JP2010274611A - Polylactic-acid heat-shrinkable laminated film, molding and heat-shrinkable label using the heat-shrinkable laminated film as base material, and container attached with the molding and the heat-shrinkable label - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-shrinkable laminated film capable of satisfying breaking resistance of a polylactic-acid heat-shrinkable film, and suitable for applications to shrinkage package, shrinkage binding package, a shrinkage label and the like for imparting transparency and a low-temperature shrinkage characteristic. <P>SOLUTION: This heat-shrinkable laminated film is constituted of at least two layers laminated with an A layer comprising a resin composition containing a polylactic acid resin as a main component, and containing core shell type rubber, and a B layer containing a resin composition as a main component comprising the polylactic acid resin, a polyolefin resin, and a prescribed compatibilizing agent, in this order, and has 20% or more of main-shrinkage-directional heat shrinkage rate, when immersed into 80°C of hot water for 10 seconds. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat-shrinkable film suitable for uses such as shrink wrapping, shrink-bound wrapping and a shrinkable label, a molded article and a heat-shrinkable label using the heat-shrinkable film, and the molded article and the label attached thereto. Related to the container.

  Currently, soft drinks such as juice and alcoholic drinks such as beer are sold in a state of being filled in a container such as a bottle or a plastic bottle. At that time, in order to differentiate from other products and improve the visibility of the products, a heat-shrinkable label printed on the outside of the container is attached. As a material for the heat-shrinkable label, polyvinyl chloride (PVC), polystyrene, aromatic polyester or the like is generally used. In addition, from the viewpoint of saving exhaustible resources, labels made of plant-derived raw material plastics are also being studied.

  Among these plant-derived plastics, in particular, polylactic acid resins are made from lactic acid obtained by fermentation of starch, can be mass-produced by chemical engineering, and have excellent transparency and rigidity. As an alternative material of the group polyester (polyethylene terephthalate), it has attracted attention in the field of film packaging materials and injection molding.

  However, a heat-shrinkable film using a polylactic acid-based resin is very brittle, although it is rigid at room temperature, has low-temperature shrinkage, and has good natural shrinkage. There is a problem that shrinkage spots and wrinkles are likely to occur. In addition, the polylactic acid-based heat-shrinkable film also has a problem that when heated, crystallization proceeds and sufficient heat-shrinkage characteristics cannot be obtained.

  As means for solving the above problem, a film in which the copolymerization ratio of L-lactic acid and D-lactic acid in a polylactic acid resin is adjusted is known (see Patent Document 1). However, although this film can suppress crystallization during heating, the problem of causing spots, wrinkles, and avatars due to rapid shrinkage cannot be sufficiently solved.

  In addition, attempts have been made to improve shrink finish by adjusting the crystallinity of the polylactic acid resin and further blending an aliphatic polyester resin (see Patent Document 2). However, compared to PVC heat-shrinkable films, it is still difficult to say that the shrink finish is sufficient.

  Furthermore, since the polylactic acid-based resin is brittle, the material itself has a problem that when it is molded into a single sheet or film, sufficient strength cannot be obtained and it is difficult to put it into practical use.

  Containing an aliphatic polyester other than polylactic acid (see Patent Document 3), polycaprolactone (see Patent Document 4), a copolymer polyolefin such as an ethylene-vinyl acetate copolymer (see Patent Document 5), etc. The method of making it known is known. These mainly have the purpose of improving brittleness while maintaining the transparency of the polylactic acid-based resin film, and there still remains an insufficient point with respect to shrink finish.

  Furthermore, as a technique for improving the brittleness of the polylactic acid-based resin, a film made of polylactic acid and a polyolefin compound (see Patent Document 6), a molded product made of polylactic acid and a modified olefin compound (see Patent Document 7) or a composition ( Patent Document 8), a molded product made of polylactic acid and syndiotactic polypropylene (see Patent Document 9), a polymer mainly composed of lactic acid, an aliphatic carboxylic acid, and an aliphatic mainly composed of a chain molecular diol. A plasticized polylactic acid film made of a polyester plasticizer (see Patent Document 10), a biodegradable resin composition made of polylactic acid and an epoxidized diene block copolymer (see Patent Document 11), polylactic acid, Lactic acid polymer composition (patent document 12) comprising aliphatic polyester and polycaprolactone, crystalline polylactic acid, and natural rubber And polylactic acid resin composition comprising at least one rubber component selected from polyisoprene methods using (Patent Document 13) have been disclosed.

  However, when the above polycaprolactone, modified olefin compound, epoxidized diene block copolymer, natural rubber, polyisoprene, etc. are mixed with lactic acid resin, the impact resistance is improved, but as a result, transparency For example, it is difficult to say that the technique is sufficient for use in applications where it is necessary to check contents such as packaging materials.

  In addition, a polyacetal resin and diene rubber, natural rubber, silicone rubber, polyurethane rubber, or a multilayer structure having a core layer containing at least one selected from a styrene unit and a butadiene unit in a shell layer of methyl (meth) acrylate. A technique for improving impact resistance by blending an impact modifier with a polylactic acid resin is known (see Patent Document 14), but it is not sufficient as a heat shrinkable film.

  Furthermore, a technique (see Patent Document 15) for blending a polylactic acid resin with a graft copolymer obtained by graft polymerization of a rubber polymer and a vinyl monomer has been proposed. Not enough.

  In addition, in a resin composition containing an aliphatic polyester and a multilayer structure polymer, a technique (see Patent Document 16) in which tensile elongation and impact resistance are improved has been proposed. In view of the above, the shrink film undergoes a printing process and a bag making process after film formation. In gravure printing, which is a general printing method, printing is performed through many rolls and printing is performed at a high speed for the purpose of improving productivity. It was clarified by implementation verification that the required fracture resistance was insufficient.

JP 2003-119367 A JP 2001-11214 A JP-A-9-169896 JP-A-8-300481 JP-A-9-151310 JP 2005-68232 A JP 9-316310 A Japanese Patent Laid-Open No. 5-179110 JP-A-10-251498 JP 2000-191895 A JP 2000-219803 A JP 2001-31853 A JP 2003-183488 A JP 2003-286400 A JP 2004-285258 A JP 2003-286396 A

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to satisfy shrinkage resistance of a polylactic acid-based heat-shrinkable film and to provide transparency and low-temperature shrinkage characteristics, and shrinkage binding. The object is to obtain a heat-shrinkable film suitable for applications such as packaging and shrinkage labels.

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

As a result of diligent research on the blending of a polylactic acid-based resin, a core-shell type rubber, a polyolefin-based resin, and a compatibilizing agent, the present inventors have found that heat shrinkability that can satisfy various properties such as fracture resistance, transparency, and low temperature shrinkability. The present invention was completed by successfully producing a laminated film.
That is, an object of the present invention is to provide an A layer (provided that the A layer is the outermost layer) composed of a polylactic acid resin as a main component and containing a core-shell type rubber, a polylactic acid resin, and a polyolefin resin. A laminated film composed of at least two layers in which a B layer mainly composed of a resin composition comprising a resin and a compatibilizing agent is laminated in this order, wherein the compatibilizing agent is an ethylene-α olefin copolymer Rubber, ethylene-α-olefin-nonconjugated polyene copolymer rubber, ethylene- (meth) acrylic acid alkyl ester copolymer, ethylene-vinyl acetate copolymer, olefin-based thermoplastic elastomer, and styrene-based thermoplastic elastomer A vinyl polymer formed from at least one vinyl monomer having a thermoplastic resin segment selected from the group as a trunk component A graft copolymer having a segment as a branch component, wherein the laminated film is stretched in at least one direction and has a heat shrinkage ratio of 20% or more in the main shrinkage direction when immersed in warm water at 80 ° C. for 10 seconds. This is achieved by a shrinkable laminated film (hereinafter referred to as the first invention).

  In the first invention, the core-shell type rubber preferably has a shell made of (meth) acrylic acid ester and a core made of silicone rubber or acrylic rubber.

  1st invention WHEREIN: It is preferable that the content rate of a core-shell type rubber is 3 to 30 mass% with respect to 100 mass% of the resin composition which comprises A layer.

  1st invention WHEREIN: The polylactic acid-type resin contained in B layer is 60 to 89 mass% with respect to 100 mass% of the whole resin composition which comprises B layer, and polyolefin resin is 10 mass%. It is preferable that it is 40 mass% or less, and a compatibilizer is 1 mass% or more and 15 mass% or less.

  The second invention is a molded article using the heat-shrinkable laminated film of the first invention as a base material.

  The third invention is a heat-shrinkable label using the heat-shrinkable laminated film of the first invention as a substrate.

  The fourth invention is a container equipped with the molded product of the second invention or the heat-shrinkable label of the third invention.

  According to the first invention, the outermost layer has an A layer formed of a mixed resin containing a polylactic acid-based resin and a core-shell type rubber in a predetermined ratio, and the polylactic acid-based resin and the polyolefin-based resin are combined with each other. Since it has at least two layers of the B layer composed of a mixed resin with a solubilizing agent, it becomes a heat shrinkable film excellent in fracture resistance, transparency and low temperature shrinkage characteristics.

  Furthermore, according to the second to fourth inventions, a molded product and a heat-shrinkable label using the heat-shrinkable film suitable for applications such as shrink-wrapping, shrink-bound packaging and shrink-labeling, and the molded product or the heat A container equipped with a shrinkable label can be provided.

  Hereinafter, the first to fourth inventions of the present application will be described in detail.

