JPH07276591A - Polyamide type laminated biaxially stretched film - Google Patents

Abstract

PURPOSE:To obtain a laminated film having toughness and oxygen gas barrier properties, in a laminated film constituted of two or more layers among an a-layer composed of polyamide A of specific constitution, a b-layer composed of polyamide B and a c-layer composed of a mixed compsn. C of A and B, by adding an ionomer resin mixture to A in specific wt.% and also adding the same to C in specific wt.% or less. CONSTITUTION:Polyamide A contains the following ionomer resin mixture in an amt. of 0.3-10wt.% and a mixture compsn. C contains the same in an amt. of 0.3-10wt.% or less. Polyamide A is aromatic polyamide containing 70mol % or more of a polyamide constituting unit consisting of m-xylenediamine and a 6-12C alpha, omega aliphatic dicarboxylic acid in its molecular chain and polyamide B is aliphatic polyamide. The ionomer resin mixture is an ethylene/acrylic acid copolymer with acrylic acid content of 2-10wt.% and prepared by mixing 70wt.% or more of an ethylenic copolymer whose melt flow rate under load of 2160g at 190 deg.C is 0.5-10g/10min or less and 30wt.% or more of polyolefin.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is excellent in oxygen gas barrier properties, flex resistance, transparency and toughness, and is suitable for a film for packaging foods, medical products, chemicals and the like which do not like the deterioration of 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, although the film made of an aliphatic polyamide is excellent in mechanical properties such as tensile strength and bending resistance, it cannot be said to be sufficient in oxygen gas barrier property.

Therefore, a vinylidene chloride-based resin coat film, which is coated with a vinylidene chloride-based polymer latex 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 also 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. Although this film is excellent in transparency and oil resistance, it is inferior in bending resistance, so that its use is limited.

In order to obtain a film having the advantages of both the above-mentioned aliphatic polyamide film and aromatic polyamide film, that is, tensile strength, flex resistance and oxygen gas barrier property, these two polyamides are combined. A method of producing a laminated biaxially stretched film by melt coextrusion and inflation method (Japanese Patent Laid-Open No. 57-57,570).
No. 51,427) or a layer containing an aromatic polyamide as a main component between layers containing an aliphatic polyamide as a main component (JP-A-56-1557).
No. 62) is also proposed.

However, the laminated biaxially stretched film proposed in the above publication has improved flex resistance and toughness due to the contribution of the layer composed of an aliphatic polyamide, and oxygen due to the contribution of the layer composed of an aromatic polyamide. Although the gas barrier property tends to be improved, both the flex resistance and the oxygen gas barrier property do not exhibit satisfactory levels at the same time. Also,
When manufacturing a coextrusion laminated film using different kinds of polyamides as raw materials, formation of a mixture of different polyamide resins is inevitable. For example, even after the start of operation of the laminated biaxially stretched film manufacturing equipment until the steady state where products within the specifications are reached is reached, non-standard films are produced or even after reaching the steady state, There are also cut scraps called trim. Since it is virtually impossible to separately collect individual polyamides from these nonstandard films and cut scraps, 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, there is a problem that the raw material yield is lowered, the economic efficiency is impaired, and the disposal itself is costly.

From this point of view, it has been strongly desired to effectively utilize the resin mixture generated in the production of the laminated film. However, even in the above publication, no attention is paid to the reuse of these nonstandard films, cut scraps and the like.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is a polyamide-based biaxially laminated biaxial fiber that is tough and has excellent oxygen gas barrier properties, excellent flex resistance, and transparency. A laminated biaxially stretched film that provides a stretched film, and that can be produced by effectively utilizing a raw material polyamide mixture generated as a nonstandard film or a cut waste material when producing a polyamide-based laminated biaxially stretched film. Is provided.

