JP3032615B2 - Multilayer structure and package - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer structure having improved heat sealing while maintaining gas barrier properties and non-adsorption of contents.

[0002]

2. Description of the Related Art Saponified ethylene-vinyl ester copolymers (hereinafter abbreviated as EVOH) have been widely used because of their excellent gas barrier properties, but they have been used as an intermediate layer or outermost layer of packaging materials. In many cases. The main reason is that when using EVOH as the innermost layer, the heat sealing temperature is not as low as that of low density polyethylene, etc., and it lacks high-speed bag-making properties, or the outer layer film deteriorates its appearance due to thermal deformation, which significantly deteriorates the product image. In other words, the heat sealing strength was not as large as low density polyethylene . Therefore, a film such as biaxially stretched polypropylene, biaxially stretched nylon, biaxially stretched polyethylene terephthalate, or biaxially stretched EVOH is used as the outermost layer, and a film such as biaxially or unstretched EVOH is used as the intermediate layer. As the inner layer, a film such as low-density polyethylene, ethylene-vinyl acetate copolymer, ionomer, linear low-density polyethylene, or unstretched polypropylene was often used. Depending on the application, the above multilayer film is used as a lid material, and the outermost layer is a film or sheet such as unstretched polypropylene, unstretched nylon, unstretched polyvinyl chloride, unstretched polyethylene terephthalate, or unstretched polystyrene, and the middle layer is unstretched Film such as EVOH, and for the innermost layer, low-density polyethylene, ethylene-vinyl acetate copolymer, linear low-density polyethylene, ionomer, unstretched polyvinyl chloride, unstretched polystyrene, unstretched polyethylene terephthalate, or unstretched A multilayer packaging material has been adopted in which a film or sheet of polypropylene or the like is compounded and a deep-drawn container is used as a bottom material. However, such multi-layer packaging materials have high gas barrier properties as compared with those of other materials, but are expensive, and have a drawback that they are difficult to use as inexpensive general packaging materials. In addition, since the innermost layer is made of polyolefin, the contents such as food,
Flavor in drinking water (such as juice) was not sufficiently adsorbed. Therefore, EVOH with good gas barrier properties
To impart heat sealing property to the inner layer so that it can be used as the innermost layer,
It is also important from the viewpoint of cost reduction of packaging materials and is highly desired.

JP-B-61-58307 discloses an innermost layer having an ethylene content of 25 to 60 mol%, a saponification degree of a vinyl acetate component of 96% or more, an EVOH layer and an outermost layer. A laminate film provided with a thermoplastic resin layer having a heat deformation temperature higher by at least 10 ° C. than an adhesion temperature at which a peel strength of 300 g / 15 mm is obtained when heat-sealed under the conditions of 5 kg / cm ² and a time of 2 seconds; It describes a packaging material in which the innermost layers are heat sealed. However, the heat sealing strength of this product is 1050 g / 15 mm at the maximum in Table 1 of the publication, which is sufficient for packaging of a light-weight product. The importance of the heat sealing strength and the required strength level can be understood from the fact that even the heat sealing strength of the sealed part is 1.0 kg or more), and when packing heavy objects, especially liquids and viscous materials. However, the above-mentioned heat sealing strength is insufficient, and improvement of the heat sealing strength has been desired.

JP-A-49-4772 discloses that EVOH (A) having an ethylene content of 10 to 70 mol% and a saponification ratio of 80 mol% or more includes an ethylene content of 72 to 98 mol% and a saponification ratio of 50 mol%. EVOH (B) or E
It is described that a blend (C) of an EVOH (B) and an olefin polymer containing 10% by weight or more of VOH (B) is laminated. However, the EVOH of this publication
Since (B) has a high ethylene content, the non-adsorption property of the contents is not sufficient. Further, the publication does not describe the relationship between the ethylene contents of the innermost layer EVOH and the EVOH of the intermediate layer adjacent thereto.

Japanese Patent Application Laid-Open No. 56-86949 discloses a differential scanning calorimeter which is a composition comprising two or more EVOHs having an ethylene content of 20 to 55 mol% and a saponification degree of a vinyl acetate component of 80 mol% or more. Are described for melt-kneaded resin compositions in which the melting curve according to the above shows virtually a single peak. However, there is a description in this publication regarding improvement in melt moldability, but no description regarding use of the innermost layer or heat sealing.

[0006] JP-A-60-144304, saponification degree 95 mol% or more of vinyl acetate component, an ethylene content of 25 to 60 mol%, the olefinic compound content containing silane 0.0005 A melt-molded material of silane-containing EVOH which is mol% is described.
However, the publication mentions that silane-containing EVOH improves stress cracking resistance, humidity dependence of gas barrier properties such as oxygen, polar solvent resistance, water resistance, etc. There is no description about the innermost layer, heat sealing between the innermost layers, and improvement in heat sealing properties and heat sealing strength.

