JP2017052209A - Polylactic acid laminated film, heat-shrinkable laminated film using the laminated film, molded article and heat-shrinkable label using the heat-shrinkable laminated film, and container using the molded article or having label mounted thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid laminated film which is excellent in mechanical characteristics such as breaking resistance and transparency, and is suitable for packaging application, shrinkable label, and the like.SOLUTION: The polylactic acid laminated film is provided that has an I layer composed of a resin composition comprising a polylactic acid resin (A) and a thermoplastic polyurethane elastomer (B), and a II layer composed of a resin composition comprising the polylactic acid resin (A), the polyolefin resin (C) and a compatibilizer (D), and that is constituted of at least three or more layers laminated in order of I/II/I, the thermoplastic polyurethane elastomer (B) satisfying at least one of (a): comprising polysiloxane and (b): comprising at least one of aliphatic isocyanate and alicyclic isocyanate.SELECTED DRAWING: None

Description

  The present invention relates to a polylactic acid-based laminated film excellent in transparency and fracture resistance. Further, the present invention relates to a heat-shrinkable laminated film using the laminated film, a molded product using the heat-shrinkable laminated film, a heat-shrinkable label, and a container using the molded product or attached with the label. .

  Polylactic acid-based resins are plant-derived materials that use lactic acid obtained by fermentation of starch as a raw material, and are attracting attention from the viewpoints of measures against global warming and substitution of petroleum resources that are expected to be depleted in the future. This polylactic acid-based resin has features such as excellent transparency and rigidity, but also has disadvantages such as being hard and brittle. Therefore, for such modification of the polylactic acid-based resin, various technical studies have been conventionally made in order to use the polylactic acid-based resin as an environmentally friendly packaging material.

  By the way, many beverages such as tea, juice, and coffee are currently sold in a state of being filled in containers such as plastic bottles, and in recent years, plastic bottle sales of alcoholic beverages such as wine have been seen. . As such diversity increases, the importance of heat-shrinkable labels that are mounted to differentiate from other products and to improve the visibility of products is increasing. The heat-shrinkable label is used not only for beverages but also for foods, toiletries, medical products, chemicals, and industrial products.

  This heat-shrinkable label printing is usually applied on the back side of the film to prevent the printed material from slipping off due to rubbing or scratching between containers, and therefore the heat-shrinkable label original film requires high transparency. Is done. Therefore, polyvinyl chloride resin, polystyrene resin, aromatic polyester resin, and polylactic acid resin are used as the material of the film. Among them, the polylactic acid resin is used for the reasons described above. It is also attracting attention as a material for heat-shrinkable films.

  However, in general, polylactic acid resin has low impact resistance, so it is required when passing through a printing process in which a film passes at high speed via many rolls such as gravure printing and a processing process such as a bag making process. There is a problem that the fracture resistance is insufficient.

  As a method for improving the brittleness of the polylactic acid resin, a method of adding an elastomer is known. For example, Patent Document 1 proposes a crystalline biodegradable resin composition of an aliphatic polyester and a modified elastomer. Patent Document 2 proposes a thermoplastic polymer composition comprising an aliphatic polyester, a thermoplastic elastomer, and an inorganic filler. Patent Document 3 proposes a melt-mixed resin composition of polylactic acid and polyurethane. Further, Patent Document 4 proposes a resin composition comprising an aliphatic polyester and a thermoplastic polyurethane elastomer.

JP 2004-035691 A JP 2008-063577 A JP 2002-037995 A JP 2008-266454 A

However, since the technique of Patent Document 1 aims to improve heat resistance in addition to mechanical characteristics, it requires an annealing treatment at a glass transition point Tg or higher. With such a composition, it is difficult to ensure the high transparency and shrinkage rate necessary for heat shrink labels. Moreover, the technique of patent document 2 has no mention regarding the transparency which should be considered when polylactic acid and a thermoplastic elastomer are blended. Patent Documents 3 and 4 disclose techniques for blending polyurethane with polylactic acid or aliphatic polyester, but these are also mainly aimed at improving the brittleness of the polylactic acid resin, and the transparency is No consideration is given and no mention is made of the composition of the elastomer necessary to achieve transparency.
Thus, in the prior art, it was difficult to obtain a film having excellent transparency and mechanical properties such as fracture resistance.

  The present invention has been made in view of the above problems, that is, the object of the present invention is to satisfy the fracture resistance and to have excellent transparency and suitable for uses such as packaging and shrinkage labels. Is to provide.

  Another subject of the present invention is a molded article using the above-mentioned polylactic acid-based laminated film and heat shrinkage, which is excellent in transparency and breakage resistance, and suitable for applications such as shrink wrapping, shrink tying wrapping and shrinkage labels. It is an object of the present invention to provide an adhesive label and a container equipped with the molded article or the heat-shrinkable label.

As a result of intensive studies to solve such problems of the prior art, the present inventors have completed the following invention.
That is, the present invention provides an I layer comprising a resin composition comprising a polylactic acid resin (A) and a thermoplastic polyurethane elastomer (B), a polylactic acid resin (A), a polyolefin resin (C), and a phase. A layer II composed of a resin composition containing a solubilizer (D) is a laminated film composed of at least three layers laminated in the order of I / II / I, wherein the thermoplastic polyurethane elastomer (B) is This is achieved by a polylactic acid-based laminated film characterized by satisfying at least one of the following (a) and (b).
(A) containing polysiloxane (b) containing at least one of aliphatic isocyanate and alicyclic isocyanate

  In the polylactic acid-based laminated film of the present invention, the content of the thermoplastic polyurethane-based elastomer (B) in the resin composition constituting the I layer is 3% by mass or more when the entire resin composition is 100% by mass. It is preferable that it is 65 mass% or less.

  In the resin composition constituting the II layer, the polylactic acid-based laminated film of the present invention has a polylactic acid-based resin (A) of 50% by mass or more and 96% by mass or less when the total resin composition is 100% by mass. It is preferable to contain 3 mass% or more and 35 mass% or less of polyolefin-type resin (C), and 1 to 15 mass% or less of compatibilizers (D).

  In the polylactic acid-based laminated film of the present invention, the compatibilizer (D) is a graft copolymer having a thermoplastic resin segment and a segment formed from at least one vinyl monomer. Is preferred.

  Another object of the present invention is to provide a heat-shrinkable laminated film using the polylactic acid-based laminated film of the present invention, a molded product using the heat-shrinkable laminated film, a heat-shrinkable label, and the molded product or This is achieved by a container equipped with a heat-shrinkable label.

  ADVANTAGE OF THE INVENTION According to this invention, the polylactic acid-type laminated | multilayer film which is excellent in transparency, an external appearance, and fracture resistance can be provided.

  Furthermore, according to the present invention, a heat-shrinkable film, a molded product, and a heat-shrinkable label, which are excellent in transparency, rupture resistance, and shrinkage finish properties, are suitable for applications such as shrink-bound packaging and shrinkage labels. Can be provided. Furthermore, according to this invention, the container equipped with the said molded article or heat-shrink label which has a transparent and beautiful external appearance can be provided.

