JPH05193081A - Polyamide base laminated biaxially stretched film - Google Patents

Abstract

PURPOSE:To obtain a method for utilizing effectively raw material resins in providing a film excellent in oxygen barrier properties, bending pinhole resistance and toughness and suitable for soft packing of food, medicines and chemicals. CONSTITUTION:A polyamide base laminated biaxially stretched film is composed of a structure consisting of at least two kinds of layers selected from three layers composed of a mixture of aromatic polyamide and an ionomer resin, aliphatic polyamide and a mixture of two kinds of polyamides and an ionomer resin.

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, a polyamide-based unstretched film or stretched film has been used in various general packaging applications alone or as a laminate with another film. However, a film made of an aliphatic polyamide is excellent in mechanical properties such as tensile strength and resistance to bending pinholes, but is not sufficient in oxygen gas barrier property. Therefore, a vinylidene chloride-based resin coat film in which a vinylidene chloride-based polymer latex is coated on the surface of this aliphatic polyamide film to impart an oxygen gas barrier property has been proposed and put into practical use. However, the above vinylidene chloride polymer resin coat film has a drawback that its application is extremely limited because it becomes cloudy when subjected to hot water treatment, and further, when incinerated, a compound containing chlorine is generated. Therefore, it has been a cause of environmental pollution.

On the other hand, as a film having a good oxygen gas barrier property, there has been proposed a film made from an aromatic polyamide polymer containing a polyamide constitutional unit composed of xylylenediamine and an aliphatic dicarboxylic acid as a main component. 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 the above aliphatic polyamide film and aromatic polyamide film, that is, tensile strength, bending pinhole resistance, and oxygen gas barrier property.
A method for producing a laminated biaxially stretched film by an inflation method by melt-extruding these two types of polyamides (see Japanese Patent Application Laid-Open No. 57-51427) or an aromatic polyamide between layers containing an aliphatic polyamide as a main component. A laminated film having a layer structure in which a layer containing a polyamide as a main component is arranged (Japanese Patent Laid-Open No. Sho 5).
No. 6-155762) is also proposed.

However, in the laminated biaxially stretched film proposed in the above publication, the bending pinhole resistance and the toughness are improved by the contribution of the layer made of the aliphatic polyamide, and the contribution of the layer made of the aromatic polyamide is made. Although this tends to improve the oxygen gas barrier property, it does not have both the flexing pinhole resistance and the oxygen gas barrier property at a satisfactory level. Further, in the case of producing a coextruded laminated film using different kinds of polyamides as raw materials, it is inevitable to generate a mixture of different polyamide resins. For example, from the start of operation of the laminated biaxially stretched film manufacturing equipment, until reaching the steady state where the product within the standard is obtained, a non-standard film is formed, or even after reaching the steady state,
There is also a cut end piece called ear trim. Since it is virtually impossible to separately collect individual polyamides from these nonstandard films and cut ends, it is necessary to dispose of them as a polyamide resin mixture or reuse them for some purpose. In this case, when these resin mixtures are discarded, the raw material yield is reduced, the economic efficiency is impaired, and the disposal itself is costly. From this viewpoint, in the production of this laminated film, effective utilization of the resin mixture generated has been strongly desired. However, even in the above publication, no attention is paid to the reuse of these nonstandard films, cut scraps, and the like.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is a polyamide-based laminated biaxially stretched film having both toughness, excellent oxygen gas barrier properties, and excellent bending pinhole resistance. In addition, a laminated biaxially stretched film that can be produced by effectively utilizing a raw material polyamide mixture that is generated as a nonstandard film or a cut waste material when producing a polyamide laminated biaxially stretched film is provided. To do.

