JP3371028B2 - Manufacturing method of multilayer structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention does not contain bubbles such as voids even when extruded at a high temperature, enables high-speed processing, and has an adhesive force between the saponified ethylene-vinyl ester copolymer and the adhesive resin. The present invention relates to a good method for producing a multilayer structure, particularly a multilayer film, by a coextrusion coating method.

[0002]

2. Description of the Related Art Conventionally, biaxially oriented polypropylene film (hereinafter referred to as OPP) and biaxially oriented polyamide film (hereinafter referred to as OP) which are excellent in transparency, mechanical strength, and price.
A) and a base film such as a biaxially stretched polyethylene terephthalate film (hereinafter abbreviated as PET) are laminated with a polyolefin film for the purpose of imparting heat-sealing property, and are used for various purposes such as food and medicine. It is used as a packaging material for various purposes. However, since these films do not have good gas barrier properties, oxygen entering the bag from the outside may cause mold to grow on the contents, volatilize the contents, oxidize fats and oils, and change the flavor. It is easy to get rid of, the storage stability of the contents is poor, and improvement of the gas barrier property is desired.

As a method of improving the gas barrier property, a solution of vinylidene chloride / methyl methacrylate copolymer latex or vinylidene chloride / acrylonitrile copolymer is used.
It is coated on the various films (referred to as PVDC coated film and sold by various companies), a film of saponified ethylene-vinyl ester copolymer (hereinafter referred to as EVOH) or polyvinyl alcohol (hereinafter referred to as P).
This is possible by laminating a film (abbreviated as VA) and the above various films. However, the PVDC coated film has a drawback that it is yellowish as it is, and it is further yellowed by ultraviolet rays. Furthermore P
The VDC-coated film has a serious drawback that it is significantly inferior in bending resistance and pinholes are generated during transportation, which impairs gas barrier properties.

On the other hand, the dry laminated product of OPP and EVOH or PVA film is colorless and transparent, and there is no fear of yellowing even with ultraviolet rays, but it is inferior in bending resistance and easily causes delamination when boiled at high temperature. Moreover, there is a drawback that the manufacturing cost becomes high.

Japanese Unexamined Patent Publication (Kokai) No. 51-18775 discloses a method for producing a laminated film, which comprises at least two layers of a base film, one layer of which is EVOH and a thin film melt is pressure-bonded thereto. Stated. However, the invention relates to EVOH to be used,
"Be careful when using a material with poor thermal stability due to impurities or other factors, which may cause foaming or fisheyes, which may seriously affect gas permeation resistance. "Because the heat resistance is poor, the melting temperature must be 250 ° C or lower. ] Is described. However, this publication does not describe a formulation that enables extrusion at a higher temperature, and extrusion at a high temperature improves high-speed processing due to improvement in the spreadability of EVOH.
The adhesive strength between the adhesive resin and the adhesive resin, thin the EVOH layer,
There is no description about enabling improvement of the film surface by reducing unmelted EVOH.

Japanese Patent Publication No. 2-37298 discloses a resin containing at least 10 to 100% by weight of EVOH,
A resin containing 30% by weight or more of a polyethylene resin is extrusion-laminated so that the resin containing the polyethylene resin is laminated on one surface to form an extrusion laminate, and then extrusion lamination of the extrusion laminate. Immediately after that, at least the surface portion is subjected to ozone treatment by blowing a gas containing ozone onto the surface of the resin layer containing the polyethylene-based resin in a molten state, and then the above-mentioned extrusion laminate and the anchor coat on the surface. Separately treated base sheet that has been treated is laminated so that the former ozone-treated surface and the latter anchor coat-treated surface face each other, and the method for producing a laminate characterized by pressing and cooling is described. Has been. However, the publication also states that "EVOH decomposes when heated to a high temperature, so that
It is necessary to process in the following. ] Is described. However, this publication also does not describe a formulation that enables extrusion at higher temperatures and the effect of extrusion at high temperatures.

In Japanese Patent Laid-Open No. 3-75120, an oxygen barrier resin and an adhesive resin are coextruded on a laminated film composed of a polyester film and an adhesive resin layer, and the adhesive resin is used as the adhesive resin for the laminated film. It describes a method for producing a laminate, characterized in that the layers are superposed on one another and coextrusion laminated. However, the publication also states that "EVOH
In this case, it is preferable to carry out at a temperature within the range of 180 to 240 ° C. ] Is described. In European Patent Publication No. 504808, EVOH and density 0.9 / c
It is described that a base film is co-extrusion coated with an adhesive ethylene-based polymer of m ³ or less to obtain a multilayer film excellent in bending resistance and interlayer adhesion. There is no description of the processing method that enables extrusion by. Japanese Unexamined Patent Publication (Kokai) No. 64-66262 describes obtaining an EVOH composition containing vinegar roots, alkali metal ions, and alkaline earth metal ions with less generation of gels and spots. There is no description of coextrusion coating the adhesive resin.

[0008]

As described above, the EVOH is
EVO for coextrusion lamination of
Due to the limitation of the extrusion temperature of H, there is a problem in speeding up at high temperature, and there is a coextrusion laminated product that does not contain bubbles such as voids even if it is extruded at high temperature and has good adhesion between EVOH and adhesive resin. Coveted.

The present invention, however, was devised in order to solve the above-mentioned drawbacks of the prior art. Even when it is extruded at a high temperature, it does not contain voids such as voids and can be processed at a high speed. It is an object of the present invention to obtain a coextrusion-coated multi-layer structure, particularly a multi-layer film, which has a good adhesive force between the adhesive resin and the adhesive resin.

[0010]

The above object is to obtain an EVOH having a thermal decomposition behavior represented by the following characteristic value (P value).
(A) and adhesive polyolefin resin (B) (hereinafter APO
Abbreviated) are co-extrusion coated onto the substrate (C). P value: A melt indexer having a nozzle with an inner diameter of 2 mmφ and a length of 1 cm and a cylinder with an inner diameter of 9.5 mmφ was heated to 300 ° C., and the sample resin (EVO
H) Put 5g and immediately apply 2.16kg load to 1g
The sample resin was discharged from the nozzle, the load was removed, the nozzle was blocked, and the time (P value) until the piston was lifted by 5 mm by applying a load of 480 g was 45 seconds or more and within 15 minutes.

