JP2021080025A - Multilayer container - Google Patents

Abstract

To provide a multilayer container with high oxygen absorption with a small amount of iron powder.SOLUTION: The multilayer container has a layer configuration of four or more layers, in which an oxygen-permeable layer (A) containing an oxygen-permeable resin as a main component, an oxygen-absorbing layer (B) consisting of an oxygen-absorbing resin composition containing iron powder and a thermoplastic resin, an adhesive layer (C) containing an adhesive resin as a main component, and a gas barrier layer (D) containing a gas barrier resin as a main component are laminated in this order from the inner layer to the outer layer. The gas barrier resin is a polyamide resin (X) consisting of diamine units containing 70 mol% or more of meta-xylenediamine units and dicarboxylic acid units containing 85 to 96 mol% of α,ω-linear aliphatic dicarboxylic acid units and 15 to 4 mol% of aromatic dicarboxylic acid units with 4 to 20 carbon atoms. The average particle diameter of the iron powder is 1 μm or more and less than 100 μm. The thickness of the oxygen-absorbing layer (B) is 0.5 to 1.5 times the average particle diameter of the iron powder.SELECTED DRAWING: None

Description

The present invention relates to a multi-layer container, and more particularly to a deoxidizing multi-layer container.

Conventionally, canned foods have been used as packaging materials for foods and the like having a long shelf life on a yearly basis. When foods are stored in canned foods, they are highly effective in terms of various gas barrier properties such as oxygen and water vapor, but the contents cannot be visually recognized before opening, and heat treatment using a microwave oven cannot be performed. There are problems that it is difficult to take out the food when the filled food is placed on a plate or the like, the food cannot be stacked at the time of disposal after use, and the canned waste is bulky and lacks suitability for disposal.
Therefore, the application of plastic containers is also being considered for packaging containers for the purpose of long shelf life as described above. As an example, the container is made of a multi-layer material in which a deoxidizing resin layer containing an oxygen scavenger composition is arranged in a conventional container having a gas barrier property to improve the gas barrier property of the container and to remove the oxygen scavenger composition into the container itself. A packaging container with an oxygen function is being developed.

In Patent Document 1, an oxygen permeable layer, an oxygen absorbing layer, an adhesive layer and a gas barrier layer composed of a gas barrier resin are laminated, and the gas barrier resin is a polyamide composed of a metaxylylene diamine, an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid. A multilayer container which is a resin and in which the thickness of the oxygen permeable layer and the thickness of the oxygen absorbing layer are in a specific range is disclosed.
In Patent Document 2, an oxygen absorbing layer made of an oxygen absorbing resin composition containing an oxygen scavenger composition is used as an intermediate layer, and an outer layer of the gas barrier layer made of a gas barrier resin and an oxygen permeable layer made of an oxygen permeable resin are used. In a deoxidizing packaging container formed by heat-molding a deoxidizing multilayer body provided with an inner layer with the inner layer side as the inside of the container, the gas barrier resin is a polycondensation reaction between metaxylylene diamine and adipic acid. Oxygen scavenger packaging, which is a mixed resin in which the mixing ratio (mass%) of a polyamide or polyamide copolymer containing 90 mol% or more of the amide structural unit produced in 1 and an amorphous polyamide is 80:20 to 30:70. The container is listed.

International Publication No. 2015/083558 Japanese Unexamined Patent Publication No. 10-86291

As disclosed in Patent Documents 1 and 2, iron powder is widely used as an oxygen absorber in a multi-layer container having an oxygen scavenging property. However, in order to impart sufficient oxygen absorption, a large amount of iron powder is required, and the resin layer containing a high concentration of iron powder needs to be thick, so that molding defects may occur during coextrusion molding. There was a problem that the appearance of the obtained container was deteriorated.
Therefore, there has been a demand for a multi-layer container that exhibits sufficient deoxidizing properties with a small amount of iron powder.

An object to be solved by the present invention is to provide a multi-layer container having high oxygen absorption with a small amount of iron powder.

