JP2003326656A - Multilayered structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure such as a multilayered film, which is constituted by utilizing an oxygen-absorptive polyamide resin composition capable of abating mechanical properties, particularly, a decrease in impact resistance over an extended period of time. <P>SOLUTION: This multilayered structure includes at least one layer (A) which is composed of the oxygen-absorptive polyamide resin composition. In the multilayered structure, a layer (B), which is composed of a thermoplastic resin compatible with the oxygen-absorptive polyamide resin composition, is laminated so as to be adjacent at least to one side of the layer (A). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a multilayer film having an oxygen absorbing function. Specifically, a layer formed of a thermoplastic resin having compatibility with a material forming the layer is laminated on at least one side of a polyamide resin layer having an oxygen absorbing function, and has excellent oxygen barrier properties, The present invention also relates to a multilayer film capable of maintaining the mechanical properties of packaging materials for a long period of time.

[0002]

2. Description of the Related Art Metal cans and glass bottles, which have been conventionally used as packaging containers that block the ingress of oxygen from the outside and are excellent in storage stability of contents, are made of an oxygen barrier thermoplastic resin in view of processability and cost. It is recommended that the used plastic packaging containers be replaced. The oxygen-barrier thermoplastic resin has low permeability to gaseous substances such as oxygen and carbon dioxide, is easy to process, and is transparent and has sufficient mechanical strength. Widely used polyamide (hereinafter abbreviated as nylon MXD6) obtained from polycondensation reaction of ethylene-vinyl alcohol copolymer or diamine component containing metaxylylenediamine as a main component and dicarboxylic acid component containing adipic acid as a main component Has been done.
However, in the case of a packaging container made of metal or glass, the gas permeation from the outside of the container to the inside of the container is substantially zero, whereas in the case of a packaging container made of an oxygen barrier thermoplastic resin, Gas permeation from the outside of the container to the inside of the container occurs at a non-negligible level, and the amount of gas permeation tends to increase depending on the environment in which the packaging container is stored. There was a problem with long-term storage.

In recent years, a small amount of a compound containing at least one metal atom selected from the group VIII transition metals of the Periodic Table of Elements, manganese, copper and zinc is added to and mixed with nylon MXD6, and nylon MXD6 has an oxygen absorbing function. By using this as an oxygen barrier material that constitutes a container or packaging material, oxygen that permeates from the outside of the container is nylon M
Nylon MXD6 absorbs oxygen remaining in the container as well as absorbed by XD6, so that a method of improving the storage stability of the contents more than the container using the conventional oxygen barrier thermoplastic resin is being put to practical use.

The above-mentioned oxygen absorption function is due to the generation of radicals resulting from the abstraction of hydrogen atoms from the methylene chain adjacent to the arylene group of nylon MXD6 by the above metal atoms, and the peroxy radicals generated by the addition of oxygen molecules to the radicals. It is considered to be caused by generation, abstraction of hydrogen atoms by peroxy radicals, and each of the above reactions. A packaging container made of nylon MXD6 that exhibits an oxygen absorption function by such an oxidation reaction tends to be affected by the deterioration of mechanical properties associated with the oxidation of nylon MXD6. In a PET bottle using nylon MXD6 having the above oxygen absorbing function as an intermediate layer, the amount of nylon MXD6 used is as low as around 5 wt% and the rigidity of the container itself is very high, so it may not be a problem in practice. Nylon M, which has a large amount of oxygen absorption function in the soft packaging materials such as films
The amount of XD6 used is higher than that of PET bottles, and the mechanical properties of nylon MXD6 deteriorate, and the mechanical properties of the packaging container itself, in particular, the impact resistance, decrease significantly. It was difficult to use it as a packaging container for stored items.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to reduce the deterioration of mechanical properties, especially impact resistance, for a long period of time. It is to provide a structure such as a multilayer film using

[0006]

Means for Solving the Problems As a result of intensive investigations by the present inventors on a method for solving the above problems, as a result, on at least one side of a layer made of an oxygen-absorbing polyamide resin composition,
A structure such as a multilayer film obtained by laminating layers having compatibility with the resin composition so as to be adjacent to each other has a mechanical property of the multilayer film accompanying oxidation of the layer made of the oxygen-absorbing polyamide resin composition, particularly impact resistance. It was found that the deterioration of the property can be alleviated, and that the packaging container using the same can retain the practical mechanical properties for a long period of time, and completed the present invention.

