JP2001347564A - Stretched film with excellent gas barrier properties and light blocking properties - Google Patents

Abstract

(57) [Problem] To provide a stretched film having excellent functions of shielding visible light and ultraviolet light, gas barrier properties and bending resistance. SOLUTION: An inorganic filler (B) 5 having a barrier resin (A) of 70 to 95% by weight and a particle diameter of 0.5 to 2.5 μm.
A stretched film comprising at least 30% by weight and stretched at least twice in a uniaxial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretched film excellent in a function of shielding visible light and ultraviolet light, gas barrier properties and bending resistance.

[0002]

2. Description of the Related Art Various types of containers are filled in a packaging container having a single-layer or multi-layer structure. However, the contents must be easily deteriorated by light, such as some chemicals and foods. There are many. In order to stably store such contents for a long period of time, a single-layer or multilayer structure having excellent gas barrier properties and excellent light blocking properties is required. In particular, the content of alcoholic beverages (especially sake and wine with a low alcohol content) and some chemicals can be degraded by visible light, so they have excellent light shielding in both ultraviolet and visible light. Desirable.

[0003] Conventionally, as a multilayer container containing a layer composed of a resin composition in which an inorganic filler is added to an ethylene-vinyl alcohol copolymer, Japanese Patent Application Laid-Open No. 5-193076 discloses an ethylene content of 20 to 60 mol% and a saponification degree of 95. Mol% or more of ethylene-vinyl alcohol copolymer 50 to 95
A multilayer container is disclosed in which a resin composition (A) composed of 50% by weight and 50 to 5% by weight of an inorganic filler is used as an intermediate layer, and the inner and outer layers of the intermediate layer have a moisture-resistant thermoplastic resin (B).
However, an object of the present invention is to obtain a package excellent in thermoformability and gas barrier properties during retort,
No light blocking property is described. In addition, although there is a description about the stretchability when producing a thermoformed container, as in the stretched film of the present invention, in order to obtain an extremely high gas barrier property and excellent light blocking properties, the resin composition (A ) Is not described at all about stretching the layer consisting of at least two times in the uniaxial direction.

Japanese Patent Application Laid-Open No. 5-140345 discloses an ethylene-vinyl alcohol copolymer having a content of 50 to 99% by weight.
And a functional film comprising a resin composition layer composed of 1 to 50% by weight of an inorganic filler and having a surface glossiness of at least one side of 60% or less is disclosed, but a statement that the functional film is stretched. No sufficient light blocking property and gas barrier property can be obtained with a film having such a configuration (see Comparative Example 3 in the present specification).

Japanese Patent Application Laid-Open No. 11-227118 discloses at least two layers, a layer containing EVOH containing 0.05 to 0.5% by weight of talc and a layer made of polyamide. A stretched stretched film is described. However, the content of the inorganic filler (B) is clearly different between the invention described in the publication and the invention of the present application.

[0006] Further, a method of increasing the heat insulating effect by evacuating the inside of a structure sealed with a container or an outer wrapping material formed of a gas barrier material has been conventionally known. A vacuum heat insulating material in which a core material is filled in the inside of the structure and evacuated is also known. In such a vacuum heat insulating material, the gas heat transfer is reduced by maintaining the inside at a high degree of vacuum to improve the heat insulating property.In order to maintain the heat insulating property for a long time, for example, the above-described structure is used. It is necessary to use a material having extremely excellent gas barrier properties for the body.

As such a material, it is preferable to use a resin, particularly a thermoplastic resin, from the viewpoint of moldability, but polyvinylidene chloride (PVDC) or ethylene-vinyl alcohol copolymer (a typical example of a resin having excellent gas barrier properties) is used. In some cases, the gas barrier property is insufficient as a vacuum heat insulating material, and it has been difficult to maintain the heat insulating property of the obtained structure for a long period of time. Therefore, for the purpose of improving the gas barrier properties of the resin, for example, JP-A-63-279083 and JP-A-63-233284 describe a metal laminate in which an aluminum foil is laminated on a thermoplastic resin film. .

[0008] However, the vacuum heat insulating material made of the above-mentioned metal laminate can maintain a high degree of vacuum for a long period of time, but a metal such as aluminum has a large thermal conductivity (for example, aluminum has a thermal conductivity of about 200 W). / M ・
K is about 0.23W for polypropylene resin
/ M · K, about 0.02 W / m · K in air), so-called heat bridges, in which heat moves along metal parts, are likely to occur, and the heat insulation performance may be reduced.

Although it has been considered to reduce the thickness of the metal layer for the purpose of suppressing the heat bridge, in general, when laminating a metal on a thermoplastic resin layer, a metal such as aluminum is vaporized once at a high temperature to obtain a resin. In many cases, a metal foil is separately formed by vapor deposition or rolling on the surface of the layer, and then laminated on the resin layer. In these methods, if the thickness of the metal layer is reduced, sufficient flexibility and impact resistance may not always be obtained, and pinholes and the like are generated in a distribution process such as transportation, and the gas barrier is provided despite the provision of the metal layer. Properties and light blocking properties may be reduced, and long-term heat insulation performance may be reduced.

When aluminum foil is used, recycling cannot always be said to be easy. Further, at the time of incineration, there is a possibility that aluminum vapor condenses in a water pipe of a heat exchanger installed in an incinerator, thereby deteriorating thermal efficiency. was there.

[0011]

Therefore, a single-layer or multi-layer structure excellent in the function of shielding visible light and ultraviolet light, gas barrier properties and bending resistance is desired.

[0012]

SUMMARY OF THE INVENTION The above object is achieved by providing a barrier resin (A) of 70 to 95% by weight and a particle size of 0.5 to 2.5%.
It is achieved by providing a stretched film comprising 5 to 30% by weight of an inorganic filler (B) of μm and stretched at least twice in at least one axial direction.

That is, the present invention relates to a barrier resin (A) 7
The present invention relates to a stretched film comprising 0 to 95% by weight and 5 to 30% by weight of an inorganic filler (B) having a particle size of 0.5 to 2.5 μm, and stretched at least twice in at least one axial direction.

In a preferred embodiment, the barrier resin (A) used in the present invention is at least one selected from ethylene-vinyl alcohol copolymer and polymethaxylylene adipamide. An ethylene-vinyl alcohol copolymer having an amount of 5 to 60 mol% and a saponification degree of 90% or more.

In a preferred embodiment, the inorganic filler (B) used in the present invention is talc.

In a preferred embodiment, the thickness of the stretched film of the present invention is 3 to 100 μm, and the total haze is 50% or more. In a further preferred embodiment,
The difference between the total haze and the internal haze of the stretched film is 40%
It is as follows.

In a preferred embodiment, the stretched film of the present invention is used as a multilayer structure including at least one layer made of the stretched film.

In a preferred embodiment, the stretched film of the present invention is used as a multilayer structure obtained by dry laminating the stretched film on a substrate. A preferred embodiment of the multilayer structure is a paper container, and another preferred embodiment is a wallpaper or a decorative board. Further, the multilayer structure is suitably used as a vacuum heat insulating material.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Barrier resin used in the present invention
(A) is a resin having gas barrier properties. Such ba
As the rear resin (A), the oxygen permeation amount is 100 ml.
20 μm / m ^Two・ Day (measured at 20 ° C-65% RH)
Value). The upper limit of oxygen permeation is
More preferably, 10 ml · 20 μm / m^Two・ Day ・ at
m, more preferably 5 ml · 20 μm / m^Two
· Day · atm or less, particularly preferably 1 ml · 2
0 μm / m^Two· Day · atm or less.

