JP2016199745A - Polar group modified polymer composition and multilayer structure using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polar group modified polymer composition which improves moisture resistance as the whole multilayer structure and can suppress deterioration in properties by moisture absorption, in a multilayer structure containing a layer in which properties are lowered by moisture absorption, and to provide a multilayer structure using the same.SOLUTION: A polar group modified polymer composition, which contains a polymer (polar group modified polymer) having an aliphatic hydrocarbon monomer unit containing a carbon-carbon double bond modified with a polar-group containing compound and a hydrate-forming alkaline earth metal salt having a predetermined water absorption property, can suppress deterioration in properties by moisture absorption of other layers contained in the multilayer structure without affecting the appearance of the multilayer structure. The composition can be used as an adhesive resin layer for a hydrophobic resin layer and a hygroscopic layer such as an EVOH resin layer.SELECTED DRAWING: None

Description

  The present invention relates to a polar group-modified polymer composition that can be used for improving moisture resistance and a multilayer structure using the same, and more particularly, to improve moisture resistance of a multilayer structure including a resin layer having poor moisture resistance. The present invention relates to a polar group-modified polymer composition that can be used in the present invention and a multilayer structure including the polar group-modified polymer composition layer.

  In general, a film made of a thermoplastic resin is used as a packaging film for food or the like. The packaging film is required to have gas barrier properties such as oxygen barrier properties from the viewpoints of strength as a film and freshness of food. Further, even when the package is stored for a long period of time under high temperature and high humidity such as the rainy season, moisture resistance is also required so that appearance deterioration of the package does not become a problem. Furthermore, since the package may be subjected to hot water treatment such as retort treatment, it is required that the film strength, appearance, gas barrier properties, and the like due to such treatment be suppressed.

Since it is difficult to satisfy all of the above requirements with one kind of thermoplastic resin film, a multilayer film in which a plurality of kinds of resin films are laminated is usually used as a packaging film.
For example, a multilayer film in which both sides of a film having a gas barrier property are sandwiched by protective films having excellent strength and moisture resistance, and an adhesive resin between them in order to improve the adhesive strength between the gas barrier layer and the protective layer. A multilayer film having layers interposed between the layers is used as a packaging film.

In such a multilayer film having gas barrier properties, for example, a saponified ethylene-vinyl ester copolymer (hereinafter sometimes referred to as “EVOH resin”) is used as a cas barrier layer, and both surfaces of the EVOH resin layer are used. Is a multilayer film sandwiched between polyolefin films.
However, it is known that the gas barrier performance is deteriorated when a package packaged with a multilayer film using EVOH resin as a gas barrier layer is subjected to a treatment exposed to hot water for a long time, such as a retort treatment. Such a decrease in gas barrier properties is due to the fact that moisture enters the EVOH resin layer from the edge of the multilayer film, etc. due to the hot water treatment, the hydrogen bonds between the molecules of the EVOH resin are broken, and oxygen molecules easily enter from the outside. It is considered.

  As a method for suppressing a decrease in gas barrier performance due to hot water treatment, it is known to add a hydrate-forming metal salt as a desiccant to the layers constituting the multilayer structure. For example, Patent Document 1 includes an EVOH resin layer as a gas barrier layer, and this EVOH resin layer is sandwiched between thermoplastic resin layers containing a dehydrate of disodium succinate hydrate as a desiccant. However, it was shown that excellent gas barrier properties were maintained even after the hot water treatment.

JP 2010-59418 A

  However, the multilayer structure described in Patent Document 1 is excellent in gas barrier properties after hydrothermal treatment, but when left under high temperature and high humidity, the desiccant is excessive in excess of the hygroscopicity inside the thermoplastic resin. Takes in moisture and dissolves in water. The water-soluble desiccant causes poor appearance of the multilayer structure. In severe cases, the water-soluble desiccant moves to the interface between the thermoplastic resin composition layer and the adhesive resin layer and delamination occurs. May cause.

  This invention is made | formed in view of the above situations, The place made into the objective includes the layer (moisture absorption layer) which a characteristic falls by moisture absorption like the EVOH resin layer. In a multilayer structure, it is providing the polar group modified polymer composition which can suppress the characteristic fall by moisture absorption, without affecting the external appearance of a multilayer structure, and a multilayer structure using the same.

  The present inventor suppresses deterioration of the characteristics of the entire multilayer structure due to moisture absorption without affecting the appearance of the multilayer structure in the entire multilayer structure including the resin layer (moisture absorption layer) whose characteristics can be degraded by moisture absorption. With the goal of achieving this, various desiccants added to the polar group-modified polymer were studied and the present invention was completed.

  That is, the polar group-modified polymer composition of the present invention is (A) a polar group-modified polymer in which a polymer having an aliphatic hydrocarbon monomer unit containing a carbon-carbon double bond is modified with a polar group-containing compound. A polymer; and (B) a hydrate-forming alkaline earth metal salt that satisfies the following water absorption characteristics (α), and further comprises the following water absorption characteristics (β) and / or (γ) Is preferably satisfied.

(Α) When the alkaline earth metal salt (B) is left at 40 ° C. and 90% relative humidity with respect to the crystallization water content (Y) in the maximum hydrate of the alkaline earth metal salt (B). The ratio (X ₅ / Y) of water absorption (X ₅ ) per 100 g of the alkaline earth metal salt (B) for 5 days is 0.2 to 2.0.
(Β) The water absorption (Z) per 100 g after 24 hours when the alkaline earth metal salt (B) is allowed to stand at 40 ° C. and 90% relative humidity is 10 g or more.
(Γ) It has a maximum point of water absorption when left at 40 ° C. and 90% relative humidity.

  The alkaline earth metal salt (B) has a complete dehydration or water content of a mixture of alkaline earth metal salts of one kind of acid selected from the group consisting of lactic acid, silicic acid, phosphoric acid, and citric acid. % Of partial dehydrated product or a mixture thereof is preferable. The content weight ratio (A / B) of the polar group-modified polymer (A) and the hydrate-forming alkaline earth metal salt (B) is more than 50 / less than 50 to 99/1. preferable.

  The polar group-modified polymer (A) is preferably a carboxyl group-modified olefin polymer.

  The multilayer structure of the present invention is characterized by having at least one layer comprising the polar group-modified polymer composition of the present invention.

Further, a gas barrier layer having an oxygen permeability of 100 mL · 20 μm / (m ² · day · atm) or less measured at 20 ° C. and 65% relative humidity according to the method described in JIS-K7126 (isobaric method). The gas barrier layer preferably includes, for example, a saponified ethylene-vinyl ester copolymer or a layer thereof.
Furthermore, a layer of a hydrophobic resin or a composition thereof is included, the layer of the polar group-modified polymer composition is laminated on the hydrophobic resin or a composition layer thereof, and the layer of the polar group-modified polymer composition is It is preferable to include a laminated unit in which the gas barrier layer is laminated.

  Even if the multilayer structure including the layer of the polar group-modified polymer composition of the present invention includes a layer whose characteristics deteriorate due to moisture absorption (moisture absorption layer), moisture absorption is not affected without affecting the appearance of the multilayer structure. It is possible to suppress deterioration in characteristics due to moisture absorption of the layer.

  Hereinafter, although it demonstrates in detail about the structure of this invention, these show an example of a desirable embodiment and are not specified by these content.

<Polar group-modified polymer composition>
The polar group-modified polymer composition of the present invention comprises (A) a polar group-modified polymer, and (B) a polar group-modified polymer containing a hydrate-forming alkaline earth metal salt having specific water absorption characteristics. It is a composition. Hereinafter, each component will be described.

[(A) Polar group-modified polymer]

  The polar group-modified polymer is a polymer in which a polymer having an aliphatic hydrocarbon monomer unit containing a carbon-carbon double bond is modified with a polar group-containing compound, and is a kind of thermoplastic resin. .

(1) Polar group-containing compound The polar group-containing compound refers to a compound having a polar group such as a carboxyl group, an amino group, an alkoxyl group, a hydroxyl group, an amide group, and an epoxy group. The carboxyl group includes an acid anhydride group that is a derivative of the carboxyl group.

  Examples of polar group-containing compounds used for carboxyl group modification include unsaturated carboxylic acids or derivatives thereof, and specifically, α, β-unsaturated carboxylic acids and α, β-unsaturated carboxylic acid anhydrides. More specifically, α, β-unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; α, β-unsaturated dicarboxylic acids such as maleic acid, succinic acid, itaconic acid, and phthalic acid; glycidyl acrylate Α, β-unsaturated monocarboxylic acid esters such as glycidyl methacrylate, hydroxyethyl acrylate and hydroxymethyl methacrylate; α, β-unsaturated dicarboxylic acid anhydrides such as maleic anhydride, succinic anhydride, itaconic anhydride and phthalic anhydride Things can be mentioned.

  Examples of the polar group-containing compound used for amino group modification include 3-lithio-1- [N, N-bis (trimethylsilyl)] aminopropane, 2-lithio-1- [N, N-bis (trimethylsilyl)]. Examples include aminoethane, 3-lithio-2,2-dimethyl-1- [N, N-bis (trimethylsilyl)] aminopropane, and specific examples of unsaturated amines or derivatives thereof include vinylamine.

  Examples of the polar group-containing compound used for the alkoxyl group modification include alkoxysilanes such as tetraethoxysilane, tetramethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, and dimethyldiphenoxysilane. Specific examples of the derivatives include alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, pentyl vinyl ether, and hexyl vinyl ether.

  Examples of the polar group-containing compound used for hydroxyl group modification include unsaturated alcohols or derivatives thereof, specifically 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol. Etc.

  Examples of the polar group-containing compound used for amide group modification include unsaturated amides or derivatives thereof. Specifically, N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylformamide, N- And polyoxyalkylene (meth) acrylamides such as methyl-N-vinylacetamide, diacetone acrylamide, acrylamide, methacrylamide, polyoxyethylene (meth) acrylamide, and polyoxypropylene (meth) acrylamide.

  Examples of polar group-containing compounds used for epoxy group modification include unsaturated epoxides or derivatives thereof, and specific examples include vinyl epoxides.

(2) “Polymer (p) having an aliphatic hydrocarbon monomer unit containing a carbon-carbon double bond” modified with a polar group-containing compound (may be abbreviated as “polymer (p)”)
The polymer (p) having an aliphatic hydrocarbon monomer unit containing a carbon-carbon double bond is an aliphatic hydrocarbon monomer containing at least a carbon-carbon double bond (hereinafter, unless otherwise specified, A polymer obtained by polymerizing "unsaturated aliphatic hydrocarbon compound" or "unsaturated aliphatic hydrocarbon monomer" refers to this "aliphatic hydrocarbon monomer containing a carbon-carbon double bond") The polymer (p) may contain monomer units other than the aliphatic hydrocarbon monomer containing a carbon-carbon double bond. The polymer (p) includes those classified as thermoplastic elastomers and ionomers.

