JPH085164B2 - Flexible gas barrier laminated packaging container with excellent bending fatigue resistance - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible laminated packaging material which does not deteriorate in gas barrier property even under extremely severe bending fatigue. Specifically, it is a flexible laminated packaging material having a thin film made of a saponified ethylene-vinyl acetate copolymer (hereinafter referred to as EVOH) having a gas barrier property against oxygen, carbon dioxide gas and the like as an intermediate layer. The heat of fusion based on the thermal analysis of the differential scanning calorimeter is 2 in any of the surface layers.
By using a linear low-density polyethylene layer of 5 cal / g or less, an airtight package of an easily-deteriorated article packaged with the packaging material is subjected to extremely severe bending fatigue when the package is transported or handled. (EN) Provided is a laminated flexible packaging container which can maintain excellent gas barrier property and is effective for preventing alteration of a packaged object.

[0002]

2. Description of the Related Art The function of a flexible laminated packaging material is basically storage stability of a packaged article, that is, prevention of alteration, and therefore, the packaging material has, in particular, transport vibration strength and bending fatigue resistance. when used as the inner container - but is required, inter alia, so-called bag-in-box - thin inner container of foldable plastic and stackability, lifting Chi carry of a container combining the outer cardboard box having printability Require a high degree of this property. The packaging material is used by laminating various plastic films by taking advantage of the characteristics of each material. For example, a combination of a base material film for maintaining mechanical strength and a heat sealable material is the most common. Therefore, the material is selected according to the request of the object to be packaged. In particular, for unsatisfactory uses of the base film for blocking gas such as oxygen, a barrier layer having a higher gas blocking property is provided on the base layer, and the barrier layer can be heat-sealed as an intermediate layer. A method of laminating a thermoplastic resin layer so that the material is at least one outer layer is adopted. For example, the basic material of the inner container of the conventional bag-in-box is that there is always a heat-sealable part, so heat-sealable polyethylene, especially soft polyethylene, is mainly used, but the characteristic feature of the bag-in-box is that it can be folded. In view of the fact that the content is a liquid, physical strength, transport vibration strength, and bending fatigue resistance are required as described above, which is combined with good stress crack resistance. An ethylene-vinyl acetate copolymer resin is more preferably used.

In the case where gas barrier properties such as oxygen are required as the required performance becomes higher, nylon film,
The inner container in which a Saran-coated nylon film, an aluminum-deposited nylon film, an aluminum-deposited polyester film and the like are combined has begun to be put into practical use. In order to impart a high gas barrier property, a saponified product of an ethylene-vinyl acetate copolymer , polyvinylidene chloride, an aluminum foil, a vapor deposited film of metal or the like is used. However, although these have excellent gas barrier properties, they generally have low mechanical strength and cannot withstand bending fatigue. Therefore, it is used by being laminated between a base material layer having excellent mechanical strength and a heat-sealable material. However, when it is used as a constituent material of a bag-in-box container, pinholes are generated in the constituent material. , Even at the stage where no pinholes are formed in the constituent material, due to cracks and pinholes etc. occurring in the barrier layer used as the intermediate layer, the deterioration of the barrier property, etc. It has not been found to be practically satisfactory because it cannot maintain an excellent gas barrier property.

A layer mainly composed of polyvinylidene chloride resin,
The behavior of a laminated packaging material having a barrier layer of a vapor-deposited resin layer of aluminum foil or metal is described in, for example, JP-A-55-55.
No. 7477. That is, actually using the packaging material, transportation of the packaged package, the gas barrier property after handling is not always satisfactory, and the most necessary practical preservation after primary distribution is often betrayed. , Due to damage to the barrier layer located in the intermediate layer. EVOH resin is the most excellent material for the intermediate layer provided to improve gas barrier properties, and is preferably used as a barrier material for various multilayer films and containers having a multilayer structure.