That is, the present invention relates to the VI of the Periodic Table of the Elements.
A multilayer structure comprising at least one layer (A) comprising an oxygen-absorbing polyamide resin composition containing one or more metal atoms selected from Group II transition metals, manganese, copper and zinc, the layer (A (3) A multilayer structure in which a layer (B) made of a thermoplastic resin compatible with the oxygen-absorbing polyamide resin composition is laminated so as to be adjacent to at least one side of (1).

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. The multilayer structure of the present invention includes a layer (A) made of an oxygen-absorbing polyamide resin composition and a layer (B) made of a thermoplastic resin compatible with the oxygen-absorbing polyamide resin composition.

In the present invention, the oxygen-absorbing polyamide resin composition constituting the layer (A) contains at least one metal atom selected from the group VIII transition metals of the periodic table of elements, manganese, copper and zinc. It is a polyamide resin composition.

Polyamides constituting the oxygen-absorbing polyamide resin composition used in the present invention include nylon 6, nylon 66, nylon 666, nylon 610, nylon 6T, nylon MXD6 and the like. Among them, nylon MXD6 Is preferably used because it has an excellent oxygen absorption capacity. Nylon MXD6 is obtained by polycondensing a diamine component containing metaxylylenediamine as a main component and a dicarboxylic acid component containing adipic acid as a main component. Other components include paraxylylenediamine, , 3-bis (aminomethyl) cyclohexane,
1,4-bis (aminomethyl) cyclohexane, tetramethylenediamine, hexamethylenediamine, nonamethylenediamine, 2-methyl-1,5-pentanediamine, suberic acid, azelaic acid, sebacic acid, 1,10
-Decanedicarboxylic acid, terephthalic acid, isophthalic acid,
It may be a copolymer of 2,6-naphthalenedicarboxylic acid or the like. Further, the polyamide constituting the oxygen-absorbing polyamide resin composition may be blended with other thermoplastic resin as long as it contains nylon MXD6. For example, nylon 6, nylon 66, nylon 66.
6, polyamide such as nylon 610 and nylon 6T, polyester such as polyethylene terephthalate and polybutylene terephthalate, polyolefin such as polyethylene and polypropylene, polycarbonate, polystyrene,
Examples thereof include polymers such as thermoplastic elastomers. Further, the oxygen-absorbing polyamide resin composition of the present invention, a pigment, a dye, within a range that does not impair the effects of the present invention,
Lubricants, matting agents, heat resistance stabilizers, weather resistance stabilizers, UV absorbers, nucleating agents, plasticizers, flame retardants, antistatic agents, anti-coloring agents,
An additive such as an anti-gelling agent, clay, mica, glass fiber, a filler such as zeolite can also be added, but is not limited to those shown above, the oxygen-absorbing polyamide stored in the present invention Various materials can be mixed in the resin composition.

The metal atom contained in the oxygen-absorbing polyamide resin composition used in the present invention is represented by the VI of the Periodic Table of the Elements.
It is one or more kinds of metal atoms selected from Group II transition metals, manganese, copper and zinc, and promotes the oxidation reaction of polyamide to exert the oxygen absorbing function of polyamide.

In the present invention, a compound containing a metal atom (hereinafter
It is preferable to use a metal catalyst compound). The metal catalyst compound is used in the form of an inorganic acid salt, organic acid salt or complex salt having a low valence number of the above-mentioned metal atom. As the inorganic acid salt,
Examples thereof include halides such as chlorides and bromides, sulfates, nitrates, phosphates and silicates. On the other hand, examples of the organic acid salts include carboxylates, sulfonates, phosphonates and the like. Further, a transition metal complex with β-diketone or β-keto acid ester and the like can also be used. In particular, in the present invention, it is preferable to use a carboxylate, a halide or an acetylacetonate complex containing the above metal atom since it has a good oxygen absorption function, and more preferably a stearate, an acetate or an acetylacetonate. It is a complex. In the present invention, one or more of the above metal catalyst compounds can be added to the oxygen-absorbing polyamide resin composition, but those containing a cobalt metal atom are particularly excellent in oxygen absorbing function and are preferably used.

