JP4869120B2 - Multilayer stretched film - Google Patents

Description

  The present invention relates to a multilayer stretched film having a layer containing an ethylene-vinyl alcohol copolymer and a water-swellable layered inorganic compound.

  Ethylene-vinyl alcohol copolymer (hereinafter abbreviated as EVOH) is excellent in gas barrier properties, fragrance retention, transparency, solvent resistance, oil resistance, and oxygen in foods, pharmaceuticals, industrial chemicals, agricultural chemicals, etc. It is widely used as a packaging material for articles that should be prevented from oxidative deterioration due to aging. For the purpose of further improving the gas barrier property, a resin composition in which a water-swellable layered inorganic compound is finely dispersed in EVOH, and a film, a sheet and the like using the same are proposed. (For example, refer to Patent Document 1.)

  On the other hand, the characteristics of EVOH vary greatly depending on moisture and humidity. For example, gas barrier properties and strength are greatly reduced in a high humidity environment. Therefore, when used as a packaging material, EVOH is resistant to moisture such as polyester resin and polyolefin resin. In many cases, it is used as a multilayer structure in which a thermoplastic resin with excellent properties is laminated on the outside of the EVOH layer. In this case, the strength and the gas barrier property of the EVOH layer are improved by improving the orientation and crystallization of the thermoplastic resin layer. For this purpose, a stretching process is generally performed. (For example, see Patent Document 2.)

However, EVOH containing a water-swellable layered inorganic compound is prone to whitening due to interfacial peeling between the resin and the inorganic compound during stretching, and as a result, the transparency of the obtained stretched film is impaired, and is valuable as a packaging material. It had the subject that it falls.
JP 2004-315793 A Japanese Patent Publication No. 07-0664019

  An object of the present invention is to provide an EVOH / water-swellable layered inorganic compound layer-containing multilayer stretched film having excellent gas barrier properties and further improved transparency.

（ここで、Ｒ¹は水素または有機基を表わし、Ｘはエーテル結合を除く結合鎖を表わし、ｎは０または１を表し、Ｒ²〜Ｒ⁴はそれぞれ水素または有機基を表わす） As a result of intensive studies in view of the above circumstances, the present inventor used EVOH (A) having the following structural unit (1) as EVOH, and a multilayer having a layer containing this and a water-swellable layered inorganic compound (B) The inventors have found that the object of the present invention can be achieved by a multilayer stretched film obtained by stretching a film, thereby completing the present invention.

(Wherein R ¹ represents hydrogen or an organic group, X represents a bond chain excluding an ether bond, n represents 0 or 1, and R ^{2 to} R ⁴ each represent hydrogen or an organic group)

  In the present invention, when EVOH has such a structural unit, the affinity with the water-swellable layered inorganic compound is improved, or the flexibility of EVOH is improved so that the water-swellable layered inorganic compound during stretching is improved. It is presumed that interfacial peeling is suppressed, and as a result, a multi-layer stretched film excellent in transparency without whitening due to stretching is obtained.

  Since the multilayer stretched film of the present invention is excellent in gas barrier properties and transparency, it is extremely suitable as a packaging material for foods and pharmaceuticals.

Hereinafter, the present invention will be specifically described.
In addition, description of the component requirements described below is an example (representative example) of the embodiment of this invention, and is not specified by these content.

First, EVOH (A) used in the present invention will be described.
In the present invention, EVOH, that is, an ethylene-vinyl alcohol copolymer means one obtained by saponifying a copolymer of ethylene and a vinyl ester monomer.
EVOH (A) used in the present invention is EVOH containing the following structural unit (1), wherein R ^{1 in the} structural unit (1) represents hydrogen or an organic group, X represents a bonding chain, and n represents 0. Or 1 is represented and R < ² > -R < ⁴ > represents hydrogen or an organic group, respectively.

In the structural unit (1) in the EVOH (A), the main chain substituent R ¹ and the side chain substituents R ^{2 to} R ⁴ are all hydrogen atoms, and the bonding chain (X) It is desirable that _n of n is 0, that is, a single bond, and the hydrogen atom may be substituted with an organic group as long as its amount and size do not significantly impair the resin properties.
Such EVOH (A) contains 0.1 to 30 mol% of structural unit (1) and 10 to 60 mol% of structural units derived from ethylene, and 90 mol% or more of the remaining portion is vinyl alcohol structural units. Some are preferably used.

In addition, when _n of the bond chain (X) _n of the structural unit (1) is 1, any bond chain other than an ether bond can be applied, and is not particularly limited, but other than alkylene, alkenylene, alkynylene, phenylene, hydrocarbons (these hydrocarbons fluorine, chlorine, may be substituted with halogen such as bromine and the like) of the naphthylene other, -CO -, - COCO -, - CO (CH 2) m CO- , —CO (C ₆ H ₄ ) CO—, —S—, —CS—, —SO—, —SO ₂ —, —NR—, —CONR—, —NRCO—, —CSNR—, —NRCS—, — _{NRNR -, - HPO 4 -,} - Si (OR) 2 -, - OSi (OR) 2 -, - OSi (OR) 2 O -, - Ti (OR) 2 -, - OTi (OR) 2 -, - _{OTi (OR) 2 O -,} - Al (OR) -, - OAl (OR) - -OAl (OR) O-, etc. (R is each independently an optional substituent, preferably a hydrogen atom or an alkyl group, and m is a natural number). And alkylene is preferable, and those having 6 or less carbon atoms are preferably used.
In the case where the bond chain X contains an ether bond, the ether bond portion is likely to be thermally decomposed at the time of film production by melt molding, stretching or heat setting, and thermal stability may be insufficient.

In addition, when R ¹ and R ^{2 to} R ^{4 of} the structural unit (1) are organic groups, the organic group is not particularly limited, but for example, a methyl group, ethyl group, n-propyl group, isopropyl group, n- C1-C4 alkyl groups, such as a butyl group, an isobutyl group, a tert-butyl group, are preferable, and it has substituents, such as a halogen group, a hydroxyl group, an ester group, a carboxylic acid group, and a sulfonic acid group, as needed. It may be.

The production method of EVOH (A) used in the present invention is not particularly limited, but the EVOH containing the structural unit (1) in which the bond chain which is the most preferable structure is a single bond ( _n in (X) n is 0) is used. Taking (A) as an example, 3,4-diol-1-butene, 3,4-diacyloxy-1-butene, 3-acyloxy-4-ol-1-butene, 4-acyloxy-3-ol- as comonomers 1-butene, 3,4-diacyloxy-2-methyl-1-butene, 2,2-dialkyl-4-vinyl-1,3-dioxolane, copolymerized with vinyl ester monomers and ethylene Examples thereof include a method of saponifying the obtained copolymer, or a method of saponifying and decarboxylating the obtained copolymer using vinyl ethylene carbonate as a comonomer.

  Among these, 3,4-diacyloxy-1-butene is preferable in that it has excellent copolymerization reactivity with a vinyl ester monomer and ethylene, and there are few problems of lowering the degree of polymerization. Further, a by-product resulting from a saponification reaction is a vinyl ester. It is preferable to use 3,4-diacetoxy-1-butene which is common to vinyl acetate which is frequently used as a monomer. Further, the monomer may contain 3,4-diacetoxy-1-butane, 1,4-diacetoxy-1-butene, 1,4-diacetoxy-1-butane or the like as a small amount of impurities.