  In the present specification, “main component” is intended to allow other components to be included as long as the action and effect of the resin constituting each layer is not hindered. Further, this term does not limit the specific content, but it is 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and 100% by mass, based on the total components of each layer. It is a component occupying the range of% or less.

[First invention]
The first invention is mainly composed of a resin composition comprising a polylactic acid-based resin as a main component and a layer A composed of a resin composition containing a core-shell rubber, a polylactic acid-based resin, a polyolefin-based resin, and a compatibilizing agent. Is a heat-shrinkable laminated film composed of at least two layers laminated in this order. In the first invention, it is sufficient that the A layer and the B layer each have one or more layers, and the A layer is disposed as the outermost layer.

<A layer>
1st invention has A layer which consists of a resin composition which has polylactic acid-type resin as a main component and contains core-shell type rubber | gum as an outermost layer.

(Polylactic acid resin)
The polylactic acid resin used in the A layer of the first invention is a homopolymer of D-lactic acid or L-lactic acid, or a copolymer thereof, and specifically, the structural unit is D-lactic acid. There are poly (D-lactic acid), poly (L-lactic acid) whose structural unit is L-lactic acid, and poly (DL-lactic acid) which is a copolymer of L-lactic acid and D-lactic acid, and D- A mixed resin of a plurality of the above copolymers having different copolymerization ratios of lactic acid and L-lactic acid is also included.

  The copolymer of L-lactic acid and D-lactic acid preferably has a copolymerization ratio of D-lactic acid and L-lactic acid (hereinafter abbreviated as “D / L ratio”) of “3/97” to “15/85” or “85/15” to “97/3”, more preferably “5/95” to “15/85” or “85/15” to “95/5”, and “8/92” to “15/85” or “85/15” to “92/8” is preferable, and “10/90” to “15/85” or “85/15” to “85” is particularly preferable. 90/10 ".

  When the copolymerization ratio of D-lactic acid is higher than 97 or less than 3, high crystallinity is exhibited, the melting point is high, and heat resistance and mechanical properties tend to be excellent. However, when used as a heat-shrinkable film, it usually involves printing and a bag-making process using a solvent, so that the crystallinity of the constituent material itself can be lowered appropriately in order to improve printability and solvent sealability. Necessary. Moreover, when crystallinity is too high, orientation crystallization advances at the time of extending | stretching, and there exists a tendency for the film shrinkage | contraction characteristic at the time of heating to fall. Furthermore, even if the film has crystallization suppressed by adjusting the stretching conditions, crystallization proceeds prior to shrinkage due to heating during heat shrinkage, and as a result, there is a tendency to cause shrinkage unevenness or insufficient shrinkage.

  On the other hand, when the copolymerization ratio of D-lactic acid is less than 85 or higher than 15, the crystallinity is almost completely lost. As a result, when the labels collide with each other after heat shrinkage, they are fused by heat. Troubles such as end up occur easily. Therefore, by adjusting the composition ratio of D-lactic acid and L-lactic acid in the polylactic acid resin within the above range, it is possible to obtain a heat-shrinkable film having excellent shrinkage characteristics that does not cause the problems described above. Become.

  In the first invention, it is possible to blend polylactic acid resins having different D / L ratios, and blending is more preferable because the D / L ratio of the polylactic acid resins can be adjusted more easily. . In this case, the average value of the D / L ratios of a plurality of lactic acid polymers may be set within the above range. By blending two or more polylactic acid resins having different D / L ratios and adjusting the crystallinity according to the intended use, it is possible to balance heat resistance and heat shrinkage characteristics.

  In addition, the polylactic acid resin is a non-aliphatic non-aliphatic acid such as α-hydroxycarboxylic acid other than lactic acid, terephthalic acid, etc. At least one selected from the group consisting of aliphatic dicarboxylic acids such as dicarboxylic acids and succinic acids, non-aliphatic diols such as ethylene oxide adducts of bisphenol A, and aliphatic diols such as ethylene glycol can be used. For the purpose of increasing the molecular weight, a small amount of a chain extender such as a diisocyanate compound, an epoxy compound, or an acid anhydride can be used.

  Examples of α-hydroxycarboxylic acid units other than lactic acid include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, and 2-hydroxy-3- Examples thereof include bifunctional aliphatic hydroxycarboxylic acids such as methylbutyric acid, 2-methyllactic acid, and 2-hydroxycaproic acid, and lactones such as caprolactone, butyrolactone, and valerolactone.

  Examples of the diol unit include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like. Examples of the dicarboxylic acid unit include succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanedioic acid.

  The copolymerization ratio in the copolymer of lactic acid and α-hydroxycarboxylic acid other than lactic acid is not particularly limited, but the higher the proportion of lactic acid, the less the consumption of petroleum resources, which is preferable, and the Vicat softening point described later It is preferable to carry out copolymerization at a ratio not exceeding the range. Specifically, the copolymerization ratio of lactic acid and a copolymer of α-hydroxycarboxylic acid other than lactic acid, aliphatic diol, or aliphatic dicarboxylic acid is α-hydroxycarboxylic acid other than lactic acid / lactic acid, aliphatic diol, Or aliphatic dicarboxylic acid = “95/5” to “10/90”, preferably “90/10” to “20/80”, and more preferably “80/20” to “30/70”. 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. Moreover, as a structure of these copolymers, a random copolymer, a block copolymer, and a graft copolymer are mentioned, Any structure may be sufficient. However, a block copolymer or a graft copolymer is preferable from the viewpoint of impact resistance and transparency of the film.

  The weight (mass) average molecular weight of the polylactic acid-based resin 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 or less. More preferably, it is 300,000 or less. When the weight (mass) average molecular weight 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. 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.

  As the polymerization method of the polylactic acid-based resin, a known method such as a condensation polymerization method or a ring-opening polymerization method can be employed. 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.

  A typical example of the polylactic acid resin preferably used in the first invention is “Nature Works” manufactured by Nature Works LLC, and the like. Specific examples of the random copolymer of PLA resin, diol, and dicarboxylic acid include, for example, “GS-Pla” (manufactured by Mitsubishi Chemical Corporation), and specific examples of the block copolymer include, for example, “Plamate” (manufactured by DIC) can be mentioned.

<Core shell type rubber>
The core-shell type rubber used in the A layer of the first invention is a polymer composed of a core layer and one or more shell layers covering the core layer. The number of shell layers used in the A layer of the film of the present invention is not particularly limited, and may be two or more.

  As the core layer of the core-shell type rubber, those having rubber elasticity are preferable for improving fracture resistance. For example, acrylic, silicone, styrene, nitrile, conjugated diene, urethane, and olefin polymers. Etc. Of these, silicone rubber and acrylic rubber are preferable as the core layer from the viewpoint of transparency, which is one of the required properties of the shrink film. Specific examples thereof include a rubber component formed by polymerizing a siloxane compound such as dimethylsiloxane and phenylmethylsiloxane, an acrylic compound such as ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, or a combination of these components. Polymerization components and the like are also preferable.

  As the shell layer forming the outermost layer of the core-shell rubber, the shell is an unsaturated carboxylic acid ester unit, a glycidyl group-containing vinyl unit, an aliphatic vinyl unit, an aromatic vinyl unit, a vinyl cyanide unit, Examples thereof include polymers containing a maleimide unit, an unsaturated dicarboxylic acid anhydride unit, or other vinyl units. Among these, a polymer containing a (meth) acrylic acid ester unit is preferable from the viewpoint of compatibility with the polylactic acid resin.

  The method for producing the core-shell type rubber is not particularly limited, and can be obtained by a known polymerization method, for example, suspension polymerization, emulsion polymerization or the like including a mixture containing a monomer and a polyfunctional vinyl monomer in a specific ratio.

  The content of the core-shell type rubber is 3% by mass or more, preferably 5% by mass or more, more preferably 7% by mass or more, based on the mass (100% by mass) of the entire resin composition constituting the A layer. 30% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less.

  When the content of the core-shell rubber is 3% by mass or more, the rupture resistance of the A layer is improved, and even in the film of the present invention having a laminated structure, the entire laminated film can be obtained by improving the rupture resistance of the A layer. Can be suppressed, and a tensile elongation at break sufficient for the required quality as a shrink film can be obtained. Moreover, if the addition amount of the core-shell type rubber is 30% by mass or less, peeling between layers of the A layer and the B layer described later does not occur, so that handling in the printing process and the bag making process is good.

  The equivalent circle diameter of the core-shell type rubber is not particularly limited, but is 0.01 μm or more, preferably 0.02 μm or more, more preferably 0.05 μm or more, 100 μm or less, preferably 50 μm or less, Preferably it is 20 micrometers or less. If the equivalent circle diameter of the core-shell type rubber is 0.01 μm or more, it is preferable because it is sufficient to exhibit a fracture resistance effect. If the equivalent circle diameter is 100 μm or less, it is added to the A layer forming the outermost layer. In this case, there is little increase in external haze due to surface roughness, etc., and even when printing is performed on the film of the present invention to improve the design, there are also disadvantages such as ink loss is difficult to occur and the appearance of the printed design is impaired. Less preferred.

  The mass ratio between the core and the shell of the core-shell type rubber is not particularly limited, but the core layer is 20 parts by mass or more, preferably 30 parts by mass or more, more preferably 50, based on the whole multilayer structure polymer. It is not less than 95 parts by mass, preferably not more than 90 parts by weight, and more preferably not more than 85 parts by mass. If the core layer is 20 parts by weight or more, it is preferable because the fracture resistance effect when added to the A layer can be maintained.

