JP2001301100A - Multilayered structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a multilayered structure excellent in oxygen barrier properties, offensive smell barrier properties and transparency. SOLUTION: A layer of a thermoplastic resin (D) other than a barrier resin (A) is laminated on at least the single surface of a layer of a resin composition (C) consisting of 100 parts by weight of the barrier resin (A) and 0.5-10 parts by weight of a deodorant (B) with a particle size of 0.5-10 μm and the obtained laminate is stretched at least uniaxially by twice or more to obtain the multilayered structure.

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 excellent oxygen barrier properties and odor barrier properties and excellent transparency.

[0002]

2. Description of the Related Art Hydrophobic thermoplastic resins such as polyolefins and polystyrenes are excellent in melt moldability, secondary processing properties, mechanical properties and economical efficiency. In the non-food field, it is widely used for daily necessities, home electric parts, automobile parts and the like. Further, there is a film using a resin having an oxygen barrier property as a functional polymer. In this case, since oxygen permeation is suppressed, particularly when used for food packaging, the storage stability of food is improved by suppressing deterioration of the content food due to oxygen. For this reason, a multilayer structure of a hydrophobic thermoplastic resin such as polyolefin or polystyrene and a resin having an oxygen barrier property is widely used in a food field or the like where a barrier property against oxygen is required.

[0003] However, these multilayer structures do not have sufficient odor barrier properties, and the odor of the contents leaks outside.
Deterioration of flavor, smell transfer to other things, etc. occur. Therefore, it is desired to impart odor barrier properties to a resin having an oxygen gas barrier property.

As a multilayer structure having excellent odor barrier properties, Japanese Patent Application Laid-Open No. 7-76338 discloses a multilayer packaging material containing a paper base material and a thermoplastic resin. A packaging material for food containers is described in which an odor barrier layer is provided on the inner surface side and a deodorant-containing polyolefin-based resin layer is provided on the opposite side of the paper base material. It is described that an agent may be contained. However, there is no description about stretching a multilayer structure including a resin composition layer composed of a barrier resin and a deodorant.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer structure having excellent oxygen barrier properties and odor barrier properties and excellent transparency.

[0006]

The object of the present invention is to provide a barrier resin (A) of 100 parts by weight and a particle diameter of 0.5 to 10 μm.
A multilayer structure obtained by laminating a thermoplastic resin (D) layer other than the resin (A) on at least one side of a resin composition (C) layer comprising 0.5 to 10 parts by weight of a deodorant (B). And a multilayer structure which is stretched at least twice in the uniaxial direction. Is achieved by providing

In a preferred embodiment, the barrier resin (A) used in the present invention is an ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 60 mol% and a degree of saponification of a vinyl ester component of 85% or more. Polymethaxylylene adipamide.

[0008] In a preferred embodiment, the resin composition (C)
Contains 1 to 25 parts by weight of an inorganic filler (E) having a weight average aspect ratio of 5 or more based on 100 parts by weight of the barrier resin (A) in the resin composition.

In a preferred embodiment, the multilayer structure of the present invention is formed by laminating a thermoplastic resin (D) on both sides of a resin composition (C) layer. The thermoplastic resin (D) used in the present invention is a polyamide resin or a polyolefin resin.

[0010] In a preferred embodiment, the multilayer structure of the present invention is formed by laminating a heat seal layer on at least one surface.

In a preferred embodiment, the multilayer structure of the present invention has a total layer thickness of 5 to 100 μm and a resin composition (C) layer of 2 to 20 μm. The haze of the multilayer structure is 10% or less.

In a preferred embodiment, the multilayer structure of the present invention is used as a multilayer container.

[0013]

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, 10mL ・ 20μm / 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 a polyvinyl alcohol resin or a semi-aromatic polyamide as the barrier resin (A) used in the present invention.

The polyvinyl alcohol-based resin in the present invention 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 90% or more, more preferably 95% or more, and even more preferably 99% or more. 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 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 EVOH used in the present invention
The saponification degree of the vinyl ester component (A) is 90% or more. The saponification degree of the vinyl ester component is preferably 9
5% or more, and optimally 99% or more. If the saponification degree is less than 90%, the gas barrier properties and the 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.

Further, a boron compound may 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, borohydrides, and the like. 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 a 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.