These resins not only have excellent gas barrier properties, but also have excellent transparency, oil resistance, printability, moldability, etc., and are extremely advantageous in that they do not impair the characteristics of the base resin. This is because it has properties. However, there is no example in which EVOH resin is satisfactorily used as a barrier layer of a laminated packaging material in a field where flex fatigue resistance is particularly required. Above all, it is strongly demanded to withstand bending fatigue due to transportation vibration as described above. EVOH resin is used for the inner container of a bag-in box having a property of blocking gas such as oxygen, and no one satisfying the requirement has been found.
Development of a flexible laminated packaging material having excellent barrier properties using the EVOH layer as a barrier layer and flexural fatigue strength to withstand transport vibration was one of the important issues.

Further, Japanese Utility Model Publication No. 47-23353 discloses that
A description is given of a laminated packaging material in which EVOH is used as an intermediate layer and high pressure low density polyethylene (branched low density polyethylene) is provided in the inner and outer layers. Such a laminated packaging material is as shown in Comparative Example 1 described later. Flex fatigue resistance is extremely poor. Further, Japanese Patent Laid-Open No. 55-12008 describes a packaging material in which EVOH is laminated on linear low-density polyethylene, but a packaging material having such a structure is also shown in Comparative Example 2 described later. Flex fatigue resistance is not yet sufficient.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
While the film has the above-mentioned various excellent properties, polyethylene, polypropylene, nylon, as compared with a film of a thermoplastic resin such as thermoplastic polyester, not only has a major drawback of being significantly inferior in bending fatigue resistance,
EVO is used as an intermediate layer by laminating with a resin layer resistant to bending fatigue.
Unexpectedly, in a multi-layer flexible packaging material using an H resin layer, it seems to be related to physical properties such as rigidity of EVOH, but the bending fatigue resistance of the packaging material is thermoplasticity that is strong against the bending fatigue. The resin is significantly lower than the bending fatigue resistance shown by itself, and pinholes are formed in the laminated packaging material with less bending fatigue. Even more surprisingly, the EVOH layer is formed until the pinholes are generated. Is considered to be caused by the fact that cracks and pinholes due to bending fatigue do not occur in the EVOH layer even if it exceeds the bending fatigue that can withstand by itself. It was found that the behavior of a conventional laminated packaging material using a vinylidene resin or the like as a barrier layer in the intermediate layer is remarkably different, and from this viewpoint, the EVOH layer as a barrier layer is resistant to bending. And we have completed the present invention to promote an extensive study relates superior flexible gas barrier laminated packaging containers labor.

[0008]

The present invention provides a laminated packaging material comprising an EVOH thin film as an intermediate layer and surface layers on both sides of the intermediate layer, each layer being provided with an adhesive resin layer interposed therebetween. Any of the surface layers can be used for thermal analysis of a differential scanning calorimeter.
It is intended to provide a flexible gas barrier laminated packaging container excellent in bending fatigue resistance, characterized by comprising a linear low-density polyethylene layer having a heat of fusion of 25 cal / g or less .

The bending fatigue resistance is determined by various materials or various materials from data such as the bending number dependency of the gas barrier property deterioration in the evaluation test performed using a so-called gelbo flex tester, the bending number of times until the pinhole is generated, and the like. It is possible to judge the superiority or inferiority of the bending fatigue resistance of the laminated packaging material made of the material. The inventors of the present invention used a Gelbo flex tester for a single-layer film of various thermoplastic resins and a laminated film of various resins, and used a gelbo flex tester to show the relationship between the number of times of bending and the number of pinholes, the number of times of bending to generate pinholes, and As for the laminate having a multi-layered structure, several facts were found as a result of variously measuring the relationship between the number of times of bending and the barrier property (for example, the amount of oxygen permeation) in the process leading to the occurrence of pinholes.