[0006]

The inventors of the present invention have completed the present invention as a result of intensive studies to solve such problems. The gist of the present invention is, therefore, a layer (a) made of the following polyamide (A) and / or a layer (b) made of the following polyamide (B).
A layered film comprising a layer and a layer (c) composed of a mixed composition (C) of the polyamide (A) and the polyamide (B), wherein the polyamide (A) constituting the layer (a) is an ionomer described below. 0.3 to 10% by weight of the resin mixture,
The mixed composition (C) constituting the layer (c) is a polyamide-based laminated biaxially stretched film characterized by containing an ionomer resin mixture in an amount of 10% by weight or less. Polyamide (A): 70 mol% of a polyamide constitutional unit consisting of m- and / or p-xylylenediamine and an α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the molecular chain.
Aromatic Polyamide Containing Polyamide (B): Aliphatic Polyamide Ionomer Resin Mixture: Ethylene / Acrylic Acid Copolymer Containing Acrylic Acid and / or Methacrylic Acid Content of 10 to 20% by Weight, Ethylene / Methacrylic Acid Copolymer 20 to 40% of the carboxyl groups of the polymer or ethylene / acrylic acid / methacrylic acid copolymer are neutralized, and the melt flow rate at 190 ° C. and a load of 2160 g is 0.5 to 10 g / 10 minutes or less. A mixture of 70% by weight or more of an ethylene copolymer (ionomer resin) and 30% by weight or less of another thermoplastic resin.

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 polyamide (A), polyamide (B), and an ionomer resin mixture. Specific examples of the polyamide (A) defined above include polymetaxylylene adipamide, polymetaxylylene pimeramide, polymetaxylylene azamide, polyparaxylylene azamide, and polyparaxylylene decanamide. Homopolymer, metaxylylene / paraxylylene adipamide copolymer, metaxylylene / paraxylylene pimeramide copolymer, metaxylylene / paraxylylene azelamide copolymer, metaxylylene / paraxylylene sepacamide copolymer Copolymers such as coalesced. In addition, m- or / and p
As long as a polyamide constituent unit consisting of 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, a copolymerization weight of this component and another polyamide constituent component It may be a united body.

Examples of the other polyamide constituent components include nylon salts of diamines and dicarboxylic acids, lactams such as ε-caprolactam, and ω-aminocarboxylic acids such as ε-aminocarboxylic acid. Specific examples of diamines as a component of the nylon salt include aliphatic diamines such as hexamethylenediamine and 2,2,4-trimethylhexamethylenediamine, and different diamines such as piperazine bispropylamine and neopentylglycol bispropylamine. There are nodal or heteroatom-containing diamines, and specific examples of dicarboxylic acids include adipic acid, azelaic acid, aliphatic dicarboxylic acids such as sebacic acid, terephthalic acid, aromatic dicarboxylic acids such as isophthalic acid, Examples thereof include cycloaliphatic dicarboxylic acids such as 1,4-cyclohexanedigalvonic acid. If the polyamide (A) is in the range of 20% by weight or less,
It is also possible to use it by adding another thermoplastic resin (D) having compatibility therewith. Examples of the other thermoplastic resin (D) compatible with the polyamide (A) include polyamides and other thermoplastic resins not exemplified above.

The polyamide (A) contains 70 mol% or more of a polyamide constitutional unit composed of m- or / and p-xylylenediamine and an α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the molecular chain. Must be one.
As the polyamide (A), when the proportion of the specific polyamide constituent unit in the molecular chain is less than 70 mol%, the oxygen gas barrier property to be imparted to the finally obtained laminated biaxially stretched film is a target value. (Temperature 25
15cc / m ² · 24H · at under ℃ and 65% relative humidity
m or less), which is not preferable. Further, if the content of the other thermoplastic resin (D) above 20% by weight is used as the polyamide (A), the oxygen gas barrier property similarly does not reach the target value, which is not preferable.

The polyamide (B) defined above is a so-called aliphatic polyamide. Specific examples thereof include lactam polymers such as poly-ε-caprolactam, aliphatic polyamides composed of aliphatic diamines and aliphatic dicarboxylic acids such as polyhexamethylene adipamide, polymers of ω-aminocarboxylic acids, and ε Examples of the copolymer include caprolactam or hexamethylene adipamide as a main component, and a copolymer of 2 to 10 mol% of a compound copolymerizable therewith. For example, when the polyamide (B) is a copolyamide having ε-caprolactam as a main component, examples thereof include nylon salts of aliphatic diamines and aliphatic dicarboxylic acids, and hexamethylene adipamide as a main component. In the case of the copolyamide, the copolymerizable compound includes lactams such as ε-caprolactam. Specific examples of the aliphatic diamines constituting the nylon salt used for copolymerization include ethylenediamine,
Examples thereof include 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. Examples thereof include methyl adipic acid, decamethylene dicarboxylic acid, dodecamethylene dicarboxylic acid and pimelic acid. Among these polyamides (B), homopolymers of ε-caprolactam called nylon-6 or polyhexamethylene adipamide called nylon-66 are available at low cost and can be biaxially stretched. Is preferable because it can be carried out smoothly.