  Hereinafter, as an example of the embodiment of the present invention, a polylactic acid-based laminated film (hereinafter referred to as “the film of the present invention”), the heat-shrinkable film of the present invention, the molded product of the present invention, the label of the present invention, the present invention The container will be described. However, the scope of the present invention is not limited to the embodiments described below.

  In the present specification, “main component” is intended to allow other components to be included within a range that does not hinder the action and effect of the resin contained as the main component. Further, the term does not limit the specific content, but it is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and 100% by mass or less, based on the entire constituent components. It is a component that occupies the range.

<Film of the present invention>
The film of the present invention comprises an I layer comprising a resin composition comprising a polylactic acid resin (A) and a thermoplastic polyurethane elastomer (B), a polylactic acid resin (A), a polyolefin resin (C), and The II layer made of the resin composition containing the compatibilizer (D) is a polylactic acid-based laminated film composed of at least three layers laminated in the order of I / II / I.

<I layer>
The film of this invention has I layer which consists of a resin composition containing a polylactic acid-type resin (A) and a thermoplastic polyurethane-type elastomer (B).

<Polylactic acid resin (A)>
The polylactic acid resin (A) used in the I layer of the film of the present invention is a homopolymer of D-lactic acid or L-lactic acid, or a copolymer thereof. Specifically, the structural unit is D- There are poly (D-lactic acid) which is 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, Also included are mixed resins of a plurality of the above-mentioned copolymers having different copolymerization ratios of D-lactic acid and L-lactic acid.

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”), preferably “1/99” to "10/90" or "90/10" to "99/1", more preferably "1/99" to "9.5 / 90.5" or "90.5 / 9.5" to " 99/1 ”, more preferably“ 1/99 ”to“ 9/91 ”or“ 91/9 ”to“ 99/1 ”.
When the D / L ratio is higher than 99 or less than 1, high crystallinity is exhibited, the melting point is high, and the 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 as a film in which crystallization is suppressed by adjusting stretching conditions, crystallization proceeds before shrinkage due to heating during heat shrinkage, and as a result, there is a tendency to cause shrinkage unevenness and insufficient shrinkage. .
On the other hand, when the D / L ratio is less than 90 and higher than 10, the crystallinity is almost completely lost. As a result, when the labels collide with each other after heat shrinkage, they are fused by heat. Trouble may occur. Further, in the stretching process, the thickness tends not to be uniform in the width direction, the surface smoothness is hardly imparted, and the transparency tends to be hindered.
By adjusting the D / L ratio within the above range, it is possible to obtain a heat-shrinkable film that hardly causes such problems and has excellent shrinkage characteristics. In the film of the present invention, polylactic acid resins having different D / L ratios can be blended. It is preferable to blend polylactic acid resins having different D / L ratios because the D / L ratio of the polylactic acid resins can be adjusted relatively easily. In this case, what is necessary is just to make it the value which averaged D / L ratio of several lactic acid-type polymer in the said 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.

  The polylactic acid-based resin (A) is a non-aliphatic dicarboxylic acid other than lactic acid such as α-hydroxycarboxylic acid and terephthalic acid as a small amount of copolymerization component as long as the essential properties are not impaired. At least one selected from the group consisting of aliphatic dicarboxylic acids such as 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.

Specific examples of α-hydroxycarboxylic acids other than lactic acid include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy- Examples include bifunctional aliphatic hydroxycarboxylic acids such as 3-methylbutyric acid, 2-methyllactic acid, and 2-hydroxycaproic acid, and lactones such as caprolactone, butyrolactone, and valerolactone.
Specific examples of the dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like. Examples of the diol include ethylene glycol, 1,4-butanediol, 1, 4-cyclohexane dimethanol etc. are mentioned.

  Copolymerization ratio [lactic acid / (α-hydroxycarboxylic acid other than lactic acid, diol, or dicarboxylic acid)] of a copolymer of lactic acid and α-hydroxycarboxylic acid, diol, or dicarboxylic acid other than lactic acid is particularly limited. Although not, the mass ratio is preferably “100/0” to “50/50”, more preferably “100/0” to “60/40”, and even more preferably “100/0” to “70/30”. It is. 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 polylactic acid resin (A) has a weight average molecular weight of 20,000 or more, preferably 40,000 or more, more preferably 60,000 or more, and considering the upper limit value, preferably 400,000 or less, preferably 350,000 or less, more preferably 300,000 or less. When the weight 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 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. The weight average molecular weight can be measured by gel permeation chromatography (hereinafter referred to as “GPC”).

  As a polymerization method of the polylactic acid-based resin (A), 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.

  Typical examples of the polylactic acid resin (A) include “Ingeo biopolymer” (manufactured by NatureWorks LLC), “REVODE” (manufactured by Kaisho Biomaterials Co., Ltd.), and the like.

<Thermoplastic polyurethane elastomer (B)>
It is important that the thermoplastic polyurethane-based elastomer (B) used in the I layer of the film of the present invention satisfies at least one of the following (a) and (b).
(A) containing polysiloxane (b) containing at least one of aliphatic isocyanate and alicyclic isocyanate

  The thermoplastic polyurethane-based elastomer (B) is generally obtained by reacting a polyol, a polyisocyanate, and a copolymerizable component with a chain extender as necessary.

  Specific examples of the polyol component include polyester polyols, polyester ether polyols, polyether polyols, and polycarbonate polyols.

Polyester polyols include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid, aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid, hexahydrophthalic acid, hexahydro And alicyclic dicarboxylic acids such as terephthalic acid and hexahydroisophthalic acid. Examples thereof also include ester compounds of dicarboxylic acids or polyester polyols obtained by condensation reaction between acid anhydrides and diols, and polylactone diols obtained by ring-opening polymerization of lactone monomers such as ε-caprolactone. Examples of the diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl- 1,3-propanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,4-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,8 -Octanediol, 1,9-nonanediol, 2,2-dimethylolheptane and the like may be mentioned, and these may be used in combination of two or more.
In addition, as the polyester ether-based polyol, the aliphatic dicarboxylic acid, the aromatic dicarboxylic acid, the aliphatic dicarboxylic acid, and an ester compound thereof, or an acid anhydride, glycols such as diethylene glycol, propylene oxide adduct, etc. Or the condensation reaction material with these mixtures, etc. are mentioned.

  Examples of the polyether-based polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or a copolymerized polyether thereof obtained by polymerizing cyclic ethers such as ethylene oxide, propylene oxide, and tetrahydrofuran.

  Examples of the polycarbonate polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1, 3-propanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,4-pentanediol, neopentyl glycol, 1,3-octanediol, 1,9-nonane Examples thereof include polycarbonate polyols obtained by reacting one or more polyhydric alcohols such as diol, 2,2-dimethylol heptane and diethylene glycol with ethylene carbonate, diethyl carbonate and the like. Further, it may be a copolymer of polycaprolactone polyol and polyhexamethylene carbonate.