  Examples of commercially available core-shell type rubbers include “Metabrene” (manufactured by Mitsubishi Rayon Co., Ltd.), “Kane Ace” (manufactured by Kaneka Chemical Co., Ltd.), “Paraloid” (manufactured by Kureha Chemical Industry Co., Ltd.), “Acryloid” (ROHM) And Haas), “Stuffyroid” (Takeda Pharmaceutical Co., Ltd.), “Parapet SA” (Kuraray Co., Ltd.) and the like.

<B layer>
The B layer of the first invention is mainly composed of a resin composition comprising a polylactic acid resin, a polyolefin resin, and a compatibilizer. Moreover, it is preferable that B layer is an inner layer so that it may demonstrate later.

(Polylactic acid resin)
The polylactic acid resin used in the B layer can be the same as that in the A layer described above.

(Polyolefin resin)
The polyolefin resin used in the first invention has a storage elastic modulus (E ′) at 20 ° C. of 100 MPa or less, preferably 80 MPa or less, more preferably when measured under conditions of a vibration frequency of 10 Hz and a strain of 0.1%. Is 50 MPa or less. The lower limit value of the storage elastic modulus (E ′) is 0.1 MPa or more, preferably 1.0 MP or more, more preferably 3.0 MPa or more in consideration of the waist (rigidity at room temperature) of the entire film. The polyolefin-based resin having a storage elastic modulus (E ′) of 20 ° C. of the first invention within the above range has a low crystallinity of the polyolefin and a low density, so the average refractive index of the polyolefin-based resin is also low, The average refractive index with the polylactic acid resin to be mixed can be made closer. Therefore, since the internal haze of the first invention can be reduced, it is very useful in improving fracture resistance and maintaining transparency. Moreover, if storage elastic modulus (E ') is 100 Mpa or less, the improvement effect of fracture resistance will not fall, and generation | occurrence | production of a significant external appearance defect can be suppressed. On the other hand, if the storage elastic modulus (E ′) of the first invention is 0.1 MPa or more, it is possible to prevent the waist of the whole film from being significantly lowered.

Further, the polyolefin resin has a storage elastic modulus (E ′) at 70 ° C. of 50 MPa or less, preferably 30 MPa or less, more preferably 20 MPa or less, and further preferably 10 MPa or less when measured at a vibration frequency of 10 Hz. On the other hand, the lower limit value of the storage elastic modulus (E ′) is 0.1 MPa or more, preferably 0.5 MPa or more, and more preferably 1.0 MPa or more. When the first invention is used for shrinkage labeling of PET bottles, etc., a heat shrinking process is required as a label attachment process on a covering object such as a PET bottle. Moreover, in order to prevent the content from deteriorating, bursting, etc., the heat shrinking process is performed at 60 to 100 ° C. Therefore, if the storage elastic modulus (E ′) at 70 ° C. of the polyolefin resin used in the first invention is 50 MPa or less, the film can exhibit a sufficient heat shrinkage rate in the heat shrink processing temperature region. it can. Further, if the storage elastic modulus (E ′) at 70 ° C. is 0.1 MPa or more, sufficient film strength can be maintained in the heat shrinking process, so that the film is not broken or twisted. It is easy to enable uniform attachment to the object.
In addition, the storage elastic modulus (E ′) of the polyolefin resin is such that the vibration frequency is 10 Hz, the strain is 0.1%, the temperature rising rate is 2 ° C./min, and the chuck is 2.5 cm at temperatures of 20 ° C. and 70 ° C. The dynamic viscoelasticity can be calculated in the range of −150 ° C. to 200 ° C.

  1st invention WHEREIN: The magnitude | size of the said storage elastic modulus (E ') can be adjusted by increasing / decreasing content of the copolymer of the below-mentioned ethylene and C3-C20 alpha olefin. it can. For example, when it is desired to increase the storage elastic modulus (E ′), the content of a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms is reduced, or in the copolymer with an α-olefin. In the case of reducing the copolymerization ratio of α-olefin and reducing the storage elastic modulus (E ′), the content of the copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms is increased, or It can be adjusted by increasing the copolymerization ratio of the α-olefin in the copolymer with the α-olefin.

  In the first invention, if the polyolefin-based resin used has a storage elastic modulus (E ′) at 20 ° C. measured under the conditions of a vibration frequency of 10 Hz and a strain of 0.1% satisfying the range described above. Although not particularly limited, from the viewpoint of adjusting the storage elastic modulus (E ′) at 70 ° C. to a predetermined range, and from the viewpoint of heat shrinkage characteristics, mechanical properties, and moldability, a polyethylene resin, a polypropylene resin, or It is preferable to use a mixture thereof.

  Examples of preferred polyethylene resins and polypropylene resins used in the first invention are shown below.

  Examples of polyolefin resins used in the first invention include polyethylene resins, polypropylene resins, ethylene copolymers such as ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, and ethylene-methyl acrylate copolymers. A polymer is mentioned. Especially, it is preferable to use a polyethylene-type resin, a polypropylene-type resin, or these mixtures from a viewpoint of a heat shrinkage rate and a moldability. There are various types of polyethylene resins and polypropylene resins depending on the polymerization method and copolymerization component, and the range is not particularly limited. Preferred types are shown below.

The polyethylene resin used in the first invention is a medium density polyethylene resin (MDPE) having a density of 0.92 g / cm ³ or more and 0.94 g / cm ³ or less, and a low density having a density of less than 0.92 g / cm ^3. A polyethylene resin (LDPE) and a linear low density polyethylene resin (LLDPE) are mentioned. Among these, linear low density polyethylene resin (LLDPE) is particularly preferably used from the viewpoint of stretchability, impact resistance of the film, transparency, and the like.

  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. Among 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.

  In the first invention, the polyolefin-based resin contains a polyethylene component, and the content thereof is preferably 70% by mass or more, and more preferably 75% by mass or more. If it is 70 mass% or more, the whole film can be maintained.

In particular, in the first invention, it is preferable that the density of the polyethylene resin is 0.910 g / cm ³ or less, more preferably 0.905 g / cm ³ or less, more preferably 0.900 g / cm ³ or less. Moreover, although a minimum is not specifically limited, 0.800 g / cm < ³ > or more is preferable, 0.850 g / cm < ³ > or more is more preferable, 0.880 g / cm < ³ > or more is more preferable. If the density is 0.910 g / cm ³ or less, the affinity with polylactic acid is also improved, the stretchability is maintained, and a sufficient heat shrinkage rate in the practical temperature range (about 70 ° C. or more and about 90 ° C. or less) can be obtained. preferably in that it can, on the other hand, since the density of 0.800 g / cm ³ or more value, if the film (stiffness at room temperature) across the waist and not significantly reduce the heat resistance, practically preferable.

  As the polyethylene resin, those having a melt flow rate (MFR: JIS K7210, temperature: 190 ° C., load: 21.18 N) of 0.1 g / 10 min to 10 g / 10 min are preferably used. When the MFR is 0.1 g / 10 min or more, the extrudability can be maintained satisfactorily. On the other hand, when the MFR is 10 g / 10 min or less, the thickness unevenness of the laminated film and the mechanical strength are hardly lowered, which is preferable.

  Next, as the polypropylene resin used in the first invention, in addition to the homopropylene resin, a soft polypropylene resin having flexibility as compared with the homopropylene resin can be used. Examples of the soft polypropylene resin include random polypropylene resin, block polypropylene resin, and propylene-ethylene rubber. Among these, a random polypropylene resin is particularly preferably used from the viewpoints of stretchability and fracture resistance.

  In the random polypropylene resin, the α-olefin to be copolymerized with propylene preferably includes those having 2 to 20 carbon atoms, more preferably those having 4 to 12 carbon atoms, such as ethylene, 1-butene, 1-pentene. 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and the like. In the film of the present invention, the content of propylene units as an α-olefin is 80% by mass or more, preferably 85% by mass or more from the viewpoints of stretchability, heat shrinkage properties, film impact resistance, transparency, rigidity and the like. More preferably, 90% by mass or more of random polypropylene is particularly preferably used. Moreover, you may use the alpha olefin to copolymerize individually by 1 type or in combination of 2 or more types.

  The melt flow rate (MFR) of the polypropylene resin is usually 0.5 g / 10 min or more, preferably 1.0 g / 10 min, with MFR (JIS K7210, temperature: 230 ° C., load: 21.18 N). It is above, and it is desirable that it is 15 g / 10 min or less, preferably 10 g / 10 min or less.

  More specifically, these polyethylene resins and polypropylene resins are trade names “Novatech LD, LL”, “Kernel”, “Toughmer A, P” (manufactured by Nippon Polytech Co., Ltd.), “Suntech HD, LD” as polyethylene resins. ”(Asahi Kasei Chemicals),“ HIZEX ”“ ULTZEX ”“ EVOLUE ”(Mitsui Chemicals),“ Moretech ”(Idemitsu Kosan),“ UBE polyethylene ”“ UMERIT ”(Ube Industries),“ NUC ” It is commercially available as “polyethylene”, “Nackflex” (manufactured by Nihon Unicar), “engage” (manufactured by Dow Chemical). These resins can be used alone or in admixture of two or more.

  Also, as polypropylene resins, the trade names “NOVATEC PP”, “WINTEC”, “Toughmer XR” (manufactured by Nippon Polypro), “Mitsui Polypro” (manufactured by Mitsui Chemicals), “Sumitomo Noblen”, “Tough Selenium”, “Excellen EPX” (Sumitomo Chemical) ), “IDEMITSU PP”, “IDEMITSU TPO” (manufactured by Idemitsu Kosan Co., Ltd.), “Adflex”, “Adsyl” (manufactured by Sun Allomer), “VERSIFY” (manufactured by Dow Chemical Co., Ltd.), and the like. These resins can be used alone or in admixture of two or more.