  In addition, examples in which the bonding chain X is alkylene include 4,5-diol-1-pentene, 4,5-diacyloxy-1-pentene, 4,5-diol-3-methyl-1-pentene, 4,5- Copolymers obtained by copolymerizing diol-3-methyl-1-pentene, 5,6-diol-1-hexene, 5,6-diacyloxy-1-hexene, etc. with vinyl ester monomers and ethylene The method of making it.

  Vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, versatic. Although vinyl acid acid etc. are mentioned, vinyl acetate is preferably used especially from an economical viewpoint.

  Hereinafter, the copolymerization method using 3,4-diacetoxy-1-butene as a comonomer will be described in detail, but the present invention is not limited thereto.

  There are no particular limitations on the copolymerization of 3,4-diacyloxy-1-butene with vinyl ester monomers and ethylene monomers, and known methods such as bulk polymerization, solution polymerization, suspension polymerization, dispersion polymerization, or emulsion polymerization are known. Although a method can be adopted, solution polymerization is usually performed.

The method for charging the monomer component at the time of copolymerization is not particularly limited, and any method such as batch charging, split charging, continuous charging, etc. may be employed.
The copolymerization ratio of 3,4-diasiloxy-1-butene and the like is not particularly limited, but the copolymerization ratio may be determined in accordance with the amount of the structural unit (1) introduced.
Further, the ethylene content in the copolymer can be controlled by the ethylene pressure during the polymerization, and it cannot be generally determined by the intended ethylene content, but is usually in the range of 25 to 80 kg / cm ² . Selected from.

Examples of the solvent used for such copolymerization include lower alcohols such as methanol, ethanol, propanol and butanol, and ketones such as acetone and methyl ethyl ketone. Methanol is preferably used industrially.
The amount of the solvent used may be appropriately selected in consideration of the chain transfer constant of the solvent in accordance with the degree of polymerization of the target copolymer. For example, when the solvent is methanol, S (solvent) / M ( Monomer) = 0.01 to 10 (weight ratio), preferably 0.05 to 7 (weight ratio).

  In the copolymerization, a polymerization catalyst is used. Examples of the polymerization catalyst include known radical polymerization catalysts such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, lauryl peroxide, and t-butylperoxyneodecano. Ate, t-butylperoxypivalate, α, α′bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecano Peroxyesters such as 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-hexylperoxypivalate, di-n-propylperoxydicarbonate , Di-iso-propyl peroxydicarbonate], di-sec-butyl Ruperoxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethylperoxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, dimethoxybutylperoxydicarbonate, di ( Peroxydicarbonates such as 3-methyl-3-methoxybutylperoxy) dicarbonate, diacyl peroxides such as di (3,3,5-trimethylhexanoyl) peroxide, diisobutyryl peroxide, dilauroyl peroxide And low temperature active radical polymerization catalysts.

The amount of the polymerization catalyst used varies depending on the type of catalyst and cannot be determined unconditionally, but is arbitrarily selected according to the polymerization rate. For example, when azobisisobutyronitrile or acetyl peroxide is used, it is usually 10 to 2000 ppm, and particularly preferably 50 to 1000 ppm relative to the vinyl ester monomer.
Moreover, the reaction temperature of a copolymerization reaction is normally selected from the range of about 40 degreeC-a boiling point by the solvent and pressure to be used.

  In the present invention, an ethylenically unsaturated monomer that can be copolymerized may be copolymerized as long as the effects of the present invention are not impaired during the above copolymerization. Examples of such monomers include propylene, 1- Olefins such as butene and isobutene, hydroxy group-containing α-olefins such as 3-buten-1-ol and 4-penten-1-ol and derivatives thereof, acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid , (Anhydrous) maleic acid, unsaturated acid such as (anhydride) itaconic acid or salts thereof, mono- or dialkyl esters having 1 to 18 carbon atoms, acrylamide, N-alkyl acrylamide having 1 to 18 carbon atoms, N, N- Dimethylacrylamide, 2-acrylamidopropanesulfonic acid or its salt, acrylamidopropyldimethylamine or its acid salt Or acrylamides such as quaternary salts thereof, methacrylamide, N-alkylmethacrylamide having 1 to 18 carbon atoms, N, N-dimethylmethacrylamide, 2-methacrylamidepropanesulfonic acid or a salt thereof, methacrylamidepropyldimethylamine Or methacrylamide such as acid salt or quaternary salt thereof, N-vinylamide such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, vinyl cyanide such as acrylonitrile, methacrylonitrile, carbon number 1-18 alkyl ethers such as alkyl vinyl ethers, hydroxyalkyl vinyl ethers, alkoxyalkyl vinyl ethers, vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl bromide, vinyl Orchids, allyl acetate, allyl chloride, allyl alcohol, dimethylallyl alcohol, trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride, acrylamide-2-methylpropanesulfonic acid, glycerin monoallyl ether, ethylene carbonate, etc. Can be mentioned.

  Furthermore, N-acrylamidomethyltrimethylammonium chloride, N-acrylamidoethyltrimethylammonium chloride, N-acrylamidopropyltrimethylammonium chloride, 2-acryloxyethyltrimethylammonium chloride, 2-methacryloxyethyltrimethylammonium chloride, 2-hydroxy-3- Cationic group-containing monomers such as methacryloyloxypropyltrimethylammonium chloride, allyltrimethylammonium chloride, methallyltrimethylammonium chloride, 3-butenetrimethylammonium chloride, dimethyldiallylammonium chloride, diethyldiallylammonium chloride, acetoacetyl group-containing monomers And so on.

  Further, the above-mentioned vinyl silanes include vinyl trimethoxy silane, vinyl methyl dimethoxy silane, vinyl dimethyl methoxy silane, vinyl triethoxy silane, vinyl methyl diethoxy silane, vinyl dimethyl ethoxy silane, vinyl isobutyl dimethoxy silane, vinyl ethyl dimethoxy silane, vinyl methoxy. Dibutoxysilane, vinyldimethoxybutoxysilane, vinyltributoxysilane, vinylmethoxydihexyloxysilane, vinyldimethoxyhexyloxysilane, vinyltrihexyloxysilane, vinylmethoxydioctyloxysilane, vinyldimethoxyoctyloxysilane, vinyltrioctyloxy Silane, vinylmethoxydilauryloxysilane, vinyldimethoxylauryloxysilane, vinylmethoxydioleoxy Emissions, and vinyl dimethoxy I acetoxyphenyl silane.

  In addition, it is preferable in terms of suppressing coloring of EVOH (A) obtained by allowing a hydroxylactone compound or a hydroxycarboxylic acid to coexist with the above catalyst at the time of polymerization. The hydroxylactone compound includes a lactone ring and a hydroxyl group in the molecule. It is not particularly limited as long as it has a compound, and examples thereof include L-ascorbic acid, erythorbic acid, glucono delta lactone, etc., preferably L-ascorbic acid and erythorbic acid are used, and hydroxycarboxylic acid Examples thereof include glycolic acid, lactic acid, glyceric acid, malic acid, tartaric acid, citric acid, salicylic acid and the like, and citric acid is preferably used.

  The amount of the hydroxylactone compound or hydroxycarboxylic acid used is usually 0.0001 to 0.1 parts by weight, more preferably 0.0005 to 0.05 parts by weight, and particularly 0 to 100 parts by weight of vinyl acetate. 0.001 to 0.03 part by weight is preferable. If the amount used is too small, these effects may not be obtained. On the other hand, if the amount used is too large, polymerization of vinyl acetate is inhibited, which is not preferable.