As said unsaturated aliphatic hydrocarbon monomer, carbon-carbon double bond containing monomers, such as an olefin monomer and a diene monomer, are mentioned, for example.
Therefore, as the “polymer (p) having an aliphatic hydrocarbon monomer unit containing a carbon-carbon double bond”, for example, an olefin polymer mainly composed of the unsaturated aliphatic hydrocarbon monomer, and such And random copolymers and block copolymers of such olefin polymers and other monomers (for example, vinyl aromatic monomers). Specifically, a styrene thermoplastic elastomer (pS) or an olefin polymer (pO) is preferably used.

(2-1) Olefin polymer (pO)
The olefin polymer (pO) used for modification of the polar group-modified polymer is an olefin which is an aliphatic hydrocarbon monomer as a main monomer, and is usually a polymer having a molecular weight of 10,000 or more, and the main chain is composed of only carbon bonds. Refers to the lipophilic polymer that is composed. Specific examples include polyolefins, olefin-vinyl ester copolymers, olefin-based thermoplastic elastomers, olefin- (meth) acrylic acid ester copolymers, and ionomers.

The polyolefin refers to, for example, a homopolymer of olefin monomers such as ethylene, propylene, and butene, a random copolymer of two or more olefin monomers, and a block copolymer. Among them, examples of the olefin homopolymer include polyethylene such as ultra-low density polyethylene, (linear) low density polyethylene, and high density polyethylene, polypropylene, polybutene, polymethylpentene, and the like.
Examples of the olefin block copolymers include ethylene-α olefin block copolymers such as ethylene-propylene copolymers, ethylene-butene copolymers, ethylene-hexene copolymers, ethylene-octene copolymers; propylene-ethylene copolymers. Examples thereof include propylene-α olefin block copolymers such as polymers and propylene-butene copolymers; butene-α olefin block copolymers such as butene-ethylene copolymers and butene-propylene copolymers.
Specifically, the olefin random copolymer is a copolymer obtained by random copolymerization of two or more of the above olefin monomers. For example, ethylene-α olefin random copolymer, propylene-α olefin random copolymer, butene-α olefin. Examples thereof include two or more α-olefin random copolymers such as a random copolymer, and olefin-cyclic olefin copolymers such as ethylene-norbornene.

  As the cyclic olefin-based resin, known resins (for example, see JP-A No. 2003-103718, JP-A No. 5-17776, JP-A No. 2003-504523, etc.) can be used. The cyclic olefin-based resin has a low moisture permeability as compared with a chain aliphatic polyolefin such as polyethylene and polypropylene.

  Examples of the olefin-vinyl ester copolymer include ethylene-vinyl acetate copolymers having an ethylene content of 70 mol% or more, saponified products of ethylene-vinyl acetate copolymers having an ethylene content of 70 mol% or more. It is done.

  The olefinic thermoplastic elastomer is an elastomer that exhibits thermoplasticity using a polyolefin (such as polyethylene or polypropylene) as a hard segment and the aliphatic rubber (such as EPDM or EPM) as a soft segment. Examples thereof include those synthesized by a method of compounding rubber (compound type) or a method of introducing aliphatic rubber during olefin polymerization (reactor type). The compound type includes a simple blend product (non-crosslinked type) and a dynamic crosslinked product (two types of full-crosslink type or partial crosslink type).

  Examples of the olefin- (meth) acrylic acid ester copolymer include an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-methyl methacrylate copolymer.

  The ionomer resin is a metal salt of an ethylene-unsaturated carboxylic acid copolymer, and the carboxyl group in the resin is neutralized with a metal.

  Among these, from the viewpoint of thermal stability, polyethylene, polypropylene, ethylene-α olefin block copolymer, propylene-α olefin block copolymer, ethylene-α olefin random copolymer, propylene-α olefin random copolymer , Ethylene-vinyl acetate copolymer is preferred, and when hot water resistance and moisture resistance are important, aliphatic polyolefins such as polypropylene, propylene-α olefin block copolymer, propylene-α olefin random copolymer, Cyclic polyolefins are preferred.

(2-2) Styrenic thermoplastic elastomer (pS)
Styrenic thermoplastic elastomer (pS) is a polymer block of a vinyl aromatic monomer that is usually a hard segment (hereinafter sometimes referred to as “aromatic vinyl polymer block”) (b1), and a non-polymer that is usually a soft segment. It has a polymer block obtained by polymerizing a saturated aliphatic hydrocarbon monomer (hereinafter sometimes referred to as “aliphatic hydrocarbon polymer block”) and / or its hydrogenated block (b2).

  The styrenic thermoplastic elastomer (pS) only needs to contain the aromatic vinyl polymer block (b1), the aliphatic hydrocarbon polymer block and / or its hydrogenated block (b2). What can be obtained as a plastic elastomer can be used. The combination of the polymer blocks b1 and b2 is not particularly limited, and a diblock structure represented by b1-b2, a triblock structure represented by b1-b2-b1 or b2-b1-b2, b1-b2 It may be a tetrablock structure represented by -b1-b2 or a polyblock structure in which b1 and b2 are linearly bonded. Among these, the diblock structure represented by b1-b2, the triblock structure represented by b1-b2-b1, and the tetrablock structure represented by b1-b2-b1-b2 have flexibility and mechanical properties. It is preferable from the point.

  Specific examples of the monomer (vinyl aromatic monomer) constituting the aromatic vinyl polymer block (b1) include styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, and m-methylstyrene. Styrene derivatives such as p-methylstyrene, t-butylstyrene, 2,4-dimethylstyrene, 2,4,6-trimethylstyrene, monofluorostyrene, difluorostyrene, monochlorostyrene, dichlorostyrene, methoxystyrene; vinyl naphthalene, Examples thereof include vinyl aromatic compounds such as vinyl anthracene, indene, and acetonaphthylene. Furthermore, if necessary, other copolymerizable monomers such as 1-butene, pentene, hexene, butadiene, isoprene, and methyl vinyl ether may be used together with these vinyl aromatic monomers.

  Of the vinyl aromatic monomers as described above, styrene and styrene derivatives are preferable, and styrene is more preferably used.

The aromatic vinyl polymer block (b1) may be a homopolymer block of the above vinyl aromatic monomer or a copolymer block of two or more vinyl aromatic monomers.
Further, when the aromatic vinyl polymer block (b1) contains another copolymerizable monomer, the content of the other copolymerizable monomer in the aromatic vinyl polymer block (b1) is expressed as styrene-based thermoplastic elastomer (pS). In order not to impair the elastomeric property of the polymer block (b1), the content is preferably 10% by weight or less, more preferably 5% by weight or less.

  As an unsaturated aliphatic hydrocarbon monomer which comprises the said aliphatic hydrocarbon polymer block (b2), it is a C2-C10 unsaturated aliphatic hydrocarbon compound normally, Specifically, C2-C2 6 alkene, C 4-6 diene, and conjugated diene are mentioned. Among these, C 4-6 conjugated diene is preferably used.

  Examples of the conjugated diene compound include isoprene, butadiene, hexadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and the like. Examples of the diene include hexanediene. The aliphatic hydrocarbon polymer block (b2) made of a diene compound may be obtained as a result of hydrogenation of the polymer block made of the conjugated diene compound. Examples of the alkene include ethylene, propylene, n-butylene, and isobutylene. The aliphatic hydrocarbon polymer block (b2) composed of these alkenes may be obtained as a result of hydrogenation of the polymer block composed of the conjugated diene or diene.

  The aliphatic hydrocarbon polymer block (b2) may be a homopolymer block composed of one of the above unsaturated aliphatic hydrocarbon monomers, or a random copolymer block composed of two or more unsaturated aliphatic hydrocarbon monomers. It may be. The soft segment is preferably a polymer block of conjugated diene or a hydrogenated block thereof.

  The hydrogenated block of the aliphatic hydrocarbon polymer block is formed by hydrogenation of a part or all of unsaturated bonds in the polymer block of diene and / or conjugated diene. For example, a polybutadiene block becomes an ethylene / butylene polymer block or a butadiene / butylene polymer block by hydrogenation. The polyisoprene block becomes an ethylene / propylene polymer block or the like by hydrogenation. Hydrogenation can be performed by a known method. Hydrogenation may also be performed selectively on specific vinyl binding moieties.

  The styrenic thermoplastic elastomer (pS) is a combination of the aromatic vinyl polymer block (b1) and the unsaturated aliphatic hydrocarbon polymer block or its hydrogenated block (b2). Without limitation, for example, a radial teleblock copolymer, a multiblock copolymer, a bimodal copolymer, a tapered block copolymer and the like can be mentioned.

  The content of the aromatic vinyl polymer block (b1) in the styrenic thermoplastic elastomer (pS) is usually 5 to 50% by weight, preferably 10 to 40% by weight, more preferably 10 to 35% by weight, and still more preferably. Is 15 to 35% by weight. When the content rate of a polymer block (b1) is too large, there exists a tendency for the softness | flexibility of styrene-type thermoplastic elastomer (pS) itself to fall. When the content rate of a polymer block (b1) is too small, there exists a tendency for the transparency of a film to fall.

  The content of the aliphatic hydrocarbon polymer block and / or its hydrogenated block (b2) in the styrene-based thermoplastic elastomer (pS) is usually 50 to 95% by weight, preferably 60 to 90% by weight, More preferably, it is 65 to 90% by weight.

  Specific examples of the styrenic thermoplastic elastomer (pS) having the above-described configuration include, for example, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), and SBS. Hydrogenated block copolymer (SEBS), SIS hydrogenated block copolymer (SEPS), block copolymer (SBBS) obtained by hydrogenating the vinyl bond portion of the butadiene block of SBS, styrene-isobutylene-styrene triblock A copolymer (SIBS), a styrene-ethylene-butylene-crystalline polyolefin block copolymer (SEBC), etc. are mentioned. Among these, SEBS which is excellent in thermal stability and weather resistance is preferably used. In SEBS, a polybutadiene block is converted to an ethylene / butylene copolymer block by hydrogenation.

  Further, the polymer blocks (b1) and (b2) may be random copolymer blocks containing other copolymerizable monomers as necessary. However, when other copolymerizable monomer is included, the content of the other copolymerizable monomer in each polymer block is preferably 10% by weight or less of each polymer block weight, and may be 5% by weight or less. More preferred.

(3) Constitution of polar group-modified polymer The synthesis of the polar group-modified polymer, that is, the modification of the polymer (pO or pS) with the polar group-containing compound is carried out by using the constituent monomer of the polymer (pO or pS). A method in which a part of the group is copolymerized instead of a polar group-containing compound, a method in which a polar group-containing compound is introduced into a part of the side chain by radical addition, or an aliphatic hydrocarbon monomer unit containing a carbon-carbon double bond It is performed by a method of post-modifying a polymer having

The content of the polar group derived from the polar group-containing compound in the polar group-modified polymer is usually 0.1 × 10 ⁻³ to 1 mmol / g, preferably 0.5 × 10 ^{−3 to} 0.5 mmol / g, More preferably, it is 1 * 10 ^<-2 > -0.2 mmol / g, More preferably, it is 1 * 10 ^{< -2} > -0.1 mmol / g. If the polar group content is too large, the reactivity with a hydrophilic resin such as EVOH resin is too strong and tends to cause poor appearance due to rough adhesion at the time of coextrusion. If the polar group content is too low, the adhesive strength with a hydrophilic resin such as EVOH resin tends to decrease.