That is, (1) all EVOH resin films have extremely poor flexural fatigue resistance, which is far below the level of transportation vibration strength that can be practically used. (2) Conventional high pressure method The film of each resin such as low density polyethylene, low pressure high density polyethylene, nylon, polypropylene, thermoplastic polyester is EVO.
Although the flex fatigue resistance is remarkably superior to that of the H resin film, the flex fatigue resistance of the laminate film in which the resin film is laminated with EVOH as an intermediate layer is not clear in detail, but an EVOH layer is present. Due to the remarkable decrease, that is, a remarkable decrease compared to the excellent flex fatigue resistance of the resin single film,
(3) Surprisingly, almost no deterioration in gas barrier property was observed until the occurrence of pinholes in the laminate having the EVOH layer as an intermediate layer. (4) Above all, both surface layers Has a heat of fusion of 25 ca based on the thermal analysis of a differential scanning calorimeter.
It was found that the laminate using the linear low-density polyethylene layer having a ratio of 1 / g or less has a remarkable improvement in bending fatigue resistance.

Heat of fusion based on thermal analysis of differential scanning calorimeter
The improvement in flexural fatigue resistance is remarkable only in the case where the linear low-density polyethylene having a viscosity of 25 cal / g or less is used for any of the surface layers in the laminate having the constitution in which EVOH is the intermediate layer. Further, although the details of the phenomenon are not yet clear, the effect of the improvement is revealed in the heat of fusion based on the thermal analysis of the linear low density polyethylene differential scanning calorimeter.
In addition, it is deeply involved in the carbon number and Young's modulus of the α-olefin which is a copolymerization component, and it is particularly remarkable when linear low density polyethylene in these selected specific regions is adopted. Is.

The linear low-density polyethylene used in the present invention is a linear low-density polyethylene having substantially no long-chain branch. Generally, a quantitative measure of the number of long chain branches G = [η] b / [η] l ([η] b is the intrinsic viscosity of branched polyethylene, [η] l is a linear polyethylene having the same molecular weight as branched polyethylene) Has an intrinsic viscosity of about 1 (generally in the range of 0.9 to 1 and often close to 1) and a density of 0.910 to 0.945.
(The G value of the conventional ordinary high-pressure low-density polyethylene is 0.1 to 0.6.) The method for producing linear low-density polyethylene is not particularly limited.

A typical manufacturing method is 7 to 45 k.
pressure of g / cm ² (typically 2000~3000kg / cm ² in the case of high-pressure low-density polyethylene), 75-100
Temperature of ℃ (120 ~ for high density low density polyethylene)
250 ° C.) using a chromium-based catalyst or Ziegler catalyst, an α-olefin having 3 or more, preferably 4 or more, more preferably 5 to 10 carbon atoms, such as propylene, butene-1, methylpentene-1, hexene-1. , Octene-1, etc. as a copolymerization component, there is a method of copolymerizing ethylene. As the polymerization method, a solution method liquid phase method, a slurry method liquid phase method, a fluidized bed gas phase method, a stirred bed gas phase method and the like are used.

As described above, the effects of the present invention, the carbon number of the α-olefin, the heat of fusion of the linear low-density polyethylene by the thermal analysis of the differential scanning calorimeter, and the Young's modulus are deeply concerned. However, more specifically, it is as follows. That is, the linear chain used in the present invention
Low density polyethylene has a heat of fusion of 25 cal / g or less
belongs to. When the heat of fusion exceeds 25 cal / g
Shows that the bending fatigue resistance is not sufficient as shown in Comparative Example 3.
It was. Such linear low density polyethylene has a heat of fusion
Is preferably 25-5 cal / g, or 20
Young's modulus at 0 ° C is 2 kg / mm ² or less, preferably 22 to 3 kg / mm ² , and more preferably 22 to 5 kg.
The effect of the present invention is more remarkable with respect to the polyethylene having the ratio of 1 / mm ² , particularly, when both are in the above range.

Although the heat of fusion and Young's modulus in the above range are slightly different depending on the polymerization method and the polymerization conditions, generally, the content of the α-olefin as a copolymerization component is about 2 mol% or more, preferably It is often obtained in the range of about 2 to 7 mol%. For the linear low-density polyethylene whose copolymerization component is butene-1, the heat of fusion is 15 cal / g or less, or the Young's modulus at 20 ° C. is 12 kg.
The effect of the present invention is more prominent when the ratio is / mm ² or less, and the effect can be most remarkably exerted when the both are in the above-mentioned region. The low-density polyethylene having the heat of fusion and Young's modulus in the above-mentioned range is generally obtained in a range where the content of butene-1 is about 4 mol% or more. If the content is too large, the other physical properties of the polyethylene will be unsatisfactory, which is not preferable, and the content is preferably at most several mol%, for example, 7 mol%.