The EVOH used in the present invention contains a phosphorus compound in an amount of 2 to 200 ppm, more preferably 3 to 150 ppm, and most preferably 5 to 100 ppm in terms of phosphorus element.
It is also preferable to include them. Phosphorus concentration in EVOH is 2
If the amount is less than 1 ppm or more than 200 ppm, there may be a problem in melt moldability and thermal stability.
In particular, problems such as the occurrence of gel-like bumps and coloring during long-time melt molding are likely to occur. The kind of the phosphorus compound to be mixed in 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.
An alkali metal salt and an alkaline earth metal salt are preferred. Among them, it is preferable to add a phosphorus compound in the form of sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate and dipotassium hydrogen phosphate, and particularly preferable are sodium dihydrogen phosphate and potassium dihydrogen phosphate. .

Further, 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.

Examples of the semi-aromatic polyamide used in the present invention include polymers of aromatic diamines such as meta-xylylenediamine and para-xylylenediamine and aliphatic dicarboxylic acids such as adipic acid and sebacic acid. An aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, hexamethylene diamine, 2,2,4 and / or 2,4,4-trimethylhexamethylene diamine, octamethylene diamine, decamethylene diamine, dodecamethylene diamine; Polymers with aliphatic or alicyclic diamines such as bis- (4-aminocyclohexyl) methane are exemplified. These semi-aromatic polyamides may be used alone or in combination of two or more.
Among these semi-aromatic polyamides, it is preferable to use a polymer of metaxylylenediamine and adipic acid (polymethaxylylenediamine adipamide) from the viewpoint of gas barrier properties.

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 deodorant (B) used in the present invention refers to a porous active substance which deodorizes odor components by physical adsorption or physical adsorption and chemical adsorption, and a catalyst substance which decomposes odor components by an oxidation-reduction reaction. . Examples of the porous active substance include natural zeolites, synthetic zeolites, silica, activated aluminum oxide, activated aluminum, clay, synthetic clay, and the like. Among them, clay and synthetic clay include activated clay, acid clay, bentonite, and zeolite. And synthetic frypontite-based deodorants.
These are appropriately selected depending on the configuration of the multilayer structure and the odor component, and are used alone or in combination of two or more. Especially when a barrier property against both odor components of acid and base is required,
Synthetic fryponite-based deodorants having both solid acidic and solid basic deodorants are preferred.

The particle size of the deodorizer (B) used in the present invention is 0.5 to 10 μm, more preferably 1 to 8 μm, further preferably 1 to 5 μm, and particularly preferably 1 to 5 μm. ４4 μm. When the particle diameter of the deodorant (B) exceeds 10 μm, the odor barrier properties and the transparency become insufficient. The multilayer structure of the present invention is stretched at least twice in the uniaxial direction. When the deodorant (B) has a particle size of 1 to 4 μm, the stretchability of the multilayer structure before stretching is particularly remarkable. From the viewpoint that the effect of improving odor barrier properties and transparency becomes remarkable. The method for producing such a small particle size deodorant is not particularly limited,
A method in which a commercially available deodorant is pulverized is exemplified as a suitable method.

The particle size of the deodorant (B) in the present invention is determined by taking a photograph of the adsorbent at a magnification of 1000 using an electron microscope, and randomly selecting 20 adsorbents from the photograph. Was used to measure the particle size. This operation was repeated three times, and the average diameter of the adsorbent was determined from a total of 60 measurement results.

The resin composition (C) constituting the multilayer structure of the present invention comprises 100 parts by weight of a barrier resin (A) and 0.5 to 10 parts by weight of a deodorant (B) having a particle diameter of 0.5 to 10 μm. Consists of The amount of the deodorant (B) is more preferably 0.5 to 8 parts by weight, particularly preferably 0.5 to 6 parts by weight, per 100 parts by weight of the barrier resin (A). If the amount of the deodorant (B) is less than 0.5 part by weight with respect to 100 parts by weight of the barrier resin (A), sufficient odor barrier properties cannot be obtained. When the amount of the deodorant (B) exceeds 10 parts by weight with respect to 100 parts by weight of the barrier resin (A), the deodorants (B) are aggregated inside the barrier resin (A). In some cases, and sufficient transparency may not be obtained.

In addition, as long as the object of the present invention is not impaired,
It is optional to blend appropriate amounts of various additives such as a lubricant and a heat stabilizer into the resin composition (C) layer.

In particular, the resin composition (C) comprising 100 parts by weight of the barrier resin (A) and 0.5 to 10 parts by weight of the deodorant (B) is further added with an inorganic filler (E) having a weight average aspect ratio of 5 or more. Is preferably contained in an amount of 1 to 25 parts by weight. By adding such an inorganic filler (E),
The oxygen barrier property and the odor barrier property of the multilayer structure of the present invention can be further improved. The compounding amount of the inorganic filler (E) is more preferably 3 to 15 parts by weight.