[0009]

The present invention provides a layer (a) comprising the following polyamide (A) and the following polyamide (B):
A laminated film comprising at least two layers of a (b) layer consisting of (a) and a (c) layer consisting of a mixed composition (C) of polyamide (A) and polyamide (B), and (a)
The polyamide (A) constituting the layer is 0.3 to 10% by weight of the following ionomer resin mixture, and the mixed composition (C) constituting the layer (c) is 10% by weight of the ionomer resin mixture.
Hereinafter, each is characterized by containing. 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: Acrylic Acid and / or Methacrylic Acid Ethylene / Acrylic Acid Copolymer Containing 2-10% by Weight, Ethylene / Methacrylic Acid Copolymer Coalescing,
Alternatively, 0.5 to 10% or less of the carboxyl groups of the ethylene / acrylic acid / methacrylic acid copolymer are neutralized with metal ions, and the melt flow rate at 190 ° C. under a load of 2160 g is 0.5 to 10 g / 10. A mixture of 70% by weight or more of an ethylene-based copolymer (ionomer resin) whose content is not more than 30% and 30% by weight or less of polyolefins. 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. The polyamide (A) must contain at least 70 mol% of polyamide constituent units consisting of m- or / and p-xylylenediamine and α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the molecular chain. I have to. When the polyamide (A) having a ratio of the above-mentioned specific polyamide constitutional unit in the molecular chain of less than 70 mol% is used, the oxygen gas barrier property to be imparted to the finally obtained laminated biaxially stretched film is a target value. (15 cc / m ² · 24 H · atm or less under conditions of temperature of 25 ° C and relative humidity of 65%), which is not preferable.

Specific examples of the polyamide (A) include polymeta-xylylene adipamide, poly-meta-xylylene pimeramide, poly-meta-xylylene azelamide, poly-para-xylylene azelamide, and poly-para-xylylene decanamide. Of polymers, metaxylylene / paraxylylene adipamide copolymer, metaxylylene / paraxylylene pimeramide copolymer, metaxylylene / paraxylylene azelamide copolymer, metaxylylene / paraxylylene sepacamide copolymer Such copolymers may be mentioned.

In addition, as long as the content of the polyamide structural unit containing m- or / and p-xylylenediamine and the α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the molecular chain is 70 mol% or more, It may be a copolymer composed of a component and another polyamide constituent component. Examples of the other polyamide constituent component 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 nylon salt include hexamethylenediamine, 2,
Aliphatic diamines such as 2,4-trimethylhexamethylenediamine, piperazine bispropylamine, and heterocyclic ring- or heteroatom-containing diamines such as neopentylglycol bispropylamine, etc., and specific examples of dicarboxylic acids Examples thereof include aliphatic dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and cyclic aliphatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid.

Further, the polyamide (A) contains another thermoplastic resin compatible with the polyamide (A) in a range of 20% by weight or less, as long as it does not affect the objects and effects of the present invention. be able to. If the content of the other thermoplastic resin exceeds 20% by weight, the oxygen gas barrier property does not reach the target value, which is not preferable. Polyamide (A)
Other thermoplastic resins compatible with are other thermoplastic resins other than the polyamides and ionomer resin mixtures not exemplified above.

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 a 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. In the case of a copolymerized polyamide containing as a main component, examples of the compound capable of being copolymerized include lactams such as ε-caprolactam.

Specific examples of the aliphatic diamines constituting the nylon salt used for the copolymerization include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, decamethylenediamine and the like. Specific examples of the dicarboxylic acids include adipic acid, sebacic acid, corkic acid,
Glutaric acid, azelaic acid, β-methyladipic acid,
Examples thereof include decamethylene dicarboxylic acid, dodecamethylene dicarboxylic acid, pimelic acid and the like.

Among these polyamides (B), a homopolymer of ε-caprolactam called nylon-6,
Alternatively, polyhexamethylene adipamide called nylon-66 is preferable because it can be obtained at low cost and the biaxial stretching operation can be smoothly performed. 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), or may be a standard for producing the polyamide-based laminated biaxially stretched film of the present invention. It may be prepared by adding a raw material polyamide to a raw material polyamide mixture generated as an outer film or a cut end material (edge trim) or a raw material polyamide mixture generated. The composition (mixing ratio) is not particularly limited, but the polyamide (A)
It is preferable to select the polyamide and the polyamide (B) within a weight ratio of 7: 3 to 1: 9.

Polyamide (A), polyamide (B) and mixed composition (C) all have a high hygroscopic property, and if a hygroscopic material is 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 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 having an acrylic acid and / or methacrylic acid content of 2 to 10% by weight, an ethylene / methacrylic acid copolymer, or an ethylene / methacrylic acid copolymer. Less than 0.5 to 10% of the carboxyl groups of acrylic acid / acrylic acid copolymer are neutralized with metal ions.
It contains at least 70% by weight or more of an ethylene copolymer (ionomer resin) having a melt flow rate of 0.5 to 10 g / 10 minutes at 90 ° C. and a load of 2160 g.