The mixed composition (C) is a homogeneous mixture of the polyamide (A) and the polyamide (B).
The mixed composition (C) may be a mixture of the raw material polyamide (A) and the raw material polyamide (B),
In addition, when the polyamide-based laminated biaxially stretched film of the present invention is manufactured, a raw material polyamide mixture generated as a nonstandard film or a cut end material (edge trim) or a raw material polyamide mixture generated is prepared by adding the raw material polyamide. It may be. The composition (mixing ratio) is not particularly limited, but it is preferable to select the polyamide (A) and the polyamide (B) in a weight ratio of 7: 3 to 1: 9.

The polyamide (A), the polyamide (B) and the mixed composition (C) are all highly hygroscopic, and if moisture-absorbed materials are used, steam and oligomers are generated when the raw material is melted by heat and extruded. Since it inhibits film formation, it is preferably dried in advance to have a water content of 0.1% by weight or less. Various additives such as lubricants, antistatic agents, antioxidants, antiblocking agents, stabilizers, dyes, pigments, and inorganic fine particles are added to these raw material polyamides and polyamide mixed compositions within a range that does not affect the properties of the film. Can be added.

The ionomer resin mixture in the present invention means an ethylene / acrylic acid copolymer, an ethylene / methacrylic acid copolymer, or an ethylene / methacrylic acid having an acrylic acid and / or methacrylic acid content of 10 to 20% by weight. 20-40% of the carboxyl groups of acrylic acid / acrylic acid copolymer are neutralized, 190 ° C, 2160g
Melt flow rate under load 0.5 to 10g / 1
A polymer containing at least 70% by weight of an ethylene-based copolymer (ionomer resin) for 0 minutes. The acrylic acid and / or methacrylic acid content of the ionomer resin needs to be 10 to 20% by weight, and more preferably 12 to 18% by weight. 10
If it is less than 10% by weight, the dispersibility of the ionomer resin mixture in the polyamide resin is deteriorated, and the obtained film becomes hazy, which is not preferable. On the other hand, when it is more than 20% by weight, the dispersibility of the ionomer resin mixture in the polyamide resin is too high, the particle size of the dispersed ionomer resin becomes small, and the effect of improving the bending pinhole resistance of the obtained film is rather decreased. Further, the cost of the ionomer resin also increases, which is not preferable.

The degree of neutralization of the carboxyl groups of the ethylene / methacrylic acid copolymer, the ethylene / acrylic acid copolymer, or the ethylene / methacrylic acid / acrylic acid copolymer is 20 to 40%, preferably 25 to 35. % Is preferable. When the degree of neutralization is less than 20%, the dispersibility of the ionomer resin mixture in the polyamide resin decreases, and the obtained film becomes hazy, which is not preferable. On the other hand, when it exceeds 40%, the fluidity of the ionomer resin mixture at the time of melting is deteriorated, and the obtained film is also hazy, which is not preferable. Zinc, sodium, lithium, potassium, magnesium, calcium and the like are often used as the neutralizing metal component. In particular, zinc and sodium are preferably used, but not limited thereto. The melt flow rate of the ionomer resin mixture used is 190
0.5-10 g / 10 minutes at a temperature of 2160 g,
More preferably, it should be 1 to 8 g / 10 minutes. When the melt flow rate is less than 0.5 g / 10 minutes, the fluidity of the ionomer resin mixture at the time of melting is low, and the obtained film becomes hazy, which is not preferable. If the melt flow rate is larger than 10 g / 10 minutes, the ionomer resin mixture is not finely dispersed in the polyamide resin, and the flexural pinhole resistance of the obtained film is deteriorated, which is not preferable.

