JP2019038169A - Heat shrinkable laminated film - Google Patents

Abstract

Disclosed is a heat-shrinkable laminated film having excellent oxygen gas barrier properties, shrinkage, and transparency, and excellent adhesion between layers. A (I) layer, (II) layer, and (III) layer composed of the following resin compositions have three layers adjacent in the order of (I) layer / (II) layer / (III) layer. And a heat shrinkable laminated film having a maximum shrinkage stress in the main shrinkage direction of 3.0 MPa or more and 9.5 MPa or less when immersed in a 100 ° C. silicon bath for 1 minute. (I) Layer: Resin composition mainly composed of a thermoplastic resin (II) Layer: Polyamide system in which the ratio of hard segment to soft segment is hard segment / soft segment = 10-60 mass% / 40-90 mass% Resin composition based on elastomer (III) layer: Resin composition based on ethylene vinyl alcohol copolymer [selection figure] None

Description

  The present invention relates to a heat-shrinkable laminated film excellent in gas barrier properties, aroma retention, transparency, interlayer adhesion, heat shrinkability, and delamination suppression during shrinkage. More specifically, food packaging materials, beverage packaging materials, pharmaceutical / medical packaging materials, chemical packaging materials, cosmetics using excellent gas barrier properties, fragrance retention, transparency and excellent shrinkage The present invention relates to a heat-shrinkable laminated film that can be suitably used for packaging materials, packaging materials for toiletries, industrial packaging materials, packaging materials for agricultural materials, and the like.

  Heat-shrinkable films are widely used as packaging materials for foods, beverages, pharmaceuticals, medical products, chemicals, cosmetics, toiletries, industrial parts, agricultural materials, etc., and are required for articles and packaging films that are subject to packaging. The functions are also diversified. For example, in fields such as pharmaceuticals, chemicals, and cosmetics, it has been required to suppress the deterioration of contents due to oxygen or the like.

Generally, films such as polystyrene resins, polyester resins, polylactic acid resins, etc. are used as heat-shrinkable films for containers filled with a liquid material, but these resins are used when oxygen barrier properties are required. Then, it becomes difficult to provide sufficient gas barrier properties.
On the other hand, a multilayer film using an ethylene vinyl alcohol copolymer is known as a packaging material having a high oxygen barrier property. However, when the multilayer film is used as a heat shrinkable film, the ethylene vinyl alcohol copolymer is used. Since the stretchability of the polymer is poor, it has been difficult to obtain a heat-shrinkable film having excellent shrinkage characteristics and suitable shrinkage stress. In the case of a multilayer film using an ethylene vinyl alcohol copolymer, the most important technical problem is to select an adhesive resin layer in order to adhere another thermoplastic resin layer.

  In response to these problems, multilayer shrink films (Patent Documents 1 and 2) using an ethylene vinyl alcohol copolymer containing a structural unit having a 1,2-glycol bond in the side chain are disclosed.

  A base material layer containing a thermoplastic resin having a melting point of 130 ° C. or higher, a gas barrier layer containing a saponified ethylene vinyl alcohol copolymer having an ethylene content of 40 mol% or lower and a melting point of 160 ° C. or lower, and a polyethylene resin. A heat-shrinkable laminated film (Patent Document 3) or ethylene containing an adhesive layer between the base material layer and the gas barrier layer or between the heat seal layer and the gas barrier layer. A heat-shrinkable film having at least one composition layer composed of an ethylene vinyl alcohol copolymer having an amount of 20 to 60 mol%, a saponification degree of 90% or more and an aromatic polyamide resin of 5 to 95% by weight (Patent Document) 4) is disclosed.

  Furthermore, as a laminate, a biaxially stretched heat-shrinkable film containing at least 80% by weight of a polyethylene terephthalate polymer, a solventless adhesive film, a film having a low heat shrinkage rate that is allowed to use ethylene vinyl alcohol, A composite material layer (adhesive resin layer) having a specific tensile modulus and a thermoplastic elastomer layer are sequentially laminated on both sides of a laminate (Patent Document 5) containing a gas and a gas barrier layer made of an ethylene vinyl alcohol copolymer. A laminated body (Patent Document 6) is disclosed.

JP 2006-123531 A JP 2007-261075 A Japanese Patent Laid-Open No. 2006-179648 JP-A-5-77352 JP-T-2004-538189 Japanese Patent Laid-Open No. 9-314763

  In Patent Documents 1 and 2, by using an ethylene vinyl alcohol copolymer containing a specific structural unit in the side chain, an effect is seen with respect to stretchability, heat shrinkability, and delamination resistance during shrinkage. Yes. However, regarding the selection of the most important adhesive layer in the laminated film of different materials, although the description of the assumed layer configuration can be seen, only the modified polyolefin polymer is listed as a suitable adhesive resin. There is no mention of the polyamide-based elastomer described later. In addition, regarding delamination resistance at the time of shrinkage, it is speculated that the cause is due to a decrease in interlayer adhesion after shrinkage, and it has been mentioned that the delamination at the time of shrinkage is closely correlated with the maximum shrinkage stress. Absent.

  Moreover, also in patent document 3, what is suitably used for the contact bonding layer used between a base material layer and a gas barrier layer or a heat seal layer and a gas barrier layer is only a modified polyolefin resin. In addition, it is mentioned that no peak occurs in the shrinkage stress in order to suppress deformation of the package, but the stress value can be controlled by the hard segment / soft segment ratio of the adhesive resin, No mention is made that delami correlates closely with the maximum shrinkage stress. Patent Document 4 also describes that when a multilayer structure is used, an adhesive resin may be interposed between the layers. However, an example is that an unsaturated carboxylic acid or an anhydride thereof is an olefin polymer. Or it is only what was grafted to the copolymer, and the reference regarding the polyamide-type elastomer mentioned later is not seen at all.

  Regarding the laminate disclosed in Patent Document 5, it is described that an elastomer system is used as the solventless adhesive coating, but only examples relating to polyurethane are described.

Furthermore, in patent document 6, in order to join the layer which consists of an ethylene vinyl alcohol copolymer, and a thermoplastic elastomer layer, it has a joining material layer as essential between both layers.
Maleic anhydride-modified polypropylene is used as the bonding material layer. On the other hand, as the thermoplastic elastomer layer, an olefin-based thermoplastic elastomer or a polyamide-based thermoplastic elastomer is used.
However, even when a polyamide-based thermoplastic elastomer is used as the thermoplastic elastomer layer, a joining material layer is interposed, and maleic anhydride-modified polypropylene is used for the joining material layer.
That is, it has not been found that the layer made of an ethylene vinyl alcohol copolymer and the polyamide-based elastomer layer are adjacent to each other so as to have excellent interlayer adhesion.