The inorganic filler (E) in the present invention
Is a value calculated from the weight average flake diameter l and the weight average flake thickness d of the inorganic filler measured by the following method using the formula (1). α = 1 / d (1) Weight average flake diameter l of the inorganic filler in the formula (1)
Classifies the powder with micro sieves or sieves with various openings, plots the results on a Rosin-Rammlar diagram, and passes the micro sieves or sieves through which 50% by weight of the total weight of the powders used for measurement pass. is a value corresponding to the eyes open l _50. That is, the weight average flake diameter l of the powder
Is defined by equation (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, the portion of the powder having a large particle size is classified by the sieve. The fine part is classified by a micro sieve.
On the other hand, the weight average flake thickness d of the inorganic filler is:
C. E. FIG. Capes et al. Reported a single-particle water surface membrane method {C. E. FIG. Capes and R.A. C. Colema
n. Ind. Eng. Chem. Fundam. , Vo
l. 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 closest packed state on the water surface.

In order to improve the affinity with the barrier resin (A) and prevent perforation at the time of stretching, a surface treatment agent (for example, a silane coupling agent or the like) is applied to the surface of the inorganic filler (E). Is also preferable.

The weight average aspect ratio (α) of the inorganic filler (E) is preferably 5 or more, more preferably 1 or more.
0 or more. If it is less than 5, the effect of imparting oxygen barrier properties and odor barrier properties may be reduced.

Preferred examples of the above-mentioned inorganic filler (E) include, but are not limited to, mica, sericite, glass flake and talc. These inorganic fillers can be used alone or in combination. Among these inorganic fillers, talc is most preferable from the viewpoint of oxygen barrier properties and odor barrier properties.

The method for obtaining the resin composition (C) comprising 100 parts by weight of the barrier resin (A) and 0.5 to 10 parts by weight of the deodorant (B) is not particularly limited. A method in which each component is melt-kneaded by an ordinary melt-kneading apparatus, or a deodorant (B) is added to a solution obtained by dissolving a barrier resin (A) in a solvent.
Examples of suitable methods include a method of mixing, and when the barrier resin (A) is EVOH, a method of adding and mixing a deodorant (B) in a paste state before deposition after saponification. Particularly preferred is a method in which the barrier resin (A) and the deodorant (B) are simultaneously pelletized by a single-screw or twin-screw extruder and dried.

The multilayer structure of the present invention comprises at least one side of a resin composition (C) layer comprising 100 parts by weight of a barrier resin (A) and 0.5 to 10 parts by weight of a deodorant (B).
A multilayer structure obtained by laminating thermoplastic resin (D) layers other than the resin (A) is stretched at least twice in at least one axial direction. Here, it is extremely important to laminate a thermoplastic resin (D) layer on at least one side of the resin composition (C) layer. By stretching such a multilayer structure, it is excellent in oxygen barrier properties and odor barrier properties, In addition, a multilayer structure having excellent transparency can be obtained. On the other hand, as shown in Comparative Example 6, in the case of a single-layer structure composed of only the resin composition (C) having no thermoplastic resin (D) layer, the oxygen barrier property, the odor barrier property and the transparency were improved. The effect cannot be fully exhibited.

The thermoplastic resin (D) other than the barrier resin (A) used in the present invention is not particularly limited, but a polyamide resin or a polyolefin resin is preferred. When a polyamide resin is used as the thermoplastic resin (D), polycapramide (nylon-6) or a copolymer thereof is preferable, and polycapramide (nylon-6) is most preferable, from the viewpoints of transparency and moldability. When a polyolefin resin is used as the thermoplastic resin (D), a polypropylene resin, a polyethylene, a polyvinyl acetate resin, an ionomer resin,
Alternatively, a modified polyolefin obtained by reacting the above-mentioned polyolefin with maleic anhydride or the like by graft polymerization or the like is mentioned as a preferable one.In particular, from the viewpoint of mechanical strength and stretchability of the obtained multilayer structure, it is preferable to use a polypropylene resin. preferable.

From the viewpoint of further improving the odor barrier property, it is preferable to add a deodorant (B) to the thermoplastic resin (D). The compounding amount of the deodorant (B) is preferably 100 parts by weight of the thermoplastic resin (D).
0.5 to 10 parts by weight, and the compounding amount of the deodorant (B) is
The amount is more preferably 0.5 to 8 parts by weight, particularly preferably 0.5 to 6 parts by weight, per 100 parts by weight of the thermoplastic resin (D).