It is also preferable to use at least one selected from the group consisting of polyvinyl alcohol resins and polyamides as the barrier resin (A) used in the present invention.

In the present invention, the polyvinyl alcohol resin refers to a resin obtained by saponifying a vinyl ester polymer or a copolymer of a vinyl ester and another monomer using an alkali catalyst or the like. As a vinyl ester, vinyl acetate is mentioned as a typical one,
Other fatty acid vinyl esters (vinyl propionate,
Vinyl pivalate) can also be used.

The degree of saponification of the vinyl ester component of the polyvinyl alcohol resin of the present invention is preferably at least 90%, more preferably at least 95%, and even more preferably at least 99%. If the saponification degree is less than 90 mol%,
There is a possibility that the gas barrier property under high humidity may decrease, and the gasoline barrier property may become insufficient. Here,
When the polyvinyl alcohol-based resin is composed of a blend of two or more types of polyvinyl alcohol-based resins having different degrees of saponification, the average calculated from the blending weight ratio is defined as the degree of saponification. The saponification degree of such a polyvinyl alcohol-based resin can be determined by a nuclear magnetic resonance (NMR) method.

As the polyvinyl alcohol-based resin of the present invention, ethylene-vinyl alcohol copolymer (from the viewpoints of being melt-moldable, having good gas barrier properties under high humidity, and having excellent gasoline barrier properties) Hereinafter, E
VOH).

The EVOH used in the present invention is preferably one obtained by saponifying an ethylene-vinyl ester copolymer.
It is preferably 0 mol%. The lower limit of the ethylene content is more preferably at least 15 mol%, even more preferably at least 25 mol%. The upper limit of the ethylene content is more preferably 55 mol% or less, and still more preferably 50 mol% or less. If the ethylene content is less than 5 mol%, the melt moldability may deteriorate, and if it exceeds 60 mol%, the barrier properties may be insufficient.

Further, the saponification degree of the vinyl ester component of EVOH used in the present invention is 90% or more. The degree of saponification of the vinyl ester component is preferably at least 95%, and most preferably at least 99%. If the saponification degree is less than 90%, gasoline barrier properties and thermal stability may be insufficient.

A typical example of the vinyl ester used in the production of EVOH is vinyl acetate.
Other fatty acid vinyl esters (vinyl propionate,
Vinyl pivalate) can also be used. Also, EVOH
Is a vinyl silane compound as a copolymer component 0.0002 to
0.2 mol% can be contained. Here, as the vinylsilane-based compound, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β
-Methoxy-ethoxy) silane and γ-methacryloxypropylmethoxysilane. Among them, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used. Further, other comonomer such as propylene, butylene, or unsaturated monomer such as (meth) acrylic acid, methyl (meth) acrylate or ethyl (meth) acrylate, as long as the object of the present invention is not hindered. A carboxylic acid or an ester thereof and vinylpyrrolidone such as N-vinylpyrrolidone can also be copolymerized.

Furthermore, a boron compound can be blended with EVOH within a range not to impair the object of the present invention.
Here, examples of the boron compound include boric acids, borate esters, borates, and borohydrides. Specifically, as boric acids, orthoboric acid, metaboric acid,
Tetraboric acid and the like, boric acid esters such as triethyl borate and trimethyl borate, and borate salts such as the above-mentioned alkali metal salts of various boric acids, alkaline earth metal salts, and borax. No. Of these compounds, orthoboric acid (hereinafter sometimes simply referred to as boric acid) is preferred.

When the boron compound is blended, the content of the boron compound is preferably 20 to 2 in terms of boron element.
000 ppm, more preferably 50 to 1000 ppm. By being in this range, it is possible to obtain EVOH in which torque fluctuation during heating and melting is suppressed. If it is less than 20 ppm, such an effect is small, and if it exceeds 2,000 ppm, gelation is likely to occur, resulting in poor moldability.

The alkali metal salt is added to the EVOH used in the present invention in an amount of 5 to 50 in terms of an alkali metal element.
It is also preferable that the content is contained at 00 ppm because it is effective for improving interlayer adhesion and compatibility. The more preferable content of the alkali metal salt is 20 to
It is 1000 ppm, furthermore 30-500 ppm.
Here, as the alkali metal, lithium, sodium,
Potassium and the like can be mentioned, and examples of the alkali metal salt include a monovalent metal aliphatic carboxylate, an aromatic carboxylate, a phosphate and a metal complex. For example, sodium acetate, potassium acetate, sodium stearate, potassium stearate, sodium salt of ethylenediaminetetraacetic acid and the like can be mentioned. Among them, sodium acetate and potassium acetate are preferred.

Further, the EVOH used in the present invention contains a phosphate compound in an amount of 20 to 500 ppm in terms of a phosphate group,
More preferably 30-300 ppm, optimally 50-20
It is also preferable to contain 0 ppm. By incorporating a phosphoric acid compound in such a range, the melt moldability and thermal stability of EVOH can be improved. In particular, by including a phosphoric acid compound in such a range, when melt molding is performed for a long time using EVOH, generation of gel-like bumps and coloring can be effectively suppressed.

[0031] The type of the phosphoric acid compound to be incorporated into the EVOH is not particularly limited. Various acids such as phosphoric acid and phosphorous acid and salts thereof can be used. The phosphate may be contained in any form of a first phosphate, a second phosphate, and a third phosphate, and the cationic species thereof is not particularly limited. And alkaline earth metal salts. Among them, it is preferable to add a phosphate compound in the form of sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate.

In addition, a heat stabilizer, an antioxidant, and a plasticizer such as glycerin or glycerin monostearate can be blended with EVOH within a range not to impair the object of the present invention.

Suitable melt flow rate (MFR) of EVOH used in the present invention (at 190 ° C. under a load of 2160 g)
Is 0.1 to 50 g / 10 minutes, more preferably 0.3 to 50 g / 10 minutes.
-40 g / 10 min, more preferably 0.5-30 g / 10 min
Minutes. However, the melting point is around 190 ° C or 190 ° C
Over 2160 g, measured at a plurality of temperatures above the melting point under a load of 2160 g.
The logarithm of FR is plotted on the vertical axis and is represented by a value extrapolated to 190 ° C. These EVOH resins can be used alone or in combination of two or more.

The polyamide used as the barrier resin (A) of the present invention is a polymer having an amide bond, for example, polycaproamide (nylon-6), polyundecaneamide (nylon-11), polylauryl. Homopolymers such as lactam (nylon-12), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene sebacamide (nylon-6,12), and caprolactam / lauryl lactam copolymer (nylon- 6 /
12), caprolactam / aminoundecanoic acid polymer (nylon-6 / 11), caprolactam / ω-aminononanoic acid polymer (nylon-6,9), caprolactam / hexamethylene diammonium adipate copolymer (nylon-6 / 6) , 6), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon-6 / 6,6)
/ 6, 12), polymetaxylylene adipamide (hereinafter, referred to as
MXD-6), or aromatic nylon which is a polymer of hexamethylenediamine and m, p-phthalic acid. These polyamides can be used alone or in combination of two or more.

Among these polyamides, polymethaxylylene adipamide (MXD-
6) is preferred.

Among the barrier resins (A) exemplified above, ethylene-vinyl alcohol copolymer (EVOH) and polymethaxylylene adipamide (MXD-6) are preferred from the viewpoint of gas barrier properties. It is preferable to use EVOH.