  In the first invention, a copolymer of the above-mentioned monomer copolymerizable with ethylene can also be suitably used as the polyolefin resin. Examples of the copolymer of a monomer copolymerizable with ethylene include an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-methyl acrylate copolymer.

  The ethylene content of the ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer is 70% by mass or more, preferably 75% by mass or more, and 95% by mass or less, preferably Is preferably 90% by mass or less, more preferably 85% by mass or less. If ethylene content rate is 70 mass% or more, the fracture resistance and shrinkage | contraction characteristic of the whole film can be maintained favorable.

  Examples of commercially available ethylene-vinyl acetate copolymer (EVA) include “Evaflex” (manufactured by Mitsui DuPont Polychemical Co., Ltd.), “Novatech EVA” (manufactured by Mitsubishi Chemical Corporation), and “Ebaslene” (manufactured by DIC Corporation). , “Evertate” (manufactured by Sumitomo Chemical Co., Ltd.). Moreover, as a commercial item of an ethylene / ethyl acrylate copolymer (EEA), for example, “Evaflex EEA” (manufactured by Mitsui DuPont Polychemical Co., Ltd.), and as an ethylene / methyl acrylate copolymer, “Elvalloy AC” (Mitsui DuPont Poly) is used. Chemical Co., Ltd.). These copolymers can be used alone or in admixture of two or more.

  The MFR of the copolymer of the copolymerizable monomer with ethylene is not particularly limited, but usually MFR (JIS K7210, temperature: 190 ° C., load: 21.18 N) is preferably the lower limit. 0.5 g / 10 min or more, more preferably 1.0 g / 10 min or more, and the upper limit is preferably 15 g / 10 min or less, more preferably 10 g / 10 min or less.

  In the polyolefin resin used in the first invention, the lower limit of the mass average molecular weight is preferably 50,000 or more, more preferably 100,000 or more, and the upper limit is 700,000 or less, more preferably 600, 000 or less, more preferably 500,000 or less. When the mass average molecular weight of the polyolefin resin is within the above range, practical physical properties such as desired mechanical properties and heat resistance can be expressed, an appropriate melt viscosity can be obtained, and good moldability can be obtained.

  The method for producing the polyolefin resin 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.

(Compatibilizer)
In the first invention, the compatibilizing agent is mainly composed of a resin that compatibilizes the polylactic acid resin and the polyolefin resin. The compatibilizing agent is not particularly limited as long as it is a resin that compatibilizes a polylactic acid resin and a polyolefin resin, but ethylene-α olefin copolymer rubber, ethylene-α olefin-nonconjugated polyene copolymer rubber, ethylene -A thermoplastic resin segment selected from the group consisting of (meth) acrylic acid alkyl ester copolymers, ethylene-vinyl acetate copolymers, olefinic thermoplastic elastomers, and styrene thermoplastic elastomers as a main component, and at least one kind It is preferable to use a graft copolymer having a vinyl polymer segment formed from a vinyl monomer as a branch component.

  The thermoplastic resin used for the thermoplastic resin segment which is the main component of the graft copolymer is ethylene-α olefin copolymer rubber, ethylene-α olefin-nonconjugated polyene copolymer rubber, ethylene- (meth) acrylic acid. It is selected from the group consisting of an alkyl ester copolymer, an ethylene-vinyl acetate copolymer, an olefin-based thermoplastic elastomer, and a styrene-based thermoplastic elastomer. These may be used alone or in combination of two or more.

  Examples of the α-olefin other than ethylene of the ethylene-α olefin copolymer rubber and the ethylene-α olefin-nonconjugated polyene copolymer rubber include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1 -Decene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, 5-methyl-1-hexene and the like can be mentioned. 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), 8-methyl-4-ethylidene-1,7-nonadiene, 4-ethylidene-1,7-undecadiene (above, chain triene), etc. Can be mentioned.

  Specific examples of the ethylene-α olefin copolymer rubber include ethylene-propylene copolymer rubber, ethylene-butene copolymer rubber, ethylene-hexene copolymer rubber, ethylene-octene copolymer rubber, and the like.

  Specific examples of the ethylene-α olefin-nonconjugated polyene copolymer rubber include ethylene-propylene-ethylidene norbornene copolymer rubber, ethylene-propylene-dicyclopentadiene copolymer rubber, ethylene-butene-5-ethylidene. -2-norbornene copolymer rubber.

  Specific examples of the ethylene- (meth) acrylic acid alkyl ester copolymer include ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-n-butyl acrylate copolymer, ethylene-acrylic. Acid isobutyl copolymer, ethylene-acrylic acid 2-ethylhexyl copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-n-butyl methacrylate copolymer, ethylene-methacrylic acid An isobutyl copolymer, an ethylene-methacrylic acid 2-ethylhexyl copolymer, etc. are mentioned.

  Commercially available ethylene- (meth) acrylic acid alkyl ester copolymers are ethylene-ethyl acrylate copolymers, trade names “Lex Pearl EEA” (manufactured by Nippon Polyethylene), “Evaflex-EEA” (Mitsui Examples of the ethylene-methyl (meth) acrylic acid copolymer include DuPont Polychemical Co., Ltd., and trade names “Acryft” (manufactured by Sumitomo Chemical Co., Ltd.), “Nucrel” (manufactured by Mitsui DuPont Polychemical Co., Ltd.), and the like. Examples of commercially available ethylene-vinyl acetate copolymers include “Evaflex” (manufactured by Mitsui DuPont Polychemical Co., Ltd.) and “Novatech EVA” (manufactured by Nippon Polyethylene Co., Ltd.).

  Specific examples of the olefinic thermoplastic elastomer include a blend of polypropylene and ethylene-propylene copolymer rubber or a crosslinked product thereof, a blend of polyethylene and ethylene-propylene copolymer rubber or a crosslinked product thereof, and polypropylene and ethylene. -Propylene-nonconjugated polyene copolymer rubber blend or cross-linked product thereof, polyethylene-ethylene-propylene-nonconjugated polyene copolymer rubber blend product or cross-linked product thereof, polypropylene and styrene-butadiene block copolymer A blend of rubber with hydrogenated product (SEBS) or a cross-linked product thereof, a blend of polypropylene and ethylene-1-octene copolymer rubber or a cross-linked product thereof, polyethylene and ethylene-1-octene copolymer rubber And blends or cross-linked products thereof That. Crosslinking is performed by a known method, and among them, crosslinking with an organic peroxide is preferable.

  These olefin-based thermoplastic elastomers are already on the market, for example, trade name “Mirastomer” (manufactured by Mitsui Chemicals), trade name “Santoprene” (manufactured by AES Japan), trade name “Sumitomo TPE”. "(Sumitomo Chemical Co., Ltd.), trade name" Engege "(DuPont Dow Elastomer Co., Ltd.), trade name" Thermo Run "(Mitsubishi Chemical Co., Ltd.), and the like.

  Specific examples of the styrenic thermoplastic elastomer include styrene-butadiene rubber (SBR) or its hydrogenated product (H-SBR), styrene-butadiene block copolymer rubber (SBS) or its hydrogenated product (SEBS), styrene. -Isoprene block copolymer rubber (SIS) or its hydrogenated product (SEPS, HV-SIS), etc. are mentioned. The styrenic thermoplastic elastomers are also commercially available, for example, trade name “Tuftec” (manufactured by Asahi Kasei Co., Ltd.), trade name “elastomer AR” (manufactured by Aron Kasei Co., Ltd.), trade name “Septon” (manufactured by Kuraray Co., Ltd.), The product name “Clayton” (manufactured by Kraton Polymer Japan), the product name “JSRTR” (manufactured by JSR), and the like can be mentioned.

  Among these thermoplastic resins, ethylene-propylene copolymer rubber or its acid-modified product, ethylene-octene copolymer rubber or its acid-modified product, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer Polymer, ethylene-n-butyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene-nonconjugated polyene copolymer rubber or acid-modified product thereof, ethylene-ethyl acrylate-maleic anhydride copolymer Polymers, olefinic thermoplastic elastomers, and styrene thermoplastic elastomers are preferred.

  The vinyl monomer forming the vinyl polymer segment which is a branch component of the graft copolymer 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 vinyl monomer having 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.

  More specifically, this vinyl monomer includes methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( Lauryl (meth) acrylate, stearyl (meth) acrylate, (meth) acrylic acid, maleic acid, maleic anhydride, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) acrylic Examples include glycidyl acid, (meth) acrylonitrile, and styrene. Among these, because of high affinity with polylactic acid resin, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate , 2-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, acrylonitrile and styrene are preferred.

  The mass average molecular weight of the vinyl polymer forming the vinyl polymer segment (measured by gel permeation chromatograph (GPC) in terms of styrene in tetrahydrofuran (THF)) is usually 1,000 to 2,000,000. , Preferably in the range of 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 graft copolymer is preferably 0.01 g / 10 min or more, more preferably 0.1 g / 10 min or more, and further preferably 1.0 g / 10. Min. Or more, 500 g / 10 min or less, preferably 300 g / 10 min or less, more preferably 200 g / 10 min or less. This MFR is measured under the conditions of a resin temperature of 230 ° C. and a measurement load of 21.18 N in accordance with the method defined in JIS K7210. When the MFR is in the range of 0.01 g / 10 min to 500 g / 10 min, good affinity between the graft copolymer and the polylactic acid resin can be obtained.

