WO2020256090A1 - Resin composition for heat-shrinkable film and heat-shrinkable film using same - Google Patents

Resin composition for heat-shrinkable film and heat-shrinkable film using same Download PDF

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Publication number
WO2020256090A1
WO2020256090A1 PCT/JP2020/024067 JP2020024067W WO2020256090A1 WO 2020256090 A1 WO2020256090 A1 WO 2020256090A1 JP 2020024067 W JP2020024067 W JP 2020024067W WO 2020256090 A1 WO2020256090 A1 WO 2020256090A1
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Prior art keywords
heat
shrinkable film
film
resin composition
weight
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PCT/JP2020/024067
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French (fr)
Japanese (ja)
Inventor
朋弥 中村
誠 大西
祐輔 笠木
松田　博行
Original Assignee
大倉工業株式会社
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Priority to CN202080044281.4A priority Critical patent/CN113993949A/en
Priority to JP2021526895A priority patent/JPWO2020256090A1/ja
Publication of WO2020256090A1 publication Critical patent/WO2020256090A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C08L101/16—Compositions of unspecified macromolecular compounds the macromolecular compounds being biodegradable
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/412—Transparent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/54—Yield strength; Tensile strength
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/716—Degradable
    • B32B2307/7163—Biodegradable
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2467/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2467/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones

Definitions

  • the present invention relates to a heat-shrinkable film used for shrink wrapping and the like, which has biodegradability.
  • shrink wrapping in which the object to be packaged is roughly wrapped with a heat-shrinkable film and then passed through a shrink tunnel to shrink the film along the object to be packaged.
  • Most of the heat-shrinkable films used for shrink packaging are made by forming a film of highly chemically stable resin such as polypropylene resin, polyethylene resin, polyvinyl chloride resin, and polystyrene resin, and then the film. Is manufactured by stretching. A heat-shrinkable film made of such a stable resin is hardly decomposed naturally, and if it is improperly dumped, it causes soil pollution and marine pollution.
  • Patent Document 1 has both outer layers composed of polylactic acid (A) having a composition ratio of L-lactic acid and D-lactic acid of 94: 6 to 79:21, and mainly contains an aliphatic polyhydric alcohol and an aliphatic dicarboxylic acid. Alternatively, it has at least one layer composed of an aliphatic polyester (B) synthesized from the derivative thereof or a mixture (C) of the polylactic acid (A) and the aliphatic polyester (B), and the polylactic acid (A) in all layers.
  • polylactic acid (A) having a composition ratio of L-lactic acid and D-lactic acid of 94: 6 to 79:21
  • an aliphatic polyhydric alcohol and an aliphatic dicarboxylic acid Alternatively, it has at least one layer composed of an aliphatic polyester (B) synthesized from the derivative thereof or a mixture (C) of the polylactic acid (A) and the aliphatic polyester (B), and the polylactic acid (A) in all layers.
  • the heat-shrinkable film has a problem that the stretchable temperature range is narrow.
  • Both outer layers shown in Table 3 below are composed of polylactic acid
  • the intermediate layer is composed of a mixture of polylactic acid and polybutylene succinate adipate (resin composition o), and a film having a thickness ratio of 1: 6: 1 (Structure 8).
  • Patent Document 2 includes at least one layer containing a resin composition containing a polylactic acid-based polymer and an aliphatic polyester resin A having a melting point of 100 ° C. to 170 ° C. and a glass transition temperature of 0 ° C. or lower as a main component.
  • the present invention relates to a heat-shrinkable film, which is characterized by having and being a film stretched in at least one axis.
  • a heat-shrinkable film in which both outer layers are made of polylactic acid and the intermediate layer is mainly composed of polylactic acid and polybutylene succinate is disclosed, but the temperature range in which the film can also be stretched. There was a problem that it was narrow.
  • the heat-shrinkable film has a high tensile elastic modulus and is extremely hard, when shrink-wrapped, the corners of the package (both edges of the fusing seal) stand like dog ears, or A phenomenon called "dog year” occurs. If the shrink wrapping has cornering, the tip of the corner may damage other shrink wrapping. Also, if your fingers hit the corners, you may feel "painful".
  • Patent Document 3 describes both outer layers mainly composed of a polylactic acid polymer (A) and at least one inner layer mainly composed of a mixture of polybutylene succinate (B) and polybutylene succinate-adipate copolymer (C).
  • the weight ratio of the polylactic acid-based polymer (A) to the polybutylene succinate (B) and the polybutylene succinate-adipate copolymer (C) in all layers [(A): ((B) + (C) ))] Is disclosed as a heat-shrinkable film having a value of 30:70 to 10:90.
  • the film also has a problem that the temperature range that can be stretched is narrow. Further, the film has a problem that the degree of biomass is low because the compounding ratio of the polylactic acid-based polymer in the whole is 30% by weight or less.
  • plastic films for packaging are required to have a high degree of biomass as well as biodegradability.
  • the degree of biomass is the dry weight ratio of the biomass raw material (plant-derived raw material) in the film.
  • plant-derived raw material plant-derived raw material
  • plastic film When plastic film is incinerated or decomposed by microorganisms, it emits carbon dioxide, which is a greenhouse gas, and it is feared that it may accelerate the progress of global warming.
  • a resin composition for a heat-shrinkable film containing polylactic acid, polybutylene succinate, and polybutylene succinate adipate as main components, and each resin.
  • Polylactic acid: the polybutylene succinate: the polybutylene succinate adipate 5-45% by weight: 5-45% by weight: 50 to 90% by weight, preferably the polylactic acid: the polybutylene succi.
  • Nate: A resin composition for a heat-shrinkable film is provided, wherein the polybutylene succinate adipate 10 to 25% by weight: 5 to 40% by weight: 50 to 70% by weight.
  • the polylactic acid is composed of a biomass raw material
  • the polybutylene succinate is a copolymer of succinic acid derived from biomass and 1,4-butanediol
  • the polybutylene succinate adipate is a succinic acid derived from biomass.
  • the resin composition for a heat-shrinkable film which is a copolymer of an acid, 1,4-butanediol, and succinic acid.
  • a heat-shrinkable film comprising a layer containing the resin composition as a main component.
  • a heat-shrinkable film including an outer layer, an intermediate layer, and an outer layer in this order, wherein the intermediate layer contains the resin composition as a main component, and the outer layers all contain 90% by weight or more of polylactic acid.
  • the heat shrinkable film is provided, characterized in that it is: 7: 1.
  • the resin composition for a heat-shrinkable film of the present invention has biodegradability, it does not easily pollute the global environment. Further, the heat-shrinkable film using the resin composition has flexibility and heat-shrinkability equal to or higher than that of the conventional polypropylene-based heat-shrinkable film. Further, since the stretchable temperature range is wide, a good heat-shrinkable film can be obtained even if the film temperature changes slightly during the stretching treatment. Further, simultaneous biaxial stretching exceeding 4 times in both the vertical direction and the horizontal direction is possible, and a heat-shrinkable film having a high shrinkage rate can be obtained.
  • the degree of biomass in the heat-shrinkable film can be increased. Furthermore, the transparency of the obtained film can be enhanced by providing both outer layers made of a resin composition containing 90% by weight or more of polylactic acid. Furthermore, by setting the thickness ratio of the outer layer and the intermediate layer within a specific range, a heat-shrinkable film having good stretchability, transparency, biomass degree and the like can be obtained.
  • the resin composition for a heat-shrinkable film of the present invention comprises polylactic acid (hereinafter, abbreviated as "PLA” if necessary), polybutylene succinate (hereinafter, abbreviated as “PBS” if necessary), and poly.
  • the main component is butylene succinate adipate (hereinafter, abbreviated as "PBSA” if necessary).
  • PLA Polylactic acid
  • PLA is obtained by producing lactic acid by fermenting starch contained in, for example, corn or potato, and polymerizing this.
  • PLA a resin made of 100% biomass raw material has already been put on the market, and by using the resin, a heat-shrinkable film having a high degree of biomass can be obtained.
  • the PLA may be copolymerized with another hydroxycarboxylic acid as long as the properties of the resin are not impaired, or may contain a small amount of chain extender residue.
  • Other hydroxycarboxylic acid units include optical isomers of lactic acid (D-lactic acid for L-lactic acid, L-lactic acid for D-lactic acid), glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid.
  • 2-Hydroxy-n-butyric acid 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid and other bifunctional aliphatic hydroxycarboxylic acids, and Examples thereof include lactones such as caprolactone, butyrolactone and valerolactone.
  • lactones such as caprolactone, butyrolactone and valerolactone.
  • Such other hydroxycarboxylic acid units are preferably used in less than 15 mol% in PLA.
  • PBS Polybutylene succinate
  • a general bio-PBS has a biomass content of less than 50% by weight.
  • PBS which consists of bio-derived 1,4-butanediol and bio-derived succinic acid, has a biomass content close to 100%. ..
  • the biomass degree of the heat-shrinkable film obtained by using the PBS is further increased.
  • PBSA Polybutylene succinate adipate
  • Bio-PBSA bio-derived succinic acid
  • PBSA has the highest blending ratio in the resin composition of the present invention.
  • the stretchable temperature range can be expanded to the low temperature side.
  • the compounding ratio of PBSA is preferably 60 to 90% by weight, particularly preferably 70 to 90% by weight.
  • bio-PBSA has a lower biomass content than PLA and bio-PBS. Therefore, when it is necessary to increase the biomass degree of the heat-shrinkable film, it is desirable to reduce the amount of bioPBSA used.
  • the blending ratio of bioPBSA should be 50 to 80% by weight, particularly 50 to 70% by weight. Is desirable.