The concentration of the metal atom contained in the oxygen-absorbing polyamide resin composition used in the present invention is not particularly limited, but is preferably in the range of 100 to 10,000 ppm. When the amount of the metal atom is less than 100 ppm, the oxygen absorbing function of the obtained oxygen absorbing polyamide resin composition is not sufficiently exhibited. On the other hand, if it is more than 10,000 ppm, oxidative deterioration of the polyamide may occur in the production process of the oxygen-absorbing polyamide resin composition, which is not preferable.

The method for producing the oxygen-absorbing polyamide resin composition used in the present invention includes melt-mixing the polyamide and the metal catalyst compound using an extruder or the like, or mixing the metal catalyst compound with a solvent to dissolve or After making into a slurry, a method of admixing with polyamide by removing the solvent after mixing with polyamide, a method of directly producing an oxygen-absorbing polyamide resin composition by adding a metal catalyst compound when synthesizing polyamide, etc. Although it can be used, among these, the method of melt mixing the polyamide and the metal catalyst compound using an extruder or the like is preferably performed because the metal catalyst compound can be easily mixed in the polyamide.

The thermoplastic resin constituting the layer (B) is compatible with the oxygen-absorbing polyamide resin composition, and specifically, nylon 6, nylon 66, nylon 610, nylon 6T, nylon. Examples include polyamide resins such as MXD6, and among them, nylon 6, nylon 66, nylon MXD6 from the viewpoint of workability and mechanical properties.
Is preferred, and nylon 6 is particularly preferred. Layer (B)
The layer may be a layer mixed with another thermoplastic resin as long as its properties are not impaired. Examples of the thermoplastic resin that can be mixed include, for example, polyamide other than the main component of the layer (B),
It can be mixed with various thermoplastic resins such as polyester typified by polyethylene terephthalate and polybutylene terephthalate, polyolefins typified by polyethylene and polypropylene, various modified polyolefins, polystyrene, polycarbonate, ethylene vinyl alcohol copolymer and the like. Furthermore, in the present invention, the layer (B) includes a pigment, a dye, a lubricant, a matting agent, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a nucleating agent, a plasticizer, in an amount that does not impair the effects of the present invention. Although flame retardants, antistatic agents, anti-coloring agents, additives such as anti-gelling agents, clay, mica, glass fibers, and fillers such as zeolite can be added,
Various materials can be mixed without being limited to those shown above.

In the multilayer structure of the present invention, one or more layers (A) made of the above oxygen-absorbing polyamide resin composition can be laminated. Further, this layer (A) is preferably laminated as an intermediate layer in the multilayer structure from the viewpoint of maintaining the mechanical properties of the multilayer structure and further from the viewpoint of safety. When a packaging container for storing articles such as foods is manufactured from this multilayer structure, if the layer (A) is laminated as the innermost layer, the one containing the low molecular weight product generated by oxidation as the main component becomes the stored product. There is a possibility of migration, which is not preferable. In addition, stacking as the outermost layer is not preferable because the packaging container may be easily damaged when an external impact is applied to the packaging container manufactured by using this.

In the multilayer structure of the present invention, the thickness of the layer (A) comprising the oxygen absorbing polyamide resin composition is preferably 1 to 200 μm, more preferably 3 to 150 μm. When the number of layers of the oxygen-absorbing polyamide resin composition is two or more, it is preferable that the total thickness is within the above range. The thickness of layer (A) is 1
If it is less than μm, a sufficient oxygen absorption function cannot be obtained. On the other hand, if the thickness is more than 200 μm, the mechanical properties of the multilayer structure tend to be significantly deteriorated when stored for a long period of time, which is not preferable.

