) layer in Example 1 was the same as in Example 1 except that PLA1 was changed to 55% by mass, PO3 was changed to 35% by mass, and B3 was changed to 10% by mass. An unstretched laminated sheet was obtained. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. The results of evaluating the obtained film are shown in Table 1.

(Example 3)
The resin composition used in the (III) layer in Example 1 is the same as in Example 1 except that PLA1 is changed to 60% by mass, PO3 is changed to 30% by mass, and B3 is changed to 10% by mass. An unstretched laminated sheet was obtained. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. The results of evaluating the obtained film are shown in Table 1.

Example 4
The resin composition used in the (III) layer in Example 1 was the same as in Example 1 except that PLA1 was changed to 50% by mass, PO3 was changed to 30% by mass, and B3 was changed to 20% by mass. An unstretched laminated sheet was obtained. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. The results of evaluating the obtained film are shown in Table 1.

(Example 5)
As the constitution of the resin composition used in the (III) layer in Example 1, polylactic acid manufactured by NatureWorks, trade name “NatureWorks NW4032D” (L-form / D-form = 98.5 / 1.5) (hereinafter, “ (Abbreviated as “PLA4”) was changed to 50 mass%, PO3 was changed to 40 mass%, and B3 was changed to 10 mass% to obtain an unstretched laminated sheet in the same manner as in Example 1. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. The results of evaluating the obtained film are shown in Table 1.

(Example 6)
The composition of the resin composition used in the (III) layer in Example 1 was the same as in Example 1 except that PLA4 was changed to 55% by mass, PO3 was changed to 35% by mass, and B3 was changed to 10% by mass. An unstretched laminated sheet was obtained. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. The results of evaluating the obtained film are shown in Table 1.

(Example 7)
The composition of the resin composition used in the (III) layer in Example 1 was the same as in Example 1 except that PLA4 was changed to 60% by mass, PO3 was changed to 30% by mass, and B3 was changed to 10% by mass. An unstretched laminated sheet was obtained. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. The results of evaluating the obtained film are shown in Table 1.

(Example 8)
An unstretched laminated sheet is obtained by the same method as in Example 1 except that PLA1 is changed to 60% by mass and PO3 is changed to 40% by mass as the composition of the resin composition used in the (III) layer in Example 1. It was. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. The results of evaluating the obtained film are shown in Table 1.

Example 9
As a constitution of the resin composition used in the (III) layer in Example 1, PLA1 is 60% by mass, PO1 is 23% by mass, PO2 is 15% by mass, B1 is 1% by mass, and B2 is 1% by mass. An unstretched laminated sheet was obtained in the same manner as in Example 1 except for the change. Next, the film was stretched 5.0 times in the transverse uniaxial direction at a preheating temperature of 80 ° C. and a stretching temperature of 78 ° C. using a film tenter manufactured by Kyoto Machine Co., Ltd., and then heat treated at 90 ° C. to give a heat-shrinkable laminated film having a thickness of 50 μm. Got. The results of evaluating the obtained film are shown in Table 1.

(Comparative Example 1)
The structure of the (III) layer in Example 1 was removed, and the thickness of each layer was (I) layer / (II) layer / (I) layer = 30 μm / 190 μm / 30 μm other than co-extrusion from a two-layer three-layer die. An unstretched laminated sheet was obtained by the same method as in Example 1 except that the above was changed. Next, the film was stretched 5.0 times in the transverse uniaxial direction at a preheating temperature of 80 ° C. and a stretching temperature of 78 ° C. using a film tenter manufactured by Kyoto Machine Co., Ltd., and then heat treated at 90 ° C. to give a heat-shrinkable laminated film having a thickness of 50 μm. Got. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 2)
As a constitution of the resin composition used in the (III) layer in Example 1, a styrene-vinylisoprene block copolymer elastomer “Hiblur 7125” (manufactured by Kuraray Co., Ltd., SIS hydrogenated product; hereinafter abbreviated as “B4”). ) An unstretched laminated sheet was obtained in the same manner as in Example 1 except that the content was changed to 100% by mass. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. Next, the film was stretched 5.0 times in the transverse uniaxial direction at a preheating temperature of 80 ° C. and a stretching temperature of 78 ° C. using a film tenter manufactured by Kyoto Machine Co., Ltd., and then heat treated at 90 ° C. to give a heat-shrinkable laminated film having a thickness of 50 μm. Got. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 3)
An unstretched laminated sheet was obtained in the same manner as in Example 1 except that B1 was changed to 100% by mass as the composition of the resin composition used in the (III) layer in Example 1. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. The results of evaluating the obtained film are shown in Table 2.