  The present invention has been made in view of the above problems, and provides a heat-shrinkable laminated film excellent in gas barrier properties, scent retention, shrinkage, transparency, and excellent in adhesion between layers and delamination during shrinkage. It is in.

  As a result of intensive studies, the inventors have succeeded in obtaining a heat-shrinkable laminated film that can solve the above-described problems of the prior art, and have completed the present invention. That is, the object of the present invention is achieved by the following heat-shrinkable laminated film (hereinafter also referred to as “heat-shrinkable laminated film of the present invention”).

That is, the problem of the present invention is that the (I) layer, (II) layer, and (III) layer composed of the following resin composition are adjacent in the order of (I) layer / (II) layer / (III) layer. This is solved by a heat-shrinkable laminated film having three layers and having a maximum shrinkage stress in the main shrinkage direction of 3.0 MPa or more and 9.5 MPa or less when immersed in a 100 ° C. silicon bath for 1 minute.
(I) Layer: Resin composition mainly composed of a thermoplastic resin (II) Layer: Polyamide system in which the ratio of hard segment to soft segment is hard segment / soft segment = 10-60 mass% / 40-90 mass% Resin composition mainly composed of elastomer (III) layer: Resin composition mainly composed of ethylene vinyl alcohol copolymer

  According to the present invention, it is possible to obtain a heat-shrinkable laminated film excellent in gas barrier properties, aroma retention, transparency, shrinkage properties, interlayer adhesion, and delamination suppression during shrinkage. It can be suitably used for packaging foods, drugs, industrial chemicals, etc.

FIG. 1 is a schematic view of a measurement jig that uses delamination during evaluation of the heat-shrinkable laminated film of the present invention for evaluation.

  Hereinafter, the heat-shrinkable laminated film of the present invention as an example of the embodiment of the present invention will be described. However, the scope of the present invention is not limited to the embodiments described below.

  In the present specification, the “main component” means a component that occupies 50% by mass or more when the total of the constituent resin compositions is 100% by mass, preferably 60% by mass or more, and 70% by mass. % Or more is more preferable.

<The heat-shrinkable laminated film of the present invention>
<(I) layer>
The (I) layer in the heat-shrinkable laminated film of the present invention is composed of a resin composition mainly composed of a thermoplastic resin.

Examples of the thermoplastic resin include polyolefin resin, polystyrene resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, chlorinated polyethylene resin, polyester resin, polycarbonate resin, polyamide resin, ethylene Vinyl alcohol copolymer, ethylene vinyl acetate copolymer, polymethylpentene resin, polyvinyl alcohol resin, cyclic olefin resin, polylactic acid resin, polybutylene succinate resin, polyacrylonitrile resin, polyethylene oxide Resin, cellulose resin, polyimide resin, polyurethane resin, polyphenylene sulfide resin, polyphenylene ether resin, polyvinyl acetal resin, polybutadiene resin, polybutene resin, polyamide resin Resin, polyamide bismaleimide resin, polyarylate resin, polyetherimide resin, polyether ether ketone resin, polyether ketone resin, polyether sulfone resin, polyketone resin, polysulfone resin, aramid resin Resins, fluorine resins, polyacetal resins and the like can be mentioned.
Above all, from the viewpoints of transparency, rigidity, coextrusion properties, gas barrier properties, environmental hygiene, odor, interlayer adhesion with (II) layer described later, polystyrene resins, polyolefin resins, cyclic polyolefin resins, polyester systems Resins are preferred, and polyester resins are more preferred.

  When the polyester resin is a copolymer having a dicarboxylic acid component and a polyhydric alcohol component as constituent units, examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, , 3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-methyl-1,5- Alkylene glycol such as pentanediol, 2,2-diethyl-1,3-propanediol, 1,9-nonanediol, 1,10-decanediol, 1,1-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexane Of alicyclic diols such as sandimethanol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, trimethylolpropane, glycerin, pentaerythritol, dimer diol, polyoxytetramethylene glycol, polyethylene glycol, bisphenol compounds or derivatives thereof An alkylene oxide adduct can be used. These may be used alone or in combination of two or more. Of these, ethylene glycol and 1,4-butanediol are preferably used as the main component of the polyhydric alcohol component.

  When the alicyclic diol component is obtained by reacting a dicarboxylic acid compound and a diol compound to obtain a polyester resin, a part of the alicyclic diol compound is mixed in the diol compound to form a single copolymer and The thing which was done is mentioned. In addition, a polyester resin obtained by reacting a dicarboxylic acid compound and an alicyclic diol compound is synthesized and mixed with a polyester resin obtained by reacting a dicarboxylic acid compound and a diol compound such as ethylene glycol other than the alicyclic diol compound. The thing which was done is mentioned.

  When the polyester resin is a copolymer having a dicarboxylic acid component and a polyhydric alcohol component as constituent units, aromatic dicarboxylic acids, ester-forming derivatives thereof, aliphatic dicarboxylic acids, etc. are used as the dicarboxylic acid component. be able to. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalene-1,4- or -2,6 dicarboxylic acid, 5-sodium sulfoisophthalic acid, 1,4-cyclohexanedicarboxylic acid, orthophthalic acid, phenylenedioxy Diacetic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenoxyethanedicarboxylic acid, 4,4′-diphenylether dicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid or an ester-forming derivative thereof. As the aliphatic dicarboxylic acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid, succinic acid, dimer acid, malonic acid or an ester-forming derivative thereof can be used. These may be used alone or in combination of two or more. Among these, terephthalic acid is preferably used as the main component of the dicarboxylic acid component.

  When the aromatic dicarboxylic acid component is reacted with a dicarboxylic acid compound and a diol compound to obtain a polyester resin, a part of the aromatic dicarboxylic acid compound is mixed in the dicarboxylic acid compound to form a single copolymer. Are listed. In addition, a polyester resin obtained by reacting an aromatic dicarboxylic acid compound and a diol compound is synthesized and mixed with a polyester resin obtained by reacting a diol compound and a dicarboxylic acid compound such as terephthalic acid other than the aromatic dicarboxylic acid compound. The thing which was done is mentioned.