The present invention will be described in more detail below. In the present invention, EVOH (A) means ethylene and vinyl ester, a polymerization initiator such as benzoyl peroxide and azobisisobutyronitrile under pressure in a solvent such as methanol, t-butanol or dimethylsulfoxide. It is a polymer obtained by polymerizing by a known method, followed by saponification with an acid or alkali catalyst. Examples of the vinyl ester include aliphatic vinyl esters such as vinyl acetate, vinyl propionate, vinyl versatate and vinyl pivalate,
Aromatic carboxylic acid vinyl esters can also be used. Among these vinyl esters, vinyl acetate is preferred in terms of price. The ethylene content of EVOH is 20 to 65 mol%, preferably 25 to 50 mol%,
The saponification degree of the vinyl ester component is 90 mol% or more, preferably 95 mol% or more. When the ethylene content is less than 20 mol%, the gas barrier property at high humidity is deteriorated, and 6
If it exceeds 5 mol%, sufficient gas barrier properties cannot be obtained. On the other hand, when the saponification degree is less than 90 mol%, not only the gas barrier property at high humidity is deteriorated but also the thermal stability of EVOH is deteriorated, and gel is apt to be generated on the obtained film surface.

Further, EVOH contains a small amount of propylene, isobutene, 4-methylpentene-1, hexene,
Α-olefins such as octene, unsaturated carboxylic acids such as itaconic acid, methacrylic acid, acrylic acid, maleic acid, salts thereof, partial or complete esters thereof, nitriles thereof, amides thereof, anhydrides thereof, vinyltrimethoxysilane, etc. It does not matter even if it contains a copolymerization component such as a vinylsilane compound, an unsaturated sulfonic acid, a salt thereof, an alkylthiol, and N-vinylpyrrolidone.

EVOH may be a mixture of two or more kinds of EVOH having different ethylene contents, and
It may be a mixture of two or more kinds of EVOH having different degrees of polymerization and saponification. Further, the ethylene content and the degree of polymerization or the degree of saponification may be different. Furthermore, EV
OH layer has two or more EVs with different ethylene contents
It may be a multilayer body of OH.

In addition, EVOH may be an antioxidant, a colorant, an ultraviolet absorber, a slip agent, an antistatic agent, a plasticizer, a cross-linking agent such as boric acid, an inorganic filler, an inorganic agent, etc. You may mix | blend various additives, such as a desiccant, and various resins, such as polyamide, polyolefin, and a superabsorbent resin.

In the present invention, the method for measuring the P value, that is, the method for measuring the piston rising speed of the melt indexer is as follows: a nozzle having an inner diameter of 2 mmφ, a length of 1 cm, and an inner diameter of 9.
Melt indexer (J
ISK7210; Melt Indexer L manufactured by Takara Industry Co., Ltd.
(Type 203) is heated to 300 ° C., 5 g of the sample resin is put into the cylinder, 2.16 kg of load is immediately applied to discharge 1 g of the resin from the nozzle, and then the load is removed. Immediately after that, the outlet of the nozzle is blocked (for example, Insert a wire of 2 mmφ in the direct line into the nozzle to close it, and then apply a load of 480 g,
Start the stopwatch and measure the time it takes for the piston to rise 5 mm.

It is important that the P value is in the range of 45 seconds or more and 15 minutes or less, preferably 1 minute or more and 15 minutes or less, more preferably 1 minute or more and 10 minutes or less, further preferably 2 minutes or more. Within 10 minutes. Even if the P value is less than 45 seconds, at the normal extrusion temperature, the EV obtained by coextrusion coating
The OH layer has a good film surface, but when the extrusion temperature is raised to perform high-speed processing for the purpose of improving productivity, the EVOH layer obtained by coextrusion coating is caused by the thermal decomposition of EVOH. The film is likely to contain bubbles, resulting in poor appearance. On the other hand, if it exceeds 15 minutes, adhesive resin and EVOH
The adhesive strength of is likely to decrease.

EVOH (A) used in the present invention is typically obtained by the following method. That is, the volatile content {based on the weight loss rate (dry basis) when EVOH at 20 ° C. is dried at 120 ° C. for 24 hours is the volatile content} is 0.3% or less, preferably 0.2% or less, more preferably Is dried to 0.15% or less, and acid radical 70 to 2000 pp
m, preferably 70 to 1000 ppm, more preferably 10
0-1000ppm, alkali metal ion 15-400
ppm, preferably 20-300 ppm, more preferably 3
0-200ppm, alkaline earth metal ion 10-30
It is obtained by containing 0 ppm, preferably 30 to 200 ppm, and more preferably 50 to 150 ppm. When the alkali metal ion is 100 ppm or more, the alkaline earth metal ion may be contained in a small amount or may not be contained, and when the alkaline earth metal ion is 50 ppm or more, the alkali metal ion may be contained in a small amount or not contained. May also be good.

The acid radical is preferably pKa (25 ° C.).
Acidity index of 3.5 or more) such as acetic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, citric acid, lauric acid, oleic acid, stearic acid, behenic acid, benzoic acid, aspartic acid, aminobenzoic acid An acid, an organic acid such as glutamic acid, an inorganic acid such as boric acid from which a hydrogen atom is removed, and is added as a compound such as an acid, an acid anhydride or a metal salt. Examples of other acid radicals include phosphate radicals such as inorganic acid substances such as potassium dihydrogen phosphate and sodium dihydrogen phosphate. Examples of the alkali metal ion include lithium ion, sodium ion, potassium ion, and the like, and examples of the alkaline earth metal ion include magnesium ion, calcium ion, barium ion, and the like. The metal ion is added as a compound such as carbonate, acetate, phosphate, sulfate, nitrate, borate, hydroxide or chloride.

When it is added with sodium carbonate, it contains only sodium ions, but when it is added with a metal salt such as sodium acetate, calcium acetate, potassium dihydrogen phosphate or sodium dihydrogen phosphate, the acid radical and the metal are included. Since both ions are included, it is necessary to calculate each value.