In the multilayer structure of the present invention, a layer (B) made of a thermoplastic resin having compatibility with the layer (A) is laminated on at least one side of the layer (A) so as to be adjacent to each other.
The term "compatibility" as used herein means that it has a molecular structure similar to that of the main component of the oxygen-absorbing polyamide resin composition constituting the layer (A) and has a property of causing amide exchange under specific conditions. The layer (A) and the layer (B) are compatible with each other and are laminated adjacent to each other, so that the layers (A) and (B) are separated from each other even if the layer (A) is oxidized and deteriorated. Since it does not exist, the layer (B) can retain mechanical properties, particularly impact resistance. When the layer (A) and the layer (B) are not compatible with each other, when the layer (A) is oxidatively deteriorated, the layer (A) and the layer (B) are delaminated, and the layer (A)
It becomes impossible to keep the deterioration of the mechanical properties of the layer (B). In the multilayer structure of the present invention, the layers (B) may be laminated on both sides of the layer (A) so as to be adjacent to each other.

In the multilayer structure of the present invention, the layer thickness of the layer (A) made of the oxygen absorbing polyamide resin composition and the layer (B) made of the thermoplastic resin is the oxygen absorbing polyamide resin with respect to the total thickness of both layers. The thickness ratio of the layer (A) composed of the composition is preferably 10 to 80%, particularly preferably 15 to 70%. The thickness ratio of the layer (A) to the total thickness of both layers is the sum of the layers made of the oxygen-absorbing polyamide resin composition (denoted as ΣA) and the layer (A) adjacent to the layer made of a thermoplastic resin. Measure the total (denoted as ΣB) and divide ΣA by the sum of ΣA and ΣB to obtain 1
Refers to the value obtained by multiplying 00. By setting the thicknesses of the layer (A) and the layer (B) within the above range, it is possible to reduce the deterioration of the mechanical properties of the layer (A) by the layer (B). The thickness of each layer may be determined by calculating the necessary oxygen absorption capacity, setting the thickness of the layer (A), and then determining the thickness of the layer (B).

In the multilayer structure of the present invention, the layer (A) and the layer (B) are arranged adjacent to each other, but in the present invention, the interlayer adhesive strength between the layer (A) and the layer (B) is The measurement immediately after production is preferably 100 g / 15 mm or more, more preferably 300 g / 15 mm or more. 1
When it is less than 00 g / 15 mm, the effect of alleviating the deterioration of the mechanical properties of the layer (A) by the layer (B) becomes small, which is not preferable.

The multi-layer structure comprising the layer (A) and the layer (B) is preferably formed by coextrusion. By manufacturing by this method, both materials are mixed between the layers (A) and (B), and further amide exchange partially occurs, so that both layers are bonded with sufficient strength. The resin temperature at the time of coextrusion is higher than the melting point of each resin, but if there is no problem such as deterioration of the resin, the melting point +
Coextrusion at a temperature of 10 ° C. or higher is preferable from the viewpoint of suppressing the formation of gelled products. In addition, the multilayer structure of the present invention may be obtained by co-extruding and laminating other materials as it is as a packaging material, or the multilayer structure may be stretched and then laminated with other materials for packaging. Good as a material. A conventionally known method can be adopted when performing the stretching process.

When the multilayer structure of the present invention is actually used as a material for forming a packaging container, a layer (C) made of polyolefin is laminated on the multilayer structure made of layers (A) and (B). Is preferred. Examples of the material forming the polyolefin layer include polyethylenes such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, polyethylene produced using a metallocene catalyst, and propylene. Homopolymers, ethylene-propylene random copolymers, ethylene-propylene block copolymers, polypropylenes such as polypropylene produced using metallocene catalysts, other polymethylpentene, α-olefin copolymers, maleic anhydride, etc. It is possible to use various polyolefins such as modified adhesive polyolefin, but among them, since it is excellent in impact strength, it was manufactured using low density polyethylene, linear low density polyethylene, metallocene catalyst. Po Ethylene, ethylene-propylene random copolymer, ethylene-propylene block copolymer, polypropylene produced using a metallocene catalyst are preferable, linear low density polyethylene, polyethylene produced using a metallocene catalyst, ethylene-propylene random copolymer , Ethylene-propylene block copolymers are particularly preferred. In the polyolefin layer, if necessary, pigments, dyes, lubricants, matting agents, heat resistance stabilizers, weather resistance stabilizers, UV absorbers, nucleating agents, plasticizers, flame retardants, antistatic agents, anti-coloring agents, It is also possible to add additives such as an anti-gelling agent and fillers such as clay, mica, glass fiber and zeolite.

