JPH05104689A - Polyamide-based laminated biaxially stretched film - Google Patents

Abstract

PURPOSE:To provide film, which is excellent in oxygen gas barrier properties, flexural pinholing resistance and toughness and suitable for packaging food, medical supplies, chemicals and the like, by a method wherein the film concerned contains two different layers, with which polyolefins having the melt flow index of specified value or more are mixed by the contents different from one another. CONSTITUTION:The film concerned consists of layer (a), which is made of aromatic polyamide polymer containing 70mol.% or more of polyamide constitutional unit consisting of m- and/or p-xylenediamine and alpha,omega-aliphatic dicarboxylic acid having the number of carbon atoms of 6-12 in molecule chains, and layer (b) made of aliphatic polyamide polymer. Further, the film concerned is a structural body containing at least two different layers including layer (c), which is the mixture of the polymers. In this case, the polyolefins, the melt flow index at 190 deg.C of which is 0.5g/10mm or bore, is mixed in the layer (a) by 0.3-5wt.% and in the layer (c) by 5wt.% or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is excellent in oxygen gas barrier properties, bending pinhole resistance, toughness, etc., and is suitable for a film for packaging foods, medical products, chemicals, etc., which do not want to deteriorate the contents due to oxygen. The present invention relates to a polyamide-based laminated biaxially stretched film.

[0002]

2. Description of the Related Art Heretofore, unstretched films or stretched films of polyamide polymers have been used as various packaging materials, either alone or laminated with other films. However, the commonly used film made of an aliphatic polyamide polymer alone is excellent in mechanical properties such as tensile strength and flex pinhole resistance, but has a drawback that it is not sufficient in oxygen gas barrier property. . Therefore, in order to impart an oxygen gas barrier property to this film, a method of coating a vinylidene chloride polymer latex on the surface of the film to form a film having an excellent oxygen gas barrier property has been proposed and put into practical use. . However, the film coated with this vinylidene chloride-based polymer latex has the drawback that it becomes cloudy when treated with hot water, and when it is incinerated, a compound containing chlorine is generated, which may cause environmental pollution. Was becoming.

On the other hand, as a film having a good oxygen gas barrier property, an aroma mainly containing a polyamide constitutional unit composed of m- and / or p-xylylenediamine and an α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms. A raw material made from a group polyamide polymer has been proposed. This film is excellent in transparency and oil resistance, but is inferior in bending pinhole resistance, so that its use is limited.

In order to obtain a film having the advantages of both of the above polyamide-based polymers, that is, the tensile strength, bending pinhole resistance, and oxygen gas barrier property in combination, two polyamide-based polymers are used. A method for producing a laminated biaxially stretched film by an inflation method by melting and extruding the coalesced separately has been proposed (see JP-A-57-51427). Further, a laminated film having a structure in which a layer containing an aromatic polyamide polymer as a main component is sandwiched between layers containing an aliphatic polyamide polymer as a main component has been proposed (JP-A-56-155762).
(See the official gazette).

However, in the laminated biaxially stretched film proposed in the above-mentioned publication, for example, if the proportion of the aromatic polyamide polymer is increased to improve the oxygen gas barrier property, the laminated film will be resistant to bending pinholes. descend. In addition, in order to improve bending pinhole resistance and toughness,
If the proportion of the aliphatic polyamide polymer is increased, the entire laminated film becomes thicker and cannot be used for flexible packaging, and neither the oxygen gas barrier property nor the flex pinhole resistance is at a satisfactory level.

When a laminated biaxially stretched film is produced by using different kinds of polyamide polymers as raw materials,
The formation of mixtures of different polyamide polymers is unavoidable. For example, from the start of the production of laminated biaxially stretched film until the steady state where products within specifications are obtained, a non-standard film is produced, and even after steady state is reached, ear trimming is performed. There is also a so-called cut scrap. Since these nonstandard films and ear trims are a mixture of different polyamide polymers, it is virtually impossible to separate and collect them separately and use them as virgin raw materials. However, there is a problem that the yield of raw materials decreases and the product cost rises. However, the above publication does not disclose the reuse of these nonstandard films, the ear trim, and the like, and does not disclose measures against deterioration of physical properties when reused.