In the present invention, APO (B) is a polymer of an olefin having 2 to 8 carbon atoms such as ethylene, propylene and butene-1, which has been modified with an unsaturated carboxylic acid such as maleic anhydride. Examples thereof include copolymers of two or more kinds of olefins different from each other, and copolymers of these olefins with other comonomers. These APOs may be used alone, or may be used by blending the (co) polymer not modified with maleic anhydride or the like. Further, two or more kinds of APO may be blended and used. Further, various additives such as an antioxidant, a colorant, an ultraviolet absorber, a slip agent, an antistatic agent, a plasticizer, a cross-linking agent, an inorganic filler, and an inorganic desiccant are added to these APOs within a range that does not hinder the present invention. Various resins such as thermoplastic resins may be blended.

The base polyethylene used for APO includes high-density polyethylene which is a homopolymer of ethylene, medium-density polyethylene, low-density polyethylene, and propylene, butene-1, which contains ethylene as a main component.
4-methylpentene-1,1-hexene, 1-octene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, styrene, vinyl acetate, methyl acrylate, ethyl acrylate, acrylic acid, methyl methacrylate , Ethyl methacrylate, methacrylic acid, glycidyl methacrylate, maleic anhydride, itaconic anhydride and the like copolymers, among the copolymers of ethylene and acrylic acid or methacrylic acid is sodium, An ionomer crosslinked with zinc, aluminum or the like may be used, and in the copolymer of ethylene and vinyl acetate, part or all of the vinyl acetate component may be saponified. APO is obtained by graft-modifying these base polyethylene with an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, itaconic acid anhydride, maleic acid anhydride, or a salt or ester thereof. However, those containing an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic anhydride, itaconic anhydride in the main chain is an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, itaconic anhydride, maleic anhydride, It may be graft-modified with a salt or its ester, or may not be graft-modified.

The polypropylene used for APO includes homopolymers of propylene and ethylene, butene-1, pentene-1, 4 containing propylene as a main component.
-Methylpentene-1, hexene-1, octene-1,
5-ethylidene-2-norbornene, 5-methylene-2
-Norbornene, 1,4-hexadiene, copolymers with styrene, etc., graft-modified with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic anhydride, maleic anhydride, salts thereof or esters thereof Can be mentioned.

The polybutene-1 used for APO includes homopolymer of butene-1, and ethylene, propylene, butene-2, isobutylene, butadiene, pentene-1,4-methylpentene containing butene-1 as a main component. 1, copolymers with hexene-1, octene-1, etc., and those graft-modified with a carboxylic acid such as acrylic acid, methacrylic acid, itaconic anhydride, maleic anhydride, or a salt or ester thereof. .

In the present invention, the total thickness of the EVOH layer is a μm, and the total thickness of the APO layer is b μm.
When the thickness of one O layer is b'μm, it is preferable to satisfy the following formula. 0.5 ≦ a ≦ 20, 0.5 ≦ b ′ ≦ 20, 1 ≦ a + b ≦
30 preferably 0.5 ≦ a ≦ 15, 0.5 ≦ b ′ ≦ 15, 1
≦ a + b ≦ 25 More preferably 1 ≦ a ≦ 10, 1 ≦ b ′ ≦ 1
0, 2 ≦ a + b ≦ 20

The total thickness (a) of the EVOH layer is 0.5
When it is in the range of up to 20 μm, a multilayer film having excellent gas barrier properties and bending resistance can be obtained. Further, according to the present invention, since the thickness (a) of the entire EVOH layer can be reduced, it is possible to reduce the amount of expensive EVOH used and it is economical. When the thickness (b ′) per one layer of the APO layer is in the range of 0.5 to 20 μm, E
Sufficient interlayer adhesion with VOH can be obtained, and a multilayer film having excellent transparency can be obtained. Further, the total thickness (a + b) of the EVOH layer and the APO layer is
When it is in the range of 1 to 30 μm, the stability of the melts of (A) and (B) is good, the occurrence of film breakage is small, and a multilayer film excellent in bending resistance is obtained. By satisfying all of these conditions, it becomes possible to obtain a multi-layered film having productivity, economy, strength and the like.

To obtain such a coextrusion coating film having a uniform thickness distribution in the width direction of each layer and all layers, EVO
H (of blend if EVOH is blend)
Melting index (according to JIS K 7210, temperature 230
Weight discharged from a nozzle having an inner diameter of 2 mm at a temperature of 2.16 kg for 10 minutes. Hereafter referred to as MFR) ηEg /
10 minutes, similarly, when the MFR of APO is ηAg / 10 minutes, it is preferably within the following range. 1 ≦ ηE ≦ 80, 1 ≦ ηA ≦ 80, 0.08 ≦ ηE / η
A ≦ 8 Preferably 2 ≦ ηE ≦ 70, 2 ≦ ηA ≦ 60, 0.1
≦ ηE / ηA ≦ 5, more preferably 3 ≦ ηE ≦ 50, 3 ≦ ηA ≦ 40, 0.
2 ≦ ηE / ηA ≦ 3. When ηE and ηA are in the range of 1 to 80, a coextrusion coating film having a small increase in neck-in width and a uniform thickness distribution can be obtained. Also, ηE /
When ηA is in the range of 0.08 to 8, the occurrence of thickness unevenness in the width direction is small in the coextrusion coating film, and it is also possible to prevent appearance defects due to wood grain patterns or satin finish.

In the present invention, the constitution of the molten multilayer body composed of EVOH and APO is EVOH / APO, APO / E.
VOH / APO, EVOH / APO / EVOH, EVO
H / APO / EVOH / APO, etc., and a molten multilayer body with other thermoplastic resin, for example EVOH / A
PO / thermoplastic resin, APO / EVOH / thermoplastic resin, APO / EVOH / APO / thermoplastic resin, EVO
H / APO / EVOH / thermoplastic resin etc. are mentioned. Either side of EVOH or APO of the molten multilayer body may be laminated on the substrate (C), and before being laminated on the substrate,
One or both surfaces of the molten multilayer body and / or the substrate may be treated with ozone or corona.

Here, as the thermoplastic resin, a raw material thermoplastic resin used for a sealant (heat sealant) described later and a thermoplastic resin used for a base material (C) described later can be used.

