JP5160257B2 - Heat-shrinkable film, molded article using the heat-shrinkable film, heat-shrinkable label, and container using or fitted with the molded article - Google Patents

Description

  The present invention relates to a heat-shrinkable film, a molded article using the heat-shrinkable film, a heat-shrinkable label, and a container equipped with the molded article or the label, and more specifically, excellent in shrinkage characteristics and heat resistance. Furthermore, heat shrinkable films suitable for applications such as shrink wrapping, shrink-bound wrapping, and shrink labels, as well as molded products using the heat shrinkable films, heat shrinkable labels, and molded products using or the labels Relates to a container equipped with.

  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.

  On the other hand, the effective use of exhaustible resources has recently been emphasized, and the use of renewable resources has become an important issue. Currently, the most noticeable solution is the use of plant-based plastics. This plant-derived plastic not only uses non-depleted resources, but can save exhaustible resources during plastic production, and also has excellent recyclability.

  Among these plant-derived plastics, 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 for polyester (polyethylene terephthalate), it has attracted attention in the field of film packaging materials and injection molding.

  However, when polylactic acid is used as a material for heat-shrinkable labels, it is rigid at room temperature, has low-temperature shrinkability, and has good natural shrinkage, but it is a very brittle material. There is a problem that sometimes contraction 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 comprising a polyester plasticizer (see Patent Document 10), a biodegradable resin composition comprising a polylactic acid and an epoxidized diene block copolymer (see Patent Document 11), polylactic acid , A lactic acid polymer composition comprising an aliphatic polyester and polycaprolactone (Patent Document 12), crystalline polylactic acid and natural rubber And at least one of the polylactic acid-based resin composition comprising a 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) in which a graph obtained by graft polymerization of a rubber-like polymer and a vinyl-based single substance to a polylactic acid resin and a copolymer has been proposed (see Patent Document 15). Is not enough.
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 09-316310 A Japanese Patent Laid-Open No. 5-179110 JP-A-10-251498 JP 2000-191895 A JP 2000-219803 A JP 2001-031853 A JP 2003-183488 A JP 2003-286400 A JP 2004-285258 A

  The present invention has been made in view of the above-mentioned problems, and the problems of the present invention are low in environmental load, excellent in heat shrinkage characteristics, impact resistance, transparency, mechanical characteristics, and shrinkage finish, and shrinkage. The object is to obtain a heat-shrinkable film suitable for applications such as packaging, shrink-bound packaging and shrink labels.

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

  The subject of the present invention comprises a mixed resin containing a polylactic acid resin and a polyolefin resin as main components, and a mass ratio of the polylactic acid resin to the polyolefin resin of 95/5 to 50/50, Or having at least one mixed resin layer, wherein the polylactic acid resin is composed of a copolymer of D-lactic acid and L-lactic acid, or a mixed resin of this copolymer, and D-lactic acid and L-lactic acid. The D / L ratio is 3/97 to 15/85 or 85/15 to 97/3, and the polyolefin resin has a vibration frequency of 10 Hz and a strain of 20 ° C. when measured under the conditions of 0.1% strain. The heat shrinkability of which the storage elastic modulus (E ′) is 100 MPa or less, the film is stretched in at least one direction, and immersed in 80 ° C. warm water for 10 seconds, the heat shrinkage in the main shrinkage direction of the film is 20% or more. Film (hereinafter, Can be solved by using of the present invention ".).

  In addition, the other problems of the present invention can be solved by a molded product using the film according to the present invention as a base material, a heat-shrinkable label, and a container using or mounting this molded product. it can.

  According to the present invention, since a stretched film having a predetermined heat shrinkage rate, which is formed of a mixed resin containing a polylactic acid resin and a polyolefin resin at a predetermined ratio, is used, heat shrinkage characteristics, impact resistance, Excellent mechanical properties and shrink finish.

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

  Hereinafter, the heat-shrinkable film, molded product, heat-shrinkable label, and container equipped with the molded product or heat-shrinkable label according to the present invention (hereinafter referred to as “the film of the present invention” and “the molded product of the present invention”, respectively) , “The label of the present invention” and “the container of the present invention”).

  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.

[Film of the present invention]
The film of the present invention comprises a heat-shrinkable film made of a mixed resin containing a polylactic acid resin and a polyolefin resin as main components.