  There is no particular limitation on charging such a compound into the polymerization system, but it is usually charged into a polymerization reaction system by diluting with a solvent such as an aliphatic ester containing lower aliphatic alcohol or vinyl acetate, water, or a mixed solvent thereof. .

  The obtained copolymer is then saponified. In such saponification, an alkali catalyst or an acid catalyst is used in a state where the copolymer obtained above is dissolved in an alcohol or a hydrous alcohol. Is called. Examples of the alcohol include methanol, ethanol, propanol, tert-butanol and the like, and methanol is particularly preferably used. The concentration of the copolymer in the alcohol is appropriately selected depending on the viscosity of the system, but is usually selected from the range of 10 to 60% by weight.

Catalysts used for saponification include alkali catalysts such as hydroxides and alcoholates of alkali metals such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, potassium methylate, lithium methylate, alcoholates, sulfuric acid, hydrochloric acid Acid catalysts such as nitric acid, metasulfonic acid, zeolite, and cation exchange resin.
The amount of the saponification catalyst used is appropriately selected depending on the saponification method, the target degree of saponification, and the like. Usually, when an alkali catalyst is used, a vinyl ester monomer and 3,4-diacyloxy-1- 0.001-0.1 equivalent with respect to the total amount of monomers, such as butene, Preferably 0.005-0.05 equivalent is suitable.

With regard to such a saponification method, batch saponification, continuous saponification on a belt, and continuous saponification of a tower type are possible depending on the target saponification degree, etc., and the amount of alkali catalyst during saponification can be reduced and saponification reaction is high. For reasons such as efficiency and ease of progress, tower saponification under constant pressure is preferably used. The pressure during saponification cannot be generally specified depending on the target ethylene content, but is selected from the range of ^{2 to} 7 kg / cm ² , and the temperature at this time is 80 to 150 ° C., preferably from 100 to 130 ° C. Selected.

  Thus, the ethylene content and the saponification degree of EVOH (A) to be obtained are not particularly limited, but the ethylene content is 10 to 60 mol%, more preferably 20 to 50 mol%, particularly 25 to 48 mol%, The degree of conversion is preferably 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 99 mol% or more, and if the ethylene content is too low, the gas barrier property under high humidity conditions decreases, The appearance tends to deteriorate, and on the contrary, if it is too much, the gas barrier property tends to decrease, which is not preferable. On the other hand, if the degree of saponification is too low, gas barrier properties and moisture resistance tend to decrease, which is not preferable.

Further, the content of the structural unit (1) introduced into EVOH (A) by copolymerization is not particularly limited, but is 0.1 to 30 mol%, more preferably 0.5 to 20 mol%, In particular, the content is preferably 1 to 10 mol%. If the content is too small, the effect of the present invention is not sufficiently exhibited. On the other hand, if the content is too large, the gas barrier property under high humidity tends to decrease. Absent.
Further, in adjusting the content, it is possible to adjust by blending two or more types of EVOH (A) having different contents of the structural unit (1), and at least one of them is the structural unit (1 EVOH may not be contained.
Regarding EVOH (A) obtained by such blending, the content of the structural unit (1) may be calculated by weight average, and the ethylene content may be determined by weight average. The content of ethylene and the content of structural unit (1) can be calculated from ¹ H-NMR measurement results.

  Further, acids such as acetic acid and phosphoric acid, boric acid or alkali metals, alkaline earth metal salts thereof, various organic acids or metal salts of inorganic acids are added to EVOH (A) within a range not impairing the object of the present invention. This is preferable in terms of improving the thermal stability during melt molding.

  The amount of acetic acid added is usually 0.001 to 1 part by weight with respect to 100 parts by weight of EVOH (A), more preferably 0.005 to 0.2 parts by weight, and particularly 0.010 to 0.1 parts by weight. If the amount added is too small, the content effect may not be sufficiently obtained. On the other hand, if the amount added is too large, it is difficult to obtain a uniform film.

  Moreover, the addition amount of a boron compound is 0.001-1 weight part normally in conversion of boron with respect to 100 weight part of EVOH (A), Furthermore, 0.002-0.2 weight part, Especially 0.005- The content is preferably 0.1 parts by weight. If the amount added is too small, the content effect may not be sufficiently obtained. On the other hand, if the amount added is too large, it is difficult to obtain a uniform film.

  In addition, as metal salts of organic acids or inorganic acids, sodium, potassium, calcium, magnesium, and other organic acids such as acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, behenic acid, sulfuric acid, sulfurous acid, Examples include metal salts of inorganic acids such as carbonic acid and phosphoric acid, and preferred are acetates, phosphates and hydrogen phosphates. The addition amount of the metal salt is usually 0.0005 to 0.1 parts by weight, more preferably 0.001 to 0.05 parts by weight, and particularly preferably 0.000 to 0.05 parts by weight in terms of metal with respect to 100 parts by weight of EVOH (A). The content is preferably 002 to 0.03 parts by weight. If the amount added is too small, the content effect may not be sufficiently obtained. On the other hand, if the amount is too large, it is difficult to obtain a uniform film. In addition, when adding 2 or more types of alkali metal and / or alkaline-earth metal salt to EVOH (A), it is preferable that the sum total is in the range of said addition amount.

  The method for adding acids and their metal salts to EVOH (A) is not particularly limited. A) A porous precipitate of EVOH (A) having a water content of 20 to 80% by weight is mixed with an aqueous solution of acids and its metal salts. A method of drying after contact with an acid or its metal salt, and b) A uniform solution (water / alcohol solution, etc.) of EVOH (A) containing an acid or its metal salt and then in the coagulation liquid Extruding into strands, then cutting the resulting strands into pellets and further drying treatment c) Mixing EVOH (A) with acids and their metal salts at once, and then melt-kneading them with an extruder D) In the production of EVOH (A), the alkali (sodium hydroxide, potassium hydroxide, etc.) used in the saponification step is neutralized with acids such as acetic acid, and the remaining acids such as acetic acid Produced sodium acetate Um, the amounts of alkali metal salts such as potassium acetate may be a method like or to adjust the water washing treatment.

  In addition, EVOH (A) or a composition thereof may contain some monomer residue or saponified monomer, specifically 3,4-diacetoxy-1-butene, as long as the object of the present invention is not impaired. , 4-diol-1-butene, 3,4-diacetoxy-1-butene, 3-acetoxy-4-ol-1-butene, 4-acetoxy-3-ol-1-butene, and the like. .

In addition, EVOH (A) used in the present invention is a blend of EVOH (A) containing structural unit (1) and another EVOH different from this, which also indicates good stretchability and strength after stretching. Such other EVOHs include those having different structural units, those having different ethylene contents, those having different degrees of saponification, and those having different molecular weights.
Examples of the EVOH having a structural unit different from the EVOH having the structural unit (1) include, for example, an EVOH composed only of an ethylene structural unit and a vinyl alcohol structural unit, and a modified EVOH having a functional group such as a 2-hydroxyethoxy group in the side chain of the EVOH. Can be mentioned.