Further, the effects of the present invention can be enjoyed for the linear low-density polyethylene having the heat of fusion and / or Young's modulus in the above-mentioned specific region as described above.
As described above, for example, the effect can be more remarkably applied to the polyethylene containing 5 to 10 α-olefin as a copolymerization component. In this case, for the same reason as described above, the content of the α-olefin is preferably 2 to 7 mol%, more specifically 2 to 6 mol%, and the heat of fusion is as described above. In particular, the heat of fusion is preferably 25 to 5 cal / g, and the Young's modulus is 22 kg / mm ² or less, preferably 22 to 3
kg / mm ^2, more preferably from 22~5kg / mm ^2. Among these olefins, the linear low-density polyethylene containing 4-methyl-1-pentene as a copolymerization component, which is more advantageous in the effect of the present invention and is easily obtained industrially, is one of the most preferable ones. . In the case of the conventional high-pressure low-density polyethylene, the effect of the present invention cannot be obtained even if the heat of fusion and / or Young's modulus by the thermal analysis of the differential scanning calorimeter are within the above range.

Despite the extremely poor pinhole resistance of the EVOH single film, the linear low-density polyethylene of the present invention is used for any surface layer, and a laminated film having an EVOH layer as an intermediate layer is used. A stage in which cracks or pinholes naturally occur in the intermediate layer and the barrier property of the laminated packaging material is expected to be deteriorated, judging from the point that the pinhole resistance is remarkably improved, that is, in view of the characteristics of the EVOH single film. In the above, the point that the barrier property of the laminated packaging material is not recognized is extremely specific unlike the conventional laminated packaging material using the barrier material such as vinylidene chloride.

Regarding the melt viscosity of the linear low-density polyethylene, particularly when the laminated material is obtained by a coextrusion method, the melt viscosity is relatively similar from the viewpoint of melt viscosity matching with EVOH resin and the like. Is preferably selected and used. This linear low-density polyethylene has a melt index (MI) of 19 according to ASTM D-1238-65T.
The value measured under the condition of 0 ° C. and 2160 g load) is 0.1
It is -20 g / 10 minutes, preferably 0.2-10 g / 10 minutes.

In the laminated packaging material of the present invention, if the surface layer made of the linear low-density polyethylene is too thin, for example, when each layer reaches 10 μm or less, other physical properties are deteriorated. It is preferably at least 20 μm, more preferably at least 20 μm. Further, if the thickness is increased too much, the effect of the present invention is diminished, so it is more preferable to use each surface layer of 60 μm or less. In particular, the composition of the container in the back-in-box is usually 25-60μ
Can be suitably used by selecting it from the thickness region (thickness of each surface layer) according to the internal capacity.

The laminated wrapping material of the present invention is required to have each layer arranged through an adhesive resin layer, and causes delamination during a bending fatigue resistance test by the Gelbo Flex Tester. It shouldn't be.
When the delamination is caused, the effect of improving the bending fatigue resistance of the EVOH layer located in the intermediate layer by the lamination is not recognized, and the phenomenon of deterioration of the barrier property due to the damage of the EVOH layer causes a pinhole in the lamination film. The effect of the present invention cannot be enjoyed because it has already been recognized at a stage where the occurrence of is not recognized.

The adhesive resin used in the present invention is not particularly limited as long as it does not cause the delamination at a practical stage, but if it is strongly said, an adhesive resin rich in flexibility is more preferable, Particularly, in combination with the linear low-density polyethylene layer and the adhesion to the EVOH layer, a carboxyl group-containing modified product of an ethylene-vinyl acetate copolymer and a carboxyl group-containing modification of an ethylene-acrylic acid ethyl ester copolymer The thing is preferable. It is particularly preferred that the carboxyl group-containing modified product is a maleic anhydride modified product. In addition, ethylene-vinyl acetate copolymer is at least 8
It is more preferable that the vinyl acetate content is at least wt%.