  Examples of the isocyanate component include 1,6-hexamethylene diisocyanate (HDI), 2,2,4-trimethylenehexamethylene diisocyanate, lysine methyl ester diisocyanate, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 1,5-octyl. Aliphatic isocyanates such as diisocyanates and dimer acid diisocyanates; 4,4'-dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), hydrogenated tolylene diisocyanate, methylcyclohexane diisocyanate, isopropylidene dicthexyl-4,4'- Alicyclic isocyanates such as diisocyanates; 2,4- or 2,6-tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), xylene diisocyanate (XDI), triphenylmethane triisocyanate, tris (4-phenylisocyanate) thiophosphate, tolidine diisocyanate, p-phenylene Aromatic isocyanates such as diisocyanate, diphenyl ether diisocyanate, and diphenylsulfone diisocyanate are listed.

  As the chain extender component, a low molecular weight polyol is used. For example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3 -Butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,4-pentanediol, 1,6-hexanediol , Neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, 2,2-dimethylol heptane, diethylene glycol, 1,4-cyclohexanedimethanol, glycerin, etc .; 1,4-dimethylol Benzene, bisphenol A, ethylene oxide adduct of bisphenol A or pro And aromatic glycols such as alkylene oxide adducts.

  In the present invention, when the thermoplastic polyurethane elastomer (B) contains (a) polysiloxane, specifically, the polysiloxane includes one or more reactive groups in the molecule, such as amino group. And a polysiloxane compound having a reactive group such as a group, an epoxy group, a hydroxyl group, a mercapto group, a carboxyl group, a thiol group, and an isocyanate group. These may be used alone or in combination of two or more.

  The thermoplastic polyurethane-based elastomer (B) containing polysiloxane preferably contains 5 to 40% of polysiloxane as a silicone component in the composition, more preferably 8 to 30%, still more preferably 10 to 20%. contains. When the silicone component content is in the above range, the transparency of the film of the present invention is excellent.

  As a commercial item of the thermoplastic polyurethane-type elastomer (B) containing the said (a) polysiloxane, the "Rezamin PS" series made from a Dainichi Seika Kogyo Co., Ltd. is mentioned, for example, and it can obtain commercially. In addition, you may use these thermoplastic polyurethane-type elastomers individually or in combination of 2 or more types having different compositions.

  In addition, (b) the thermoplastic polyurethane elastomer (B) containing at least one of aliphatic isocyanate and alicyclic isocyanate contains, as an isocyanate component, any one or both of aliphatic isocyanate and alicyclic isocyanate. Is included. The content of the aliphatic isocyanate and the alicyclic isocyanate is preferably 50% by mass or more, more preferably 70% by mass or more, when the total isocyanate component in the thermoplastic polyurethane elastomer (B) is 100% by mass. Preferably it is 90 mass%. In the present invention, those containing aliphatic isocyanate are more preferably used from the viewpoint of transparency.

  When aromatic isocyanate is the main component as the isocyanate component, the average refractive index of the thermoplastic polyurethane elastomer tends to be large, and the refractive index difference from the polylactic acid resin (A) tends to be large. On the other hand, when the main component of the isocyanate is aliphatic isocyanate and / or alicyclic isocyanate, the average refractive index of the obtained thermoplastic polyurethane elastomer can be brought close to the polylactic acid resin (A), and the transparency is good. It becomes.

  In addition, as the thermoplastic polyurethane-based elastomer (B) containing at least one of aliphatic isocyanate and alicyclic isocyanate (b), “Elastollan” manufactured by BASF, “Pandex” manufactured by DIC Covestro Polymer, “Desmopan”, “Texin”, “Milactolan” manufactured by Tosoh Corporation, “Rezamin” manufactured by Dainichi Seika Kogyo Co., Ltd. and the like are commercially available. These may be used alone or in combination of two or more.

  As the method for producing the thermoplastic polyurethane-based elastomer (B) used in the present invention, any conventionally known method can be used.

  The lower limit and the upper limit of the weight average molecular weight of the thermoplastic polyurethane elastomer (B) are not particularly limited, but the lower limit is preferably 30,000 or more, more preferably 40,000 or more, More preferably, 50,000 or more. Moreover, as an upper limit, 1,000,000 or less is preferable, 900,000 or less is more preferable, and 800,000 or less is further more preferable.

  The lower limit value and the upper limit value of the melt viscosity of the thermoplastic polyurethane elastomer (B) are not particularly limited, but as the lower limit value, the shear melt viscosity at a measurement temperature of 200 ° C. and a shear rate of 100 sec-1 is 80 Pa · s or more, preferably 90 Pa · s or more, and more preferably 100 Pa · s or more. The upper limit is preferably 300,000 Pa · s or less, more preferably 200,000 Pa · s or less, and even more preferably 100,000 Pa · s or less.

  The hardness of the thermoplastic polyurethane elastomer (B) is preferably in the range of 60 to 99 in terms of shear A.

<Mixing ratio>
The mixing ratio of the polylactic acid resin (A) and the thermoplastic polyurethane elastomer (B) in the resin composition constituting the I layer of the film of the present invention is (A) / (B) = 97% by mass / 3. It is preferable to set it as mass%-35 mass% / 65 mass%.
The lower limit of the mixing ratio of the thermoplastic polyurethane elastomer (B) is more preferably 5% by mass or more, further preferably 8% by mass or more, and the upper limit is more preferably 35% by mass or less, and further preferably 25% by mass. It is as follows. Further, the lower limit of the mixing ratio of the polylactic acid-based resin (A) is more preferably 65% by mass or more, further preferably 75% by mass or more, and the upper limit is more preferably 95% by mass or less, and further preferably 92% by mass. % Or less.
When the mixing ratio of the thermoplastic polyurethane elastomer (B) is 3% by mass or more, the fracture resistance of the I layer is improved, and even in the film of the present invention having a laminated structure, the lamination is improved by improving the fracture resistance of the I layer. Propagation of breakage to the entire film can be suppressed, and a tensile elongation at break sufficient for the required quality as a heat-shrinkable film can be obtained. Moreover, if the mixing ratio of the thermoplastic polyurethane elastomer (B) is 65% by mass or less, transparency can be satisfied.

<II layer>
The II layer of the present invention is mainly composed of a resin composition comprising a polylactic acid resin (A), a polyolefin resin (C), and a compatibilizer (D). Further, as will be described later, the II layer is arranged as an inner layer.

<Polylactic acid resin (A)>
The polylactic acid resin (A) used in the II layer is the same as that used in the I layer.

<Polyolefin resin (C)>
As the polyolefin resin (C) used in the present invention, conventionally known ones can be appropriately employed and are not particularly limited, but in particular, a flexible polyolefin resin is preferably used. Examples of the flexible polyolefin resin include ethylene / α-olefin copolymer, propylene / α-olefin copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, and ethylene / methacrylic acid copolymer. , Ethylene / acrylic acid ester copolymer, ethylene / methacrylic acid ester copolymer, and the like. These may be used alone or in a mixture of two or more. In the present invention, among them, an ethylene / α-olefin copolymer is preferably used from the viewpoint of transparency and shrinkage characteristics.