JP-A-60-173038 discloses a plurality of EVOH copolymer compositions having a vinyl alcohol content of 40 to 80 mol% and a residual vinyl ester content of 4 mol% or less. It describes a melt-kneaded resin composition whose melting curve by a scanning calorimeter shows a plurality of endothermic peaks. However, the publication discloses improvement in gas barrier properties under high humidity conditions and use of an intermediate layer, but does not describe heat sealability.

[0008] JP-A-63-3950 discloses LDP.
A container for juice packaging of the configuration E-board-LDPE-EVOH-tie layer-EVOH is described. However, in the publication, between EVOH and EVOH,
There is a polyolefin binding layer, which adsorbs the contents, so that the expected effect cannot be obtained.

JP-A-63-230575 discloses that the ethylene content is 20 to 60 mol% and the saponification degree is 96 mol% or less.
Two EVOs of the above EVOH and EVOH having an ethylene content of 24-49 mol% and a degree of saponification of less than 96 mol%
H are described. However, although there is a description in the gazette regarding improvement of heat high-speed stretchability,
There is no description about the use of the innermost layer or heat sealing.

Japanese Patent Application Laid-Open No. 63-264656 discloses a composition comprising two types of EVOH having an ethylene content of 45 to 60 mol% and a saponification degree of a vinyl acetate component of 96 mol% or more. Describes a resin composition whose melting curve by differential scanning calorimetry shows a plurality of endothermic peaks. However, this publication also describes improvement in high-speed stretchability under heating, but does not describe use of the innermost layer or heat sealability.

JP-A-3-24952 discloses a silane content of 0.0005 to 0.2 obtained by saponifying a copolymer of ethylene, vinyl acetate and a vinylsilane compound.
Mol%, a saponification degree of the vinyl acetate component of 96 mol% or more, and an ethylene-vinyl acetate copolymer saponified layer having an ethylene content of 25 to 60 mol% as an innermost layer, and the innermost layers are heat-sealed to form a multilayer package. The body is described. However, the publication does not describe the relationship between the ethylene content of both the innermost layer EVOH and the EVOH of the intermediate layer adjacent thereto.

Japanese Patent Application Laid-Open No. 55-12108 discloses that surging of a discharge body is prevented by melt-molding EVOH containing boron. In addition, Japanese Unexamined Patent Publication No.
No. 192564, an EVOH layer containing boron and a polyolefin layer are laminated via an adhesive layer made of a modified polyolefin having a carboxyl group or a hydroxyl group,
Although it is described that the interlayer adhesion is improved, there is no description in these publications of laminating an EVOH layer containing boron and an EVOH layer having a different ethylene content from the EVOH layer.

[0013]

As described above, development of EVOH having good gas barrier properties and improved heat sealing at low temperatures is one of the important issues in the packaging industry. but while maintaining the non-adsorbing high gas barrier properties and content, improved heat sealing properties, not obtained multilayer packaging material having sufficient heat sealing strength.

[0014]

The inventor of the present invention has conducted intensive studies based on the recognition of the problems of the prior art as described above. As a result, the ethylene content is 10 to 50 mol% and the degree of saponification of the vinyl ester component is high. 95% by mole or more of a saponified ethylene-vinyl ester copolymer (A) layer, an ethylene content of 30 to 70% by mole adjacent to the layer, a saponification degree of the vinyl ester component of 90% by mole or more, and a boron compound containing boron. A multilayer structure comprising a saponified ethylene-vinyl ester copolymer (B) layer containing 0.002 to 0.6% by weight in terms of a reduced amount and satisfying the following formula, has a gas barrier property and a non-adsorption property of the content. It has been found that the heat sealing property can be improved while maintaining the above, and the present invention has been completed. 3 ≦ EB−EA ≦ 60 wherein EA and EB represent the respective ethylene contents (mol%) of (A) and (B).

Hereinafter, the present invention will be described in more detail. In the present invention, EVOH is a polymerization of ethylene and vinyl ester by a known method using a polymerization initiator such as benzoyl peroxide or azobisisobutyronitrile in a solvent such as methanol or t-butyl alcohol under pressure. And then saponified with an alkali catalyst or an acid catalyst to obtain a saponified ethylene-vinyl ester copolymer. As vinyl esters, vinyl acetate, vinyl propionate,
Various vinyl esters such as vinyl versatate and vinyl pivalate may be mentioned, but vinyl acetate is preferred from the viewpoint of price and the like, and vinyl pivalate is preferred from the viewpoint of gas barrier properties. One or more of these vinyl esters are used. Boron may be added as boric acid in any of the polymerization step, saponification step, purification step and drying step, or boric acid may be added in the form of an ester or a metal salt such as sodium or potassium.