When the polar group-modified polymer is a carboxyl group-modified styrene-based thermoplastic elastomer, the content of the carboxyl group has an acid value measured by titration is usually less than 20mgCH ₃ ONa / g, preferably 1~15mgCH ₃ ONa / g, more preferably 1~5mgCH ₃ ONa / g.
If the acid value is too high, the reactivity with a hydrophilic resin such as EVOH resin is too strong and tends to cause poor appearance due to rough adhesion at the time of coextrusion. If the acid value is too small, the adhesive strength with a hydrophilic resin such as EVOH resin tends to be reduced.

  The melt flow rate (MFR) of the polar group-modified styrene thermoplastic elastomer is usually 0.01 to 200 g / 10 minutes, preferably 0.1 to 100 g / 10 minutes, at 230 ° C. and a load of 2160 g. More preferably, it is 1-50 g / 10min, Most preferably, it is 2-15g / 10min.

  A commercially available product may be used as such a polar group-modified styrene-based thermoplastic elastomer. Examples of commercially available polar group-modified styrenic thermoplastic elastomers include “Tough Tech” M series manufactured by Asahi Kasei Co., Ltd., “Kraton” FG series manufactured by Kraton Polymer, and “f-Dynalon” series manufactured by JSR.

  As the preferred polar group-modified polymer when the polymer (p) is an olefin polymer, typically, an unsaturated carboxylic acid or its anhydride is chemically bonded to the olefin resin by an addition reaction or a graft reaction. And a carboxyl group-modified olefin polymer obtained in the above manner. For example, maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-propylene (block and random) copolymer, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft Modified ethylene-vinyl acetate copolymer, maleic anhydride-modified cyclic olefin resin, maleic anhydride graft-modified olefin resin, and the like.

  In the case of a carboxyl group-modified olefin polymer, the content (modified amount) of the carboxyl group is usually 0.01 to 10% by weight, preferably 0.01 to 5% by weight of the olefin polymer as the polymer (p). %, More preferably 0.1 to 2% by weight, particularly preferably 0.2 to 1% by weight. If the amount of modification is too small, the adhesive strength with a hydrophilic resin such as EVOH resin tends to decrease. On the other hand, if the amount is too large, the reactivity with a hydrophilic resin such as EVOH resin is too strong and tends to cause poor appearance due to rough adhesion at the time of coextrusion.

  The melt flow rate (MFR) of the polar group-modified olefin polymer is usually 0.01 to 150 g / 10 min, preferably 0.1 to 50 g / 10 min under the conditions of 210 ° C. and a load of 2160 g, and more Preferably it is 1-25 g / 10min, Most preferably, it is 1.5-10g / 10min. Moreover, it is 0.01-200 g / 10min normally on 230 degreeC and load 2160g conditions, Preferably it is 1-35 g / 10min, Especially preferably, it is 2-15 g / 10min.

  As such a polar group-modified olefin polymer, a commercially available product may be used. Commercially available polar group-modified olefin polymers include, for example, “Admer”, “Tafmer” M series (Mitsui Chemicals), “Biner”, “Fusabond” (DuPont), “Orevac” (Arkema) ), “Plexer” (manufactured by Equistar), and “Modic AP” (manufactured by Mitsubishi Chemical Corporation).

The above polar group-modified polymers may be used alone or in combination of two or more.
Further, the resin is not limited to the virgin resin, and may be a recycled resin including a plurality of types of thermoplastic resins.

  Such a polar group-modified polymer is appropriately selected according to the required use. When used in a multilayer structure in which other resin layers are laminated, it is appropriately selected according to the type of other resin layers to be combined. The polar group-modified polymer generally has a role of increasing the bonding strength between the hydrophobic resin and the resin having a polar group, and the polar group-modified polymer of the present invention functions to improve the moisture resistance of other resin layers. Therefore, it can be preferably used as an adhesive resin layer used between a resin layer having a polar group and a hydrophobic resin layer whose characteristics tend to be reduced by moisture absorption.

  In particular, in a multilayer structure using a vinyl alcohol resin layer such as EVOH resin as a gas barrier layer in combination with a hydrophobic resin layer for strength enhancement, surface protection, etc., the vinyl alcohol resin layer and the hydrophobic structure are used. It is preferable to use it as an adhesive resin layer interposed between the resin layer. In such applications, modification with a carboxyl group- or amino group-containing compound is preferred, and modification with a carboxyl group-containing compound is more preferred.

[(B) Hydrate-forming alkaline earth metal salt]
The hydrate-forming alkaline earth metal salt (B) used in the present invention is an alkaline earth metal salt having a property of taking water molecules as crystal water, and has the following water absorption characteristics (α), preferably Furthermore, (β) and / or (γ) is satisfied.

Water absorption property (α): When the hydrate-forming alkaline earth metal salt (B) used is left at 40 ° C. and 90% relative humidity with respect to the crystallization water content (Y) in the maximum hydrate. The ratio (X ₅ / Y) of water absorption (X ₅ ) per 100 g of the alkaline earth metal salt (B) for 5 days is 0.2 to 2.0, preferably 0.5 to 2.0, More preferably, it is 0.75-2.0.

The maximum hydrate refers to a hydrate containing crystal water at the maximum hydration number, and the crystal water content (Y) is a hydrate in an anhydrous state not including crystal water. The amount (unit: g) of crystal water that can be taken in by 100 g of the substance-forming alkaline earth metal salt (B). Such crystal water content (Y) is a value determined by the following formula, and is a value specific to the type of alkaline earth metal salt.
Y (g) = [(Hydration number of maximum hydrate × 18) / (Molecular weight of anhydride)] × 100

For example, when calcium lactate (C ₆ H ₁₀ CaO ₆ : molecular weight 218) is used as the hydrate-forming alkaline earth metal salt (B), the maximum hydrate of calcium lactate is pentahydrate. Therefore, Y = 41 g is obtained by the following calculation.
Y = [(5 × 18) / 218] × 100 = about 41

The crystal water content (Y) in the maximum hydrate corresponds to the water content when the hydrate-forming alkaline earth metal salt (B) is present as the maximum hydrate. The alkaline earth metal salt (anhydride) used as a component is an index of the maximum amount that can absorb water, and is an index related to the amount of moisture trapped in the polar group-modified polymer (A). Y is large because it is considered that moisture absorption by other resin layers having hygroscopicity is suppressed in the case of a multilayer structure as the amount of moisture trapped in the polar group-modified polymer (A) increases. The more preferable. Therefore, Y preferably satisfies 30 g or more, more preferably 40 g or more, and particularly preferably 50 g or more.
On the other hand, the hydrate-forming alkaline earth metal salt (B) is not necessarily the most stable hydrate. The number of water of crystallization contained in the most stable hydrate (stable hydrate) may be less than the maximum hydrate. For example, in trimagnesium dicitrate, the most stable hydrate is 9 hydrate, but the maximum hydrate is 14 hydrate.

Water absorption per 100 g of the alkaline earth metal salt (B) for 5 days when the hydrate-forming alkaline earth metal salt (B) used is left at 40 ° C. and 90% relative humidity. (X ₅ ) is the water absorption after 100 g of the target hydrate-forming alkaline earth metal salt (B) dehydrate (anhydride) is left at 40 ° C. and 90% relative humidity for 5 days. It is an amount (unit: g), and is obtained by the following formula.
X ₅ = [(5 days water absorption) / (initial weight)] × 100
The amount of water absorption for 5 days can be calculated from (weight after standing 5 days-initial weight).

The “initial weight” in the formula refers to the weight before use of the metal salt actually used.
“Initial weight” and “weight after 5 days” are both actual measured values, and can be measured using a weight measuring device such as an electronic balance. The value varies depending not only on the type of the alkaline earth metal salt compound, but also on the production method of the compound, the presence or absence of contained crystal water, and the properties.
In addition, when an hydrate-forming alkaline earth metal salt anhydride is used as the component (B), the water content should theoretically be 0 g, but the initial weight used here is, for example, thermal weight Using a measuring device (Perkin Elmer's thermogravimetric measuring device “Pyris 1 TGA”), the weight is in an equilibrium state (completely dehydrated state). Weight.

The water absorption (X ₅ ) is usually 10 to 200 g, preferably 20 to 100 g, particularly preferably 30 to 75 g. Alkaline earth metal salts with a large amount of water absorption (X ₅ ) tend to take in water that exceeds the amount that forms stable hydrates, so the appearance is poor when the multilayer structure is left under high humidity conditions. Tend to occur. On the other hand, since the alkaline earth metal salt having a small water absorption amount (X ₅ ) has a small trapping capacity for moisture that has entered the polar group-modified polymer (A), the heat in the multilayer structure having a gas barrier layer can be reduced. The gas barrier properties after water treatment (retort treatment) tend to be insufficient.

The ratio (X ₅ / Y) of the water absorption amount (X ₅ ) to the crystal water content (Y) defined as described above indicates that the hydrate-forming alkaline earth metal salt (B) is stable. The ratio of the amount of water that is absorbed in 5 days to the amount of water that can be trapped is shown as an index for appearance failure when the multilayer structure is left under high humidity conditions. That is, an alkaline earth metal salt having a value of X ₅ / Y within the above range has an appropriate water absorption capacity and does not absorb water excessively. On the other hand, if X ₅ / Y is too large, the hydrate-forming alkaline earth metal salt (B) takes in more water than can stably absorb water, and excessive water absorption causes poor appearance in the multilayer structure. It's easy to do. On the other hand, when X ₅ / Y is too small, the ability to capture moisture that has entered the polar group-modified polymer (A) is small, and in the multilayer structure, moisture absorption is performed by another resin layer having high moisture absorption as a result. Will be.

Water absorption property (β): The amount of water absorption (Z) per 100 g after 24 hours when the alkaline earth metal salt (B) is left at 40 ° C. and 90% relative humidity is preferably 10 g or more. More preferably, it is 30 g or more, More preferably, it is 50 g or more.
Z is expressed as the amount of water absorption (g) when 100 g of the hydrate-forming alkaline earth metal salt (B) used is left at 40 ° C. and 90% relative humidity for 24 hours.
If the amount of water absorption (Z) is too small, the trapping rate of water entering the polar group-modified polymer (A) is small, and in the multilayer structure, as a result, the moisture absorption tends to be absorbed by another resin layer. There is.

  Water absorption characteristics (γ): It has a maximum point of water absorption when left at 40 ° C. and 90% relative humidity.