In the present invention, examples of the base material (C) to be co-extrusion coated include polyolefins such as high, medium and low density polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, poly ε-caprolactam and polyhexa. Polyethylene such as methylene adipamide, polymethaxylylene adipamide, polyvinylidene chloride, polystyrene, polyacrylonitrile, unstretched film made of thermoplastic resin such as polycarbonate, uniaxially stretched film, biaxially stretched film, rolled film or sheet Other suitable materials include papers such as kraft paper and carton paper, cellophane, and aluminum foil. The substrate, particularly the substrate film, may be vapor-deposited with metal or metal oxide, or may be printed,
An anchor coating agent may be applied, or two or more kinds of those treatments may be applied. From the viewpoint of strength and economy, the thickness of the base material (C) is preferably set in the range of 10 to 1000 μm, particularly 10 to 200 μm, further 10 to 100 μm, and further 15 to 60 μm.

[0030] The use of substrates in the present invention (C) as at least one surface adhesion of the applied resin laminate having a (M-TR) layer (C), the adhesion between the layer (B) It is preferable because it is further improved. Where MT
The laminate (C) having an R layer is selected from various resins, in particular, at least one surface of various thermoplastic resin layers, selected from polypropylene copolymer, butene-based polymer, polyethyleneimine, and modified cellulose as M-TR. It is a laminate of the polymer and the like. Here, as the M-TR, for example,
(C) / (B) / (A) with 2 layers
T peel test was conducted under conditions of 0 ° C., relative humidity 65%, chuck distance 50 mm, and pulling speed 250 mm / min.
The adhesive strength cannot be measured due to material destruction between the layers (C) and (B), or the adhesive strength is 70 g / 15 mm width or more, preferably 100 g / 15 mm width or more, more preferably 150 g / 15 mm width or more. preferable.
On one side or both sides of the laminate (C) having the M-TR layer,
Surface treatment such as corona discharge treatment, chromic acid treatment, flame treatment, ozone treatment, sandblast treatment, vacuum deposition treatment of aluminum or aluminum oxide, etc. may be performed.
The base of the substrate is a polypropylene film, particularly a biaxially oriented polypropylene film (OPP), for example, an OPP having a stretching area ratio of 10 times or more, preferably 18 times or more.
Are preferable because they improve the strength such as tensile strength and printability. Further , the thickness of the M-TR layer is preferably set in the range of 0.01 to 15 μm, particularly 0.1 to 10 μm from the viewpoint of adhesiveness and economical efficiency. M-TR layer of laminate (C)
The surface is laminated so as to be adjacent to the layer (B).

The propylene copolymer of M-TR means chlorinated polypropylene, propylene as a main component, ethylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, Copolymers with 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 1,4-hexadiene, styrene, etc., and graft-modified products with carboxylic acids such as maleic anhydride, and blends thereof. Or a blend of these propylene copolymers and propylene homopolymers. Such a propylene copolymer has a melting point of 10 ° C. or higher than that of the base material OPP, preferably 15
It is preferable that the temperature is not lower than 0 ° C, more preferably not lower than 20 ° C in order to obtain the effects of the present invention sufficiently.

The butene-based polymer of M-TR is
Butene-1 homopolymer, butene-1 as a main component, ethylene, propylene, butene-2, isobutylene, butadiene, pentene-1, 4-methylpentene-
1, hexene-1, copolymers and blends thereof with octene-1, etc., or a blend of a homopolymer or the propylene copolymer of butene-based polymers and propylene.

Polyethyleneimine of M-TR is a polymer of aziridine, or a binary copolymer of aziridine and its derivative and / or a comonomer copolymerizable with aziridine, and a polymer which can be added thereto. It is a polymer to which a comonomer is added.

The modified cellulose of M-TR is
It is an ester of cellulose, and typical examples thereof include cellulose acetates such as cellulose triacetate and cellulose diacetate, and nitrocellulose.

In the present invention, a biaxially oriented polypropylene film, a propylene copolymer, a butene-based polymer, and a polyethyleneimine, which are laminated to impart adhesiveness,
There is no particular limitation on the method of laminating with a polymer selected from modified cellulose, and a multilayer sheet obtained by coextruding polypropylene as a raw material of a biaxially oriented polypropylene film and the polymer may be biaxially oriented. A multilayer sheet obtained by laminating the polymer on a polypropylene sheet which is a raw material of a biaxially oriented polypropylene film by an extrusion laminating method or a solution coating method may be biaxially oriented, or a biaxially oriented polypropylene film may be obtained. The polymer may be laminated by an extrusion laminating method or a solution coating method. When printing is applied to such a biaxially oriented polypropylene film,
It is preferable to laminate a polymer for imparting adhesiveness to the printed surface. By using the biaxially oriented polypropylene film (C) having such adhesiveness, the adhesiveness between the (B) layer and the (C) layer is remarkably improved, and the boil resistance and the pinhole resistance are improved. Greatly improved. As the polymer to be laminated for imparting adhesiveness, a propylene copolymer or a butene-based polymer is particularly preferable in order to sufficiently obtain the effects of the present invention.

Further, in the present invention, a sealant may be laminated on at least one surface of the coextrusion-coated film. As the laminated sealant, polypropylene, polyethylene, polyester, polyamide,
Examples thereof include polyacrylonitrile, which may be used alone, may be used by blending two or more kinds, or may be used in a multilayer body, but may have a lower melting point or a lower softening point than the base film. Preferably there is. Especially the Vicat softening point (JISK7206) is 15 ℃
As described above, it is preferable to use a sealant layer made of a thermoplastic resin whose temperature is preferably 25 ° C. or more.

The polypropylene used for the sealant is a homopolymer of propylene, and ethylene, butene-1,5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 1,4-containing propylene as a main component. Examples thereof include copolymers with hexadiene and the like, and also those graft-modified with a carboxylic acid such as maleic anhydride or a salt or ester thereof.

As polyethylene used for the sealant, high density polyethylene which is a homopolymer of ethylene, medium density polyethylene, low density polyethylene, and propylene, butene-1 containing ethylene as a main component,
4-methylpentene-1,1-hexene, 1-octene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, vinyl acetate, methyl acrylate,
Ethyl acrylate, acrylic acid, methyl methacrylate,
Examples thereof include copolymers with ethyl methacrylate and methacrylic acid. Among the copolymers, the copolymer with acrylic acid or methacrylic acid may be crosslinked with sodium, zinc, aluminum or the like, and the copolymer with vinyl acetate may be a part of the vinyl acetate component or All may be saponified. Further, the polyethylene may be graft-modified with a carboxylic acid such as maleic anhydride, a salt thereof or an ester thereof.