  • the resin composition of the present invention contains 5 to 45% by weight of PLA and PBS, respectively.
  • Both PLA and PBS can extend the stretchable temperature range to the high temperature side.
  • the stretchable temperature range is only on the low temperature side.
  • the compounding ratio of PLA exceeds 45% by weight, the obtained film becomes hard, and there is a possibility that the problem of cornering may occur.
  • the compounding ratio of PBS exceeds 45% by weight, it becomes difficult to stretch the film.
  • the stretchable temperature range is limited to the high temperature side.
  • PLA: PBS: PBSA 10 to 25% by weight: 5 to 40% by weight: 50 to 70% by weight.
  • the heat-shrinkable film of the present invention can be obtained by forming the above-mentioned resin composition into a film and stretching it uniaxially or biaxially.
  • the film when the film is formed by the inflation film forming method, it can be produced by increasing the blow-up ratio and stretching the film.
  • the tubular film formed by the inflation film forming method can be produced by stretching it by the tubular stretching method. It is also possible to produce a film formed by the T-die film forming method by stretching it by a roll stretching method or a tenter stretching method.
  • a conventionally known method can be adopted as the method for producing the heat-shrinkable film of the present invention.
  • the thickness of the heat-shrinkable film of the present invention is preferably 5 to 100 ⁇ m, preferably 10 to 50 ⁇ m, and particularly preferably 12 to 30 ⁇ m.
  • the heat-shrinkable film of the present invention may be a single-layer film composed of only layers containing the above-mentioned resin composition as a main component, but the film is not very transparent. Therefore, it is desirable to use the above-mentioned resin composition as an intermediate layer and provide an outer layer composed of a resin composition containing 90% by weight or more of PLA. Specifically, it is desirable that the film is a multilayer film having an outer layer, an intermediate layer, and an outer layer in this order.
  • the thickness ratio of the outer layer: the intermediate layer: the outer layer is preferably 1: 2: 1 to 1: 10: 1, and particularly preferably 1: 2: 1 to 1: 9: 1 from the viewpoint of stretchability.
  • the thickness ratio of the intermediate layer is high, and the thickness ratio of each layer is preferably 1: 4: 1 to 1: 10: 1. Further, in order to increase the biomass degree of the film, it is desirable to thicken the outer layer having a high proportion of PLA, and the thickness ratio is preferably 1: 2: 1 to 1: 7: 1. Further, considering the flexibility and the degree of biomass of the heat-shrinkable film, the thickness ratio of each layer is 1: 4: 1 to 1: 7: 1, especially 1: 4: 1 to 1: 6.9: 1. desirable.
  • the heat-shrinkable film of the present invention may have another resin layer between the outer layer and the intermediate layer.
  • the adhesive strength between the outer layer and the intermediate layer can be increased.
  • the above-mentioned resin composition for heat-shrinkable film and resin composition for outer layer include biodegradable resins such as polycaprolactone-based resin and polyhydroxybutyrate, as long as the object of the present invention is not impaired.
  • a non-biodegradable resin of 5, 5% by weight or less, and various additives such as a lubricant, a plasticizer, an antiblocking agent, an antifogging agent, an antioxidant, a filler, and a colorant can be blended.
  • PLA2 Polylactic acid REVODE101 manufactured by Kaiseisha (100% biomass)
  • the resin composition shown in Table 1 is formed into a film having a thickness of 240 ⁇ m by the T-die film forming method, and this is simultaneously biaxially stretched four times in the vertical direction and four times in the horizontal direction by a table biaxial stretching machine. .. By the stretching treatment, the film becomes 16 times the original area and the thickness of the film becomes 15 ⁇ m.
  • the film temperature at the time of biaxial stretching is changed to 75 ° C., 80 ° C., 85 ° C., and 90 ° C., and the appearance of the obtained heat-shrinkable film is visually confirmed.
  • the heat-shrinkable film When the heat-shrinkable film is stretched at a low temperature (about 75 to 90 ° C.), the heat-shrinkable film tends to shrink at a low temperature. Therefore, when the object to be packaged is easily deteriorated by heat, it is desirable to shrink-wrap it using a heat-shrinkable film stretched at a low temperature. Those in which the film was broken and could not be stretched to a predetermined magnification, those in which local distortion was observed in the film after the stretching treatment, and those in which the resin was melted and could not be stretched were ⁇ , after the stretching treatment. Table 1 shows ⁇ when the film appearance was good.
  • the resin composition (resin composition a) of the present invention could be stretched at three temperatures of 75 ° C, 80 ° C and 85 ° C. Therefore, even if the film temperature changes slightly during the stretching process, the film is less likely to be distorted. Further, since the stretching treatment can be performed at a low temperature of 75 to 85 ° C., the obtained heat-shrinkable film becomes a film having high shrinkage at a low temperature. Further, the resin composition e and the resin composition f containing 80% by weight or more of bioPBSA had only one temperature at which the stretching treatment could be performed. Further, the resin composition h containing 50% by weight or more of bio-PBS also had only one temperature at which the stretching treatment could be performed. Further, the resin composition i and the resin composition j containing 80% by weight or more of bio-PBS could not be stretched at any temperature.
  • Example 1 A single-layer film having a thickness of 240 ⁇ m was produced from the resin composition a by the T-die film forming method, and then the film was subjected to a biaxial stretching apparatus (Iwamoto Seisakusho Co., Ltd.) at a film temperature of 85 ° C. A heat-shrinkable film of about 15 ⁇ m was obtained by performing simultaneous biaxial stretching treatment 4 times in the vertical direction and 4 times in the horizontal direction.
  • a biaxial stretching apparatus Iwamoto Seisakusho Co., Ltd.
  • Comparative Example 4 (resin composition e) and Comparative Example 5 (resin composition f) were stretched at a film temperature of 75 ° C. Further, Comparative Example 7 (resin composition h) and Comparative Example 8 (resin composition k) were stretched at a film temperature of 90 ° C.
  • the obtained heat-shrinkable film is evaluated by the following method.
  • ⁇ Tensile modulus> Compliant with ASTM D882.
  • the tensile elastic modulus is less than 1500 MPa.
  • ⁇ Haze> Compliant with JIS K 7136.
  • the haze is preferably 15% or less, preferably 10% or less, and more preferably 5% or less.
  • the heat-shrinkable film of Example 1 has three stretchable temperatures and has good stretchability. Further, since the tensile elastic modulus is 1500 MPa or less, a package having a good feel can be obtained, and since the haze is 15% or less, a film having excellent transparency can be obtained.
  • the heat-shrinkable films of Comparative Examples 1 and 2 and Comparative Examples 6 to 7 have a high tensile elastic modulus, and it is difficult to obtain a shrink wrapping body having a good feel. Further, the heat-shrinkable films of Comparative Examples 3, 4, 5, and 8 have a low tensile elastic modulus (1500 MPa or less), but the heat-shrinkable film of Comparative Example 3 has a high haze and is inferior in transparency.
  • the heat-shrinkable films of Comparative Examples 4, 5 and 8 have one stretchable temperature, and there is a concern that the film may break even if the film temperature at the time of stretching changes slightly. Further, since the heat-shrinkable films of Comparative Examples 7 and 8 cannot be stretched at a low temperature, it is necessary to set the temperature of the shrink tunnel high when shrink-wrapping.
  • the stretchable temperature range of the multilayer heat-shrinkable films of configurations 1 to 11 shown in Table 3 is confirmed.
  • a 240 ⁇ m multilayer film is produced by the T-die film forming method.
  • the 240 ⁇ m multilayer film is simultaneously biaxially stretched 4.5 times in the vertical direction and 4.5 times in the horizontal direction with a biaxial stretching device to produce a heat-shrinkable film.
  • the film becomes 20.25 times the original area, and the thickness of the film becomes about 12 ⁇ m.
  • the temperature of the film during biaxial stretching is changed to 75 ° C., 80 ° C., 85 ° C., 90 ° C., and 95 ° C., and the appearance of the obtained heat-shrinkable film is visually confirmed.
  • Example 2 A 240 ⁇ m multilayer film (Structure 4) having the resin composition m as an intermediate layer and having outer layers made of 100% by weight of PLA on both sides of the intermediate layer is produced by a T-die film forming method.
  • the thickness ratio of outer layer: intermediate layer: outer layer is 1: 6: 1.
  • the multilayer film is simultaneously biaxially stretched at a film temperature of 85 ° C. by a biaxial stretching apparatus (Iwamoto Seisakusho Co., Ltd.) 4.5 times in the vertical direction and 4.5 times in the horizontal direction.
  • Table 4 shows the haze, heat shrinkage, and tensile elastic modulus of the obtained heat-shrinkable film.
  • Example 3 A heat-shrinkable film is obtained in the same manner as in Example 2 except that the outer layer is 90% by weight of PLA and 10% by weight of bioPBSA (Structure 7).
  • Table 4 shows the haze, heat shrinkage, and tensile elastic modulus of the obtained heat-shrinkable film.
  • Examples 4 to 8 A heat-shrinkable film is obtained in the same manner as in Example 2 except that the resin composition and the thickness ratio of the intermediate layer are shown in Table 3.
  • Table 4 shows the haze, heat shrinkage, and tensile elastic modulus of the obtained heat-shrinkable film.
  • Heat shrinkage rate ((length before immersion-length after immersion) / length before immersion) ⁇ 100 in the flow direction of the film (MD direction) and the width direction (TD direction) of the film perpendicular to the flow direction. It will be described together with 4.