The maximum point of water absorption refers to a case where the weight after water absorption starts to decrease in a change in water absorption for 6 days when left at high temperature and high humidity (for example, 40 ° C. and 90% relative humidity).
Specifically, the amount of water absorption measured in units of 24 hours (X, the amount of water absorption after n days is X _n ) is further less than the amount of water absorption (X _{n + 1} ) after 24 hours (n + 1 days later). If you are. Here, the “water absorption amount” on the nth day is calculated by (weight after n days−initial weight).
Therefore, it can be said that the water absorption property (γ) is a property of releasing a part of the absorbed water after the water absorption amount reaches the maximum, and excessive water absorption is suppressed after the compound absorbs a predetermined amount of water. Means that. Therefore, it is possible to avoid the hydrate-forming alkaline earth metal salt (B) from being dissolved by water absorbed by itself. In addition, if there is a stable hydrate with a lower hydration number than the maximum hydrate, it is considered that the water content is adjusted so that the water reaches the maximum hydrate and then approaches the stable hydrate. It is done.

  The hydrate-forming alkaline earth metal salt (B) that satisfies the water absorption characteristics as described above captures moisture that has entered the polar group-modified polymer (A) and constitutes a multilayer structure. It is possible to suppress deterioration in characteristics due to moisture absorption of the resin layer. Moreover, even if exposed to a high temperature and high humidity environment for a long period of time, excessive water that has been trapped again is avoided so that excessive water absorption exceeding the trapping capacity can be avoided, or even after having absorbed excessive water, it can exist as a stable hydrate. By releasing, it is possible to provide a multilayer structure that can suppress poor appearance and maintain an excellent appearance.

  Examples of the hydrate-forming alkaline earth metal salt (B) that can satisfy the water absorption properties as described above include lactate (calcium lactate [pentahydrate]), citrate (calcium citrate [calcium citrate [ Tetrahydrate], trimagnesium dicitrate [14 hydrate], magnesium hydrogen citrate [pentahydrate]) and the like, silicates (magnesium silicate [pentahydrate]), phosphorus Examples thereof include acid salts (trimagnesium phosphate [octahydrate]), carbonates (basic magnesium carbonate [pentahydrate]), and the like. [] Shows the maximum hydration number of the maximum hydrate. These hydrate-forming alkaline earth metal salts (B) may be used alone or in admixture of two or more.

  The hydrate-forming alkaline earth metal salt (B) used in the present invention is an alkaline earth metal salt whose stable hydrate is usually 1 to 20 hydrate, preferably 3 to 18 hydrate. An alkaline earth metal salt that becomes a product, particularly preferably an alkaline earth metal salt that becomes a 5 to 15 hydrate. When the content of water of crystallization contained in the stable hydrate is small, the trapping ability of entering water tends to be small.

  Such an alkaline earth metal salt (B) maximum hydrate anhydride (when water of crystallization is 0) or partial hydrate (metal salt containing water of crystallization less than the hydration number of stable hydrate) ) Is used as a desiccant. In the case of partially dehydrated (or partially hydrated), in general, if the amount of water of crystallization is less than 50% of the maximum hydrated amount (preferably 30% or less, more preferably 10% or less), There exists a tendency which can satisfy the said water absorption characteristic.

  The hydrate-forming alkaline earth metal salt (B) anhydride or partial hydrate may be produced by completely or partially dehydrating the hydrate, or may be a commercially available anhydride or Partial hydrate crystals may be used. In short, any hydrate-forming alkaline earth metal salt that satisfies the above-mentioned water-absorbing property (α) may be used, preferably at least one of the water-absorbing properties (β) and (γ) described above. Is preferably satisfied.

  The water content of the hydrate-forming alkaline earth metal salt (B), the anhydride (completely dehydrated) or the partially hydrated (partially dehydrated) compound, is the theoretical amount calculated from the chemical formula. Does not necessarily match. For example, in the case of anhydride (completely dehydrated), the water content based on crystal water is theoretically 0, so the water content measured with a thermogravimetric apparatus should also be 0% by weight. However, the measured value may exceed 0% by weight due to moisture absorption or the like. For example, in the case of a completely dehydrated trimagnesium dicitrate, the value measured by the thermogravimetric apparatus is about 0 to 10% by weight. Although these are considered to be due to moisture absorption, even when moisture is absorbed, the value measured by the thermogravimetric apparatus is preferably 0 to 5% by weight as a completely dehydrated product.

  The actual water content can be measured by using, for example, a thermogravimetric measurement device (manufactured by Perkin Elmer, thermogravimetric measurement device “Pyris 1 TGA”). The moisture content as a measured value is the ratio of the moisture content to the whole compound, and is a value calculated by the moisture content (moisture content) contained when the weight equilibrium is reached from the start of measurement.

  Among the alkaline earth metal salts (B), from the viewpoint of hygroscopicity, calcium carbonate, magnesium silicate, trimagnesium phosphate, and completely dehydrated alkaline earth metal salts of citric acid are preferably used. Further, a completely dehydrated product of an alkaline earth metal salt of citric acid, particularly a magnesium salt such as trimagnesium dicitrate is preferable from the viewpoint of satisfying the water absorption property (γ) and suppressing excessive moisture absorption.

  The hydrate-forming alkaline earth metal salt (B) is usually a powder. The particle distribution is a value measured based on PSTM E11-04. Usually, 120 mesh pass is 50% by volume or more, preferably 120 mesh pass is 80% by volume or more, particularly preferably 120 mesh pass is 95% by volume. That's it. It is preferable that the particle distribution has a large particle ratio of 120 mesh pass from the viewpoint of good dispersibility in the polar group-modified polymer (A). When the particle ratio of the 120 mesh pass is too small, the appearance characteristics of the multilayer structure tend to deteriorate.

  The hydrate-forming alkaline earth metal salt (B) having the properties described above has an ability to suppress excessive moisture absorption under high temperature and high humidity while maintaining high water absorption capability. Therefore, a layer of a resin composition in which such a hydrate-forming alkaline earth metal salt (B) is blended with the polar group-modified polymer (A) and a highly hygroscopic resin layer (for example, an EVOH resin) When the multilayer structure including the gas barrier layer) is left under high temperature and high humidity, the resin composition layer absorbs moisture preferentially over the resin layer with high hygroscopicity, so that the resin layer with high hygroscopic property can be obtained. Defects due to moisture absorption (deterioration of function, poor appearance, etc.) can be suppressed. Moreover, since the resin composition layer of the present invention does not have a particular change in appearance and deterioration of properties due to moisture absorption, it is possible to realize moisture resistance imparting to the entire multilayer structure.

In the present invention, it is preferable that a hydrate-forming alkaline earth metal salt (B) is dispersed in the polar group-modified polymer (A).
Therefore, in the resin composition of the present invention, the content weight ratio (A / B) of the polar group-modified polymer (A) / hydrate-forming alkaline earth metal salt (anhydride) (B) is usually 50. Super / less than 50 to 99/1 (over 50/50 to 99/1 or less), more preferably 70/30 to 97/3, particularly 85/15 to 92/8. When this ratio is too large, the effect of removing moisture that has entered the polar group-modified polymer (A) is lowered, and the moisture resistance imparting effect tends to be lowered. On the other hand, when it is too small, it means that the content of the alkaline earth metal salt is large with respect to the polar group-modified polymer (A), and the fluidity of the resin composition is lowered, and as a result, the extrusion moldability is low. It tends to decrease.

[(C) Additive]
In addition to the components (A) and (B), the polar group-modified polymer composition of the present invention may contain the following compounds as necessary.
The content of the following additives in the resin composition is within a range that does not impair the effects of the present invention, specifically, the total amount of the additive is usually 30% by weight or less, preferably 10% by weight or less. is there.

(C-1) Other thermoplastic resins A range of thermoplastic resins other than the polar group-modified polymer (A) ("other thermoplastic resins") that do not affect the properties of the polar group-modified polymer, specifically Specifically, it may be contained in an amount of usually 30% by weight or less, preferably 10% by weight or less based on the polar group-modified polymer (A).

  As the other thermoplastic resin, specifically, linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, Ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, ethylene-acrylate copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer Olefin homo- or copolymers such as polybutene and polypentene, olefin-based resins in a broad sense such as polycyclic olefin, polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid ( Nylon 9), polyundecanamide (nylon 11), polylauryl lactam ( Polyamide resins such as Iron 12), copolymer polyamide resins such as caprolactam / lauryl lactam copolymer (nylon 6/12), caprolactam / hexamethylene diammonium adipate copolymer (nylon 6/66), polystyrene resins, polyesters Resin, polyvinyl chloride, polyvinylidene chloride, acrylic resin, vinyl ester resin, polyester elastomer, polyurethane elastomer, polystyrene elastomer, chlorinated polyethylene, chlorinated polypropylene, saponified ethylene-vinyl acetate copolymer ( EVOH resin) and the like.

(C-2) Dispersant The polar modified polymer composition of the present invention further comprises a dispersant in order to enhance the dispersibility of the alkaline earth metal salt (B) in the polar group-modified polymer (A). It is preferable to contain. Examples of such a dispersant include dispersants conventionally used in resin compositions, such as higher fatty acids (for example, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid metal salts ( Aluminum salts of higher fatty acids such as stearic acid, calcium salts, zinc salts, magnesium salts, barium salts, etc.), higher fatty acid esters (such as glycerin esters, methyl esters, isopropyl esters, butyl esters, octyl esters of higher fatty acids), higher fatty acids Amides (saturated fatty acid amides such as stearic acid amide and behenic acid amide, unsaturated fatty acid amides such as oleic acid amide, erucic acid amide, ethylene bisstearic acid amide, ethylene bis oleic acid amide, ethylene biserucic acid amide, ethylene bis laurin Acid Bis fatty acid amides), low molecular weight polyolefins (for example, low molecular weight polyethylene having a molecular weight of about 500 to 10,000, or low molecular weight polypropylene, or acid-modified products thereof), higher alcohols, ester oligomers, fluorinated ethylene resins, and the like. It is done.
Among these dispersants, when importance is placed on the suppression of phase-separated foreign matter, higher fatty acid alkaline earth metal salts and transition metal salts having 12 to 20 carbon atoms are preferred, and stearic acid, hydroxystearic acid, oleic acid are particularly preferred. Calcium salt, magnesium salt and zinc salt of lauric acid are preferred.

  The blending amount of such a dispersant is preferably 0.00001 to 5% by weight in the composition, more preferably 0.0001 to 2.5% by weight, still more preferably 0.001. 001 to 1% by weight.

(C-3) Plate-like inorganic filler As the plate-like inorganic filler, for example, kaolin containing hydrous aluminum silicate as a main component and particles are plate-like, layered silicate mineral mica or smectite, hydroxylation Examples include talc composed of magnesium and silicate. Of these, kaolin is preferably used. The type of kaolin is not particularly limited and may or may not be calcined, but calcined kaolin is preferred.

  These plate-like inorganic fillers have a function of preventing moisture permeation. In particular, in the case of film forming, since the plate-like surface of the plate-like filler is easily oriented in the plane direction of the film, it is considered that the plate-like inorganic filler oriented in the plane direction can contribute to blocking moisture permeation of the composition layer. It is done. Therefore, in the multilayer structure, the polar group-modified polymer composition layer of the present invention is disposed closer to the surface layer than the highly hygroscopic resin layer (hygroscopic layer), thereby reducing the characteristics of the hygroscopic layer due to moisture absorption. Can be suppressed. That is, it is possible to further enhance the moisture resistance imparting effect of the polar group-modified polymer composition of the present invention.