Further, as the polyester used for the sealant, ethylene glycol, diethylene glycol, trimethylene glycol, propylene glycol,
1,4-butanediol, neopentyl glycol,
1,4-cyclohexanedimethanol, 4,4'-dihydroxydiphenyl-2,2-propane, glycerin,
Polyhydric alcohol components such as pentaerythritol, parahydroxybenzoic acid, δ-valerolactone, ε-caprolactone, hydroxycarboxylic acid components such as tartaric acid, terephthalic acid, isophthalic acid, various naphthalene dicarboxylic acids, azelaic acid, sebacic acid, Examples include polyvalent carboxylic acids such as pimelic acid, adipic acid, geltaric acid and succinic acid, and polyesters obtained from the ester component thereof as a raw material.

Furthermore, as the polyamide used for the sealant, hexamethylenediamine, piperazine,
Diamine components such as tetramethylenediamine, ethylenediamine, and metaxylylenediamine, and δ-valerolactam, ε-caprolactam, ω-laurolactam, ω-
Aminocarboxylic acid components such as aminoundecanoic acid and ω-aminododecanoic acid, and various polycarboxylic acids such as naphthalene dicarboxylic acid, terephthalic acid, isophthalic acid, azelaic acid, sebacic acid, pimelic acid, adipic acid, glutaric acid, and succinic acid. Examples thereof include polyamide obtained from an acid component as a raw material.

Furthermore, examples of the polyacrylonitrile used in the sealant include copolymers containing acrylonitrile as a main component and styrene, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butadiene and the like. Further, the sealant or the base film, in the range that does not hinder the present invention, an antioxidant, a colorant, an ultraviolet absorber, a slip agent, an antistatic agent, a plasticizer, a crosslinking agent, an inorganic filler, an inorganic desiccant. You may mix | blend various additives, such as, and various resins, such as a thermoplastic resin. The thickness of the sealant layer is appropriately selected depending on the weight of the content, but a range of 15 to 150 μm is suitable.

Substrate (C), especially substrate film, EVO
As a method for laminating the H (A) layer, the APO (B) layer, and the sealant, it is basically necessary to coextrusion-coat the base film with the molten multilayer body of the (B) layer and the (A) layer. The sealant film may also be coextrusion coated at the same time. Further, the substrate may be co-extrusion coated with the molten multilayer body of the layer (B) and the layer (A), and then extrusion-laminated with a sealant, or (an anchor coating agent may be used in each step, The anchor coat material may be used in only one step, or the anchor coat material may not be used in both steps), and the base material is coextrusion coated with the molten multilayer body of layer (B) and layer (A). (Anchor coat material may be used), and subsequently, sealant film may be dry laminated.

In the present invention, the extrusion temperature of EVOH is
Extruder tip temperature is 220 ° C or higher, more preferably 225
℃ or more, more preferably 230 ℃ or more, more preferably 240 ℃ or more. There is no upper limit on the extrusion temperature, and it depends on the residence time of EVOH in the extruder, but it is 30
It can be raised to about 0 ° C. By extruding at such a high temperature, 110 m / min or more, especially 125 m / min.
Min or more, further 130 m / min or more, further 150 m /
It is possible to extrude a thin layer of EVOH at a high speed of not less than a minute. There is no particular upper limit on the speed, but the speed can be increased to about 250 m / min, or even about 300 m / min. Further, by extruding at a high temperature, not only the adhesive strength between APO and EVOH is improved, but also the productivity is improved by increasing the speed, and the gas barrier property is also improved. In order to perform high-speed extrusion processing, it is necessary to perform extrusion processing at a higher temperature, and it is difficult to raise the temperature to a high temperature in the conventional method because bubbles and the like are generated at a higher temperature, which makes high-speed extrusion processing difficult. The industrial significance of solving these problems by the present invention is great.

The coextrusion-coated film thus obtained has good adhesion between EVOH and APO, does not contain bubbles such as voids even when extruded at high temperature, and can be used for various food products.
It can be suitably applied to medicines, industrial chemicals, cosmetics and the like.
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. All parts and% are based on weight unless otherwise specified.

[0045]

EXAMPLE 1 A 25 μm-thick OPP {Tocello HC-OP manufactured by Tokyo Cellophane Paper Co., Ltd. } was used as M-TR on one side of the polypropylene.
Ethylene content in the laminate obtained by laminating Nko polymer 32 mole%, saponification degree 99.5 mol% of a vinyl acetate component, P value of 6 minutes (sodium ions 9 ppm, calcium ion 6
5 ppm, acetate radical 870 ppm, phosphate radical 10 ppm, volatile matter 0.1%) EVOH was melted to 270 ° C. , and APO {Mitsui Petrochemical Industrial Co., Ltd. ADMER
SF600 (polyethylene adhesive resin)} at 270 ° C
And EVOH thickness of 5 μm, APO thickness of 2 μm, co-extrusion coating was performed at 130 m / min so that APO was in contact with the M-TR surface of OPP, and the co-extrusion of OPP laminate / APO / EVOH composition was performed. A multilayer film was obtained by extrusion coating, subsequently 0.2 g / m ² of an anchor coating agent was applied as a solid content on the EVOH surface, the solvent was evaporated at 70 ° C., and then low density polyethylene was used as a sealant {Mitsui Petrochemical Industry ( MILASON 11 manufactured by Mitsui Chemicals Co., Ltd. is melted at 320 ° C., extrusion laminated on the EVOH surface with a thickness of 20 μm, and finally low density polyethylene manufactured by Mitsui Petrochemical Industry Co., Ltd.
Melathon 11} is melted at 290 ° C. and has a thickness of 40 μm.
A laminated film was obtained by extrusion laminating on a low density polyethylene surface extruded at 320 ° C. The P value is 6 minutes E
VOH is sodium dihydrogen phosphate, calcium acetate,
It was obtained from EVOH containing sodium acetate.