  In the graft copolymer, the thermoplastic resin segment is usually 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, 99% by mass or less, preferably 95% by mass or less, more preferably. The vinyl polymer segment is usually 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and 95% by mass or less, preferably 90% by mass or less. Preferably it is 80 mass% or less. If the thermoplastic resin segment is 5% by mass or more, or the vinyl polymer segment is 95% by mass or less, the dispersibility of the graft copolymer to the polylactic acid resin is not lowered, and the molding has a good appearance. The body is obtained. On the other hand, if the thermoplastic resin segment is 99% by mass or less or the vinyl polymer segment is 1% by mass or more, a sufficient improvement effect on the polylactic acid resin can be obtained. Based on this knowledge, the interaction between the polylactic acid resin and the graft copolymer is adjusted by changing the polarity of the graft copolymer by adjusting the ratio of the thermoplastic resin segment and the vinyl polymer segment. can do.

  The grafting method for producing the graft copolymer may be any generally known method such as chain transfer method or ionizing radiation irradiation method, but the method shown below is most preferable. This is because the production method is simple, the grafting efficiency is high, the secondary agglomeration of the vinyl polymer segment due to heat does not occur, the graft copolymer can be easily mixed with the polylactic acid resin, and the interaction between the two is excellent. This is because.

  As a commercial item of said graft copolymer, brand name "Modiper" (made by NOF Corporation), "RESEDA" (made by Toa Gosei Co., Ltd.), etc. are mentioned, for example.

  When two or more resins are used as the compatibilizer, the blending ratio can be adjusted in consideration of the compatibility between the polylactic acid resin and the polyolefin resin, the transparency of the mixed resin, the viscoelasticity value, and the like. For example, hydrogenated products of the above graft copolymers, copolymers of modified styrene-aromatic hydrocarbons and conjugated diene hydrocarbons, copolymers of aromatic vinyl hydrocarbons and conjugated diene hydrocarbons Alternatively, a copolymer having a polar group introduced therein can be used as the mixed resin. When two or more compatibilizers are used, it is preferable because the compatibility effect between the polylactic acid resin and the polyolefin resin is further promoted and the transparency of the film is improved.

(Mass ratio of polylactic acid resin, polyolefin resin and compatibilizer)
1st invention WHEREIN: The polylactic acid-type resin which comprises the said B layer, the mass ratio of the polyolefin resin, and the compatibilizing agent is a polylactic acid-type resin with respect to 100 mass% of resin compositions which comprise the said B layer. Is 60 mass% or more and 89 mass% or less, polyolefin resin is 10 mass% or more and 40 mass% or less, and a compatibilizing agent is preferably 1 mass% or more and 15 mass% or less.

  More preferably, the polylactic acid resin is 70% by mass or more and 87% by mass or less, the polyolefin resin is 10% by mass or more and 30% by mass or less, and the compatibilizer is 3% by mass or more and 12% by mass or less. The polylactic acid resin is 75% by mass or more and 85% by mass or less, the polyolefin resin is 10% by mass or more and 25% by mass or less, and the compatibilizing agent is 5% by mass or more and 10% by mass or less. If the mass ratio of the polyolefin-based resin is 10% by mass or more, the rupture resistance of the film is not significantly reduced, and if it is 40% by mass or less, the delamination strength with the A layer adjacent to the B layer Can be maintained within a predetermined range. Further, if the mass ratio of the compatibilizer is 3% by mass or more, the compatibility effect is exhibited and appearance defects are hardly generated, and if it is 12% by mass or less, the rigidity of the film is inhibited. Not preferred.

<Additives to layer A and layer B>
Further, in the first invention, the A layer and the B layer are other than the polyolefin resin, as long as the effects of the present invention are not significantly impaired, (meth) acrylic resin, polyethylene resin, polypropylene resin, polystyrene resin. (GPPS (general purpose polystyrene)), HIPS (high impact polystyrene), SBS (styrene-butadiene copolymer), SIS (styrene-isoprene copolymer), SEBS (styrene-ethylene-butylene-styrene copolymer), SEPS (Styrene-ethylene-propylene-styrene copolymer), styrene-carboxylic acid copolymer) and the like, and may further contain at least one thermoplastic resin such as a polyamide-based resin and a polyoxymethylene-based resin.

  In particular, since (meth) acrylic resins are compatible with polylactic acid resins, blending with polylactic acid resins enables adjustment of the glass transition temperature that affects shrinkage characteristics, and results in shrink finish. It becomes a resin effective for improvement.

  Among the (meth) acrylic resins, methacrylic resins are preferable. This methacrylic resin refers to a copolymer of methyl methacrylate homopolymer or 50% by mass or more of methyl methacrylate and another vinyl monomer. Examples of the vinyl monomer include methacrylic acid esters, acrylic acid esters, unsaturated acids, styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, and the like.

  Specific examples of the methacrylic acid esters include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, and the like.

  Specific examples of the acrylate esters include methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, and the like. Is mentioned. Furthermore, examples of the unsaturated acids include methacrylic acid and acrylic acid.

  The copolymer constituting the methacrylic resin further includes elastomer components such as polybutadiene, butadiene-butyl acrylate copolymer, polybutyl acrylate copolymer, glutaric anhydride units, and glutarimide units. May be included.

  Among these, from the viewpoint of rigidity and moldability, polymethyl methacrylate (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 the first invention, polymethyl methacrylate (PMMA) is most preferably used. By blending the present resin, it is possible to increase the glass transition temperature of the methacrylic resin, and as a result, the rapid onset of shrinkage at the time of shrinkage can be relieved, and good shrinkage finish can be obtained.

  The content of the (meth) acrylic resin is 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, based on the total resin composition of the A layer or B layer (100% by mass). And 30% by mass or less, preferably 25% by mass or less, more preferably 20% by mass or less.

  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.), “Artugrass” (Atofina) -Made by Japan), "Delpet" (made by Asahi Kasei Chemicals), etc. are mentioned.

  Furthermore, in the first invention, a soft resin is used in the above mixed resin for the purpose of improving various properties of impact resistance, transparency, moldability and heat-shrinkable film within a range that does not significantly impair the effects of the present invention. May be added.

  Examples of the soft resin include aliphatic polyester resins excluding polylactic acid resins, aromatic aliphatic polyester resins, and copolymers of diol, dicarboxylic acid, and lactic acid resin.

  Among the above-mentioned soft resins, aliphatic polyester resins excluding polylactic acid resins are preferable. The aliphatic polyester resin excluding the polylactic acid resin is an aliphatic polyester mainly composed of an aliphatic dicarboxylic acid or a derivative thereof and an aliphatic polyhydric alcohol. Examples of the aliphatic dicarboxylic acid residue constituting the aliphatic polyester resin include residues derived from succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like. Examples of the aliphatic polyhydric alcohol residue include aliphatic diol residues derived from ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like.

  The aliphatic dicarboxylic acid residue suitably used in the first invention is a succinic acid residue or an adipic acid residue, and the aliphatic polyhydric alcohol residue is a 1,4-butanediol residue.

  Furthermore, the aliphatic dicarboxylic acid suitably used in the first invention preferably has a melting point of 100 ° C. or higher and 170 ° C. or lower. By adjusting the melting point to the range, the aliphatic polyester can maintain a crystalline state even in the range of 60 ° C. to 100 ° C. in which the normal shrinkage is performed. As a result, it plays a role like a column at the time of shrinkage. As a result, it is possible to obtain even better shrinkage finish.

  The content of the aliphatic polyester resin excluding the polylactic acid is 5% by mass or more, preferably 10% by mass or more, more preferably 15%, based on the total resin composition of the A layer or B layer (100% by mass). It is 30% by mass or less, preferably 25% by mass or less, more preferably 20% by mass or less.

  In the first invention, for the purpose of improving various properties of impact resistance, transparency, moldability and heat shrinkable film, a plasticizer may be further added within a range that does not significantly impair the effects of the present invention. . Examples of the plasticizer include fatty acid ester plasticizers, phthalate ester plasticizers, trimellitic ester plasticizers, and the like.

  Specific examples of the fatty acid ester plasticizer include dibutyl adipate, diisobutyl adipate, diisononyl adipate, diisodecyl adipate, di (2-ethylhexyl) adipate, di (n-octyl) adipate, di (n-decyl) adipate, dibutyldipropyl Examples include glycol adipate, dibutyl sebacate, di (2-ethylhexyl) sebacate, di (n-hexyl) azelate, di (2-ethylhexyl) azelate, di (2-ethylhexyl) dodecanedionate and the like.

  Specific examples of the phthalate ester plasticizer include diisononyl phthalate, diisodecyl phthalate, and di (2-ethylhexyl) phthalate. Further, specific examples of the trimellitic acid ester plasticizer include tri (2-ethylhexyl) trimellitate.

<The manufacturing method of 1st invention>
1st invention can be manufactured by a well-known method using the said mixed resin. 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. In the case of printing, annealing, cooling, and printing, a corona discharge treatment is performed on the surface, and the film is obtained by winding with a winder. Moreover, the method of cutting open the film manufactured by the tubular method and making it planar is also mentioned.