At least one polyolefin layer is laminated in the present invention, and it is preferable that the polyolefin layer is the innermost layer when the packaging container is constructed. By laminating in this way, the polyolefin layer can also serve as a sealant layer in a multilayer container, which is preferable. The thickness of the polyolefin layer is 10 to 2
The range is 00 μm, preferably 10 to 150 μm
m, more preferably 10 to 100 μm. When the thickness of the polyolefin layer is less than 10 μm, the heat sealing strength when forming the packaging container becomes weak, which is not preferable. Even if the thickness is set to be thicker than 200 μm, the performance of the container does not change and the material cost increases, which is not preferable.

As the method for laminating the polyolefin layer in the multilayer structure of the present invention, it is possible to laminate by a conventionally known method. For example, it is laminated by extrusion lamination on the layer (A) side of a multilayer structure consisting of the layer (A) / layer (B) via an adhesive, or the polyolefin layer / layer (A) / layer (B) is laminated. It can also be manufactured by co-extruding the resulting film using a co-extrusion device.

The multi-layer structure of the present invention comprises a laminate of layers (A) / (B). In addition to the above-mentioned polyolefin layer, other materials are used for the purpose of retaining strength and improving properties. You may laminate | stack the layer which consists of.

The multilayer structure of the present invention can be molded and used for various packaging containers. For example, it can be used as a material forming at least a part of various pouches such as a flat bag and a standing pouch, and a packaging container such as a lid and a tube. Also, various articles are stored in a packaging container made of the oxygen-absorbing polyamide resin composition of the present invention,
Can be saved. For example, carbonated drinks, juices,
Water, milk, sake, whiskey, shochu, coffee, tea,
Liquid drinks such as jelly drinks and health drinks, seasoning liquids, sauces,
Liquid ingredients such as soy sauce, dressing, liquid soup, mayonnaise, miso, seasonings such as grated spices, pasty foods such as jam, cream and chocolate paste, liquid processed foods such as liquid soups, stews, pickles and stews. Raw noodles and boiled noodles such as food, soba, udon, ramen, etc.
Typical examples include uncooked rice such as milled rice, moisture-conditioned rice, unwashed rice, cooked cooked rice, gome rice, red rice, processed rice products such as rice porridge, powder soup, and powder seasonings such as dashi stock. High-moisture foods, dried vegetables, coffee beans, coffee powder, tea, low-moisture foods represented by sweets made from grains, and other solid or solution chemicals such as pesticides and insecticides, liquids and Pasty medicine, lotion, makeup cream, lotion,
Various items such as hairdressing agents, hair dyes, shampoos, soaps, detergents can be stored.

[0027]

The present invention will be described in more detail below. However, the present invention is not limited to the following examples. The evaluation methods used in the examples and comparative examples are as follows. (1) Measurement of oxygen absorption amount of multilayer film Multilayer film 1 cut into 10 cm × 10 cm squares
The sheet was placed in a four-side sealed bag laminated with aluminum foil, sealed by heat sealing so that the air in the bag was 200 ml, and stored in a constant temperature bath at 40 ° C. until the oxygen concentration in the bag did not change. . Then, the gas in the storage container was sampled using a syringe, and the residual oxygen concentration in the bag was measured by a zirconia-type oxygen concentration meter manufactured by Toray Industries, Inc., and the oxygen absorption amount per 100 cm ^{2 of} the multilayer film was calculated. (2) Impact perforation strength measurement of multilayer film After humidity conditioning in a room at 23 ° C. and 50% RH for 1 week, film impact tester ITF-60 manufactured by Toseki Seimitsu Co., Ltd.
Using, make the tip shape 1/2 inch spherical,
The measurement was performed under the condition of ° C / 50% RH.