The oxygen barrier property of the laminated film was 1.4.
m1 / m ² · day · atm (Modern Control Co., Ltd.
Using OX-TRAN 10/50 type, 20 ° C., 65
% RH), no bubbles were generated in the EVOH layer, and the appearance was good. APO and EVOH
The lamination strength of (T type peeling, speed 250 mm / min,
Sample width 15 mm) is also 270 g / 15 mm width or more (OPP and APO are separated at 270 g / 15 mm width first, so the lamination strength of APO and EVOH is 270 g / 1.
There was more than 5 mm width).

Comparative Example 1 In Example 1, the P value was 3 seconds (sodium ion 10
0ppm, calcium ion 150ppm, acetate 20
A laminated film was obtained under the same conditions as in Example 1 except that EVOH containing ppm and having a volatile content of 0.3%) was used.
Bubbles were generated in the EVOH layer, resulting in poor appearance. The EVOH having a P value of 3 seconds was obtained from EVOH containing sodium acetate and calcium acetate.

Comparative Example 2 In Example 1, the P value was 18 minutes (potassium ion 10
ppm, calcium ion 5 ppm, acetate 50 pp
m, a phosphoric acid radical of 20 ppm, and a volatile content of 0.05%) except that the EVOH was changed to obtain a laminated film under the same conditions as in Example 1. Appearance was good, but APO and E
The VOH laminate strength was as small as 30 g / 15 mm width, which was a problem. It should be noted that EVOH with a P value of 18 minutes
Is obtained from EVOH containing potassium dihydrogen phosphate, calcium acetate, acetic acid.

Comparative Example 3 15 μm thick OPA {Bonil R manufactured by Kojin Co., Ltd.}
In addition, the ethylene content was 47 mol%, the saponification degree of the vinyl acetate component was 99.5 mol%, and the P value was 30 seconds (calcium ion 3
20ppm, acetate 400ppm, volatile content 0.0
6%) EVOH is melted at 250 ° C., APO {maleic anhydride graft-modified ethylene-propylene copolymer, density 0.89 g / cm ↑ 3} is melted at 240 ° C., EVOH thickness is 4 μm, and APO Co-extrusion coating was performed at 120 m / min so that APO was in contact with OPA at a thickness of 4 μm to obtain a multi-layer film by co-extrusion coating having an OPA / APO / EVOH structure. 0.2 g / m ² was applied as, after evaporation of the solvent at 70 ° C., low-density polyethylene {Mitsui Petrochemical Industries, Ltd. Mirason 11} was melted in 320 ° C. as sealants, EVOH with thickness 20μm
Layer is extruded and laminated, and finally low density polyethylene {Mirason 11 manufactured by Mitsui Petrochemical Industry Co., Ltd.} is melted at 290 ° C., and extrusion laminated to a low density polyethylene surface extruded at 320 ° C. with a thickness of 40 μm to form a laminated film. Obtained.
The EVOH having a P value of 30 seconds was obtained from EVOH containing calcium acetate.

The oxygen barrier property of the laminated film is 13 m.
It was 1 / m ² · day · atm, and no bubbles were generated in the EVOH layer, and the appearance was good. APO and EV
Lamination strength of OH is also 270 m / 15 mm width or more (OPA and APO are separated at 270 g / 15 mm width first, so laminating strength of APO and EVOH is 270 g / 1
There was more than 5 mm width). However, although a higher speed processing was tried, a melted film was cut off, which was a problem in terms of high speed processing. Therefore, we tried to perform high-speed processing by raising the temperature of EVOH and APO to 270 ° C, but even at a high-speed processing of 130 m / min, the molten film was not broken, but bubbles were generated in the EVOH layer. It was bad.

Example 2 PET having a thickness of 12 μm {H-5 manufactured by Diafoil Co., Ltd.
00} with anchor coating agent as solid content of 0.2 g / m
^After coating ² and evaporating the solvent at 70 ° C., the ethylene content is 44 mol%, the saponification degree of the vinyl acetate component is 99.5 mol%, the P value is 3 minutes (sodium ion 200 ppm, acetic acid group 200 ppm are included, volatile matter 0.1% of EVOH is melted to 250 ° C., and APO is manufactured by Sumitomo Chemical Co., Ltd.
Bondin TX8030 (polyethylene adhesive resin) } is melted at 280 ° C. to have a thickness of 10 μm, and the APO surface is subjected to ozone treatment (air having an ozone concentration of 15 g / m ³ is blown at a rate of 160 ml / m ² ). , APO
Was subjected to coextrusion coating at 140 m / min so as to come into contact with PET to obtain a PET / APO / EVOH coextrusion coated film. The EVOH having a P value of 3 minutes was obtained from EVOH containing sodium acetate.

On the EVOH surface of the coextrusion-coated film, an adhesive for dry lamination {Takelac A-385 / Takenate A-50 (manufactured by Takeda Pharmaceutical Co., Ltd. in a ratio of 6: 1)} was added as solid content of 3 g / Apply m ² and 70 ℃
After evaporating the solvent at 60 μm, a low-density polyethylene film {manufactured by Aicero Chemical Co., Ltd. Suzuron LS2
01} was laminated on the adhesive surface for dry lamination to obtain a laminated film.

The oxygen barrier property of the coextrusion-coated film was as good as 3.9 m1 / m ² · day · atm, and E
No bubbles were generated in the VOH layer, and the appearance was good. Also, the laminating strength of APO and EVOH is 330g.
/ 15 mm width was good.

Example 3 An anchor coating agent was applied as a solid content of 0.2 g / m ² to the corona-treated surface of OPP having a thickness of 20 μm (Tocello OP-U1 manufactured by Tokyo Cellophane Paper Co., Ltd.), and the solvent was applied at 70 ° C. After evaporating, the ethylene content was 32 mol%, the saponification degree of the vinyl acetate component was 99.5 mol%, the P value was 2 minutes (sodium ion 70 ppm, calcium ion 120 pp.
m, acetate root 800ppm, phosphate root 110ppm,
EVOH with a volatile content of 0.08%) was melted to 250 ° C., and APO was manufactured by Mitsui Petrochemical Industries Ltd. ADMER
SF600 (polyethylene-based adhesive resin)} 260 ° C
And melt low-density polyethylene {Mirason 11 manufactured by Mitsui Petrochemical Industry Co., Ltd.} at 320 ° C. to make a molten multilayer body having a low-density polyethylene / APO / EVOH constitution with a thickness of 5 μm, and EVOH is on the OPP surface. Coextrusion coating was performed at 130 m / min so that they would come into contact with each other, and then low-density polyethylene {Mirason 11 manufactured by Mitsui Petrochemical Industry Co., Ltd.} was melted at 280 ° C. and extrusion-laminated on a low-density polyethylene surface with a thickness of 40 μm. To obtain a laminated film. The EVOH having a P value of 2 minutes is obtained from EVOH containing disodium hydrogen phosphate, calcium acetate and acetic acid.