  The addition amount of such a plate-like inorganic filler is usually 1 to 20% by weight, preferably 3 to 20% by weight, and more preferably 5 to 15% by weight with respect to the polar group-modified polymer (A). %.

(C-4) Oxygen Absorber In order to impart an oxygen barrier function to the polar group-modified polymer composition of the present invention, an oxygen absorbent may be further contained.
An oxygen absorber is a compound or compound system that captures oxygen more quickly than the contents to be packaged. Specific examples include an inorganic oxygen absorbent, an organic oxygen absorbent, and a composite oxygen absorbent using a combination of an inorganic catalyst and an organic compound.

Examples of the inorganic oxygen absorbent include metals and metal compounds, which absorb oxygen when they react with oxygen. As the metal, a metal (Fe, Zn, Mg, Al, K, Ca, Ni, Sn, etc.) having a higher ionization tendency than hydrogen is preferable, and typically iron. These metals are preferably used in powder form. As the iron powder, any conventionally known iron powder, such as reduced iron powder, atomized iron powder, electrolytic iron powder, etc., can be used without particular limitation. Moreover, the iron used may be obtained by reducing iron once oxidized. The metal compound is preferably an oxygen deficient metal compound. Here, examples of the oxygen-deficient metal compound include cerium oxide (CeO ₂ ), titanium oxide (TiO ₂ ), and zinc oxide (ZnO). These oxides are reduced from the crystal lattice by reduction treatment. It is pulled out to be in an oxygen deficient state and exhibits oxygen absorbing ability by reacting with oxygen in the atmosphere. The metals and metal compounds as described above preferably contain a metal halide or the like as a reaction accelerator.

  Examples of the organic oxygen absorbent include a hydroxyl group-containing compound, a quinone compound, a double bond-containing compound, and an oxidizable resin. Oxygen can be absorbed when oxygen reacts with a hydroxyl group or a double bond contained therein. As the organic oxygen absorber, ring-opening polymers of cycloalkenes such as polyoctenylene, conjugated diene polymers such as butadiene, and cyclized products thereof are preferable.

  The composite oxygen absorber refers to a combination of a transition metal catalyst and an organic compound, which excites oxygen by the transition metal catalyst and absorbs oxygen by the reaction between the organic compound and oxygen. Oxygen can be captured and absorbed by the organic compound in the composite oxygen absorbent reacting with oxygen earlier than the food or the like as the contents of the package. The transition metal constituting the transition metal catalyst is, for example, at least one selected from titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, ruthenium, and palladium. Cobalt is preferable in terms of solubility, functionality as a catalyst, and safety. The organic compound is preferably a ring-opening polymer of a cycloalkene such as polyoctenylene, which is an organic oxygen absorbent, a conjugated diene polymer such as butadiene, and a cyclized product thereof. Examples of other organic compounds include MXD nylon and the like. Preferred are nitrogen-containing resins, tertiary hydrogen-containing resins such as polypropylene, polyalkylene ether bond-containing resins such as block copolymers having polyalkylene ether units, and anthraquinone polymers.

  Further, the content ratio (mass ratio) between the transition metal catalyst and the organic compound is preferably 0.0001 to 5% by weight, more preferably 0.0005 to 1% by weight in terms of metal element, based on the mass of the organic compound. %, More preferably 0.001 to 0.5% by weight.

(C-5) Other additives In the resin composition of the present invention, in addition to the above, if necessary, the effects of the present invention are not impaired (for example, less than 5% by weight of the entire resin composition). Plasticizers such as aliphatic polyhydric alcohols such as ethylene glycol, glycerin and hexanediol; saturated aliphatic amides (eg stearic acid amides), unsaturated fatty acid amides (eg oleic acid amides), bis fatty acid amides (eg ethylene Bisstearic acid amide), low molecular weight polyolefin (for example, low molecular weight polyethylene having a molecular weight of about 500 to 10,000, or low molecular weight polypropylene), etc .; antiblocking agent; antioxidant; coloring agent; antistatic agent; Antibacterial agent; insoluble inorganic salt (for example, hydrotalcite); filler (for example, inorganic filler) Known additives such as surfactants, waxes, conjugated polyene compounds, enediol group-containing substances (eg, phenols such as propyl gallate), aldehyde compounds (eg, unsaturated aldehydes such as crotonaldehyde) Can be contained appropriately.
Among these additives, when emphasis is placed on the suppression of the phase separation foreign matter, the hydrotalcite represented by the formula (H1) and the formula (H2) is 0.00001 to 1 weight with respect to 100 parts by weight of the composition. It is preferable to contain in the range of part, and it is particularly preferable to blend the hydrotalcite-based solid solution represented by the formula (H2).

_{M x Al y (OH) 2x} + 3y-2z (E) z · aH 2 O ...... (H1)
[Wherein, M is Mg, Ca or Zn, E is CO ₃ or HPO ₄ , x, y and z are positive numbers, and a is 0 or a positive number. ]

^{_{[(M 1 2+) y1 (}} M 2 2+) y2] 1-x M x 3+ (OH) 2 A n- x / n · mH 2 O ...... (H2)
[Wherein M ₁ ²⁺ is at least one metal selected from Mg, CpSr and Ba, M ₂ ²⁺ is at least one metal selected from Zn, Cd, Pb and Sn, and M _x ³⁺ is Trivalent metal, A ⁿ⁻ is an n-valent anion, x, y ₁ , y ₂ , and m are 0 <x ≦ 0.5, 0.5 <y ₁ <1, y ₁ + y ₂ = 1, 0 ≦, respectively. It is a positive number represented by m <2. ]

<Method for Preparing Polar Group-Modified Polymer Composition>
In mixing the polar group-modified polymer (A) and the hydrate-forming alkaline earth metal salt (B), usually a melt kneading method or a mechanical mixing method (pellet dry blend) is performed, preferably It is a melt-kneading method. Specifically, a method of melt-mixing each component after dry blending, or a method of mixing a hydrate-forming alkaline earth metal salt (B) with the molten polar group-modified polymer (A) can be mentioned. .

  The polar group-modified polymer composition of the present invention may be subjected to molding as it is to obtain various molded products, or once, a high concentration of partially dehydrated or completely dehydrated alkaline earth metal salt hydrate. A composition (also referred to as a master batch) may be manufactured and diluted with the polar group-modified polymer (A) during molding to obtain various molded products. The weight ratio (A / B) of the polar group-modified polymer (A) and the hydrate-forming alkaline earth metal salt (B) in such a masterbatch is usually from 10/90 to less than 50/50. .

  Mixing order is, for example, (1) Method of blending (A) component and (B) component at the same time; (2) First, (B) component is blended excessively with (A) component, and (B) component high concentration composition After manufacturing a product, there is a method in which the polar group-modified polymer (A) is added to this high-concentration composition to dilute the component (B) to obtain a desired composition. When the component (C) is contained, it may be blended simultaneously with the component (A) and the component (B), or may be preliminarily contained in the component (A), or the component (A) and the component (B). Component (C) may be added to the blend of components.

  Normally, the method (1) is used, but from the viewpoint of cost during distribution, a high concentration composition of the component (B) is once manufactured and used after being diluted at the time of molding as in the method (2). A method is also preferably employed. At this time, the content weight ratio (A / masterbatch) of the polar group-modified polymer (A) with respect to the masterbatch is usually 10/90 to 99/1, depending on the composition of the masterbatch, preferably 20 / 80 to 95/5, particularly preferably 30/70 to 90/10.

  As the mixing method, any blending method such as a dry blending method using a Banbury mixer or the like, a melt kneading method using a single or twin screw extruder, and pelletizing can be adopted. Such melt kneading temperature is usually 150 to 300 ° C, preferably 170 to 250 ° C.

The polar group-modified polymer (A) is impregnated with the component (B) by immersing the polar group-modified polymer (A) in an aqueous solution of a hydrate-forming alkaline earth metal salt (B). It is also possible to employ a method (impregnation method) for producing by drying and then drying. However, this impregnation method is difficult to employ because it tends to reduce the hydrate-forming ability of the hydrate-forming alkaline earth metal salt (B) in the molded product obtained by molding the resin composition.
In addition, the stable hydrate of the alkaline earth metal salt (B) is mixed with the polar group-modified polymer (A) and melt-kneaded, and then the hydrated water of the alkaline earth metal salt hydrate is evaporated to obtain the main hydrate. A method for obtaining the composition of the invention can also be employed, but such a method is difficult to employ because foaming tends to occur in the composition.

  The composition of the present invention can also be obtained directly by melt-kneading the raw materials, but from the viewpoint of industrial handling, composition pellets are obtained after the above-mentioned melt-kneading, and this is melt-molded. To obtain a melt-molded product. From the viewpoint of economy, a method of melt-kneading using an extruder, extruding into a strand, and cutting and pelletizing is preferable.

  The shape of the pellet includes, for example, a spherical shape, a cylindrical shape, a cubic shape, a rectangular parallelepiped shape, etc., but is usually a spherical shape (rugby ball shape) or a cylindrical shape, and its size is convenient when used as a molding material later. In the case of a spherical shape, the diameter is usually 1 to 6 mm, preferably 2 to 5 mm, the height is usually 1 to 6 mm, and preferably 2 to 5 mm. -6 mm, preferably 2-5 mm, and the length is usually 1-6 mm, preferably 2-5 mm.

  In order to stabilize the feed property at the time of melt molding, it is also preferable to attach a lubricant to the surface of the obtained pellet. Examples of the lubricant include higher fatty acids (eg, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid metal salts (higher fatty acid aluminum salts, calcium salts, zinc salts, magnesium salts, barium). Salts), higher fatty acid esters (methyl esters of higher fatty acids, isopropyl esters, butyl esters, octyl esters, etc.), higher fatty acid amides (saturated fatty acid amides such as stearic acid amide and behenic acid amide), oleic acid amides, erucic acid amides, etc. Unsaturated fatty acid amides, ethylene bis stearic acid amides, ethylene bis oleic acid amides, ethylene biserucic acid amides, bis fatty acid amides such as ethylene bis lauric acid amides), low molecular weight polyolefins (for example, low molecular weight of about 500 to 10,000) Min Polyethylene, low molecular weight polypropylene, etc., or acid-modified products thereof), higher alcohols, ester oligomers, fluorinated ethylene resins, and the like, preferably higher fatty acids and / or metal salts, esters, and amides thereof are more preferable. A higher fatty acid metal salt and / or a higher fatty acid amide is used.

  As the properties of the lubricant, any properties such as solid (powder, fine powder, flakes, etc.), semi-solid, liquid, paste, solution, emulsion (aqueous dispersion) can be used. However, in order to efficiently obtain the target pellet of the present invention, an emulsion is preferable.

  The adhesion amount of the lubricant is preferably 10 to 1000 ppm, more preferably 20 to 500 ppm, and particularly preferably 50 to 250 ppm with respect to the pellets, from the viewpoint of stabilizing the feed property at the time of melt molding.