  • the heat shrinkage rate of a heat shrinkable film made of a general polypropylene resin soaked in a 100 ° C. oil bath for 5 seconds is about 15%.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
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  • Laminated Bodies (AREA)

Abstract

[Problem] The present invention addresses the problem of providing a resin composition for a heat-shrinkable film which is biodegradable and has a wide temperature range in which a stretching treatment can be performed. [Solution] According to the present invention, provided is a resin composition for a heat-shrinkable film, the resin composition being characterized by containing, as main components, a polylactic acid, a polybutylene succinate, and a polybutylene succinate adipate, wherein the blending ratio of each resin is polylactic acid:polybutylene succinate:polybutylene succinate adipate=5-45% by weight:5-45% by weight:50-90% by weight.

Description

熱収縮性フィルム用樹脂組成物およびそれを用いた熱収縮性フィルムResin composition for heat-shrinkable film and heat-shrinkable film using it
　本発明は、シュリンク包装等に用いられる熱収縮性フィルムであって、生分解性を有する熱収縮性フィルムに関する。 The present invention relates to a heat-shrinkable film used for shrink wrapping and the like, which has biodegradability.
　被包装物を熱収縮性フィルムでラフに包んだ後、シュリンクトンネルに通してフィルムを被包装物に沿うように収縮させるシュリンク包装が知られている。シュリンク包装に用いられる熱収縮性フィルムの多くは、ポリプロピレン系樹脂、ポリエチレン系樹脂、ポリ塩化ビニル系樹脂、ポリスチレン系樹脂等の化学的安定性が高い樹脂をフィルム状に製膜した後、該フィルムを延伸処理して製造されている。このような安定な樹脂からなる熱収縮性フィルムは自然に分解されることがほとんどなく、不適切に投棄されると土壌汚染や海洋汚染の原因となる。 There is known shrink wrapping in which the object to be packaged is roughly wrapped with a heat-shrinkable film and then passed through a shrink tunnel to shrink the film along the object to be packaged. Most of the heat-shrinkable films used for shrink packaging are made by forming a film of highly chemically stable resin such as polypropylene resin, polyethylene resin, polyvinyl chloride resin, and polystyrene resin, and then the film. Is manufactured by stretching. A heat-shrinkable film made of such a stable resin is hardly decomposed naturally, and if it is improperly dumped, it causes soil pollution and marine pollution.
　このような問題に鑑み、生分解性樹脂を用いた熱収縮性フィルムが提案されている。
　特許文献１には、Ｌ－乳酸とＤ－乳酸の組成比が９４：６～７９：２１であるポリ乳酸（Ａ）からなる両外層を有し、主として脂肪族多価アルコールと脂肪族ジカルボン酸またはその誘導体から合成された脂肪族ポリエステル（Ｂ）、あるいは上記ポリ乳酸（Ａ）と脂肪族ポリエステル（Ｂ）の混合物（Ｃ）、からなる層を少なくとも一層有し、全層におけるポリ乳酸（Ａ）と脂肪族ポリエステル（Ｂ）の割合が、（Ａ）：（Ｂ）＝３０：７０重量％～７５：２５重量％である多層フィルムを、少なくとも一方向に延伸することによって得られる熱収縮性フィルムが開示されている。該特許文献１の実施例では、脂肪族ポリエステル（Ｂ）としてポリブチレンサクシネートアジペートを用いると、延伸温度９０℃において、縦方向、横方向ともに４倍程度の同時二軸延伸が可能であることが開示されている。 In view of these problems, a heat-shrinkable film using a biodegradable resin has been proposed.
Patent Document 1 has both outer layers composed of polylactic acid (A) having a composition ratio of L-lactic acid and D-lactic acid of 94: 6 to 79:21, and mainly contains an aliphatic polyhydric alcohol and an aliphatic dicarboxylic acid. Alternatively, it has at least one layer composed of an aliphatic polyester (B) synthesized from the derivative thereof or a mixture (C) of the polylactic acid (A) and the aliphatic polyester (B), and the polylactic acid (A) in all layers. ) And the aliphatic polyester (B) in an amount of (A): (B) = 30: 70% by weight to 75: 25% by weight, and the heat shrinkage obtained by stretching the multilayer film in at least one direction. The film is disclosed. In the example of Patent Document 1, when polybutylene succinate adipate is used as the aliphatic polyester (B), simultaneous biaxial stretching of about 4 times in both the vertical direction and the horizontal direction is possible at a stretching temperature of 90 ° C. Is disclosed.
　しかしながら該熱収縮性フィルムは、延伸可能な温度範囲が狭いという問題があった。下記表３に記す両外層がポリ乳酸からなり、中間層がポリ乳酸とポリブチレンサクシネートアジペートの混合物（樹脂組成物ｏ）からなり、厚さ割合が１：６：１のフィルム（構成８）は、全層におけるポリ乳酸とポリブチレンサクシネートアジペートの重量割合が４０：６０であり、概ね特許文献１の実施例３と同等のフィルムである。該フィルムを延伸温度７５℃、８０℃、８５℃、９０℃、９５℃にて、縦方向、横方向ともに４．５倍延伸（フィルム面積が２０．２５倍になるように延伸）したところ、８０℃、８５℃では延伸処理することができたが、そのほかの温度では延伸処理することができなかった。 However, the heat-shrinkable film has a problem that the stretchable temperature range is narrow. Both outer layers shown in Table 3 below are composed of polylactic acid, the intermediate layer is composed of a mixture of polylactic acid and polybutylene succinate adipate (resin composition o), and a film having a thickness ratio of 1: 6: 1 (Structure 8). Is a film in which the weight ratio of polylactic acid and polybutylene succinate adipate in all layers is 40:60, which is substantially the same as in Example 3 of Patent Document 1. When the film was stretched 4.5 times in both the vertical and horizontal directions at stretching temperatures of 75 ° C., 80 ° C., 85 ° C., 90 ° C., and 95 ° C. (stretched so that the film area became 20.25 times). The stretching treatment was possible at 80 ° C. and 85 ° C., but the stretching treatment could not be performed at other temperatures.
　特許文献２は、ポリ乳酸系重合体と、融点が１００℃～１７０℃であり、ガラス転移温度が０℃以下である脂肪族ポリエステル樹脂Ａとの樹脂組成物を主成分とする層を少なくとも一層有し、かつ、少なくとも１軸に延伸したフィルムであることを特徴とする熱収縮性フィルムに関する発明である。特許文献２の実施例では、両外層がポリ乳酸からなり、中間層がポリ乳酸とポリブチレンサクシネートを主成分とする熱収縮性フィルムが開示されているが、当該フィルムも延伸処理できる温度範囲が狭いという問題があった。また該熱収縮性フィルムは引張弾性率が高く、非常に固いため、シュリンク包装すると包装体の角部分（溶断シールの両エッジ部分）が犬の耳のように立つ「角（つの）立ち」または「ドッグイヤー」と呼ばれる現象が発生する。シュリンク包装体に角立ちが発生すると、角の先端部分でほかのシュリンク包装体を傷つける恐れがある。また手指が角の部分に当たると、「痛い」と感じることがある。 Patent Document 2 includes at least one layer containing a resin composition containing a polylactic acid-based polymer and an aliphatic polyester resin A having a melting point of 100 ° C. to 170 ° C. and a glass transition temperature of 0 ° C. or lower as a main component. The present invention relates to a heat-shrinkable film, which is characterized by having and being a film stretched in at least one axis. In the examples of Patent Document 2, a heat-shrinkable film in which both outer layers are made of polylactic acid and the intermediate layer is mainly composed of polylactic acid and polybutylene succinate is disclosed, but the temperature range in which the film can also be stretched. There was a problem that it was narrow. In addition, since the heat-shrinkable film has a high tensile elastic modulus and is extremely hard, when shrink-wrapped, the corners of the package (both edges of the fusing seal) stand like dog ears, or A phenomenon called "dog year" occurs. If the shrink wrapping has cornering, the tip of the corner may damage other shrink wrapping. Also, if your fingers hit the corners, you may feel "painful".
　特許文献３には、ポリ乳酸系ポリマー（Ａ）を主とする両外層と、ポリブチレンサクシネート（Ｂ）及びポリブチレンサクシネート・アジペートコポリマー（Ｃ）の混合物を主とする少なくとも一層の内部層とを有し、全層におけるポリ乳酸系ポリマー（Ａ）とポリブチレンサクシネート（Ｂ）及びポリブチレンサクシネート・アジペートコポリマー（Ｃ）との重量比［（Ａ）：（（Ｂ）＋（Ｃ））］が３０：７０～１０：９０である熱収縮性フィルムが開示されている。該フィルムもまた、延伸処理できる温度範囲が狭いという問題があった。また、該フィルムは、全体におけるポリ乳酸系ポリマーの配合割合が３０重量％以下である為、バイオマス度が低いという問題があった。 Patent Document 3 describes both outer layers mainly composed of a polylactic acid polymer (A) and at least one inner layer mainly composed of a mixture of polybutylene succinate (B) and polybutylene succinate-adipate copolymer (C). The weight ratio of the polylactic acid-based polymer (A) to the polybutylene succinate (B) and the polybutylene succinate-adipate copolymer (C) in all layers [(A): ((B) + (C) ))] Is disclosed as a heat-shrinkable film having a value of 30:70 to 10:90. The film also has a problem that the temperature range that can be stretched is narrow. Further, the film has a problem that the degree of biomass is low because the compounding ratio of the polylactic acid-based polymer in the whole is 30% by weight or less.