  In addition, when different ethylene contents are used, the structural units may be the same or different, but the ethylene content difference is 1 mol% or more, further 2 mol% or more, particularly 2 to 2 mol%. It is preferably 20 mol%. If the ethylene content difference is too large, the stretchability may be poor, which is not preferable. Moreover, the manufacturing method of 2 or more types of different EVOH (blend product) is not particularly limited, for example, a method of mixing each paste of EVA before saponification and then saponifying, alcohol of each EVOH after saponification or water and alcohol And a method of mixing each solution of EVOH in the form of pellets or powder, and then melt-kneading.

  The EVOH (A) thus obtained or the melt flow rate (MFR) (210 ° C., load 2160 g) of the composition is not particularly limited, but is usually 0.1 to 100 g / 10 minutes, 50 g / 10 min, particularly 2 to 35 g / 10 min is preferable. When the melt flow rate is smaller than the above range, the inside of the extruder is in a high torque state at the time of melt molding, and extrusion processing is difficult. When the MFR is too large, the appearance is deteriorated and the gas barrier property tends to be lowered, which is not preferable.

Next, the water-swellable layered inorganic compound (B) used in the present invention will be described.
The water-swellable layered inorganic compound (B) used in the present invention is not particularly limited, and clay such as smectites such as montmorillonite, beidellite, nontronite, saponite, hectorite, soconite, stevensite, and vermiculite. Examples include minerals, water-swelling fluoromica-based minerals such as Na-type fluorotetrasilicon mica, Na-type teniolite, Li-type teniolite, Na-type hectorite, synthetic mica, etc. Among them, montmorillonite having excellent water swellability is preferably used It is done.

The water-swellable layered inorganic compound (B) can be evaluated for its water swellability by the Japan Bentonite Industry Association standard test method (volume method), and this value is 30 ml / 2 g or more, particularly 40 ml / 2 g or more. It is preferably used, and if the swelling property is too small, the gas barrier property becomes insufficient, which is not preferable.
The water-swellable layered inorganic compound (B) preferably has a large aspect ratio, preferably 50 or more, more preferably 100 or more, and particularly preferably 200 or more. The thing of 20-2000 nm is used.
Further, the water-swellable layered inorganic compound (B) may be subjected to an organic treatment, and as a method of the organic treatment, a compound having an onium ion group such as a quaternary ammonium salt is water-swollen. And a method of mixing with the inorganic layered inorganic compound (B).

  The content of the water-swellable layered inorganic compound (B) in the layer containing EVOH (A) and the water-swellable layered inorganic compound (B) in the multilayer stretched film of the present invention is not particularly limited, but is 100 parts by weight of EVOH. (B) is preferably 0.5 to 100 parts by weight, more preferably 1 to 15 parts by weight, and particularly preferably 2 to 8 parts by weight, and multilayer stretching obtained when the content of (B) is too small. In some cases, the gas barrier property of the film may be insufficient. On the contrary, if the amount is too large, the transparency of the multilayer stretched film may be lowered, and stretching at a high magnification may be difficult, which is not preferable.

Next, the manufacturing method of the multilayer stretched film of this invention is demonstrated.
The layer containing EVOH (A) and the water-swellable layered inorganic compound (B) in the multilayer stretched film of the present invention is usually prepared by previously mixing EVOH (A) and the water-swellable layered inorganic compound (B), After forming a resin composition (hereinafter sometimes abbreviated as EVOH resin composition), it is molded into a multilayer film.

  The method of blending EVOH (A) and the water-swellable layered inorganic compound (B) for obtaining such an EVOH resin composition is not particularly limited, but a melt-mixing method is preferred in that uniform mixing is possible, Furthermore, the method of melt-mixing EVOH (A) having a water content of 20 to 70% by weight and the water-swellable layered inorganic compound (B) favorably disperses the water-swellable layered inorganic compound (B), and water. The swellable layered inorganic compound (B) is preferred because it is present in EVOH (A) in a state where the swelling state is maintained and the layers are spread.

The water content of EVOH in the present invention is measured and calculated by the following method.
[Method of measuring moisture content]
EVOH is weighed (W ₁ ) with an electronic balance, dried in a hot air dryer at 150 ° C. for 5 hours, weighed after being allowed to cool for 30 minutes in a desiccator (W ₂ ), and calculated from the following formula.
Moisture content (%) = [(W ₁ −W ₂ ) / W ₁ ] × 100

Although it does not restrict | limit especially as a method of containing 20 to 70 weight% of water in EVOH (A), It is preferable to contain water uniformly in EVOH (A), and as this method, EVOH (A) A method in which the solution is precipitated in water and washed thoroughly with water to remove the solvent and contain water, a method in which EVOH (A) is treated in pressurized hot water for about 1 to 3 hours, and ethylene- during the production of EVOH (A) Examples thereof include a method in which a paste after saponification of a vinyl acetate copolymer is precipitated in water to contain water.
Of these, the method of precipitating the paste after saponification of the ethylene-vinyl acetate copolymer in water during EVOH (A) production is particularly preferred.
It should be noted that the effect of the present invention cannot be exerted by simply mixing EVOH and water because water is not uniformly contained in EVOH.

  As the method of melt mixing, for example, a known kneading apparatus such as a kneader rudder, an extruder, a mixing roll, a Banbury mixer, a plast mill, etc. can be used. Usually, a single or twin screw extruder is used. It is industrially preferable to use it, and it is also preferable to provide a vent suction device, a gear pump device, a screen device, etc. as needed.

  The EVOH (A) and the water-swellable layered inorganic compound (B) are not particularly limited in the melt mixing, and the EVOH (A) having a water content of 20 to 70% by weight, the water-swellable layered inorganic compound (powder) B) is charged all at once into the hopper of the extruder, or only EVOH (A) having a water content of 20 to 70% by weight is supplied to the hopper, and the powdered water-swellable layered inorganic compound (B) is added to the cylinder of the extruder. You may add from the middle of (for example, a vent hole). Further, water may be added to the water-swellable layered inorganic compound (B) and supplied to the extruder as a slurry or solution using a pump or the like.

  The EVOH and the water-swellable layered inorganic compound (B) used in the present invention may be melt-mixed together, but a part of EVOH and the water-swellable layered inorganic compound (B) are previously melt-mixed to obtain It is also a preferred embodiment to melt mix the resulting masterbatch with the remaining EVOH. In that case, the EVOH used for the master batch and the remaining EVOH may be the same or different.

The EVOH resin composition thus obtained is dried before being formed into a multilayer film, if necessary.
As such a drying method, various drying methods can be employed. For example, fluidized drying performed while the pelletized EVOH resin composition is mechanically or stirred and dispersed by hot air, and stationary drying performed without being subjected to dynamic actions such as stirring and dispersion. Examples of the dryer for performing fluidized drying include a cylindrical / grooved stirring dryer, a circular tube dryer, a rotary dryer, a fluidized bed dryer, a vibrating fluidized bed dryer, a conical rotary dryer, and the like. In addition, as a dryer for performing stationary drying, a batch box dryer can be used as a material stationary type, and a band dryer, a tunnel dryer, a vertical dryer, etc. can be used as a material transfer type. However, it is not limited to these. It is also possible to combine fluidized drying and stationary drying.