When EVOH or polymeta-xylenediamine adipamide is used as the barrier resin (A), and a polyamide resin, particularly polycapramide (nylon-6) or a copolymer thereof is used as the thermoplastic resin (D) layer. Is capable of exhibiting sufficient interlayer adhesion between the resin composition (C) layer and the thermoplastic resin (D) layer by coextrusion molding, so that stretchability, mechanical strength, oxygen barrier properties and From the viewpoint of odor barrier properties, C / D or D / C / D
Is preferred, and it is particularly preferred to have a D / C / D configuration.

Regarding the layer structure of the multilayer structure of the present invention, an adhesive resin layer may be provided between the resin composition (C) layer and the thermoplastic resin (D) layer. When the resin composition (C) layer is C, the thermoplastic resin (D) layer is D, and the adhesive resin layer is Ad, the layer structure of the multilayer structure of the present invention is C / D, C / Ad / D, D / C / D, D / Ad /
C / Ad / D and the like are exemplified. When a polypropylene resin is used as the thermoplastic resin (D), C / Ad / D
And a configuration of D / Ad / C / Ad / D is preferable, and particularly preferably a configuration of D / Ad / C / Ad / D from the viewpoint of mechanical strength, oxygen barrier properties and odor barrier properties. The multilayer structure of the present invention is characterized in that it is stretched at least twice in the uniaxial direction. When such stretching is performed, a thermoplastic resin (D) layer is provided on both sides of the resin composition (C) layer. By being laminated, it is possible to exhibit excellent oxygen barrier properties and odor barrier properties.

Next, a method for manufacturing the multilayer structure of the present invention will be described. The method for obtaining the multilayer structure before stretching according to the present invention is not particularly limited. Molding methods practiced in the field of general polyolefins, for example, T-die molding, inflation molding, dry laminate molding,
Methods such as extrusion coating and coextrusion molding can be employed. Among them, a method of co-extrusion molding in which each resin is melted by an extruder and discharged and cooled in multiple layers from a round die or a T-die is preferable from the viewpoint that the process can be simplified and the production cost can be suppressed. As described above, EVOH or polymeta-xylenediamine adipamide is used as the barrier resin (A), and a polyamide-based resin, particularly, polycapramide (nylon-6) or a mixture thereof is used as the thermoplastic resin (D) layer. When a polymer is used, it is possible to develop a sufficient interlayer adhesive force between the resin composition (C) layer and the thermoplastic resin (D) layer by co-extrusion molding, and the adhesive resin is interposed. Since there is no need to perform this, the thickness of the multilayer structure can be reduced, and the transparency can be further improved.
From such a viewpoint, it is particularly preferable to perform coextrusion molding. The molding temperature is not particularly limited, and varies depending on the types of the barrier resin (A) and the thermoplastic resin (D).
It is often selected in the range of 70 to 270 ° C.

The multilayer structure of the present invention can be obtained by stretching the multilayer structure obtained by the method exemplified above at least twice in the uniaxial direction. It is essential that the multilayer structure of the present invention is stretched at least twice in the uniaxial direction, and when the stretching ratio is less than twice, the effects of the present invention such as oxygen barrier properties, odor barrier properties, and transparency are obtained. The ability cannot be fully exhibited.

Preferred examples of the method for producing these multilayer structures include, but are not limited to, the following two methods. One method is to form a multilayer structure in which a resin composition (C) layer comprising a barrier resin (A) and a deodorant (B) and a thermoplastic resin (D) layer are simultaneously co-extruded,
This is a method in which biaxial stretching is performed twice or more in the vertical direction and twice or more in the horizontal direction. In another method, at least one layer including a resin composition (C) layer composed of a barrier resin (A) and a deodorant (B) on a thermoplastic resin (D) layer stretched twice or more in a longitudinal direction. Is a method in which a multilayer structure obtained by extrusion coating is stretched twice or more in the lateral direction.

The stretching may be either uniaxial stretching or biaxial stretching, but biaxial stretching is preferred from the viewpoint of improving the transparency, oxygen barrier properties and odor barrier properties of the multilayer structure. In particular, since it is preferable from the viewpoint of the physical properties of the multilayer structure that the resin composition (C) layer is biaxially stretched,
Among the two methods of manufacturing the multilayer structure exemplified above, the resin composition (C) layer comprising the barrier resin (A) and the deodorant (B) and the thermoplastic resin (D) layer are simultaneously co-extruded. It is particularly preferable to biaxially stretch the formed multilayer structure twice or more in the vertical direction and twice or more in the horizontal direction. Suitable stretch ratios vary depending on the composition of the resin composition (C) and the type of the thermoplastic resin (D). Barrier resin (A)
Is made of EVOH, the thermoplastic resin (D) is a polyamide resin, and when the multilayer structure is biaxially stretched, the area magnification is 3 times or more, more preferably 4 times or more, particularly preferably 5 times or more. Stretching is preferred from the viewpoint of improving the transparency, oxygen barrier properties and odor barrier properties. The barrier resin (A) is EVOH, the thermoplastic resin (D) is a polypropylene resin, and the resin composition (C) layer and the thermoplastic resin (D) layer are laminated via an adhesive resin layer. When the multilayer structure is biaxially stretched, the area magnification is 5 times or more, more preferably 10 times or more,
Particularly preferably, stretching by 15 times or more is advantageous for transparency,
It is preferable from the viewpoint of improving the oxygen barrier property and the odor barrier property.