<Polylactic acid resin>
The polylactic acid resin used in the film of the present invention refers to a homopolymer of D-lactic acid or L-lactic acid, or a copolymer thereof. Specifically, a 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. A mixed resin of a plurality of the above copolymers having different copolymerization ratios with L-lactic acid is also included.

  The copolymer of L-lactic acid and D-lactic acid 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, preferably 5/95 to 15/85, or 85/15 to 95/5, and 8/92 to 15/85, or 85/15 to 92/8 More preferred is 10/90 to 15/85, or most preferred is 85/15 to 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 film of the present 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, and the like as a small amount of a copolymerization component as long as the essential properties of the PLA resin are not impaired. 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, and the more preferable the rigidity and transparency. The copolymerization ratio is preferably determined in consideration of a balance of physical properties such as impact resistance. Further, it is preferable to copolymerize at a ratio not exceeding the range of the Vicat softening point described later. 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, 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.

  Representative examples of polylactic acid resins preferably used in the present invention include “Lacia” manufactured by Mitsui Chemicals, “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 or graft copolymer. Examples include “Plamate” (manufactured by Dainippon Ink & Chemicals, Inc.).

<Polyolefin resin>
The polyolefin resin used in the film of the present 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 ′) at 20 ° C. of the film of the present invention in 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 it can achieve reducing the internal haze of the film of this invention, 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 film of the present invention is 0.1 MPa or more, it is possible to prevent the waist of the entire film from greatly decreasing.

  Furthermore, the polyolefin resin used in the film of the present invention 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, more preferably when measured at a vibration frequency of 10 Hz. Is 10 MPa. 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, more 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. 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 70 ° C. storage elastic modulus (E ′) of the polyolefin resin used in the film of the present invention is 50 MPa or less, the film can exhibit a sufficient heat shrinkage rate in the heat shrinkage 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.

  In the film of the present invention, the storage modulus (E ′) can be adjusted by increasing or decreasing the content of a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, which will be described later. 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, and conversely the storage elastic modulus (E ′) is increased. In the case of lowering, it can be adjusted by increasing the content of a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms.

  In the film of the present invention, the polyolefin 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 viewpoints of adjusting the storage elastic modulus (E ′) at 70 ° C. to a predetermined range, and from the viewpoints of heat shrinkage properties, mechanical properties, and moldability, polyethylene resins, polypropylene resins, or these It is preferable to use a mixture.

  Below, the preferable polyethylene-type resin and polypropylene-type resin which are used with the film of this invention are illustrated.

  Examples of the polyolefin resin used in the film of the present invention include polyethylene resins, polypropylene resins, ethylene-based 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 film of the present 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 film of the present invention, the polyolefin 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, the films of the present 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. On the other hand, if the density is 0.800 g / cm ³ or more, the waist (rigidity at room temperature) and the heat resistance of the whole film are not significantly lowered, which is 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 film of the present 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)," Moretec "(Idemitsu Kosan)," UBE Polyethylene "" UMERIT "(Ube Industries)," NUC It is commercially available as “polyethylene”, “Nackflex” (manufactured by Nihon Unicar), “engage” (manufactured by Dow Chemical).

  Also, as polypropylene resins, the product 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), and the like. These copolymers can be used alone or in admixture of two or more.

  Moreover, the film of this invention can also use the copolymer with the monomer copolymerizable with the said ethylene further as 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” (Dainippon Ink Chemical Co., Ltd.). Kogyo Co., Ltd.) and “Evaate” (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.).

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

  The polyolefin resin used in the film of the present invention has a lower limit of mass average molecular weight of 50,000, preferably 100,000, and an upper limit of 700,000, preferably 600,000, more preferably 500,000. 000 is preferred. 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.

<Mass ratio of polylactic acid resin and polyolefin resin>
In the film of the present invention, it is important that the mass ratio of the polylactic acid resin and the polyolefin resin is 95/5 to 50/50. The mass ratio is more preferably 90/10 to 60/40, and still more preferably 85/15 to 70/30. By setting the mass ratio of the polyolefin resin to the polylactic acid resin to 5 or more, the effect of improving the fracture resistance can be expected. On the other hand, the waist of the whole film can be maintained by keeping the mass ratio of the polyolefin resin to the polylactic acid resin at 50 or less.

<Additives to mixed resin>
Furthermore, in the film of the present invention, in the mixed resin, a (meth) acrylic resin, a polyethylene resin, a polypropylene resin, a polystyrene resin (in addition to the polyolefin resin) as long as the effects of the present invention are not significantly impaired. 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 other thermoplastic resins such as polyamide resins and polyoxymethylene resins can be further contained.

