JP6561799B2 - Multilayer structure - Google Patents

Description

  The present invention provides a multilayer structure in which a cyclic olefin resin layer (γ) is provided on at least one surface of an ethylene-vinyl ester copolymer saponified product layer (α) via an acid-modified olefin elastomer layer (β). In particular, the present invention relates to a multilayer structure that suppresses bag breakage due to piercing during retort processing.

The saponified ethylene-vinyl ester copolymer (hereinafter sometimes referred to as “EVOH resin”) exhibits excellent gas barrier properties against oxygen. Therefore, a multilayer structure having EVOH resin as an intermediate layer and thermoplastic resin as inner and outer layers is widely used as a packaging film for foods and the like.
However, when this multilayer structure is subjected to hot water treatment for a long time like retort treatment, there are disadvantages that the gas barrier properties immediately after the treatment are deteriorated, whitened, or the shape cannot be maintained.

  In general, a layer made of a thermoplastic resin having better water resistance is used as an inner / outer layer as a method for suppressing such drawbacks, particularly the decrease in gas barrier properties, with respect to the retort treatment.

Examples of the thermoplastic resin having excellent water resistance include cyclic olefin resins, and Patent Document 1 proposes a multilayer structure using cyclic olefin resins for the inner and outer layers.
However, in the invention described in Patent Document 1, polypropylene modified with maleic anhydride used as an adhesive resin for the cyclic olefin resin layer and the EVOH resin layer has poor adhesion to both layers, and there is room for improvement.

  Furthermore, as a multilayer structure with improved adhesion between the cyclic olefin resin layer and the EVOH resin layer, Patent Document 2 proposes a multilayer structure using an acid-modified olefin elastomer as an adhesive resin.

JP-A-4-276253 JP 2010-274595 A

However, the multilayer structure according to the invention described in Patent Document 2 has a problem in that bag breakage due to piercing tends to occur during retort processing.
Therefore, a multilayer structure having an EVOH resin layer as a gas barrier layer and a cyclic olefin resin layer on the inner and outer layers and capable of suppressing bag breakage due to piercing during retort processing is desired.

  As a result of intensive studies in view of the above circumstances, the present invention is a multilayer in which a cyclic olefin resin layer (γ) is provided on at least one surface of the EVOH resin layer (α) via an acid-modified olefin elastomer layer (β). In the structure, the above-mentioned problem can be solved by using a cyclic olefin resin having a glass transition point of 85 to 130 ° C., and further containing 5 to 1000 ppm of alkali metal in the EVOH resin. The present invention has been completed.

The multilayer structure of the present invention can suppress bag breakage due to piercing during retort processing.
This includes a cyclic olefin resin layer (γ) / acid-modified olefin elastomer layer (β) having a specific glass transition point, and an EVOH resin layer (α) / acid-modified olefin elastomer containing a specific amount of alkali metal. Since the balance of both adhesive properties at the interface of the layer (β) is excellent, it is considered that the puncture resistance is improved.

  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.

  The multilayer structure of the present invention is a multilayer structure in which a cyclic olefin resin layer (γ) is provided on at least one surface of an EVOH resin layer (α) via an acid-modified olefin elastomer layer (β). As the cyclic olefin-based resin, a resin having a specific glass transition point is used, and the EVOH resin composition contains an alkali metal.

First, the EVOH resin layer (α) will be described.
<EVOH resin layer (α)>
The EVOH resin used in the present invention is a resin usually obtained by saponifying a copolymer of ethylene and a vinyl ester monomer (ethylene-vinyl ester copolymer), and is a water-insoluble thermoplastic resin. It is. The polymerization can also be carried out using any known polymerization method such as solution polymerization, suspension polymerization, and emulsion polymerization. Generally, solution polymerization using methanol as a solvent is used. Saponification of the obtained ethylene-vinyl ester copolymer can also be performed by a known method.
The EVOH resin produced in this way is mainly composed of ethylene-derived structural units and vinyl alcohol structural units, and contains a slight amount of vinyl ester structural units remaining without saponification.

  As the vinyl ester monomer, vinyl acetate is typically used from the viewpoint of market availability and good impurity treatment efficiency during production. Examples of other vinyl ester monomers include, for example, fats such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate. Aromatic vinyl esters such as aromatic vinyl esters and vinyl benzoates, and the like. Usually, aliphatic vinyl esters having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms are used. it can. These are usually used alone, but a plurality of them may be used simultaneously as necessary.

  The content of the ethylene structural unit in the EVOH resin is a value measured based on ISO14663, and is usually 20 to 60 mol%, preferably 25 to 55 mol%, particularly preferably 29 to 48 mol%. When the content is too low, the gas barrier property and melt moldability under high humidity tend to be lowered, and when it is too high, the gas barrier property tends to be lowered.

  The saponification degree of the vinyl ester component in the EVOH resin is a value measured based on JIS K6726 (however, the EVOH resin is a solution uniformly dissolved in water / methanol solvent) and is usually 90 to 100 mol%, preferably It is 95-100 mol%, Most preferably, it is 99-100 mol%. When the degree of saponification is too low, gas barrier properties, thermal stability, moisture resistance and the like tend to decrease.

  Further, the melt flow rate (MFR) (210 ° C., load 2,160 g) of the EVOH resin is usually 0.5 to 100 g / 10 minutes, preferably 1 to 50 g / 10 minutes, particularly preferably 3 to 35 g. / 10 minutes. When the MFR is too large, the film forming property tends to be unstable, and when it is too small, the viscosity becomes too high and melt extrusion tends to be difficult.

  The EVOH resin used in the present invention may contain an ethylene structural unit, a vinyl alcohol structural unit (including an unsaponified vinyl ester structural unit), and a structural unit derived from a comonomer shown below. Good. Examples of the comonomer include α-olefins such as propylene, isobutene, α-octene, α-dodecene, α-octadecene; 3-buten-1-ol, 4-penten-1-ol, 3-butene-1, 2- Hydroxy group-containing α-olefins such as diols and hydroxy-containing α-olefin derivatives such as esterified products and acylated products thereof; unsaturated carboxylic acids or salts thereof, partial alkyl esters, fully alkyl esters, nitriles, amides or anhydrides; Examples thereof include unsaturated sulfonic acid or a salt thereof; vinyl silane compound; vinyl chloride; styrene.

  Furthermore, “post-modified” EVOH-based resins such as urethanization, acetalization, cyanoethylation, oxyalkyleneation, and the like can also be used.

In particular, an EVOH resin obtained by copolymerizing a hydroxy group-containing α-olefin is preferable in terms of good secondary moldability, and among them, an EVOH resin having a 1,2-diol in the side chain is preferable.
Such EVOH resin having 1,2-diol in the side chain contains 1,2-diol structural units in the side chain. The 1,2-diol structural unit is specifically a structural unit represented by the following structural unit (1).

[In General Formula (1), R ¹ , R ² , and R ³ each independently represent a hydrogen atom or an organic group, X represents a single bond or a bonded chain, and R ⁴ , R ⁵ , and R ⁶ represent 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, R ^{1 to} R ⁶ are all preferably hydrogen.