The resin composition constituting the stretched film of the present invention may optionally contain a thermoplastic resin other than the barrier resin (A) as long as the effects of the present invention are not impaired. As the thermoplastic resin, various polyolefins (polyethylene, polypropylene, poly 1-butene, poly 4
-Methyl-1-pentene, an ethylene-propylene copolymer, a copolymer of ethylene and an α-olefin having 4 or more carbon atoms, a copolymer of a polyolefin and maleic anhydride,
Ethylene-vinyl ester copolymer, ethylene-acrylate copolymer, or modified polyolefin obtained by graft-modifying these with an unsaturated carboxylic acid or a derivative thereof), polyurethane, polyacetal, and the like.

However, from the viewpoint of the gas barrier properties of the stretched film made of the resin composition, it is preferable that the amount of the thermoplastic resin other than the barrier resin (A) is small. In the thermoplastic resin constituting the resin composition, the content of the thermoplastic resin other than the barrier resin (A) is preferably 20% by weight or less, more preferably 10% by weight or less, and more preferably 5% by weight. The content is more preferably not more than 3% by weight, particularly preferably not more than 3% by weight, and most preferably, the thermoplastic resin constituting the resin composition is substantially composed of only the barrier resin (A).

The particle size used in the present invention is 0.5 to 2.5.
Preferred examples of the μm inorganic filler (B) include, but are not limited to, mica, sericite, glass flake, and talc. These inorganic fillers can be used alone or in combination. Among the inorganic fillers (B) exemplified above, it is particularly preferable to use talc from the viewpoint of obtaining a stretched film having a large weight average aspect ratio (α) and particularly excellent light blocking properties and gas barrier properties.

The weight average aspect ratio (α) of the inorganic filler (B) used in the present invention is preferably 5 or more, more preferably 10 or more, and most preferably 13 or more.
The weight average aspect ratio (α) of the inorganic filler (B) is 5
If it is less than 3, the effects of imparting oxygen barrier properties and light blocking properties may be reduced, and the effect of improving pinhole resistance may be insufficient.

The weight average aspect ratio (α) of the inorganic filler (B) in the present invention is defined as the weight average flake diameter L
And a value calculated using the formula (1) from the weight average flake thickness d of the inorganic filler measured by the following method. α = L / d (1) The weight average flake diameter L of the inorganic filler (B) in the formula (1) is determined by classifying the powder with a micro sieve or sieve having various openings, and determining the result by Rosin-Rammlar.
Micro sieve or sieve mesh L through which 50% by weight of the total weight of the powder used for measurement is plotted on a diagram.
_This is a value equivalent to ₅₀ . That is, the weight average flake diameter L of the powder is defined by the formula (2) or (3). L = L ₅₀ (in the case of micro sieve) (2) L = 2 ^0.5 · L ₅₀ (in the case of sieve) (3) Here, a portion of the powder having a large particle size is classified by the sieve. The portion having a small particle size is classified by a micro sieve.

On the other hand, the weight average flake thickness d of the inorganic filler refers to C.I. E. FIG. Capes et al. Reported a single-particle water surface membrane method {C. E. FIG. Capes and R.A. C. Cole
man. Ind. Eng. Chem. Fundam. ,
Vol. 12, No. 2, P. 124-126 (197
3) The occupied area S of the flake on the water surface measured by｝
Is a value calculated from the following equation (4) using d = W / {ρ (1-ε) · S} (4) where W is the weight of the powder used for measurement, ρ is the specific gravity of the powder,
(1-.epsilon.) Is the occupancy when the powder is in the state of closest packing on the water surface, and the value of the powder was calculated by setting (1-.epsilon.) To 0.9.

In order to improve the affinity with the barrier resin (A) and prevent perforation during stretching, the surface of the inorganic filler (B) is treated with a surface treatment agent (for example, a silane coupling agent, It is also preferable to perform a treatment with a titanate-based coupling agent, an aluminum-based coupling agent, or the like.

The particle size of the inorganic filler (B) used in the present invention is 0.5 to 2.5 μm, preferably 0.8 to 2.5 μm.
To 2.5 μm, more preferably 0.8 to 1.8 μm. In addition, the particle diameter of the inorganic filler (B) in the present invention refers to the above-mentioned weight average flake diameter L. When the particle size of the inorganic filler (B) is less than 0.5 μm, the light blocking property, particularly the visible light blocking property, becomes insufficient.

The inorganic filler (B) has a particle diameter of 2.
It is extremely important that the thickness be 5 μm or less. The stretched film of the present invention is stretched at least twice in at least one axial direction in order to obtain excellent ultraviolet and visible light shielding properties and gas barrier properties. As a result of detailed studies by the present inventor, the barrier resin (A) was obtained under the mild stretching conditions described in the above-mentioned Japanese Patent Application Laid-Open No. 5-193076, in which a multilayer sheet was thermoformed to obtain a multilayer container. The particle diameter of the contained inorganic filler (B) is not particularly limited,
When performing high-magnification stretching as required in the present invention,
It has been first clarified that it is essential that the particle size of the inorganic filler (B) is 2.5 μm or less. When the particle size of the inorganic filler (B) exceeds 2.5 μm, the stretchability of the resin composition comprising the barrier resin (A) and the inorganic filler (B) becomes unsatisfactory. As a result, the film may be broken by the stretching treatment, and the film thickness after stretching may be non-uniform.

The stretched film of the present invention is particularly preferably a method of laminating the stretched film and a film or sheet of another substrate using a known adhesive such as an organic titanium compound, an isocyanate compound or a polyester compound. It is used as a multilayer structure obtained by laminating by a so-called dry lamination method. In order to obtain such a multilayer structure, a single-layer raw film formed by molding a resin composition comprising the barrier resin (A) and the inorganic filler (B) used in the present invention is at least doubled in at least one axial direction. It is preferable to produce a film formed by the above stretching. As the stretched film to be laminated on the base material, a stretched multilayer structure containing at least one resin composition layer composed of the barrier resin (A) and the inorganic filler (B) may be used. From the viewpoint that stretching can be performed under the best stretching conditions, an embodiment in which a single-layer raw film formed by molding a resin composition is stretched is particularly preferable. By stretching under favorable conditions for the resin composition, it is possible to further improve the ultraviolet light shielding property, the visible light blocking property, the gas barrier property and the pinhole resistance.

When a multilayer structure is used as the raw material for stretching, the other layers laminated on the resin composition layer also need to be stretched at the same time. May not be possible. Also,
When a multilayer structure is used as the stretched raw material, since at least one of the layers adjacent to the resin composition layer is always stretched, it is necessary to use a non-stretched layer on both sides of the layer adjacent to the resin composition layer. It is necessary to use a stretched film formed by stretching a single-layer stretched raw material obtained by molding a resin composition.

Therefore, the resin composition comprising the barrier resin (A) and the inorganic filler (B) used in the present invention preferably exhibits excellent stretchability even in the case of a single layer of the resin composition. It is more difficult to stretch a single-layer raw material than a multilayer raw material, and from the viewpoint of requiring high stretchability, the inorganic filler (B) used in the present invention has a particle diameter of 2.5 μm or less. It is vitally important.

The stretched film of the present invention has a barrier resin (A) content of 70 to 95% by weight and a particle size of 0.5 to 2.5%.
It is obtained by molding a resin composition comprising 5 to 30% by weight of an inorganic filler (B) having a thickness of 5 μm. (A) in the resin composition
The mixing ratio of (A) and (B) is preferably (A) 80 to 93% by weight and (B) 7 to 20% by weight, more preferably (A) 85 to 93% by weight and (B) 7 to 15% by weight. weight%
It is.

If the content of (B) is more than 30% by weight, sufficient stretchability cannot be obtained when stretching a film of the resin composition, and the surface irregularities may become severe. The film may be broken. Also,
When laminating with another substrate or the like, wrinkles may frequently occur due to poor surface shape.