　近年、包装用のプラスチックフィルムには、生分解性だけでなく、高いバイオマス度も求められている。バイオマス度とは、フィルムにおけるバイオマス原料（植物由来原料）の乾燥重量割合である。プラスチックフィルムは、焼却処分や微生物により分解される際に、温室効果ガスである二酸化炭素を排出する為、地球温暖化の進行を早めるのではないかと危惧されている。しかしながらバイオマス原料を用いると、原料が製造される過程（＝植物が生育する過程）で二酸化炭素が吸収されるため、地球温暖化に与える影響が低減する。 In recent years, plastic films for packaging are required to have a high degree of biomass as well as biodegradability. The degree of biomass is the dry weight ratio of the biomass raw material (plant-derived raw material) in the film. When plastic film is incinerated or decomposed by microorganisms, it emits carbon dioxide, which is a greenhouse gas, and it is feared that it may accelerate the progress of global warming. However, when a biomass raw material is used, carbon dioxide is absorbed in the process of manufacturing the raw material (= the process of growing plants), so that the influence on global warming is reduced.
特開２００１－０４７５８３JP 2001-047583 特開２００４－００２７７６JP-A-2004-002776 特開２００７－３２０２９０JP-A-2007-320290
　本発明は、生分解性を有する熱収縮性フィルムにおいて、延伸処理できる温度範囲が広く角立ちの問題のない熱収縮性フィルムを提供することを課題とする。更に、バイオマス度が高く、透明性も良好な熱収縮性フィルムの提供を課題とする。 An object of the present invention is to provide a biodegradable heat-shrinkable film having a wide temperature range that can be stretched and having no problem of angularity. Another object of the present invention is to provide a heat-shrinkable film having a high degree of biomass and good transparency.
　本発明によると上記課題を解決するための手段として、ポリ乳酸と、ポリブチレンサクシネートと、ポリブチレンサクシネートアジペートと、を主成分とする熱収縮性フィルム用樹脂組成物であって、各樹脂の配合割合が、前記ポリ乳酸：前記ポリブチレンサクシネート：前記ポリブチレンサクシネートアジペート＝５～４５重量％：５～４５重量％：５０～９０重量％、好ましくは前記ポリ乳酸：前記ポリブチレンサクシネート：前記ポリブチレンサクシネートアジペート＝１０～２５重量％：５～４０重量％：５０～７０重量％あることを特徴とする熱収縮性フィルム用樹脂組成物が提供される。
　また、前記ポリ乳酸がバイオマス原料からなり、前記ポリブチレンサクシネートが、バイオマス由来のコハク酸と、１，４－ブタンジオールの共重合体であり、前記ポリブチレンサクシネートアジペートが、バイオマス由来のコハク酸と、１，４－ブタンジオールと、アジピン酸の共重合体であることを特徴とする前記熱収縮性フィルム用樹脂組成物が提供される。
　更に、前記樹脂組成物を主成分とする層を備えることを特徴とする熱収縮性フィルムが提供される。
　更にまた、外層、中間層、外層を順に備える熱収縮性フィルムであって、前記中間層が前記樹脂組成物を主成分とし、前記外層が、いずれもポリ乳酸を９０重量％以上含む樹脂組成物からなることを特徴とする熱収縮性フィルムが提供される。
　更にまた、前記外層と前記中間層の厚さ割合が、外層：中間層：外層＝１：２：１～１：１０：１、さらには外層：中間層：外層＝１：４：１～１：７：１であることを特徴とする前記熱収縮性フィルムが提供される。 According to the present invention, as a means for solving the above problems, a resin composition for a heat-shrinkable film containing polylactic acid, polybutylene succinate, and polybutylene succinate adipate as main components, and each resin. Polylactic acid: the polybutylene succinate: the polybutylene succinate adipate = 5-45% by weight: 5-45% by weight: 50 to 90% by weight, preferably the polylactic acid: the polybutylene succi. Nate: A resin composition for a heat-shrinkable film is provided, wherein the polybutylene succinate adipate = 10 to 25% by weight: 5 to 40% by weight: 50 to 70% by weight.
Further, the polylactic acid is composed of a biomass raw material, the polybutylene succinate is a copolymer of succinic acid derived from biomass and 1,4-butanediol, and the polybutylene succinate adipate is a succinic acid derived from biomass. Provided is the resin composition for a heat-shrinkable film, which is a copolymer of an acid, 1,4-butanediol, and succinic acid.
Further, there is provided a heat-shrinkable film comprising a layer containing the resin composition as a main component.
Furthermore, a heat-shrinkable film including an outer layer, an intermediate layer, and an outer layer in this order, wherein the intermediate layer contains the resin composition as a main component, and the outer layers all contain 90% by weight or more of polylactic acid. Provided is a heat shrinkable film comprising:
Furthermore, the thickness ratio of the outer layer to the intermediate layer is such that outer layer: intermediate layer: outer layer = 1: 2: 1 to 1:10: 1, and further outer layer: intermediate layer: outer layer = 1: 4: 1 to 1. The heat shrinkable film is provided, characterized in that it is: 7: 1.
　本発明の熱収縮性フィルム用樹脂組成物は生分解性を備えるため、地球環境を汚染しにくい。また該樹脂組成物を用いた熱収縮性フィルムは、従来のポリプロピレン系の熱収縮フィルムと同等、あるいはそれ以上の柔軟性や熱収縮性を備える。また延伸可能な温度範囲が広いため、延伸処理時にフィルム温度が多少変化しても、良好な熱収縮性フィルムを得ることができる。さらに縦方向、横方向共に４倍を超える同時二軸延伸も可能であり、収縮率の高い熱収縮性フィルムを得ることができる。
　更に、ポリブチレンサクシネートやポリブチレンサクシネートアジペートとして、バイオマス由来のコハク酸を共重合させた樹脂を採用することにより、熱収縮性フィルムにおけるバイオマス度を高めることができる。
　更にまた、ポリ乳酸を９０重量％以上含む樹脂組成物からなる両外層を設けることにより得られるフィルムの透明性を高めることができる。
　更にまた、外層と中間層の厚さ割合を特定範囲内とすることにより、延伸性、透明性、バイオマス度等の良好な熱収縮性フィルムを得ることができる。 Since the resin composition for a heat-shrinkable film of the present invention has biodegradability, it does not easily pollute the global environment. Further, the heat-shrinkable film using the resin composition has flexibility and heat-shrinkability equal to or higher than that of the conventional polypropylene-based heat-shrinkable film. Further, since the stretchable temperature range is wide, a good heat-shrinkable film can be obtained even if the film temperature changes slightly during the stretching treatment. Further, simultaneous biaxial stretching exceeding 4 times in both the vertical direction and the horizontal direction is possible, and a heat-shrinkable film having a high shrinkage rate can be obtained.
Further, by adopting a resin obtained by copolymerizing succinic acid derived from biomass as polybutylene succinate or polybutylene succinate adipate, the degree of biomass in the heat-shrinkable film can be increased.
Furthermore, the transparency of the obtained film can be enhanced by providing both outer layers made of a resin composition containing 90% by weight or more of polylactic acid.
Furthermore, by setting the thickness ratio of the outer layer and the intermediate layer within a specific range, a heat-shrinkable film having good stretchability, transparency, biomass degree and the like can be obtained.
　以下、本発明を詳細に説明するが、本発明は以下に限定されるものではなく、同様の効果を奏する範囲において種々の実施形態をとることができる。 Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following, and various embodiments can be taken as long as the same effect is obtained.
［熱収縮性フィルム用樹脂組成物］
　本発明の熱収縮性フィルム用樹脂組成物は、ポリ乳酸（以下、必要に応じ「ＰＬＡ」と略称する）と、ポリブチレンサクシネート（以下、必要に応じ「ＰＢＳ」と略称する）と、ポリブチレンサクシネートアジペート（以下、必要に応じ「ＰＢＳＡ」と略称する）と、を主成分とする。 [Resin composition for heat shrinkable film]
The resin composition for a heat-shrinkable film of the present invention comprises polylactic acid (hereinafter, abbreviated as "PLA" if necessary), polybutylene succinate (hereinafter, abbreviated as "PBS" if necessary), and poly. The main component is butylene succinate adipate (hereinafter, abbreviated as "PBSA" if necessary).
＜ポリ乳酸（ＰＬＡ）＞
　ＰＬＡは、例えばトウモロコシやジャガイモ等に含まれるでんぷんを発酵することにより乳酸を製造し、これを重合することにより得られる。ＰＬＡは１００％バイオマス原料からなる樹脂がすでに上市されており、該樹脂を用いることでバイオマス度の高い熱収縮性フィルムを得ることができる。
　尚、ＰＬＡは、樹脂の性質を損なわない範囲で、他のヒドロキシカルボン酸を共重合してもよく、また少量の鎖延長剤残基を含んでいてもよい。他のヒドロキシカルボン酸単位としては、乳酸の光学異性体（Ｌ－乳酸に対してはＤ－乳酸、Ｄ－乳酸に対してはＬ－乳酸）、グリコール酸、３－ヒドロキシ酪酸、４－ヒドロキシ酪酸、２－ヒドロキシ－ｎ－酪酸、２－ヒドロキシ－３，３－ジメチル酪酸、２－ヒドロキシ－３－メチル酪酸、２－メチル乳酸、２－ヒドロキシカプロン酸等の２官能脂肪族ヒドロキシカルボン酸類、およびカプロラクトン、ブチロラクトン、バレロラクトン等のラクトン類が挙げられる。このような他のヒドロキシカルボン酸単位は、ＰＬＡ中１５モル％未満で使用するのがよい。 <Polylactic acid (PLA)>
PLA is obtained by producing lactic acid by fermenting starch contained in, for example, corn or potato, and polymerizing this. As for PLA, a resin made of 100% biomass raw material has already been put on the market, and by using the resin, a heat-shrinkable film having a high degree of biomass can be obtained.