The oxygen barrier property of the coextrusion coated film was as good as 1.4 ml / m ² · day · atm, and E
No bubbles were generated in the VOH layer, and the appearance was good. Also, the lamination strength of APO and EVOH is 310g.
/ 15 mm width was good.

Example 4 A high-quality paper of 200 g / m ² was subjected to corona treatment, and low-density polyethylene {Mirason 11 manufactured by Mitsui Petrochemical Industry Co., Ltd.} was melted at 320 ° C. and extruded on the corona-treated surface with a thickness of 20 μm. Lamination was performed. Then ethylene content 44
Mol%, saponification degree of vinyl acetate component 99.5 mol%, P value 6 minutes (sodium ion 135 ppm, acetate root 60 p
pm, containing 40 ppm of phosphate radical, volatile content of 0.1%) E
VOH was melted at 280 ° C., APO {ADMER NF550 (polyethylene adhesive resin) manufactured by Mitsui Petrochemical Industry Co., Ltd.} was melted at 280 ° C., and each thickness 10
μm and APO was coextrusion coated at 170 m / min so that the APO was in contact with the low density polyethylene surface.
After applying 2 g / m ² and evaporating the solvent at 70 ° C., the low density polyethylene is melted at 310 ° C. and the thickness is 40 μm.
Extrusion lamination on EVOH surface with fine paper / LDP
A coextrusion coated film of E / APO / EVOH / LDPE construction was obtained. The EVOH having a P value of 6 minutes is an EVOH containing sodium hydrogen phosphate and sodium acetate.
It was obtained from.

The oxygen barrier property of the coextrusion coated film was as good as 3.8 ml / m ² · day · atm, and E
No bubbles were generated in the VOH layer, and the appearance was good. Also, the laminating strength of APO and EVOH is 350g.
/ 15 mm width was good.

Example 5 A plane O having a thickness of 20 μm and corona-treated on both sides
PP (Tokyo Cellophane Paper Co., Ltd. "Tocello OP U-
2 "), the ethylene content is 32 mol%, the saponification degree of the vinyl acetate component is 99.6 mol%, the P value is 6 minutes (sodium ion 9 ppm, calcium ion 65 ppm, acetate radical 87).
(Containing 0 ppm and 10 ppm of phosphate radicals, volatile content is 0.1%)
EVOH is melted to 250 ° C., APO {Mitsui Petrochemical Industry Co., Ltd. ADMER NF550 (polyethylene adhesive resin)} is melted to 280 ° C., and thermoplastic resin {Mitsui Petrochemical Industry Co., Ltd. ADMER Q
F551 (polypropylene adhesive resin)} at 270 ° C
The melted multilayer body of APO / EVOH / thermoplastic resin composition melted into the respective layers has a thickness of 3 μm / 5 μm / 3 μm.
Coextrusion coating was performed at 130 m / min so that the O surface was in contact with OPP to obtain a coextrusion coated film having an OPP / APO / EVOH / thermoplastic resin constitution. EVOH having a P value of 6 minutes is sodium dihydrogen phosphate,
It is obtained from EVOH containing calcium acetate and sodium acetate.

An adhesive for dry lamination {Takelac A-385 / Takenate A-50 (manufactured by Takeda Pharmaceutical Co., Ltd.) mixed at a ratio of 6: 1} was added to the OPP surface of the coextrusion-coated film at a solid content of 3 g / m ↑ 2 application, 70 ℃
After evaporating the solvent at 60 .mu.m, an ethylene-vinyl acetate copolymer film having a thickness of 60 .mu.m and a vinyl acetate component content of 5% by weight {Aisello Chemical Co., Ltd. Suzuron LE305).
Were laminated to obtain a laminated film.

The oxygen barrier property of the laminated film was 1.4.
It was good as ml / m ² · day · atm, no bubbles were generated in the EVOH layer, and the appearance was good. Also, the laminating strength of APO1 and EVOH is 280g / 15
mm width was good.

A four-sided bag having a length of 230 mm and a width of 150 mm, in which 100 ml of water was enclosed, was obtained from the laminated film. Two products of this product were polymerized and a product which was not allowed to come into contact with another bag alone was boiled at 98 ° C. for 30 minutes. No appearance change such as delamination or blocking between the bags was observed in any of the bags, and the bags had good boil resistance.

[0062]

【Example】

Example 6 Polypropylene homopolymer having a thickness of 1000 μm (melting point 168 ° C., Vicat softening point 150 ° C.) and thickness 100 μm
The bilayer coextruded sheet consisting of polybutene-1 homopolymer (M-TR) was stretched to an area magnification of 50 times, and the total 22
A substrate film (C) having a thickness of μm was obtained. EVOH (A) (Vicat softening point 180 ° C.) of ethylene content 27 mol%, saponification degree of vinyl acetate component 99.6 mol%, MFR 7.0 g / 10 min, P value 6 min, melted at 250 ° C. Sodium ion 10ppm, calcium ion 65ppm,
Acetate root 90ppm, phosphate root 10ppm, volatile matter 0.0
9%), and melted at 220 ° C., density 0.88 g / c
m ^3, MFR7.0g / 10 min of ethylene (75 wt%) in the copolymer of propylene (25 wt%) as a main component, grafted with APO (B Maleic anhydride (0.1 wt%) ) And a feed block die manufactured by Cloren Co. at a speed of 150 m / min so that the APO (B) layer is in contact with the M-TR surface of the base film (C), and (A) A multilayer constitution film was obtained in which the thickness of each of the () layer and the (B) layer was 2 μm. Also, the laminating strength of the base film and APO and APO and EVOH (T type peeling, speed 250 mm / min, sample width 15 m
In m), the material of the coat film was destroyed, which was too large to be measured. The EVOH having a P value of 6 minutes was obtained from EVOH containing sodium dihydrogen phosphate, sodium acetate and calcium acetate.