<Melformed product>
The polar group-modified polymer composition of the present invention can be formed into, for example, a film, a sheet, a cup or a bottle by a melt molding method. Examples of the melt molding method include extrusion molding methods (T-die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.), injection molding methods, and the like. In many cases, the melt molding temperature is usually selected from the range of 150 to 300 ° C.

  The melt-molded product containing the polar group-modified polymer composition of the present invention may be used for various applications as it is. At this time, the thickness of the layer of the polar group-modified polymer composition is usually 1 to 5000 μm, preferably 5 to 4000 μm, and particularly preferably 10 to 3000 μm or more.

  The melt-molded product formed by molding the polar group-modified polymer composition of the present invention is usually in a state where the component (B) is dispersed in the polar group-modified polymer (A).

<Multilayer structure>
The multilayer structure of the present invention has at least one layer (polar group-modified polymer composition layer) composed of the polar group-modified polymer composition of the present invention. In other words, the polar group-modified polymer composition layer of the present invention is a multilayer combined with a thermoplastic resin (or composition thereof) layer other than the polar group-modified polymer (hereinafter simply referred to as “thermoplastic resin layer”). It is a structure.

(1) Thermoplastic resin layer The thermoplastic resin layer contained in the multilayer structure of the present invention is a layer of a thermoplastic resin other than the polar group-modified polymer or a composition thereof.
Examples of the thermoplastic resin other than the polar group-modified polymer include linear low density polyethylene, low density polyethylene, ultra low density polyethylene, medium density polyethylene, high density polyethylene, and ethylene-propylene (block and random) copolymer. , Polyethylene resins such as ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, polypropylene, polypropylene such as propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, etc. (Unmodified) olefinic resins such as olefinic resins, polybutene, polypentene, and cyclic olefinic resins (polymers having a cyclic olefin structure in the main chain and / or side chain); these polyolefins as unsaturated carboxylic acids or esters thereof Unsaturated carboxylic acid-modified olefin resin graft modified with Olefin resins in a broad sense including modified olefin resins; ethylene-vinyl ester resins such as ionomers and ethylene-vinyl acetate copolymers and saponified products thereof, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers , Polyester resin, polyamide resin (including copolyamide), polyvinyl chloride, polyvinylidene chloride, acrylic resin, polystyrene, vinyl ester resin, polyester elastomer, polyurethane elastomer, polystyrene elastomer, chlorinated polyethylene Halogenated polyolefins such as chlorinated polypropylene, aromatic or aliphatic polyketones, and the like.

  As the above-mentioned “thermoplastic resin” raw material, as in the above example, a raw material derived from petroleum such as naphtha is usually used, but a raw material derived from natural gas such as shale gas, sugar cane, sugar beet, corn, potato, etc. Plant-derived raw materials purified from components such as sugar and starch contained in the above, or components such as cellulose contained in rice, wheat, millet, grass plants and the like may be used.

  The resin as described above is not limited to one type, and may be a mixture of two or more types, and is not limited to a virgin resin, and recycles end portions and defective products generated in the process of manufacturing a multilayer structure. It may be a recycled resin containing a mixture of various resins obtained by melt molding.

Such a thermoplastic resin layer is appropriately selected according to the purpose, such as increasing the strength of the multilayer structure, imparting other functions such as gas barrier properties, depending on the type of the main resin.
As a thermoplastic resin preferably used in the multilayer structure of the present invention, a hydrophobic resin and a gas barrier resin will be described in detail below.

(1-1) Hydrophobic resin Hydrophobic resins are preferably used for the purpose of absorbing water from the surface of the multilayer structure, preventing moisture absorption, and imparting strength.
The hydrophobic resin is preferably, for example, an olefin resin, a polyester resin, or a polystyrene resin, and more preferably a polyethylene resin, a polypropylene resin, a polycyclic olefin resin, or an unsaturated carboxylic acid-modified olefin resin thereof. In particular, polypropylene resins and cyclic olefin resins are preferably used as hydrophobic resins.

  In addition, as said cyclic olefin resin, well-known resin (For example, refer Unexamined-Japanese-Patent No. 2003-103718, Unexamined-Japanese-Patent No. 5-177777, and special table 2003-504523 etc.) can be used. The cyclic olefin-based resin has a low moisture permeability as compared with a chain aliphatic polyolefin such as polyethylene and polypropylene. For this reason, in the multilayer structure including the moisture absorption layer, by using the cyclic olefin-based resin on the surface layer of the multilayer structure or the side close to the surface layer, it is possible to reduce the amount of moisture mixed from the outside due to moisture or hot water treatment, As a result, the moisture resistance of the multilayer structure can be improved.

  The above hydrophobic resins may be used alone or in admixture of two or more. Moreover, you may use combining the said hydrophobic resin and thermoplastic resins other than hydrophobic resin.

(1-2) Gas Barrier Resin Among the thermoplastic resins, the oxygen permeability measured according to the method described in JIS-K7126 (isobaric method) at 20 ° C. and 65% relative humidity is 100 mL · 20 μm / ( m ² · day · atm) or less, preferably 50 mL · 20 µm / (m ² · day · atm) or less, more preferably 10 mL · 20 µm / (m ² · day · atm) or less. It has a function. In the present specification, a thermoplastic resin satisfying such oxygen permeability may be particularly referred to as a “gas barrier resin”.
When it is desired to give a gas barrier function to the multilayer structure, it is preferable that a gas barrier resin layer (gas barrier layer) as described above is included.

Specific examples of the gas barrier resin include polyvinyl alcohol resins such as polyvinyl alcohol resin (PVOH) and EVOH resin, and polyamides such as polycaprolactam (nylon 6) and metaxylenediamine / adipic acid copolymer (nylon MXD6). Resin, polyethylene terephthalate (PET), polyglycolic acid (PGA), polyester resins such as aromatic liquid-crystalline polyester, polyvinylidene chloride (PVDC), acrylonitrile copolymer (PAN), polyvinylidene fluoride, polychlorotrifluoroethylene, etc. Can be mentioned.
A gas barrier resin may be comprised from single resin or its composition, and may be comprised from the composition of multiple types of resin mixture, as long as gas barrier resin is included.

  Among these gas barrier resins, from the viewpoint of gas barrier properties, PVOH resin, EVOH resin, nylon MXD6, PGA, PVDC, and PAN are preferable. In addition to better gas barrier properties, melt moldability and the resin composition layer of the present invention EVOH resin is particularly preferable from the viewpoint of adhesiveness.

  The EVOH resin used here is a saponified ethylene-vinyl ester copolymer, and generally corresponds to an EVOH resin having an ethylene structural unit of 20 to 60 mol% measured based on ISO14663. As vinyl ester monomers, in addition to vinyl acetate, for example, vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate And the like, and aromatic vinyl esters such as vinyl benzoate. In addition, the olefin, hydroxy group-containing α-olefins, esterified products, acylated products, dialkyl esters, (meth) acrylamides, N-vinylamides, vinyl cyanides, vinyl ethers, halogenated compounds at 10 mol% or less. EVOH resin in which other monomers such as vinyl compounds, vinyl silanes, halogenated allyl compounds, allyl alcohols, etc. are copolymerized, as well as “post-modification” such as urethanization, acetalization, cyanoethylation, oxyalkyleneation, etc. EVOH resins made are also included. Moreover, what is called a side chain 1, 2-diol containing EVOH resin containing the structural unit shown by following (1) is also contained.

(1) In the formula, R ¹ , R ² , and R ³ each independently represent a hydrogen atom or an organic group, X represents a single bond or a bond chain, and R ⁴ , R ⁵ , and R ⁶ each independently Represents a hydrogen atom or an organic group.

The organic group in the 1,2-diol structural unit represented by the general formula (1) is not particularly limited, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group. And saturated hydrocarbon groups such as tert-butyl group, aromatic hydrocarbon groups such as phenyl group and benzyl group, halogen atom, hydroxyl group, acyloxy group, alkoxycarbonyl group, carboxyl group and sulfonic acid group.
R ^{1 to} R ³ are preferably a saturated hydrocarbon group or a hydrogen atom having 1 to 30 carbon atoms, particularly 1 to 15 carbon atoms, more preferably 1 to 4 carbon atoms, and most preferably a hydrogen atom. R ^{4 to} R ⁶ are preferably an alkyl group having 1 to 30 carbon atoms, particularly 1 to 15 carbon atoms, more preferably 1 to 4 carbon atoms, or a hydrogen atom, and most preferably a hydrogen atom. In particular, it is most preferable that R ^{1 to} R ⁶ are all hydrogen.

The most preferable structure in the 1,2-diol structural unit represented by the general formula (1) is one in which R ^{1 to} R ⁶ are all hydrogen atoms and X is a single bond. That is, the structural unit represented by the following structural formula (1a) is most preferable.

(1-3) Additives In addition to the resin components described above, additives that are generally blended with thermoplastic resins may be appropriately contained in the thermoplastic resin layer. For example, desiccant, heat stabilizer, antioxidant, antistatic agent, colorant, UV absorber, lubricant, plasticizer, light stabilizer, surfactant, antibacterial agent, antiblocking agent, flame retardant, crosslinking agent, Hardeners, foaming agents, crystal nucleating agents, antifogging agents, biodegradable additives, silane coupling agents, inorganic fillers (kaolin, mica, smectite, etc.), oxygen absorbers (inorganic oxygen absorbers, polyoctenylene, etc.) A heavy bond-containing compound) may be contained.

  Examples of the heat stabilizer include organic acids such as acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, and behenic acid, or the like for the purpose of improving various physical properties such as heat stability during melt molding. Alkali metal salts (sodium, potassium, etc.), alkaline earth metal salts (calcium, magnesium, etc.), salts such as zinc salts; or inorganic acids such as sulfuric acid, sulfurous acid, carbonic acid, phosphoric acid, boric acid, or alkalis thereof Metal salts (such as sodium and potassium), alkaline earth metal salts (such as calcium and magnesium), and zinc salts can be used. Of these, it is particularly preferable to add boron compounds, acetates and phosphates including acetic acid, boric acid and salts thereof.

When an EVOH resin is used as the gas barrier resin, the amount of acetic acid added is usually 0.001 to 1 part by weight, preferably 0.005 to 0.2 part by weight, particularly preferably 0.001 part by weight based on 100 parts by weight of the EVOH resin. 0.10 to 0.1 parts by weight. The added amount of the boron compound is usually 0.001 to 1 part by weight in terms of boron (analyzed by ICP emission analysis after ashing) with respect to 100 parts by weight of the EVOH resin, and preferably 0.002 to 0.001. 2 parts by weight, particularly preferably 0.005 to 0.1 parts by weight. The addition amount of acetate and phosphate (including hydrogen phosphate) is usually 0.0005 to 0 in terms of metal (after ashing and analyzed by ICP emission spectrometry) with respect to 100 parts by weight of EVOH resin. 0.1 part by weight, preferably 0.001 to 0.05 part by weight, particularly preferably 0.002 to 0.03 part by weight.
If the amount added is too large, it tends to be difficult to obtain a homogeneous thermoplastic resin layer.