The thermoplastic resin as the main component of the layer (I) includes transparency, rigidity, coextrusion, gas barrier properties, environmental hygiene, odor, interlayer adhesion with the layer (II) described later, and heat shrinkage. From the viewpoint of imparting properties, it is preferable to use at least two of a polyethylene terephthalate copolymer (A) and a polybutylene terephthalate copolymer (B).
In imparting heat shrinkability, the heat shrink behavior can be adjusted by using at least two of the copolymer (A) and the copolymer (B). That is, since the glass transition temperature (Tg) of the copolymer (A) and the Tg of the copolymer (B) are greatly different, the heat shrinkage rate of the heat shrinkable laminated film is increased by mixing both. As a result, the rapid shrinkage from the start of thermal shrinkage can be suppressed. In addition, the crystallinity of the two types can be controlled by using at least two types of the copolymer (A) and the copolymer (B). Therefore, inhibition of heat shrinkability due to excessive crystallization can be suppressed, and a sufficient shrinkage rate can be imparted to the heat shrinkable laminated film.

<Polyethylene terephthalate copolymer (A)>
The polyethylene terephthalate copolymer (A) that can be preferably used for the layer (I) contains terephthalic acid as a dicarboxylic acid component. Moreover, what contains isophthalic acid is preferable. Terephthalic acid is preferably contained in a proportion of 80 to 100 mol% in 100 mol% of all dicarboxylic acid components constituting the copolymer (A), more preferably 83 to 97 mol%, still more preferably 86 to 94 mol%. It is. If terephthalic acid is contained in a proportion of 80 to 100 mol% in 100 mol% of all dicarboxylic acid components, high crystallinity can be obtained, so that sufficient strength can be secured for the heat-shrinkable laminated film, which is preferable.

  The polyethylene terephthalate copolymer (A) contains ethylene glycol as a diol component. Moreover, what contains 1, 4- cyclohexane dimethanol and diethylene glycol is preferable. Ethylene glycol is preferably contained in a proportion of 65 to 90 mol% in 100 mol% of all diol components constituting the copolymer (A), more preferably 68 to 87 mol%, still more preferably 71 to 84 mol%. is there. If ethylene glycol is contained in a proportion of 65 to 90 mol% in 100 mol% of all diol components, high crystallinity can be obtained, and thus sufficient strength can be secured in the heat-shrinkable laminated film.

  Further, 1,4-cyclohexanedimethanol contained in the polyethylene terephthalate copolymer (A) is contained in a proportion of 10 to 35 mol% in 100 mol% of all diol components constituting the copolymer (A). More preferably, it is 13-32 mol%, More preferably, it is 16-29 mol%. If 1,4-cyclohexanedimethanol is contained in a proportion of 10 to 35 mol% in 100 mol% of all diol components, the polyethylene terephthalate copolymer can exhibit good impact resistance in the heat-shrinkable laminated film. Since the melting point of (A) can be lowered, coextrudability with the later-described (II) layer and (III) layer can be improved, which is preferable.

  The content of diethylene glycol contained in the polyethylene terephthalate copolymer (A) is preferably less than 12 mol%, more preferably 10 mol%, in 100 mol% of all diol components constituting the copolymer (A). Less than, more preferably less than 8 mol%. By setting the content of diethylene glycol to less than 12 mol%, embrittlement with time of the heat-shrinkable laminated film obtained can be suppressed.

<Polybutylene terephthalate copolymer (B)>
The polybutylene terephthalate copolymer (B) that can be preferably used for the layer (I) contains terephthalic acid as a dicarboxylic acid component. Moreover, what contains isophthalic acid is preferable. The terephthalic acid is preferably contained in a proportion of 80 to 99 mol% in 100 mol% of all dicarboxylic acid components constituting the copolymer (B), more preferably 83 to 96 mol%, still more preferably 86 to 93 mol%. It is. If terephthalic acid is included in the proportion of 80 to 99 mol% of all dicarboxylic acid components, high crystallinity can be obtained, so that sufficient strength can be secured for the heat-shrinkable laminated film.

  The isophthalic acid contained in the polybutylene terephthalate copolymer (B) is preferably contained in a proportion of 1 to 20 mol% in 100 mol% of all dicarboxylic acids constituting the copolymer (B), more preferably. Is 4 to 17 mol%, more preferably 7 to 14 mol%. It is preferable that isophthalic acid is contained in a proportion of 1 to 20 mol% in all dicarboxylic acid components, since crystallinity can be moderately suppressed and good printing and sealing suitability can be obtained in a heat-shrinkable laminated film.

  The polybutylene terephthalate copolymer (B) contains 1,4-butanediol as a diol component.

When the polyethylene terephthalate copolymer (A) and the polybutylene terephthalate copolymer (B) are used in combination in the layer (I), the copolymer (A) and the copolymer (B) When the total mass is 100 mass%, the composition ratio of the copolymer (A) and the copolymer (B) is (A) / (B) = 70 to 95 mass% / 5 to 30 mass%. It is preferable that (A) / (B) = 75 to 90% by mass / 10 to 25% by mass, and (A) / (B) = 80 to 90% by mass / 10 to 20% by mass. More preferably.
When the composition ratio of the copolymer (A) and the copolymer (B) is (A) / (B) = 70 to 95% by mass / 5 to 30% by mass, it is suitable for imparting shrinkage characteristics. It is possible to adjust the glass transition temperature and crystallinity, and it is preferable because a heat-shrinkable laminated film having a high shrinkage ratio and excellent impact resistance and fracture resistance can be obtained. Moreover, even if paying attention to shrinkage characteristics, shrinkage during storage at room temperature can be suppressed by using the above-described composition ratio. Moreover, when it heats more than shrinkage | contraction start temperature, it suppresses that a heat-shrinkable laminated film shrinks rapidly, and it is easy to control the shrinkage | contraction rate suitable in shrink packaging.

<(II) layer>
The layer (II) in the heat-shrinkable laminated film of the present invention is mainly composed of a polyamide-based elastomer whose hard segment / soft segment ratio is hard segment / soft segment = 10-60 mass% / 40-90 mass%. It is comprised from a resin composition.

  The polyamide-based elastomer is a copolymer having a hard segment mainly composed of polyamide and a soft segment mainly composed of polyol.

  As the polyamide constituting the hard segment of the polyamide-based elastomer used in the (II) layer of the heat-shrinkable laminated film of the present invention, for example, polyamide derived from a diamine component and a dicarboxylic acid component, or by ring-opening polymerization of lactams Any of polyamide, polyamide derived from aminocarboxylic acid, copolymerized polyamide thereof, and mixed polyamide thereof may be used. Examples of the diamine component include ethylenediamine, tetramethylenediamine, hexamethylenediamine, decamethylenediamine, 2,3,4,2,4,4-trimethylenehexamethylenediamine, 1,3- or 1,4-bis (amino Methyl) cyclohexane, bis (p-aminohexyl) methane, phenyldiamine, m-xylenediamine, p-xylenediamine, and the like include aliphatic, alicyclic or aromatic diamines, and examples of the dicarboxylic acid component include adipic acid And aliphatic, alicyclic or aromatic dicarboxylic acids such as suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid and isophthalic acid. Examples of the lactams include caprolactam and lauryl lactam. Examples of the aminocarboxylic acid include ω-aminocaproic acid, ω-aminoenanoic acid, aminoundecanoic acid, and 1,2-aminododecanoic acid.