The EVOH resin used in the present invention preferably has an ethylene content of 20 to 60 mol%, preferably 25 to 60 mol%, and a saponification degree of 95% or more. When the ethylene content is 20 mol% or less, further 25 mol% or less, it is considered that not only the moldability is lowered but also the rigidity of the EVOH is increased, but the effect of the present invention is diminished, and When the ethylene content exceeds 60 mol%, the rigidity decreases, but the gas barrier property against oxygen and the like, which is the most characteristic of the resin, decreases and the resin becomes unsatisfactory. The EVOH resin is 20 to 60 mol%, preferably 25 to 6
Even if a blend of two or more resins having different ethylene contents having an ethylene content within the range of 0 mol% is within the range showing compatibility, the effects of the present invention are enjoyed. can do. The saponification degree of the resin is 95%
The above is preferable, and if it is less than 95%, the barrier property is deteriorated, which is not preferable. Furthermore, EVOH treated with a boron compound such as boric acid and a third component such as a silicon-containing olefinically unsaturated monomer are copolymerized with ethylene and vinyl acetate, and modified EVOH obtained by saponification is also melt-moldable. The effects of the present invention can be enjoyed as long as the degree of modification does not impair the properties. This EVOH melt index (MI) (ASTMD
The value measured by -1238-65T at 190 ° C. under a load of 2160 g) is 0.1 to 25 g / 10 minutes, preferably 0.3 to 20 g / 10 minutes.

As described above, in the case of the EVOH single layer, the flexural fatigue resistance is extremely poor and shows a slight improvement tendency as the thickness decreases, which satisfies the practically required transport vibration strength. It is only a phenomenon in a region far below the level of flex fatigue resistance. However, in the constitution of the laminated packaging material of the present invention, the peculiarity of the EVOH existing as an intermediate layer to the layer thickness dependence on the number of times of bending of the Gelbo flex tester, which causes pinholes due to bending fatigue, is extremely remarkable. Sex is recognized. The EVO
If the thickness of the H layer exceeds 20μ, the bending fatigue resistance decreases,
This is not preferable because the effects of the present invention are diminished. In order to fully enjoy the effects of the present invention, the EVOH layer has a thickness of 20.
It is preferably μ or less, and more preferably 15 μ or less. From the viewpoint of only flex fatigue resistance, 10 μm or less is most preferable.

However, when there is a higher requirement for the gas barrier property against oxygen or the like, the requirement often cannot be satisfied with a thickness of the intermediate layer of 20 μm or less. The most preferred embodiment of the present invention satisfying higher requirements regarding flex fatigue resistance and the barrier property is that the thickness of the EVOH layer is selected to be 20μ or less, preferably 15μ or less, more preferably 10μ or less. The EVOH layer is provided in a plurality of two or more in accordance with the degree of high requirement for the barrier property. From the viewpoint of resistance to bending fatigue, it is preferable that the thickness of the EVOH layer is as small as possible, but the difficulty in terms of molding technology increases accordingly. Practically, it is preferably 2 μm or more, and 5 μm or more is more preferable from the viewpoint of being relatively difficult. Below 2μ, pinholes often occur in the EVOH layer,
The yield of non-defective products decreases.

In providing a plurality of the barrier layers, EVOH having the same ethylene content may be used for all of the layers, and when the relative humidity inside the container is larger than the relative humidity outside the container, For example, when the material to be packaged is an aqueous mixture such as wine, the positional relationship between the layers of the plurality of barrier layers is such that the EVOH layer having a smaller ethylene content is arranged on the outside in relation to the humidity dependency of the barrier property of EVOH. However, it is more preferable to dispose an EVOH layer having a larger ethylene content on the inner side, and when the relationship of the relative humidity is reverse, it is preferable to dispose the positional relationship of the EVOH layer in reverse. The optimum configuration can be selected according to the purpose. In this case, it is preferable that at least two layers of the barrier layers are composed of EVOH having different ethylene contents of 5 mol% or more in order to obtain the effect of adopting the constitution.