In the present invention, the ethylene content of EVOH (A) is 10 to 50 mol%, preferably 20 to 45 mol%, and the degree of saponification of the vinyl ester component is 95 mol% or more, preferably 97 mol% or more. . If the ethylene content is less than 10 mol%, the gas barrier properties at high humidity will decrease and the heat melting stability will deteriorate. On the other hand, if it exceeds 50 mol%, sufficient gas barrier properties cannot be obtained. On the other hand, when the degree of saponification is less than 95 mol%, not only does the gas barrier property at high humidity deteriorate, but also the thermal stability of EVOH deteriorates, and gel is likely to be generated on the obtained film surface.

In the present invention, the ethylene content of EVOH (B) is 30 to 70 mol%, preferably 40 to 65 mol%, and the degree of saponification of the vinyl ester component is 90 mol% or more, preferably 95 mol% or more. . If the ethylene content is less than 30 mol%, the low-temperature heat sealability is poor.
If the amount exceeds 0 mol%, the non-adsorption property is deteriorated. Also, when the saponification degree is less than 90 mol%, not only the non-adsorption property is deteriorated, but also the thermal stability of EVOH is deteriorated, and a gel is easily generated on the obtained film surface.

In the present invention, the value obtained by subtracting the ethylene content (mol%) EA of EVOH (A) from the ethylene content (mol%) EB of EVOH (B) is 3 or more, and is 60 or more.
Or less, preferably 10 or more. If the difference is less than 3, both the gas barrier properties and the heat sealing strength are not balanced, and if it exceeds 60, the EVOH (B)
And the adhesive strength between EVOH and EVOH (A) is reduced, and the heat sealing strength is still insufficient.

In the present invention, when the EVOH (A) layer (the (A) layer is a blend (a blend with a different type of EVOH, another thermoplastic resin, an inorganic substance, etc.)), the melt flow rate ( Weight to be discharged in 10 minutes at a temperature of 210 ° C. and a load of 2.16 kg according to JIS K 7210) MFRA is 0.1 or more, preferably 2
As described above, the melt flow rate MFR of the EVOH (B) layer {if the (B) layer is a blend, the blend layer}
Desirably smaller than B. If the MFRA is less than 0.1, a gel due to heat insolubility may easily be generated on the obtained film surface. When MFRA is larger than MFRB, EVOH (A) flows depending on the heat sealing conditions,
(A) The layer may be so thin that sufficient heat sealing strength may not be obtained. MFRB is more than 0.1 and 50 or less, preferably 2 or more and 25 or less. When the MFRB is 0.1 or less, a gel due to heat insolubility is likely to be generated on the obtained film surface. On the other hand, if the MFRB exceeds 50, the melt viscosity decreases, and it may be difficult to form a multilayer body having a good appearance.

In the present invention, the difference between the melting point MPA of EVOH (A) and the melting point MPB of EVOH (B) measured at a heating rate of 10 ° C./min using a DSC at 5 ° C.
Above, preferably 8 ° C. or higher. If the difference in melting points is less than 5 ° C., the heat sealing strength of the entire multilayer structure will not be sufficient.

In the present invention, the thickness of one layer of the EVOH (B) is 6 μm or more, and the EVOH (A) layer
The total thickness of the (B) layer is desirably 10 μm or more and 200 μm or less, preferably 20 μm or more and 80 μm or less. If the total thickness is less than 10 μm, it is difficult to obtain a sufficient heat sealing strength. If the total thickness exceeds 200 μm, not only the cost is increased but also pinholes may be easily generated due to the bending of the packaging material. Further, in order to prevent curling of the multilayer film, (B) layer- (A) layer- (B) layer and (B) layer-
(A) layer-(B) layer-(A) layer or (B) layer-(A) layer-
A configuration of (B) layer- (A) layer- (B) layer may be adopted.

Further, the layer (A) and / or the layer (B)
Each may be a single layer or a multilayer. In the case of a multilayer, the same type of EVOH can be used for each layer, or different types of EVOH (EVO having different melting points) can be used.
H etc.) can also be used. It is best to provide the layer (A) and the layer (B) adjacent to each other, but if necessary, the layer (A) and the layer (B) may be provided between the layer (A) and the layer (B) as long as the object of the present invention is not hindered. Layers may intervene. (A)
The layer and the layer (B) are obtained by a co-extrusion method, a dry lamination method, an extrusion coating method, or the like.
The layers and (B) layers may be oriented by stretching (uniaxial or biaxial).