In the present invention, it is extremely important that the content of (B) is 5% by weight or more. (B)
If the content is less than 5% by weight, sufficient effects of shielding visible light and ultraviolet light, gas barrier properties and bending resistance cannot be obtained.

JP-A-11-227118 discloses that E
A stretched film which has at least two layers of a layer containing 0.05 to 0.5% by weight of talc in VOH and a layer made of polyamide and is simultaneously biaxially stretched is described. Such a stretched film has pinhole resistance,
It describes that it has excellent gas barrier properties. However, as apparent from a comparison between Example 1 and Comparative Example 1 described in the publication, when the content of talc to be mixed with EVOH is 0.05 to 0.5% by weight, the obtained stretched film is obtained. Does not improve gas barrier properties, nor does it improve pinhole resistance. Further, the document describes that when a composition obtained by adding 0.60% by weight of talc to EVOH is used, the number of pinholes generated increases (Comparative Example 3 of the publication).

The publication also describes that the addition of an ionomer resin to a composition comprising EVOH improves pinhole resistance. As is clear from comparison of Nos. 4 to 6, while the pinhole resistance is improved by the addition of the ionomer resin, the gas barrier property of the stretched film is reduced. As described above, in a stretched film made of EVOH, there has not been a technique for simultaneously improving the gas barrier property and the pinhole resistance, and development of such a technique has been strongly desired.

The inventors of the present invention have conducted intensive studies and have found that the barrier resin (A) is composed of 70 to 95% by weight and the inorganic filler (B) having a particle size of 0.5 to 2.5 μm is composed of 5 to 30% by weight. It has been found that a stretched film stretched at least twice in at least one axial direction is excellent not only in the function of shielding visible light and ultraviolet light, but also in the gas barrier property and the bending resistance, and has completed the present invention. .

As is apparent from Comparative Examples 1 and 2 of the present application, when the film made of EVOH is stretched, the pinhole resistance is improved about four times as compared with the case where it is not stretched (measurement conditions: 23). C.-50% RH) and the oxygen permeation amount becomes 0.6 times, and the gas barrier properties are improved to some extent (measurement conditions: 20.degree. C.-65% RH).

However, when a film (Example 1 of the present application) obtained by stretching a resin composition comprising 90% by weight of EVOH and 10% by weight of talc is used, it is about 7 times as large as a film made of only unstretched EVOH. It was found that the pinhole resistance was improved (measurement conditions: 23 ° C-5
0% RH). It is extremely surprising that the effect of improving the pinhole resistance by stretching is greatly improved by adding a specific amount of talc.

Further, the oxygen permeability of the film described in Example 1 of the present application is about one fifth of that of the film described in Comparative Example 1 (measurement conditions: 20 ° C.-65% RH), and the gas barrier property is extremely remarkable. Has been improved. As described above, the stretched film of the present invention is not only excellent in light blocking properties but also has extremely high pinhole resistance and gas barrier properties, and is extremely useful for applications such as paper containers and vacuum heat insulating materials. Things.

In order to achieve the effects of the present invention, it is essential that the resin composition constituting the film contains a specific amount of the inorganic filler (B) as described above, and furthermore, at least in the uniaxial direction. It is essential that the stretched film be stretched twice or more. Even when the resin composition is composed of 70 to 95% by weight of the barrier resin (A) and 5 to 30% by weight of the inorganic filler (B), the pinhole resistance is hardly improved unless the stretching treatment is performed. However, the gas barrier properties are not improved at all (see Comparative Example 3 of the present application).

The resin composition used in the present invention comprises a barrier resin (A) and an inorganic filler (B) having a particle diameter of 0.5 to 2.5 μm, but the production method is not particularly limited. The method of kneading the barrier resin (A) and the inorganic filler (B) is not particularly limited, and the components (A) and (B) are collectively blended using a known tumbler, Henschel mixer or the like, and then pelletized by a melt extruder. How to do (A)
The method of forcibly feeding (B) from the middle of the melt extruder to form a melt-kneaded pellet is exemplified as a suitable method.

In particular, if the blend is once pelletized using a vent-type single-screw extruder or a vent-type twin-screw extruder having a kneading section, the dispersibility of (B) with respect to (A) is further improved. Particularly preferred from the viewpoint.

[0061] Barrier resin (A) and inorganic filler (B)
When the mixture consisting of is blended at once using a known tumbler, Henschel mixer or the like, it is preferable to use a material obtained by previously pulverizing the barrier resin (A) to 20 to 40 mesh. By adopting such a method, the dispersibility of (B) in (A) is improved, and classification of the mixture of (A) and (B) in the course of being supplied to the extruder can be prevented.

The inorganic filler (B) is replaced with a barrier resin (A)
When kneading, it is desirable to dry the water content to 0.3% or less. By performing such an operation, it is possible to avoid that the barrier resin (A) used in the present invention reacts with moisture in the melt extruder to easily generate lumps and obtain good pellets. . In addition, in the melt compounding operation, there is a possibility that the blend becomes non-uniform, gels and butters may be generated and mixed, so that the blend pelletization is performed using an extruder with a high kneading degree as much as possible, and the hopper port is closed. It is desirable to seal with nitrogen gas and extrude at a low temperature.

The stretched film of the present invention can be obtained by stretching the stretched raw material obtained by melt-molding the resin composition obtained by the method exemplified above at least twice in the uniaxial direction. The method for producing the stretched raw material is not particularly limited, but a production method in which a film or sheet obtained by melt molding is quenched is particularly preferable. By rapidly cooling the film or sheet, it is possible to suppress the promotion of crystallization while the film or sheet immediately after production is cooled and solidified from a molten state, and the stretchability of the stretched raw material can be improved. The method for rapidly cooling the film or sheet obtained by melt molding is not particularly limited, and a known water cooling method, air cooling method, metal roll contact method and the like are exemplified as suitable ones.

The stretched film of the present invention is prepared by melting a stretched raw material obtained by melt-molding a resin composition comprising a barrier resin (A) and an inorganic filler (B) in at least one axial direction.
It is obtained by stretching at least twice. It is extremely important that the film is stretched at least twice in the uniaxial direction,
When the stretching ratio is less than 2, the effect of the present invention, that is, excellent in the function of shielding visible light and ultraviolet light and the gas barrier property, cannot be exhibited.

Hitherto, it has been widely known that stretching a film made of a barrier resin (such as EVOH) improves gas barrier properties. However, the barrier resin (A) 70 to 95% by weight and the particle size 0.5 to
A stretched film obtained by stretching a stretched raw fabric comprising a resin composition comprising 5 to 30% by weight of 2.5 μm inorganic filler (B) at least twice in at least one direction has not been known so far. It has been clarified for the first time that the stretched film exhibits extremely excellent gas barrier properties.

Although a film consisting of only a barrier resin has almost no light-blocking property, the addition of an inorganic filler makes it possible to remarkably improve the light-blocking property. However, a film obtained by adding an inorganic filler to a barrier resin shows excellent light blocking properties when used in a single layer, but has a small internal haze (see Comparative Example 3 of the present application), and the film is used as an intermediate layer. The light blocking properties of the multilayer film were unsatisfactory. On the contrary,
70 to 95% by weight of the barrier resin (A) and a particle size of 0.
The stretched film of the present invention, which comprises 5 to 30% by weight of an inorganic filler (B) having a thickness of 5 to 2.5 μm and is stretched at least twice in the uniaxial direction, has a sufficient light-shielding property and a sufficient internal haze. Thus, even when the stretched film was used as an intermediate layer of a multilayer film, excellent light blocking properties could be maintained.