The PLA may be copolymerized with another hydroxycarboxylic acid as long as the properties of the resin are not impaired, or may contain a small amount of chain extender residue. Other hydroxycarboxylic acid units include optical isomers of lactic acid (D-lactic acid for L-lactic acid, L-lactic acid for D-lactic acid), glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid. , 2-Hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid and other bifunctional aliphatic hydroxycarboxylic acids, and Examples thereof include lactones such as caprolactone, butyrolactone and valerolactone. Such other hydroxycarboxylic acid units are preferably used in less than 15 mol% in PLA.
＜ポリブチレンサクシネート（ＰＢＳ）＞
　ＰＢＳは、１，４－ブタンジオールとコハク酸の縮合反応により得られる脂肪族ポリエステルで、該脂肪族ポリエステルをポリイソシアネート等により高分子量化したものを含む。
　近年、トウモロコシを発酵させるなどしてバイオ由来のコハク酸を製造し、これを１，４－ブタンジオールと重合させたもの（以下、必要に応じ「バイオＰＢＳ」と略称する）が上市されている。このような樹脂を採用することにより、熱収縮性フィルムのバイオマス度を高めることができる。一般的なバイオＰＢＳは、バイオマス度が５０重量％弱である。
　また、バイオ由来の１，４－ブタンジオールの開発も進んでおり、バイオ由来の１，４－ブタンジオールとバイオ由来のコハク酸からなるバイオマス度が１００％に近いＰＢＳの上市が期待されている。当該ＰＢＳを用いると得られる熱収縮性フィルムのバイオマス度はさらに高くなる。 <Polybutylene succinate (PBS)>
PBS is an aliphatic polyester obtained by a condensation reaction of 1,4-butanediol and succinic acid, and includes an aliphatic polyester obtained by increasing the molecular weight of the aliphatic polyester with polyisocyanate or the like.
In recent years, bio-derived succinic acid produced by fermenting corn and polymerized with 1,4-butanediol (hereinafter abbreviated as "bio-PBS" as necessary) has been put on the market. .. By adopting such a resin, the biomass degree of the heat-shrinkable film can be increased. A general bio-PBS has a biomass content of less than 50% by weight.
In addition, the development of bio-derived 1,4-butanediol is progressing, and it is expected that PBS, which consists of bio-derived 1,4-butanediol and bio-derived succinic acid, has a biomass content close to 100%. .. The biomass degree of the heat-shrinkable film obtained by using the PBS is further increased.
＜ポリブチレンサクシネートアジペート（ＰＢＳＡ）＞
　ＰＢＳＡは、１，４－ブタンジオールとコハク酸とアジピン酸から得られる脂肪族ポリエステルで、ポリイソシアネート等により高分子量化したものを含む。
　ＰＢＳと同様に、バイオ由来のコハク酸を使用したもの（以下、必要に応じ「バイオＰＢＳＡ」と略称する）が上市されている。該バイオＰＢＳＡを採用することにより、熱収縮性フィルムのバイオマス度を高めることができる。一般的なバイオＰＢＳＡのバイオマス度は３３重量％前後である。また、バイオ由来の１，４－ブタンジオールとバイオ由来のコハク酸を用いたＰＢＳＡの上市が期待されているが、このようなＰＢＳＡを用いると得られる熱収縮性フィルムのバイオマス度はさらに高くなる。 <Polybutylene succinate adipate (PBSA)>
PBSA is an aliphatic polyester obtained from 1,4-butanediol, succinic acid and adipic acid, and contains a high molecular weight polyester such as polyisocyanate.
Similar to PBS, those using bio-derived succinic acid (hereinafter, abbreviated as "Bio-PBSA" as necessary) are on the market. By adopting the bio-PBSA, the biomass degree of the heat-shrinkable film can be increased. The biomass degree of general bio-PBSA is around 33% by weight. Further, it is expected that PBSA using bio-derived 1,4-butanediol and bio-derived succinic acid will be put on the market, but the biomass degree of the heat-shrinkable film obtained by using such PBSA will be further increased. ..
＜配合割合＞
　本発明の樹脂組成物における各樹脂の配合割合は、ＰＬＡ：ＰＢＳ：ＰＢＳＡ＝５～４５重量％：５～４５重量％：５０～９０重量％である。本発明の樹脂組成物において最も配合割合が高いのはＰＢＳＡである。ＰＢＳＡを５０重量％以上配合することにより、延伸可能な温度範囲を低温側に広げることができる。尚、ＰＢＳＡの配合割合が多くなるほど、得られる熱収縮性フィルムの引張弾性率は低くなり、上述した「角立ち」の発生を抑えることができる。このような状況に鑑みるとＰＢＳＡの配合割合は６０～９０重量％が好ましく、特に７０～９０重量％が好ましい。
　またバイオＰＢＳＡは、ＰＬＡやバイオＰＢＳと比較すると、バイオマス度が低い。よって熱収縮性フィルムのバイオマス度を高める必要がある場合は、バイオＰＢＳＡの使用量を抑えることが望ましい。熱収縮性フィルムの破断強度を向上させ、延伸可能な温度範囲を狭めることなく、バイオマス度を高めるためには、バイオＰＢＳＡの配合割合が５０～８０重量％、特に５０～７０重量％であることが望ましい。 <Mixing ratio>
The blending ratio of each resin in the resin composition of the present invention is PLA: PBS: PBSA = 5 to 45% by weight: 5 to 45% by weight: 50 to 90% by weight. PBSA has the highest blending ratio in the resin composition of the present invention. By blending PBSA in an amount of 50% by weight or more, the stretchable temperature range can be expanded to the low temperature side. As the blending ratio of PBSA increases, the tensile elastic modulus of the obtained heat-shrinkable film decreases, and the occurrence of the above-mentioned "square standing" can be suppressed. In view of such a situation, the compounding ratio of PBSA is preferably 60 to 90% by weight, particularly preferably 70 to 90% by weight.
In addition, bio-PBSA has a lower biomass content than PLA and bio-PBS. Therefore, when it is necessary to increase the biomass degree of the heat-shrinkable film, it is desirable to reduce the amount of bioPBSA used. In order to improve the breaking strength of the heat-shrinkable film and increase the degree of biomass without narrowing the stretchable temperature range, the blending ratio of bioPBSA should be 50 to 80% by weight, particularly 50 to 70% by weight. Is desirable.
　また本発明の樹脂組成物には、ＰＬＡ、ＰＢＳがそれぞれ５～４５重量％配合される。ＰＬＡ、ＰＢＳはいずれも延伸可能な温度範囲を高温側に広げることができる。ＰＬＡ、もしくはＰＢＳの配合割合が５重量％未満の場合は、延伸可能な温度範囲が低温側のみになる。また、ＰＬＡの配合割合が４５重量％を超えると得られるフィルムが固くなり、角立ちの問題が発生する恐れがある。またＰＢＳの配合割合が４５重量％を超えると、フィルムを延伸することが困難となる。またＰＬＡの配合割合とＰＢＳの配合割合の和が５０重量％を超えると、延伸可能な温度範囲が高温側のみになる。また熱収縮性フィルムの柔軟性の付与とバイオマス度等を考慮すると、ＰＬＡ：ＰＢＳ：ＰＢＳＡ＝１０～２５重量％：５～４０重量％：５０～７０重量％であることが望ましい。 Further, the resin composition of the present invention contains 5 to 45% by weight of PLA and PBS, respectively. Both PLA and PBS can extend the stretchable temperature range to the high temperature side. When the blending ratio of PLA or PBS is less than 5% by weight, the stretchable temperature range is only on the low temperature side. Further, if the compounding ratio of PLA exceeds 45% by weight, the obtained film becomes hard, and there is a possibility that the problem of cornering may occur. Further, if the compounding ratio of PBS exceeds 45% by weight, it becomes difficult to stretch the film. Further, when the sum of the blending ratio of PLA and the blending ratio of PBS exceeds 50% by weight, the stretchable temperature range is limited to the high temperature side. Further, in consideration of imparting flexibility of the heat-shrinkable film and the degree of biomass, it is desirable that PLA: PBS: PBSA = 10 to 25% by weight: 5 to 40% by weight: 50 to 70% by weight.
＜熱収縮性フィルム＞
　本発明の熱収縮性フィルムは、上述した樹脂組成物を、フィルム状に製膜し、これを一軸延伸、あるいは二軸延伸することにより得ることができる。例えば、インフレーション製膜法により製膜する際に、ブローアップ比を大きくして、延伸処理することにより製造することもできる。更にインフレーション製膜法により製膜されたチューブ状のフィルムを、チューブラー延伸法により延伸して製造することもできる。またＴダイ製膜法により製膜されたフィルムをロール延伸法やテンター延伸法により延伸して製造することもできる。尚、本発明の熱収縮性フィルムの製造方法は、その他、従来公知の方法を採用することができる。
　本発明の熱収縮性フィルムの厚さは、５～１００μｍであることが望ましく、１０～５０μｍ、特に１２～３０μｍであることが望ましい。 <Heat shrinkable film>
The heat-shrinkable film of the present invention can be obtained by forming the above-mentioned resin composition into a film and stretching it uniaxially or biaxially. For example, when the film is formed by the inflation film forming method, it can be produced by increasing the blow-up ratio and stretching the film. Further, the tubular film formed by the inflation film forming method can be produced by stretching it by the tubular stretching method. It is also possible to produce a film formed by the T-die film forming method by stretching it by a roll stretching method or a tenter stretching method. In addition, as the method for producing the heat-shrinkable film of the present invention, a conventionally known method can be adopted.
The thickness of the heat-shrinkable film of the present invention is preferably 5 to 100 μm, preferably 10 to 50 μm, and particularly preferably 12 to 30 μm.