[0007]

In view of the above situation, the present invention provides a polyamide laminated biaxially stretched film having excellent oxygen gas barrier properties, excellent flex pinhole resistance, toughness and the like. In addition, a nonstandard film produced when a polyamide-based laminated biaxially stretched film, which has been conventionally discarded as scrap, and a mixture of raw polyamide-based polymers such as ear trim are effectively utilized, and It is an object of the present invention to provide a laminated biaxially stretched film in which physical properties are not deteriorated by reusing these.

[0008]

The inventors of the present invention have completed the present invention as a result of intensive studies to solve such problems.

Therefore, the gist of the present invention is that m
-And / or p-xylylenediamine and 6 to 6 carbon atoms
A layer (a) made of an aromatic polyamide polymer (A) containing a polyamide structural unit consisting of 12 α, ω aliphatic dicarboxylic acids in the molecular chain in an amount of 70 mol% or more, and an aliphatic polyamide polymer (B). (B) layer consisting of (c) consisting of a mixture (C) of these polymers (A) and (B)
It is a structure containing at least two types of layers, and is 190 ° C
Melt flow index measured at 0.5g / 10
Polyamide-based biaxially stretched film, characterized in that the polyolefins of min or more are mixed in the layer (a) in an amount of 0.3 to 5% by weight and in the layer (c) in an amount of 5% by weight or less. Exist in.

The present invention will be described in detail below. The main raw materials of the polyamide-based laminated biaxially stretched film according to the present invention are two types of polyamide-based polymers and polyolefins. One type of polyamide-based polymer contains 70% by mole or more of a polyamide constitutional unit composed of m- and / or p-xylylenediamine and an α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the molecular chain. It is a polymer (hereinafter referred to as "polymer (A)").

Specific examples of the polymer (A) include polymeta-xylylene adipamide, poly-meta-xylylene pimeramide, poly-meta-xylylene azeramide, poly-para-xylylene azeramide and poly-para-xylylene decanamide. Homopolymer, metaxylylene / paraxylylene adipamide copolymer, metaxylylene / paraxylylene pimeramide copolymer, metaxylylene / paraxylylene azelamide copolymer, metaxylylene / paraxylylene sepacamide copolymer Copolymers such as coalesced. In addition, a polyamide constituent unit consisting of m- or / and p-xylylenediamine and an α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms is contained in the molecular chain in an amount of 70 mol% or more. Examples thereof include a copolymer composed of a polyamide constituent component.

Other polyamide constituents include diamine components, dicarboxylic acid components and other components. Specific examples of the diamine component include aliphatic diamines such as hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, and heterocyclic rings or heteroatoms such as piperazine bispropylamine and neopentylglycol bispropylamine. There are diamines and the like, and specific examples of the dicarboxylic acid component include aliphatic dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, 1,
There are cycloaliphatic dicarboxylic acids such as 4-cyclohexanedigalvic acid, and other components include lactams such as ε-caprolactam and ω such as ε-aminocarboxylic acid.
-Aminocarboxylic acid, etc.

Further, the polymer (A) may contain a polymer (D) compatible with the polymer (A) up to a range of 20% by weight. Examples of the polymer (D) that is compatible with the polymer (A) include polyamide polymers and other thermoplastic resins not exemplified above. The polymer (A) must have a polyamide constituent unit consisting of m- or / and p-xylylenediamine and an α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the molecular chain in an amount of 70 mol% or more. . When it is out of this range, the target value of the oxygen permeability (temperature 2) to be imparted to the finally obtained laminated biaxially stretched film is obtained.
15cc / m ² · 24H · a at 5 ° C and 65% relative humidity
tm or less), which is not preferable. Further, the polymer (D) when the polymer (D) is contained in the polymer (A)
If the amount exceeds 20% by weight, it is not preferable for the same reason.

Another type of polyamide polymer is an aliphatic polyamide polymer (hereinafter referred to as "polymer (B)"). The polymer (B) may be a chain polyamide having an amide bond, and specific examples thereof include homopolymer of ε-caprolactam, polyhexamethylene adipamide, and ε-caprolactam or hexamethylene. Examples thereof include a copolymer mainly composed of adipamide and 2 to 10 mol% of a compound copolymerizable therewith.