The boron equivalent of the boron compound contained in the EVOH (B) is 0.002 to 0.6% by weight, preferably 0.009 to 0.35% by weight. If the boron content is less than 0.002% by weight, the heat sealing property and the heat sealing strength at low temperatures are not sufficiently improved, while the content is 0.6% by weight.
When the ratio exceeds the above, the degree of crosslinking is excessively increased and heat insolubility is exhibited. As the boron compound, boric acid is the best, but trichloroboron, triphenylboron, trimethylboron, or a coordination product of these with an ether or an amine, or a compound in which boron is converted into a quantifier through a bond of oxygen and nitrogen is also used. it can.

In the EVOH (A) and / or (B), a smaller amount of propylene, butene-1, isobutene, 4-
Α-olefins such as methylpentene-1, hexene-1 and octene-1, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, salts thereof, partial or complete esters thereof, nitriles thereof and amides thereof , Anhydrides, alkylthiols, unsaturated sulfonic acids, and salts thereof.

An acid, a base and salts thereof may be added to the EVOH (A) and / or (B) as long as the present invention is not impaired. Acids, bases and salts thereof include acetic acid, phosphoric acid, sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium acetate, calcium acetate, potassium phosphate, calcium phosphate,
Examples thereof include calcium hydrogen phosphate, dipotassium monohydrogen phosphate, and monopotassium dihydrogen phosphate. Further, silicon oxide, aluminum oxide or the like may be added to improve the slipperiness of the molded product. In addition, various additives such as antioxidants, coloring agents, ultraviolet absorbers, antistatic agents, plasticizers, crosslinking agents, inorganic fillers, inorganic desiccants, and various resins such as polyamides, polyolefins, and superabsorbent resins are blended. You may.

The EVOH (A) and / or (B) may be composed of a mixture of two or more types of EVOH having different ethylene copolymerization ratios, or two types having different degrees of polymerization and saponification. A mixture of the above EVOHs may be used. Further, the ethylene copolymerization ratio, the degree of polymerization and the degree of saponification may be different from each other, but it is important that their average values fall within the above-mentioned EVOH ranges. Furthermore, the EVOH (A) and / or the EVOH (B) may be different from each other in the heat-sealed multilayer structure as described in Example 4 below.

In the present invention, the multilayer structure may be used as it is as a packaging material, but in the case of a film, it is difficult to obtain a sufficient heat seal strength. The outer layer of the (A) layer, especially the thermoplastic resin (C) layer whose Vicat softening point measured by the method specified in JIS K 7206 is higher than EVOH (B) by 5 ° C or more, preferably 10 ° C or more. However, it is possible to obtain a packaging material having not only a sufficient heat sealing strength but also a good heat sealing property. When the difference in the Vicat softening point is less than 5 ° C., the heat resistance of the outermost layer during heat sealing is not sufficient, and poor appearance such as wrinkles and edge breakage due to insufficient heat resistance are likely to occur.

Next, in the present invention, a method for producing a multilayer structure having EVOH (B) as the innermost layer, in particular, a multilayer structure having another layer in the multilayer structure comprising the EVOH (A) layer and the (B) layer is described as follows. EVOH (A) surface of multilayer structure including EVOH (A) layer and (B) layer {(B) layer—
(A) layer-When the (A) surface is not exposed as in the (B) layer, the same applies to the following (1) and the thermoplastic resin (C) film so that one (B) layer comes to the innermost layer. Or, a method of dry laminating an aluminum foil and a method of polysand laminating an EVOH (A) surface of a multilayer structure comprising an EVOH (A) layer and a (B) layer and another film (C) or an aluminum foil or paper. (Method of laminating with anchor coat agent via polyethylene in a molten state), method of dry or wet laminating paper with EVOH (A) surface of multilayer structure comprising EVOH (A) layer and (B) layer, film Coextrusion coating of (C) or paper or aluminum foil so that the EVOH (A) surface of the multilayer melt comprising the EVOH (A) layer and (B) layer is in contact (Anchoring agent may be interposed), the EVOH (A) surface of the multilayer melt comprising the EVOH (A) layer and the (B) layer is adjacent to an adhesive (for example, a carboxylic acid graft-modified polyolefin resin), and Alternatively, a method of coextrusion coating so that the adhesive surface is in contact with the film (C) or the aluminum foil (may be through an anchor coat agent), an EVOH of a multilayer melt composed of an EVOH (A) layer and a (B) layer ( A) A method of co-extruding and laminating the surface so as to be adjacent to the melt of the thermoplastic resin (C) (an adhesive such as a carboxylic acid graft-modified polyolefin resin may be used). The multilayer structure (film, sheet, bottle, tube, or the like) thus obtained is subjected to EVOH (B)
A multilayer package such as a pouch or a tray can be obtained by heat sealing so that the layer becomes the innermost layer. Further, the multilayer body obtained above is used as a lid material, and the multilayer structure obtained separately is deep-drawn and formed as a bottom material, and heat-sealed so that the EVOH layer becomes the innermost layer to form a multilayer packaging body. Is also good. Further, the multilayer structure obtained as described above may be heat-sealed so that the EVOH (B) layer is the innermost layer to form a body of a two-piece tube, and a multilayer package may be formed using the body. Furthermore, the multilayer structure obtained as described above is used as a lid material, and the EVOH (B) layers are heat-sealed to the mouth of a direct or injection blow bottle or one-piece tube having the EVOH (B) layer as the innermost layer. To form a multilayer package.