＜多層フィルム＞
　本発明の熱収縮性フィルムは、上述した樹脂組成物を主成分とする層のみからなる単層のフィルムであってもよいが、該フィルムは透明性があまり高くない。そこで上述した樹脂組成物を中間層とし、ＰＬＡを９０重量％以上含む樹脂組成物からなる外層を設けることが望ましい。具体的には、外層、中間層、外層を順に備える多層フィルムであることが望ましい。
　外層：中間層：外層の厚さ割合は１：２：１～１：１０：１であることが望ましく、特に１：２：１～１：９：１が延伸性の面から好ましい。フィルムの柔軟性を考慮すると中間層の厚さ割合が高いことが望ましく、各層の厚さ割合は１：４：１～１：１０：１が望ましい。またフィルムのバイオマス度を高めるためには、ＰＬＡの配合割合が高い外層を厚くすることが望ましく、厚さ割合は１：２：１～１：７：１が望ましい。さらに、熱収縮性フィルムの柔軟性及びバイオマス度を考慮すると、各層の厚さ割合は１：４：１～１：７：１、特に、１：４：１～１：６．９：１が望ましい。 <Multilayer film>
The heat-shrinkable film of the present invention may be a single-layer film composed of only layers containing the above-mentioned resin composition as a main component, but the film is not very transparent. Therefore, it is desirable to use the above-mentioned resin composition as an intermediate layer and provide an outer layer composed of a resin composition containing 90% by weight or more of PLA. Specifically, it is desirable that the film is a multilayer film having an outer layer, an intermediate layer, and an outer layer in this order.
The thickness ratio of the outer layer: the intermediate layer: the outer layer is preferably 1: 2: 1 to 1: 10: 1, and particularly preferably 1: 2: 1 to 1: 9: 1 from the viewpoint of stretchability. Considering the flexibility of the film, it is desirable that the thickness ratio of the intermediate layer is high, and the thickness ratio of each layer is preferably 1: 4: 1 to 1: 10: 1. Further, in order to increase the biomass degree of the film, it is desirable to thicken the outer layer having a high proportion of PLA, and the thickness ratio is preferably 1: 2: 1 to 1: 7: 1. Further, considering the flexibility and the degree of biomass of the heat-shrinkable film, the thickness ratio of each layer is 1: 4: 1 to 1: 7: 1, especially 1: 4: 1 to 1: 6.9: 1. desirable.
　また本発明の熱収縮性フィルムは、外層と中間層の間に他の樹脂層を有していてもよい。外層と中間層の間に、例えば接着層を設けることにより、外層と中間層の接着強度を高めることができる。該接着層には、外層を成す樹脂組成物と中間層を成す樹脂組成物の混合物を採用することが望ましく、例えば本発明の熱収縮性フィルムを製造する過程で生じるエッジトリム（耳ロス）を再生して使用すると、資源の有効利用にもつながる。 Further, the heat-shrinkable film of the present invention may have another resin layer between the outer layer and the intermediate layer. By providing, for example, an adhesive layer between the outer layer and the intermediate layer, the adhesive strength between the outer layer and the intermediate layer can be increased. It is desirable to use a mixture of the resin composition forming the outer layer and the resin composition forming the intermediate layer for the adhesive layer, for example, edge trim (ear loss) generated in the process of producing the heat-shrinkable film of the present invention. Regeneration and use will lead to effective use of resources.
　尚、上述した熱収縮性フィルム用樹脂組成物や外層用の樹脂組成物には、いずれも本発明の目的を損なわない範囲で、ポリカプロラクトン系樹脂やポリヒドロキシブチレート等の生分解性樹脂や、５重量%以下の非生分解性樹脂、更には滑剤、可塑剤、アンチブロッキング剤、防曇剤、酸化防止剤、充てん剤、着色剤等の各種添加剤を配合することができる。 The above-mentioned resin composition for heat-shrinkable film and resin composition for outer layer include biodegradable resins such as polycaprolactone-based resin and polyhydroxybutyrate, as long as the object of the present invention is not impaired. A non-biodegradable resin of 5, 5% by weight or less, and various additives such as a lubricant, a plasticizer, an antiblocking agent, an antifogging agent, an antioxidant, a filler, and a colorant can be blended.
　以下、実施例、比較例に基づき、本発明の効果を確認する。尚、本発明の実施例、比較例で使用した樹脂は以下のとおりである。
ＰＬＡ１・・・Ｔｏｔａｌ－Ｃｏｒｂｉｏｎ社製のポリ乳酸　ＬｕｍｉｎｙＬＸ１７５（バイオマス度１００％）
ＰＬＡ２・・・海生社製のポリ乳酸　ＲＥＶＯＤＥ１０１（バイオマス度１００％）
バイオＰＢＳ・・・ＰＴＴ　ＭＣＣ　Ｂｉｏｃｈｅｍ社製ポリブチレンサクシネート　ＢｉｏＰＢＳ　ＦＺ９１ＰＭ（バイオマス由来のコハク酸を用いており、バイオマス度４８．５％）
バイオＰＢＳＡ・・・ＰＴＴ　ＭＣＣ　Ｂｉｏｃｈｅｍ社製ポリブチレンサクシネートアジペート　ＢｉｏＰＢＳ　ＦＤ９２ＰＭ（バイオマス由来のコハク酸を用いており、バイオマス度３３．５％） Hereinafter, the effects of the present invention will be confirmed based on Examples and Comparative Examples. The resins used in the examples and comparative examples of the present invention are as follows.
PLA1 ・ ・ ・ Polylactic acid LuminyLX175 manufactured by Total-Corbion (100% biomass)
PLA2: Polylactic acid REVODE101 manufactured by Kaiseisha (100% biomass)
BioPBS ・ ・ ・ PTT MCC Polybutylene succinate manufactured by Biochem BioPBS FZ91PM (using biomass-derived succinic acid, biomass degree 48.5%)
BioPBSA ・ ・ ・ PTT MCC Polybutylene succinate adipate manufactured by Biochem BioPBS FD92PM (using biomass-derived succinic acid, biomass degree 33.5%)
＜延伸可能な温度範囲の確認＞
　表１に示す樹脂組成物をＴダイ製膜法にて厚さ２４０μｍフィルムに製膜し、これをテーブル二軸延伸機にて縦方向に４倍、横方向に４倍、同時二軸延伸する。該延伸処理によりフィルムは元の面積の１６倍となり、フィルムの厚さは１５μｍとなる。二軸延伸する際のフィルム温度を７５℃、８０℃、８５℃、９０℃に変化させ、得られた熱収縮性フィルムの外観を目視確認する。尚、熱収縮性フィルムは低温（７５～９０℃程度）で延伸処理すると、低温で熱収縮しやすくなる。よって被包装物が熱により変質しやすい場合は、低温で延伸処理された熱収縮性フィルムを用いてシュリンク包装することが望まれる。
　フィルムが破断して所定の倍率まで延伸できなかったものや、延伸処理後のフィルムに局所的な歪みが見られたもの、樹脂が溶融して延伸処理できなかったものは×、延伸処理後のフィルム外観が良好であったものは○を表１に記す。 <Confirmation of stretchable temperature range>
The resin composition shown in Table 1 is formed into a film having a thickness of 240 μm by the T-die film forming method, and this is simultaneously biaxially stretched four times in the vertical direction and four times in the horizontal direction by a table biaxial stretching machine. .. By the stretching treatment, the film becomes 16 times the original area and the thickness of the film becomes 15 μm. The film temperature at the time of biaxial stretching is changed to 75 ° C., 80 ° C., 85 ° C., and 90 ° C., and the appearance of the obtained heat-shrinkable film is visually confirmed. When the heat-shrinkable film is stretched at a low temperature (about 75 to 90 ° C.), the heat-shrinkable film tends to shrink at a low temperature. Therefore, when the object to be packaged is easily deteriorated by heat, it is desirable to shrink-wrap it using a heat-shrinkable film stretched at a low temperature.
Those in which the film was broken and could not be stretched to a predetermined magnification, those in which local distortion was observed in the film after the stretching treatment, and those in which the resin was melted and could not be stretched were ×, after the stretching treatment. Table 1 shows ○ when the film appearance was good.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　本発明の樹脂組成物（樹脂組成物ａ）は、７５℃、８０℃、８５℃の３つの温度で延伸処理することができた。よって、延伸処理時にフィルム温度が多少変化しても、フィルムに歪みが発生しにくい。また７５～８５℃という低温で延伸処理することができるため、得られる熱収縮性フィルムが低温での収縮性の高いフィルムとなる。
　またバイオＰＢＳＡが８０重量％以上含まれる樹脂組成物ｅ、樹脂組成物ｆは延伸処理できる温度が１つしかなかった。また、バイオＰＢＳが５０重量％以上含まれる樹脂組成物ｈも延伸処理できる温度が１つしかなかった。更に、バイオＰＢＳが８０重量％以上含まれる樹脂組成物ｉ、樹脂組成物ｊはいずれの温度でも延伸処理できなかった。　 The resin composition (resin composition a) of the present invention could be stretched at three temperatures of 75 ° C, 80 ° C and 85 ° C. Therefore, even if the film temperature changes slightly during the stretching process, the film is less likely to be distorted. Further, since the stretching treatment can be performed at a low temperature of 75 to 85 ° C., the obtained heat-shrinkable film becomes a film having high shrinkage at a low temperature.
Further, the resin composition e and the resin composition f containing 80% by weight or more of bioPBSA had only one temperature at which the stretching treatment could be performed. Further, the resin composition h containing 50% by weight or more of bio-PBS also had only one temperature at which the stretching treatment could be performed. Further, the resin composition i and the resin composition j containing 80% by weight or more of bio-PBS could not be stretched at any temperature.