When the stretched raw material is uniaxially stretched, it is essential that the stretching ratio is at least 2 times, preferably at least 2.5 times, more preferably at least 3 times. Stretching may be either uniaxial stretching or biaxial stretching, but biaxial stretching is preferred from the viewpoint of improving the gas barrier properties and mechanical strength of the stretched film. When the stretched raw material is biaxially stretched, the area magnification is preferably 3 times or more, more preferably 4 times or more.
Stretching at least twice, particularly preferably at least six times, is preferable from the viewpoint of improving the gas barrier properties and mechanical strength.

As a method of stretching the stretched raw material, a known stretching method can be adopted. Although there is a method of uniaxial or biaxial stretching by a double bubble method, a tenter method, a roll method, or the like, the tenter method is preferable because the film thickness accuracy is excellent. As the stretching method, after first stretching in the longitudinal direction with a longitudinal stretching machine combining several different rolls, it may be stretched in the transverse direction with a tenter type stretching machine, or conversely, after stretching in the transverse direction first, It may be stretched in the direction. Also,
A method of simultaneous biaxial stretching with a tenter-type stretching machine may be used.

The stretching temperature is not particularly limited.
It is preferable to perform the treatment at a temperature equal to or lower than the melting point of the barrier resin (A) used in the present invention from the viewpoint of light blocking properties. This tendency is particularly strong when the barrier resin (A) is made of EVOH. When the barrier resin (A) is made of EVOH, the stretching temperature is 20 ° C. higher than the melting point of EVOH used.
Or lower, more preferably 40 ° C. or lower than the melting point of EVOH, and 60 ° C. lower than the melting point of EVOH.
More preferably, the melting point is lower than the melting point of EVOH.
It is particularly preferable that the temperature is lower than 0 ° C. By lowering the stretching temperature, stretching itself may be difficult,
It is preferable to perform a stretching treatment using a stretched raw fabric in a water-containing state. There is no particular limitation on the method for producing a stretched raw fabric in a water-containing state, and a method of melt-forming a resin composition pellet containing water or a method of immersing a stretched raw fabric in warm water (preferably at 60 to 90 ° C.) to wet the raw material is used. A suitable method is exemplified.

The melting point of the barrier resin (A) in the present invention refers to a value obtained by measuring the barrier resin (A) according to the method described in JIS K7121 (the temperature is calibrated using iridium and lead. Was). The stretching temperature in the present invention refers to a value obtained by measuring the surface temperature of the stretched raw material immediately before stretching after heating the stretched raw material for a predetermined time.

The stretched film of the present invention is preferably subjected to a heat treatment from the viewpoint of further improving gas barrier properties and mechanical strength. On the other hand, a stretched film that is not subjected to a heat treatment is suitably used as a heat-shrinkable film. The heat treatment temperature in the present invention refers to a value obtained by measuring the surface temperature of the multilayer structure immediately after heating the stretched film for a predetermined time in the heat treatment step. Although the heat treatment temperature is not particularly limited, it is preferable to perform the heat treatment under the condition satisfying the following expression (1). 0 ≦ T _m −T ₁ ≦ 80 (1) where Tm: melting point (° C.) of the barrier resin (A) T ₁ : heat treatment temperature (° C.) The heat treatment temperature in the present invention refers to a value obtained by measuring the surface temperature of the stretched film immediately after heating the stretched film for a predetermined time in the heat treatment step.

The thickness of the stretched film of the present invention is not particularly limited, but is preferably 3 to 100 μm. 3μ
If it is less than m, the mechanical strength of the film may be unsatisfactory, and pinholes and the like may easily occur. If it exceeds 100 μm, the intended use may be limited, and when obtaining a stretched film having a high stretch ratio, the thickness of the stretched raw material is increased, so that uniform stretching may be difficult. . The thickness of the film is more preferably 5 to 50 μm, particularly preferably 5 to 20 μm
It is. Even with such a film thickness, a film made of the resin composition of the present invention is suitable from the viewpoint of a sufficient visible light and ultraviolet ray shielding function and gas barrier properties.

In the stretched film of the present invention having a thickness of 3 to 100 μm, it is particularly preferable that the total haze is 50% or more from the viewpoint of sufficiently exhibiting the effect of the present invention of a visible light blocking function. The total haze of the film is 60
%, More preferably at least 65%. Further, the difference between the total haze and the internal haze of the film is preferably 30% or less, and more preferably 20% or less. When the difference between the total haze and the internal haze of the film is 30% or less, even when the film is laminated on a film or sheet made of another thermoplastic resin, a particularly good visible light blocking function can be exhibited. It is possible.

Further, in the stretched film of the present invention having a thickness of 3 to 100 μm, the visible light transmittance is 50% or less and the ultraviolet light transmittance is 30% or less. Is preferred. The visible light transmittance is more preferably 40% or less, and still more preferably 3% or less.
0% or less, particularly preferably 20% or less. Further, the UV transmittance is more preferably 20% or less, and further preferably 10% or less. In the present invention, the visible light transmittance is the light transmittance at a wavelength of 700 nm, and the ultraviolet light transmittance is the light transmittance at a wavelength of 350 nm.

The stretched film of the present invention can be put to practical use as a multilayer structure having at least one layer made of the stretched film of the present invention, in addition to a single-layer product consisting of the stretched film alone. The layer structure of the multilayer structure is such that a layer composed of the stretched film of the present invention is E, a layer composed of an adhesive resin is Ad, and a layer composed of a thermoplastic resin is T.
The expression includes E / Ad / T, T / Ad / E / Ad / T, but is not limited thereto. Each layer may be a single layer or may be a multilayer in some cases. When the thermoplastic resin layers are provided on both outer layers, they may be different types or may be the same. further,
A recovered resin layer made of scrap such as trim generated at the time of molding may be separately provided, or the recovered resin may be blended with the thermoplastic resin layer. Although there is no particular limitation on the thickness configuration of the multilayer structure, the thickness ratio of the layer made of the stretched film to the total layer thickness is preferably 2 to 20% in consideration of moldability, cost, and the like.

The method for producing the above-mentioned multilayer structure is not particularly limited. For example, the method of melt-extruding a thermoplastic resin into the stretched film of the present invention, the method of forming a barrier resin (A) 70-
A method in which a resin composition of 95% by weight and 5 to 30% by weight of an inorganic filler (B) having a particle size of 0.5 to 2.5 μm and another thermoplastic resin are co-extruded, and then stretched at least twice in at least one axial direction. Further, a method (dry laminating method) of laminating the stretched film of the present invention and another substrate with a known adhesive such as an organic titanium compound, an isocyanate compound, or a polyester compound (dry laminating method) and the like are cited as preferable examples. However, among these, the method of dry laminating the stretched film of the present invention and another substrate is particularly preferable as described above. In addition, as a base material, a film or sheet made of a thermoplastic resin, paper, or the like is exemplified as a suitable material.

The thermoplastic resin used includes linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene and propylene-α. -Olefin copolymer (carbon number 4
Α-olefins), polybutene, polypentene and other olefins alone or copolymers thereof, polyesters such as polyethylene terephthalate, polyester elastomers, polyamide resins such as nylon-6, nylon-6,6, polystyrene, polyvinyl chloride , Polyvinylidene chloride, acrylic resin, vinyl ester resin, polyurethane elastomer, polycarbonate, chlorinated polyethylene, chlorinated polypropylene and the like.
Among them, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene, and polyester are preferably used.

The stretched film of the present invention, and a multilayer structure comprising at least one layer comprising the stretched film,
Since it has excellent gas barrier properties and excellent shielding properties against visible light and ultraviolet light, it is suitably used as a container for storing various foods, alcoholic beverages, industrial goods which are not susceptible to oxidative deterioration, and the like. The form of the container is not particularly limited, and a flexible pouch, a paper container and the like are exemplified as preferable ones, and a paper container is particularly preferable.