(Comparative Example 4)
An unstretched laminated sheet was obtained in the same manner as in Example 1 except that B2 was changed to 100% by mass as the composition of the resin composition used in the (III) layer in Example 1. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. The results of evaluating the obtained film are shown in Table 2.

(Reference Example 1)
An unstretched laminated sheet is obtained by the same method as in Example 1 except that PLA1 is changed to 50% by mass and B3 is changed to 50% by mass as the configuration of the resin composition used in the (III) layer in Example 1. It was. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. The results of evaluating the obtained film are shown in Table 2.

(Reference Example 2)
An unstretched laminated sheet is obtained in the same manner as in Example 1 except that PLA1 is changed to 50% by mass and B1 is changed to 50% by mass as the composition of the resin composition used in the (III) layer in Example 1. It was. Furthermore, this unstretched sheet was stretched by the same method as in Example 1 to obtain a heat-shrinkable laminated film. The results of evaluating the obtained film are shown in Table 2.

From Table 1, the film of Examples 1-9 was a film with favorable haze value, seal part peeling state, and delamination strength. On the other hand, the film of Comparative Examples 1-4 was inferior in any of haze value, a seal part peeling state, and delamination strength (refer Table 2).
This shows that the laminated film of the present invention is a good film that can achieve both transparency and adhesiveness.

Claims (10)

A laminated film comprising at least three layers having a (III) layer between the following (I) layer and (II) layer.
(I) Layer: Resin composition containing polylactic acid resin (A) as a main component (II) Layer: Polylactic acid resin (A) and polyolefin resin (B) Resin composition (III) layer having a content of A) less than the content of polylactic acid resin (A) contained in layer (III): containing polylactic acid resin (A) and polyolefin resin (B) And a resin composition in which the content of the polylactic acid resin (A) is less than the content of the polylactic acid resin (A) contained in the layer (I) The (II) layer, the (III) layer, or the (II) layer and the (III) layer are compatible resins (C) that promote the compatibilization of the polylactic acid resin (A) and the polyolefin resin (B). ), And the compatible resin (C) is at least one selected from the group consisting of the following resin (c-1), resin (c-2), and resin (c-3), and the content thereof The laminated film according to claim 1, wherein the content is 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin composition constituting the (II) layer or the (III) layer.
Resin (c-1): a segment (a) selected from the group consisting of an ethylene homopolymer, an ethylene copolymer, an acid-modified olefin copolymer, an olefin thermoplastic elastomer, and a styrene thermoplastic elastomer , A copolymer having a segment (b) formed from at least one vinyl monomer Resin (c-2): Vinyl acetate, acrylic acid, methacrylic acid, ethyl acrylate, ethyl methacrylate, acrylic acid Copolymer of ethylene with at least one selected from the group consisting of methyl, methyl methacrylate, maleic anhydride, glycidyl acrylate, and glycidyl methacrylate Resin (c-3): Aromatic hydrocarbon and conjugated diene Hydrogenated products of copolymers of aromatic hydrocarbons, copolymers of aromatic vinyl hydrocarbons and conjugated diene hydrocarbons Or copolymers obtained by introducing a polar group thereto The laminated film according to claim 2, wherein a haze value based on JIS K7105 is 12% or less. The laminated film according to any one of claims 1 to 3, wherein the polyolefin resin (B) is a polyethylene resin, a polypropylene resin, or a mixture thereof. The laminated film according to any one of claims 1 to 4, wherein the (II) layer or (III) layer further contains a hydrocarbon resin. A stretched film obtained by stretching the laminated film according to claim 1 in at least one direction. The laminated film according to any one of claims 1 to 5 is stretched in at least one direction, and the thermal shrinkage rate in the main film shrinkage direction when immersed in warm water at 80 ° C for 10 seconds is 20% or more. A heat-shrinkable film. A molded article using the laminated film according to any one of claims 1 to 5, the stretched film according to claim 6, or the heat-shrinkable film according to claim 7 as a base material. A heat-shrinkable label using the heat-shrinkable film according to claim 7 as a substrate. A container equipped with the molded product according to claim 8 or the heat-shrinkable label according to claim 9.