  The hard segment constituting the polyamide-based elastomer may be a combination of two or more hard segments other than polyamide, such as polyester, polyolefin, and polyurethane, in addition to the polyamide as the main component. Therefore, the bond between the hard segment and the soft segment mainly composed of a polyol described later is at least one selected from an amide bond, an ester bond, an ether bond, a urethane bond, an imide bond, and the like. For this reason, the molecular end of the hard segment needs to be modified with a functional group having reactivity with the molecular end functional group of the soft segment. Examples of these functional groups include a carboxyl group, a hydroxyl group, an amino group, an acid anhydride group, an oxazoline group, an epoxy group, an isocyanate group, and a urea group.

  Examples of the polyol constituting the soft segment of the polyamide-based elastomer include polyether polyol, polyester polyol, polyester ether polyol, polycarbonate polyol, and modified products thereof. These include polyether ester amides having polyether polyol segments; polyether ester amide imides having polyether polyol segments; polyether esters having polyether polyol segments; polyether amides having polyether polyol segments , Polyether urethane, polyether urea and the like are included, and polyether polyol is preferable.

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

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

  Further, as the polyester ether polyol, the aliphatic dicarboxylic acid, the aromatic dicarboxylic acid, the aliphatic dicarboxylic acid, and an ester compound thereof, or an acid anhydride, glycol such as diethylene glycol, propylene oxide adduct, etc., or And a condensation reaction product with a mixture thereof.

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

It is important that the ratio of the hard segment to the soft segment of the polyamide-based elastomer used in the present invention is in the range of hard segment / soft segment = 10-60 mass% / 40-90 mass%.
The lower limit of the ratio of the hard segment is preferably 13% by mass or more, more preferably 16% by mass or more, and the upper limit is preferably 50% by mass or less, more preferably 40% by mass or less. The lower limit of the soft segment ratio is preferably 50% by mass or more, more preferably 60% by mass or more, and the upper limit is preferably 87% by mass or less, more preferably 84% by mass or less.
By making the ratio of the hard segment 10% by mass or more, the shape retention of the polyamide-based elastomer and the pseudo-crosslinking point effect as a thermoplastic elastomer can be maintained. By setting the soft segment ratio to 40% by mass or more, the adhesive strength can be improved.
Furthermore, by controlling the ratio of the hard segment to 60% by mass or less, the elastic modulus of the (II) layer composed of the resin composition containing a polyamide-based elastomer as a main component is suppressed, and (II) during stretching The stretching stress applied to the layer can be relaxed. Therefore, the excessive shrinkage stress received at the time of shrinkage | contraction of a heat-shrinkable laminated film can be suppressed, and the delamination of the heat-shrinkable laminated film resulting from an excessive shrinkage stress can be suppressed.
That is, the ratio of the hard segment to the soft segment of the polyamide-based elastomer is hard segment / soft segment = 10 to 60% by mass / 40 to 90% by mass. From the viewpoint of suppressing delamination in the present invention, it is important in the present invention.

  The polyamide elastomer used in the present invention preferably has a hardness of 50 or less in terms of shear D and a range of 60 to 90 in terms of shear A.

  Any known production method can be used for producing the polyamide-based elastomer used in the present invention.

  The lower limit and upper limit of the weight average molecular weight of the polyamide-based elastomer used in the present invention are not particularly limited, but the lower limit is preferably 30,000 or more, more preferably 40,000 or more. More preferably, 50,000 or more. Moreover, as an upper limit, 1,000,000 or less is preferable, 900,000 or less is more preferable, and 800,000 or less is further more preferable.

The lower limit value and upper limit value of the melt viscosity of the polyamide-based elastomer used in the present invention are not particularly limited, but the lower limit value is the melt viscosity of shear at a measurement temperature of 200 ° C. and a shear rate of 100 sec ⁻¹ . Is preferably 80 Pa · s or more, more preferably 90 Pa · s or more, and further preferably 100 Pa · s or more. The upper limit is preferably 300,000 Pa · s or less, more preferably 200,000 Pa · s or less, and even more preferably 100,000 Pa · s or less.

  Typical examples of polyamide elastomers preferably used in the present invention include “Pebax” manufactured by Arkema, “Uvesta XPA” manufactured by Ube Industries, “Pelestat” manufactured by Sanyo Chemical Industries, Ltd., and the like. Listed as available. These polyamide-based elastomers may be used alone or in combination of two or more.

<(III) layer>
The (III) layer in the heat-shrinkable laminated film of the present invention is composed of a resin composition containing ethylene vinyl alcohol resin as a main component.

  The ethylene vinyl alcohol copolymer used in the heat-shrinkable laminated film of the present invention is a copolymer containing an ethylene monomer and a vinyl alcohol monomer, but other monomers are further copolymerized. May be. Examples of other monomers include propylene, isobutene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and other α-olefins, vinyl acetate (Meth) acrylic acid ester, vinyl fluoride, vinylidene fluoride, vinyl chloride, vinylidene chloride, carbon monoxide, acrylonitrile, styrene and the like. Further, hydroxy group-containing α-olefins such as hydroxy-containing α-olefins such as 3-buten-1-ol, 4-penten-1-ol, 3-butene-1, and 2-diol, esterified products thereof, and acylated products thereof. Olefin derivatives, unsaturated carboxylic acids or salts thereof, partial alkyl esters, fully alkyl esters, nitriles, amides or anhydrides, unsaturated sulfonic acids or salts thereof, and vinylsilane compounds may also be included. An ethylene vinyl alcohol copolymer having a 1,2-glycol bond as a partial structure can also be used. In addition, an ethylene vinyl alcohol copolymer partially modified with a compound capable of reacting with a hydroxyl group such as butyraldehyde can also be used. Further, it may be post-modified such as urethanization, acetalization, cyanoethylation, oxyalkyleneation. A modified product of an ethylene vinyl alcohol copolymer modified with a functional group such as an acid anhydride can also be used. These may be used alone or, if necessary, may be blended with two or more ethylene vinyl alcohol copolymers having different physical properties such as composition and viscosity such as ethylene content and saponification degree.