The MFR of the polyolefin resin (C) is preferably 0.5 to 20 g / 10 minutes, more preferably 1 to 20 g / 10 minutes, and further preferably 1 to 15 g / 10 minutes.
If MFR is the said range, adjustment of transparency, shrinkage | contraction characteristic, etc. becomes easy, and it is preferable.

The peak temperature of the loss elastic modulus E ″ of the polyolefin resin (C) is preferably −80 to 0 ° C., and the lower limit is more preferably −70 ° C. or higher, and further preferably −60 ° C. or higher. The upper limit is more preferably −10 ° C. or lower, and further preferably −20 ° C. or lower.
If the peak temperature of the loss elastic modulus E ″ is within the above range, the film has a high mechanical strength and is preferable because it does not cause a decrease in stretchability.

  The polyolefin resin (C) has a storage elastic modulus (E ′) at 20 ° C. of preferably 100 MPa or less, more preferably 80 MPa or less, even more preferably when measured under conditions of a vibration frequency of 10 Hz and a strain of 0.1%. 50 MPa or less. The lower limit value of the storage elastic modulus (E ′) is preferably 0.1 MPa or more, more preferably 1.0 MPa or more, and further preferably 3.0 MPa or more in consideration of the whole film stiffness (rigidity at room temperature). . Polyolefin resins having a storage elastic modulus (E ′) at 20 ° C. in the above range have a low crystallinity of polyolefin and a low density, so the average refractive index of the polyolefin resin is also low, and the polylactic acid to be mixed The average refractive index with the resin can be approached. Therefore, the internal haze of the film can be reduced, which is very useful in improving rupture resistance and maintaining transparency. Further, when the storage elastic modulus (E ′) is 100 MPa or less, the effect of improving the rupture resistance is not lowered, and the occurrence of significant appearance defects can be suppressed. On the other hand, it is preferable that the storage elastic modulus (E ′) at 20 ° C. is 0.1 MPa or more because it is possible to prevent the waist of the entire film from greatly decreasing.

Further, the polyolefin resin (C) has a storage elastic modulus (E ′) at 70 ° C. of preferably 50 MPa or less, more preferably 30 MPa or less, still more preferably 20 MPa or less, particularly preferably 10 MPa or less when measured at a vibration frequency of 10 Hz. It can be. The lower limit value of the storage elastic modulus (E ′) at 70 ° C. is preferably 0.1 MPa or more, more preferably 0.5 MPa or more, and further preferably 1.0 MPa or more. When the film of the present invention is used for a shrinkage label of a PET bottle or the like, a heat shrinking process is required as a label attachment process to a covering object such as a PET bottle. In addition, in order to prevent the content from deteriorating, bursting, etc., the heat shrinking process is performed at 60 to 100 ° C. Therefore, the storage elastic modulus (E ′) at 70 ° C. of the polyolefin resin (C) should be 50 MPa or less. For example, the film can exhibit a sufficient heat shrinkage rate in the heat shrink processing temperature region. 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.

  In the present invention, the storage elastic modulus (E ′) can be adjusted, for example, by increasing or decreasing the content of a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. 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.

  The lower limit of the mass average molecular weight of the polyolefin resin (C) 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. Is less than 500,000. 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 production method of the polyolefin resin (C) 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.

  Commercially available products of polyolefin resin (C) include, for example, “Tuffmer” (manufactured by Mitsui Chemicals), “Versify” (manufactured by Dow Chemical), “Vistamax” (manufactured by ExxonMobil), “Elvalloy” (Mitsui -DuPont Polychemical Co., Ltd.).

<Compatibilizer (D)>
In the present invention, the compatibilizing agent (D) is not particularly limited as long as it can compatibilize the polylactic acid resin and the polyolefin resin. Specifically, the reactivity and affinity for the polylactic acid resin are not particularly limited. A resin having both a part having a property and a part having an affinity for a polyolefin resin is preferably used.

  Here, “having reactivity or affinity for polylactic acid resin” means having a functional group having high affinity with polylactic acid resin or a functional group capable of reacting with polylactic acid resin. To do. Examples of functional groups having such properties include acid anhydride groups, carboxylic acid groups, carboxylic acid ester groups, carboxylic acid chloride groups, carboxylic acid amide groups, carboxylic acid groups, sulfonic acid groups, and sulfonic acid ester groups. , Sulfonic acid chloride groups, sulfonic acid amide groups, sulfonic acid groups, epoxy groups, amino groups, imide groups, or oxazoline groups, among others, acid anhydride groups, carboxylic acid groups, or carboxylic acid esters Groups are preferred.

  In addition, the “site having an affinity for the polyolefin resin” means having a chain having an affinity for the polyolefin resin, and more specifically, a linear or branched saturated hydrocarbon moiety as a main chain, or It means having as a block chain and a graft chain.

  Other preferred resins used as the compatibilizer (D) include polyether / polyolefin block copolymers, copolymers of styrene hydrocarbons and conjugated diene hydrocarbons, or hydrogenated resins thereof. It is done. Specific examples of the copolymer of styrene hydrocarbon and conjugated diene hydrocarbon include styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-ethylene-butadiene copolymer, and styrene-ethylene-propylene copolymer. Examples thereof include a polymer and a styrene-ethylene-butylene copolymer.

  In addition, as a commercially available product suitably used as the compatibilizing agent (D), as the acid-modified resin, “Admer” (manufactured by Mitsui Chemicals), “Modic” (manufactured by Mitsubishi Chemical), “Modiper” (NOF) ), “Reseda” (manufactured by Toa Gosei Co., Ltd.), ethylene-ethyl acrylate copolymer, “Lex Pearl EEA” (manufactured by Nippon Polyethylene Co., Ltd.), “Evaflex-EEA” (manufactured by Mitsui DuPont Polychemical Co., Ltd.) ), Ethylene-methyl (meth) acrylic acid copolymer, "Acrylift" (manufactured by Sumitomo Chemical Co., Ltd.), "Nuclele" (manufactured by Mitsui DuPont Polychemical Co., Ltd.), ethylene-vinyl acetate-maleic anhydride copolymer “Bondyne” (manufactured by Arkema), ethylene-glycidyl methacrylate copolymer, ethylene-vinyl acetate-glycidyl methacrylate terpolymer, Eth Bond-first (manufactured by Sumitomo Chemical Co., Ltd.) as a terpolymer of ethyl acrylate-glycidyl methacrylate, manufactured by Sumitomo Chemical Co., Ltd., and Tuftec M (produced by Asahi Kasei Chemicals Co., Ltd.), Epofriend as acid-modified styrene thermoplastic resins (Daicel Co., Ltd.), Copolymers of styrene hydrocarbons and conjugated diene hydrocarbons, or hydrogenated resins such as “Tuftec H” (Asahi Kasei Chemicals), “Clayton” (Clayton Polymer Japan) "Dynalon" (manufactured by JSR), "Septon" (manufactured by Kuraray), "Hiblur" (manufactured by Kuraray), "Tufprene" (manufactured by Asahi Kasei Chemicals), and polyether / polyolefin copolymers include "(Manufactured by Sanyo Chemical Industries).