The laminated packaging material used in the present invention can be obtained by a known method such as a co-extrusion method, an extrusion lamination method, a dry lamination method, and a container using the laminated packaging material, for example, a container in a bag-in-box is laminated. After obtaining a film having a constitution by a known method, it is heat-sealed, a film-sealing method in which a mouth portion is attached, and a die having a laminated constitution formed according to the shape of the product, which is preliminarily formed into a film, and then a die. Is a vacuum molding method to physically fix the, multi-layer melt extrusion molding multi-layer varison consisting of the material of the present invention is sandwiched by a mold with a die inserted, and is molded with compressed air. It can be obtained by a known method such as a blow molding method in which the main body and the die are heat-bonded by pressure.

In the present invention, EVOH is used as an intermediate layer, and a layered material having linear low-density polyethylene layers on both sides thereof may be provided with another layer (resin layer or the like).
It is free as long as the object of the invention is not impaired. The thus obtained laminated packaging material of the present invention is suitable as a container material for carrying foods, particularly liquid foods, for example, alcohols such as wine and sake, and soy sauce.

[0028]

The present invention will be further described with reference to the following examples, but the present invention is not limited thereto. Example 1 Ethylene content 31 mol%, Saponification degree 99.4%, MI
2. A 12 μm-thick intermediate layer made of EVOH resin of 1.3 g / 10 min, and 4-methyl-1-pentene having a thickness of 35 μm on both sides of the intermediate layer as a copolymerization component, and the copolymerization component was added to 3.
Containing 2 mol%, MI 2.1 g / 10 min, heat of fusion by differential scanning calorimeter {based on ASTM D3417-75
And measured by the method described in ASTM (9.7).
Value} is 19 cal / g and has a surface layer made of linear low-density polyethylene (hereinafter referred to as LLDPE), the thickness of vinyl acetate content of 5 μm is 33% by weight, and the degree of modification with maleic anhydride is 1.5. A laminated film having an MI of 1.5% by weight of a modified ethylene-vinyl acetate copolymer and having an MI of 1.5 g / 10 min. Was laminated through an adhesive resin layer using three extruders and a three-layer five-layer multilayer die head. Obtained by the extrusion method. A bending fatigue test was performed on the obtained laminated film until generation of pinholes was observed in the laminated film, and the oxygen gas permeation amount at each stage until the generation of the pinholes was measured.

In the bending fatigue test, a gelbo flex tester (manufactured by Rigaku Kogyo Co., Ltd.) was used to make a 12 in.times.8 in sample piece into a cylindrical shape with a diameter of 3 l / 2 in, and both ends were gripped. Gripping interval when bending 1i
n, the first 3l / 2 in of the stroke, a twist of 440 ° C was applied, and the subsequent 2l / 2 in repeated linear horizontal motion, and reciprocating motion at a speed of 40 times / min.
It is carried out under conditions of ° C and relative humidity of 65%.

The oxygen gas permeation amount is measured by Modern.
Using OX-TRAN100 manufactured by Control, 2
65% at 0 ° C relative humidity (denoted as RH) and 80% at 20 ° C
It was measured by RH. The sample after the bending fatigue test at each stage was formed into a 12 in x 8 in plane, and the measurement was made at the center thereof. The Young's modulus was measured according to ASTM D-882-67 at 20 ° C. and 65% relative humidity. Table 1 shows the measurement results. There was almost no change in the oxygen permeation amount during the bending fatigue test process until the occurrence of pinholes. No pinholes were observed until the flex fatigue test was repeated 4000 times, and after 4050 cycles, it was confirmed that one pinhole had already been generated at the time of inspecting the presence or absence of pinholes. Moreover, delamination between the layers was not observed at all. The LLDPE film was separately obtained, and the Young's modulus was measured at 20 ° C. The result was 13 kg / mm ² .