The acrylic acid and / or methacrylic acid content of the ionomer resin should be 2 to 10% by weight. If it is less than 2% by weight, the dispersibility of the ionomer resin mixture in the polyamide resin is lowered, and the obtained film becomes hazy, which is not preferable. On the other hand, when it is more than 10% 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 flex resistance of the obtained film is rather decreased. The cost of the resin also increases, which is not preferable. In the above range, particularly preferable range is 4 to 8% by weight.

The degree of neutralization of the carboxyl groups of ethylene / methacrylic acid copolymer, ethylene / acrylic acid copolymer, or ethylene / methacrylic acid / acrylic acid copolymer with metal ions is less than 0.5 to 10%. Is. If the degree of neutralization with metal ions is less than 0.5%, the dispersibility of the ionomer resin mixture in the polyamide resin decreases, and the resulting film becomes hazy, which is not preferable. On the other hand, in the case of 10% or more, the dispersibility of the ionomer resin mixture in the polyamide resin is too high, the particle size of the dispersed ionomer resin mixture is small, and the effect of improving the flex resistance of the obtained film is rather reduced, and The cost of the ionomer resin mixture also increases, which is not preferable. The range of 2 to 8% is particularly preferable in the above range.

Zinc, sodium, lithium, potassium, magnesium, calcium or the like can be used as the neutralizing metal component. Zinc and sodium are particularly preferable. The melt flow rate of the ionomer resin mixture used is 190 ° C. and 0.5 to 10 under a load of 2160 g.
It needs to be 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. The melt flow rate is 10
When it is more than g / 10 minutes, the ionomer resin mixture is too finely dispersed in the polyamide resin, and the bending resistance of the obtained film is deteriorated, which is not preferable. Particularly preferable range is 1 to 8 g / 10 minutes.

As the ionomer resin mixture, the above ionomer resin itself or a mixture of the ionomer resin and polyolefins in an amount of 30% by weight or less is used. Examples of polyolefins include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-ethyl methacrylate copolymer, or these. The resin mixture etc. of can be used.
The melt flow rate of the polyolefins 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.

When the proportion of the polyolefins in the ionomer resin mixture exceeds 30% by weight, the dispersibility of the ionomer resin mixture in the polyamide resin is deteriorated and the obtained biaxially stretched laminated film becomes hazy, which is not preferable. The mixing of the resin is preferably carried out by melt-kneading the ionomer resin and the polyolefins with an extruder and pelletizing them, but is not limited thereto unless the dispersibility of the ionomer resin mixture in the polyamide resin is changed. Not a thing.

The polyamide laminated biaxially stretched film according to the present invention comprises the above-mentioned polyamide (A) (a) layer, polyamide (B) (b) layer, polyamide (A) and polyamide (B). (C) comprising at least two layers of the mixed composition (C), and
The polyamide (A) constituting the layer (a) contains the ionomer resin mixture in an amount of 0.3 to 10% by weight, preferably 0.5.
The mixed composition (C), which is contained in an amount of up to 5% by weight and constitutes the layer (c), is characterized in that it contains the ionomer resin mixture in an amount of 10% by weight or less, preferably 0.1 to 5% by weight. If the ionomer resin mixture content of the polyamide (A) constituting the layer (a) is less than 0.5% by weight, the effect of improving the bending resistance is small, and if it is less than 0.3% by weight, the effect is improved. The target value of flex resistance is further reduced (the number of pinholes is 15/77 inc.
h ² or less) cannot be achieved. On the other hand, when the content of the ionomer resin mixture exceeds 5% by weight, the effect of improving the flex resistance tends to approach saturation, and the obtained laminated film becomes hazy. This is because the appearance tends to be impaired, and when the content exceeds 10% by weight, this tendency becomes remarkable.

For the same reason, 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 5% by weight. The mixed composition (C) that constitutes the layer (c)
As a result, when the nonstandard film or the cut end material (ear trim) generated during the production of the laminated film is recycled, the ionomer resin mixture in the (a) layer or the (c) layer is naturally recycled, so In some cases, it may not be necessary to 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 at 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.

A typical layer structure is (a) /
(C), (b) / (c), (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) /
Examples thereof include (b) / (a) / (b) / (c), but are not limited to these exemplified ones.