  The ethylene content ratio of the ethylene vinyl alcohol copolymer is preferably 20 mol% or more and 50 mol% or less, more preferably 22 mol% or more and 45 mol% or less, and further preferably 24 mol% or more and 40 mol% or less. The vinyl alcohol content of the ethylene vinyl alcohol copolymer is preferably 50 mol% or more and 80 mol% or less, more preferably 55 mol% or more and 78 mol% or less, and further preferably 60 mol% or more and 76 mol% or less. When the ethylene content ratio of the ethylene vinyl alcohol copolymer is 20 mol% or more and 50 mol% or less, it is excellent in the balance between moldability and gas barrier property, and is preferable.

  The melt flow rate (MFR) of the ethylene vinyl alcohol copolymer is not particularly limited, but usually the MFR at a temperature of 210 ° C. and a load of 2.16 kg is 0.03 to 60 g / 10 min. Preferably, it is 0.3-30 g / 10min. If the MFR is in the above range, the back pressure of the extruder does not become too high during the molding process and the productivity is excellent.

  The melting point of the ethylene vinyl alcohol copolymer can be determined according to the monomer ratio to be constituted, but is preferably 150 ° C. or higher, more preferably 155 ° C. or higher, and further preferably 160 ° C. or higher.

  As the ethylene vinyl alcohol copolymer, for example, commercially available products such as “EVAL” (manufactured by Kuraray Co., Ltd.) and “Soarnol” (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) can be used.

<Layer structure>
The composition of the heat-shrinkable laminated film of the present invention is the (I) layer, (II) layer, and (III) layer composed of the following resin composition: (I) layer / (II) layer / (III) layer It is important to have three layers that are adjacent in this order.
(I) Layer: Resin composition mainly composed of a thermoplastic resin (II) Layer: Polyamide system in which the ratio of hard segment to soft segment is hard segment / soft segment = 10-60 mass% / 40-90 mass% Resin composition mainly composed of elastomer (III) layer: Resin composition mainly composed of ethylene vinyl alcohol copolymer

Moreover, if the heat-shrinkable laminated film of the present invention has three layers adjacent in the order of (I) layer / (II) layer / (III) layer, other layers can be further added.
For example, (I) layer / (II) layer / (III) layer / (IV) layer, (IV) layer / (I) layer / (II) layer / (III) layer, or (I) Layer / (II) layer / (III) layer / (IV) layer / (V) layer, (IV) layer / (V) layer / (I) layer / (II) layer / (III) layer, (V) A five-layer structure of layer / (I) layer / (II) layer / (III) layer / (IV) layer is mentioned. In particular, in order to improve gas barrier properties, from the viewpoint of protecting the (III) layer, (I) layer / (II) layer / (III) layer / (IV) layer, (I) layer / (II) layer / ( A configuration of III) layer / (IV) layer / (V) layer, (V) layer / (I) layer / (II) layer / (III) layer / (IV) layer, etc. is preferable.
In particular, considering the adhesion between the (III) layer and other layers, it is more preferable to have four layers adjacent in the order of (I) layer / (II) layer / (III) layer / (II) layer, (I) layer / (II) layer / (III) layer / (II) layer / (IV) layer, 4 types and 5 layers, (I) layer / (II) layer / (III) layer / (II) The three-layered five-layer configuration of layer / (I) layer is most preferable from the viewpoints of curling suppression of the heat-shrinkable laminated film, retention of mechanical properties, and moldability into sheet rolls.
Furthermore, if the heat-shrinkable laminated film of the present invention has three layers adjacent in the order of (I) layer / (II) layer / (III) layer, the number of layers is added in addition to the above-mentioned layers. The number of added layers is not limited.

<Lamination ratio>
The thickness ratio of each layer of the heat-shrinkable laminated film of the present invention is not particularly limited, but preferably the lower limit of the ratio of the thickness of the (III) layer to the thickness of the entire heat-shrinkable laminated film is 5% or more is preferred, more preferably 10% or more, and the upper limit is preferably 60% or less, more preferably 50% or less. If the thickness ratio of the (III) layer is within the above range, the film is excellent in oxygen barrier properties and shrinkability, which is preferable.
The total thickness of the heat-shrinkable laminated film of the present invention is not particularly limited, but is preferably thinner from the viewpoints of transparency, shrinkage characteristics, raw material costs, and the upper limit is preferably 500 μm or less, More preferably, it is 400 micrometers or less, More preferably, it is 300 micrometers or less. Although a minimum is not specifically limited, When the handling property of a heat-shrinkable laminated film is considered, 20 micrometers or more are preferable.

<Other additives>
Each layer constituting the heat-shrinkable laminated film of the present invention includes, in addition to the above-described components, recycled resin generated from trimming loss such as ears, silica, talc, etc. within a range that does not impair the effects of the present invention. , Inorganic particles such as calcium carbonate kaolin, pigments such as titanium oxide and carbon black, flame retardants, weathering stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, crosslinkers, lubricants, nucleating agents, plasticizers, Additives such as an anti-aging agent, an antioxidant, a light stabilizer, an ultraviolet absorber, a neutralizing agent, an antifogging agent, an antiblocking agent, a slip agent, and a coloring agent can be appropriately added.

<Heat shrinkability>
In the heat-shrinkable laminated film of the present invention, it is preferable that the heat shrinkage rate described later satisfies a specific range in order to obtain a film that can realize adhesion according to various shapes of contents.

<Heat shrinkage>
In the heat-shrinkable laminated film of the present invention, the heat shrinkage rate in the main shrinkage direction when immersed in warm water at 80 ° C. for 10 seconds is preferably 20% or more, more preferably 30% or more, and further preferably 35%. That's it. The upper limit is not particularly limited, but is preferably 80% or less.
In addition, the thermal shrinkage rate in the main shrinkage direction when immersed in warm water at 50 ° C. for 10 seconds is preferably less than 3%, more preferably less than 2%, and even more preferably less than 1%. Most preferably, it is 0% where the dimensions do not change.
Further, the thermal shrinkage rate in the main shrinkage direction when immersed in warm water at 100 ° C. for 10 seconds is preferably 40% or more, more preferably 50% or more, and further preferably 60% or more.
By setting the heat shrinkage rate within the above range, it is possible to improve the adhesion to contents having various shapes, particularly a large difference between a thick part and a thin part. The “main shrinkage direction” refers to the direction having the largest heat shrinkage rate in the surface direction of the heat shrinkable laminated film. If the heat-shrinkable laminated film has a three-dimensional shape such as a bottle shape or a tube shape, the main shrinkage direction can be derived by cutting the molded product into a planar shape (sheet shape). In addition, in order to make a heat contraction rate into the said range, it can adjust with extending | stretching temperature and a draw ratio.