The ionomer resin mixture is used as the ionomer resin itself or as a mixture of the ionomer resin and the thermoplastic resin (E) in an amount of 30% by weight or less. As the thermoplastic resin (E), those generally referred to as polyolefins can be used, and examples thereof include low density polyethylene, linear low density polyethylene, high density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer. A polymer, an ethylene-ethyl methacrylate copolymer, a resin mixture of these, or the like can be used.
The melt flow rate of the thermoplastic resin (E) is preferably 0.5 to 10 g / 10 minutes at 190 ° C. and a load of 2160 g, similarly to that of the ionomer resin. When the melt flow rate is less than 0.5 g / 10 minutes, the flowability of the ionomer resin mixture at the time of melting is low, and the obtained film is apt to become hazy, which is not preferable. The melt flow rate of the thermoplastic resin (E) is preferably close to the melt flow rate of the ionomer resin to be mixed, but is not limited to this as long as the dispersibility of the ionomer resin mixture in the polyamide resin does not change. .. The ratio of the thermoplastic resin (E) in the ionomer resin mixture is 3
If it exceeds 0% by weight, the dispersibility of the ionomer resin mixture in the polyamide resin decreases, and the obtained biaxially stretched laminated film becomes hazy, which is not preferable. To mix the resins, it is desirable that the ionomer resin and the thermoplastic resin (E) are melt-kneaded in an extruder and pelletized before use, but if the dispersibility of the ionomer resin mixture in the polyamide resin does not change, It is not limited.

The polyamide-based laminated biaxially stretched film according to the present invention comprises the above-mentioned polyamide (A) (a) layer and / or polyamide (B) (b) layer, and polyamide (A) and polyamide (B). Polyamide (A), which is composed of the layer (c) of the mixed composition (C) and which constitutes the layer (a), contains the ionomer resin mixture in an amount of 0.3 to 10% by weight, preferably 0.1. The mixed composition (C) containing 5 to 5% by weight and constituting the layer (c) is characterized in that it contains the above ionomer resin mixture in an amount of 10% by weight or less, preferably 0.1 to less than 5% by weight. .. The following examples can be given as typical layer configurations, but the present invention is not limited to these. (1) Example of two-layer structure (a) / (c), (b) / (c) (2) Example of three-layer structure (a) / (b) / (c), (b) / (a) / (C),
(B) / (c) / (a), (c) / (a) / (c) (3) Example of 4-layer structure (b) / (c) / (a) / (b) (4) 5 Example of layer structure (b) / (c) / (a) / (c) / (b), (b) /
(A) / (c) / (a) / (b), (c) / (b) /
(A) / (b) / (c)

In the polyamide-based laminated biaxially stretched film according to the present invention, the polyamide (A) constituting the layer (a).
When the ionomer resin mixture content of is less than 0.5% by weight, the effect of improving the bending pinhole resistance is small,
This is because if it is less than 0.3% by weight, its effect is further reduced and the target value of the bending pinhole resistance (the number of pinholes is 15/77 inch ² or less by the evaluation method described later) cannot be achieved, while the ionomer is used. Resin mixture content is 5
When the content exceeds 10% by weight, the effect of improving the resistance to bending pinholes tends to approach saturation, and at the same time, the laminated film obtained tends to become hazy and the appearance is impaired. Because it appears in. Further, the ionomer resin mixture content of the mixed composition (C) constituting the layer (c) is also 10% by weight or less, preferably 0.1 to less than 5% by weight for the same reason. As the mixed composition (C) constituting the layer (c), when a nonstandard film or a cut end material (ear trim) generated during the production of a laminated film is recycled,
Since the ionomer resin mixture in the layer (a) or the layer (c) is naturally recycled, it may not be necessary to positively add the ionomer resin mixture.

The polyamide (A) containing a predetermined amount of the ionomer resin mixture is obtained by dry blending the polyamide (A) and the ionomer resin mixture in a predetermined ratio, or by melting the dry blended product in an extruder and pelletizing. Any of these may be used. Further, the mixed composition (C) containing a predetermined amount of the ionomer resin mixture can be prepared in the same manner.