［実施例１］
Ｔダイ製膜法にて、樹脂組成物ａより厚さ２４０μｍの単層のフィルムを製造し、次いで該フィルムを、二軸延伸装置((株)岩本製作所）にて、フィルム温度８５℃にて、縦方向に４倍、横方向に４倍、同時二軸延伸処理を施し、約１５μｍの熱収縮性フィルムを得た。
［比較例１～８］
　樹脂組成物ｂ～ｈ、および樹脂組成物ｋを用いて、実施例１と同様にして比較例１～比較例８の熱収縮性フィルムを得た。但し、比較例４（樹脂組成物ｅ）、比較例５（樹脂組成物ｆ）はフィルム温度７５℃で延伸処理を行った。また比較例７（樹脂組成物ｈ）、比較例８（樹脂組成物ｋ）はフィルム温度９０℃で延伸処理を行った。 [Example 1]
A single-layer film having a thickness of 240 μm was produced from the resin composition a by the T-die film forming method, and then the film was subjected to a biaxial stretching apparatus (Iwamoto Seisakusho Co., Ltd.) at a film temperature of 85 ° C. A heat-shrinkable film of about 15 μm was obtained by performing simultaneous biaxial stretching treatment 4 times in the vertical direction and 4 times in the horizontal direction.
[Comparative Examples 1 to 8]
Using the resin compositions b to h and the resin composition k, heat-shrinkable films of Comparative Examples 1 to 8 were obtained in the same manner as in Example 1. However, Comparative Example 4 (resin composition e) and Comparative Example 5 (resin composition f) were stretched at a film temperature of 75 ° C. Further, Comparative Example 7 (resin composition h) and Comparative Example 8 (resin composition k) were stretched at a film temperature of 90 ° C.
　得られた熱収縮性フィルムの評価を以下の方法で行う。
＜引張弾性率＞
　ＡＳＴＭ　Ｄ８８２に準拠する。シュリンク包装した後の角立ちの問題を抑えるためには、引張弾性率が１５００ＭＰａを下回ることが望ましい。
＜ヘーズ＞
　ＪＩＳ　Ｋ　７１３６に準拠する。ヘーズは透明性の観点から１５％以下、好ましくは１０％以下、より好ましくは５％以下であることが望ましい。 The obtained heat-shrinkable film is evaluated by the following method.
<Tensile modulus>
Compliant with ASTM D882. In order to suppress the problem of cornering after shrink wrapping, it is desirable that the tensile elastic modulus is less than 1500 MPa.
<Haze>
Compliant with JIS K 7136. From the viewpoint of transparency, the haze is preferably 15% or less, preferably 10% or less, and more preferably 5% or less.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
＜角硬さ＞
　実施例１及び比較例１、３、４、７の熱収縮性フィルムを用いて、小型容器に入った被包装物３つをまとめてシュリンク包装（集積包装）した。得られた包装体の角部分を手で触り、角の硬さを確認した。引張弾性率が非常に高い比較例１、比較例７の熱収縮性フィルムを用いると、角部分が非常に硬く手指を突き刺す感じがあった。引張弾性率が１５００ＭＰａを下回る実施例１及び比較例３、４の熱収縮性フィルムを用いた包装体は、角部分が柔らかく、一般的なポリプロピレンからなる熱収縮性フィルムを用いたものと同様の手触りであった。これらの試験結果より、引張弾性率と角の硬さには相関関係があることが確認できた。尚、フィルムの引張弾性率は１５００ＭＰａ以下であることが好ましい。 <Square hardness>
Using the heat-shrinkable films of Example 1 and Comparative Examples 1, 3, 4, and 7, three objects to be packaged in a small container were shrink-wrapped (accumulated packaging). The corners of the obtained package were touched by hand to confirm the hardness of the corners. When the heat-shrinkable films of Comparative Examples 1 and 7 having a very high tensile elastic modulus were used, the corners were very hard and there was a feeling of piercing the fingers. The packages using the heat-shrinkable films of Examples 1 and Comparative Examples 3 and 4 having a tensile elastic modulus of less than 1500 MPa have soft corners and are similar to those using a heat-shrinkable film made of general polypropylene. It was a touch. From these test results, it was confirmed that there is a correlation between the tensile elastic modulus and the hardness of the angle. The tensile elastic modulus of the film is preferably 1500 MPa or less.
　実施例１の熱収縮性フィルムは延伸可能な温度数が３つあり、延伸性が良好である。また引張弾性率も１５００ＭＰａ以下である為、手触りの良好な包装体を得ることができ、ヘーズも１５％以下である為、透明性に優れたフィルムを得ることができる。
　比較例１～２、比較例６～７の熱収縮性フィルムは、引張弾性率が高く、手触りの良好なシュリンク包装体を得ることは難しい。また比較例３、４、５、８の熱収縮性フィルムは、引張弾性率は低い（１５００ＭＰａ以下である）が、比較例３の熱収縮性フィルムはヘーズが高く透明性に劣るものであり、比較例４、５、８の熱収縮性フィルムは延伸可能な温度数が１つであり、延伸する際のフィルム温度が若干変化するだけで、フィルムが破断する等の懸念がある。更に、比較例７、８の熱収縮性フィルムは、低温において延伸処理することができないため、シュリンク包装する際にシュリンクトンネルの温度を高く設定する必要がある。 The heat-shrinkable film of Example 1 has three stretchable temperatures and has good stretchability. Further, since the tensile elastic modulus is 1500 MPa or less, a package having a good feel can be obtained, and since the haze is 15% or less, a film having excellent transparency can be obtained.
The heat-shrinkable films of Comparative Examples 1 and 2 and Comparative Examples 6 to 7 have a high tensile elastic modulus, and it is difficult to obtain a shrink wrapping body having a good feel. Further, the heat-shrinkable films of Comparative Examples 3, 4, 5, and 8 have a low tensile elastic modulus (1500 MPa or less), but the heat-shrinkable film of Comparative Example 3 has a high haze and is inferior in transparency. The heat-shrinkable films of Comparative Examples 4, 5 and 8 have one stretchable temperature, and there is a concern that the film may break even if the film temperature at the time of stretching changes slightly. Further, since the heat-shrinkable films of Comparative Examples 7 and 8 cannot be stretched at a low temperature, it is necessary to set the temperature of the shrink tunnel high when shrink-wrapping.
＜延伸可能な温度範囲の確認＞
　次に、表３に示す構成１～１１の多層の熱収縮性フィルムについて、延伸可能な温度範囲を確認する。
　初めにＴダイ製膜法にて２４０μｍの多層フィルムを製造する。次いで、該２４０μｍの多層フィルムを、二軸延伸装置にて、縦方向に４．５倍、横方向に４．５倍、同時二軸延伸して熱収縮性フィルムを製造する。該延伸処理によりフィルムは元の面積の２０．２５倍となり、フィルムの厚さは約１２μｍ程度となる。二軸延伸する際のフィルムの温度を７５℃、８０℃、８５℃、９０℃、９５℃に変化させ、得られた熱収縮性フィルムの外観を目視確認する。 <Confirmation of stretchable temperature range>
Next, the stretchable temperature range of the multilayer heat-shrinkable films of configurations 1 to 11 shown in Table 3 is confirmed.
First, a 240 μm multilayer film is produced by the T-die film forming method. Next, the 240 μm multilayer film is simultaneously biaxially stretched 4.5 times in the vertical direction and 4.5 times in the horizontal direction with a biaxial stretching device to produce a heat-shrinkable film. By the stretching treatment, the film becomes 20.25 times the original area, and the thickness of the film becomes about 12 μm. The temperature of the film during biaxial stretching is changed to 75 ° C., 80 ° C., 85 ° C., 90 ° C., and 95 ° C., and the appearance of the obtained heat-shrinkable film is visually confirmed.
　フィルムが破断して所定の倍率まで延伸できなかったものや、延伸処理後のフィルムに局所的な歪みが見られたもの、樹脂が溶融して延伸できなかったものは×、延伸処理後のフィルム外観が良好であったものは○を表３に記す。 If the film broke and could not be stretched to a predetermined magnification, if the film after stretching treatment had local distortion, or if the resin melted and could not be stretched, x, the film after stretching treatment Table 3 shows circles for those with a good appearance.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表１と表３とを比較すると、両外層にＰＬＡを設けることによって、延伸可能な温度範囲が、若干高温側にシフトするものの、高倍率（縦横共に４．５倍）の同時二軸延伸ができること、延伸可能な温度範囲が広がることが確認できた。また、構成２～５の結果より、本発明の樹脂組成物を中間層として用いると、厚さ割合が変化しても、延伸可能な温度範囲が非常に広いことが確認できた。 Comparing Table 1 and Table 3, by providing PLA on both outer layers, the temperature range that can be stretched shifts to the high temperature side, but simultaneous biaxial stretching at high magnification (4.5 times both vertically and horizontally) is possible. It was confirmed that it was possible and that the stretchable temperature range was widened. Further, from the results of the configurations 2 to 5, it was confirmed that when the resin composition of the present invention was used as the intermediate layer, the stretchable temperature range was very wide even if the thickness ratio changed.