Examples of the compound copolymerizable with ε-caprolactam or hexamethylene adipamide include nylon salts of aliphatic diamines and aliphatic dicarboxylic acids. Specific examples of the aliphatic diamines include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, decamethylenediamine and the like. Specific examples of the aliphatic dicarboxylic acids include adipic acid, sebacic acid, corkic acid, glutaric acid, azelaic acid, β-methyladipic acid, decamethylenedicarboxylic acid, dodecamethylenedicarboxylic acid, pimelic acid and the like.

Among these polymers (B), polyhexamethylene adipamide called nylon 6 or nylon 66, which is a homopolymer of ε-caprolactam, is
It is preferable because it can be obtained at low cost and the biaxial stretching operation can be smoothly performed.

The mixture (C) is a mixture of the polymer (A) and the polymer (B), but it may be a mixture of virgins, or the polyamide-based laminated biaxial of the present invention. It may be a nonstandard film produced when a stretched film is produced, or a scrap mixture such as a cut end material (edge trim) of the film side end, or a scrap mixture to which virgin is added. .. The mixing ratio of these two kinds of polymers is not particularly limited, but it is preferable to select the polymer (A) and the polymer (B) in a weight ratio of 7: 3 to 1: 9. .

The polyamide-based polymer (A), polymer (B) and mixture (C) are all highly hygroscopic, and if they absorb moisture, when the raw materials are heat-melted and extruded, Since water vapor and oligomers are generated and inhibit film formation, it is preferable to dry in advance so that the water content is 0.1% by weight or less. Various additives such as a lubricant, an antistatic agent, an antioxidant, an antiblocking agent, a stabilizer, a dye, a pigment, and inorganic fine particles are added to these polyamide polymers within a range that does not affect the properties of the film. can do.

Polyolefins as main raw materials are homopolymers or copolymers of olefins such as ethylene and propylene, and include, for example, high density polyethylene, low density polyethylene, linear low density polyethylene,
Examples thereof include ethylene-vinyl acetate copolymer and polypropylene. Further, the above polyolefins are uniformly dispersed in the above polyamide resin, but in order to make the dispersion uniform at this time, the melt flow index (MFI) at 190 ° C. is 0.5 g / 10 min or more. is necessary. If the MFI is less than 0.5 g / 10 min, dispersion failure may occur when mixed with a polyamide resin, which is not preferable. In order to disperse the polyolefins in the polyamide resin more uniformly, a suitable compatibilizing agent can be used together. When a compatibilizing agent is used in combination, it is desirable to mix it with polyolefins in advance and pelletize it, but it is not limited to this as long as the dispersibility in the polyamide resin does not change. The three types of layers constituting the polyamide-based laminated biaxially stretched film according to the present invention include (a) layer formed by mixing polyolefins with polymer (A), (b) layer formed of polymer (B), The mixture (C) comprises a layer (c) in which polyolefins are mixed. The layer structure of the polyamide-based laminated biaxially stretched film of the product includes at least two types of layers by appropriately selecting and combining the layers (a), (b), and (c), and the number of layers is three. It is preferable to select in the range of 5 to 5 layers. Specific examples of the combination of layers and the number of layers in this case include (a) / (b) / (c), (b) / (a)
/ (C), (b) / (c) / (a), (c) / (a) /
(C), (b) / (c) / (a) / (b), (b) /
(C) / (a) / (c) / (b), (b) / (a) /
(C) / (a) / (b), (c) / (b) / (a) /
Examples thereof include (b) / (c), but are not limited thereto.