Moreover, X in the structural unit represented by the general formula (1) is typically a single bond.
In addition, a bond chain may be used as long as the effect of the present invention is not inhibited. Such a bonding chain is not particularly limited, but other than hydrocarbon chains such as alkylene, alkenylene, alkynylene, phenylene, naphthylene (these hydrocarbons may be substituted with halogen such as fluorine, chlorine, bromine, etc.), _{-O -, - (CH 2 O} ) m -, - (OCH 2) m -, - (CH 2 O) mCH 2 - structure containing an ether binding site, such as, -CO -, - COCO -, - CO ( _{CH 2) mCO -, - CO} (C 6 H 4) CO- structure containing a carbonyl group such as, -S -, - CS -, - SO -, - SO 2 - structure containing a sulfur atom, such as, -NR -, - CONR -, - NRCO -, - CSNR -, - NRCS -, - structure comprising NRNR- such as nitrogen atoms, -HPO ₄ - structure containing a hetero atom such as structure containing a phosphorus atom, such as, -Si (OR) _2- , -OSi (OR) _2- , -OSi (OR) 2O- structure containing silicon atoms such _{as, -Ti (OR) 2 -,} - OTi (OR) 2 -, - OTi (OR) 2 O- and the like structure containing titanium atoms, -Al ( OR)-, -OAl (OR)-, -OAl (OR) O-, and the like include structures containing metal atoms such as structures containing aluminum atoms. R is independently an arbitrary substituent, preferably a hydrogen atom or an alkyl group, and m is a natural number, usually 1 to 30, preferably 1 to 15, and more preferably 1 to 10. . Among them, —CH 2 OCH 2 — and a hydrocarbon chain having 1 to 10 carbon atoms are preferable from the viewpoint of stability during production or use, and further, a hydrocarbon chain having 1 to 6 carbon atoms, particularly 1 carbon atom. Is preferred.

  The most preferable structure in the 1,2-diol structural unit represented by the general formula (1) is one in which R1 to R6 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.

  In particular, when the 1,2-diol structural unit represented by the general formula (1) is contained, the content thereof is usually 0.1 to 20 mol%, further 0.1 to 15 mol%, and particularly preferably 0.1. The thing of 1-10 mol% is preferable.

  In addition, the EVOH resin used in the present invention may be a mixture with other different EVOH resins. Examples of such other EVOH resins include 1,2-diol structural units represented by the general formula (1). Examples thereof include those having different contents, those having different saponification degrees, those having different polymerization degrees, and those having different other copolymerization components.

In the present invention, the EVOH resin contains an alkali metal. Hereinafter, the EVOH resin composition containing such an alkali metal will be described.
[Alkali metal]
Examples of the alkali metal used in the present invention include sodium and potassium. Among these, sodium is preferable from the viewpoint of various physical properties such as thermal stability during melt molding.

  The content of the alkali metal is 5 to 1000 ppm, preferably 10 to 400 ppm, particularly preferably 50 to 250 ppm, particularly preferably 100 to 200 ppm in terms of metal based on the EVOH resin. If the content is too small, the effect of improving the piercing strength tends to be insufficient, while if the content is too large, a uniform film or sheet tends to be not obtained during film formation.

  The alkali metal content is determined by atomic absorption spectrophotometry (atomic absorption photometer manufactured by Hitachi, Ltd.) after ashing EVOH resin pellets or EVOH resin composition pellets in a dry state and dissolving them in an aqueous hydrochloric acid solution. Measurement is performed, and the content of alkali metal (Na) can be quantified using the ratio of absorbance to the standard solution.

The method of adding an alkali metal to the EVOH resin is not particularly limited, and i) contacting the porous precipitate of the EVOH resin (A) having a water content of 20 to 80% by weight with an aqueous solution of an additive containing an alkali metal. And ii) adding an additive containing an alkali metal to a uniform EVOH resin solution (water / alcohol solution, etc.) and then extruding it into a coagulating solution in a strand form Then, the obtained strand is cut into pellets and further dried; iii) The EVOH resin and the additive containing an alkali metal are mixed together and then melt-kneaded with an extruder or the like; iv ) During the production of EVOH resin, the alkali (sodium hydroxide, potassium hydroxide, etc.) used in the saponification process is neutralized with acids such as acetic acid and phosphoric acid, And a method like or to adjust the water washing treatment the amount of alkali metal salt.
Here, examples of the additive containing the alkali metal include alkali metal salts (sodium, potassium, etc.) of organic acids such as acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, and behenic acid. Salts; or alkali metal salts (sodium, potassium, etc.) of inorganic acids such as sulfuric acid, sulfurous acid, carbonic acid, phosphoric acid and boric acid.
In order to obtain the effects of the present invention more remarkably, the methods i) and ii), which are excellent in the dispersibility of the additive, are preferred, and the method i) is particularly preferred from the viewpoint of the solubility of the additive.

[Other resins]
The EVOH resin used in the present invention may be a composition in which the base resin is an EVOH resin.
Therefore, in this EVOH resin composition, in addition to the EVOH resin, other thermoplastic resins may be usually contained at 30% by weight or less with respect to the EVOH resin.

  Specific examples of the other thermoplastic resins include linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ionomer, and ethylene-propylene copolymer. , Ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, ethylene-acrylic acid ester copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer Polyolefin resins in a broad sense such as polymers, polybutenes, polypentenes or other olefins alone or copolymers, polycyclic olefins, or those olefins alone or copolymers grafted with unsaturated carboxylic acids or esters thereof, Polystyrene resin, polyester, polyamide, copolymer polyamid , Polyvinyl chloride, polyvinylidene chloride, acrylic resin, vinyl ester resin, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, a thermoplastic resin such as chlorinated polypropylene.

  Thermoplastic resins are usually made from petroleum-derived raw materials such as naphtha, but are derived from natural gas-derived raw materials such as shale gas, sugar, starch, sugar and other ingredients contained in sugarcane, sugar beet, corn, potato, etc. Plant-derived raw materials purified from components such as cellulose contained in rice, wheat, millet, grass plants and the like may be used.

  In particular, when the multilayer structure of the present invention is used as a packaging material for foods, a polyamide-based resin is used in that the EVOH resin layer is prevented from being eluted at the end of the packaging material after the hot water treatment of the packaging material. It is preferable to mix.

[Other additives]
In addition to the above components, the EVOH resin of the present invention includes, if necessary, ethylene glycol, glycerin, hexane as long as the effects of the present invention are not impaired (eg, less than 5% by weight of the total resin composition). Plasticizers such as aliphatic polyhydric alcohols such as diols; saturated aliphatic amides (such as stearic acid amides), unsaturated fatty acid amides (such as oleic acid amides), bis fatty acid amides (such as ethylene bisstearic acid amide), Lubricants such as 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); thermal stabilizers; antiblocking agents; antioxidants; coloring agents; antistatic agents; Insoluble inorganic salt (for example, hydrotalcite); filler (for example, inorganic filler); crystal nucleus (For example, talc, kaolin, etc.); surfactants, waxes; dispersants (for example, calcium stearate, stearic acid monoglyceride, etc.); conjugated polyene compounds, aldehyde compounds (for example, unsaturated aldehydes such as crotonaldehyde, etc.) An agent can be appropriately blended.