  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 film of the present 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, and 30% by mass or less, preferably 25% by mass or less, more preferably. It is 20 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 film of the present invention, the above-mentioned mixed resin is a flexible resin for the purpose of improving impact resistance, transparency, molding processability and various properties of the 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, copolymers of diol, dicarboxylic acid, and lactic acid resins, and core-shell structure rubbers.

  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 film of the present 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 polyester resin suitably used in the film of the present invention preferably has a melting point of 100 ° C. or higher and 170 ° C. or lower. Even in the range of 60 ° C. to 100 ° C. in which normal shrinkage is performed by adjusting the melting point to that range, the aliphatic polyester resin can maintain a crystalline state, and as a result, plays a role like a column during shrinkage. By carrying it, it becomes 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% by mass or more, and 30% by mass or less, preferably 25% by mass or less. More preferably, it is 20 mass% or less.

  Further, as the core-shell structure rubber, the following can be used more suitably. Of those having a core-shell structure, a silicone acrylic composite rubber is particularly preferably used. As a specific example, the core part is made of a copolymer of a siloxane compound and a (meth) acrylic monomer, and the shell part is made of a homopolymer or copolymer of a (meth) acrylic monomer. Is mentioned. Examples of the siloxane compound include dimethylsiloxane. Moreover, as a (meth) acrylic-type monomer used for a core part, butyl (meth) acrylate, 2-ethylhexyl acrylate, etc. are mentioned. Furthermore, examples of the (meth) acrylic monomer used for the shell part include methyl (meth) acrylate.

  The content of the core-shell structured rubber is 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, and 30% by mass or less, preferably 25% with respect to the total amount of the resin constituting the film. It is at most 20% by mass, more preferably at most 20% by mass.

  In the film of the present invention, for the purpose of improving various properties of the impact resistance, transparency, molding processability 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, dibutyldi 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 the film of this invention>
The film of the present invention can be produced by a known method using the 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 film of the present invention may be subjected to surface treatment or surface treatment such as corona treatment, printing, coating, vapor deposition, and bag making processing or perforation processing using various solvents or heat sealing, as necessary. it can.

<Film structure>
The layer structure of the film of the present invention may be a single layer, or other film for the purpose of imparting surface functional properties such as slipperiness, heat resistance, solvent resistance, and easy adhesion to the film surface. A stacked structure in which layers are stacked may be used. That is, it may be a laminate having at least one mixed resin layer. For example, as shown in FIG. 1 (A), a film made of a single layer of the layer (I) made of the mixed resin of the present invention may be used. Moreover, as shown to FIG. 1 (B), the film provided with the layer structure which laminated | stacked layer (II) from which a resin composition or an additive differs on layer (I) which consists of mixed resin of this invention may be sufficient. Further, as shown in FIGS. 2A, 2B, and 2C, layers (I) and (III) having different resin compositions or additives are added to the layer (I) made of the mixed resin of the present invention. (II) / (I) / (II), (II) / (I) / (III), (II) / (I) / (III) / (II) Examples of laminated films are given. In this case, the lamination ratio of each layer can be appropriately adjusted according to the application and purpose.

  In the film of the present invention, the preferred layer structure is when the layer (II) is a layer containing a polylactic acid resin as a main component. In particular, the D / L ratio of the polylactic acid resin constituting the layer (II) is preferably different from the D / L ratio constituting the layer (I). By adjusting the D / L ratio and changing the crystallinity in the layer (I) and the layer (II), better shrink finish can be realized.

  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.

  The total thickness of the film of the present invention is not particularly limited, whether it is a single layer or a laminate, 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 50 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 film of the present 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, 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 film of the present invention is used as a heat-shrinkable label, the heat shrinkage rate in the direction orthogonal to the main shrinkage direction is preferably 10% or less when immersed in warm water at 80 ° C. for 10 seconds, It is more preferably 5% or less, and further preferably 3% or less. If the film has a thermal shrinkage rate of 10% or less in the direction perpendicular to the main shrinkage direction, the dimension itself in the direction perpendicular to the main shrinkage direction after shrinkage may be shortened, or the printed pattern or character distortion after shrinkage may occur. In the case of a square bottle, it is preferable because troubles such as vertical sink are unlikely to occur.