  The stretching ratio in the stretching is such that the longitudinal direction is 2 to 10 times, the transverse direction is 2 to 10 times, and preferably 3 to 6 times in the longitudinal direction, for applications such as overlapping and shrinking in two directions. Hereinafter, the horizontal direction is about 3 to 6 times. On the other hand, in applications such as heat-shrinkable labels that shrink mainly in one direction, the direction corresponding to the main shrinkage direction is 2 to 10 times, preferably 3 to 7 times, more preferably 3 to 5 times. The direction perpendicular thereto is 1 or more and 2 or less (1 time indicates that the film is not stretched), preferably 1.01 or more and 1.5 or less, and substantially uniaxially stretched. It is desirable to select a magnification ratio in the category of. 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 to be used and the properties required for the heat-shrinkable film, but is generally 60 ° C. or higher, preferably 70 ° C. or higher, and the upper limit is 100 ° C. or lower, preferably 90 ° C. It is controlled within the following range.

  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.

  In addition, the first invention can perform surface treatment and surface processing such as corona treatment, printing, coating, and vapor deposition as needed, and bag making processing and perforation processing using various solvents and heat sealing. .

<Layer structure of film>
1st invention is a laminated | multilayer film comprised from the at least 2 layer by which A layer and B layer were laminated | stacked in this order, Comprising: It has A layer as an outermost layer. The film of the present invention preferably has a B layer as an inner layer. Since the film of the present invention only needs to have at least an A layer and a B layer, for example, it may have a two-layer structure in which an A layer and a B layer are laminated, or as in A layer / B layer / A layer. , A layer may be a three-layer structure that is present in the outermost layers on both sides, and the three-layer structure is preferred. Moreover, the film provided with the layer structure which laminated | stacked the other layer (C layer) may be sufficient. Specifically, layer configurations such as A layer / B layer, A layer / B layer / A layer, A layer / B layer / C layer / A layer, A layer / B layer / C layer / B layer / A layer, etc. Is a laminated film. In this case, the lamination ratio of each layer can be appropriately adjusted according to the application and purpose.

  Examples of the method for forming the laminate include a co-extrusion method, a method of forming a film of each layer, and then superposing and heat-sealing, a method of bonding with an adhesive, and the like.

  Next, a film having a three-layer structure of (A) layer / (B) layer / (A) layer, which is one of the preferred embodiments of the first 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 front and back layers (A) 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 60% or less, Preferably it is 50% or less. The thickness ratio of the intermediate layer (B) layer to the total film thickness 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, more preferably. Is 80% or less. If the thickness ratio of the front and back layers to the thickness of the entire film is within the above range, the surface roughness of the intermediate layer (B) layer mainly composed of a resin composition comprising a polylactic acid resin, a polyolefin resin, and a compatibilizing agent And a film having excellent transparency and gloss can be obtained. Moreover, if the thickness ratio of the intermediate layer to the thickness of the entire film is within the above range, a film having excellent rupture resistance can be obtained, and heat shrinkage suitable for applications such as shrink wrapping, shrink tying wrapping, and shrink labels. Can be obtained with good balance.

  The total thickness of the first invention is not particularly limited, but it is preferably thinner from the viewpoint of transparency, shrinkage workability, raw material cost, and the like. Specifically, the total thickness of the stretched film is preferably 80 μm or less, preferably 70 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.

<Physical and mechanical properties>
(Shrinkage factor)
In the first invention, it is important that the thermal shrinkage rate in the main shrinkage direction when immersed in warm water at 80 ° C. for 10 seconds is 20% or more, and more preferably 30% or more.

  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. At present, the shrinkage processing machine most commonly used industrially for labeling of PET bottles is generally called a steam shrinker that uses steam as a heating medium for shrinking. Furthermore, the heat-shrinkable film needs to be sufficiently heat-shrinked at a temperature as low as possible from the viewpoint of the influence of heat on the object to be coated. However, in the case of a film with high temperature dependence and extremely different shrinkage ratios depending on the temperature, parts with different shrinkage behavior tend to occur with respect to the temperature spots in the steam shrinker, so shrinkage spots, wrinkles, avatars, etc. occur. However, the shrink-finished appearance tends to deteriorate. From the viewpoint of including these industrial productivity, if the thermal shrinkage rate in the main shrinkage direction of the film when immersed in warm water at 80 ° C. for 10 seconds is 20% or more, the film is sufficiently adhered to the coated object within the shrinkage processing time. It is preferable because it can produce a good shrink-finished appearance without spots, wrinkles and avatars. From this, the film of the present invention preferably has a heat shrinkage at 80 ° C. of 20% or more and 70% or less.

  The “main shrinkage direction” means the larger one of the longitudinal direction and the transverse direction in the stretching direction. For example, when attached to a bottle, it is a direction corresponding to the outer circumferential direction.

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

  In addition, although the upper limit of said heat shrinkage is not described, since heat shrinkage does not become shorter than the length of the film before extending | stretching, the upper limit of heat shrinkage is a shrinkage rate used as the film length before extending | stretching. .

(transparency)
The transparency of the first invention is that when a film having a thickness of 50 μm conforms to JIS K7105, the total haze value is preferably 30% or less, more preferably 20% or less, and 15% or less. Is more preferably 10% or less, and most preferably 7% or less. The internal haze value is preferably 15% or less, more preferably 12% or less, further preferably 10% or less, and most preferably 6% or less. If the total haze value is 30% or less, the visibility of the covering on which the film is mounted can be maintained. If the internal haze value is 15% or less, the film surface is roughened by laminating the films. By suppressing, the total haze value of the film can be further reduced, and the transparency can be further improved.

(Tensile elongation at break)
The impact resistance of the first invention can be evaluated by the tensile elongation at break. In the tensile test at an atmospheric temperature of 0 ° C., the tensile elongation at break is 100% or more, preferably 150% or more, more preferably 200% or more in the film take-off (flow) direction (MD), particularly for label applications. is there. A tensile elongation at break of 100% or more at an atmospheric temperature of 0 ° C. is preferable because it is difficult to cause problems such as film breakage during printing and bag making processes. Further, even when the tension applied to the film increases as the speed of processes such as printing and bag making increases, it is preferable that the tensile breaking elongation is 150% or more, which makes it difficult to break. The upper limit is not particularly limited, but when considering the speed of the current process, it is considered that about 500% is sufficient, and when trying to give too much elongation, the rigidity of the film tends to decrease. .

  Further, in the tensile test in the 23 ° C. environment of the first invention, the elongation is 100% or more, preferably 200% or more, more preferably 300% or more in the film take-off (flow) direction (MD), particularly for label applications. is there. If the tensile elongation at break in an environment of 23 ° C. is 100% or more, such a problem that the film is hardly broken at the time of printing and bag making is preferable. In addition, even when the tension applied to the film increases as the speed of the printing / bag making process increases, it is difficult to break if the tensile elongation at break is 100% or more.

(Storage modulus E ')
In the first aspect of the present invention, the measurement temperature is in the range of −150 ° C. to 150 ° C. under the conditions of vibration frequency 10 Hz, strain 0.1%, heating rate 2 ° C./min, and chuck 2.5 cm. The storage elastic modulus (E ′) at 20 ° C. when dynamic viscoelasticity is measured in the direction orthogonal to the direction is preferably in the range of 1,000 MPa to 3,000 MPa, and is preferably 1,200 MPa to 2,500 MPa. More preferably, it is the range. If the storage elastic modulus E ′ of the film is 1,000 MPa or more, the waist as a whole film (rigidity at room temperature) can be increased, the film becomes too soft and easily deformed, printing, bag making, etc. When the film is stretched by roll tension during secondary processing, or when the film thickness is reduced, when the film made in a container such as a PET bottle is covered with a labeling machine, This is preferable because it is difficult for problems such as the yield to be easily lowered due to bending of the hips. On the other hand, if the storage elastic modulus E ′ of the film is within 3,000 MPa, the film is hard and hardly stretched, and wrinkles are easily formed during the secondary processing. ,preferable.

  In order to set the storage elastic modulus (E ′) at 20 ° C. in the direction orthogonal to the film stretching direction to be in the range of 1,000 MPa to 3,000 MPa, the resin composition of each layer should be in the range specified in the present invention. Importantly, in the case of a single layer, adjustment is possible by adjusting the rigidity and fat composition of the mixed resin. Moreover, in the case of a laminated film, it can be adjusted by changing the thickness ratio of the outer layer and the inner layer to the thickness of the entire film. For example, when it is desired to increase the storage elastic modulus (E ′), it can be adjusted by increasing the ratio of the PLA layer to the thickness of the entire laminated film and increasing the rigidity of the mixed resin layer.

(Natural shrinkage)
The natural shrinkage ratio of the first invention is desirably as small as possible. Generally, the natural shrinkage ratio of the heat-shrinkable film is, for example, preferably 3 after 30 days storage at 30 ° C. and 50% RH. Less than 0.0%, more preferably 2.0% or less, still more preferably 1.5% or less. If the natural shrinkage rate under the above conditions is less than 3.0%, even if the produced film is stored for a long period of time, it can be stably attached to a container or the like, and problems are hardly caused in practice. As a means for adjusting the natural shrinkage rate of the film, it is important that the resin composition of each layer is within the range specified in the present invention, and particularly the thickness ratio of the mixed resin layer to the entire film thickness is 10% or more. It is preferable to do.

[Second Invention (Molded Product), Third Invention (Heat Shrinkable Label), Fourth Invention (Container)]
The first invention can be processed from a planar shape to a cylindrical shape or the like by a packaged object and used 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.

  In addition, the first invention is excellent in the heat shrink property, shrink finish, transparency, etc. of the film, so its use is not particularly limited. By laminating and forming functional layers, 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 first 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 constricted center, Even a square column, pentagonal column, hexagonal column or the like having a square shape 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.