The polyamide-based laminated biaxially stretched film according to the present invention can be manufactured by a conventionally known general method. First, a polyamide (A) and / or a polyamide (B) containing an ionomer resin mixture, and a mixed composition (C) containing a predetermined amount of an ionomer resin mixture are used as raw materials and aligned in a substantially amorphous form. It is better to manufacture a non-laminated film (hereinafter referred to as "laminated unstretched film") by a coextrusion method.

This laminated unstretched film is produced by melting the above-mentioned raw materials with a couple of extruders, extruding from a flat die or an annular die, and then rapidly cooling it to form a flat or annular laminated unstretched film. It is preferable to adopt the coextrusion method using a film. Next, the above-mentioned laminated unstretched film is biaxially stretched in the range of 2.5 to 5 times in the film flow direction (longitudinal direction) and in the direction perpendicular thereto (horizontal direction), respectively. When the stretching ratios in the longitudinal and transverse biaxial stretching directions are each less than 2.5 times, the effect of stretching is small, the film strength is poor, and the stretching ratio in the biaxial stretching direction is 5 times or more. When it is large, the laminated film is likely to tear or break during stretching. Therefore, the upper limit of the stretching ratio is preferably within the above range. As a biaxial stretching method, conventionally known stretching methods such as tenter type sequential biaxial stretching, tenter type simultaneous biaxial stretching, and tubular type simultaneous biaxial stretching can be adopted as long as they do not exceed the gist of the present invention.

For example, in the case of the tenter type sequential biaxial stretching method, the laminated unstretched film is heated to a temperature range of 50 to 110 ° C., and a roll type longitudinal stretching machine is used to form 2.5 in the longitudinal direction.
~ 5 times, then 6 by a tenter type horizontal drawing machine
It can be produced by stretching the film in the transverse direction in the temperature range of 0 to 120 ° C. by 2.5 to 5 times. In the case of a tenter simultaneous biaxial stretching method or a tubular simultaneous biaxial stretching method, for example, in the temperature range of 60 to 110 ° C,
It can be manufactured by stretching in the longitudinal and transverse directions at a time 2.5 to 5 times in each axial direction. The laminated biaxially stretched film stretched by the above method is subsequently heat treated. By heat treatment, dimensional stability at room temperature can be imparted. In this case, the heat treatment temperature is preferably selected within a range of 110 ° C. as a lower limit and 5 ° C. lower than the melting point of polyamide (B) as an upper limit. It is possible to obtain a stretched film that has. The laminated biaxially stretched film, which is sufficiently heat-set by the heat treatment operation, is cooled and wound by a conventional method.

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 permeability is 15cc / m ² · 24H · atm or less under the condition of temperature 25 ° C and relative humidity 65%, and temperature 2
If the number of pinholes after repeated bending for 3000 cycles by the Gelbo flex tester under the conditions of 3 ° C. and 50% relative humidity is 15/77 inch ² or less, the oxygen gas barrier property and the flexing pinhole resistance are excellent. .. The total thickness of the polyamide-based laminated biaxially stretched film according to the present invention is preferably 10 μm or more and 40 μm or less. The overall thickness is
If it is less than 10 μm, the oxygen gas barrier property and the flex pinhole resistance are poorly balanced, and the abrasion resistance is insufficient, so that a satisfactory film for packaging cannot be obtained. Also, 40
If it exceeds μ, the film becomes hard, and when a sealant layer is further laminated, the entire film becomes very thick, which makes it unsuitable for soft packaging. Further, the polyamide-based laminated biaxially stretched film of the present invention can be produced by laminating a sealant layer into a bag shape.

[0023]

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 laminated film obtained was evaluated by the following method. Table 1 shows the ionomer resin components, and Table 2 shows the layer structure and evaluation results of the laminated film. <MFR> Load of 2160 g according to JISK-6760,
The measurement was performed at a measurement temperature of 190 ° C. <Oxygen Transmission Rate (cc / m ² · 24H · atm)> Oxy-TRAN100 type oxygen transmission rate measuring device manufactured by Modern Control Co. was used and measured under the conditions of temperature 25 ° C and relative humidity 65%.