  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; or inorganic acids such as sulfuric acid, sulfurous acid, carbonic acid, phosphoric acid, boric acid, or alkalis thereof Additives such as metal salts (sodium, potassium, etc.), alkaline earth metal salts (calcium, magnesium, etc.) and salts such as zinc may be added. Of these, it is particularly preferable to add boron compounds, acetates and phosphates including acetic acid, boric acid and salts thereof.

Next, the cyclic olefin resin layer (γ) will be described.
<Cyclic olefin resin layer (γ)>
The cyclic olefin-based resin layer having a glass transition point of 85 to 130 ° C. in the present invention is mainly composed of a cyclic olefin having a glass transition point of 85 to 130 ° C.
The cyclic olefin-based resin used in the multilayer structure of the present invention is a polymer having a cyclic olefin structure in the main chain and / or side chain. For example, JP 2003-103718 A and JP 5-17776 A are disclosed. , A known resin as described in JP-T-2003-504523. Such a cyclic olefin resin is an amorphous resin.

［式中、ｎは１以上の整数である。］

［式中、ｎは１以上の整数である。］ When a monomer having an unsaturated bond in the cyclic olefin structure is used (for example, norbornene or the like), a polymer having a cyclic olefin structure in the main chain as exemplified in the following chemical formula (2) is obtained. When a monomer having an unsaturated bond is used (for example, vinyl norbornene or the like), a polymer having a cyclic olefin structure in the side chain as shown in the following chemical formula (3) is obtained.

[Wherein n is an integer of 1 or more. ]

[Wherein n is an integer of 1 or more. ]

  Among these, a polymer having a cyclic olefin structure in the main chain is preferable from the viewpoints of weather resistance, moisture resistance and the like.

  The cyclic olefin-based resin includes a homopolymer of a cyclic olefin monomer and a copolymer with another monomer copolymerizable with the cyclic olefin monomer described later. Further, a hydrogenated product of a polymer having a cyclic olefin structure having an alicyclic structure in the main chain and / or side chain is also included.

  The number of carbon atoms constituting the cyclic olefin structure is not particularly limited, but is preferably 4 to 30, more preferably 5 to 20, and even more preferably 5 to 15. When the number of carbon atoms is too large or too small, moisture resistance and molding processability tend to decrease.

  Cyclic olefin monomers are broadly classified into, for example, monomers having an unsaturated bond in the cyclic olefin structure and monomers having an unsaturated bond outside the cyclic olefin structure. Specific examples of monomers having an unsaturated bond in the cyclic olefin structure include bicyclo [2,2,1] hept-2-ene (norbornene) derivatives and tricyclo [4,3,0,12,5] deca-3. , 7-diene (common name: dicyclopentadiene) derivative, tricyclo [4.3.0.12,5] -3-decene derivative, tricyclo [4.3.0.12,5] -3-undecene derivative, tetracyclo [4.4.0.12, 5.17,10] -dodec-3-ene (common name: tetracyclododecene) derivative, hexacyclo [6.6.1.13,6.110,13.02,7.09,14] -4-heptadecene derivative, octacyclo [8.8.0.12,9.14,7.111 , 18.113,16.03,8.012,17] -5-docosene derivatives, pentacyclo [6.6.1.13,6.02,7.09,14] -4-hexadecene derivatives, heptacyclo-5-eicosene derivatives, heptacyclo-5-heneicosene derivatives, pentacyclo [6.5 .1.13,6.02,7.09,13] -4-pentadecene induction And pentacyclo 4,10 penta octadecadienoic derivatives and the like can be mentioned.

  Examples of the bicyclo [2,2,1] hept-2-ene (norbornene) derivative include bicyclo [2,2,1] hept-2-ene (common name: norbornene), 5-methyl-bicyclo [2, 2,1] hept-2-ene, 5,5-dimethyl-bicyclo [2,2,1] hept-2-ene, 5-ethyl-bicyclo [2,2,1] hept-2-ene, 5- Butyl-bicyclo [2,2,1] hept-2-ene, 5-hexyl-bicyclo [2,2,1] hept-2-ene, 5-octyl-bicyclo [2,2,1] hept-2-ene Ene, 5-octadecyl-bicyclo [2,2,1] hept-2-ene, 5-ethylidene-bicyclo [2,2,1] hept-2-ene, 5-methylidene-bicyclo [2,2,1] Hept-2-ene, 5-vinyl-bicyclo [2,2,1] hept- -Ene, 5-propenyl-bicyclo [2,2,1] hept-2-ene, 5-methoxy-carbonyl-bicyclo [2,2,1] hept-2-ene, 5-cyano-bicyclo [2,2 , 1] hept-2-ene, 5-methyl-5-methoxycarbonyl-bicyclo [2,2,1] hept-2-ene; 5-methoxycarbonylbicyclo [2,2,1] hept-2-ene, 5-ethoxycarbonylbicyclo [2,2,1] hept-2-ene, 5-methyl-5-methoxycarbonylbicyclo [2,2,1] hept-2-ene, 5-methyl-5-ethoxycarbonylbicyclo [ 2,2,1] hept-2-ene, bicyclo [2,2,1] hept-5-enyl-2-methylpropionate, bicyclo [2,2,1] hept-5-enyl-2-methyl Octanate, 5 -Hydroxymethylbicyclo [2,2,1] hept-2-ene, 5,6-di (hydroxymethyl) bicyclo [2,2,1] hept-2-ene, 5-hydroxy-i-propylbicyclo [2] , 2,1] hept-2-ene, 5,6-dicarboxybicyclo [2,2,1] hept-2-ene; 5-cyanobicyclo [2,2,1] hept-2-ene, bicyclo [ 2,2,1] hept-2-ene-5,6-dicarboxylic imide; 5-cyclopentyl-bicyclo [2,2,1] hept-2-ene, 5-cyclohexyl-bicyclo [2,2,1] Examples include hept-2-ene, 5-cyclohexenylbicyclo [2,2,1] hept-2-ene, and 5-phenyl-bicyclo [2,2,1] hept-2-ene.

The tricyclo [4,3,0,12,5] deca-3,7-diene derivative includes tricyclo [4,3,0,12,5] deca-3,7-diene (common name: dicyclopentadiene). Tricyclo [4,3,0,12,5] dec-3-ene; tricyclo [4,3,0,12,5] undeca-3,7-diene; tricyclo [4,3,0,12,5 ] Undeca-3,8-diene; tricyclo [4,3,0,12,5] undec-3-ene.
Tricyclo [4.3.0.12,5] -3-decene derivatives include tricyclo [4.3.0.12,5] -3-decene, 2-methyl-tricyclo [4.3.0.12,5] -3-decene, 5- And methyl-tricyclo [4.3.0.12,5] -3-decene.
Tricyclo [4.3.0.12,5] -3-undecene derivatives include tricyclo [4.3.0.12,5] -3-undecene and 10-methyltricyclo [4.3.0.12,5] -3-undecene.