Among them, in the embodiment where transparency is particularly important, the barrier resin (A) used is EVOH.
, A thermoplastic resin (D) and a resin composition (C) made of a polyamide-based resin, and a thermoplastic resin (D) laminated on both sides of the resin composition (C) layer by co-extrusion molding. It is preferable to use a multilayer structure in which the body is stretched at least two times in the uniaxial direction, and an embodiment in which the biaxial stretching is performed four times or more in area ratio is more preferable.

When the stretching ratio of the multilayer structure is less than 2, the transparency, mechanical strength, oxygen barrier property and odor barrier property of the film are not sufficiently exhibited.

As a method of stretching the multilayer structure, a known stretching method can be employed. Double bubble method,
Although there is a method of stretching uniaxially or biaxially by a tenter method, a roll method, or the like, the tenter method is preferable because the film 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. Alternatively, a simultaneous biaxial stretching method using a tenter-type stretching machine that gradually spreads at each clip interval may be used. After stretching the stretched multilayer structure, it is optional to further perform a heat treatment under tension at a temperature not lower than the glass transition point and not higher than the melting point of the thermoplastic resin (D).

The thickness structure of the multilayer structure after stretching is arbitrarily set depending on the use and the like, and is not particularly limited. The total thickness is 5 to 100 μm and the thickness of the resin composition (C) layer Is preferably 2 to 20 μm. If the thickness of the entire multilayer structure is less than 5 μm, there is a possibility that sufficient strength cannot be maintained. When the thickness of the entire multilayer structure is greater than 100 μm, the cost of the multilayer structure increases and the transparency may be deteriorated. Further, the thickness of the resin composition (C) layer is 2 μm.
When the thickness is less than 10 mm, pinholes may easily occur, and when the thickness of the resin composition (C) layer exceeds 20 μm, the cost may increase and the moldability may be unsatisfactory.

From the viewpoint of the mechanical strength, oxygen barrier property and odor barrier property of the multilayer structure, the lower limit of the total layer thickness is 10 μm.
m or more, more preferably 15 μm or more. The lower limit of the thickness of the resin composition (C) layer is preferably 3 μm or more, and particularly preferably 5 μm or more. In applications where transparency is particularly required, the total thickness of the multilayer structure is 80 μm.
It is preferably at most 60 μm, more preferably at most 40 μm, particularly preferably at most 30 μm. Similarly, in applications where transparency is particularly required, the upper limit of the thickness of the resin composition (C) is preferably 15 μm or less, more preferably 10 μm or less. As described above, even when the thickness of the resin composition (C) layer and all layers of the film are reduced in order to emphasize transparency, from the viewpoint that sufficient odor barrier properties and oxygen barrier properties are obtained, The significance is great.

As described above, the multilayer structure of the present invention preferably has a total layer thickness of 5 to 100 μm and a resin composition (C) layer of 2 to 20 μm. In a more preferred embodiment, the haze of such a multilayer structure is preferably 10% or less. When the multilayer structure of the present invention is used for a multilayer packaging container or the like, the haze is particularly preferably 5% or less from the viewpoint of the visibility of the contents.

The application of the multilayer structure obtained in this way differs depending on the thickness of the multilayer structure and the thermoplastic resin used for the outer layer. Since the multilayer structure of the present invention is extremely excellent in transparency, it is preferable to use the multilayer structure of the present invention as a multilayer film or a multilayer container. Examples of the multi-layer container include a multi-layer container formed by molding a multi-layer film comprising the multi-layer structure of the present invention, and a multi-layer bottle formed by biaxially stretch blow-molding a multi-layer parison. From the viewpoint of easiness, it is preferable to prepare a multilayer film and mold the multilayer film as a container. In addition, since the transparency is excellent and the visibility of the contents is good, it is particularly preferable to use the multilayer structure of the present invention as a flexible pouch formed by molding the multilayer film.