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

  As the material constituting the plastic package, in addition to the above resins, polystyrene, rubber-modified impact-resistant polystyrene (HIPS), styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer Polymer, acrylonitrile-butadiene-styrene copolymer (ABS), (meth) acrylic acid-butadiene-styrene copolymer (MBS), polyvinyl chloride resin, phenol resin, urea resin, melamine resin, epoxy resin, A saturated polyester resin, a silicone resin, etc. can be mentioned. These plastic packages may be a mixture of two or more resins or a laminate.

  Hereinafter, the first invention (film), the third invention (heat-shrinkable label), and the fourth invention (a container equipped with the label) will be described with reference to examples.

  In addition, the measured value and evaluation which are shown to an Example were performed as follows. In the examples, the take-up (flow) direction of the laminated film is described as the “longitudinal” direction (or “MD”), and the perpendicular direction thereof is described as the “transverse” direction (or “TD”).

(1) Heat Shrinkage The obtained heat shrinkable film was cut into a size of 100 mm in length and 100 mm in width, and immersed in a hot water bath at 70 ° C. and 80 ° C. for 10 seconds, and the amount of shrinkage was measured. For the thermal shrinkage, the ratio of shrinkage to the original size before shrinkage was expressed in% in the vertical and horizontal directions.
◎: When the thermal shrinkage rate is 40% or more ○: When the thermal shrinkage rate is 20% or more and less than 40% ×: When the thermal shrinkage rate is less than 20%

(2) Tensile elongation at break The obtained heat-shrinkable film was cut into a size of 110 mm in the direction (longitudinal direction) perpendicular to the main shrinkage direction and 15 mm in the main shrinkage direction, and in accordance with JIS K6732, a tensile speed of 100 mm / The tensile elongation at break in the direction (longitudinal direction) perpendicular to the main shrinkage direction of the film at an atmospheric temperature of 0 ° C. and 23 ° C. was measured in min, the average value of 10 measurements was measured, and evaluated according to the following criteria did. The measured values and evaluation results are shown in Table 1.
◎: When the tensile elongation at break exceeds 200% ○: When the tensile elongation at break exceeds 100% and is 200% or less ×: When the tensile elongation at break is 100% or less

(3) Haze value In order to evaluate the transparency of the obtained film, the total haze value was measured according to JIS K7105.
◎: When all haze values are less than 7% ○: When all haze values are 7% or more and less than 9% ×: When all haze values are 9% or more

Moreover, the raw material used by each Example and the comparative example is as follows.
(Polylactic acid resin)
-Product made from Nature Works LLC, a brand name: NatureWorks4060D, L body / D body weight = 88/12, and it abbreviates as "PLA (1)" hereafter.
-Product made from Nature Works LLC, a brand name: NatureWorks4042D, L body / D body weight = 95/5, and it abbreviates as "PLA (2)" hereafter.
-Product made from Nature Works LLC, brand name: NatureWorks4032D, L body / D body weight = 98.8 / 1.2, and it abbreviates as "PLA (3)" hereafter.

(Polyolefin resin)
* Product name: Versify 2400, polypropylene-ethylene random copolymer [polypropylene / ethylene = 85/15, 10 Hz storage elastic modulus: 10 MPa (20 ° C.), 3 MPa (70 ° C.)], hereinafter “PO” (1) ".

(Compatibilizer)
-NOF Corporation, trade name: Modiper A5200 [(ethylene-ethyl acrylate) -methyl methacrylate graft copolymer (= 70/30), 10 Hz storage elastic modulus: 85 MPa (20 ° C.), 14 MPa (70 ° C.) ], Hereinafter abbreviated as “Compatibilizer (1)”.

(Core shell type rubber)
-Product name: Metablene S2001 (hereinafter abbreviated as "core shell type rubber (1)") manufactured by Mitsubishi Rayon Co., Ltd.
-Product name: Metabrene S2006 (hereinafter abbreviated as "core shell type rubber (2)") manufactured by Mitsubishi Rayon Co., Ltd.
-Mitsubishi Rayon Co., Ltd., trade name: Metabrene W450A (hereinafter abbreviated as "core shell type rubber (3)")
-Product name: Metabrene SX005 (hereinafter abbreviated as "core shell type rubber (4)") manufactured by Mitsubishi Rayon Co., Ltd.
-Kaneka Corporation, brand name: Kane Ace FM-21 (hereinafter abbreviated as “core shell type rubber (5)”)
-Product name: Kane Ace FM-40 (hereinafter abbreviated as “core shell type rubber (6)”) manufactured by Kaneka Corporation.
-Kaneka Corporation, brand name: Kane Ace FM-53 (hereinafter abbreviated as “core shell type rubber (7)”)
-Kaneka Co., Ltd., trade name: Kane Ace UF-100 (hereinafter abbreviated as “core shell type rubber (8)”)

(Examples and Comparative Examples)
As shown in Tables 1 to 3, PLA (1) 33 mass%, PLA (2) 44 mass%, PO (1) 17 mass%, and compatibilizer (1) 7 mass% are mixed and biaxial extrusion Machine (Mitsubishi Heavy Industries, Ltd.), melted and mixed at a set temperature of 210 ° C., extruded from a strand die at a set temperature of 210 ° C., then cooled in a water tank, cut with a strand cutter, and pellets Obtained (referred to as B layer resin (1)).
In addition, as shown in Table 2, except that PLA (1) 16% by mass, PLA (2) 27% by mass and PO (1) 50% by mass, and compatibilizer (1) 7% by mass were changed. Pellets were obtained by a method similar to that for the B layer resin (1) and used for the study shown in Comparative Example 5 described later (referred to as B layer resin (2)).
Moreover, as shown in Table 2, the same method as that for the B-layer resin (1) except that PLA (1) 33 mass%, PLA (2) 44 mass% and PO (1) 24 mass% were changed. Pellets were obtained by the above and used for the investigation shown in Comparative Example 6 described later (referred to as B layer resin (3)).
Next, as shown in Table 1, PLA (1) 40 mass%, PLA (2) 50 mass%, and core-shell type rubbers (1) to (8) were mixed with 10 mass%, respectively. (Mitsubishi Heavy Industries, Ltd.), melted and mixed at a set temperature of 210 ° C., extruded from a strand die with a set temperature of 210 ° C., and then cooled with a water tank and cut with a strand cutter to obtain pellets. (Respectively referred to as A layer resins (1) to (8)).
Moreover, as shown in Table 3, except for changing to PLA (1) 42.5 mass%, PLA (2) 52.5 mass%, and core-shell type rubber (2) 5 mass%, the resin for the A layer ( Pellets were obtained by the same method as in 1) to (8), and used for the investigation shown in Example 9 described later (referred to as A layer resin (9)).
Moreover, as shown in Table 3, except for changing PLA (1) 35% by mass, PLA (2) 45% by mass, and core-shell type rubber (2) 20% by mass, resins for A layer (1) to ( Pellets were obtained by the same method as in 8) and used for the study shown in Example 10 described later (referred to as A layer resin (10)).
Moreover, as shown in Table 3, except for changing PLA (1) 42.5 mass%, PLA (2) 52.5 mass%, and core-shell type rubber (3) 5 mass%, the resin for the A layer ( Pellets were obtained by the same method as in 1) to (8), and used for the study shown in Example 11 described later (referred to as A layer resin (11)).
In addition, as shown in Table 3, pellets were obtained in the same manner as the A-layer resins (1) to (8) except that PLA (1) was 45% by mass and PLA (2) was 55% by mass. This was used in the study shown in Comparative Example 7 described later (referred to as A layer resin (12)).
Moreover, as shown in Table 3, except for changing PLA (1) 25% by mass, PLA (2) 35% by mass, and core-shell type rubber (2) 40% by mass, resins for A layer (1) to ( Pellets were obtained by the same method as in 8) and used for the study shown in Comparative Example 8 described later (referred to as A layer resin (13)).

Example 1
Single-screw extrusion for forming B layer in equipment capable of co-extrusion of layer A / layer B / layer A by two single-screw extruders (Mitsubishi Heavy Industries, Ltd.) and two types of three-layer multi-manifold die The pelletized B layer resin (1) is introduced into the machine, and the A layer resin (1) is introduced into the single-screw extruder for forming the A layer, and melted at a preset temperature of 210 ° C. for each extruder. After mixing, the layers are coextruded so that the thickness of each layer is A layer / B layer / A layer = 30 μm / 190 μm / 30 μm, taken up with a cast roll at 50 ° C., cooled and solidified, and unstretched laminate having a width of 200 mm and a thickness of 250 μm A sheet was obtained. Next, this sheet was stretched 5 times in the transverse direction using a film tenter (manufactured by Kyoto Kikai Co., Ltd.) in a preheating 75 ° C., stretching 75 ° C., heat treatment 85 ° C., preheating 1 zone, stretching 3 zone, and heat treatment 2 zone. Thus, a heat-shrinkable film having a thickness of 50 μm was obtained. The evaluation results of the obtained film are shown in Table 1.

(Examples 2 to 8)
As shown in Table 1, heat shrinkability was achieved by the same method as in Example 1 except that the A layer resin (1) in Example 1 was changed to A layer resins (2) to (8), respectively. A film was obtained. The evaluation results of the obtained film are shown in Table 1.