Air or an inert gas (nitrogen gas, helium gas, argon gas, etc.) is used as the heating gas used in the drying process, and the temperature of the heating gas is 40 to 150 ° C., which is the productivity and the heat of EVOH. It is preferable in terms of preventing deterioration. Further, drying in a reduced pressure state is preferable from the viewpoint of preventing thermal deterioration because it can be dried at a lower temperature or in a shorter time. The time for the drying treatment depends on the water content of the object and its treatment amount, but is usually preferably about 15 minutes to 200 hours from the viewpoint of productivity and prevention of thermal deterioration.
Another drying method includes a method of removing moisture from a vent or the like when the EVOH (A) and the water-swellable layered inorganic compound (B) are melt-mixed with an extruder.
The water content after the drying treatment is usually 0.001 to 5% by weight, more preferably 0.01 to 2% by weight, and particularly preferably 0.1 to 1 part by weight. If it is less than 0.001% by weight, long-run moldability tends to be reduced. Conversely, if it exceeds 5% by weight, foaming may occur during extrusion molding.

  The EVOH resin composition thus obtained can be processed into a film as it is, but in the present invention, various additives can be blended in such a resin composition as long as the object of the present invention is not impaired. Such additives include saturated aliphatic amides (such as stearic acid amide), unsaturated fatty acid amides (such as oleic acid amide), bis fatty acid amides (such as ethylene bisstearic acid amide), fatty acid metal salts (such as calcium stearate, Such as magnesium stearate), 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), lubricant, inorganic salt (for example, hydrotalcite), plasticizer (for example, ethylene glycol, Aliphatic polyhydric alcohols such as glycerin and hexanediol), heat stabilizers, light stabilizers, antioxidants, ultraviolet absorbers, colorants, antistatic agents, surfactants, antibacterial agents, antiblocking agents, slip agents , Fillers (eg inorganic fillers), oxygen absorbers, other resins ( In example polyolefins, polyamides, etc.) and the like.

  Next, the EVOH resin composition containing EVOH (A) and the water-swellable layered inorganic compound (B) is laminated with another substrate to form a multilayer film. As a lamination method when laminating with another base material, for example, a method of melt extrusion laminating another base material on the film, sheet or the like of the EVOH resin composition of the present invention, and conversely melting the resin on the other base material A method of extrusion laminating, a method of co-extrusion of the resin and another substrate, an organic titanium compound, an isocyanate compound, a polyester compound, a polyurethane compound and the like of the resin (layer) and another substrate (layer) are known. Include a method of dry laminating using the above adhesive, a method of removing the solvent after coating the solution of the resin on another substrate, and coextrusion in terms of good stretchability as a laminate. Is preferred.

  As the co-extrusion method, specifically, a known method such as a multi-many hold die method, a feed block method, a multi-slot die method, or a die external bonding method can be employed. As the shape of the die, a T die, a round die or the like can be used, and the melt molding temperature at the time of melt extrusion is preferably 150 to 300 ° C.

  As such other base materials, thermoplastic resins are useful. Specifically, linear low density polyethylene, low density polyethylene, ultra-low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer , Ionomer, ethylene-propylene (block and random) copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) Polyolefin resins and polyesters in a broad sense, such as copolymers, polybutenes, polypentenes or other olefins or copolymers, or those olefins alone or copolymers grafted with unsaturated carboxylic acids or esters thereof Resin, polyamide resin (including copolyamide) ), Polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene, vinyl ester resins, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, aromatic or aliphatic polyketones, and further reducing them Polyalcohols, and other EVOHs may be mentioned. From the viewpoint of practicality such as physical properties (particularly strength) of the laminate, polyolefin-based thermoplastic resins and polyamide-based resins are preferable, and in particular, polyethylene, polypropylene, ethylene -A propylene (block or random) copolymer and an ethylene-vinyl acetate copolymer are preferably used.

  Further, when the multilayer film is extrusion-coated with another base material, or when a film or sheet of another base material is laminated using an adhesive, the base material is not limited to the thermoplastic resin described above. Materials (paper, metal foil, uniaxial or biaxially stretched plastic film or sheet and inorganic compound deposits thereof, woven fabric, non-woven fabric, metallic cotton, wood, etc.) can be used.

  The layer structure of the multilayer film is such that the EVOH resin composition-containing layer is a (a1, a2,...), And the thermoplastic resin-containing layer is b (b1, b2,...). If there is not only a two-layer structure of a / b, but also b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / Any combination such as b1 / a / b1 / a / b1 / b2 is possible. Furthermore, when R is a regrind layer comprising at least a mixture of the EVOH resin composition and a thermoplastic resin, b / R / a, b / R / a / b, b / R / a / R / b, b / a / R / a / b, b / R / a / R / a / R / b, etc. is there. In the above layer structure, an adhesive resin layer can be provided between the respective layers as necessary, and various adhesive resins can be used, and the stretchability is excellent. It is preferable in that a laminate can be obtained. It varies depending on the type of resin b, but cannot be generally stated. However, an unsaturated carboxylic acid or its anhydride is added to an olefin polymer (the above-mentioned polyolefin resin in the broad sense) or a graft reaction. Examples thereof include modified olefin polymers containing carboxyl groups obtained by chemically bonding such as 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-ethylene Le acrylate copolymer, maleic anhydride graft-modified ethylene anhydride - one or a mixture of two or more species selected from vinyl acetate copolymers and the like as preferred. At this time, the amount of the unsaturated carboxylic acid or anhydride thereof contained in the thermoplastic resin is preferably 0.001 to 3% by weight, more preferably 0.01 to 1% by weight, particularly preferably 0.03. ~ 0.5 wt%. If the amount of modification in the modified product is small, the adhesiveness may be insufficient. On the other hand, if the amount is too large, a crosslinking reaction may occur and the moldability may be deteriorated. These adhesive resins can be blended with EVOH compositions, other EVOH, polyisobutylene, rubber / elastomer components such as ethylene-propylene rubber, and b-layer resins. In particular, blending a polyolefin resin different from the base polyolefin resin of the adhesive resin is useful because the adhesiveness may be improved.

  The base resin layer may contain an antioxidant, an antistatic agent, a lubricant, a core material, an antiblocking agent, an ultraviolet absorber, a wax and the like as conventionally known.

  The multilayer film (laminated body) as described above is then subjected to (heated) stretching treatment, and the (heated) stretching treatment is to chuck a film or sheet-like laminated body that is thermally uniformly heated. , Plug, vacuum force, pneumatic force, blow, etc. means an operation for uniformly forming into a tube or film. Such stretching may be either uniaxial stretching or biaxial stretching. In some cases, simultaneous stretching or sequential stretching may be used.

  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. In the case of biaxial stretching, both a simultaneous biaxial stretching method and a sequential biaxial stretching method can be employed. The stretching temperature is selected from the range of about 40 to 170 ° C, preferably about 60 to 160 ° C. If the stretching temperature is less than 40 ° C, the stretchability becomes poor, and if it exceeds 170 ° C, it is difficult to maintain a stable stretched state.

In addition, it exists in the tendency for a physical property to improve, so that a draw ratio is high, and it is preferable that it is 4 to 80 times, further 9 to 80 times, especially 20 to 80 times by area ratio.
Since the multilayer stretched film of the present invention is excellent in stretchability, it does not cause pinholes, cracks, stretch unevenness, uneven thickness, etc. at the time of stretching, and a multilayer stretched film that has excellent gas barrier properties and does not deteriorate transparency due to bleaching is obtained. It is done.

For the purpose of imparting dimensional stability to the obtained multilayer stretched film, heat stretching may be performed after the stretching is completed. The heat setting can be carried out by a known means, and the heat treatment is performed at 80 to 180 ° C., preferably 100 to 165 ° C. for about 2 to 600 seconds while keeping the stretched film in a tension state.
In addition, when the multilayer stretched film of the present invention is used as a shrink film, in order to impart heat shrinkability, the above heat fixing is not performed, for example, the film after stretching is cooled and fixed by applying cold air, etc. Process.