Examples of the film of the thermoplastic resin (C) include the following. Biaxially stretched film mainly composed of propylene homopolymer. A biaxially stretched film mainly composed of nylon obtained mainly from a homopolymer of ε-caprolactam, a diamine component such as hexamethylenediamine or meta-xylylenediamine, and adipic acid. A biaxially stretched polyester film obtained using ethylene glycol and terephthalic acid or naphthalene dicarboxylic acid as main raw materials. A film made of polycarbonate obtained using bisphenol-A and a carbonate derivative such as phosgene as main raw materials. A film made of polyvinyl chloride whose main material is vinyl chloride and copolymerized with vinyl acetate.
A biaxially stretched film made of polyvinylidene chloride obtained by copolymerizing vinyl chloride, acrylonitrile, (meth) acrylate, and the like with vinylidene chloride as a main raw material. A biaxially stretched polystyrene film obtained by copolymerizing butadiene, acrylonitrile, and the like with styrene homopolymer and styrene as main raw materials. Rolled or biaxially stretched high-density polyethylene films and the like can be mentioned.

Further, as the thermoplastic resin (C) at the time of the above-mentioned co-extrusion lamination, the following may be mentioned. Diamine components such as hexamethylenediamine, piperazine, tetramethylenediamine, ethylenediamine, and meta-xylylenediamine; and amino acids such as δ-valerolactam, ε-caprolactam, ω-laurolactam, ω-aminoundecanoic acid, and ω-aminododecanoic acid A nylon obtained from a carboxylic acid component and a polyvalent carboxylic acid component such as naphthalenedicarboxylic acid, terephthalic acid, isophthalic acid, azelaic acid, sebacic acid, pimelic acid, adipic acid, glutaric acid, and succinic acid as raw materials. Ethylene glycol, diethylene glycol, trimethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 4,4'-dihydroxydiphenyl-
Polyhydric alcohol components such as 2,2-propane, glycerin and pentaerythritol, and hydroxycarboxylic acid components such as parahydroxybenzoic acid, δ-valerolactone and ε-caprolactone, terephthalic acid, isophthalic acid, various naphthalenedicarboxylic acids, Azelaic acid,
Polyester obtained from polycarboxylic acids such as sebacic acid, pimelic acid, adipic acid, glutaric acid and succinic acid and their ester components as raw materials. Bisphenol-A
And a polycarbonate obtained using a carbonic acid derivative such as phosgene as a main raw material. Homopolymers of propylene, and block and random copolymers of propylene as a main component with ethylene, butene-1, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, hexa-1,4-diene, etc. And their graft-modified products which are graft-modified with carboxylic acids such as maleic anhydride. High-density polyethylene, medium-density polyethylene, low-density polyethylene, which are homopolymers of ethylene, and propylene, butene-1, buta-1,3-diene, and 4-methylpentene containing ethylene as a main component
1, hexene-1, octene-1, norbornene, 5-
Copolymers with methylene-2-norbornene, 5-ethylidene-2-norbornene, vinyl acetate, butyl acetate, methyl acrylate, ethyl acrylate, acrylic acid, methyl methacrylate, ethyl methacrylate, methacrylic acid, The copolymer with acrylic acid or methacrylic acid may be cross-linked with sodium, zinc, aluminum or the like. Further, in the copolymer with vinyl acetate, a part or all of the vinyl acetate component may be saponified. Further, polyethylene may be graft-modified with a carboxylic acid such as maleic acid, maleic anhydride, itaconic acid, and itaconic anhydride. Polyvinyl chloride obtained by copolymerizing vinyl acetate with vinyl chloride as the main raw material. Polyvinylidene chloride obtained by copolymerizing vinyl chloride, acrylonitrile, (meth) acrylate, etc., with vinylidene chloride as the main raw material. Polystyrene made from styrene homopolymer and styrene as main raw materials and copolymerized with (meth) acrylate, butadiene, acrylonitrile and the like. It is a so-called graft copolymer composed of a copolymer of styrene with acrylonitrile as a main component, and a copolymer of methacrylic acid with acrylonitrile as a main component and butadiene. Certain polyacrylonitrile and the like can be mentioned.