Hitherto, aluminum foil has been laminated on a paper container filled with contents that are easily degraded by visible light and ultraviolet rays, from the viewpoint of providing a function of blocking visible light and ultraviolet rays and a gas barrier property with a thin film thickness. However, the multilayer structure using the aluminum foil has a problem in both recyclability and incineration as described above.
However, by using a paper container including a layer made of the resin composition of the present invention, recyclability is greatly improved, and the problem of incineration is solved.

As the layer constitution of the paper container, a layer composed of a thermoplastic resin is represented by T, a layer composed of the stretched film of the present invention by E, a layer composed of an adhesive resin or a layer composed of an adhesive by Ad, and paper by P. , T / P / Ad / E / Ad / T, T / P
Examples include layer configurations such as / Ad / E / Ad / P / T and T / P / Ad / E / Ad, but it is not limited to adding any other layer to these layers at all and limited to the above examples. It does not do.

Further, lamination with a single-layer structure or a multilayer structure including a colored film or sheet, steel plate, or plywood is also possible. When laminated on these single-layer structures or multilayer structures, they are used for surface protection and matte effect, etc., and are preferably used for wallpaper, decorative boards, building materials, signboards, bird and beast damage prevention tools, etc. Is exemplified. In particular, since the layer made of the resin composition of the present invention is excellent in matting effect and embossability, the multilayer structure including the resin composition layer of the present invention is suitably used as a wallpaper or decorative board.

Further, since the stretched film of the present invention is excellent in a function of shielding visible light and ultraviolet light and gas barrier properties, a multilayer structure including at least one layer made of the stretched film is extremely suitable as a vacuum heat insulating material. As described above, conventionally, a multilayer structure including at least one layer made of aluminum foil has been used for a vacuum heat insulating material in order to provide gas barrier properties and light blocking properties, but problems remain in recyclability and incineration. In addition to this, there still remains a problem of deterioration in heat insulation performance due to a so-called heat bridge.
However, these problems can be solved at once by using a multilayer structure including at least one layer made of the stretched film of the present invention.

[0083]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Various test methods in the present invention were performed according to the following methods.
All parts and percentages are by weight unless otherwise specified.

<Oxygen Permeability> MODERN CONTR
OLS INC. MOCONOX Oxygen Permeation Analyzer
-Measured according to JIS K7126 (isobaric method) under the condition of 20 ° C. and 65% RH using Model TRAN2 / 20. The oxygen permeation amount referred to in the present invention is the oxygen permeation amount (ml / m ² · day · atm) measured at an arbitrary film thickness of a film composed of a single layer by a film thickness of 20 μm
Value converted to the amount of oxygen permeation at (ml ・ 20μm / m ²・
day.atm).

<Haze> Integral formula H.I. T. The haze of the film obtained in each of the examples and comparative examples was measured using an R meter according to JIS D8741. The internal haze is a value measured by applying silicone oil to a thickness of about 2 μm on both surfaces of the film obtained in each of Examples and Comparative Examples.

<Light Transmittance> Using a self-recording spectrophotometer UV-2100 manufactured by Shimadzu Corporation, the light transmittance was measured according to the method described in JIS K7105, and the light transmittance at a wavelength of 700 nm was determined from the measurement diagram. (Visible Light Transmittance)
And the light transmittance (UV transmittance) at a wavelength of 350 nm was determined.

<Appearance> After stretching, the appearance and surface smoothness of the heat-treated film were visually evaluated and judged according to the following criteria. Judgment: Standard ◎ (Passed): No breakage and smooth surface. ○ (Pass): There is no tear and the surface is slightly rough, but there is no practical problem. X (fail): There is tearing and the surface is rough.

Example 1 As a barrier resin (A), an ethylene content of 32 mol% was used.
EVOH having a saponification degree of 99.5 mol% (melting point: 183 ° C.),
Talc having a particle diameter of 1.5 μm and a weight average aspect ratio of 15 (manufactured by Fuji Talc Co., Ltd.) as the inorganic filler (B)
LMS-200) was used. After mixing 90 parts by weight of the EVOH and 10 parts by weight of the talc with a tumbler,
It pelletized at 230 degreeC using the vent-type twin-screw extruder. The obtained pellet was melt-extruded from a flat die at 230 ° C. using a single-screw extruder, and was brought into contact with a cooling roll at a temperature of 20 ° C. to obtain a stretched raw material having a thickness of 135 μm. The surface of the obtained stretched raw material was smooth and free of bumps, and the accuracy of thickness and thinness was good.

Then, the moisture of the stretched raw material was adjusted to 15%, and a biaxial stretching device manufactured by Toyo Seiki Co., Ltd. was used.
At 20 ° C., at a stretching temperature of 80 ° C., at a stretching ratio of 9 (longitudinal 3.0 × horizontal 3.0), and at a stretching speed of 1 m / min. To obtain a stretched film having a thickness of 15 μm. . The obtained stretched film was fixed to a wooden frame, and the temperature was 140 ° C. · 10
Heat treatment for minutes. The single-layer stretched film has an oxygen transmission rate of 0.04 ml / 20 μm / m ² · day · atm, a total haze of 70%, an internal haze of 53%, a visible light transmittance of 14%, and an ultraviolet transmittance of 6%. %Met.

The obtained stretched film is 21 cm × 30 c
m, and humidified to 23 ° C-50% RH.
According to STM F392-74, it was bent 300 times (23 ° C.-50% RH) using a gelbo flex tester manufactured by Rigaku Corporation. The film after bending is P
Put on a PC paper (KOKUYO KB-239, A4) and apply 1000 g of distilled water to a red pigment (manufactured by Sumitomo Chemical, N-4).
G) Red ink prepared by dissolving 5 g is soaked in cloth and applied to the upper surface of the film, and the pinhole portion is
Transferred to PC paper.

The number of pinholes of the film transferred to the paper surface as described above was measured for each size (n = 2). Table 3 shows the evaluation results.

Further, 45 stretched films cut into a size of 21 cm × 30 cm were prepared, and each film was conditioned at 23 ° C. and 50% RH.
Using a gelbo flex tester manufactured by Rigaku Kogyo Co., Ltd., the number of bending times was 200 times, 225 times,
50 times, 300 times, 350 times, 400 times, 500 times, 6 times
After bending 25 times and 750 times, the number of pinholes was measured. At each bending frequency, the measurement was performed 5 times, and the average value was defined as the number of pinholes.

The number of bends (P) is plotted on the abscissa and the number of pinholes (N) is plotted on the ordinate. The above measurement results are plotted, and the number of bends when the number of pinholes is one (Np1) is extrapolated. (See FIG. 1). Np1 of the stretched film of this example
Was 230 times.

A polyethylene film having a thickness of 60 μm (Icelo Chemical Co., Ltd.)
Manufactured by Suzuron Co., Ltd.). The adhesive was laminated using Takeda Pharmaceutical Co., Ltd., Takelac, A385 / A50 to a coating amount of 4 g / m ² , a temperature of 70 ° C., and aging at 40 ° C. for 5 days. The composite film had no delamination and had a good film surface. The visible light transmittance of the composite film was 42%, and the ultraviolet light transmittance was 19%.

Example 2 A stretched film was produced in the same manner as in Example 1 except that EVOH (melting point: 191 ° C.) having an ethylene content of 27 mol% and a saponification degree of 99.5% was used as the barrier resin (A). Were prepared and various physical properties were evaluated. Table 1 shows the evaluation results.