  Further, the shrinkage rate in the direction orthogonal to the main shrinkage direction is not particularly limited. In order to improve the adhesion according to the shape of the object to be packaged, a higher one may be preferable, and a lower one may be preferable, and it is necessary to select appropriately. Further, the heat shrinkage rate in the direction orthogonal to the direction in which the shrinkage rate is expressed can be adjusted in the same manner as the heat shrinkage rate in the shrinkage direction.

<Shrinkage stress>
In the heat-shrinkable laminated film of the present invention, it is most important that the maximum shrinkage stress in the main shrinkage direction when immersed in silicon oil at 100 ° C. for 1 minute is in the range of 3.0 MPa to 9.5 MPa. The lower limit of the maximum shrinkage stress is preferably 3.5 MPa or more, more preferably 4.0 MPa or more, and the upper limit is preferably 9.0 MPa or less, more preferably 8.5 MPa or less. If the maximum shrinkage stress is less than 3.0 MPa, excess wrinkles that are generated at the initial stage of shrinkage to the coating cannot be eliminated during the shrinkage process, and the shrink-finished appearance is not good. On the other hand, when it is larger than 9.5 MPa, the container is deformed when contracted, which is not preferable. On the other hand, when the maximum shrinkage stress is larger than 9.5 MPa, the shrinkage stress applied to each layer at the time of shrinkage is excessive, and it is easy to exceed the admissibility of the adhesive force held by the (II) layer, and delamination is likely to occur.
In addition, in order to make shrinkage stress into the said range, it can adjust by mix | blending each layer with the composition prescribed | regulated by this invention, a draw ratio, and heat processing temperature. Among them, the ratio of the hard segment and the soft segment of the polyamide-based elastomer in the layer (II) composed of the resin composition containing a polyamide-based elastomer as a main component is hard segment / soft segment = 10-60 mass% / 40- The most effective is 90% by mass.

<All haze>
The heat-shrinkable laminated film of the present invention preferably has a total haze value of 10% or less, more preferably 8% or less, and 6% or less when measured according to JIS K7136. Is more preferable. If the total haze value is 10% or less, the visibility of the covering body to which the film is attached can be sufficiently obtained.

<Normal temperature tensile elongation at break>
The heat-shrinkable laminated film of the present invention has a tensile elongation at break of 100 (or MD) in the take-off (flow) direction of the film-like material, measured at an ambient temperature of 23 ° C. and a tensile speed of 200 mm / min. % Or more, more preferably 150% or more, still more preferably 200% or more. When the tensile elongation at break in an environment of 23 ° C. is within the above range, it is preferable that problems such as breakage of the film-like material during the printing / bag-making process hardly occur. Further, it is preferable that bag breakage or the like hardly occurs from a close contact portion with the coating.
In order to set the tensile elongation at break at an atmospheric temperature of 23 ° C. within the above range, adjustment of blending of each layer, adjustment of extrusion conditions in the film forming process, adjustment of stretching conditions, adjustment of heat shrinkage ratio, adjustment of lamination ratio, etc. Can be adjusted by appropriately performing the above.

<Low temperature tensile elongation at break>
The heat-shrinkable laminated film of the present invention has a tensile elongation at break of 100 (or MD) in the direction of film take-up (flow) measured at an atmospheric temperature of 0 ° C. and a tensile speed of 100 mm / min. % Or more, more preferably 150% or more, still more preferably 200% or more. When the tensile elongation at break in the environment of 0 ° C. is within the above range, it is preferable that problems such as breakage of the film-like material during the printing / bag making process are unlikely to occur. Further, it is preferable that bag breakage or the like hardly occurs from a close contact portion with the coating.
To set the tensile elongation at break at an atmospheric temperature of 0 ° C. within the above range, adjustment of the composition of each layer, adjustment of extrusion conditions in the film forming process, adjustment of stretching conditions, adjustment of heat shrinkage ratio, adjustment of lamination ratio, etc. Can be adjusted by appropriately performing the above.

<Oxygen permeability>
The heat-shrinkable laminated film of the present invention preferably has an oxygen permeability at 23 ° C. · 0 ° C. RH of 20 cc / m ² · day · atm or less, more preferably 10 cc / m ² · day · atm or less. More preferably, it is 5 cc / m ² · day · atm or less. When the oxygen permeability is within the above range, the oxygen barrier property is sufficient.

<Manufacturing method>
The method for producing the heat-shrinkable laminated film of the present invention is not particularly limited and can be produced by a conventionally known method, but a film-like form is preferable. Here, the “film-like product” has a meaning that encompasses a thick sheet to a thin film. The film-like material may be either flat or tube-like, but from the viewpoint of productivity (a few products can be taken in the width direction of the raw sheet) and printing on the inner surface, it is flat. Is preferred. As a method for producing a flat film, for example, a method of obtaining a film by melting a resin using a plurality of extruders, co-extruding from a T-die, cooling and solidifying with a cooling roll, and winding with a winder Can be illustrated. In order to impart shrinkage characteristics, for example, the resin is melted using a plurality of extruders, co-extruded from a T-die, cooled and solidified with a cooling roll, roll-stretched in the vertical direction, and tenter-stretched in the horizontal direction. An example is a method of obtaining a film by annealing, cooling, and winding with a winder. Moreover, the method of cutting open the film manufactured by the tubular method and making it flat is also applicable.
The extrusion temperature is preferably about 180 to 260 ° C, more preferably 190 to 250 ° C. Controlling the dispersion state of the material by optimizing the extrusion temperature and the shear state is also effective in bringing various physical and mechanical properties of the film described below to desired values.

  The manufacturing method of the heat-shrinkable laminated film of the present invention can be manufactured by stretching the film-like product obtained by the above-described manufacturing method. For example, the resin is melted using an extruder, extruded from a T-die, cooled and solidified with a cooling roll, and roll-stretched in the longitudinal direction (film flow direction) or in the transverse direction (perpendicular to the film flow direction). ) To at least one direction. Moreover, after extending | stretching to a vertical direction, you may extend | stretch to a horizontal direction and may extend | stretch to a vertical direction after extending | stretching to a horizontal direction. Furthermore, after extending | stretching to a vertical direction, you may extend | stretch to a horizontal direction and may extend | stretch further to the vertical direction. Moreover, you may extend | stretch simultaneously in the vertical direction and a horizontal direction with a simultaneous biaxial stretching machine. Furthermore, a tubular film may be radially stretched by an internal pressure by a tubular method, and a method of cutting a tubular material stretched by a tubular method into a planar shape is also included.