<Bending pinhole resistance (piece / 77 inch
² )> A film cut into a size of 8 inches x 11 inches is left standing for 24 hours or more under the condition of a temperature of 23 ° C and a relative humidity of 50% to be conditioned, and a Gelbo flex tester (manufactured by Rigaku Kogyo, No. .901 (based on the standard of MIL-B-131C)), the bending test was repeated as follows, and the pin pole was measured. The rectangular test film is formed into a cylindrical shape having a length of 8 inches, one end of the cylindrical film is fixed to the outer circumference of the disk-shaped fixed head of the tester, and the other end is fixed to the outer circumference of the tester disk-shaped movable head. In the direction of the fixed head, a rotation of 440 ° was made while making 3.5 inches closer to each other along the axes of the two heads facing each other in parallel, and then straight movement was carried out for 2.5 inches without being rotated. The bending test, which was performed in the opposite direction and in which the process for returning the movable head to the initial position was one cycle, was continuously repeated for 3000 cycles. A pinhole tester (made by Sanko Denshi Kenkyusho, TR
A voltage of 1 KV was applied by a D-type), and the number of pinholes generated in the film was measured by a bending test and evaluated. <Transparency> When the film was attached to the sample chamber of a transparency measuring machine (TM-1D type, manufactured by Murakami Color Research Laboratory) and rotated 360 ° about the optical axis, the transmittance of light having a wavelength of 546 ± 5 nm was measured. The average of the maximum value and the minimum value was taken as the transparency of the measurement film.

Example 1 Polymethaxylylene adipamide (MX-nylon 6007 manufactured by Mitsubishi Gas Chemical Co., Inc.) (polyamide (A)) having a relative viscosity of 2.7 and the ionomer resin 1 shown in Table 1 were used. : Poly (epsilon-caproamide) having a relative viscosity of 3.7 (Mitsubishi Kasei Co., Ltd.)
Manufactured by Novamid 1022) (polyamide (B)), and the edge trim end material (polyamide (A) and polyamide (B) produced from another film manufacturing test (proportion (weight) of 40:60) occupy the whole. (Ionomer resin 1 content is 1.2% by weight) are separately melted using three 65 mmφ extruders, laminated in a coextrusion T-die and extruded as a laminated film having a three-layer structure, 30 ° C
The mixture was rapidly cooled by closely adhering to a cast roll of No. 5, and the outer layer was about 54μ of polyamide (B), the intermediate layer was about 36μ of polyamide (A) and a mixed composition of ionomer resin 1, and the inner layer was about 4μ.
An unstretched laminated film consisting of 5 μm of each of the ear trim end material composition was obtained.

The unstretched laminated film thus obtained was stretched 3 times in the machine direction in a roll type stretching machine under the conditions of 60 ° C., and then the end portion of this lengthwise stretched film was held by a tenter clip, and then in a tenter oven. Horizontally 3 at 90 ° C
After stretching twice, it was heat-treated at 205 ° C. for 6 seconds.
After the heat treatment, the both ends of the film, which correspond to the grips of the clip, are trimmed, and the trimmed product film is wound into a roll, and the outer layer is about 6μ, the intermediate layer is about 4μ, and the inner layer is about 4μ. 5 μ, (b) /
(A) / (c) three-layer structure, the total thickness is about 15μ
A laminated biaxially stretched film of was obtained. The oxygen permeability of the obtained film was measured by the above-mentioned method, and the bending pinhole resistance and the transparency were evaluated. The results are shown in Table 2 below together with the layer structure of the film and the like.

Examples 2 to 8, 10 and 11 In the example described in Example 1, the type of ionomer resin, the content ratio of the ionomer resin, the layer constitution and the resin composition of each layer are as shown in Table 2 below. A laminated biaxially stretched film was obtained by the same method as described in the same example except that it was replaced. With respect to the obtained film, the oxygen transmission rate was measured in the same manner as in the same example, and the bending pinhole resistance and the transparency were evaluated. The results are shown in Table 2 below together with the layer structure of the film and the like.