Since the multilayer structure of the present invention has a high odor barrier property, it is suitable for use in food packaging containers.
Particularly suitable for use as a flexible pouch for packaging seasonings. In particular, a flexible pouch obtained by molding a multilayer film using a polyamide as the thermoplastic resin (D) has excellent transparency and is therefore suitable for use as a flexible pouch for packaging seasonings.

When the multilayer structure of the present invention is used as a flexible pouch, a heat sealing material such as polyethylene is laminated on both sides or one side of the multilayer film comprising the multilayer structure of the present invention via an adhesive. Preferably, it is used. As such a heat sealing material, a linear low-density polyethylene or polypropylene resin is preferable.

As a method for laminating the heat sealing material, a known dry laminating method or extrusion laminating method can be employed.

The thickness of the heat sealing material is not particularly limited, but is 1 to 1000 μm, preferably 3
３００300 μm, more preferably 5-100 μm, particularly preferably 5-50 μm.

An example in which the multilayer film thus obtained is used mainly as a pouch for packaging seasonings will be described. First, using the film, a pouch is produced using a means such as heat sealing. Next, the contents are filled, and if necessary, the inside is degassed by a known means, or the inside is replaced with an inert gas such as nitrogen gas or carbon dioxide gas, and then sealed by means such as a heat seal.

Examples of the seasoning include, but are not limited to, soy sauce, sauce, vinegar, mirin, dressing, mayonnaise, ketchup, edible oil, miso, lard, somen, soba, udon, and chilled Chinese food.
Among them, it is preferable to package a food containing vinegar, such as vinegar, dressing, mayonnaise, and chilled Chinese soup, since the effects of the present invention are remarkably exhibited.

[0062]

EXAMPLES The present invention will be further described with reference to the following Examples, but it should not be construed that the invention is limited thereto. Various tests in the present invention were performed according to the following methods.

Oxygen Barrier Property A portion of the sample film was cut out, the humidity was adjusted to 20 ° C. and 85% RH, and then oxygen was measured using an oxygen permeation amount measuring device (OX-TRAN-10 / 50A, manufactured by Modern Control). It was evaluated by measuring the amount of permeation (mL / m ² · day · atm).

Odor barrier 10 × 5 cm using a multilayer film obtained by dry laminating a linear low-density polyethylene film having a thickness of 40 μm (hereinafter abbreviated as LLDPE film) on one side.
And make 10g of contents (chilled Chinese sauce)
Filled. The filled pouch was placed in a 100 ml screw tube, and the test sample was stored at 20 ° C.
At each time, the presence or absence of odor leakage was confirmed by the nose of five panelists, and the average value was used for the determination. Good 5>4>3>2> 1 bad

Transparency A part of the sample film was cut out, and the haze value was measured using HR-100 manufactured by Murakami Color Research Laboratory according to ASTM D1003-61.

Impact resistance Linear polyethylene (LLDP) having a thickness of 40 μm on one side
E) A 10 × 5 cm pouch was prepared using a multilayer film obtained by dry laminating the film, and 10 g of the content (cooled Chinese noodles) was filled. 20 ° C-
After sufficient humidity control under the condition of 65% RH, 10 pouches were
The bag was dropped from a height of 1 m on a concrete floor in a room at 0 ° C so that the bag surface and the floor surface were parallel to each other, and the state of damage was visually observed. Good 5>4>3>2> 1 bad

The following Examples are shown in Tables 1 and 2 below.
Was used as a raw material. Here, Table 1 describes the barrier resin (A), and Table 2 describes the deodorant (B).

[0068]

[Table 1]

[0069]

[Table 2]

Example 1 EV having an ethylene content of 32 mol% and a saponification degree of 99.6%
OH (A-1) 100 parts by weight, deodorant (B-1) having a particle diameter of 2.3 μm (prepared by pulverizing “Mizukanite HP” manufactured by Mizusawa Chemical) 5 parts by weight and a talc having a particle diameter of 3 μm (Fuji Talc Co., Ltd., 10 parts by weight of LMS-400) were dry-blended, and then placed in a twin-screw vented extruder and extruded at 220 ° C. to obtain a resin composition (C).

A polyamide resin ("Ube Nylon 1024FDX41" manufactured by Ube Industries, Ltd.) was used as the thermoplastic resin (D). The polyamide resin and the above resin composition (C) were put into separate extruders, respectively, and two or three layers were prepared. Using a co-extrusion apparatus, a film before stretching was prepared by co-extrusion so as to have a configuration of polyamide resin / resin composition (C) / polyamide resin (45/45/45 μm). Extrusion molding is performed using a single screw (40 mmφ) of polyamide resin.
At 50 ° C., the resin composition (C) was mixed with a single screw (40 m
mφ) at 230 ° C. by extrusion.