  The stretching ratio is preferably 2 to 10 times in the longitudinal direction, 2 to 10 times in the transverse direction, more preferably 3 to 6 times in the longitudinal direction, and about 3 to 6 times in the transverse direction in applications for contraction in two directions. is there. On the other hand, in an application mainly shrinking in one direction, the direction corresponding to the main shrinking direction is preferably 2 to 10 times, more preferably 4 to 8 times, and the direction perpendicular thereto is preferably 1.00 to 2.00. It is desirable to select a magnification ratio that is substantially in the category of uniaxial stretching, such as 1.0 times, more preferably 1.01 to 1.50 times. In addition, 1.00 time points out the case where it is not extending | stretching.

  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 laminated film, but is generally 60 ° C. or higher, preferably 70 ° C. or higher, and the upper limit is 100 ° C. or lower, preferably 90 It is controlled in the range of ℃ or less.

  The stretched laminated film can be subjected to 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 shrinkage characteristics, if necessary.

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

<Packaging materials>
The heat-shrinkable laminated film of the present invention can be suitably used as various packaging materials. As a specific example when used as a packaging material, for example, a bag is formed using the heat-shrinkable laminated film of the present invention, and contents such as food, pharmaceuticals, and industrial chemicals are stored therein. The air can be removed and subjected to heat treatment to be shrunk to form a package.

The present invention 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. The direction of taking (flowing) the film-like material is described as “longitudinal” direction (or MD), and the perpendicular direction thereof is described as “transverse” direction (or TD).
<Measurement method>

(1) 23 ° C. tensile strength at break, tensile elongation at break (MD)
The obtained heat-shrinkable laminated film was cut into a size of 120 mm in MD and 15 mm in TD, and the tensile elongation at break of MD of the film at an ambient temperature of 23 ° C. was measured at a tensile speed of 200 mm / min according to JIS K7127. Then, the average value of 10 measurements was measured and evaluated according to the following criteria.

(2) 23 ° C. tensile strength at break, tensile elongation at break (TD)
The obtained heat-shrinkable laminated film was cut into a size of 120 mm for TD and 15 mm for MD, and in accordance with JIS K7127, at a tensile speed of 200 mm / min, and at a tensile temperature of 23 ° C., the tensile strength at break of the TD of the film. Was measured, and the average value of 10 measurements was measured and evaluated according to the following criteria.

(3) 0 ° C. tensile breaking strength, tensile breaking elongation (MD)
The obtained heat-shrinkable laminated film was cut into a size of 120 mm in MD and 15 mm in TD, and in accordance with JIS K7127, a tensile breaking elongation in the film take-off direction (MD) at an atmospheric temperature of 0 ° C. at a tensile speed of 100 mm / min. The degree was measured and the average value of 10 measurements was measured.

(4) Oxygen permeability The obtained heat-shrinkable laminated film was measured at 23 ° C. and 0% RH using an OXY-TRAN100 type oxygen permeability measuring device manufactured by Modern Control, and the oxygen permeability was measured.

(5) Heat Shrinkage The obtained heat-shrinkable laminated film was cut into a size of MD 10 mm and TD 200 mm, and immersed in a hot water bath at 50 ° C., 80 ° C., and 100 ° C. for 10 seconds, and the amount of TD shrinkage was measured. Further, the obtained heat-shrinkable laminated film was cut into a size of TD 5 mm and MD 200 mm, and immersed in warm water baths of 50 ° C., 80 ° C., and 100 ° C. for 10 seconds, and the amount of shrinkage of MD was measured. The thermal shrinkage rate was expressed as a percentage of the shrinkage amount relative to the original size before shrinkage.

(6) Total haze value In order to evaluate the transparency of the obtained heat-shrinkable laminated film, the total haze value was measured according to JIS K7136.

(7) Tape peeling test Along with the take-up direction (MD) of the obtained heat-shrinkable laminated film, a 18 mm wide transparent adhesive tape made of Nichiban was applied, and the tape and the film were brought into close contact with a horse-shoe-shaped jig. Then, the state of the film-like product when the adhesive tape was instantly peeled was evaluated.
○: When the adhesive tape is peeled off, the state before peeling is maintained and the film does not peel. Δ: When the adhesive tape is peeled off, the film is partially peeled. ×: When the adhesive tape is peeled off, the film is peeled off. When peeling occurs on the entire surface

(8) Maximum shrinkage stress In order to measure the shrinkage stress in the main shrinkage direction (TD) of the obtained heat-shrinkable laminated film, it is cut into a size of MD 10 mm and TD 70 mm, and the chuck load cell is free from sagging at a chuck interval of 50 mm. Fixed. Thereafter, the sample piece was immersed in a 100 ± 0.5 ° C. silicon bath for 1 minute, and the shrinkage stress of TD was measured. At this time, the maximum value of the shrinkage stress per minute was calculated as the maximum shrinkage stress. The shrinkage stress was calculated by applying the following formula.
Shrinkage stress (MPa) = stress applied to load cell (N) / cross-sectional area of sample piece (mm ² )

(9) Delami during shrinkage In order to evaluate the delami during shrinkage of the obtained heat-shrinkable laminated film, it was cut into a size of MD 100 mm and TD 200 mm, and as shown in FIG. 1, the length was 130 mm, the width was 170 mm, and the width was 5 mm. The two TD ends of the film were sandwiched between two rectangular metal frames hollowed out by 15 mm and immersed in warm water at 100 ° C. for 10 seconds. Then, the metal frame was removed, the state of the film TD end part was confirmed, and the following criteria were used for judgment.
○: No delamination is observed at the end of the film TD. X: Delamination is observed at the end of the film TD.