  In the present invention, a graft copolymer having a thermoplastic resin segment and a segment formed from at least one vinyl monomer, among the above as the compatibilizer (D), Since it is excellent in the effect which makes the polylactic acid-type resin used for II layer of this invention and polyolefin resin compatible, it is used suitably.

  Specific examples of the thermoplastic resin used in the thermoplastic resin segment of the graft copolymer include ethylene-α olefin copolymer rubber, ethylene-α olefin-nonconjugated polyene copolymer rubber, ethylene- ( Examples include a (meth) acrylic acid 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 vinyl monomer used in the segment formed from the vinyl monomer of the graft copolymer include (meth) acrylic acid alkyl esters having an alkyl chain length of 1 to 20 carbon atoms, acid groups Vinyl monomers having a hydroxyl group, vinyl monomers having an epoxy group, vinyl monomers having a cyano group, vinyl monomers having a cyano group, styrene, etc., which are formed from at least one of these It is also possible to use two or more kinds in combination.

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

  Two or more compatibilizers may be used in combination. In that case, the blending ratio is 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. be able to. 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 kinds of compatibilizers are used, the transparency of the film can be improved in order to further promote the compatibility effect between the polylactic acid resin and the polyolefin resin, which is preferable.

<Mass ratio of polylactic acid resin, polyolefin resin and compatibilizer>
In the present invention, the mass ratio of the polylactic acid resin (A), the polyolefin resin (C), and the compatibilizer (D) constituting the II layer is 100% by mass of the resin composition constituting the II layer. On the other hand, the polylactic acid resin (A) is 50% by mass to 96% by mass, the polyolefin resin (C) is 3% by mass to 35% by mass, and the compatibilizer (D) is 1% by mass. It is preferable that it is 15 mass% or less.

  More preferably, the polylactic acid resin (A) is 58% by mass or more and 87% by mass or less, the polyolefin resin (C) is 10% by mass or more and 30% by mass or less, and the compatibilizer (D) is 3% by mass or more. It is 12 mass% or less, More preferably, polylactic acid-type resin (A) is 65 mass% or more and 85 mass% or less, polyolefin resin (C) is 10 mass% or more and 25 mass% or less, Compatibilizing agent (D) Is 5 mass% or more and 10 mass% or less. If the mass ratio of the polyolefin-based resin (C) is 10% by mass or more, the fracture resistance of the film is not significantly reduced, and if it is 35% by mass or less, the I layer adjacent to the II layer The delamination strength can be maintained within a predetermined range. Further, if the mass ratio of the compatibilizing agent (D) 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 increased. It is preferable without inhibiting.

<Other components of layer I and layer II>
Each layer of the film of the present invention may further contain other conventionally known thermoplastic resins as long as the effects of the present invention are not significantly impaired. In addition, recycled resin or the like generated from trimming loss such as ears can be added as appropriate.
Specific examples of other resins include (meth) acrylic acid ester resins, (meth) acrylic acid resins, polyolefin resins, polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, chlorinated polyethylene resins. Resins, polyester resins other than polylactic acid resins, polycarbonate resins, polyamide resins, polyacetal resins, ethylene vinyl acetate copolymers, polymethylpentene resins, polyvinyl alcohol resins, cyclic olefin resins, polybutylene sushi Nate resin, polyacrylonitrile resin, polyethylene oxide resin, cellulose resin, polyimide resin, rigid polyurethane resin, polyphenylene sulfide resin, polyphenylene ether resin, polyvinyl acetal resin, polybutadiene Resin, polybutene resin, polyamideimide resin, polyamide bismaleimide resin, polyarylate resin, polyetherimide resin, polyetheretherketone resin, polyetherketone resin, polyethersulfone resin, polyketone resin Examples thereof include resins, polysulfone resins, aramid resins, silicone resins, and the like, and copolymers containing these resins as main components, core-shell multilayer polymers, and modified products thereof.
Among these, (meth) acrylic ester resin, ethylene vinyl acetate copolymer, polybutylene succinate resin, polyethylene oxide resin, and polyvinyl acetal resin are excellent in compatibility with polylactic acid resin, Blending with a polylactic acid-based resin is effective for adjusting the glass transition temperature that affects shrinkage characteristics, and for imparting further fracture resistance by being finely dispersed in the polylactic acid-based resin.
Moreover, you may add suitably the additive generally used in each layer of the film of this invention in the range which does not inhibit the effect of this invention remarkably. Examples of the additives include inorganic particles such as silica, talc, kaolin and calcium carbonate, pigments such as titanium oxide and carbon black, flame retardants, weather resistance stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, and crosslinks. Additives such as additives, lubricants, nucleating agents, plasticizers, anti-aging agents, antioxidants, light stabilizers, UV absorbers, neutralizing agents, antifogging agents, anti-blocking agents, slip agents, and coloring agents. .

<Layer structure>
The film of the present invention may be any film as long as the I layer and the II layer have at least three layers laminated in the order of I / II / I, and other layers may be added as necessary. Absent. In the present invention, by arranging the I layer on the front and back layers and the II layer on the inner layer, it is possible to achieve excellent transparency and to obtain a film property balance such as excellent fracture resistance, In addition, when a heat-shrinkable film is used, excellent shrinkage characteristics can be realized.

  The thickness ratio of each layer may be set in consideration of the above-described effects, and is not particularly limited, but the thickness ratio of the I layer to the entire film thickness is preferably 10% or more, more preferably 15 %, More preferably 20% or more, and the upper limit of the thickness ratio is preferably 70% or less, more preferably 60% or less, and even more preferably 50% or less. The thickness ratio of the II layer to the thickness of the entire film is preferably 20% or more, more preferably 25% or more, still more preferably 30% or more, and the upper limit is preferably 90% or less, more preferably 85% or less, More preferably, it is 80% or less. If the thickness ratio of the I layer to the entire film is within the above range, the surface roughness of the II layer can be suppressed, and a film having excellent transparency and gloss can be obtained. Further, if the thickness ratio of the II layer to the total film thickness is within the above range, a film having excellent rupture resistance can be obtained. Especially when a heat shrinkable film is used, shrink wrap, shrink bundle wrap and shrink A heat-shrinkable laminated film suitable for applications such as labels can be obtained with a good balance.

  The total thickness of the film or heat-shrinkable film of the present invention is not particularly limited, but is preferably thinner from the viewpoints of transparency, shrinkage workability, raw material cost, and the like. Specifically, the total thickness of the film is preferably 80 μm or less, more preferably 70 μm or less, and still more preferably 60 μm or less. The lower limit of the total thickness of the film is not particularly limited, but is preferably 20 μm or more in consideration of handling properties and the like.

<The manufacturing method of the film of this invention>
The method for producing the film of the present invention is not particularly limited, and a conventionally known method can be adopted. Specifically, for example, a resin is melt-kneaded using an extruder or the like to form a pellet, and then a film is formed by a T-die method, a tubular method, a press method, or the like. Examples of the laminating method include a co-extrusion method, a method of forming a film of each layer, then superposing and heat-sealing, a method of bonding with an adhesive, and the like.