Example 3 A stretched film was prepared in the same manner as in Example 1 except that EVOH (melting point: 160 ° C.) having an ethylene content of 47 mol% and a saponification degree of 99.5% was used as the barrier resin (A). Were prepared and various physical properties were evaluated. Table 3 shows the evaluation results.

Example 4 A stretched film was prepared in the same manner as in Example 1 except that talc having a particle diameter of 2 μm (LMK-100, manufactured by Fuji Talc Co., Ltd.) was used as the inorganic filler (B). Physical properties were evaluated. Table 1 shows the evaluation results.

Example 5 The same procedure was carried out except that the amount of the barrier resin (A) and the amount of the inorganic filler (B) were changed to 80 parts by weight of the barrier resin (A) and 20 parts by weight of the inorganic filler (B). A stretched film was prepared in the same manner as in Example 1, and various physical properties were evaluated. Table 1 shows the evaluation results.

Example 6 Example 1 was repeated except that MXD-6 (MX Nylon 6007 manufactured by Mitsubishi Gas Chemical Company) was used as the barrier resin (A).
A film was prepared in the same manner as described above, and various physical properties were evaluated.
Table 1 shows the evaluation results.

Example 7 Nylon-6 (Ube Industries, Ltd.) was used as the barrier resin (A).
Example 1 except that UBE nylon 1024B) was used.
A film was prepared in the same manner as described above, and various physical properties were evaluated.
Table 1 shows the evaluation results.

[0101]

[Table 1]

Comparative Example 1 EVOH (melting point: 183 ° C.) having an ethylene content of 32 mol% and a saponification degree of 99.5 mol% was subjected to 230-screw extrusion using a single screw extruder.
Extruded at ℃ to obtain a 20 μm thick unstretched film. Further, the oxygen permeation amount of the single-layer film is 0.20 ml · 2
0 μm / m ² · day · atm, the total haze was 1%, the internal haze was 1%, the visible light transmittance was 91%, and the ultraviolet light transmittance was 87%.

Forty unstretched films cut into 21 cm × 30 cm were prepared, and each film was
After adjusting the humidity to 3 ° C.-50% RH, ASTM F392
According to -74, using a gelbo flex tester manufactured by Rigaku Kogyo Co., Ltd., the number of bending times is 25, 30, 35, 4
After bending 0 times, 50 times, 60 times, 80 times, and 100 times, the number of pinholes having a diameter of 2 mm or more was measured.
For each number of bends, measure the number of pinholes by 5
Times, and the average value was defined as the number of pinholes.

The number of bends (P) is plotted on the abscissa and the number of pinholes (N) is plotted on the ordinate. The above measurement results are plotted, and the number of bends when the number of pinholes is one (Np1) is extrapolated. (See FIG. 2). Np of unstretched film of this comparative example
One was 32 times.

A polyethylene film having a thickness of 60 μm (manufactured by Aicello Chemical Co., Ltd., Suzuron) was attached to both sides of the unstretched EVOH film prepared above to form a composite film. The adhesive was Takeda Pharmaceutical, Takelac, A385
The coating amount was 4 g / m ² using / A50, the laminate was laminated at a temperature of 70 ° C, and aged at 40 ° C for 5 days. The visible light transmittance of the composite film was 83%, and the ultraviolet light transmittance was 63%.

Comparative Example 2 EVOH (melting point: 183 ° C.) having an ethylene content of 32 mol% and a saponification degree of 99.5 mol% was subjected to 230-screw extrusion using a single screw extruder.
The mixture was melt-extruded from a flat die at a temperature of 20 ° C. and brought into contact with a cooling roll at a temperature of 20 ° C. to obtain a 135 μm-thick raw stretched film. The surface of the obtained stretched raw material was smooth and free of bumps, and the accuracy of thickness and thinness was good.

Next, the moisture of the stretched raw material was adjusted to 15%, and a biaxial stretching device manufactured by Toyo Seiki Co., Ltd. was used.
20 ° C., stretching temperature 80 ° C., stretching ratio 9 times (length 3.
(× 0 × 3.0 ×) and simultaneous biaxial stretching at a stretching speed of 1 m / min to obtain a 15 μm thick stretched film. The obtained stretched film was fixed to a wooden frame and heat-treated at a temperature of 140 ° C. for 10 minutes. The single-layer stretched film has an oxygen transmission rate of 0.13 ml / 20 μm / m ² · day · atm, a total haze of 0.3%, an internal haze of 0.1%, a visible light transmittance of 92%, and ultraviolet rays. The transmittance was 90%.

The obtained stretched film is 21 cm × 30 c
m, and humidified to 23 ° C-50% RH.
According to STM F392-74, it was bent 300 times (23 ° C.-50% RH) using a gelbo flex tester manufactured by Rigaku Corporation. The film after bending is P
Put on a PC paper (KOKUYO KB-239, A4) and apply 1000 g of distilled water to a red pigment (manufactured by Sumitomo Chemical, N-4).
G) Red ink prepared by dissolving 5 g is soaked in cloth and applied to the upper surface of the film, and the pinhole portion is
Transferred to PC paper.

The number of pinholes of the film transferred to the paper surface as described above was measured for each size (n = 2). Table 3 shows the evaluation results.

Further, 45 sheets of the above-mentioned stretched film cut into 21 cm × 30 cm were prepared, and each film was conditioned at 23 ° C.-50% RH.
Using a gelbo flex tester manufactured by Rigaku Kogyo Co., Ltd. according to
25 times, 150 times, 175 times, 200 times, 225 times, 2
After bending 50 times and 300 times, the number of pinholes having a diameter of 2 mm or more was measured. At each bending frequency, the measurement was performed 5 times, and the average value was defined as the number of pinholes.

The number of flexures (P) is plotted on the abscissa and the number of pinholes (N) is plotted on the ordinate. The above measurement results are plotted, and the number of flexures (Np1) when the number of pinholes is one is extrapolated. (See FIG. 3). Np1 of the stretched film of this comparative example
Was 130 times.

A polyethylene film having a thickness of 60 μm (Icelo Chemical Co., Ltd.)
Manufactured by Suzuron Co., Ltd.). The adhesive was laminated using Takeda Pharmaceutical Co., Ltd., Takelac, A385 / A50 to a coating amount of 4 g / m ² , a temperature of 70 ° C., and aging at 40 ° C. for 5 days. The visible light transmittance of the composite film was 82%, and the ultraviolet light transmittance was 65%.

Comparative Example 3 Ethylene content of 32 mol% as the barrier resin (A)
EVOH having a saponification degree of 99.5 mol% (melting point: 183 ° C.),
Talc having a particle diameter of 1.5 μm and a weight average aspect ratio of 15 (manufactured by Fuji Talc Co., Ltd.) as the inorganic filler (B)
LMS-200) was used. After mixing 90 parts by weight of the EVOH and 10 parts by weight of the talc with a tumbler,
It pelletized at 230 degreeC using the vent-type twin-screw extruder. The obtained pellets were extruded at 230 ° C. using a single-screw extruder to obtain a 20 μm-thick unstretched film. Also,
The oxygen permeation amount of the single-layer film is 0.20 ml · 20 μ
m / m ² · day · atm, total haze was 61%, internal haze was 25%, visible light transmittance was 20%, and ultraviolet transmittance was 12%.

Using the obtained unstretched film, the number of Np1 was determined in the same manner as in Comparative Example 1. Np1 of the unstretched film of this comparative example was 39 times.