The raw materials used in each example and comparative example are as follows.
<Thermoplastic resin>
Polyester containing 1,4-cyclohexanedimethanol: 21.8 mol%, ethylene glycol: 76.1 mol%, diethylene glycol: 2.0 mol%, terephthalic acid: 90.5 mol%, isophthalic acid: 9.5 mol% as constituent components Resin (abbreviated as “PEs1”)
Polyester resin containing 1,4-butanediol: 100 mol%, terephthalic acid: 90 mol%, and isophthalic acid: 10 mol% as constituent components (abbreviated as “PEs-2”)
<Ethylene vinyl alcohol copolymer>
Product name: Eval SP482B, ethylene content 32 mol%, MFR = 4.1 g / 10 min, density = 1.16 g / cm ³ (abbreviated as “EVOH1”)
<Polyamide elastomer>
Polyamide-based elastomer (abbreviated as “AD1”) containing 12 nylon as a hard segment and polytetramethylene glycol as a soft segment, density 1.01 g / cm ³ , melting point: 134 ° C., MFR (measurement temperature 235) C, measurement load 1 kg): 10 g / 10 min, shear hardness A: 75, hard segment / soft segment ratio = 20 mass% / 80 mass%
Polyamide-based elastomer (abbreviated as “AD2”) containing 12 nylon as a hard segment and polytetramethylene glycol as a soft segment, density 1.01 g / cm ³ , melting point: 144 ° C., MFR (measurement temperature 235) ° C, measuring load 1 kg): 8 g / 10 min, shear hardness A: 83, hard segment / soft segment ratio = 27 mass% / 73 mass%
Polyamide-based elastomer (abbreviated as “AD3”) containing 12 nylon as a hard segment and polyethylene glycol as a soft segment, density 1.04 g / cm ³ , melting point: 170 ° C., MFR (measurement temperature 235 ° C., Measurement load 1 kg): 7 g / 10 min, shear hardness D: 60, hard segment / soft segment ratio = 74 mass% / 26 mass%

<Example 1>
(I) As a resin composition used for the layer, 85% by mass of “PEs1” and 15% by mass of “PEs2” were mixed, and then charged into a twin-screw extruder (screw diameter: 35 mmφ), and the extruder set temperature After forming on a strand at 240 ° C., it was rapidly cooled in a water tank, and the strand was cut to obtain a compound pellet (abbreviated as “PEs compound”).
Thereafter, according to the composition and configuration shown in Table 1, (PE) compound is used as a raw material constituting the layer (I), and polyamide-based elastomer “AD1” is used as a raw material constituting the layer (II). Using ethylene vinyl alcohol copolymer “EVOH1” as a raw material constituting the layer, each is introduced into three single-screw extruders, melt-kneaded in each single-screw extruder, a conduit, a merge block, In the equipment capable of co-extrusion of (I) layer / (II) layer / (III) layer / (II) layer / (I) layer jointed in the order of 3 types and 5 types of multi-manifold caps, 3 types Five layers of laminates were collected.
At this time, the extruder set temperature for the (I) layer is 250 ° C., the extruder set temperature for the (II) layer and the (III) layer is 190 to 200 ° C., and the thickness ratio of each layer is (I) layer / (II) layer / (III) layer / (II) layer / (I) layer = 70 μm / 15 μm / 30 μm / 15 μm / 70 μm co-extruded, taken up with a cast roll at 70 ° C., cooled and solidified, unstretched A sheet-like laminate was obtained. Next, the obtained sheet-like laminate was stretched at a stretching temperature of 80 ° C. at a stretching ratio of 5 times in the width direction using a film tenter, and then heat-treated at a heat treatment temperature of 80 ° C. to obtain a thickness of 40 μm. A heat-shrinkable laminated film was obtained. This was evaluated. The results are shown in Table 1.

<Example 2>
(II) An unstretched sheet-like laminate having a thickness of 200 μm in the same manner as in Example 1 except that the polyamide-based elastomer “AD1” is changed to the polyamide-based elastomer “AD2” as a raw material constituting the layer. Got. Thereafter, the obtained sheet-like laminate was stretched and heat-treated in the same manner as in Example 1 to obtain a heat-shrinkable laminate film having a thickness of 40 μm. This was evaluated. The results are shown in Table 1.

<Comparative Example 1>
(II) A sheet-like laminate having a thickness of 200 μm was obtained in the same manner as in Example 1 except that the polyamide-based elastomer “AD1” was changed to the polyamide-based elastomer “AD3” as a raw material constituting the layer. . Thereafter, the obtained sheet-like laminate was stretched and heat-treated in the same manner as in Example 1 to obtain a heat-shrinkable laminate film having a thickness of 40 μm. This was evaluated. The results are shown in Table 1.

  The heat-shrinkable laminated films of the present invention obtained in Example 1 and Example 2 were excellent in break resistance, break resistance at low temperature, transparency, oxygen barrier properties, and heat shrink characteristics. Furthermore, it was confirmed that delamination during contraction was suppressed. On the other hand, the heat-shrinkable laminated film obtained in Comparative Example 1 showed delamination during shrinkage. This is probably because the ratio of the hard segment to the soft segment of the polyamide-based elastomer defined by the present invention and the maximum shrinkage stress deviate, so that the stress applied to each layer at the time of shrinkage is excessive and delamination occurs.

  Although the present invention has been described with reference to the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein. The heat shrinkable laminated film with such changes is also included in the technical scope of the present invention. Must be understood.

  The heat-shrinkable laminated film of the present invention is excellent in oxygen gas barrier property, shrinkage and transparency, and is excellent in adhesion between layers. Therefore, the heat-shrinkable laminated film is used for packaging foods, pharmaceuticals, industrial chemicals, etc. Therefore, the contents can be prevented from being altered, and can be suitably used as a packaging material for these applications.

DESCRIPTION OF SYMBOLS 1 Heat-shrinkable laminated film of this invention 2 Rectangular metal frame 3 Fixing tool

Claims (5)

The (I) layer, (II) layer, and (III) layer composed of the following resin composition have three layers adjacent to each other in the order of (I) layer / (II) layer / (III) layer, and 100 ° C. A heat-shrinkable laminated film having a maximum shrinkage stress in the main shrinkage direction of 3.0 MPa or more and 9.5 MPa or less when immersed in a silicon bath for 1 minute.
(I) Layer: Resin composition mainly composed of a thermoplastic resin (II) Layer: Polyamide system in which the ratio of hard segment to soft segment is hard segment / soft segment = 10-60 mass% / 40-90 mass% Resin composition mainly composed of elastomer (III) layer: Resin composition mainly composed of ethylene vinyl alcohol copolymer   The thermal contraction rate in the main contraction direction when immersed in 50 ° C. warm water for 10 seconds is less than 3%, and the thermal contraction rate in the main contraction direction when immersed in 80 ° C. warm water for 10 seconds is 20% or more, The heat-shrinkable laminated film according to claim 1, wherein the heat-shrinkage rate in the main shrinkage direction when immersed in warm water at 100 ° C. for 10 seconds is 40% or more.   The heat-shrinkable laminated film according to claim 1 or 2, wherein an ethylene content ratio of the ethylene vinyl alcohol copolymer is 20 mol% or more and 50 mol% or less.   The heat-shrinkable laminated film according to any one of claims 1 to 3, wherein the thermoplastic resin is a polyester resin. The heat-shrinkable laminated film according to claim 4, wherein the polyester resin comprises at least two of a polyethylene terephthalate copolymer (A) and a polybutylene terephthalate copolymer (B).

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