In this case, the mixing ratio of the polyolefins contained in the layer (a) is in the range of 0.3 to 5% by weight based on the total amount of all the polymers contained in the layer (a),
If it is less than 0.3% by weight, there is no effect of improving the bending pinhole resistance of the obtained film, while if it exceeds 5% by weight, the obtained film becomes hazy, which is not preferable. Particularly preferable in the above range is 0.5 to 4% by weight.
Further, in the case where the layer (c) uses an ear trim or the like generated during the production of a laminated film, since the ear trim or the like contains polyolefins, it may not be necessary to newly add polyolefins thereto. However, when the amount of polyolefins contained in the layer (c) is adjusted, it may be newly added. The mixing ratio of the polyolefins contained in the layer (c) is 5% by weight or less based on the total amount of all the polymers contained in the layer (c). It becomes hazy, which is not preferable. Particularly preferred in the above range is 0.1 to 3% by weight.
To mix the polymer (A) constituting the layer (a) and the polyolefin, a method of uniformly dry blending pellets of each polymer so that the above mixing ratio is obtained, and extruding the dry blended product Any method such as melting by a machine and pelletizing may be used.

The polyamide-based laminated biaxially stretched film according to the present invention can be manufactured by a conventionally known general method. First, a polymer mixed with polyolefins (A) and a polymer not mixed with polyolefins (B)
And a raw material composed of a mixture (C) in which polyolefins are mixed to produce a substantially amorphous and unoriented unstretched laminated film. This unstretched laminated film does not require an adhesive for adhering single films to each other, and it is preferable to adopt a co-extrusion method capable of obtaining a laminated film having excellent performance. In the production method by the co-extrusion method, the above raw materials are melted by two or three extruders, extruded from a flat die or an annular die, and then rapidly cooled to obtain a flat or annular unstretched laminated film.

Next, the unstretched laminated film is biaxially stretched 2.5 to 5 times in the film flow (vertical axis) direction and in a direction (horizontal axis) perpendicular thereto. When the stretching ratio is less than 2.5 times in each of the longitudinal and transverse directions of the film, there is no stretching effect and the strength of the film is poor, and when the stretching ratio is greater than 5 times in each axial direction, The film is easily torn during stretching, which is not preferable. As a biaxial stretching method, a conventionally known stretching method such as tenter type sequential biaxial stretching, tenter type simultaneous biaxial stretching, tubular type simultaneous biaxial stretching and the like can be used as long as the gist of the present invention is not exceeded.

For example, in the case of the tenter type sequential biaxial stretching method, the unstretched laminated film is heated to a temperature range of 50 to 110 ° C., and the roll type longitudinal stretching machine makes the longitudinal direction 2.5 to 5 times. Stretching, and then by a tenter type transverse stretching machine within a temperature range of 60 to 120 ° C. in the transverse direction of 2.5 to
It can be produced by stretching it 5 times. On the other hand, in the case of the tenter simultaneous biaxial stretching method or the tubular simultaneous biaxial stretching method, for example, 60 to 110 ° C.
2.5 to 5 in each axial direction in the temperature range
It can be produced by stretching twice.

The film stretched by the above method is then heat treated. By performing the heat treatment, a stretched film having excellent dimensional stability can be obtained. The heat treatment temperature is selected such that the lower limit is 110 ° C. and the upper limit is 5 ° C. lower than the melting point of the polymer (B).
In addition to a stretched film having excellent dimensional stability, a stretched film having an arbitrary heat shrinkage rate can be obtained. The laminated biaxially stretched film, which is sufficiently heat-set by the heat treatment operation, is cooled by a conventional method and wound into a roll.

The polyamide-based laminated biaxially stretched film according to the present invention can be produced by the above method.
Considering the object of the present invention, the following physical properties, that is,
Oxygen transmission rate 25 ° C, relative humidity 65% 1
Number of pinholes after bending 3000 times by Gelvo Flex Tester under conditions of 5 cc / m ² · 24H · atm or less and bending pinhole resistance of 23 ° C and relative humidity of 50% is 15/77 inch. ^When it is ² or less, the oxygen gas barrier property and the bending pinhole resistance are excellent.

The total thickness of the polyamide-based biaxially stretched film according to the present invention is preferably 10 μm or more and 40 μm or less. If the total thickness is less than 10 μ, the oxygen gas barrier property and the flex pinhole resistance are poorly balanced and the abrasion resistance is also poor, so that a satisfactory film for packaging cannot be obtained. On the other hand, when it exceeds 40 μ, the film becomes hard, and when the sealant layer is further laminated, the entire film becomes very thick, which is not suitable for soft packaging.