  And tetracyclo [4.4.0.12,5.17,10] -dodec-3-ene (common name: tetracyclododecene) derivatives, specifically 8-methyltetracyclo [[4.4.0.12,5.17,10]- Dodec-3-ene, 8-ethyltetracyclo [4.4.0.12,5.17,10] -dodec-3-ene, 8-methylidenetetracyclo [4.4.0.12,5.17,10] -dodec-3-ene, 8 Ethylidenetetracyclo [4.4.0.12,5.17,10] -dodec-3-ene, 8-vinyltetracyclo [4.4.0.12,5.17,10] -dodec-3-ene, 8-propenyl-tetracyclo [4.4.0.12 , 5.17,10] -dodec-3-ene, 8-methoxycarbonyltetracyclo [4.4.0.12,5.17,10] -dodec-3-ene, 8-methyl-8-methoxycarbonyltetracyclo [4.4.0.12,5.17 , 10] -dodec-3-ene, 8-hydroxymethyltetracyclo [4.4.0.12,5.17,10] -dodec-3- Ene, 8-carboxytetracyclo [4.4.0.12,5.17,10] -dodec-3-ene; 8-cyclopentyl-tetracyclo [4.4.0.12,5.17,10] -dodec-3-ene, 8-cyclohexyl-tetracyclo [ 4.4.0.12,5.17,10] -dodec-3-ene, 8-cyclohexenyl-tetracyclo [4.4.0.12,5.17,10] -dodec-3-ene, 8-phenyl-cyclopentyl-tetracyclo [4.4.0.12,5.17 , 10] -dodec-3-ene.

Hexacyclo [6.6.1.13,6.110,13.02,7.09,14] -4-heptadecene derivatives include hexacyclo [6.6.1.13,6.110,13.02,7.09,14] -4-heptadecene, 12-methylhexacyclo [6.6.1.13 , 6.110,13.02,7.09,14] -4-heptadecene, 1,6,10-trimethyl-hexacyclo [6.6.1.13,6.110,13.02,7.09,14] -4-heptadecene and the like.
Octacyclo [8.8.0.12,9.14,7.111,18.113,16.03,8.012,17] -5-docosene derivatives include octacyclo [8.8.0.12,9.14,7.111,18.113,16.03,8.012,17] -5-docosene, 15 -Methyl-octacyclo [8.8.0.12,9.14,7.111,18.113,16.03,8.012,17] -5-docosene.

Pentacyclo [6.6.1.13,6.02,7.09,14] -4-hexadecene derivatives include pentacyclo [6.6.1.13,6.02,7.09,14] -4-hexadecene, 1,3-dimethylpentacyclo [6.6.1.13,6.02 , 7.09,14] -4-hexadecene, 15,16-dimethylpentacyclo [6.6.1.13,6.02,7.09,14] -4-hexadecene.
As heptacyclo-5-eicosene derivatives, heptacyclo- [8.7.0.12,9.14,7.111,17.03,8.012,16] -eicosene, heptacyclo-5-heneicosene derivatives include Heptacyclo- [8.8.0.12, 9.14,7.111,18.03,8.012,17] -heneicosen.

Pentacyclo [6.5.1.13,6.02,7.09,13] -4-pentadecene derivatives include pentacyclo [6.5.1.13,6.02,7.09,13] -4-pentadecene, 1,3-dimethylpentacyclo [6.5.1.13,6.02 , 7.09,13] -4-pentadecene, 1,6-dimethylpentacyclo [6.5.1.13,6.02,7.09,13] -4-pentadecene.
Examples of the pentacyclo-4,10-pentadecadiene derivative include pentacyclo [6,5,1,13,6,02,7,09,13] pentadeca-4,10-diene.

  Specific examples of the monomer having an unsaturated bond outside the cyclic olefin structure include vinyl norbornane and vinyl norbornene.

These cyclic olefin monomers may be used alone or in combination of two or more. Among these, bicyclo [2,2,1] hept-2-ene (norbornene) derivatives are preferable from the viewpoint of market availability, and bicyclo [2,2,1] hept-2-ene (norbornene) is particularly preferable. is there.
When two or more of these cyclic olefinic monomers are used in combination, the content of the bicyclo [2,2,1] hept-2-ene (norbornene) derivative with respect to the total cyclic olefinic monomer is 10% by weight or more. From the viewpoint of weather resistance, it is preferable.

The other monomer copolymerizable with the cyclic olefin monomer is not particularly limited as long as it is copolymerizable with the cyclic olefin monomer.
Examples include acyclic olefins, specifically ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, and 3-ethyl-1. -Pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene and the like α-olefin having 2 to 20 carbon atoms; 1,4-hexadiene, Non-conjugated dienes such as 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,7-octadiene and the like can be mentioned.
These copolymerizable monomers can be used alone or in combination of two or more.
Of these, α-olefins having 2 to 20 carbon atoms are preferable from the viewpoint of reactivity and versatility, more preferably α-olefins having 2 to 4 carbon atoms, and ethylene is particularly preferable.

When the cyclic olefin-based resin is obtained by copolymerizing such another copolymerizable monomer, the proportion of the structural unit having a cyclic olefin structure is usually 1 to 99 mol%, preferably 20 to 70 mol%. And particularly preferably 40 to 50 mol%. When the ratio of the repeating unit having a cyclic olefin structure is too small, the weather resistance and heat resistance may be insufficient. Moreover, when too large, there exists a tendency for melt moldability to fall.
That is, the content of the other copolymerizable monomer is usually 1 to 99 mol%, preferably 10 to 90 mol%, particularly preferably 30 to 70 mol%.

Some of the above monomers leave a double bond, and when such a double bond remains, the cyclic olefin resin may be colored. Therefore, it is preferable to use the cyclic olefin resin after hydrogenation.
When the cyclic olefin resin used in the present invention is hydrogenated, the polymer obtained as described above is obtained by a method of hydrogenating with hydrogen in the presence of a hydrogenation catalyst according to a conventional method. Can do.
The hydrogenation rate is usually preferably 95% or more and 98% or more, and more preferably 99% or more, from the viewpoint of weather resistance and moisture resistance. Here, the hydrogenation rate is represented by the ratio of the number of moles of hydrogenated matter to the total number of moles of carbon-carbon double bonds before hydrogenation.

The glass transition point (Tg) of the cyclic olefin resin used in the present invention is a value measured according to JIS K 7121 and is 85 to 130 ° C, preferably 100 to 120 ° C, particularly preferably 105 to 105 ° C. 115 ° C.
If the glass transition temperature is too low, the resin tends to fuse during the hot water treatment. On the other hand, if it is too high, water vapor that has entered during the hot water treatment is difficult to be released from the gas barrier layer, and the oxygen permeability tends to deteriorate.
The greatest feature of the present invention is to use a cyclic olefin resin having a specific glass transition point as a main component.

  The molecular weight of the cyclic olefin resin is appropriately selected depending on the purpose of use, but the weight in terms of polyisoprene measured by gel permeation chromatography method of cyclohexane solution (toluene solution when polymer resin is not dissolved) The average molecular weight is usually preferably 5,000 to 500,000 and 8,000 to 200,000, more preferably 10,000 to 100,000. If the weight average molecular weight is too large, the processing temperature may become high and processing may be difficult. If it is too small, the strength of the multilayer structure tends to be insufficient.