[0031]

[Table 1]

Example 2 EV having ethylene content of 45 mol% and saponification degree of 99.2%
The intermediate layer is OH resin, and the thickness of the surface layer (LLDPE) disposed on both sides of the intermediate layer is 40 μm for one side and 3 μm for the other side.
The same procedure was performed as in Example 1 except that the value was 0 μ. No pinholes were observed until the bending fatigue test was repeated 4500 times, and two pinholes were observed after 4600 cycles. Table 2 shows the measured values of the oxygen permeation amount. No delamination between layers was observed.

[0033]

[Table 2]

Example 3 A laminated film having a constitution of D / Ad / E / Ad / F / Ad / G was obtained by using a coextrusion equipment having a multilayer die head for 3 kinds of 7 layers. Each layer is composed of each resin and layer thickness shown below. Ad: vinyl acetate content 35% by weight, maleic anhydride modification degree 1.0% by weight, MI 1.8 g / 10
Minute thickness consisting of modified ethylene-vinyl acetate copolymer 5
μ Adhesive resin layer D, G: MI containing 4.0 mol% of 4-methyl-1-pentene as a copolymerization component 2.3 g / 10 min, heat of fusion 15 cal / g by differential scanning calorimeter 38μ L
LDPE layer E, F: ethylene content 38 mol%, saponification degree 99.4
%, MI 1.6 g / 10 min, EVOH resin layer having a thickness of 6 μ A bending fatigue test was conducted in accordance with Example 1. Generation of pinholes was not recognized even after 5000 cycles of the bending fatigue test. Table 3 shows the measured values of the oxygen permeation amount at each stage up to the 5000 reciprocations. No delamination between layers was observed. The Young's modulus of the LLDPE film separately obtained and measured at 20 ° C. was 7.5 kg / mm ² .

[0035]

[Table 3]

Example 4 E is a layer of the same EVOH resin as in Example 1 with a thickness of 8 μ, and F is the same EVOH resin as in Example 2 with a thickness of 6 μ.
The same procedure as in Example 3 was carried out except that the above layer was used. Generation of pinholes was not recognized even after 5000 cycles of the bending fatigue test. Table 4 shows the measured values of the oxygen permeation amount at each stage up to the 5000 round trips. No delamination between the layers was observed.

[0037]

[Table 4]

Example 5 In Example 1, the EVOH resin layer had a thickness of 19μ, the adhesive resin had a thickness of 19μ, and the adhesive resin had a thickness of 7μ and contained 25% by weight of ethyl acrylate and maleic anhydride. Example 1 except that a modified ethylene-acrylic acid ethyl ester copolymer having an acid modification degree of 1.7% by weight was used.
It was carried out according to. No pinhole was observed until the bending fatigue test was repeated 3600 times. 40
Generation of three pinholes was observed after the time of 00 round trips. 40
Table 5 shows the oxygen permeation amount at each stage of the bending fatigue test up to 00 reciprocations. No delamination between the layers was observed.

[0039]

[Table 5]

Example 6 In Example 1, 1-heptene was used as a copolymerization component in both surface layers, the content was 2.9 mol%, the heat of fusion by a differential scanning calorimeter was 20 cal / g, and the temperature was 20 ° C. The same procedure as in Example 1 was performed except that LLDPE having a measured Young's modulus of 15 kg / mm ² was used. Generation of pinholes was not recognized even after the bending fatigue test of 3500 reciprocations, and the value of oxygen permeation value was almost unchanged, being approximately 1.4 cc / m ² , 24 h.
r (20 ° C., 80% RH).

Example 7 In Example 1, butene-1 was used as a copolymerization component, the content of the component was 5.1 mol%, the heat of fusion by a differential scanning calorimeter was 12 cal / g, and the Young's modulus measured at 20 ° C. Is 8 kg
Example 1 was repeated except that both surface layers were made of LLDPE of / mm ² . Generation of pinholes was not observed even after passing through 4000 cycles of the bending fatigue test, and there was almost no change in the value of oxygen permeation, which was 1.5 cc / m ² , 2
It was 4 hr (20 ° C., 80% RH).