[0027]

EXAMPLES The contents and effects of the present invention will be described below in more detail with reference to Examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following examples, the film was evaluated by each of the following methods. Table 1 shows the layer structure of the film and the evaluation results.

<Melt Flow Index> JIS K
According to -6760, the melt flow rate of the resin pellet was measured at 190 ° C.

<Oxygen permeability (cc / m ² · 24H · at
m)> Modern control company OXY-TRAN10
It was measured under the conditions of a temperature of 25 ° C. and a relative humidity of 65% using a 0 type oxygen permeability measuring device.

<Bending pinhole resistance (piece / 77 inch
² )> Under conditions of a temperature of 23 ° C. and a relative humidity of 50%, the conditioned film that has been left standing for 24 hours or more is cut into an 8 inch × 11 inch rectangular film, and the rectangular film is a gel manufactured by Rigaku Kogyo Co., Ltd. With the Boflex Tester (No. 901), rotate 440 ° while advancing 3.5 inches, then go straight for 2.5 inches, then
On the contrary, the bending operation test was performed 3000 times with one operation of returning. After the completion of this test, the number of pinholes formed on the tested film was counted.

Example 1 Polymetaxylylene adipamide (MXD-nylon 6121 manufactured by Mitsubishi Gas Chemical Co., Inc.) (polymer (A)) and an ethylene-vinyl acetate copolymer (manufactured by Mitsubishi Yuka Co., Ltd., MITSUBISHI POLYETHI-EVA 25K, melt flow index 3.5 g / 10 min, vinyl acetate content 11 wt%) mixed polymer at a ratio of 97: 3, poly-ε-caproamide (Mitsubishi Kasei Co., Ltd., Novamid 1022) (polymer) (B)), and a crushed material of the edge trim of the film (the mixing ratio of the polymer (A) and the polymer (B) is 40: 6).
0, the mixing ratio of ethylene-vinyl acetate copolymer in the total polymer is 1.2% by weight) is separately melted by using three 65 mmφ extruders and laminated in a co-extrusion T-die. Extruded as a 3-layer laminated film at 30 ° C
The mixture was rapidly cooled by closely adhering to a cast roll of, the outer layer was a polymer (B) of about 54μ, the intermediate layer was a mixture of polymer (A) of about 36μ and ethylene-vinyl acetate copolymer, and the inner layer was a polymer of about 45μ (A). ), A laminated unstretched film comprising a mixture of the polymer (B) and an ethylene-vinyl acetate copolymer. The obtained laminated unstretched film was stretched 3 times in the longitudinal direction by a roll-type stretching machine under the condition of 60 ° C., and then the end portion of this film was held by a tenter clip, and then 90 ° in a tenter oven. After being stretched 3 times in the transverse direction under the condition of ° C, heat treatment was performed at 205 ° C for 6 seconds.

After the heat treatment, the film gripped with clips is cut off from both ears of the film to make scrap, and the product film is wound on a winder to obtain about 6 μm.
Layer of polymer (B) (layer (b)), layer of a mixture of polymer (A) and ethylene-vinyl acetate copolymer of about 4 μ (layer (a)), polymer of about 5 μ (B) A layer of a mixture of the polymer (A) and an ethylene-vinyl acetate copolymer ((c))
Layers) were laminated in this order to obtain a polyamide-based laminated biaxially stretched film having a total thickness of about 15 μm. Table 1 shows the results of measuring the layer structure of the film, the oxygen permeability, and the bending pinhole resistance of the obtained film by the methods described above.

Example 2 In the example described in Example 1, an ethylene-vinyl acetate copolymer was used as a linear low density polyethylene (manufactured by Mitsubishi Kasei Co., Ltd., Mitsubishi Polyethylene LL-FU26, melt flow index 2.0 g / A polyamide laminated biaxially stretched film was obtained by the same method as that described in the same example except that 10 min) was used. Table 1 shows the results of measuring the layer structure of the film, the oxygen permeability, and the bending pinhole resistance of the obtained film by the methods described above.