The thickness of the thermoplastic resin layer and the adhesive resin layer of the multilayer stretched film cannot be generally stated depending on the layer structure, the type of thermoplastic resin, the type of adhesive resin, the use and packaging form, the required physical properties, etc. The thermoplastic resin layer is selected from the range of 1 to 200 μm, more preferably 2 to 50 μm, and the adhesive resin layer is selected from the range of 0.1 to 30 μm, further 0.2 to 10 μm.
The thickness of the EVOH resin composition-containing layer varies depending on the required gas barrier properties, but is usually 0.5 to 30 μm, more preferably 0.8 to 10 μm, and particularly preferably 1 to 5 μm. If it is too thin, sufficient gas barrier properties may not be obtained. Conversely, if it is too thick, the flexibility of the film tends to be insufficient.

  Moreover, the transparency of the multilayer stretched film of the present invention is preferably 10 or less, more preferably 6 or less, and particularly preferably 3 or less as a haze value.

  The multilayer stretched film thus obtained has good gas barrier properties and excellent transparency, and thus is useful as various packaging materials such as foods, pharmaceuticals, industrial chemicals and agricultural chemicals.

Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to the examples.
In the following, “%” and “parts” refer to weight basis unless otherwise specified.

Example 1
(1) EVOH 500 kg Preparation polymerization reactor of vinyl acetate cooling 1 m ³ with a coil (A1), methanol 100 kg, acetyl peroxide 500 ppm (to vinyl acetate), citric acid 20 ppm (to vinyl acetate), and 3,4 -14 kg of diacetoxy-1-butene was charged, the system was replaced with nitrogen gas, and then replaced with ethylene. Further, ethylene was injected until the pressure reached 35 kg / cm ^2, and the temperature was raised to 67 ° C while stirring. Polymerization was started. Further, 4.5 kg of 3,4-diacetoxy-1-butene was added at a rate of 15 g / min, and the polymerization reaction was stopped 6 hours after the polymerization rate reached 50%.
The content of the structural unit (1) in the obtained ethylene-vinyl acetate copolymer was 2.5 mol%, and the ethylene content was 29 mol%. The content of the structural unit (1) is calculated from ¹ H-NMR (internal standard substance: tetramethylsilane, solvent: d6-DMSO, “V-NCE DPX400” manufactured by Nippon Bruker, Inc.).

The methanol solution of the obtained ethylene-vinyl acetate copolymer was supplied at a rate of 10 kg / hour from the top of the plate tower (saponification tower), and at the same time, 0.1% to the acetic acid group in the copolymer. A methanol solution containing 012 equivalents of sodium hydroxide was fed from the top of the tower. On the other hand, methanol was supplied from the bottom of the tower at 15 kg / hour. At that time, the temperature inside the tower was 100 to 110 ° C., and the tower pressure was 3 kg / cm ² G. From 30 minutes after the start of charging, a methanol solution of EVOH (A1) having a 1,2-glycol structural unit (EVOH (A1) 30%, methanol 70%) was taken out.
The EVOH (A1) had a saponification degree of 99.5 mol%.

  Next, a 30% methanol solution of EVOH (A1) was supplied from the top of the methanol / water solution adjusting tower at 10 kg / hour, from the bottom of the tower was 120 ° C. methanol vapor at 4 kg / hour, and steam at 2.5 kg / hour. It was fed at a rate, and 6 equivalents of methyl acetate was fed from the center of the column with respect to the amount of sodium hydroxide used for saponification. At that time, the temperature in the tower was 95 to 110 ° C. Methanol was derived from the top of the column at 8 kg / hour, and a water / alcohol solution of EVOH (A1) (resin concentration 35%) was derived from the bottom of the column.

  The obtained EVOH (A1) water / alcohol solution was extruded from a nozzle with a pore diameter of 4 mm into a coagulating liquid tank maintained at 5 ° C. composed of 5% methanol and 95% water to be solidified. The strands were cut with a cutter to obtain EVOH (A1) porous pellets having a diameter of 3.8 mm, a length of 4 mm, and a moisture content of 45%. Thereafter, after washing with 100 parts of water with respect to 100 parts of the porous pellets, it was put into a mixed solution containing 0.032% boric acid and 0.007% calcium dihydrogen phosphate, at 30 ° C. After stirring for 5 hours, the product was taken out to obtain EVOH (A1) composition pellets having a moisture content of 45%. Further, the porous pellets were dried for 12 hours by passing nitrogen gas having a temperature of 70 ° C. and a moisture content of 0.6% in a batch-type ventilated box dryer to a moisture content of 30%. Drying was performed for 12 hours with nitrogen gas having a temperature of 120 ° C. and a water content of 0.5% using a type tower type fluid dryer, thereby obtaining pellets of an EVOH (A1) composition having a water content of 0.3%. Such pellets contained 0.015 part of boric acid (in terms of boron) and 0.005 part of calcium dihydrogen phosphate (in terms of phosphate group) with respect to 100 parts of EVOH (A1). Further, the MFR of this EVOH (A1) composition was 3.5 g / 10 min (measured at 210 ° C. and 2160 g).

(2) Production of EVOH (A1) resin composition and single layer film EVOH (A1) composition prepared to a moisture content of 45% and natural montmorillonite (B) which is a water-swellable layered inorganic compound (B) (Kunimine Mining Co., Ltd.) “Kunipia F”, cation exchange capacity 109 meq / 100 g, swelling power 62 mL / 2 g, aspect ratio 320, in a twin screw extruder (screw diameter 15 mm, L / D = 60, “KZW15-60MG” manufactured by Technobel) The mixture was melted and mixed under the following conditions. At this time, the EVOH (A) composition having a water content of 45% was supplied from the hopper, and the water-swellable layered inorganic compound (B) was supplied from the biaxial side feeder for KZW15 (installed at the C3 position).
[(A1) / (B) melt mixing conditions]
(A1) Composition (water content 45%) supply amount
1.2kg / hour
(B) Supply amount 0.035kg / hour
Screw configuration Full flight Screw speed 200rpm
Dies Strand die (diameter 3mmφ: 1 hole)
Vent all closed Temperature setting C1 65 ℃ C7 90 ℃
C2 90 ° C C8 90 ° C
C3 90 ° C D 90 ° C
C4 90 ° C
C5 90 ° C
C6 90 ° C

The molten mixture was extruded into a strand form from a strand die provided at the exit of the extruder, and cut using a pelletizer to obtain an EVOH resin composition pellet (water content 40%: diameter 2.5 mm, length 3 mm cylindrical). . Subsequently, the obtained pellet was vacuum-dried in an 80 ° C. atmosphere for 7 days to obtain an EVOH resin composition (a) pellet having a water content of 0.3%.
The resin composition (a) obtained above is supplied to a twin-screw extruder (screw diameter: 15 mm, L / D = 60, Technobel KZW15-60MG) equipped with a T die, and a single layer is formed under the following molding conditions. A film (film thickness 30 μm) was produced.