<Method for producing heat-shrinkable film>
The method of using the film of the present invention as a heat-shrinkable film is not particularly limited, and a conventionally known method can be employed. 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 heat-shrinkable film of the present invention may be subjected to surface treatment and surface treatment such as corona treatment, printing, coating, and vapor deposition, as well as bag making processing and perforation processing using various solvents and heat sealing. Can be applied.

  The heat-shrinkable film of the present invention can be processed into a cylindrical shape or the like from a flat surface by an article to be packaged 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 adhesion method using an organic solvent, a method using a heat seal, a method using an adhesive, and a method using an impulse carrier are conceivable. Among these, from the viewpoint of productivity and appearance, an adhesion method using an organic solvent is preferably used.

<Heat shrinkage>
In the heat-shrinkable film of the present invention, the heat shrinkage rate in the main shrinkage direction when immersed in warm water at 80 ° C. for 10 seconds is preferably 20% or more and 80% or less, and the lower limit is 30% or more. The upper limit is more preferably 70% or less.
In order to set the heat shrinkage rate within the above range, the stretching speed, stretching temperature, stretching ratio, and temperature and time in heat treatment and relaxation treatment in the stretching step in the method for producing a heat shrinkable film of the present invention described later are described. , And can be adjusted by stretching conditions such as alicyclic ratio.

  The “heat shrinkage rate” in the present invention is the percentage of shrinkage with respect to the original size before shrinkage in% in the longitudinal direction or the transverse direction, as will be described later. Further, the “main shrinkage direction” means the larger one of the longitudinal direction and the transverse direction in the stretching direction, and is a direction corresponding to the outer circumferential direction when the bottle is attached to a bottle, for example.

  The shrinkage rate in the main shrinkage direction serves as an index for determining adaptability to a shrinkage processing step in a relatively short time (several seconds to about several tens of seconds), such as for use as a shrinkage label for a PET bottle. 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 shrinkage appearance without spots, wrinkles and avatars, and the upper limit of the heat shrinkage rate in the main shrinkage direction of the film when immersed in warm water at 80 ° C. for 10 seconds is In order to suppress rapid shrinkage of the film, it is more preferably 80% or less.

  When the heat-shrinkable film of the present invention is used as a heat-shrinkable label, the heat shrinkage rate in the direction orthogonal to the main shrinkage direction when immersed in warm water at 80 ° C. for 10 seconds is −10% or more. 10% or less (negative shrinkage means that the film has expanded after immersion in hot water, and in the case of a uniaxially stretched film, it may be observed in the measurement of the heat shrinkage in the direction perpendicular to the main shrinkage direction. .), More preferably from −8% to 8%, even more preferably from −5% to 5%. If the film has a thermal shrinkage rate of -10% or more and 10% or less in the direction perpendicular to the main shrinkage direction, the dimensional change in the direction perpendicular to the main shrinkage direction after shrinkage is small, and the printed pattern and characters after shrinkage are distorted. In addition, it is preferable because the vertical pulling phenomenon is less likely to occur when mounted on a container.

<Transparency: All haze>
When the transparency of the film of the present invention is measured in accordance with JIS K7136, the total haze value is preferably 10% or less, more preferably 8% or less, and further preferably 7% or less. preferable. If the total haze value is 10% or less, it is possible to sufficiently ensure the visibility of the covering on which the film is attached and the back surface printing.

<Transparency: Internal haze>
When the transparency of the film of the present invention is measured in accordance with JIS K7136, the internal haze value is preferably 10% or less, more preferably 8% or less, and further preferably 6% or less. preferable. If the internal haze value is 10% or less, it is possible to sufficiently ensure the visibility of the covering on which the film is attached and the back surface printing.

<Tensile rupture elongation>
The fracture resistance of the film of the present 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, the film of the present invention has an elongation of 100% or more, preferably 200% or more, more preferably 300% in the film take-off (flow) direction (MD) in a tensile test under a 23 ° C. environment, particularly for label applications. That is all. 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. Also, 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 100% or more, so that it is difficult to break.

<The molded product of the present invention, the label of the present invention, and the container of the present invention>
The use of the heat-shrinkable film of the present invention is not particularly limited, but by using this as a base material, a printing layer, a vapor deposition layer, and other functional layers are laminated as necessary to form a bottle. (Blow bottle), tray, lunch box, sugar beet container, dairy product container, and other various molded products.

  Moreover, the heat-shrinkable film of the present invention can be used as a base material for heat-shrinkable labels for food containers (for example, soft drinks or food PET bottles, glass bottles, preferably PET bottles). In this case, even a complicated shape (for example, a cylinder with a narrow center, a square column with a corner, a pentagonal column, a hexagonal column, etc.) can be closely attached to the shape and is mounted beautifully without wrinkles or avatars. Label. And the food container equipped with this label can be used as a container. In addition, the said molded article and container can be produced by using a normal shaping | molding method.

  In addition, since the label of the present invention has excellent low temperature shrinkage and shrink finish, in addition to the heat shrinkable label material of a plastic molded product that deforms when heated to a high temperature, it has a 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 label material for a plastic package (container) using at least one selected from a polyester resin such as a polyester resin 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.

  As described above, the film of the present invention has been described using a heat-shrinkable film as a representative example. However, the use of the film of the present invention is not limited to a heat-shrinkable film, for example, various packaging films, various industrial films, medical use, It is also useful to use it as a base material for building materials, electrical / electronic equipment, information recording films, sheet materials, labels, adhesive tapes, and the like.

  Examples are shown below, but the present invention is not limited by these examples.

<Evaluation method>
Measurement and evaluation shown in the examples were performed as follows. In the examples, the film take-up (flow) direction 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 10 mm in length and 200 mm in width and immersed in a hot water bath at 80 ° C. for 10 seconds, and the amount of shrinkage was measured. The thermal shrinkage rate was expressed as a percentage of the shrinkage amount relative to the original size before shrinkage.
○: When the heat shrinkage rate at 80 ° C. is 20% or more and 70% or less ×: When the heat shrinkage rate at 80 ° C. is less than 20% or more than 70%

(2) Tensile elongation at break The resulting heat-shrinkable film was cut into a size of 110 mm in the direction perpendicular to the main shrink direction (longitudinal direction, MD) and 15 mm in the main shrink direction, and in accordance with JIS K7127. At 200 mm / min, measure the tensile elongation at break in the direction (longitudinal direction, MD) perpendicular to the main shrinkage direction of the film at an ambient temperature of 23 ° C./0° C., and measure the average value of 10 measurements. Judgment was made based on the following criteria.
23 ° C tensile elongation at break (longitudinal direction, MD)
◯: When the tensile breaking elongation is 200% or more Δ: When the tensile breaking elongation is 100% or more ×: When the tensile breaking elongation is less than 100% 0 ° C. tensile breaking elongation (longitudinal direction, MD )
○: When the tensile breaking elongation is 150% or more Δ: When the tensile breaking elongation is 100% or more ×: When the tensile breaking elongation is less than 100%

(3) Total haze The total heat haze value of the obtained heat-shrinkable film was measured according to JIS K7136, and judged according to the following criteria.
○: When all haze values are 10% or less ×: When all haze values exceed 10%

(4) Internal haze The obtained heat-shrinkable film was measured in accordance with JIS K7136, the internal haze value was determined based on the following criteria.
○: When the internal haze value is 10% or less ×: When the internal haze value exceeds 10%

<Materials used>
(Polylactic acid resin (A))
-Product made from Nature Works LLC, a brand name: NatureWorks4043D, D body / L body weight = 4.25 / 95.75, and it abbreviates as "A-1."
-Product made from Nature Works LLC, a brand name: NatureWorks4060D, D body / L body weight = 12/88, It abbreviates as "A-2."
-Product made from Nature Works LLC, brand name: NatureWorks4032D, D body / L body weight = 1.2 / 98.8, It abbreviates as "A-3."