A polyethylene film having a thickness of 60 μm (Suzuron, manufactured by Aicello Chemical Co., Ltd.) was laminated on both sides of the unstretched EVOH film prepared above to form a composite film. The adhesive was Takeda Pharmaceutical, Takelac, A385
The coating amount was 4 g / m ² using / A50, the laminate was laminated at a temperature of 70 ° C, and aged at 40 ° C for 5 days. The visible light transmittance of the composite film was 73%, and the ultraviolet light transmittance was 53%.

Comparative Example 4 Talc having a particle diameter of 6 μm and a weight average aspect ratio of 7 (PKP, manufactured by Fuji Talc Kogyo KK) was used as the inorganic filler (B).
Except for using -80), an attempt was made to produce a stretched film in the same manner as in Example 1, but the film appearance was poor.
The film was broken by stretching, the film appearance and surface smoothness were poor, and the film was not practical.

COMPARATIVE EXAMPLE 5 The same procedure was carried out except that the amounts of the barrier resin (A) and the inorganic filler (B) were changed to 60 parts by weight of the barrier resin (A) and 40 parts by weight of the inorganic filler (B). An attempt was made to produce a stretched film in the same manner as in Example 1, but the film was broken by stretching, the film appearance and surface smoothness were poor, and the film was not practical.

Comparative Example 6 Instead of talc having a particle diameter of 1.5 μm and a weight average aspect ratio of 15 (manufactured by Fuji Talc Co., Ltd., LMS-200), titanium oxide having a particle diameter of 0.25 μm (Ishihara Sangyo Co., Ltd.) was used.
Except that TYPAK CR60) was used, a stretched film was produced in the same manner as in Example 1, and various physical properties were evaluated.
Table 2 shows the evaluation results.

[0119]

[Table 2]

[0120]

[Table 3]

The stretched films of Examples 1 to 7 satisfying the constitution of the present invention exhibited excellent performances in both the function of shielding visible light and ultraviolet light and the gas barrier properties. On the other hand, in Comparative Example 1 using an unstretched EVOH film without using the inorganic filler (B) or Comparative Example 2 using a stretched EVOH film, the function of shielding visible light and ultraviolet light, the gas barrier property, and the pin resistance were improved. Sufficient performance was not obtained in any of the hole properties. Moreover, although it is composed of the barrier resin (A) and the inorganic filler (B), in Comparative Example 3 in which the stretching treatment is not performed, sufficient gas barrier properties and pinhole resistance cannot be obtained, and the internal haze is sufficiently large. Therefore, satisfactory light blocking properties could not be obtained, especially when a composite film with polyethylene was formed.

As is clear from the comparison of the gas barrier properties of the films obtained in Comparative Examples 1 and 2 of the present application, in the case of a film composed of only EVOH without containing an inorganic filler, a reduction in the amount of oxygen permeation by stretching was obtained. The effect is about 30%.

On the other hand, as is clear from the comparison of the gas barrier properties of the films obtained in Example 1 of the present application and Comparative Example 3, in the case of the film comprising the barrier resin (A) and the inorganic filler (B), the film was stretched. When the treatment is not performed, even though the inorganic filler (B) is added, the effect of improving the gas barrier property is hardly observed, but by performing the stretching,
It was possible to reduce the amount of oxygen permeation by about 80%.
As described above, the present inventors have clarified for the first time that the addition of the inorganic filler (B) significantly improves the effect of improving the gas barrier property by stretching, and from this viewpoint, the significance of the present invention is as follows. large.

While the stretched film of the present invention can obtain a sufficient internal haze (see Example 1), Comparative Example 3 using an unstretched film has a sufficient internal haze. No satisfactory light-shielding property was obtained when the composite film was formed with another thermoplastic resin or the like. By stretching at least twice in the uniaxial direction, the film composed of the barrier resin (A) and the inorganic filler (B) has a sufficient internal haze, and has excellent light blocking properties even when used as a laminate. It is not clear why it can be maintained, but such characteristics were first clarified by the present inventor, and from this viewpoint, the present invention is significant.

The inorganic filler (B) has a particle size of 2.
In the case of Comparative Example 4 exceeding 5 μm, and in the case of Comparative Example 5 in which the blending amount of the inorganic filler (B) exceeds 30% by weight, the stretchability of the stretched raw material is unsatisfactory, and tearing or the like is caused by stretching. The appearance and the surface smoothness were poor and were not practical.

Further, in the case of Comparative Example 6 in which the particle size of the inorganic filler (B) was less than 0.5 μm, sufficient visible light blocking properties and gas barrier properties could not be obtained.

EFFECTS OF THE INVENTION The stretched film of the present invention is excellent in the function of shielding visible light and ultraviolet light, gas barrier properties and bending resistance, and is suitable for containers of various foods, processed marine products, chemicals, cosmetics, etc., particularly preferably paper. In addition to being used as containers, it is suitably used for wallpaper, building materials, signboards, vacuum heat insulating materials, and the like.

[Brief description of the drawings]

FIG. 1 shows the stretched film produced in Example 1 at 23 ° C.
It is a figure which shows the relationship between the number of times of bending (N) and the number of generation of pinholes (P) in a Gelboflex tester at -50% RH.

FIG. 2 shows an unstretched film produced in Comparative Example 1;
It is a figure which shows the relationship between the number of times of bending (N) and the number of generation of pinholes (P) in a Gelboflex tester at -50% RH.

FIG. 3 shows the stretched film produced in Comparative Example 2 at 23 ° C.
It is a figure which shows the relationship between the number of times of bending (N) and the number of generation of pinholes (P) in a Gelboflex tester at -50% RH.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C08J 5/18 CEX C08J 5/18 CEX CFG CFG C08K 3/00 C08K 3/00 3/34 3/34 C08L 29/04 C08L 29/04 S 77/00 77/00 101/12 101/12 // B29K 55:00 B29K 55:00 77:00 77:00 105: 16 105: 16 303: 04 303: 04 B29L 7:00 B29L 7:00 9:00 9:00 F term (reference) 3E086 AD02 BA04 BA15 BA33 BB05 BB22 BB23 BB85 CA01 CA25 CA28 CA29 4F071 AA15X AA29X AA56 AA76 AB30 AF07 AF30 AH03 AH05 BA01 BB06 BB07 BC01 4F100 AA00A AC10AB AK01 BA10B CA23A CB00 DA01 DG10B EJ37A GB08 GB90 HB00 HB31 JA20A JD02A JK20 JN01A YY00A 4F210 AA04E AA19E AA29 AB11 AB16 AG01 AG03 AH48 AH56 AR20 QA03 QC01 QC05 QG01 CL1016 DJG1CL034

Claims (10)

[Claims] 1. An inorganic filler (B) 5 having a barrier resin (A) of 70 to 95% by weight and a particle diameter of 0.5 to 2.5 μm.
A stretched film comprising at least 30% by weight and stretched at least twice in a uniaxial direction. 2. The stretched film according to claim 1, wherein the barrier resin (A) is at least one selected from an ethylene-vinyl alcohol copolymer and polymethaxylylene adipamide. 3. The barrier resin (A) having an ethylene content of 5
The stretched film according to claim 1, which is an ethylene-vinyl alcohol copolymer having a mole percentage of 60% by mole and a saponification degree of 90% or more. 4. The stretched film according to claim 1, wherein the inorganic filler (B) is talc. 5. The stretched film according to claim 1, which has a thickness of 3 to 100 μm and a total haze of 50% or more. 6. A multilayer structure comprising at least one layer comprising the stretched film according to claim 1. 7. A multilayer structure obtained by laminating the stretched film according to claim 1 on a substrate by a dry lamination method. 8. A paper container comprising the multilayer structure according to claim 6. 9. A wallpaper or decorative board comprising the multilayer structure according to claim 6. 10. A vacuum heat insulating material comprising the multilayer structure according to claim 6.