The gas barrier property of this film is 2 cc /
m ² · day · atm {made by Modern Control Co., Ltd.
Using OX-TRAN 10/50 type, the measured value at a temperature of 20 ° C. and a humidity of 65% was good}. Adhesive for dry lamination {Takelac A- manufactured by Takeda Pharmaceutical Co., Ltd.
385 and Takenate A-50 were mixed in a weight ratio of 6: 1} on the EVOH surface of the obtained multilayer constitution film as a solid content of 3 g / m ² and the solvent was evaporated at 70 ° C. Low-density polyethylene film with a thickness of 60 μm on the coated surface {Suzuron LS-2 manufactured by Aicero Chemical Co., Ltd.
10, Vicat softening point 95 ° C which is abbreviated as LDPE hereinafter}
The (heat seal layer) was laminated at a speed of 50 m / min.

This film was made into a bag having a length of 230 mm and a width of 150 mm at a side sealing temperature of 155 ° C., a bottom sealing temperature of 160 ° C. and a speed of 60 bags / min, using LDPE as a sealing layer, and 100 ml of water was put therein and sealed with an impulse sealer. I got a four-sided bag. Even when this product was boiled at 98 ° C. for 30 minutes, no change in appearance such as delamination or whitening was observed, and the product had good boil resistance. The film did not yellow even when exposed to a fluorescent lamp for 1 month.

Example 7 Instead of the APO used in Example 6, an adhesive linear low-density polyethylene having a density of 0.90 g / cm ³ and an MFR of 12 g / 10 min melted at 250 ° C. 8
5% by weight) and 4-methylpentene-1 (15% by weight) as a copolymer with maleic anhydride (0.08% by weight)
Was carried out in the same manner as in Example 6 except that APO consisting of a grafted product of.

The gas barrier property of this film is 2 cc /
It was m ² · day · atm. The base film and A
The lamination strength between PO and APO and EVOH was also good with sufficient adhesive strength due to material destruction of the coating film. Even when a film obtained by laminating LDPE on this multilayer film in the same manner as in Example 1 was made into a bag and boiled in the same manner as in Example 6, no change in appearance such as delamination or whitening was observed, and good boil resistance was exhibited. Was. The film did not yellow even when exposed to a fluorescent lamp for 1 month.

[0067]

[Table 1]

[0068]

[Table 2]

[0069]

[Table 3]

[0070]

[Table 4]

[0071]

As described above, according to the present invention, a multilayer film that does not contain bubbles such as voids even when it is extruded at high temperature and at high speed and that has a good adhesive force between EVOH and an adhesive resin. And can be suitably applied to various foods, pharmaceuticals, industrial chemicals, cosmetics and the like.

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 47/00-47/96 B32B 27/00-27/42

Claims (8)

(57) [Claims] 1. A characteristic value (P value) representing a thermal decomposition behavior is 4
Multilayer structure characterized by coextrusion coating of an ethylene-vinyl ester copolymer saponified product (A) for 5 seconds or more and 15 minutes or less and an adhesive polyolefin resin (B) on a substrate (C). Body manufacturing method. P value ... Inner diameter 2 mm
A melt indexer having a φ, 1 cm long nozzle and a cylinder with an inner diameter of 9.5 mmφ was heated to 300 ° C., 5 g of the sample resin was put into the cylinder, and immediately 2.1.
After applying a load of 6 kg and discharging 1 g of the sample resin from the nozzle, the load is removed, the nozzle is closed, and then 480
Start timing with a load of g. When the piston moves up by 5 mm, the timing is stopped and the time between them is defined as the P value. 2. A characteristic value (P value) representing the thermal decomposition behavior is 1
The method for producing a multilayer structure according to claim 1, which is not less than 10 minutes and not more than 10 minutes. 3. Ethylene-vinyl ester copolymer soap
Compound (A) contains 70 to 2000 ppm of acid radical,
One (i) alkali metal ions 15~400ppm and A
Containing 10 to 300 ppm of alkaline earth metal ions, (ii) containing 100 ppm or more of alkali metal ions
Or (iii) contains 50 ppm or more of alkaline earth metal ion
Having, satisfying either of the multilayer structure according to claim 1 or 2, wherein
Manufacturing method of structure. 4. The base material (C) has a resin layer provided with adhesiveness on at least one side, and the adhesive resin surface of the adhesive polyolefin resin (B) layer and the base material (C) is provided. 4. Any of claims 1 to 3 , which are laminated so as to be adjacent to each other.
2. A method for producing a multilayer structure according to item 1 . 5. The method for producing a multilayer structure according to claim 1 , wherein a sealant is laminated on at least one surface of the multilayer structure. 6. The characteristic value (P value) representing the thermal decomposition behavior is 4
A substrate having an ethylene-vinyl ester copolymer saponified product (A) layer for 5 seconds or more and 15 minutes or less, an adhesive polyolefin resin (B) layer, and a resin layer provided with adhesiveness on at least one surface ( C), and the layer structure is (A)
/ (B) / (C), wherein the adhesive polyolefin resin (B) layer and the base material (C) are provided with a resin layer surface provided with adhesiveness, which is adjacent to each other. P value ... Inner diameter 2 mmφ, length 1 cm nozzle and inner diameter 9.5 mm
Melt indexer with φ cylinder at 300 ℃
Then, 5 g of the sample resin was put in the cylinder, and immediately after applying a load of 2.16 kg to discharge 1 g of the sample resin from the nozzle, the load was removed, the nozzle was sealed, and then a load of 480 g was applied. Start timing. 5 pistons
Stop the time when mm rises, P
The value. 7. An ethylene-vinyl ester copolymer soap.
Compound (A) contains 70 to 2000 ppm of acid radical,
One (i) alkali metal ions 15~400ppm and A
Containing 10 to 300 ppm of alkaline earth metal ions, (ii) containing 100 ppm or more of alkali metal ions
Or (iii) contains 50 ppm or more of alkaline earth metal ion
Having, satisfying either of the multilayer structure according to claim 6, wherein. 8. A sealant is laminated adjacent to the saponified ethylene-vinyl ester copolymer (A) layer,
The multilayer structure according to claim 6 or 7 .