  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)
Regarding the transparency of the film of the present invention, when a film having a thickness of 50 μm is measured according to JIS K7105, the total haze value is preferably 30% or less, more preferably 20% or less, and 15% or less. More preferably, it is most preferably 10% or less. Further, 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 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. .

  In the tensile test of the film of the present invention in a 23 ° C. environment, 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 elastic modulus (E '))
The film of the present invention has a measurement temperature of −150 ° C. to 150 ° C. under the conditions of a vibration frequency of 10 Hz, a strain of 0.1%, a heating rate of 2 ° C./minute, and a chuck spacing of 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 film, adjustment is possible by adjusting the rigidity and resin 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.

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

(Natural shrinkage)
The natural shrinkage rate of the film of the present invention is preferably as small as possible. Generally, the natural shrinkage rate 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.
<Molded products, heat-shrinkable labels, containers>

  The film of the present invention can be processed from a flat shape to a cylindrical shape or the like according to 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 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 film of the present invention is excellent in heat shrink characteristics, shrink finish, transparency and the like 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.

  Further, particularly when the film of the present invention is used as a heat-shrinkable label for food containers (for example, PET bottles, glass bottles, preferably PET bottles for soft drinks or foods), a cylindrical shape with a complicated shape (for example, a constricted center) , Square prisms, pentagonal columns, hexagonal columns, etc.) can be adhered to the shape, and a container with a beautiful label without wrinkles or avatars can be obtained. The molded article and container of this invention can be produced by using a normal molding method.

  In addition, since the film of the present invention has excellent low temperature shrinkage and shrink finish, in addition to heat-shrinkable label materials for plastic molded products that are deformed when heated to high temperatures, 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 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.

  The film of the present invention, a label, and a container equipped with the label will be described below with reference to examples.

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

<Measurement method>
(1) Storage elastic modulus (E ')
The polyolefin resin or soft acrylic resin used in the present invention is compressed in a hot press heated at a set temperature of 180 ° C. to 230 ° C. for 3 minutes under a load of 20 MPa, and then immersed in cold water to form a sheet. The obtained film was accurately cut into a size of 4 mm wide × 60 mm long to prepare a sample. Using a viscoelastic spectrometer DVA-200 (manufactured by IT Measurement Co., Ltd.), the measurement temperature is −150 under the conditions of vibration frequency 10 Hz, strain 0.1%, heating rate 2 ° C./min, and chuck 2.5 cm. The dynamic viscoelasticity was measured in the longitudinal direction in the range of from ° C to 150 ° C. The storage elastic modulus (E ′) at 20 ° C. and 70 ° C. is shown in Tables 1 to 3 as the storage elastic modulus (E ′).

  In addition, the storage elastic modulus (E ′) of a mixture of two or more kinds of polyolefin resins is charged into a twin screw extruder (manufactured by Mitsubishi Heavy Industries) with a mixed resin mixed at a predetermined mixing ratio at a set temperature of 180 ° C. It was melt-mixed and pelletized.

(2) 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 80 ° C. for 10 seconds, and the 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.

(3) 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 the results of evaluation are shown in Tables 1 to 3.
◎: 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

(4) Haze value In order to evaluate the transparency of the obtained film, the haze value was measured according to JIS K7105 and evaluated according to the following criteria. The haze value was measured for all haze and internal haze of the film.
◎: When the internal haze value is 10% or less and the total haze value is 15% or less ○: The internal haze value exceeds 10% and 20% or less, and / or the total haze value exceeds 15% and 30% or less X: When the internal haze value exceeds 20% and / or the total haze value exceeds 30%

(5) Appearance The appearance (transparency / surface shape) of the obtained film was evaluated according to the following criteria.
A: Excellent in transparency and surface shape.
○: A slight defect occurs in either the transparency or the surface shape, but this is not a problem in practice.
X: There is a problem in transparency and surface shape, and the appearance is poor.

(6) Shrinkage Finishing A film printed with a grid of 10 mm intervals was cut into a size of MD 170 mm × TD 114 mm, and both ends of TD were overlapped by 10 mm and adhered with a tetrohydrofuran (THF) solvent to produce a cylindrical film. The cylindrical film is attached to a cylindrical plastic bottle with a capacity of 500 mL and is passed through the shrinking tunnel having a length of 3.2 m (3 zones) of the steam heating method for about 4 seconds without rotating. Coated. The atmospheric temperature in the tunnel in each zone was set to a range of 70 to 90 ° C. by adjusting the amount of steam with a steam valve.