  The melt flow rate (MFR) of the cyclic olefin-based resin is usually 0.5 to 100 g / 10 minutes, more preferably 5 to 50 g / 10 minutes in the measurement based on JIS-K7210 (230 ° C., 2160 g load). If the melt flow rate is too small, the molding temperature tends to be higher, resulting in molding failure. If it is too large, molding defects such as burrs tend to occur during molding.

The density of the cycloolefin resin (kg / m ^3), in the measurement based on ISO1183, usually 700~1300kg / m ^3, more preferably 900~1100kg / m ^3, particularly preferably 950~1050kg / m ^3.

These cyclic olefin resins can be used alone or in combination of two or more.
The resin is commercially available, for example, as “TOPAS (registered trademark)” manufactured by Polyplastics, “Apel (registered trademark)” manufactured by Mitsui Chemicals, Inc.

When two or more kinds of cyclic olefin resins are used in combination, the cyclic olefin resin having a glass transition point (Tg) of 85 to 130 ° C. is a main component, and the content is usually 60 to 100% by weight, Preferably it is 70-100 weight%, More preferably, it is 80-100 weight%, More preferably, it is 90-100 weight%.
Most preferably, the glass transition point (Tg) consists only of a cyclic olefin resin having a temperature of 85 to 130 ° C.

  As the cyclic olefin resin used in the present invention, for example, an unsaturated carboxylic acid-modified cyclic olefin resin obtained by modifying an unsaturated carboxylic acid or a derivative thereof into the above cyclic olefin resin by a known method may be used.

Examples of such modification include known methods such as a method of modifying a cyclic olefin resin by mixing an unsaturated carboxylic acid or a derivative thereof, a method of modifying by copolymerization, and a method of graft modification.
Examples of the mixing method include a melt mixing method and a solution mixing method. As a copolymerization method, a method of copolymerizing the unsaturated carboxylic acid or a derivative thereof to a cyclic olefin resin by a known method is general. Examples of the graft modification method include a method of dispersing or dissolving a cyclic olefin resin and an unsaturated carboxylic acid or a derivative thereof in an organic solvent and reacting by heating and stirring, or a cyclic olefin without using a solvent. There is a method in which a resin and an unsaturated carboxylic acid or derivative thereof are reacted by melting and kneading with an extruder. The latter is simpler and more economical.

Examples of the unsaturated carboxylic acid include unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, and nadic acid TM (endocis). -Unsaturated dicarboxylic acids such as bicyclo [2,2,1] hept-5-ene-2,3-dicarboxylic acid).
Examples of the unsaturated carboxylic acid derivatives include unsaturated carboxylic acid anhydrides, unsaturated carboxylic acid halides, unsaturated carboxylic acid amides, unsaturated carboxylic acid imides, and unsaturated carboxylic acid ester compounds. . Specific examples include maleenyl chloride, maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate, glycidyl acrylate and glycidyl methacrylate. These unsaturated carboxylic acids or derivatives thereof can be used alone or in combination.
Especially, carbon number of unsaturated carboxylic acid or its derivative (s) is 3-20 normally from the point of handleability, Preferably it is 3-15, Most preferably, it is 3-10. Furthermore, the melting point of the unsaturated carboxylic acid or derivative thereof is usually 0 to 200 ° C., preferably 30 to 100 ° C., particularly preferably 40 to 80 ° C. from the viewpoint of handleability.

In addition, the cyclic olefin resin may contain other resins and various compounding agents at 10% by weight or less based on the total amount of the cyclic olefin resin as necessary.
Various compounding agents include commonly used compounding agents such as anti-aging agents, stabilizers, flame retardants, plasticizers, crystal nucleating agents, hydrochloric acid absorbents, antistatic agents, inorganic fillers, lubricants, anti-blocking agents and the like. Can be mentioned.
Further, a light-shielding property may be imparted by blending a colorant, an ultraviolet absorber (for example, benzophenone series, benzotriazole series, acrylate series, salicylate series, etc.).

Further, the acid-modified olefin elastomer layer (β) used as an adhesive layer between the cyclic olefin resin layer (γ) and the EVOH resin layer (α) will be described.
<Acid-modified olefin elastomer layer (β)>
The acid-modified olefin elastomer used in the present invention is an olefin having a thermoplastic property composed of a polyolefin component (A) as a hard segment (hard phase) and an aliphatic rubber component (B) as a soft segment (soft phase). And a composition containing at least one of component (A) and component (B) modified with an unsaturated carboxylic acid or an anhydride thereof.

  The polyolefin component of component (A) in the present invention is a hard segment (hard phase) in the composition, and nonpolar α-olefin monomers such as ethylene, propylene, butene-1, and pentene-1 are polymerized in a conventional manner. The crystalline polymer obtained is typically a polyethylene resin (polyethylene and its copolymer), a polypropylene resin (polypropylene and its copolymer), polybutene, etc., but after retorting From the viewpoint of maintaining the adhesive property, polypropylene resin is preferred.

  Examples of the component (A) polypropylene resin include propylene homopolymer (polypropylene), copolymers of propylene and α-olefins having 2 to 8 carbon atoms other than propylene (one or more). It is done. Any one or two or more of these may be used in combination, but a propylene homopolymer (polypropylene) is preferred. In the case of a copolymer, the α-olefin having 2 to 8 carbon atoms includes ethylene, butene-1, 3-methylbutene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1. Among these, ethylene is preferable. In the case of a copolymer, the propylene content is preferably 85% by weight or more.

  The aliphatic rubber component of component (B) in the present invention is a soft segment (soft phase) in the composition, and is a copolymer rubber of two or more olefins or a non-conjugated diene further co-polymerized with the copolymer rubber. It is composed of polymerized copolymer rubber. Examples of the two or more olefins include any one selected from the group consisting of ethylene, propylene, butene-1, 3-methylbutene-1, pentene-1, 4-methylpentene-1, hexene-1, and octene-1. Of these, two or more are preferred, and of these, two or more selected from at least ethylene and propylene are particularly preferred. Most preferred are ethylene and propylene. Examples of the non-conjugated diene include 1,4-hexadiene, dicyclopentadiene, methylene norbornene, ethylidene norbornene, propenyl norbornene, cyclooctadiene, methyltetrahydroindene, and the like. Two or more are used.

  The olefin elastomers used in the present invention are classified into three forms: (1) mixed type, (2) dynamic cross-linking type, and (3) polymerization type.

(1) The mixed type is a mixture of component (A) and component (B). In the olefin elastomer of the mixture, component (B) is an organic peroxide before mixing with component (A). Further, it may be partially crosslinked using a crosslinking agent such as a phenol-based crosslinking agent, sulfur, an oxime compound, or a polyamine compound. The crosslinking agent is preferably an organic peroxide such as di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy). ) Hexin-3, t-butylperoxybenzoate, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexyne-3, n-butyl-4,4-di (t-butylperoxy) ) Valerate, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylbenzoate, t-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, benzoyl peroxide, etc. Can use any 1 type (s) or 2 or more types.
(1) Specific examples of the mixed type olefin elastomer include, for example, Thermolan (Mitsubishi Chemical Co., Ltd.), Miralastomer (Mitsui Chemicals Co., Ltd.), Espolex TPE (Sumitomo Chemical Co., Ltd.), etc. Can be mentioned.