[EVOH resin composition (a) single layer film molding conditions]
(A) Supply amount 1.7 kg / hour
Screw configuration Full flight Screw speed 200rpm
Die T-die (Coat hanger type, Die width 250mm)
Vent Only C7 part is open, others are closed Temperature setting C1 200 ° C D1 220 ° C
C2 220 ° C D2 220 ° C
C3 220 ° C D3 220 ° C
C4 220 ° C D4 220 ° C
C5 220 ° C D5 220 ° C
C6 220 ° C
C7 220 ° C
C8 220 ° C
Cooling roll temperature 30 ° C
Take-off speed 3m / min
Air gap 25mm

(3) Production of Polypropylene Single Layer Film Next, a polypropylene resin (b) (“NOVATEC PP FL6CK” manufactured by Nippon Polypropylene Co., Ltd.), a single screw extruder (“VS40” manufactured by Tanabe Plastics Co., Ltd.) with a T-die, screw diameter 40 mm, L / D = 28) to produce a single layer film (film thickness 100 μm).
[Resin composition (b) single layer film molding conditions]
Screw configuration Full flight (compression ratio 3.5)
Screw rotation speed 72rpm
Die T-die (Coat hanger type, Die width 450mm)
Temperature setting C1 185 ° C H 220 ° C
C2 200 ° C D 200 ° C
C3 220 ° C
C4 230 ° C
Cooling roll temperature 50 ℃
Take-off speed 2.4 m / min
Air gap 80mm

(4) Production of multilayer film On the polypropylene resin (b) single layer film obtained above, commercially available anchor coating agent [main agent: AD-335, curing agent: CAT-10 (both manufactured by Toyo Morton)] After using the main agent: curing agent: solvent (toluene: methyl ethyl ketone = 1: 1 mixed solvent) = 100: 6: 30 to prepare a mixed solution and coating it with a bar coater (NO. 40) And drying with a hot air circulation dryer (drying temperature: 80 ° C., drying time: 90 seconds). The obtained anchor coat-treated polypropylene resin (b) film and the resin composition (a) single layer film are pressure-bonded for 1 second at a nip roll pressure of 2 kg / cm ² using a laminator apparatus (“Hulder Laminator MRK-650Y” manufactured by MKS). Then, a dry lamination treatment was performed to obtain a multilayer film of (b) layer / anchor coat layer / (a) layer = 100/15/30 (μm). Next, dry lamination treatment was performed on the untreated dry laminate side of the (a) layer under the same conditions as described above. (B) layer / anchor coat layer / (a) layer / anchor coat layer / (b) layer = 100/15 A multilayer film of / 30/15/100 (μm) was produced. Thereafter, the obtained film was dried at 80 ° C. for 5 minutes with a hot air circulating dryer, and further aged at 40 ° C. for 48 hours to obtain a multilayer film.

(5) Production of multilayer stretched film The obtained multilayer film was preheated at 150 ° C. for 1 minute with a tenter type biaxial stretching machine, and then stretched at a stretching temperature of 150 ° C. and a stretching speed of 200 mm / sec. Double biaxial stretching was performed, and heat setting was performed at 150 ° C. for 3 minutes to obtain a multilayer stretched film (total thickness: 11 μm, EVOH resin composition layer thickness: 1.3 μm).

The following evaluation was performed about the obtained multilayer stretched film.
<Transparency evaluation>
For the transparency of the obtained multilayer stretched film, the haze value was measured according to JIS K7105 using a haze meter (“NDH2000” manufactured by Nippon Denshoku Co., Ltd.). The results are shown in Table 1.

Example 2
In Example 1, a multilayer stretched film (total thickness: 8 μm, EVOH resin composition layer thickness: 0.7 μm) was prepared in the same manner except that the stretch ratio was changed to 6 times in length and 6 times in width, and evaluated in the same manner. Went. The results are shown in Table 1.

Example 3
In Example 1, a multilayer stretched film (total thickness 6 μm, EVOH resin composition layer thickness 0.7 μm) was prepared in the same manner except that the stretch ratio was changed to 7 times in length and 7 times in width, and evaluated in the same manner. Went. The results are shown in Table 1.

Comparative Example 1
A multilayer film was prepared in the same manner except that EVOH containing no structural unit (1) (ethylene content 29%, saponification degree 99.8%, MFR 3.0) was used instead of EVOH (A1) of Example 1. (Total thickness of 11 μm, EVOH resin composition layer thickness of 1.3 μm) was prepared and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 2
In Comparative Example 1, a multilayer stretched film (total thickness: 8 μm, EVOH resin composition layer thickness: 0.9 μm) was prepared in the same manner except that the stretch ratio was changed to 6 times in length and 6 times in width, and similarly evaluated. Went. The results are shown in Table 1.

Comparative Example 3
In Comparative Example 1, a multilayer stretched film was prepared in the same manner except that the stretch ratio was changed to 7 times in the vertical direction and 7 times in the lateral direction. However, the film may be broken during stretching to obtain a multilayer stretched film having the target stretch ratio. could not.

[Table 1]

Example 4
(1) Preparation of EVOH resin composition EVOH (A1) composition prepared to 60% water content in Example 1 and natural montmorillonite (B) which is a water-swellable layered inorganic compound (B) (manufactured by Kunimine Mining Co., Ltd. Kunipia F ") is supplied to a twin screw extruder (screw diameter 57 mm, L / D = 44," OTE-57-II "manufactured by Osaka Seiki Co., Ltd.) and melted and mixed under the following conditions. EVOH (A1) / A master batch in which montmorillonite (B) was 4/1 (weight ratio) was produced. At this time, EVOH (A1) having a water content of 60% was supplied from the hopper, and montmorillonite (B) was supplied from the biaxial side feeder (installed at the C5 position).

[Mixing conditions]
(A1) Supply amount 130 kg / hour (52 kg / hour as EVOH component)
(B) Supply amount 13 kg / hour screw configuration Normal kneading type screw
(Kneading discs are placed between C1 and C5 and between C6 and C13)
Screw rotation speed 250rpm
Strand die diameter 3.5mmφ: 8 hole vent C8, only C11 part opened, others closed temperature setting C1 65 ° C C9 95 ° C
C2 90 ° C C10 95 ° C
C3 95 ° C C11 95 ° C
C4 95 ° C C12 95 ° C
C5 95 ° C C13 95 ° C
C6 95 ° C AD 95 ° C
C7 95 ° C D 95 ° C
C8 95 ° C
Motor torque 54 Ampere

  Extruded into a strand form from a strand die provided at the exit of the extruder, and cut using a pelletizer to obtain a water-containing pellet (water content 46%: diameter 2.5 mm, length 3 mm cylindrical) of a master batch (A1 + B). . The water-containing pellets were dried for 16 hours by passing nitrogen gas having a temperature of 80 ° C. and a water content of 0.6% in a fluid dryer to a water content of 5%.

  Next, the obtained master batch (A1 + B) and EVOH (A1) having a water content of 0.3% were mixed with a twin-screw extruder (screw diameter 30 mm, L / D = 42, “BT-30-S2” manufactured by Plastic Engineering Laboratory). -42-L ") and melt-mixed under the following conditions to prepare an EVOH resin composition. At this time, the master batch pellet (A1 + B) and the EVOH (A1) pellet were mixed at a blending ratio (weight) of (A1 + B) / (A1) of 21/79, and then supplied from the hopper part. Moreover, 0.05 weight part (0.008 weight part in metal conversion) with respect to solid content (A1 + B) 100 weight part was supplied from the hopper part for the purpose of heat stability improvement.