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) containing an ionomer resin mixture, a polyamide (B), and a mixed composition (C) containing a predetermined amount of an ionomer resin mixture are used as raw materials and are substantially amorphous and not oriented. A laminated film (hereinafter referred to as "laminated unstretched film") is preferably produced 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 obtain a flat or annular laminated unstretched film. It is preferable to adopt the coextrusion method using a film. Next, the 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). 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, so the upper limit of the stretching ratio is preferably within the above range.

As the method of biaxial stretching, conventionally known stretching methods such as tenter type sequential biaxial stretching, tenter type simultaneous biaxial stretching, tubular type simultaneous biaxial stretching, etc. can be used 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 stretched 2.5 to 5 times in the machine direction by a roll type longitudinal stretching machine. By a tenter type horizontal stretching machine in the temperature range of 60 to 120 ° C. in the transverse direction of 2.5 to 5
It can be produced by stretching twice. Also,
In the case of the tenter type simultaneous biaxial stretching or the tubular type simultaneous biaxial stretching method, for example, in the temperature range of 60 to 110 ° C., it is produced by simultaneously stretching in the longitudinal and transverse directions by 2.5 to 5 times in each axial direction. You can

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 110 ° C. as a lower limit and 5 ° C. lower than the melting point of the polyamide (B) as an upper limit, whereby the room temperature dimensional stability is good.
A stretched film having an arbitrary heat shrinkage can be obtained.

The laminated biaxially stretched film, which is sufficiently heat-set by the heat treatment operation, is cooled and wound up by a conventional method. The polyamide-based laminated biaxially stretched film according to the present invention can be produced by the above method, but in view of the object of the present invention, the following physical properties, that is, under the condition of a temperature of 25 ° C. and a relative humidity of 65% are given. Oxygen permeability is 15cc / m
^The number of pinholes is 15/77 inch ² or less and the haze is 8% after being repeatedly bent for 3000 cycles by the Gelbo flex tester under the conditions of 2/24 H.atm or less, temperature 23 ° C. and relative humidity 50%. At the following levels, the oxygen gas barrier property, bending resistance, and transparency 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. If the total thickness is less than 10 μm, the oxygen gas barrier property and the flex resistance are poorly balanced, and the abrasion resistance is insufficient, so that a satisfactory film for packaging cannot be obtained. On the other hand, if the thickness exceeds 40 μm, 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.
Further, the polyamide-based laminated biaxially stretched film of the present invention,
The sealant layer can be laminated and processed into a bag-shaped product.

[0035]

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 examples below, the obtained laminated film was evaluated by the following method. Table 1 shows the ionomer resin components, and Table 2 shows the layer structure and the evaluation results of the laminated film. <MFR> Load 2160 by ASTM D-1238
It was measured at a measurement temperature of 190 ° C. <Oxygen permeability (cc / m ² · 24H · atm)> It was measured under the conditions of a temperature of 25 ° C and a relative humidity of 65% using an OXY-TRAN100 type oxygen permeability measuring device manufactured by Modern Control Co. <Bending resistance (number of pinholes / 77 inch ² )> A film cut into a size of 8 inches x 11 inches is heated at a temperature of 2
The gelbo flex tester (manufactured by Rigaku Kogyo Co., No. 901 type (MIL-B-131C
The following flexing test was repeated and the number of pin poles was measured.

The rectangular test film is formed into a cylindrical shape having a length of 8 inches, one end of the rolled cylindrical film is on the outer circumference of the disk-shaped fixed head of the tester, and the other end is on the outer circumference of the tester disk-shaped movable head. Each of them is fixed, and the movable head is moved in the direction of the fixed head by 3.5 inches along the axes of both heads that face each other in parallel (the fixed head and the movable head are opposed by a distance of 7 inches). A rotation of 440 ° between them, and then a straight line of 2.5 inches without any subsequent rotation, after which these operations are performed in reverse, and the stroke for returning the movable head to the initial position is one cycle The test was carried out at a speed of 40 cycles per minute for 3000 consecutive cycles, and then the fixed head of the tested film and the portion fixed to the outer periphery of the movable head were removed. The pin number of holes generated in the portion of inch × 11 inch, pinhole tester (Sanko Electronic Laboratory Ltd., TRD-type) by applying a voltage of 1KV was thus measured. <Haze> The film piece was attached to a sample stand of a haze meter (NDH-300A type manufactured by Nippon Denshoku Industries Co., Ltd.), the total light transmittance (Tt%) and the scattered light transmittance (Td%) were measured, and the scattered light A value obtained by dividing the transmittance by the total light transmittance (Td / T
t × 100%) was taken as the film haze.