Example 8 Example 7 was repeated except that LLDPE having a butene-1 content of 3.6 mol%, a heat of fusion by a differential scanning calorimeter of 19 cal / g and a Young's modulus of 16 kg / mm ² was used. The same procedure as in Example 7 was performed. No pinhole was found after 850 cycles of the bending fatigue test, but the occurrence of pinholes was observed after 900 cycles of the cycle. The oxygen permeation value did not change at all until the pinhole was generated.

Comparative Example 1 The same procedure as in Example 1 was carried out except that both surface layers were formed using various conventional high-pressure low-density polyethylene. In the bending fatigue test, the number of reciprocations required until the occurrence of pinholes was 200 at most.

Comparative Example 2 Using the same material as in Example 3, F (15μ) / Ad (7
μ) / G (40 μ) was obtained by using a coextrusion equipment having a multi-layer die head for three kinds of three layers. As a result of performing a bending fatigue test (using a Gelbo flex tester) according to Example 1, the number of reciprocations until the occurrence of pinholes was recognized was 250 at most.

Comparative Example 3 In Example 1, butene-1 content was 1.9 mol%,
The heat of fusion measured by a differential scanning calorimeter is 32 cal / g,
Except for using LLDPE with a loading rate of 27 kg / mm ^2.
The same procedure as in Example 1 was performed. Bending fatigue test according to Example 1
As a result of performing (by Gelbo flex tester),
The number of round trips to confirm the occurrence of pinhole is at most 30
It was 0 times.

Example 9 The laminated packaging materials obtained in Examples 1 to 8 and Comparative Examples 1 and 2 were heat-sealed and further fitted with a mouthpiece to obtain a packaging bag. 1 kg of liquid food was put in this packaging bag, and the mouthpiece part of the bag was sealed. Each of the 20 sealed bags was packed in a cardboard box to form a back-in box. After conditioning this back-in-box at 20 ° C.-60% RH for 2 days, it was subjected to a rotary vibration tester (vibration condition 267).
r. p. Vibration test was performed according to m). The results are shown in Table 6.

[0047]

[Table 6]

[0048]

EFFECTS OF THE INVENTION Excellent flex fatigue resistance, flexibility, and excellent gas barrier properties.

Claims (8)

[Claims] 1. A thin film of a saponified product of an ethylene-vinyl acetate copolymer is used as an intermediate layer, and surface layers are provided on both sides of the intermediate layer.
In a laminated packaging material in which each of the layers is arranged via an adhesive resin layer, all of the surface layers are heat of a differential scanning calorimeter.
A flexible gas barrier laminated packaging container excellent in bending fatigue resistance, characterized by comprising a linear low-density polyethylene layer having a heat of fusion of 25 cal / g or less based on analysis . 2. The laminated packaging container according to claim 1, wherein the linear low-density polyethylene has an α-olefin having 4 or more carbon atoms as a copolymerization component. 3. The linear low-density polyethylene is butene-1.
2. The laminated packaging container according to claim 1, wherein the heat of fusion is 15 cal / g or less as determined by the thermal analysis of the differential scanning calorimeter. 4. The method of claim 1 Young's modulus at 20 ° C. of linear low density polyethylene is 22 kg / mm ² or less or
Or the laminated packaging container according to any one of 2 . 5. The linear low-density polyethylene is butene-1.
As a copolymerization component, Young's modulus at 20 ° C is 12 kg
/ Mm ² or less, the laminated packaging container according to claim 1 or 3 . 6. linear low density polyethylene is one which the copolymer component of 5 or more α- olefins having a carbon number claim 1 or 4 laminated packaging container according. 7. The linear low-density polyethylene has 4-methyl-1-pentene as a copolymerization component.
The laminated packaging container described. 8. A thickness of the intermediate layer is 5～20Myu, laminated packaging container according to any one of claims 1-7 thickness of each layer of the surface layer is 25～60Myu.