(2) The dynamic cross-linking type is obtained by dynamically heat-treating component (A) and component (B) in the presence of an organic peroxide to partially cross-link component (B).
Here, the dynamic heat treatment means that the component (A), the component (B) and the organic peroxide are mixed using a kneading apparatus such as a mixing roll, a kneader Banbury mixer, a Brabender blast graph, a single or twin screw extruder. It is to knead the product in a molten state, and the kneading conditions are usually 100 ° C. to 350 ° C., preferably 120 ° C. to 280 ° C., 0.2 minutes to 30 minutes, preferably 0.5 minutes to For 20 minutes. In addition, the organic peroxide herein includes the specific compounds exemplified above (di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di- (T-butylperoxy) hexyne-3, t-butylperoxybenzoate, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexyne-3, n-butyl-4,4-bis (T-Butylperoxy) valerate, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylbenzoate, t-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, benzoyl peroxide) 1 type (s) or 2 or more types are used.
(2) Specific examples of the dynamically crosslinked olefin-based elastomer include, for example, Santoprene (manufactured by ExxonMobil Chemical Co.), Sarlink (manufactured by Toyobo Co., Ltd.), and the like.

(3) The polymerization type is obtained by polymerizing component (A) and component (B) stepwise in the same polymerization tank by multi-stage polymerization, and the polymerization type olefin elastomer is subjected to organic peroxidation after multi-stage polymerization. The component (B) may be partially crosslinked by heat treatment dynamically in the presence of the product. Here, the dynamic heat treatment means that the polymerization product (component (A), component (B)) and the crosslinking agent are melt-kneaded by the kneading apparatus. The kneading conditions in this case are the same as described above (usually 100 ° C. to 350 ° C., preferably 120 ° C. to 280 ° C., 0.2 minutes to 30 minutes, preferably 0.5 minutes to 20 minutes). Is preferred.
(3) Specific examples of the polymerization type olefin elastomer include, for example, Newcon (manufactured by Nippon Polypro Co., Ltd.), Zelas (manufactured by Mitsubishi Chemical Corporation), Prime TPO (manufactured by Mitsui Chemicals, Inc.) and the like. Can be mentioned.

  In the present invention, from the viewpoint of maintaining the adhesiveness after the retort treatment, (3) a polymerization type olefin elastomer having excellent retort resistance is preferable.

  In the present invention, at least one of component (A) and component (B) is unsaturated so that the content of unsaturated carboxylic acid or the like is 0.01% by weight or more based on the total amount of these two components. It is necessary to contain one modified with carboxylic acid or the like.

  The method for modifying the thermoplastic olefin elastomer resin composed of the polyolefin component (A) as the hard segment and the aliphatic rubber component (B) as the soft segment is not particularly limited. For example, the component (A) And / or an unsaturated carboxylic acid or the like and a radical generator are added to a solution obtained by dissolving the component (B) in an organic solvent, and the temperature is usually 60 to 350 ° C., preferably 80 to 190 ° C., for 0.5 to 15 hours. Preferably, it can be carried out by reacting for 1 to 10 hours.

  In addition, as another method, using an extruder or the like, the component (A) and / or the component (B) can be modified by reacting with an unsaturated carboxylic acid or the like. As the reaction conditions in this case, the reaction temperature is usually higher than the melting point of these resins, for example, 170 to 280 ° C., and the reaction time is usually about 0.5 to 10 minutes.

Whichever modification method is employed, it is preferable to carry out the modification reaction in the presence of a radical generator in order to efficiently react the above-described unsaturated carboxylic acid for modification and the like. As the radical generator, an organic peroxide is preferably used.
For example, benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (peroxybenzoate) hexyne-3, 1,4-bis (t-butylperoxy) Isopropyl) benzene, lauroyl peroxide, t-butyl peracetate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (t-butylperoxy) ) Dialkyl peroxides such as hexane, t-butylperoxybenzoate, t-butylperoxyphenyl acetate, t-butylperoxyisobutyrate, t-butylperoxy-sec-octoate, t-butylperoxypivalate, cumylperoxypivalate, Organic Oxy esters, diacyl peroxides, or the like is used.

  Among these, diacyl peroxides such as benzoyl peroxide and dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, 2,5-dimethyl-2 Dialkyl peroxides such as 1,5-di (t-butylperoxy) hexane and 1,4-bis (t-butylperoxyisopropyl) benzene are preferred.

  The radical generator is usually used in a proportion of 0.001 to 10 parts by weight per 100 parts by weight of the component (A) and / or component (B) before modification.

The content of the unsaturated carboxylic acid and the like in the composition thus obtained is 0.01% by weight or more, preferably 0.01 to 10% by weight, preferably 0.02 to 3% by weight. Part is particularly preferred. If the amount is too small, the adhesion tends to be inferior. On the other hand, if the amount is too large, the physical properties of the olefin-based elastomer tend to be impaired.
The content of the unsaturated carboxylic acid or the like can be measured by an infrared absorption spectrum analysis method using a calibration curve method.

The melting point of the acid-modified olefin elastomer is usually 130 ° C to 200 ° C, preferably 140 ° C to 180 ° C, particularly preferably 150 ° C to 170 ° C. If the melting point is too low, delamination may occur due to adhesion loss after retorting. On the other hand, if the melting point is too high, delamination may occur due to insufficient adhesion between the EVOH resin and the cyclic olefin resin. is there.
In addition, melting | fusing point in this invention shows the melting temperature value (based on JISK7121) at the temperature increase rate of 10 degrees C / min by DSC (differential scanning calorimeter).

The heat of fusion of the acid-modified olefin elastomer is usually 1 to 50 J / g, preferably 2 to 40 J / g, and particularly preferably 5 to 20 J / g. If the heat of fusion is too low, delamination may occur due to adhesion loss after retorting. On the other hand, if the heat of fusion is too high, delamination may occur due to insufficient adhesion with the cyclic olefin resin. .
Here, the heat of fusion indicates a heat of fusion value (according to JIS K7122) at a heating rate of 10 ° C./min by DSC (differential scanning calorimeter).

  The melt flow rate (MFR) of the acid-modified olefin elastomer is usually 1 to 100 g / 10 min, more preferably 2 to 30 g / 10 min in the measurement based on JIS-K7210 (230 ° C., 2160 g load). If the melt flow rate is too small, the molding temperature tends to be higher and the molding tends to be defective, whereas if too high, molding defects such as burrs tend to occur during molding.

  In the present invention, in addition to the above essential components, a compounding agent used in a normal polyolefin composition may be added as necessary within a range not impairing the effects of the present invention. Examples of such a compounding agent include a heat stabilizer, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a neutralizer, a rust inhibitor, and a pigment.

  The acid-modified olefin elastomer is commercially available, for example, as “Zeras (registered trademark)” manufactured by Mitsubishi Chemical Corporation.

<EVOH resin layer (α) / acid-modified olefin elastomer layer (β) / cyclic olefin resin layer (γ)>
Subsequently, the multilayer structure of the present invention will be described.

  The multilayer structure of the present invention has a cyclic structure having a specific glass transition point on at least one surface of an EVOH resin layer (α) containing a specific amount of alkali metal via an acid-modified olefin elastomer layer (β). It is a multilayer structure including a laminated unit provided with an olefin resin layer (γ).