The EVOH thus obtained according to the present invention
Containers (bags, cups, tubes, etc.) composed of a multilayer structure (film or sheet, etc.) having (B) as the innermost layer
Filling the contents (food, drinking water, cosmetics, etc.) into a bottle, etc., and heat-sealing the (B) layers together to obtain a multilayer package having improved heat-sealing properties and heat-sealing strength. be able to. The multilayer package obtained in this way is useful as a package for foods in which flavor such as juice is important, and pharmaceuticals such as cataplasms containing volatile medicinal ingredients, fragrances, and soaps. It is also useful as a package for a remover, an insect repellent, an industrial chemical, a medical device requiring gas barrier properties or chemical resistance.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0033]

【Example】

Example 1 EVOH (A) obtained by saponifying a copolymer of ethylene and vinyl acetate, an ethylene content of 32 mol%, a saponification degree of a vinyl acetate component of 99.5 mol%, and a melt flow rate of 3.3 g / 10 Minute (210 ° C., 2.16 kg load) 10 μm of EVOH, ethylene as EVOH (B),
A boron acetate copolymer obtained by saponifying a vinyl acetate copolymer has a boron equivalent content of 0.02% by weight, an ethylene content of 48 mol%, a saponification degree of a vinyl acetate component of 99.5 mol%, and a melt flow rate of 18 g / 10 minutes ( E of 210 ° C, 2.16 kg load)
A coextruded film having a VOH (Vicat softening point of 148 ° C.) of 15 μm was obtained.

15 μm biaxially stretched nylon film (“Bonille R” manufactured by Kojin Co., Ltd., Vicat softening point 17)
(0 ° C.)), a polyester-based adhesive (“A-385 / A-50” manufactured by Takeda Pharmaceutical Co., Ltd.) as a solid content of 3 g / m ^{2 was} applied to the corona-treated surface, and the solvent was evaporated. The EVOH (A) side of the co-extruded film was bonded to obtain a composite film.

Using a heat sealer, the EVOH (B) faces were heat-sealed with a heat sealer at a pressure of 0.5 kg / cm ² , a temperature of 130 ° C. and a time of 2 seconds to obtain a multilayer package.
When the heat sealing strength was measured, it was as strong as 2.2 kg / 15 mm, and the appearance was good without shrinkage. In addition, oxygen gas permeation amount (“OX” manufactured by Modern Controls)
-TRAN 10 / 50A) at 20 ° C, 85%
(Relative humidity) was as excellent as ² ml / m ² · day · atmospheric pressure.

10 ml of limonene was placed in a 30-ml test tube, covered with a cover so that the side (B) of the multilayer-constituent film was on the inside, and allowed to stand at 20 ° C. and 65% (relative humidity) for one week. 2 mg of the packaging material was cut out and heated at 120 ° C. for 10 minutes in a helium atmosphere in a quartz tube to desorb adsorbed d-limonene. The volatilized d-limonene was heated from 40 ° C. to 170 ° C. by PEG-20M-bonded capillary chromatography (inner diameter 0.25 mm, length 50 m) using helium as a carrier gas, and the amount of adsorption was determined from the obtained peak area. Was quantified. The amount of adsorbed d-limonene is
It was as good as 20 μg / g of film.

COMPARATIVE EXAMPLE 1 In Example 1, the copolymer of ethylene and vinyl acetate was saponified as EVOH (B), and the ethylene content was 48 mol%, the saponification degree of the vinyl acetate component was 99.5 mol%, A similar composite film was obtained in the same manner as in Example 1 except that the melt flow rate was 48 g / 10 min and the EVOH (Vicat softening point: 148 ° C.) was 15 μm.

Using a heat sealer, the EVOH (B) surfaces were heat-sealed with a heat sealer at a pressure of 0.5 kg / cm ² , a temperature of 130 ° C. and a time of 2 seconds to obtain a multilayer package.
The heat sealing strength was only 0.5 kg / 15 mm.
Was very inferior to The oxygen gas permeation amount is 20
2 ml / m ² · day · pressure at 85 ° C (relative humidity) and 30 µg / g of film adsorbed on d-limonene
And was excellent.