(2) Layer structure of multilayer structure The multilayer structure of the present invention includes at least one polar group-modified polymer composition layer of the present invention. Depending on the intended properties, the thermoplastic resin as described above 1 type or 2 types or more are included.
When two or more polar group-modified polymer composition layers are included, the types of polar group-modified polymer may be different. Similarly, when two or more thermoplastic resin layers are included, different types of thermoplastic resin layers may be included.

Therefore, as the layer structure of the multilayer structure, the polar group-modified polymer composition layer of the present invention is I (I ₁ , I ₂ ,...), And the thermoplastic resin layer is II (II ₁ , II ₂ ,. ..), I / II two-layer structure, I / II / I, II / I / II three-layer structure, I / II ₁ / II ₂ / I, II / I ₁ / I ₂ / II 4 layers structure such as I ₁ / II / I ₂ / II / I ₁ , II ₁ / I / II ₂ / I / II ₁ , II ₁ / I ₁ / II ₂ / I ₂ / II ₁ structure, of any such _{II 1 / I 1 / II 3} / I 2 / II 2 / I 2 / II 3 / II 1, II 1 / I 1 / I 2 / II 2 / I 2 / I 1 / II 1 Combinations are possible.

  When focusing on the function and characteristics, the layer constituting the multilayer structure is, for example, a hydrophobic resin layer used for imparting strength or protecting the surface of the hygroscopic layer, when a gas barrier function is required. In order to increase the bonding strength of the gas barrier layer and the laminated layers, an adhesive resin layer or an appropriate combination of these layers can be used.

When two or more types of thermoplastic resin layers are included, a layer using a hydrophobic resin such as polypropylene (for example, II ₁ ) and a gas barrier resin layer (for example, II ₂ ), and a thermoplastic resin layer having other functions (II ₃₎ ), It is possible to combine thermoplastic resin layers having different roles.
The number of layers of the multilayer structure is generally 2 to 15, and preferably 3 to 10 in total.

  The polar group-modified polymer composition layer is preferably used in combination with a thermoplastic resin layer whose characteristics tend to deteriorate due to moisture absorption, that is, a moisture absorption layer. By using the hygroscopic layer in combination with the polar group-modified polymer composition layer of the present invention, even if the hygroscopic layer does not contain a desiccant, it is possible to suppress deterioration in characteristics due to moisture absorption of the hygroscopic layer. In this case, the polar group-modified polymer composition layer of the present invention is preferably laminated so as to be adjacent to the hygroscopic layer, that is, includes a “thermoplastic resin layer / polar group-modified polymer” unit. This is because the effect of imparting moisture resistance to the polar group-modified polymer composition layer of the present invention tends to increase as the polar group-modified polymer composition layer of the present invention is arranged closer to the thermoplastic resin layer as the moisture-absorbing layer. .

  Therefore, for example, in the case where the thermoplastic resin layer is a gas barrier resin layer mainly composed of a vinyl alcohol-based resin such as EVOH resin, the adhesiveness disposed between the surface and the hydrophobic resin used for imparting strength, etc. It is effective to use the polar group-modified polymer composition layer of the present invention as the resin layer. In other words, a unit in which the polar group-modified polymer composition layer of the present invention is used as a boundary layer between the hygroscopic layer composed of a vinyl alcohol resin and the hydrophobic resin layer as the adhesive resin layer of both layers. A multilayer structure including “hydrophobic resin layer / polar group-modified polymer composition layer / gas barrier layer” is preferable.

(3) Manufacture of multilayer structure Lamination | stacking with a polar group modified polymer composition layer and a thermoplastic resin layer can be performed by a well-known method. For example, a method of melt extrusion laminating a thermoplastic resin constituting a thermoplastic resin layer on a film or sheet of the polar group modified polymer composition of the present invention, a polar group modified polymer composition of the present invention on a thermoplastic resin layer A method of melt extrusion laminating a product, a method of co-extrusion with the polar group-modified polymer composition of the present invention, a polar group-modified polymer composition (layer) of the present invention and a thermoplastic resin (layer), an organic titanium compound, Dry lamination using known adhesives such as isocyanate compounds, polyester compounds, polyurethane compounds, etc., applying the solution of the polar group-modified polymer composition of the present invention on the thermoplastic resin layer, and then removing the solvent And the like. Among these, the co-extrusion method is preferable from the viewpoint of cost and environment.

  The multilayer structure as described above is then subjected to (heating) stretching treatment as necessary. The stretching treatment may be either uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. As the stretching method, a roll stretching method, a tenter stretching method, a tubular stretching method, a stretching blow method, a vacuum / pressure forming method, or the like having a high stretching ratio can be employed. The stretching temperature is a temperature in the vicinity of the multilayer structure and is usually selected from the range of about 40 to 170 ° C, preferably about 60 to 160 ° C. If the stretching temperature is too low, the stretchability becomes poor, and if it is too high, it becomes difficult to maintain a stable stretched state.

In addition, you may heat-set next for the purpose of providing dimensional stability after extending | stretching. The heat setting can be carried out by a known means. For example, the stretched film is usually heat-treated at 80 to 180 ° C., preferably 100 to 165 ° C. for about 2 to 600 seconds while keeping the stretched state.
Further, when the multilayer stretched film obtained from the polar group-modified polymer composition of the present invention is used as a shrink film, in order to impart heat shrinkability, the above heat setting is not performed, for example, after stretching What is necessary is just to perform the process of cooling and fixing a film by applying cold air.

  In some cases, it is also possible to obtain cups or tray-like multilayer containers from the multilayer structure of the present invention. In that case, usually a drawing method is employed, and specific examples include a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a plug assist type vacuum forming method. Furthermore, when a tube or bottle-shaped multilayer container is obtained from a multilayer parison (a hollow tubular preform before blow), a blow molding method is adopted. Specifically, an extrusion blow molding method (double-head type, mold transfer type, Parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison type blow molding method, injection blow molding method, biaxial stretch blow molding method (extrusion type cold parison biaxial stretch blow molding method, injection type cold) Parison biaxial stretch blow molding method, injection molding inline biaxial stretch blow molding method, etc.). The obtained laminate is subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making processing, deep drawing processing, box processing, tube processing, split processing, etc. as necessary. Can do.

(4) Structure of multilayer structure Thickness of multilayer structure (including stretched one), and further, the polar group-modified polymer composition layer of the present invention constituting the multilayer structure, and a thermoplastic resin layer such as a gas barrier layer The thickness of the layer structure, the type of the layer constituent resin, the type of adhesive resin, the application and packaging form, the required physical properties, etc. can not be said unconditionally, the thickness of the multilayer structure (including stretched) is, Usually, it is 10-5000 micrometers, Preferably it is 30-3000 micrometers, Most preferably, it is 50-2000 micrometers. The polar group-modified polymer composition layer of the present invention is usually 0.5 to 250 μm, preferably 1 to 150 μm, particularly preferably 3 to 100 μm. The gas barrier layer is usually 1 to 500 μm, preferably 3 to 300 μm, particularly preferably 5 to 200 μm. The thickness of the thermoplastic resin layer (for example, a hydrophobic resin layer) other than the gas barrier layer is usually 5 to 30000 μm, preferably 10 to 20000 μm, and particularly preferably 20 to 10,000 μm.

  Furthermore, the thickness ratio of the gas barrier layer and the polar group-modified polymer composition layer of the present invention (gas barrier layer / polar group-modified polymer composition layer) in the multilayer structure is such that when there are a plurality of layers, the thickest layers The ratio is usually 10/90 to 99/1, preferably 20/80 to 95/5, particularly preferably 50/50 to 90/10. The ratio of the thickness of the gas barrier layer to the thermoplastic resin layer (other thermoplastic resin layer) other than the gas barrier layer (gas barrier layer / other thermoplastic resin layer) is the thickest when there are a plurality of layers. The ratio between the layers is usually 1/99 to 50/50, preferably 5/95 to 45/55, and particularly preferably 10/90 to 40/60.

(5) Applications Bags and cups made of films, sheets, stretched films, cups, trays, tubes, bottles, and the like obtained as described above, and seasonings such as mayonnaise and dressing in addition to general foods It is useful as various packaging material containers for fermented foods such as miso, fats and oils such as salad oil, beverages, cosmetics, and pharmaceuticals.
In particular, since the layer made of the polar group-modified polymer composition of the present invention can impart moisture resistance to the entire multilayer structure, it has a gas barrier layer whose gas barrier property is reduced by moisture absorption and is subjected to hydrothermal treatment. It is particularly useful as a food packaging material.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the description of the examples unless it exceeds the gist.
In the examples, “part” means a weight basis.

<Measurement evaluation method>
[Water absorption characteristics of hydrate-forming metal salts]
(1) Water Content of Hydrate-Forming Metal Salt The water content of the hydrate-forming metal salt was measured using a thermogravimetric apparatus “Pyris1 TGA (manufactured by PerkinElmer)”.
As for the water content of the completely dehydrated product, the water content was removed by heating, and the water content when the weight equilibrium was reached was defined as the water content of the completely dehydrated product.

(2) Water absorption at 40 ° C. and 90% relative humidity: Xn (g)
The hydrate-forming metal salt was left for 6 days at 40 ° C. and 90% relative humidity. The amount of water absorption Xn per 100 g of the hydrate-forming metal salt after being left for n days at 40 ° C. and 90% relative humidity is determined by the following formula.
Xn = [(Water absorption amount for n days) / (Initial weight)] × 100
The “water absorption amount for n days” was determined by measuring the weight (g) after n days from the start of standing (n = 1 to 6 natural number) and subtracting the initial weight.
The “initial weight” and “weight after n days” were measured with an electronic balance after placing a sample on an aluminum cup.

(3) Crystal water content of maximum hydrate: Y (g)
It calculated | required by the following formula.
Y = [(maximum hydrate number × 18) / (anhydride molecular weight)] × 100
As the molecular weight of the anhydride, the molecular weight obtained from the chemical formula of the target metal salt was employed. The hydrate number of the maximum hydrate is the hydrate shown in [] of the following compounds.
Trimagnesium dicitrate [14 hydrate], Trisodium citrate [dihydrate]

(4) Water absorption after 24 hours when left at 40 ° C. and 90% relative humidity: Z ([g / 100 g of hydrate-forming metal salt] / day)
The value of water absorption (X ₁ ) after 1 day of standing measured by the method described in (2) above was adopted as Z.

(5) Maximum point of water absorption amount Based on the measurement of the change in water absorption amount for 6 days when left at 40 ° C. and 90% relative humidity, measured in (2) above, the water absorption amount for n days (X _n ) And (n + 1) days of water absorption (X _{n + 1} ), if there is a day when X _{n + 1} is smaller, there is a maximum point of water absorption.

[Characteristics of resin composition]
(6) Moisture resistance After leaving the resin composition pellets in a thermostatic chamber set at 30 ° C. and 90% relative humidity for 3 days, the appearance of the pellets was visually observed. When there was no particular change in the appearance, it was judged as “good”.