  In the multilayer structure of the present invention, it is sufficient that at least one laminated unit having the above configuration is included, but two or more laminated units may be included. When two or more are included, another resin layer may be interposed between the laminated units.

As a lamination method for obtaining the above-mentioned lamination unit, it can be carried out by a known method. For example, a method of melt extrusion laminating an acid-modified olefin elastomer layer (β) or a cyclic olefin resin layer (γ) to an alkali metal-containing EVOH resin film or sheet, and conversely an acid-modified olefin elastomer layer (β) A method of melt extrusion laminating an alkali metal-containing EVOH resin to a cyclic olefin resin layer (γ), a method of co-extruding an alkali metal-containing EVOH resin and an acid-modified olefin elastomer or a cyclic olefin resin, an acid-modified olefin elastomer layer Examples thereof include a method of removing the solvent after coating a solution of an alkali metal-containing EVOH resin on (β) or the cyclic olefin-based resin layer (γ).
Among these, the co-extrusion method is preferable from the viewpoint of cost and environment.

<Other layers>
In the multilayer structure of the present invention, at least one or more other layers may be laminated on the upper surface or the lower surface of the laminated unit.
(1) Other base resin layer (δ)
By further laminating another base material layer (δ) on the laminated unit of EVOH resin layer (α) / acid-modified olefin elastomer layer (β) / cyclic olefin resin layer (γ), Other functions can be given.

The material used for the other base resin layer (δ) is preferably a thermoplastic resin other than the EVOH resin (hereinafter referred to as “other base resin”). Moreover, you may use the recycled material obtained by remelt-molding the edge part, defective goods, etc. which generate | occur | produce in the process of manufacturing this multilayer structure. The recycled material includes a molten mixture of an EVOH resin layer (α), an acid-modified olefin elastomer layer (β), a cyclic olefin resin layer (γ), and another base resin layer (δ).
Furthermore, when the adhesiveness with the other base resin layer (δ) and the re-sacryl layer (R) is insufficient, an adhesive layer may be appropriately interposed between the layers.

The number of layers of the multilayer structure is generally 3 to 15, preferably 5 to 10 in total.
Among the multilayer structures as described above, a structure in which another base material (δ) is laminated on the unit of EVOH resin layer (α) / acid-modified olefin elastomer layer (β) / cyclic olefin resin layer (γ) ( δ1 / α / β / γ, δ1 / adhesive resin layer / α / β / γ, δ2 / δ1 / adhesive resin layer / α / β / γ, δ2 / adhesive resin layer / δ1 / adhesive resin layer / α / β / γ) is preferable from the viewpoint of increasing the strength and imparting other functions. From the viewpoint of water resistance and adhesiveness, δ1 / adhesive resin layer / α / β / γ and δ2 / adhesive resin layer / δ1 / adhesive resin layer / α / β / γ are preferable.

  Examples of the “other base resin” include linear low density polyethylene, low density polyethylene, ultra low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-propylene (block and random) copolymer, ethylene -Polyethylene resins such as α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, polypropylene resins such as polypropylene and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer Polyolefins including modified olefin resins such as (unmodified) polyolefin resins such as polybutene and polypentene, and unsaturated carboxylic acid modified polyolefin resins obtained by graft-modifying these polyolefins with unsaturated carboxylic acids or esters thereof Resin, cyclic olefin resin, Iono -, Ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, polyester resin, polyamide resin (including copolymerized polyamide), polyvinyl chloride, polyvinylidene chloride, acrylic Resin, polystyrene, vinyl ester resin, polyester elastomer, polyurethane elastomer, chlorinated polyethylene, halogenated polyolefin such as chlorinated polypropylene, and aromatic or aliphatic polyketones.

Among these, it is preferable to use a cyclic olefin resin from the viewpoint of hydrophobicity.
As the cyclic olefin resin, the same cyclic olefin resin as that used for the cyclic olefin resin layer (γ) can be used.

(2) Adhesive resin layer When providing another base resin layer, an adhesive resin layer may be appropriately interposed.
As the adhesive resin, known resins can be used, and may be appropriately selected according to the type of thermoplastic resin constituting the other base resin layer. A typical example is a modified polyolefin polymer containing a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or an anhydride thereof to a polyolefin resin by an addition reaction or a graft reaction. 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 polycyclic olefin resin, maleic anhydride graft-modified polyolefin resin, and the like, and one or a mixture of two or more selected from these can be used.

  When the cyclic olefin resin is used as the “other base resin”, it is preferable to use the acid-modified olefin elastomer as the adhesive resin. Among these, for hydrothermal treatment applications, acid-modified polypropylene elastomers are desirable from the viewpoints of heat resistance and water resistance.

  In the base resin and adhesive resin, plasticizers, fillers, clays, and the like that are conventionally known within a range not impairing the gist of the present invention (for example, 30% by weight or less, preferably 10% by weight or less). Montmorillonite, etc.), colorant, antioxidant, antistatic agent, lubricant, core material, antiblocking agent, ultraviolet absorber, wax and the like.

<Manufacture of multilayer structure>
When the multilayer structure of the present invention includes at least one of the other base resin layer (δ), the recycled layer (R), and the adhesive resin layer as other layers as described above, the following is usually performed. Can be manufactured.

  i) Method of laminating by coextrusion with EVOH resin layer (α) / acid-modified olefin elastomer layer (β) / cyclic olefin resin layer (γ) units: ii) Other base resin film formed separately , A method of forming a film made of a recycled material, an adhesive resin film, a sheet, etc. by dry laminating with the above unit; iii) another base resin film formed separately, a film made of a recycled material, A unit composed of a combination of EVOH resin layer (α) / acid-modified olefin elastomer layer (β) / cyclic olefin resin layer (γ) is melted on the surface of an adhesive resin film, sheet, or the like, or an appropriate combination thereof The method of laminating by coextrusion is mentioned. Furthermore, other base resin, recycled material or adhesive solution is applied to the laminated unit consisting of EVOH resin layer (α) / acid-modified olefin elastomer layer (β) / cyclic olefin resin layer (γ). And a method of removing the solvent after that. Among these, from the viewpoint of productivity, i) a method of laminating by coextrusion together with units of EVOH resin layer (α) / acid-modified olefin elastomer layer (β) / cyclic olefin resin layer (γ) is preferable.

  In the case of coextrusion molding, the extrusion temperature of the EVOH resin composition is appropriately set in the range of usually 150 to 300 ° C (more preferably 160 to 250 ° C).

  In the present invention, the barrel temperature of the extruder means the surface temperature of the barrel of the extruder. When the barrel of the extruder has a plurality of sections and each section is set to a different temperature, the highest temperature is set as the barrel temperature.

  The obtained multilayer structure may then be 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 maintaining a tension state.