(Thermoplastic polyurethane elastomer (B))
・ Product name: Resamine PS22470, manufactured by Dainichi Seika Kogyo Co., Ltd., isocyanate component: aromatic isocyanate, polyol component: polyether polyol, silicone component content: 16%, abbreviated as “B-1”.
-Tosoh Corporation product name: Milactolan XN-2001, isocyanate component: aliphatic isocyanate, polyol component: polycarbonate polyol, abbreviated as “B-2”.

(Polyolefin resin (C))
-Mitsui Chemicals, brand name: Toughmer A4050S, polyethylene resin (ethylene / butene-1 = 72.4 / 27.6), abbreviated as "C-1."

(Compatibilizer (D))
-JSR Co., Ltd., trade name: Dynalon 8660P, modified styrene elastomer, hereinafter abbreviated as “D-1”.
-Asahi Kasei Chemicals, product name: Tuftec M1943, modified styrene elastomer, hereinafter abbreviated as "D-2".
-NOF Corporation, trade name: Modiper A5200, (ethylene-ethyl acrylate) -methyl methacrylate graft copolymer (= 70/30), hereinafter abbreviated as "D-3".

(Examples and Comparative Examples)
As shown in Table 1, 69% by mass of polylactic acid resin (A-1), 21% by mass of polylactic acid resin (A-2), 5% by mass of polylactic acid resin (A-3), thermoplastic polyurethane After blending the elastomer (B-1) in a proportion of 5% by mass, charging it into a twin screw extruder (screw diameter: 35 mmφ), melting and mixing at a set temperature of 200 ° C., and extruding from a strand die at a set temperature of 200 ° C. The resin composition cooled in the water tank was cut with a strand cutter to obtain pellets, which were used for the investigation shown in Example 1 described later (referred to as I layer resin (1)).
Moreover, 65 mass% of polylactic acid-type resin (A-1) shown in Table 1, 20 mass% of polylactic acid-type resin (A-2), 5 mass% of polylactic acid-type resin (A-3), heat | fever Except for changing the plastic polyurethane elastomer (B-1) to 10% by mass, pellets were obtained in the same manner as in the I-layer resin (1), and used for the study shown in Example 2 described later (I (Referred to as layer resin (2)).
Moreover, 69 mass% of polylactic acid-type resin (A-1) shown in Table 1, 21 mass% of polylactic acid-type resin (A-2), 5 mass% of polylactic acid-type resin (A-3), heat | fever Except for changing the plastic polyurethane elastomer (B-2) to 5% by mass, pellets were obtained in the same manner as in the I-layer resin (1), and used in the study described in Example 3 (I). (Referred to as layer resin (3)).
Moreover, 65 mass% of polylactic acid-type resin (A-1) shown in Table 1 and 2, 20 mass% of polylactic acid-type resin (A-2), and 5 mass% of polylactic acid-type resin (A-3) are shown. Except that the thermoplastic polyurethane elastomer (B-2) was changed to 10% by mass, pellets were obtained in the same manner as the I-layer resin (1), and Examples 4 and 7 to 9 described later were obtained. , Comparative Examples 1 to 3 and Reference Example 1 were used (referred to as I layer resin (4)).
Moreover, 58 mass% of polylactic acid-type resin (A-1) shown in Table 1, 17 mass% of polylactic acid-type resin (A-2), 5 mass% of polylactic acid-type resin (A-3), heat | fever Except for changing the plastic polyurethane elastomer (B-2) to 20% by mass, pellets were obtained in the same manner as in the I-layer resin (1) and used for the study shown in Example 5 (I (Referred to as layer resin (5)).
Moreover, 27 mass% of polylactic acid-type resin (A-1) shown in Table 1, 8 mass% of polylactic acid-type resin (A-2), 5 mass% of polylactic acid-type resin (A-3), heat | fever Except for changing the plastic polyurethane elastomer (B-2) to 60% by mass, pellets were obtained in the same manner as in the I-layer resin (1), and used for the study shown in Example 6 described later (I (Referred to as layer resin (6)).

Moreover, 52 mass% of polylactic acid-type resin (A-1) shown in Table 1, 28 mass% of polylactic acid-type resin (A-2), 15 mass% of polyolefin-type resin (C-1), and compatibilization Except that the agent (D-1) was changed to 5% by mass, pellets were obtained by the same method as that for the above I-layer resin (1), and used for the studies shown in Examples 1 to 6 described later (II layer) Resin (referred to as (1)).
Moreover, 58 mass% of polylactic acid-type resin (A-1) shown in Table 1, 32 mass% of polylactic acid-type resin (A-2), 5 mass% of polyolefin-type resin (C-1), and compatibilization Except that the amount of the agent (D-1) was changed to 5% by mass, pellets were obtained by the same method as that for the I-layer resin (1) and used for the investigation shown in Example 7 (II-layer resin). (Referred to as (2))
Moreover, 52 mass% of polylactic acid-type resin (A-1) shown in Table 1, 28 mass% of polylactic acid-type resin (A-2), 15 mass% of polyolefin-type resin (C-1), and compatibilization Except that the agent (D-2) was changed to 5% by mass, pellets were obtained by the same method as that for the I-layer resin (1) and used for the investigation shown in Example 8 (II-layer resin). (Referred to as (3)).
Moreover, 52 mass% of polylactic acid-type resin (A-1) shown in Table 1, 28 mass% of polylactic acid-type resin (A-2), 15 mass% of polyolefin-type resin (C-1), and compatibilization Except that the agent (D-3) was changed to 5% by mass, pellets were obtained by the same method as that for the I-layer resin (1) and used for the study shown in Example 9 (II-layer resin). (Referred to as (4)).
Moreover, 36 mass% of polylactic acid-type resin (A-1) shown in Table 2, 19 mass% of polylactic acid-type resin (A-2), 40 mass% of polyolefin-type resin (C-1), compatibilizing agent Except that (D-1) was changed to 5% by mass, pellets were obtained in the same manner as in the above I-layer resin (1) and used for the investigation shown in Comparative Example 1 described later (II-layer resin ( 5)).
Moreover, it changed to 55 mass% of polylactic acid-type resin (A-1) shown in Table 2, 30 mass% of polylactic acid-type resin (A-2), and 15 mass% of polyolefin-type resin (C-1). Except for the above, pellets were obtained in the same manner as in the above-mentioned I-layer resin (1) and used for the investigation shown in Comparative Example 2 described later (referred to as II-layer resin (6)).
Moreover, it is the same as that of the said resin for I layers (1) except having changed polylactic acid-type resin (A-1) to 65 mass% and polylactic acid-type resin (A-2) to 35 mass% shown in Table 2. Pellets were obtained by the above method and used for the investigation shown in Comparative Example 3 described later (referred to as II layer resin (7)).