Example 9 In the example described in Example 1, the ionomer resin 1 used in the same example was added to the ionomer resin 3 with 20 wt% of ethylene-vinyl acetate copolymer (25K manufactured by Mitsubishi Petrochemical Co., Ltd.) and mixed, A laminated biaxially stretched film was obtained by the same method as described in the same example except that the extrusion pelletized ionomer resin 8 was replaced. With respect to the obtained film, the oxygen transmission rate was measured in the same manner as in the same example, and the bending pinhole resistance and the transparency were evaluated. The results are shown in Table 2 below together with the layer structure of the film and the like.

Comparative Example 1 A laminated biaxially stretched film was obtained by the same method as described in Example 1 except that the ionomer resin was not used in the example described in Example 1. With respect to the obtained film, the oxygen transmission rate was measured in the same manner as in the same example, and the bending pinhole resistance and the transparency were evaluated. The results are shown in Table 2 below together with the layer structure of the film and the like.

Comparative Examples 2 to 4 A laminated biaxially stretched film was prepared in the same manner as in Example 1 except that the type of ionomer resin was changed as shown in Table 2 in the example described in Example 1. Got
With respect to the obtained film, the oxygen transmission rate was measured in the same manner as in the same example, and the bending pinhole resistance and the transparency were evaluated. The results are shown in Table 2 below together with the layer structure of the film and the like.

Comparative Example 5 Using a commercially available vinylidene chloride-coated biaxially stretched nylon film having a thickness of 17 μ (manufactured by Mitsubishi Kasei Polytech Co., Ltd., Santonil SG), the oxygen transmission rate was measured, and the bending pinhole resistance and the transparency were measured. evaluated. The results are shown in Table 2 below.

[0032]

[Table 1]

[0033]

[Table 2]

In Tables 1 and 2, each abbreviation has the following meaning. MFR: Melt flow rate EVA: Ethylene-vinyl acetate copolymer A: Polyamide (A) B: Polyamide (B) K-ONY: Vinylidene chloride coated biaxially stretched nylon film

From Table 2, the laminated biaxially stretched film according to the present invention has an oxygen gas barrier property and a bending pinhole resistance within the intended numerical ranges, and in particular, is excellent in the bending pinhole resistance. It can be seen that the film of the example has the oxygen gas barrier property within the target numerical value, but the bending pinhole resistance is outside the target numerical value range.

[0036]

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 flexure pinhole resistance, and toughness, and the like, and also foods that dislike the alteration of contents by oxygen, medical products, It is suitable for a film for packaging medicines and the like. 2. Further, the polyamide-based laminated biaxially stretched film according to the present invention can efficiently collect and utilize scraps such as ear trim materials, and can be effectively utilized industrially.

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Claims (1)

[Claims] 1. A (a) comprising the following polyamide (A):
Layer and / or layer (b) comprising the following polyamide (B), and polyamide (A) and polyamide (B)
Is a laminated film composed of a layer (c) composed of a mixed composition (C) with a polyamide (A) which constitutes the layer (a).
%, And the mixed composition (C) constituting the layer (c) contains the ionomer resin mixture in an amount of 10% by weight or less, respectively, and is a polyamide-based laminated biaxially stretched film. Polyamide (A): 70 mol% of a polyamide constitutional unit consisting of m- and / or p-xylylenediamine and an α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the molecular chain.
Aromatic Polyamide Containing Polyamide (B): Aliphatic Polyamide Ionomer Resin Mixture: Ethylene / Acrylic Acid Copolymer Containing Acrylic Acid and / or Methacrylic Acid Content of 10 to 20% by Weight, Ethylene / Methacrylic Acid Copolymer 20 to 40% of the carboxyl groups of the polymer or ethylene / acrylic acid / methacrylic acid copolymer are neutralized, and the melt flow rate at 190 ° C. and a load of 2160 g is 0.5 to 10 g / 10 minutes or less. A mixture of 70% by weight or more of an ethylene copolymer (ionomer resin) and 30% by weight or less of another thermoplastic resin.