The resulting two-layer and three-layer film was preheated with hot air for 1 minute, and then stretched in the longitudinal and transverse directions at a stretching temperature of 150 ° C. and a stretching speed of 5 m / min using a pantograph-type biaxial stretching machine. Simultaneous biaxial stretching was performed five times. Here, the stretching temperature refers to a value obtained by measuring the surface temperature of the multilayer structure immediately before stretching after heating the multilayer structure for a predetermined time.

Further, a linear low-density polyethylene film having a thickness of 40 μm (Tocelo TUX-TC # 40, hereinafter sometimes abbreviated to LLDPE film) was dry-laminated on one side of the obtained stretched multilayer film. As an adhesive for dry lamination, Takelac A-385 (manufactured by Takeda Pharmaceutical Co., Ltd.) was used as the main agent, and Takenate A-1 was used.
0 (manufactured by Takeda Pharmaceutical Co., Ltd.) was used as a curing agent.
The application amount of the adhesive was 2.3 g / m ² . After lamination, curing was performed at 40 ° C. for 3 days. The oxygen barrier properties, odor barrier properties, transparency and impact resistance were evaluated using the multilayer films thus obtained. Table 3 shows the results.

Example 2 EV having an ethylene content of 32 mol% and a saponification degree of 99.6%
OH (A-1) 100 parts by weight and particle diameter 2.3 μm
Deodorant (B-1) ("Mizukanite HP" manufactured by Mizusawa Chemical)
After dry blending 5 parts by weight, 2
220 ° C in a screw-type vented extruder
To extrude pellets to obtain a resin composition (C).

100 parts by weight of a polyamide resin (“Ube Nylon 1024FDX41” manufactured by Ube Industries) and 5 parts by weight of a deodorant (B-1) having a particle diameter of 2.3 μm (prepared by crushing “Mizukanite HP” manufactured by Mizusawa Chemical) After dry blending, the mixture was placed in a twin-screw vented extruder and extruded at 220 ° C. to obtain a thermoplastic resin (D). A multilayer film was produced in the same manner as in Example 1 except that the resin composition (C) and the thermoplastic resin (D) prepared above were used, and the multilayer film was evaluated. Table 3 shows the results.

Example 3 EV having an ethylene content of 32 mol% and a saponification degree of 99.6%
OH (A-1) 100 parts by weight and particle diameter 2.3 μm
Deodorant (B-1) ("Mizukanite HP" manufactured by Mizusawa Chemical)
After dry blending 5 parts by weight, 2
220 ° C in a screw-type vented extruder
To extrude pellets to obtain a resin composition (C). A multilayer film was produced in the same manner as in Example 1 except that the resin composition (C) prepared above was used, and the multilayer film was evaluated. Table 3 shows the results.

Examples 4 to 7 The resin composition (C) shown in Table 3 was used in place of the resin composition (C) used in Example 3, and the layer constitution and the stretching ratio were as shown in Table 3. Except for the change, a multilayer film was manufactured in the same manner as in Example 3, and the multilayer film was evaluated. Table 3 shows the results.

Example 8 The resin composition (C) used in Example 3, a polypropylene resin ("Nisso Polypro X4141" manufactured by Chisso) as a thermoplastic resin (D), and a maleic anhydride-modified polypropylene resin as an adhesive resin (Mitsui Chemicals "Admer QF551") is put into separate extruders, respectively, and the thermoplastic resin (D) / adhesive resin / resin composition (C) / adhesiveness is measured using a co-extrusion apparatus of three kinds and five layers. Resin / thermoplastic resin (D) (270/30/150/30/270 μm)
To obtain a multilayer structure before stretching. Extrusion molding is performed using a uniaxial screw (65 mmφ) with a polypropylene resin at 240 ° C, and a maleic anhydride-modified polypropylene resin with a single screw (40 mmφ).
The resin composition (C) was extruded at 210 ° C. using a single screw (40 mmφ) at 240 ° C., respectively.

The obtained multilayer structure was stretched by the following method using a pantograph-type biaxial stretching machine. That is,
After pre-heating the obtained multilayer structure for 1 minute with hot air,
At a stretching temperature of 5 ° C., the film was simultaneously stretched 4.5 times in each of the machine direction and the transverse direction at a stretching speed of 5 m / min. After the completion of the stretching, the multilayer structure was allowed to stand in a stretching machine with tension kept applied for 2 minutes in order to prevent shrinkage of the multilayer structure. The stretching temperature and the heat treatment temperature were measured in the same manner as in Example 1. The obtained multilayer film was evaluated in the same manner as in Example 1. Table 3 shows the results.