After film coating, the following criteria were evaluated.
A: Shrinkage is sufficient and no wrinkles, avatars, whitening, or lattice distortions occur. O: Shrinkage is sufficient, but wrinkles, avatars, whitening, and lattice distortions occur only slightly, but there is no practical problem. : Insufficient shrinkage, or wrinkles, avatars, and lattice distortion

Moreover, the raw material used by each Example and the comparative example is as follows.
(Polylactic acid resin)
-Polylactic acid-based resin: manufactured by Nature Works LLC, trade name: NatureWorks 4050, L-form / D-form weight = 95/5, hereinafter abbreviated as “NW4050”.
-Polylactic acid-based resin: manufactured by Nature Works LLC, trade name: NatureWorks 4060, L-form / D-form weight = 88/12, hereinafter abbreviated as “NW4060”.
-Polylactic acid-based resin: manufactured by Nature Works LLC, trade name: NatureWorks 4042D, L-form / D-form weight = 95.75 / 4.25), hereinafter abbreviated as "NW4042".
-Copolymer of polylactic acid resin, diol and dicarboxylic acid: manufactured by Dainippon Ink & Chemicals, Inc., trade name “Plamate PD150”, hereinafter abbreviated as “PD150”.

(Polyolefin resin)
-Sumitomo Chemical Co., Ltd., trade name: Tough selenium 3512 [Tough selenium raw material X1102 (85% by weight) / random polypropylene (15% by weight), 10 Hz storage elastic modulus: 3 MPa (20 ° C.), 2 MPa (70 ° C.), Tough selenium raw material Is a propylene-butene copolymer], hereinafter abbreviated as “T3512”.
-Dow Chemical Co., Ltd., trade name: Versify 2300, polypropylene-ethylene random copolymer [polypropylene / ethylene = 88/12, 10 Hz storage elastic modulus: 45 Mpa (20 ° C.), 8 Mpa (70 ° C.)], hereinafter “V2300” Abbreviated.
Polyolefin resin: manufactured by Nippon Polyethylene Co., Ltd., trade name: kernel KS240T, specific gravity 0.880, ethylene-propylene-hexene 1 copolymer (= 77/8/15), hereinafter abbreviated as “KS240T”.
Polyolefin-based resin: manufactured by Mitsui DuPont, trade name: EVAFLEX EV270, ethylene-vinyl acetate copolymer (= 72/28), hereinafter abbreviated as “EV270”.
・ Nippon Yushi Co., Ltd., 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 “A5200”.
-Dow Chemical Co., Ltd., trade 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 “V2400” Abbreviated.

[Other resins]
(General-purpose polypropylene resin)
Polyolefin resin: manufactured by Nippon Polypropylene, trade name: Novatec FY6H, polypropylene polymer, hereinafter abbreviated as “FY6H”.

(General-purpose polyethylene resin)
Polyethylene resin: manufactured by Nippon Polyethylene Co., Ltd., trade name: Kernel KF271, polyethylene polymer, hereinafter abbreviated as “KF271”.

(Aliphatic polyester)
Aliphatic polyester: Mitsubishi Chemical Corporation trade name: GS-Pla AZ 91T (polybutylene succinate), hereinafter abbreviated as “GS-Pla”.

(Soft resin other than soft polypropylene)
Silicone acrylic composite rubber, manufactured by Mitsubishi Rayon Co., Ltd., trade name: Methbrene S2001, core-shell structure acrylic-silicone copolymer, hereinafter abbreviated as “S2001”.

(Acrylic resin)
Acrylic resin: manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumipex LG21, specific gravity 1.19, methacrylic resin, hereinafter abbreviated as “LG21”.
Acrylic resin: manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumipex HT50Y, specific gravity 1.17, methacrylic resin, hereinafter abbreviated as “HT50Y”.

(Examples 1-4 , 6-10 , Comparative Examples 1-5 , Reference Example 5 )
Table 1 or polylactic acid resin and a mixed resin obtained by mixing a polyolefin resin shown in Table 3 as the first layer (monolayer) were charged into a biaxial extruder (manufactured by Mitsubishi Heavy Industries, Ltd.), After melt mixing at a set temperature of 200 ° C. and extruding from a die at a set temperature of 200 ° C., it was taken up by a cast roll at 50 ° C. and cooled and solidified to obtain an unstretched sheet having a width of 200 mm and a thickness of 250 μm. Next, the film was stretched in the transverse direction under the conditions of Table 1 or Table 3 with a film tenter (manufactured by Kyoto Kikai Co., Ltd.) to obtain a heat-shrinkable film.