［実施例２］
　樹脂組成物ｍを中間層とし、該中間層の両側にＰＬＡ１００重量％からなる外層を有する２４０μｍ多層フィルム(構成４)を、Ｔダイ製膜法にて製造する。尚、外層：中間層：外層の厚さ割合は、１：６：１である。次いで、該多層フィルムを、フィルム温度８５℃にて、二軸延伸装置((株)岩本製作所）で縦方向に４．５倍、横方向に４．５倍、同時二軸延伸する。得られた熱収縮性フィルムのヘーズ、熱収縮率、引張弾性率を表４に記す。 [Example 2]
A 240 μm multilayer film (Structure 4) having the resin composition m as an intermediate layer and having outer layers made of 100% by weight of PLA on both sides of the intermediate layer is produced by a T-die film forming method. The thickness ratio of outer layer: intermediate layer: outer layer is 1: 6: 1. Next, the multilayer film is simultaneously biaxially stretched at a film temperature of 85 ° C. by a biaxial stretching apparatus (Iwamoto Seisakusho Co., Ltd.) 4.5 times in the vertical direction and 4.5 times in the horizontal direction. Table 4 shows the haze, heat shrinkage, and tensile elastic modulus of the obtained heat-shrinkable film.
［実施例３］
　外層をＰＬＡ９０重量％とバイオＰＢＳＡ１０重量％とする（構成７）以外は、実施例２と同様にして熱収縮性フィルムを得る。得られた熱収縮性フィルムのヘーズ、熱収縮率、引張弾性率を表４に記す。
［実施例４～８］
　中間層の樹脂組成物及び厚さ割合を表３に示すものとする以外は実施例２と同様にして熱収縮性フィルムを得る。得られた熱収縮性フィルムのヘーズ、熱収縮率、引張弾性率を表４に記す。
［比較例９、１０］
　樹脂組成物ｏを中間層とした（構成８）以外は、実施例２と同様にして、比較例９の熱収縮性フィルムを得た。また樹脂組成物ｆを中間層とした（構成９）以外は、実施例２と同様にして、比較例１０の熱収縮性フィルムを得た。得られた熱収縮性フィルムのヘーズ、熱収縮率、引張弾性率を表４に記す。 [Example 3]
A heat-shrinkable film is obtained in the same manner as in Example 2 except that the outer layer is 90% by weight of PLA and 10% by weight of bioPBSA (Structure 7). Table 4 shows the haze, heat shrinkage, and tensile elastic modulus of the obtained heat-shrinkable film.
[Examples 4 to 8]
A heat-shrinkable film is obtained in the same manner as in Example 2 except that the resin composition and the thickness ratio of the intermediate layer are shown in Table 3. Table 4 shows the haze, heat shrinkage, and tensile elastic modulus of the obtained heat-shrinkable film.
[Comparative Examples 9 and 10]
A heat-shrinkable film of Comparative Example 9 was obtained in the same manner as in Example 2 except that the resin composition o was used as an intermediate layer (Structure 8). Further, a heat-shrinkable film of Comparative Example 10 was obtained in the same manner as in Example 2 except that the resin composition f was used as an intermediate layer (Structure 9). Table 4 shows the haze, heat shrinkage, and tensile elastic modulus of the obtained heat-shrinkable film.
＜熱収縮率＞
　実施例２～８、比較例９、１０の熱収縮性フィルムを、１００ｍｍ×１００ｍｍの正方形に切り出し、１００℃のオイルバスに５秒間浸漬後、取り出してフィルムの長さを測定した。フィルムの流れ方向（MD方向）及び前記流れ方向に垂直のフィルムの幅方向（TD方向）の熱収縮率（（浸漬前長さ－浸漬後長さ）／浸漬前長さ）×１００）を表４に併せて記す。尚、一般的なポリプロピレン系樹脂からなる熱収縮性フィルムの１００℃オイルバス５秒浸漬の熱収縮率は１５％程度である。 <Heat shrinkage rate>
The heat-shrinkable films of Examples 2 to 8 and Comparative Examples 9 and 10 were cut into squares of 100 mm × 100 mm, immersed in an oil bath at 100 ° C. for 5 seconds, and then taken out to measure the length of the film. Table shows the heat shrinkage rate ((length before immersion-length after immersion) / length before immersion) × 100 in the flow direction of the film (MD direction) and the width direction (TD direction) of the film perpendicular to the flow direction. It will be described together with 4. The heat shrinkage rate of a heat shrinkable film made of a general polypropylene resin soaked in a 100 ° C. oil bath for 5 seconds is about 15%.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表２と表４とを比較すると、両外層にＰＬＡからなる層を設けることで、ポリプロピレン系熱収縮性フィルム(ヘーズ５．０％程度)よりもヘーズが低くなることが確認できた。またＰＬＡ層を設けると、熱収縮性フィルムのバイオマス度が高くなるので、二酸化炭素の排出量を低減することができる。
　また、実施例２～８の熱収縮性フィルムは、１００℃における収縮率がポリプロピレン系の熱収縮性フィルム（収縮率１５％）よりも、大幅に高いことが確認できた。また前記のようにシュリンク包装して角の硬さを確認し、実施例２～８の熱収縮性フィルムは硬くなく手指に突き刺さる感じはなく良好であった。よって複雑な形状をした被包装物であっても、低温で美麗にシュリンク包装することができる。したがって熱により変質しやすい物品をシュリンク包装する用途に適する。 Comparing Table 2 and Table 4, it was confirmed that the haze was lower than that of the polypropylene-based heat-shrinkable film (haze of about 5.0%) by providing the layers made of PLA on both outer layers. Further, when the PLA layer is provided, the degree of biomass of the heat-shrinkable film is increased, so that the amount of carbon dioxide emissions can be reduced.
Further, it was confirmed that the heat-shrinkable films of Examples 2 to 8 had a shrinkage rate at 100 ° C. significantly higher than that of the polypropylene-based heat-shrinkable film (shrinkage rate of 15%). Further, the hardness of the corners was confirmed by shrink wrapping as described above, and the heat-shrinkable films of Examples 2 to 8 were not hard and did not feel like sticking to fingers and were good. Therefore, even an object to be packaged having a complicated shape can be neatly shrink-wrapped at a low temperature. Therefore, it is suitable for shrink wrapping articles that are easily deteriorated by heat.

Claims (7)

  1. ポリ乳酸と、ポリブチレンサクシネートと、ポリブチレンサクシネートアジペートと、を主成分とする熱収縮性フィルム用樹脂組成物であって、
    　各樹脂の配合割合が、前記ポリ乳酸：前記ポリブチレンサクシネート：前記ポリブチレンサクシネートアジペート＝５～４５重量％：５～４５重量％：５０～９０重量％であることを特徴とする熱収縮性フィルム用樹脂組成物。     A resin composition for a heat-shrinkable film containing polylactic acid, polybutylene succinate, and polybutylene succinate adipate as main components.
    The blending ratio of each resin is polylactic acid: polybutylene succinate: polybutylene succinate adipate = 5-45% by weight: 5-45% by weight: 50-90% by weight. Resin composition for sex films.
  2. 前記各樹脂の配合割合が、前記ポリ乳酸：前記ポリブチレンサクシネート：前記ポリブチレンサクシネートアジペート＝１０～２５重量％：５～４０重量％：５０～７０重量％であることを特徴とする請求項１記載の熱収縮性フィルム用樹脂組成物。 The claim is characterized in that the blending ratio of each of the resins is polylactic acid: polybutylene succinate: polybutylene succinate adipate = 10 to 25% by weight: 5 to 40% by weight: 50 to 70% by weight. Item 2. The resin composition for a heat-shrinkable film according to Item 1.
  3. 前記ポリ乳酸がバイオマス原料からなり、
    　前記ポリブチレンサクシネートが、バイオマス由来のコハク酸と、１，４－ブタンジオールの共重合体であり、
    　前記ポリブチレンサクシネートアジペートが、バイオマス由来のコハク酸と、１，４－ブタンジオールと、アジピン酸の共重合体であることを特徴とする請求項１または２記載の熱収縮性フィルム用樹脂組成物。     The polylactic acid is made of biomass raw material
    The polybutylene succinate is a copolymer of biomass-derived succinic acid and 1,4-butanediol.
    The resin composition for a heat-shrinkable film according to claim 1 or 2, wherein the polybutylene succinate adipate is a copolymer of biomass-derived succinic acid, 1,4-butanediol, and adipic acid. Stuff.
  4. 請求項１乃至３のいずれかに記載の樹脂組成物を主成分とする層を備えることを特徴とする熱収縮性フィルム。 A heat-shrinkable film comprising a layer containing the resin composition according to any one of claims 1 to 3 as a main component.
  5. 外層、中間層、外層を順に備える熱収縮性フィルムであって、
    　前記中間層が請求項１乃至３のいずれかに記載の樹脂組成物を主成分とし、
    　前記外層が、いずれもポリ乳酸を９０重量％以上含む樹脂組成物からなることを特徴とする熱収縮性フィルム。     A heat-shrinkable film having an outer layer, an intermediate layer, and an outer layer in this order.
    The intermediate layer contains the resin composition according to any one of claims 1 to 3 as a main component.
    A heat-shrinkable film, wherein the outer layer is made of a resin composition containing 90% by weight or more of polylactic acid.
  6. 前記外層と前記中間層の厚さ割合が、外層：中間層：外層＝１：２：１～１：１０：１であることを特徴とする請求項５記載の熱収縮性フィルム。 The heat-shrinkable film according to claim 5, wherein the thickness ratio of the outer layer to the intermediate layer is outer layer: intermediate layer: outer layer = 1: 2: 1 to 1: 10: 1.
  7. 前記外層と前記中間層の厚さ割合が、外層：中間層：外層＝１：４：１～１：７：１であることを特徴とする請求項５または６記載の熱収縮性フィルム。

          The heat-shrinkable film according to claim 5 or 6, wherein the thickness ratio of the outer layer to the intermediate layer is outer layer: intermediate layer: outer layer = 1: 4: 1 to 1: 7: 1.
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