Example 1 Polyamide obtained by melt polycondensation of adipic acid and metaxylylenediamine and cobalt acetate tetrahydrate weighed so that the cobalt metal concentration was 500 ppm were mixed with a tumbler, The mixture was melt-kneaded with a 30 mmφ single-screw extruder, the strand was extruded from a strand die, cooled in a cooling water tank, and then pelletized with a pelletizer to prepare 2.5 mmL × 2.5 mmφ oxygen-absorbing polyamide pellets. Next, using a multi-layer film manufacturing apparatus consisting of four extruders, a feed block, a T-die, a chill roll, a take-off machine, etc., nylon 6 pellets were fed from the first extruder and the oxygen was fed from the second extruder. Absorbent polyamide pellets, maleic anhydride-modified polyethylene (hereinafter abbreviated as maleic anhydride-modified PE) pellets from the third extruder, and linear low-density polyethylene (hereinafter abbreviated as LLDPE) from the fourth extruder. Extrude nylon 6 (10 μm) / oxygen absorbing polyamide (15 μm)
m) / maleic anhydride modified PE (10 μm) / LLDP
A multilayer film having a layer structure of E (50 μm) was produced. The impact puncture strength of the film that had been subjected to a humidity control period of 1 week after production was measured to be 43 k.
It was g · cm. Then, this multilayer film was stored in a room under an atmosphere of 23 ° C. and 50% RH for 6 months, and the time-dependent changes in impact puncture strength and oxygen absorption amount were measured. The results are shown in Table 1.

Example 2 Nylon 6 pellets were fed from the first extruder to the second extruder by using a multi-layer film manufacturing apparatus comprising four extruders, a feed block, a T-die, a chill roll, a take-up machine and the like. To pellets of the oxygen-absorbing polyamide obtained in Example 1 from the third extruder, maleic anhydride-modified polypropylene (hereinafter abbreviated to maleic anhydride-modified PP) pellets from the third extruder, and propylene-ethylene random from the fourth extruder. Extruding a copolymer (hereinafter abbreviated as random PP),
Nylon 6 (10 μm) / oxygen absorbing polyamide (15
μm) / nylon 6 (10 μm) / maleic anhydride modified PP (10 μm) / LLDPE (50 μm). The impact puncture strength of the film, which had been subjected to a humidity control period of 1 week after production, was 44 kg · cm. This multilayer film is then used for a further 6 months
The sample was stored in a room at 50 ° C. and 50% RH, and the impact drilling strength and the oxygen absorption amount were measured over time. The results are shown in Table 1.

Example 3 Nylon 6 pellets were fed from the first extruder to the second extruder by using a multi-layer film manufacturing apparatus comprising four extruders, a feed block, a T-die, a chill roll, a take-up machine and the like. The pellet obtained by mixing 100 parts by weight of the oxygen-absorbing polyamide pellets obtained in Example 1 with 50 parts by weight of nylon 6 pellets was mixed with a maleic anhydride-modified polypropylene (hereinafter referred to as maleic anhydride-modified PP) from a third extruder. Abbreviated) pellets from the fourth extruder propylene-ethylene random copolymer (hereinafter abbreviated as random PP)
Extruded nylon 6 (10 μm) / oxygen absorbing polyamide (15 μm) / maleic anhydride modified PE (10
A multilayer film having a layer structure of (μm) / LLDPE (50 μm) was produced. The impact puncture strength of the film, which had been subjected to a humidity control period of 1 week after production, was 50 kg · cm. This multi-layer film is then placed at 23 ° C. and 50% R for another 6 months.
The sample was stored in a room under an H atmosphere, and the time-dependent changes in impact drilling strength and oxygen absorption amount were measured. The results are shown in Table 1.

Comparative Example 1 A film was prepared in the same manner as in Example 1 except that cobalt polyamide tetrahydrate was not mixed with the polyamide obtained by melt polycondensation of adipic acid and metaxylylenediamine. The impact puncture strength of the film, which had been subjected to a humidity control period of 1 week after production, was 46 k.
It was g · cm. Then, this multilayer film was stored in a room under an atmosphere of 23 ° C. and 50% RH for 6 months, and the time-dependent changes in impact puncture strength and oxygen absorption amount were measured. The results are shown in Table 1.