[Evaluation of multilayer structure]
(7) Oxygen permeability after retort treatment (cc / m ² · day · atm)
A sample piece (10 cm × 10 cm) of the multilayer structure was taken out after retorting at 123 ° C. for 33 minutes using a hot water immersion type retort apparatus (Hisaka Seisakusho). Three days after this retort treatment, oxygen permeability (23 ° C., internal relative humidity: 90%, external relative humidity: 50%) using an oxygen gas permeation measuring device (manufactured by Mocon, OX-TRAN 2/20) ) Was measured.

(8) Moisture resistance of multilayer structure The multilayer structure was allowed to stand for 40 days in a thermo-hygrostat set to 40 ° C and 90% relative humidity, and then the appearance of the multilayer structure was visually observed. When there was no particular change in the appearance, it was judged as “good”.

[Types of hydrate-forming metal salts and water absorption characteristics]
The water absorption characteristics of the following hydrate-forming metal salts used in this example were examined by the above method. The measurement results are shown in Table 1.
Trimagnesium dicitrate (completely dehydrated): Trimagnesium dicitrate (anhydrous) manufactured by Aadhunik Industries was used. The moisture content measured with a thermogravimetric apparatus was 0.4%.
Trisodium citrate (completely dehydrated): Trisodium citrate (anhydrous) from Iwata Chemical Industry was used. The moisture content measured with a thermogravimetric apparatus was 0.4%.

Trisodium citrate, which is an alkali metal salt, has a large water absorption, and the value of X ₅ / Y exceeds 2.0, whereas trimagnesium dicitrate, which is an alkaline earth metal salt, has X ₅ / The value of Y was within the range of 0.2 to 2.0, and the water absorption amount had a maximum point. It can be seen that trimagnesium dicitrate tends to approach the state of water absorption close to that of stable hydrates after once absorbing water that exceeds the amount of water of crystallization that can be contained as a stable hydrate.

[Production and Evaluation of Polar Group-Modified Polymer Composition M1-M4]
As the polar group-modified polymer (A), a polypropylene resin modified with maleic anhydride (“Admer QF500”, MFR 3.0 g / 10 min (230 ° C., load 2160 g)) or maleic anhydride modified with maleic anhydride Linear low-density polyethylene (maleic anhydride-modified LLDPE “Admer NF528” from Mitsui Chemicals, Inc., MFR 2.2 g / 10 min (210 ° C., load 2160 g)) was used, as shown in Table 2. Polar group modification A polymer and a hydrate-forming metal salt were blended in a predetermined ratio, blended, charged into a feeder, and melt-kneaded under the following conditions in a twin-screw extruder having two mixing zones. The polar group-modified polymer composition thus prepared was extruded into a strand shape, cut with a drum-type pelletizer, and cylindrical pellets (pellet) Preparative diameter: 2 mm, pellet length: yield 0.07%) of: 3.5 mm, volatiles.

Melting and kneading conditions used for the production of the polar group-modified polymer composition M1-M4-twin screw extruder: diameter 32 mm, L / D = 56 (manufactured by Nippon Steel Works)
Extruder set temperature: C2 / C3 / C4 / C5 / C6 / C7 / C8 / C9 / C10 / C11 / C12 / C13 / C14 / C15 / C16 / D = 110/140/200/230/230/230 / 230/230/230/230/230/230/230/230/230/230 ° C.
・ Screw rotation speed: 240ppm
・ Discharge rate: 25 kg / hour ・ Cooling of strand: Water cooling ・ Taking speed: 20 m / min

  The polar group-modified polymer composition pellets M1-M4 prepared above were evaluated for moisture resistance based on the above evaluation method. The results are shown in Table 2.

  As can be seen from Table 2, when the alkaline earth metal salt satisfying the water absorption characteristics defined in the present invention was contained (M1, M2), no change in appearance was observed even after storage under high humidity. On the other hand, when the alkali metal salt that cannot satisfy the water absorption characteristics defined in the present invention is contained (M3, M4), the pellet surface was wet. Trisodium citrate, which absorbs a large amount of water, has deliquescence, and as a result of water absorption and deliquescence, the alkali metal salt solution generated by deliquescence seems to bleed on the pellet surface.

[Production and Evaluation of Multilayer Structures S1-S3]
A polar group-modified polymer composition (M1 or M3) is used as the adhesive resin layer, and the gas barrier resin contains an ethylene structural unit content of 29 mol%, a saponification degree of 99.6 mol%, and a boric acid content of 500 ppm ( Saponified ethylene-vinyl acetate copolymer (converted from boron analysis value) (MFR 4.3 g / 10 min (210 ° C., load 2160 g)) was used as the hydrophobic resin layer (Nippon Polypro Co., Ltd. “Novatech PP EA7AD”) That is, the gas barrier layer (EVOH resin layer) and the hydrophobic resin layer correspond to the thermoplastic resin layer.
A chill roll in which co-extrusion is carried out under the following conditions using a co-extrusion multi-layer film forming apparatus having three extruders, a three-type five-layer feed block, a multi-layer film forming die, and a take-out machine. And a multilayer structure of 3 types and 5 layers having a thickness of 320 μm (hydrophobic resin (PP) / polar group-modified polymer composition / EVOH resin / polar group-modified polymer composition / hydrophobic resin (PP) , Thickness (μm): 120/20/40/20/120).
The multilayer structure S1 is obtained by using, as an adhesive resin layer, a polar group-modified polymer composition layer containing an alkaline earth metal salt having a water absorption ability specified in the present invention, and corresponds to the multilayer structure of the present invention. To do.

Intermediate layer extruder (EVOH resin): 40 mmφ single screw extruder (barrel temperature: 230 ° C.)
・ Inner / outer layer extruder (hydrophobic resin (PP)): 40 mmφ single screw extruder (barrel temperature: 230 ° C.)
・ Inner / outer layer extruder (polar group-modified polymer composition): 32 mmφ single screw extruder (barrel temperature: 230 ° C.)
-Die: 3 types, 5 layers type feed block die (die temperature: 230 ° C)
・ Cooling roll temperature: 50 ° C

  About the multilayer structure S1-S3 created above, based on the said evaluation method, the oxygen permeability after a retort process and the moisture resistance of a multilayer structure were evaluated. The results are shown in Table 3.

  In the multilayer structure S3 using an adhesive resin layer that does not contain a metal salt serving as a desiccant, no appearance defect was observed due to storage under high temperature and high humidity. However, since the moisture absorption effect by the metal salt cannot be obtained, the gas barrier layer subjected to the retort treatment absorbs moisture based on the original hygroscopic property, and as a result, the gas barrier property of the multilayer structure is lowered.

  The multilayer structure S2 is a case where a polar group-modified polymer composition layer serving as an adhesive resin layer contains a hydrate-forming alkali metal salt. Because of the moisture absorption of the hydrate-forming alkali metal salt, the oxygen barrier property was excellent even after retorting. However, the film appearance after storage for 40 days under high humidity is inappropriate as a packaging film in which spots appear and the appearance is a problem. It is considered that the alkali metal salt having deliquescence becomes an alkali metal salt solution as a result of moisture absorption, bleeds out from the adhesive resin layer, and accumulates with the hydrophobic resin layer to form spots.

  On the other hand, the multilayer structure S1 is a polar group-modified polymer composition layer of the present invention as an adhesive resin layer interposed between the EVOH resin layer whose characteristics (gas barrier properties) are reduced by moisture absorption and the hydrophobic resin layer. Is adopted. Although the oxygen permeation amount after the retort treatment was higher than that of the multilayer structure S2, it was about ¼ or less of the oxygen permeation amount of the multilayer structure S3 using the adhesive resin layer containing no desiccant. Moreover, no change was observed in the film appearance even after storage under high humidity. It turns out that multilayer structure S3 can suppress the fall of the gas barrier property by moisture absorption, without affecting an external appearance as a packaging film.

Even if the polar group-modified polymer composition of the present invention absorbs moisture, it does not affect the appearance. Therefore, when the multilayer structure including the polar group-modified polymer composition layer of the present invention is used in combination with a resin layer in which properties such as gas barrier properties are reduced by moisture absorption, without affecting the appearance, This is useful because it can be used as an adhesive resin that can suppress a decrease in gas barrier properties and can improve the bonding strength between the hydrophobic resin and the hygroscopic layer.

Claims (10)

(A) a polar group-modified polymer in which a polymer having an aliphatic hydrocarbon monomer unit containing a carbon-carbon double bond is modified with a polar group-containing compound; and (B) the water absorption property of (I) below A polar group-modified polymer composition comprising a hydrate-forming alkaline earth metal salt satisfying
(Α) The alkaline earth metal salt (B) with respect to the crystallization water content (Y) in the maximum hydrate of the alkaline earth metal salt (B) was left in an environment of 40 ° C. and 90% relative humidity. The ratio (X ₅ / Y) of water absorption (X ₅ ) per 100 g of the alkaline earth metal salt (B) for 5 days is 0.2 to 2.0. The polar group-modified polymer composition according to claim 1, wherein the hydrate-forming alkaline earth metal salt (B) further satisfies the following water absorption property (β):
(Β) The water absorption (Z) per 100 g after 24 hours when the alkaline earth metal salt (B) is allowed to stand at 40 ° C. and 90% relative humidity is 10 g or more. The polar group-modified polymer composition according to claim 1 or 2, wherein the hydrate-forming alkaline earth metal salt (B) further satisfies the following water absorption property (γ).
(Γ) It has a maximum point of water absorption when left at 40 ° C. and 90% relative humidity.   When the alkaline earth metal salt (B) is a mixture of an alkaline earth metal salt of one acid selected from the group consisting of lactic acid, silicic acid, phosphoric acid, and citric acid, the total dehydration or water content is 50 wt. The polar group-modified polymer composition according to any one of claims 1 to 3, wherein the polar group-modified polymer composition is a partially dehydrated product or a mixture thereof.   The content weight ratio (A / B) of the polar group-modified polymer (A) and the hydrate-forming alkaline earth metal salt (B) is more than 50 / less than 50 to 99/1. The polar group-modified polymer composition according to any one of claims 1 to 4.   The polar group-modified polymer composition according to claim 1, wherein the polar group-modified polymer (A) is a carboxyl group-modified olefin polymer.   A multilayer structure comprising at least one layer formed of the polar group-modified polymer composition according to claim 1. Further, a gas barrier layer having an oxygen permeability of 100 mL · 20 μm / (m ² · day · atm) or less measured at 20 ° C. and 65% relative humidity according to the method described in JIS-K7126 (isobaric method). The multilayer structure according to claim 9 or 10, wherein the multilayer structure is included.   9. The multilayer structure according to claim 8, wherein the gas barrier layer is a layer of a saponified ethylene-vinyl ester copolymer or a composition thereof. Furthermore, a layer of a hydrophobic resin or a composition thereof is included, the layer of the polar group-modified polymer composition is laminated on the hydrophobic resin or a composition layer thereof, and the layer of the polar group-modified polymer composition is The multilayer structure according to claim 8 or 9, further comprising a laminated unit in which the gas barrier layers are laminated.