(Comparative Example 1)
Single-screw extrusion for forming B layer in equipment capable of co-extrusion of layer A / layer B / layer A by two single-screw extruders (Mitsubishi Heavy Industries, Ltd.) and two types of three-layer multi-manifold die Introducing the pelletized B layer resin (1) into the machine, and using a single screw extruder for forming the A layer, melt-mixing at an extruder set temperature of 210 ° C. The sheet was extruded to 250 μm, taken up with a cast roll at 50 ° C., and cooled and solidified to obtain an unstretched laminated sheet having a width of 200 mm and a thickness of 250 μm. Next, this sheet was stretched 5 times in the transverse direction using a film tenter (manufactured by Kyoto Kikai Co., Ltd.) in a preheating 75 ° C., stretching 75 ° C., heat treatment 85 ° C., preheating 1 zone, stretching 3 zone, and heat treatment 2 zone. Thus, a heat-shrinkable film having a thickness of 50 μm was obtained. The evaluation results of the obtained film are shown in Table 1.

(Comparative Example 2)
Single-screw extrusion for forming B layer in equipment capable of co-extrusion of layer A / layer B / layer A by two single-screw extruders (Mitsubishi Heavy Industries, Ltd.) and two types of three-layer multi-manifold die Without using a machine, introduce the A layer resin (1) into a single-screw extruder that forms the A layer, melt and mix at an extruder set temperature of 210 ° C., and then extrude the A layer to a thickness of 250 μm. Then, it was taken up by a cast roll at 50 ° C. and cooled and solidified to obtain an unstretched laminated sheet having a width of 200 mm and a thickness of 250 μm. Next, this sheet was stretched 5 times in the transverse direction using a film tenter (manufactured by Kyoto Kikai Co., Ltd.) in a preheating 75 ° C., stretching 75 ° C., heat treatment 85 ° C., preheating 1 zone, stretching 3 zone, and heat treatment 2 zone. Thus, a heat-shrinkable film having a thickness of 50 μm was obtained. The evaluation results of the obtained film are shown in Table 1.

(Comparative Examples 3 and 4)
A heat-shrinkable film was obtained in the same manner as in Comparative Example 2, except that the A-layer resins (2) and (3) were introduced into the single-screw extruder for forming the A layer. The evaluation results of the obtained film are shown in Table 1.

  About the film obtained in Examples 1-8, the external appearance of the film was also favorable and the transparency seen from all the haze was also favorable. Also, the tensile elongation at break of MD of the film showed good values at both 23 ° C. and 0 ° C. On the other hand, regarding the B layer single layer film obtained in Comparative Example 1, although the tensile elongation at break is good, the total haze due to surface roughness is remarkably increased, and it is difficult to maintain the transparency of the film. Moreover, regarding the films obtained in Comparative Examples 2 to 4, although the transparency of the films is good, the tensile elongation at break is low, and the rupture resistance required in the printing process and the bag making process, which are shrink film processing steps. Not enough to get.

(Comparative Example 5)
Single-screw extrusion for forming B layer in equipment capable of co-extrusion of layer A / layer B / layer A by two single-screw extruders (Mitsubishi Heavy Industries, Ltd.) and two types of three-layer multi-manifold die The pelletized B layer resin (2) is introduced into the machine, the A layer resin (2) is introduced into the single-screw extruder that forms the A layer, and melted at the extruder set temperature of 210 ° C. After mixing, the layers are coextruded so that the thickness of each layer is A layer / B layer / A layer = 30 μm / 190 μm / 30 μm, taken up with a cast roll at 50 ° C., cooled and solidified, and unstretched laminate having a width of 200 mm and a thickness of 250 μm A sheet was obtained. Next, this sheet was stretched 5 times in the transverse direction using a film tenter (manufactured by Kyoto Kikai Co., Ltd.) in a preheating 75 ° C., stretching 75 ° C., heat treatment 85 ° C., preheating 1 zone, stretching 3 zone, and heat treatment 2 zone. Thus, a heat-shrinkable film having a thickness of 50 μm was obtained. The evaluation results of the obtained film are shown in Table 2.

(Comparative Example 6)
As shown in Table 2, a heat-shrinkable film was obtained by the same method as in Comparative Example 5 except that the pelletized B layer resin (3) was introduced into a single screw extruder for forming the B layer. It was. The evaluation results of the obtained film are shown in Table 2.

  As described above, the film obtained in Example 2 has excellent transparency and fracture resistance, whereas the film obtained in Comparative Example 5 or Comparative Example 6 is a film. Spotted unevenness occurred, and the appearance was poor. Moreover, when the adhesive tape was affixed on the film obtained in Example 2 and Comparative Examples 5 and 6 and the tape was peeled off, delamination occurred in the film obtained in Comparative Example 5.

(Examples 9 to 11, Comparative Examples 7 and 8)
As shown in Table 3, the heat-shrinkable film was formed by the same method as in Example 1 except that the A-layer resins (9) to (13) were introduced into the single-screw extruder for forming the A layer. Obtained. The evaluation results of the obtained film are shown in Table 3.

  As shown in Table 3, with respect to the films obtained in Examples 2, 4, and 9 to 11, while having good transparency and rupture resistance, a comparative example in which no core-shell rubber was added In No. 7, the transparency was good, but the tensile strength and elongation at 0 ° C. were insufficient. When the tensile strength and elongation at low temperatures are insufficient, it is difficult to respond to the case where the line speed is increased in the printing process or the like, and it is difficult to say that the required characteristics as a shrink film are satisfied. . Moreover, like the film obtained in Comparative Example 8, when the addition amount of the core-shell type rubber is added within the range deviating from the scope of the present invention, the adhesive tape is attached to the film while not only reducing the transparency. When the tape was peeled off, delamination occurred.

  The heat-shrinkable film (Examples 1 to 8) defined in the present invention includes a heat-shrinkable single layer film (Comparative Example 1) composed of a polylactic acid-based resin, a polyolefin-based resin, and a compatibilizer, and polylactic acid. Heat-shrinkable single layer film (Comparative Examples 2 to 4) composed of a resin and a core-shell type rubber, or an intermediate layer and a polylactic acid resin composed of a polylactic acid resin and a polyolefin resin, and a compatibilizer Compared with a heat-shrinkable film (Comparative Example 7) having a front and back layer composed only of the film, it is a good film that satisfies both the transparency and rupture resistance of the film and satisfies the required characteristics as a shrink film. Indicated. Moreover, the heat-shrinkable film (Examples 1-11) prescribed | regulated to this invention was excellent in the low-temperature shrinkage | contraction characteristic, impact resistance, transparency, external appearance, and handling property. On the other hand, the film (Comparative Example 5) in which the mass ratio of the polylactic acid-based resin to the polyolefin-based resin exceeds the range defined by the present invention is considered to result from poor dispersion of the polylactic acid-based resin and the polyolefin-based resin. The appearance was bad. Further, since the mass ratio of the polyolefin-based resin exceeds the range defined by the present invention, delamination with the adjacent outermost layer easily occurred. Further, regarding the film (Comparative Example 6) in which the mass ratio of the compatibilizing agent is outside the range specified by the present invention, a poor appearance occurs, and furthermore, the tensile elongation at break at a low temperature is remarkably reduced. It was. Furthermore, delamination with the adjacent outermost layer easily occurred even with respect to a film (Comparative Example 8) in which the amount of core-shell rubber added was outside the range defined by the present invention.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, it can be changed as appropriate without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and a heat-shrinkable film accompanied by such a change, a molded article using the film, and heat-shrinkable It should be understood that a label and a container formed by mounting the molded article and the label are also included in the technical scope of the present invention.

  The heat-shrinkable film of the present invention can be suitably used for applications such as shrink packaging, shrink-bound packaging, and shrink labels.

Claims (7)

A layer composed of a resin composition containing a polylactic acid resin as a main component and containing a core-shell type rubber (provided that the A layer is the outermost layer), a polylactic acid resin, a polyolefin resin, and a compatibilizer. A layered film composed of at least two layers in which a B layer mainly composed of a resin composition is laminated in this order,
The compatibilizer is ethylene-α olefin copolymer rubber, ethylene-α olefin-nonconjugated polyene copolymer rubber, ethylene- (meth) acrylic acid alkyl ester copolymer, ethylene-vinyl acetate copolymer, olefin. A graft comprising a thermoplastic resin segment selected from the group consisting of a thermoplastic thermoplastic elastomer and a styrene thermoplastic elastomer as a trunk component and a vinyl polymer segment formed from at least one vinyl monomer as a branch component A copolymer,
A heat-shrinkable laminated film, wherein the laminated film is stretched in at least one direction and has a heat shrinkage rate of 20% or more in the main shrinkage direction when immersed in warm water at 80 ° C. for 10 seconds. The heat shrinkage according to claim 1, wherein the shell in the core-shell type rubber contained in the resin composition constituting the A layer is (meth) acrylic acid ester, and the core in the core-shell type rubber is silicone rubber or acrylic rubber. Laminated film. The heat-shrinkable laminated film according to claim 1 or 2, wherein the content of the core-shell rubber is 3% by mass or more and 20% by mass or less with respect to 100% by mass of the resin composition constituting the A layer. The polylactic acid resin contained in the B layer is 60% by mass or more and 89% by mass or less, and the polyolefin resin is 10% by mass or more and 40% by mass with respect to 100% by mass of the entire resin composition constituting the B layer. The heat-shrinkable laminated film according to claim 1, wherein the compatibilizer is 1% by mass or more and 15% by mass or less. A molded article using the heat-shrinkable laminated film according to claim 1 as a base material. The heat-shrinkable label which used the heat-shrinkable laminated film in any one of Claims 1-4 as a base material. A container equipped with the molded article according to claim 5 or the heat-shrinkable label according to claim 6.