Example 2 As a EVOH (A), a copolymer of ethylene and vinyl acetate was saponified to obtain an ethylene content of 43 mol%, a saponification degree of a vinyl acetate component of 99.5 mol%, and a melt flow rate of 12 g / 10 minutes EVOH to 10 μm, EVOH
As (B), a copolymer of ethylene and vinyl acetate was saponified to obtain a boron-converted content of 0.05% by weight, an ethylene content of 60% by mole, a saponification degree of the vinyl acetate component of 99.4% by mole, and a melt flow. EVOH at a rate of 24 g / 10 min
(Vicat softening point 134 ° C.) to give a co-extruded film having a thickness of 15 μm.

A 20 μm biaxially stretched polypropylene film (Tocello OP U- manufactured by Tokyo Cellophane Paper Co., Ltd.)
1), a polyester adhesive ("A-3" manufactured by Takeda Pharmaceutical Co., Ltd.) on the corona-treated surface having a Vicat softening point of 150 ° C.
85 / A-50 ") as a solid content of 3 g / m ² ,
After evaporating the solvent, the EVO of the coextruded film
The composite film was obtained by laminating the H (A) faces.

Using a heat sealer, the EVOH (B) surfaces of the laminated film were heat-sealed at a pressure of 0.5 kg / cm ² , a temperature of 130 ° C. and a time of 2 seconds to obtain a multilayer package.
The heat sealing strength was as strong as 2.1 kg / 15 mm, and the appearance was good without shrinkage. The oxygen gas permeation amount is 20
It was excellent at 5 ml / m ² · day · atmospheric pressure at 85 ° C. and 85% (relative humidity), and the amount of adsorbed d-limonene was as good as 400 μg / g of film.

Comparative Example 2 A silane content of 0.07 mol%, an ethylene content of 60 mol%, obtained by saponifying a copolymer of ethylene, vinyl acetate and vinyl trimethoxysilane as EVOH (A).
The degree of saponification of the vinyl acetate component is 99.4 mol%, the melt flow rate is 9 g / 10 min, and the EVOH is 10 μm.
As (B), a copolymer of ethylene and vinyl acetate was saponified to obtain a content in terms of boron of 0.09% by weight, an ethylene content of 70% by mole, a degree of saponification of the vinyl acetate component of 97% by mole, and a melt flow rate of 14 g. A similar composite film was obtained in the same manner as in Example 2, except that a co-extruded film having an EVOH (Vicat softening point of 120 ° C.) of 15 μm was obtained for / 10 minutes.

Using a heat sealer, the laminated film was heat-sealed between the EVOH (B) surfaces at a pressure of 0.5 kg / cm ² , a temperature of 130 ° C. and a time of 2 seconds to obtain a multilayer package.
When the heat sealing strength was measured, it was as excellent as 2.6 kg / 15 mm. However, the oxygen gas permeation amount of this laminated film was 35 ml / m 2 at 20 ° C. and 85% (relative humidity).
^2. Day and pressure were inferior to Example 1. Further, the adsorbed amount of d-limonene was 1800 μg / g of film.

Example 3 As an EVOH (A), a copolymer of ethylene and vinyl acetate was saponified to obtain an ethylene content of 27 mol%, a saponification degree of a vinyl acetate component of 99.5 mol%, and a melt flow rate of 3. 3 μm / 10 minute EVOH to 10 μm, EVOH
As (B), a copolymer of ethylene and vinyl acetate was saponified to obtain a content of 0.02% by weight in terms of boron, an ethylene content of 45% by mole, a saponification degree of a vinyl acetate component of 99.5% by mole, and a melt flow. EVOH at a rate of 17 g / 10 min
(Vicat softening point: 155 ° C.) to give a coextruded film having a thickness of 20 μm.

A 25 μm biaxially stretched polyethylene terephthalate film (“Lumirror P-1” manufactured by Toray Industries, Inc.)
1 ", Vicat softening point 190 ° C) and polyester adhesive (" A-385 / A-5 "manufactured by Takeda Pharmaceutical Co., Ltd.)
0 ") as a solid content was applied at 3 g / m ² , the solvent was evaporated, and the EVOH (A) face of the co-extruded film was laminated to obtain a composite film.

Using a heat sealer, the EVOH (B) surfaces of the laminated film were heat-sealed at a pressure of 0.5 kg / cm ² , a temperature of 160 ° C. and a time of 2 seconds to obtain a multilayer package.
When the heat sealing strength was measured, it was as strong as 2.9 kg / 15 mm, and the appearance was good without shrinkage. The oxygen gas permeation amount is 1 ml at 20 ° C and 85% (relative humidity).
/ M ² · day · atmospheric pressure, and the adsorbed amount of d-limonene was also good at 50 μg / g of film.