Example 1
Single-screw extrusion that forms II layer in equipment capable of co-extrusion of I layer / II layer / I layer with two single-screw extruders (Mitsubishi Heavy Industries) and two types of three-layer multi-manifold die Introduce the pelletized II-layer resin (1) into the machine, introduce the I-layer resin (1) into the single-screw extruder that forms the I layer, and melt mix at each extruder set temperature 200 ° C Thereafter, the layers are coextruded so that the thickness of each layer is I layer / II layer / I layer = 25 μm / 150 μm / 25 μm, taken up by a cast roll at 50 ° C., cooled and solidified, and unstretched laminate having a width of 200 mm and a thickness of 200 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 preheating 82 ° C., stretching 82 ° C., heat treatment 82 ° C., preheating 1 zone, stretching 2 zone, and heat treatment 3 zone. Thus, a heat-shrinkable film having a thickness of 40 μm was obtained. The evaluation results of the obtained film are shown in Table 1.

(Example 2)
As shown in Table 1, a heat-shrinkable film was obtained in the same manner as in Example 1 except that the I-layer resin (1) in Example 1 was changed to the I-layer resin (2). The evaluation results of the obtained film are shown in Table 1.

(Examples 3 to 6)
As shown in Table 1, a heat-shrinkable film was obtained in the same manner as in Example 1 except that the I-layer resin (1) in Example 1 was changed to I-layer resins (3) to (6), respectively. Got. The evaluation results of the obtained film are shown in Table 1.

(Example 7)
As shown in Table 1, except that the I layer resin (1) in Example 1 was changed to the I layer resin (4) and the II layer resin (1) was changed to the II layer resin (2). In the same manner as in Example 1, a heat-shrinkable film was obtained. The evaluation results of the obtained film are shown in Table 1.

(Example 8)
As shown in Table 1, except that the I layer resin (1) in Example 1 was changed to the I layer resin (4) and the II layer resin (1) was changed to the II layer resin (3). In the same manner as in Example 1, a heat-shrinkable film was obtained. The evaluation results of the obtained film are shown in Table 1.

Example 9
As shown in Table 1, except that the I layer resin (1) in Example 1 was changed to the I layer resin (4) and the II layer resin (1) was changed to the II layer resin (4). In the same manner as in Example 1, a heat-shrinkable film was obtained. The evaluation results of the obtained film are shown in Table 1.

(Comparative Example 1)
As shown in Table 2, the I layer resin (1) in Example 1 was changed to the I layer resin (4), and the II layer resin (1) was changed to the II layer resin (5). A laminated film was formed in the same manner as in Example 1. The sheet extruded between the die and the cast roll was greatly necked in, and a good sheet could not be obtained.

(Comparative Example 2)
As shown in Table 2, the I layer resin (1) in Example 1 was changed to the I layer resin (4), and the II layer resin (1) was changed to the II layer resin (6). In the same manner as in Example 1, a heat-shrinkable film was obtained. The evaluation results of the obtained film are shown in Table 2.

(Comparative Example 3)
As shown in Table 2, except that I layer resin (1) in Example 1 was changed to I layer resin (4) and II layer resin (1) was changed to II layer resin (7). In the same manner as in Example 1, a heat-shrinkable film was obtained. The evaluation results of the obtained film are shown in Table 2.

(Reference Example 1)
As shown in Table 2, the I layer resin (1) in Example 1 was changed to the I layer resin (4), and the II layer resin (1) was changed to the I layer resin (4). In the same manner as in Example 1, a heat-shrinkable film was obtained. The evaluation results of the obtained film are shown in Table 2.

  As shown in Table 1, regarding the films obtained in Examples 1 to 9, the transparency seen from all haze and internal haze was good. Also, the tensile elongation at break of the MD of the film showed good values at both 23 ° C. and 0 ° C. On the other hand, as shown in Table 2, when a polyolefin resin having a mass ratio exceeding the range specified by the present invention is used for the II layer (Comparative Example 1), extreme neck-in occurs during film formation, which is good. The sheet could not be formed. Further, when the compatibilizer was not added to the II layer (Comparative Example 2), when the polyolefin resin and the compatibilizer were not added to the II layer (Comparative Example 3), the composition of the II layer was changed substantially. In addition, in the case of a single-layer film-like composition with the I layer composition (Reference Example 1), although the transparency was good, the tensile elongation at break at 0 ° C. was inferior. As described above, when the tensile elongation at break at low temperature is insufficient, there is a risk that the film breaks when the line speed is increased in a process such as a printing process.

  The film of the present invention is excellent in transparency and rupture resistance, and has a wide range of fields of use. In particular, it can be suitably used for heat shrinkable films, heat shrinkable labels, and the like.

Claims (10)

An I layer comprising a resin composition comprising a polylactic acid resin (A) and a thermoplastic polyurethane elastomer (B), a polylactic acid resin (A), a polyolefin resin (C), and a compatibilizer (D) A laminated film composed of at least three layers laminated in the order of I / II / I, wherein the thermoplastic polyurethane elastomer (B) is: A polylactic acid-based laminated film characterized by satisfying at least one of (a) and (b).
(A) containing polysiloxane (b) containing at least one of aliphatic isocyanate and alicyclic isocyanate   The content of the thermoplastic polyurethane elastomer (B) in the resin composition constituting the I layer is 3% by mass or more and 65% by mass or less when the entire resin composition is 100% by mass. The polylactic acid-based laminated film according to claim 1.   In the resin composition constituting the II layer, when the total resin composition is 100 mass%, the polylactic acid resin (A) is 50 mass% to 96 mass%, and the polyolefin resin (C) is 3 mass%. The polylactic acid-based laminated film according to claim 1 or 2, wherein the polylactic acid-based laminated film contains 35% by mass or less and a compatibilizer (D) of 1% by mass to 15% by mass.   The compatibilizer (D) is a graft copolymer having a thermoplastic resin segment and a segment formed from at least one vinyl monomer. The polylactic acid-type laminated film in any one.   The polylactic acid-based laminated film according to any one of claims 1 to 4 is stretched in at least one direction, and has a heat shrinkage ratio of 20% or more and 80% in the main shrinkage direction when immersed in warm water at 80 ° C for 10 seconds. A heat-shrinkable laminated film characterized by:   6. The heat-shrinkable laminated film according to claim 5, wherein the total haze value based on JIS K7136 is 10% or less.   The heat-shrinkable laminated film according to claim 5 or 6, wherein an internal haze value based on JIS K7136 is 10% or less.   A molded article using the heat-shrinkable laminated film according to claim 5 as a base material.   A heat-shrinkable label using the heat-shrinkable laminated film according to claim 5 as a substrate.   A container equipped with the molded article according to claim 8 or the heat-shrinkable label according to claim 9.