(Examples 11 to 27)
In addition to the first layer, the laminated films (Examples 11 to 27) having the polylactic acid resin as the second layer, the mixed resin constituting the first layer is put into a twin screw extruder (Mitsubishi Heavy Industries, Ltd.), The melted and mixed pellets at a set temperature of 210 ° C. and the mixed resin constituting the second layer were introduced into two single-screw extruders (manufactured by Mitsubishi Heavy Industries, Ltd.). After melt-mixing, each layer has a thickness of 2 layers / first layer / second layer = 30 μm / 190 μm / 30 μm. Thus, an unstretched laminated sheet having a width of 200 mm and a thickness of 250 μm was obtained. Next, this film was stretched in the transverse direction under the conditions of Table 1 or Table 2 using a film tenter (manufactured by Kyoto Kikai Co., Ltd.) to obtain a heat-shrinkable film. The evaluation results of the obtained film are shown in Table 1 or Table 2.

  As shown in Table 1 or Table 2, the films of the present invention (Examples 1 to 27) were excellent in heat shrink characteristics, impact resistance, transparency, and shrink finish. On the other hand, as shown in Table 3, the films (Comparative Examples 1 and 2) in which the mass ratio of the polylactic acid resin and the polyolefin resin exceeds the range defined by the present invention have transparency due to poor dispersion. Remarkably lowered, causing appearance defects. In addition, films having a storage elastic modulus at 20 ° C. exceeding 100 MPa defined by the present invention (Comparative Examples 3 and 4) have a low tensile breaking elongation (longitudinal direction) and poor impact resistance, and have a high haze value and transparency. In addition, voids were observed and the appearance was inferior. Similarly, a film having a storage elastic modulus at 20 ° C. exceeding 100 MPa defined by the present invention (Comparative Example 5) is excellent in tensile elongation at break (longitudinal direction), but has a high haze value and inferior transparency, and further cloudiness. Was recognized and the appearance was inferior.

  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, the present invention can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification, and heat-shrinkable films accompanying such changes are also included in the technical scope of the present invention. It must be understood as a thing.

It is sectional drawing which shows schematically the aspect of the layer structure of the heat-shrinkable film of this invention. It is sectional drawing which shows schematically the other aspect of the layer structure of the heat-shrinkable film of this invention.

Explanation of symbols

(I) Layer made of the mixed resin of the present invention (II) Layer having a resin composition or additive different from that of the mixed resin of the present invention (III) Layer made of mixed resin of the present invention is a resin composition or additive Different layers of

Claims (6)

Containing polylactic acid resin and polyolefin resin as main components,
It consists of a mixed resin in which the mass ratio of this polylactic acid resin and polyolefin resin is 95/5 to 50/50, or has at least one mixed resin layer,
The polylactic acid-based resin is composed of a copolymer of D-lactic acid and L-lactic acid, or a mixed resin of this copolymer, and the D / L ratio of D-lactic acid and L-lactic acid is 3 / 97-15. / 85, or 85/15 to 97/3,
The polyolefin resin is
Oscillation frequency 10 Hz, storage elastic modulus of 20 ° C. as measured under the conditions of strain 0.1% (E ') is 100MPa or less der Rutotomoni, the content of polyethylene component is 70 mass% or more, density of 0. 800-0.910 g / cm ³ polyethylene-based resin, or
A soft polypropylene resin having a storage elastic modulus (E ′) at 20 ° C. of 100 MPa or less when measured under conditions of a vibration frequency of 10 Hz and a strain of 0.1%.
And
A heat-shrinkable film having a heat shrinkage ratio of 20% or more in the main shrinkage direction when stretched in at least one direction and immersed in warm water at 80 ° C. for 10 seconds. The heat-shrinkable film according to claim 1 , wherein a polypropylene component of the soft polypropylene resin is 80% by mass or more. The heat-shrinkable film according to claim 1 or 2 , wherein a tensile breaking elongation in a direction perpendicular to the main shrinkage direction when measured at an atmospheric temperature of 0 ° C and a tensile speed of 100 mm / min is 100% or more. Molded article using as a substrate a heat-shrinkable film according to any one of claims 1-3. The heat-shrinkable label which used the heat-shrinkable film in any one of Claims 1-3 as a base material. A container equipped with the molded article according to claim 4 or the heat-shrinkable label according to claim 5 .

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