Comparative Example 3 EVOH (A) obtained by saponifying a copolymer of ethylene and vinyl acetate, having an ethylene content of 47 mol%, a saponification degree of the vinyl acetate component of 99.5 mol%, and a melt flow rate of 36 g / 20 minutes EVOH for 10 minutes, EVOH
As (B), a copolymer of ethylene and vinyl acetate was saponified to obtain a content in terms of boron of 0.01% by weight, an ethylene content of 31% by mole, a saponification degree of the vinyl acetate component of 99.5% by mole, and a melt flow. EVOH at a rate of 1.3 g / 10 min
A similar composite film was obtained in the same manner as in Example 3 except that a coextruded film having a (Vicat softening point of 173 ° C.) of 10 μm was obtained.

Using a heat sealer, the EVOH (B) surfaces were heat-sealed with a heat sealer at a pressure of 0.5 kg / cm ² , a temperature of 160 ° C. and a time of 2 seconds to obtain a multilayer package.
Although there was no shrinkage in the seal portion and the appearance was good, the heat sealing strength was measured and found to be only 0.4 kg / 15 mm.
The heat sealing strength was very inferior to Example 3. The oxygen gas permeation amount of this laminated film was 20 ° C., 85%
(Relative humidity) is 2 ml / m ² · day · atmosphere,
The amount of adsorbed d-limonene was also good at 170 μg / g of film.

Example 4 One of the multilayer components was obtained by saponifying a copolymer of ethylene and vinyl acetate as EVOH (A). The ethylene content was 27 mol%, and the degree of saponification of the vinyl acetate component was 99.5.
Mol%, melt flow rate 3.3g / 10min EVO
H is 20 μm, and EVOH (B) is saponified from a copolymer of ethylene and vinyl acetate.
EVOH obtained by saponifying a copolymer of 0.5% by weight, an ethylene content of 48% by mole, a saponification degree of a vinyl acetate component of 99.5% by mole, and a melt flow rate of 14g / 10min.
(Vicat softening point: 148 ° C.) is 20 μm, and as another multilayer structure, EVOH (A) is obtained by saponifying ethylene and vinyl acetate copolymer. EVOH with a saponification degree of 99.5 mol% and a melt flow rate of 3.3 g / 10 min
Is 20 μm, and the EVOH (B) is saponified from a copolymer of ethylene and vinyl acetate.
2 wt%, ethylene content 45 mol%, saponification degree of vinyl acetate component 99.5 mol%, melt flow rate 15 g
EVOH (Vicat softening point 155 ° C)
A similar composite film was obtained in the same manner as in Example 1 except that μm was used.

Using a heat sealer, this laminated film was heat-sealed between the EVOH (B) surfaces at a pressure of 0.5 kg / cm ² , a temperature of 160 ° C. and a time of 2 seconds. The heat sealing strength was as high as 3.4 kg / 15 mm, and the appearance was good without shrinkage. The oxygen gas permeation amount is 20 ° C and 85%
(Relative humidity), both were excellent at 1 ml / m ² · day · atmosphere, and the d-limonene adsorption amount was 6
It was as good as 0 μg / g of film.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

As described above, the multilayer structure of the present invention has good gas barrier properties and good non-adsorption of the contents, excellent heat sealing properties, juices, cataplasms, fragrances, soaps,
It can be suitably applied to packages such as insect repellents and industrial chemicals.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 B65D 65/40

Claims (3)

(57) [Claims] 1. An ethylene copolymer having an ethylene content of 10 to 50 mol% and a saponification degree of the vinyl ester component of 95 mol% or more.
A saponified vinyl ester copolymer (A) layer and an adjoining layer having an ethylene content of 30 to 70 mol%, a saponification degree of the vinyl ester component of 90 mol% or more, and a boron compound in an amount of 0.002 in terms of boron. Ethylene containing up to 0.6% by weight
A multilayer structure comprising a saponified vinyl ester copolymer (B) layer and satisfying the following formula: 3 ≦ EB−EA ≦ 60 In the formula, EA and EB represent the respective ethylene contents (mol%) of (A) and (B). 2. The multilayer structure according to claim 1, wherein a thermoplastic resin (C) layer having a Vicat softening point higher than the Vicat softening point of (B) by 5 ° C. or more is laminated on the outer layer of the (A) layer. . 3. A multilayer package comprising the multilayer structure according to claim 1 or 2, wherein contents are filled in a container having the layer (B) as an inner layer, and the layers (B) are heat-sealed.