Example 3 In the example described in Example 1, an ethylene-vinyl acetate copolymer was replaced with an ethylene-acrylic acid copolymer (manufactured by Mitsubishi Petrochemical Co., Ltd., Yucaron EAA XA300M, melt flow index 300 g / 10 min). A polyamide-based laminated biaxially stretched film was obtained by the same method as described in the same example except that Table 1 shows the results of measuring the layer structure of the film, the oxygen permeability, and the bending pinhole resistance of the obtained film by the methods described above.

Example 4 In the example described in Example 1, the ethylene-vinyl acetate copolymer was replaced with a low-density polyethylene (Mitsubishi Kasei Co., Ltd., Mitsubishi Polyethylene LD L261, melt flow index 7 g / 10 min). In the same manner as described in Example 1, a polyamide laminated biaxially stretched film was obtained. Table 1 shows the results of measuring the layer structure of the film, the oxygen permeability, and the bending pinhole resistance of the obtained film by the methods described above.

Examples 5 to 9 In the examples described in Example 1, except that the layer constitution, film thickness, composition ratio of raw materials, and mixing ratio of polyolefins were changed as shown in Table 1, respectively, A polyamide laminated biaxially stretched film was obtained by the same method as described in the same example. Table 1 shows the results of measuring the layer structure of the film, the oxygen permeability, and the bending pinhole resistance of the obtained film by the methods described above.

Comparative Example 1 A polyamide-based biaxially stretched film was obtained in the same manner as in Example 1 except that polyolefins were not used. Table 1 shows the results of measuring the layer structure of the film, the oxygen permeability, and the bending pinhole resistance of the obtained film by the methods described above.

Comparative Example 2 In the example described in Example 1, an ethylene-vinyl acetate copolymer was prepared from polyethylene (Mitsubishi Kasei Co., Ltd., Mitsubishi Polyethylene HD ES300, melt flow index 0.
However, a good product could not be obtained although an attempt was made to prepare a polyamide-based biaxially stretched film by the same method as that described in the same example except that the amount was changed to 05 g / 10 min).

Comparative Example 3 A commercially available vinylidene chloride-coated biaxially stretched nylon film (manufactured by Mitsubishi Kasei Polytech Co., Ltd., Santonyl SG, thickness 17 μ) was used, and the oxygen gas barrier property and bending resistance pin were obtained by the above-mentioned method. The results of measuring the hole property are shown in Table 1.

[0040]

[Table 1]

In Table 1, each abbreviation has the following meaning. A: Polymer (A) B: Polymer (B) EVA: Ethylene-vinyl acetate copolymer LLDPE: Linear low density polyethylene EAA: Ethylene-acrylic acid copolymer LD: Low density polyethylene HD: Polyethylene PO: Polyolefin table 1, the polyamide-based laminated biaxially stretched film according to the present invention had measured values of oxygen gas barrier property, bending pinhole resistance, etc. within the intended numerical range, and particularly, had excellent bending pinhole resistance. Therefore, it can be seen that the film of Comparative Example is within the target numerical value for the oxygen gas barrier property, but the flexural pinhole resistance is outside the target numerical value range.

[0042]

INDUSTRIAL APPLICABILITY The present invention has particularly remarkable effects as follows, and its industrial utility value is extremely large. 1. The polyamide-based laminated biaxially stretched film according to the present invention has excellent oxygen gas barrier properties, excellent bending pinhole resistance, and toughness. Therefore, it is suitable for a film for packaging foods, medical products, medicines, etc., which do not like the deterioration of the contents due to oxygen. 2. Further, the polyamide-based laminated biaxially stretched film according to the present invention can efficiently collect and reuse scraps such as ear trim materials and can be effectively utilized industrially.

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Claims (1)

[Claims] 1. An aromatic polyamide polymer containing, in its molecular chain, 70% by mole or more of a polyamide constitutional unit composed of m- and / or p-xylylenediamine and an α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms. Composed of (A) (a)
A layer, a layer (b) composed of an aliphatic polyamide polymer (B),
The polymer (A) and the polymer (B) have a structure including at least two layers of a layer (c) made of a mixture (C), and have a melt flow index measured at 190 ° C. of 0.5 g / 10 min. The above polyolefins are
0.3-5 wt% for layer (a), 5 wt% for layer (c)
Hereinafter, a polyamide-based laminated biaxially stretched film, characterized by being mixed with each other.