Comparative Example 2 The oxygen-absorbing polyamide obtained in Example 1 from the first extruder was used by using a multi-layer film manufacturing apparatus consisting of three extruders, a feed block, a T-die, a chill roll, a take-up machine and the like. No. 2 pellets were extruded from the second extruder with maleic anhydride-modified PE pellets, and the third extruder was extruded with LLDPE to obtain oxygen-absorbing polyamide (20 μm) / maleic anhydride-modified PE (10 μm) / LLDPE (40 μm).
A multilayer film having the above layer structure was produced, and the surface of the oxygen-absorbing polyamide layer was subjected to corona discharge treatment. Next, using a film laminator, the corona discharge treated surface of the above film and the corona treated surface of a biaxially oriented polypropylene film (hereinafter abbreviated as OPP) are laminated via a polyurethane adhesive, and the laminate is placed at 40 ° C. for 3 days. Aging and OPP
(25 μm) / oxygen-absorbing polyamide (20 μm) / maleic anhydride-modified PE (10 μm) / LLDPE (40
A multilayer film having a layer structure of (μm) was obtained. The impact puncture strength of the film, which had been subjected to a humidity control period of 1 week after production, was 19 kg · cm. Next, this multilayer film was stored in a room at 23 ° C. and 50% RH for 6 months, and the impact puncture strength and oxygen absorption were measured with time. There was a tendency to do so. The results are shown in Table 1.

Example 4 Nylon 6 pellets were fed from the first extruder to the second extruder by using a multi-layer film manufacturing apparatus comprising two extruders, a feed block, a T-die, a chill roll, a take-up machine and the like. The oxygen-absorbing polyamide pellets obtained in Example 1 were extruded to produce a multilayer film having a layer structure of nylon 6 (40 μm) / oxygen-absorbing polyamide (40 μm) / nylon 6 (40 μm). Next, this multilayer film was processed into a biaxially stretched film having a stretching ratio of 3 × 3 by using a batch type biaxial stretching device, and one surface thereof was subjected to corona discharge treatment. Next, using a film laminator, the corona-treated surface of the above film and the corona-treated surface of the linear low-density polyethylene (hereinafter abbreviated as LLDPE) having one surface corona-treated, the polyurethane adhesive And aged for 3 days at 40 ° C., nylon 6 (5 μm) / oxygen absorbing polyamide (5 μm) / nylon 6 (5 μm) / LLDPE (30
A multilayer film having a layer structure of (μm) was obtained. The impact puncture strength of the film that had been subjected to a humidity control period of 1 week after production was 23 kg.cm. Then, this multilayer film was stored in a room under an atmosphere of 23 ° C. and 50% RH for 6 months, and the time-dependent changes in impact puncture strength and oxygen absorption amount were measured.
The results are shown in Table 1.

Comparative Example 3 A film was prepared in the same manner as in Example 4, except that the polyamide obtained by melt polycondensation of adipic acid and metaxylylenediamine was not mixed with cobalt acetate tetrahydrate. The impact puncture strength of the film that had been subjected to a humidity control period of 1 week after production was measured to be 24 k.
It was g · cm. Then, this multilayer film was stored in a room under an atmosphere of 23 ° C. and 50% RH for 6 months, and the time-dependent changes in impact puncture strength and oxygen absorption amount were measured. The results are shown in Table 1.