  The thickness of the multilayer structure (including the stretched one), and the thickness of the EVOH resin layer, acid-modified olefin elastomer layer, and cyclic olefin resin layer constituting the multilayer structure are the same as those of the layer structure, acid-modified olefin elastomer. The thickness of the multilayer structure (including stretched one) is usually 10 to 5000 μm, preferably 30 to 3000 μm, although it cannot be generally stated depending on the type, type of cyclic olefin resin, application and packaging form, required physical properties, etc. Especially preferably, it is 50-2000 micrometers. The EVOH resin layer is usually 1 to 500 μm, preferably 3 to 300 μm, particularly preferably 5 to 200 μm. The acid-modified olefin elastomer layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, particularly preferably 3 to 100 μm, and the cyclic olefin resin is usually 1 to 300 μm, preferably 5 to 200 μm, particularly preferably 10 ˜100 μm.

The ratio α / β between the EVOH resin layer (α) thickness and the acid-modified olefin elastomer layer (β) thickness is preferably α / β = 0.5-10. When α / β is too small, the gas barrier property is insufficient. On the other hand, when too large, sufficient adhesiveness cannot be maintained.
The ratio α / γ between the EVOH resin layer (α) thickness and the cyclic olefin resin layer (γ) thickness is preferably α / γ = 0.5-10. When α / γ is too small, the recovery rate of the gas barrier property of the EVOH resin deteriorated by the hot water treatment tends to decrease. On the other hand, when α / γ is too large, a large amount of water permeates into the laminate during the hot water treatment, causing a significant decrease in gas barrier properties and adhesive strength.

<Use of multilayer structure>
The multilayer structure of the present invention is a general food, seasoning such as mayonnaise and dressing, fermented food such as miso, fat and oil food such as salad oil, various packaging materials containers for beverages, cosmetics, pharmaceuticals, etc. It can be suitably used as a gas barrier layer for packaging materials such as films.
In particular, the multilayer structure of the present invention is particularly useful as a packaging material for foods subjected to hot water treatment because of its excellent gas barrier properties after hot water treatment.

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.

[Example 1]
<Manufacture of alkali metal-containing EVOH resin pellets>
EVOH resin [ethylene content 29 mol%, melting point 188 ° C.] (A) water / methanol (water / methanol = 40/60 mixing weight ratio) mixed solution (60 ° C., EVOH resin concentration 45%) maintained at 5 ° C. The extruded water tank was extruded in a strand shape and solidified, and then cut with a cutter to obtain EVOH resin pellets (diameter 4 mm, length 4 mm). Next, the obtained pellets were washed with water, and then poured into an aqueous solution containing 0.1% sodium acetate, stirred at 35 ° C. for about 4 hours, and further 75 ° C. by a batch tower type fluidized bed dryer. EVHR resin pellets of MFR 8.0 g / 10 min (210 ° C., load 2160 g) containing 110 ppm of sodium acetate in terms of sodium, dried for 3 hours at 125 ° C. in a batch-type ventilated box dryer Got.

<Manufacture of multilayer structure>
Using a coextrusion multi-layer film forming apparatus having a 5-type 7-layer type feed block, a multi-layer film forming die and a take-up machine, co-extrusion is carried out under the following conditions, and cooling is performed by a chill roll in which cooling water circulates. Multi-layer structure of layers (cyclic olefin resin / acid-modified olefin elastomer / EVOH resin / acid-modified olefin elastomer / cyclic olefin resin / adhesive resin / polypropylene, thickness (μm): 10/5/10/5 / 10/20/40).
(Material conditions)
-As an EVOH resin, ethylene-containing unit content of 29 mol% obtained above, saponification degree 99.7 mol%, MFR 8.0 g / 10 min (210 ° C, load 2160 g), Na content 110 ppm A saponified vinyl acetate copolymer was used.
As the cyclic olefin resin, an ethylene cyclic olefin copolymer (“TOPAS 7010F-600” manufactured by Polyplastics Co., Ltd.) having a Tg of 110 ° C. was used.
-As the acid-modified olefin elastomer (adhesive resin) through the EVOH layer / cyclic olefin resin layer, an olefin thermoplastic elastomer ("ZELAS MC721APR5" manufactured by Mitsubishi Chemical Corporation) was used.
-Polypropylene ("EA7AD" manufactured by Nippon Polypro Co., Ltd.) was used as the sealant layer.
-Adhesive polyolefin ("Admer QF551" manufactured by Mitsui Chemicals, Inc.) was used as an adhesive resin through the cyclic olefin resin layer / sealant layer.
(Extrusion conditions)
・ Cyclic olefin resin layer: 40mmφ single screw extruder (barrel temperature: 220 ° C)
EVOH resin layer: 40 mmφ single screw extruder (barrel temperature: 230 ° C.)
-Acid-modified olefin elastomer layer: 32mmφ single screw extruder (barrel temperature: 220 ° C)
・ Adhesive resin layer: 50mmφ single screw extruder (barrel temperature: 220 ° C)
-Sealant layer: 40mmφ single screw extruder (barrel temperature: 220 ° C)
・ Die: 5 types, 7 layers type feed block die
・ Cooling roll temperature: 50 ° C

<Retort processing>
The multilayer structure obtained above was subjected to retort treatment at 123 ° C. for 33 minutes using a high-temperature and high-pressure cooking sterilizer (“Flavor Ace RCS-40RTGN” manufactured by Nisaka Seisakusho).

<Evaluation of multilayer structure>
About the multilayer structure obtained above, the multilayer structure before and after the retort treatment was used as a test piece, and a tabletop precision universal testing machine (manufactured by Shimadzu Corporation, “AGS-H”) was used as described in ASTM F1306-90. Based on the method, the test force at break was evaluated as follows.

(1) Breaking point test force A 3.2 mm diameter hemispherical probe is pierced from a cyclic olefin resin layer side at a speed of 50 ± 5 mm per minute with respect to a 35 mm diameter circular test piece, and the needle penetrates. The maximum test force was measured and used as the test force at break.

[Comparative Example 1]
In Example 1, the obtained pellets were washed with water and then poured into an aqueous solution containing 0.1% sodium acetate, and instead of stirring at 35 ° C. for about 4 hours, 0.5% acetic acid water was used. After washing, EVOH resin pellets were produced in the same manner as in Example 1 except that they were put into water and stirred at 35 ° C. for about 4 hours, and evaluated in the same manner. The obtained EVOH resin pellets contained 1 ppm of sodium acetate in terms of sodium, and MFR 9.0 g / 10 min (210 ° C., load 2160 g).

  The evaluation results of Examples and Comparative Examples are summarized in Table 1.

[Table 1]

  As can be seen from Table 1, by using a cyclic olefin resin having a specific glass transition point and using an EVOH resin containing a specific amount of alkali metal, the breaking point test force before and after the retort treatment It was possible to obtain a multi-layered structure excellent in that is, that is, excellent in puncture resistance during retort processing.

  Since the multilayer structure of the present invention is excellent in puncture resistance during retort processing, it is suitable for packaging materials for articles to be subjected to retort processing.

Claims (2)

A cyclic olefin resin layer (γ) having a glass transition point of 85 ° C. to 130 ° C. is formed on at least one surface of the saponified ethylene-vinyl ester copolymer layer (α) via an acid-modified olefin elastomer layer (β). ) In which the ethylene-vinyl ester copolymer saponified product contains 5 to 1000 ppm of alkali metal. The multilayer structure according to claim 1 manufactured by coextrusion.