Comparative Example 1 Using the same resin composition (C) and thermoplastic resin (D) as used in Example 3, the thermoplastic resin (D) / resin composition (C) / thermoplastic resin (D) was used. ) (7/7/7 μm)
And a three-layer film was prepared and evaluated in the same manner as in Example 1 in a non-stretched state. Table 3 shows the results.

Comparative Example 2 A multilayer film was produced in the same manner as in Example 1 except that only EVOH (A-1) was used as the resin composition (C) and no deodorant was added. The multilayer film was manufactured and evaluated. Table 3 shows the results.

Comparative Example 3 As a deodorant (B), the particle diameter exceeds 10 μm (B-
A multilayer film was produced in the same manner as in Example 3 except that 4) was used. The obtained stretched multilayer film was inferior in the film surface and was unsuitable for practical use, and thus was not evaluated.

Comparative Example 4 A multilayer film was produced in the same manner as in Example 3 except that a resin composition (C) having a deodorant content of more than 10 parts by weight as shown in Table 3 was used. The multilayer film was evaluated. Table 3 shows the results.

Comparative Example 5 The same barrier resin (A), thermoplastic resin (D) and adhesive resin as those used in Example 8 were used. Multilayer film of plastic resin (D) / adhesive resin / resin composition (C) / adhesive resin / thermoplastic resin (D) (10/5/8/5/10 μ)
m) was obtained by coextrusion. Extrusion molding
The polypropylene resin is 240 ° C using a single screw (65 mmφ), and the maleic anhydride-modified polypropylene resin is 240 ° C using a single screw (40 mmφ).
And the resin composition (C) is a single screw (40 mmφ)
At 210 ° C. by extrusion. The obtained multilayer film was evaluated in the same manner as in Example 1. Table 3 shows the evaluation results.

Comparative Example 6 The resin composition (C) used in Example 3 was 20 μm thick.
Using a single-layer film of m, stretching was performed according to the conditions described in Example 1. The obtained single-layer film was evaluated in the same manner as in Example 1. Table 3 shows the evaluation results.

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[Table 3]

[0087]

According to the present invention, it is possible to provide a multilayer structure having excellent oxygen barrier properties and odor barrier properties and excellent transparency. Such a multilayer structure is preferably used as a food packaging container, and particularly preferably as a seasoning packaging flexible pouch.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 101/00 C08L 101/00 F term (Reference) 4F100 AA01A AK01B AK03B AK46B AK47A AK63 AK69A AL05A BA02 BA03 BA10A BA10C BA14 CA23A CA30A CB00 DE01A EH20 EJ37 EJ38 GB16 GB23 JB16B JD02A JD03 JL12C JN01 YY00 YY00A 4J002 AA001 BB221 BE031 CL031 DA096 DE146 DJ006 DJ016 DJ047 DJ057 DL007 FA017 FA037 FA086 FD017 FD206 GG206

Claims (10)

[Claims] 1. A deodorant having a barrier resin (A) of 100 parts by weight and a particle diameter of 0.5 to 10 μm (B) of 0.5 to 10
A multilayer structure obtained by laminating a thermoplastic resin (D) layer other than the resin (A) on at least one side of the resin composition (C) layer composed of parts by weight is stretched at least twice in at least one axial direction. Multilayer structure. 2. The barrier resin (A) having an ethylene content of 5
~ 60 mol%, saponification degree of vinyl ester component is 85%
The multilayer structure according to claim 1, which is the above-mentioned ethylene-vinyl alcohol copolymer or polymethaxylylene adipamide. 3. The resin composition (C) contains 1 to 25 parts by weight of an inorganic filler (E) having a weight average aspect ratio of 5 or more based on 100 parts by weight of the barrier resin (A) in the resin composition. The multilayer structure according to claim 1 or 2, wherein 4. A thermoplastic resin (D) comprising a resin composition (C)
The multilayer structure according to any one of claims 1 to 3, wherein the multilayer structure is laminated on both sides of the layer. 5. The multilayer structure according to claim 1, wherein the thermoplastic resin (D) is a polyamide resin. 6. The multilayer structure according to claim 1, wherein the thermoplastic resin (D) is a polyolefin resin. 7. The multilayer structure according to claim 1, wherein the total thickness of the layer is 5 to 100 μm, and the thickness of the resin composition (C) layer is 2 to 20 μm. 8. The multilayer structure according to claim 7, wherein the haze is 10% or less. 9. A multilayer structure obtained by laminating a heat seal layer on at least one side of the multilayer structure according to claim 1. 10. A multilayer container comprising the multilayer structure according to claim 1.