Example 1 Polymetaxylylene 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 materials (polyamide (A) and polyamide (B) produced from another film production test (proportion (weight) of 40:60) occupy the whole. (Ionomer resin 1 content 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
Adhesively and rapidly cooled to a cast roll of, the outer layer is a polyamide (B) having a thickness of about 54 μm, the intermediate layer is a mixed composition of polyamide (A) having a weight of about 36 μm and the ionomer resin 1, and the ear trim end material composition is about 45 μm for the inner layer. To obtain an unstretched laminated film.

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 machine-stretched film was held by a tenter clip and placed 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 6 μm, the intermediate layer is about 4 μm, and the inner layer is about 5 μm, (b)
/ (A) / (c) 3 layer structure, the total thickness is about 15
A laminated biaxially stretched film having a thickness of μm was obtained. The oxygen permeability of the obtained film was measured by the method described above, and the flex resistance and haze were evaluated. The results are shown in Table 2 below together with the layer structure of the film and the like.

Examples 2 to 9, 11 and 12 In the examples described in Example 1, the kind of ionomer resin, the content ratio of 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 permeability was measured and the bending resistance and haze were evaluated in the same manner as in the same example. The results are shown in Table 2 below together with the layer structure of the film and the like.

Example 10 In the example described in Example 1, the ionomer resin 1 used in the same example was replaced with the ionomer resin 3 by ethylene-vinyl acetate copolymer (Mitsubishi Yuka Co., Ltd., Mitsubishi Polyethylene EVA25).
K) was added in an amount of 20 wt% and the mixed and extruded pelletized resin was replaced with the ionomer resin 9 to obtain a laminated biaxially stretched film by the same method as described in the same example. For the obtained film, the oxygen permeability was measured in the same manner as in the same example,
Flex resistance and haze 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 permeability was measured and the bending resistance and haze were evaluated in the same manner as in the same example. 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 permeability was measured and the bending resistance and haze were evaluated in the same manner as in the same example. The results are shown in Table 2 below together with the layer structure of the film and the like.

Comparative Example 5 Commercially available 17 μm thick vinylidene chloride biaxially stretched nylon film (manufactured by Mitsubishi Kasei Co., Ltd., Santonil S)
Oxygen permeability was measured using G) to evaluate flex resistance and haze. The results are shown in Table 2 below.

[0044]

[Table 1]

[0045]

[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 biaxially stretched nylon film From Table 2, laminated biaxially stretched film according to the present invention. Is within the numerical range intended for the oxygen gas barrier property, the bending resistance, and the haze (see Examples 1 to 12).
The film of Comparative Example has excellent flex resistance, and it is understood that the film of Comparative Example is within the targeted numerical value for the oxygen gas barrier property, but the flex resistance is outside the targeted numerical range (Comparative Examples 1 to Comparative Examples. 5).

[0047]

INDUSTRIAL APPLICABILITY The present invention has the following particularly advantageous effects, 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 resistance, transparency 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 chemicals 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.

Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location B29L 9:00 (72) Inventor Masayoshi Katsura 1000 No. 1, Higashiisoana-cho, Ushiku-shi, Ibaraki Mitsubishi Kasei Corporation Tsukuba Plant

Claims (1)

[Claims] 1. A (a) comprising the following polyamide (A):
A laminated film comprising at least two layers, a layer (b) composed of the following polyamide (B) and a layer (c) composed of a mixed composition (C) of the polyamide (A) and the polyamide (B). And the polyamide (A) constituting the layer (a) contains 0.3 to 10 of the following ionomer resin mixture.
%, And the mixed composition (C) constituting the layer (c) contains an ionomer resin mixture in an amount of 10% by weight or less, respectively, and is a polyamide-based 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: Acrylic Acid and / or Methacrylic Acid Ethylene / Acrylic Acid Copolymer Containing 2-10% by Weight, Ethylene / Methacrylic Acid Copolymer Coalescing,
Alternatively, 0.5 to 10% or less of the carboxyl groups of the ethylene / acrylic acid / methacrylic acid copolymer are neutralized with metal ions, and the melt flow rate at 190 ° C. under a load of 2160 g is 0.5 to 10 g / 10. A mixture of 70% by weight or more of an ethylene-based copolymer (ionomer resin) which is less than or equal to a minute and 30% by weight or less of polyolefins