[Mixing conditions]
Supply amount 25kg / hour screw configuration Normal kneading type screw
(Kneading discs are placed between C1 and C4 and between C5 and C7)
Screw rotation speed 190rpm
Strand die diameter 3.5mmφ: 3-hole vent C7 part vacuum suction temperature setting C1 70 ° C C6 230 ° C
C2 210 ° C C7 230 ° C
C3 230 ° C H 230 ° C
C4 230 ° C D 230 ° C
C5 230 ° C
Motor torque 28 Ampere

Extruded into a strand form from a strand die provided at the exit of the extruder and cut using a pelletizer to obtain EVOH resin composition pellets (water content 0.3%: diameter 2.5 mm, length 3 mm cylindrical) It was.
The content of montmorillonite (B) in the EVOH composition was 4.2 parts by weight with respect to 100 parts by weight of EVOH.

(2) Production of multilayer film Feed block obtained from EVOH resin composition pellets, polypropylene resin (PP) ("F300SP" manufactured by Prime Polypro), and adhesive resin ("ADMER QF500" manufactured by Mitsui Chemicals) It is supplied to a multi-layer extrusion apparatus equipped with three types and five layers of multi-layer T-die, and PP layer / adhesive resin layer / EVOH resin composition layer / adhesive resin layer / PP layer (200/30/60/30/200 ( μm)) multilayer film.

[Multilayer film forming conditions]
Intermediate layer extruder: 32mmφ single screw extruder (barrel temperature 230 ° C)
Upper and lower layer extruder: 40mmφ single screw extruder (barrel temperature 220 ° C)
Adhesive layer extruder: 32mmφ single screw extruder (barrel temperature 220 ° C)
Die temperature: 220 ° C
Take-off speed: 1 m / min Roll temperature: 50 ° C

(3) Production of multilayer stretched film The obtained multilayer film was preheated at 155 ° C. for 2 minutes with a tenter type biaxial stretching machine, and then stretched 7 times in length and under conditions of a stretching temperature of 155 ° C. and a stretching speed of 200 mm / sec. The film was biaxially stretched 7 times and heat-fixed for 1 minute to produce a multilayer stretched film (total thickness 15 μm, EVOH resin composition layer thickness 1.7 μm).

In addition to the above-mentioned transparency evaluation, the following evaluation was performed about the obtained multilayer stretched film.
<Oxygen barrier property evaluation>
The oxygen permeability was measured under the conditions of 23 ° C. and 80% RH using an oxygen permeability measuring device (“OXTRAN100A” manufactured by MOCON). In addition, 100% concentration oxygen gas was used as the test gas. The results are shown in Table 2.

Example 5
In Example 4, instead of EVOH (A1) as EVOH for diluting the masterbatch, the content of the structural unit (1) is 1.1 mol%, the ethylene content is 32 mol%, the saponification degree is 99.7 mol%, and MFR is 12 g. EVOH (A2) that is 10 minutes (measured at 210 ° C., 2160 g), EVOH used in the masterbatch is unmodified EVOH (ethylene content 29 mol%, saponification degree 99.7 mol%, MFR 8 g / 10 An EVOH resin composition was prepared in the same manner as in Example 4 except that the minute (measured at 210 ° C. and 2160 g) was used.
The EVOH in the EVOH resin composition at this time is a mixture of EVOH (A) containing the structural unit (1) and unmodified EVOH, and its ethylene content is 31.5 mol% and the degree of saponification is 99. 0.7 mol% and the content of the structural unit (1) was 0.92 mol%.
The content of montmorillonite (B) in the EVOH composition was 4.2 parts by weight with respect to 100 parts by weight of EVOH.
Next, using this EVOH resin composition, a multilayer film and a multilayer stretched film were produced and evaluated in the same manner. The results are shown in Table 2.

Example 6
In Example 5, an EVOH resin composition was produced in the same manner except that the blending ratio of the master batch pellet and EVOH (A2) was 11/89 (weight ratio).
The EVOH in the EVOH resin composition at this time is a mixture of EVOH (A) containing the structural unit (1) and unmodified EVOH, and its ethylene content is 31.7 mol% and the degree of saponification is 99. 0.7 mol% and the content of the structural unit (1) was 1.0 mol%.
Next, using this EVOH resin composition, a multilayer film and a multilayer stretched film were produced and evaluated in the same manner. The results are shown in Table 2.
The content of montmorillonite (B) in the EVOH composition was 2.1 parts by weight with respect to 100 parts by weight of EVOH.

Comparative Example 4
In Example 5, instead of EVOH (A2) as EVOH for diluting the masterbatch, ethylene content was 32 mol%, saponification degree was 99.7 mol%, MFR was 12 g / 10 min (measured at 210 ° C. and 2160 g), unmodified An EVOH resin composition was similarly prepared except that EVOH was used.
EVOH in the EVOH resin composition at this time was a mixture of unmodified EVOHs, and its ethylene content was 31.5 mol% and the degree of saponification was 99.7 mol%.
The content of montmorillonite (B) in the EVOH composition was 4.2 parts by weight with respect to 100 parts by weight of EVOH.
Next, using this EVOH resin composition, a multilayer preform and a multilayer bottle were prepared and evaluated in the same manner. The results are shown in Table 2.

Comparative Example 5
In Example 5, instead of EVOH (A2) as EVOH for diluting the masterbatch, the same ethylene content as EVOH for the masterbatch was 29 mol mol%, the saponification degree was 99.7 mol%, the MFR was 8 g / 10 min (210 ° C). An EVOH resin composition was prepared in the same manner except that unmodified EVOH (measured at 2160 g) was used.
The content of montmorillonite (B) in the EVOH composition was 4.2 parts by weight with respect to 100 parts by weight of EVOH.
Next, using this EVOH resin composition, a multilayer preform and a multilayer bottle were prepared and evaluated in the same manner. The results are shown in Table 2.

[Table 2]

Claims (8)

It is formed by stretching a multilayer film having at least one layer containing an ethylene-vinyl alcohol copolymer (A) having the following structural unit (1) and a water-swellable layered inorganic compound (B). A multilayer stretched film.

(Wherein R ¹ represents hydrogen or an organic group, X represents a bonding chain, n represents 0 or 1, and R ^{2 to} R ⁴ each represent hydrogen or an organic group) R ¹ of the structural unit (1) in the ethylene-vinyl alcohol copolymer (A) is a hydrogen atom, n is 0, and R ^{2 to} R ⁴ are all hydrogen atoms. The multilayer stretched film according to claim 1.   The multilayer stretched film according to claim 1 or 2, wherein the content of the structural unit (1) in the ethylene-vinyl alcohol copolymer (A) is 0.1 to 30 mol%. The multilayer stretched film according to claim 1, wherein the water-swellable layered inorganic compound (B) is montmorillonite. The content of the water-swellable layered inorganic compound (B) is 0.5 to 100 parts by weight with respect to 100 parts by weight of the ethylene-vinyl alcohol copolymer. Multilayer stretched film. The multilayer stretched film according to claim 1, wherein the layer containing the ethylene-vinyl alcohol copolymer (A) and the water-swellable layered inorganic compound (B) has a thickness of 0.5 to 30 μm. . The multilayer stretched film according to any one of claims 1 to 6, wherein the stretched film is stretched so as to have an area ratio of 2 to 80 times. The multilayer stretched film according to any one of claims 1 to 7, wherein the haze is 10 or less.