Table 1 Time-dependent changes in various measured values (1 week / 3 months / 6 months after production) Film layer structure * Oxygen absorption amount Impact punching strength (ml / 100 cm ² ) (kg · cm ) Example 1 N6 / MXD6-Co / AD / PE 0/10/15 43/38/34 Example 2 N6 / MXD6-Co / N6 / AD / PE 0/9/15 44/40/35 Example 3 N6 / (MXD6 -Co + N6) / AD / PE 0/6/10 50/44/39 Comparative Example 1 N6 / MXD6 / AD / PE 0/0/0 46/41/38 Comparative Example 2 OPP / MXD6-Co / AD / PE 0/10/15 19/10/7 Example 4 O-N6 / O-MXD6-Co / O-N6 / PE 0/9/12 23/19/17 Comparative Example 3 O-N6 / O-MXD6 / O-N6 / PE 0/0/0 24/21/19

* In the layer structure of Table 1, each symbol is as follows. N6; Nylon 6 MXD6; Nylon MXD6 MXD6-Co; Oxygen-absorbing nylon MXD6 AD; Maleic anhydride-modified polyethylene PE; Linear low density polyethylene O-N6; Biaxially oriented nylon 6 O-MXD6-Co; Biaxially oriented Oxygen absorbing nylon MX
D6 OPP; Biaxially oriented polypropylene film

As is clear from the above examples, the multilayer film having the layer structure of the present invention absorbs oxygen and has a higher impact resistance than the multilayer film having the same layer structure having no oxygen absorption function. It was found that there was no difference in the change over time and that it had practical mechanical performance. On the other hand, in Comparative Example 2 in which a layer compatible with the layer made of the oxygen absorbing polyamide resin composition is not laminated, the impact resistance of the multilayer film is deteriorated due to the oxidation deterioration of the layer made of the oxygen absorbing polyamide resin composition. It was observed.

[0038]

Industrial Applicability The multilayer structure of the present invention has a function of absorbing oxygen, has mechanical properties equivalent to those of conventional ones, and can retain practical performance for a long period of time. Is high and industrially superior.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Soutaro Hiramatsu             5-6 Higashi-Hachiman 5-2, Hiratsuka City, Kanagawa Prefecture             Ryogas Chemical Co., Ltd. Hiratsuka Research Center F term (reference) 3E067 AA01 AA11 AB01 AB81 AB96                       BA12A BA14A BA17A BB14A                       BB25A CA06 CA30 FC01                       GB13 GD01 GD02                 3E086 AD01 AD03 AD23 BA04 BA15                       BA35 BB05 BB85 CA01 CA28                       CA29 DA08                 4F100 AK01B AK01C AK03D AK03E                       AK04 AK46A AK48B AK48C                       AK53 AL07 BA02 BA03 BA04                       BA05 BA10A BA10B BA10C                       BA10D BA10E GB16 JB16B                       JB16C JD03 JD03A JK06                       YY00                 4J002 CL001 CL011 CL031 DA066                       DA076 DA106 GG02

Claims (8)

[Claims] 1. A layer (A) comprising an oxygen-absorbing polyamide resin composition containing at least one metal atom selected from the group VIII transition metals of the Periodic Table of Elements, manganese, copper and zinc.
A multi-layer structure containing at least one layer, wherein a layer (B) made of a thermoplastic resin compatible with the oxygen-absorbing polyamide resin composition is laminated so as to be adjacent to at least one side of the layer (A). Multi-layer structure. 2. The multilayer structure according to claim 1, wherein the thermoplastic resin is at least one selected from nylon 6, nylon 66 and nylon MXD6. 3. The layer (A) has a thickness of 10 to 80% of the total thickness of the layers (A) and (B).
The described multilayer structure. 4. The layer (A) immediately after the production of a multilayer structure.
The multilayer structure according to claim 1, wherein the interlayer adhesive strength between the layer (B) and the layer (B) is 100 g / 15 mm or more. 5. The oxygen-absorbing polyamide resin composition,
The multilayer structure according to claim 1, which comprises 10 to 100% by weight of a polyamide obtained by polycondensing a diamine component containing 70 mol% or more of metaxylylenediamine and a dicarboxylic acid component containing 50 mol% or more of adipic acid. 6. The concentration of the metal atom in the layer (A) is 1
The multi-layer structure according to claim 1, which is from 00 to 10,000 ppm. 7. A multilayer structure comprising the layer (A) in the multilayer structure according to any one of claims 1 to 6 as an intermediate layer, and a layer (C) made of polyolefin laminated on the outermost side. 8. A packaging container comprising the multilayer structure according to any one of claims 1 to 7.