The present invention provides the following multilayer containers.
<1> An oxygen permeable layer (A) containing an oxygen permeable resin as a main component, an oxygen absorbing layer (B) composed of an oxygen absorbing resin composition containing iron powder and a thermoplastic resin, and an adhesive resin as a main component. A multi-layer container having a layer structure of four or more layers in which an adhesive layer (C) containing the adhesive layer (C) and a gas barrier layer (D) containing the gas barrier resin as a main component are laminated in this order from an inner layer to an outer layer. A dicarboxylic acid containing 70 mol% or more of rangeamine units, 85 to 96 mol% of α, ω-linear aliphatic dicarboxylic acid units having 4 to 20 carbon atoms, and 15 to 4 mol% of aromatic dicarboxylic acid units. It is a polyamide resin (X) composed of a unit, the average particle size of iron powder is 1 μm or more and less than 100 μm, and the thickness of the oxygen absorbing layer (B) is 0.5 to 1.5 of the average particle size of iron powder. Double-layered container.
<2> The thickness of the oxygen permeable layer (A) is 20 to 50% of the total thickness of the multi-layer container, and the thickness of the oxygen absorbing layer (B) is 1% or more of the total thickness of the multi-layer container. The multilayer container according to <1>, which is less than%.
<3> The multilayer container according to <1> or <2>, wherein the average particle size of the iron powder is 1 μm or more and less than 80 μm.
<4> The multilayer container according to any one of <1> to <3>, wherein the average particle size of the iron powder is 1 μm or more and less than 50 μm.
<5> The multi-layer container according to any one of <1> to <4>, wherein the content of iron powder in the multi-layer container is 0.3% by mass or more and less than 3% by mass.
<6> The multilayer container according to any one of <1> to <5>, wherein the thickness of the adhesive layer (C) is 0.1% or more and less than 3% of the total thickness of the multilayer container.
<7> An adhesive layer (E) containing an adhesive resin as a main component is laminated on the outer layer of the gas barrier layer (D), and oxygen containing iron powder and a thermoplastic resin is laminated on the outer layer of the adhesive layer (E). An oxygen absorbing layer (F) made of an absorbent resin composition is laminated, and the thickness of the oxygen absorbing layer (F) is 1% or more and less than 10% of the total thickness of the multilayer container. The multilayer container according to any one of <1> to <6>.
<8> The multi-layer container according to <7>, wherein a protective layer (G) containing a thermoplastic resin as a main component is laminated on the outer layer of the oxygen absorbing layer (F).
<9> The multi-layer container according to any one of <1> to <8>, which has a 7-layer structure.
<10> The thickness of the protective layer (G) is 30 to 40% of the total thickness of the multi-layer container, and the thickness of the oxygen absorbing layer (F) is 3% or more and 7% of the total thickness of the multi-layer container. The multilayer container according to <8> or <9>, which is less than.
<11> An adhesive layer (E) containing an adhesive resin as a main component is laminated on the outer layer of the gas barrier layer (D), and a protective layer containing a thermoplastic resin as a main component is laminated on the outer layer of the adhesive layer (E). The multilayer container according to any one of <1> to <6>, wherein (G) is laminated.
<12> The multilayer container according to any one of <1> to <11>, wherein the thickness of the gas barrier layer (D) is 2 to 20% of the total thickness of the multilayer container.
<13> Any of <1> to <12>, wherein the mass ratio of iron powder to the thermoplastic resin (iron powder / thermoplastic resin) in the oxygen absorbing layer (B) is 5/95 to 50/50. The multi-layer container described in one.
<14> The method according to any one of <1> to <13>, wherein the thermoplastic resin used in the oxygen-absorbing resin composition in the oxygen-absorbing layer (B) is a resin containing polypropylene as a main component. Multi-layer container.
<15> The thermoplastic resin used in the oxygen-absorbing resin composition in the oxygen-absorbing layer (B) is a resin containing polypropylene as a main component, and has a thermal history equal to or higher than the melting point of the resin at least once in the extruder. The multilayer container according to any one of <1> to <13>, which is received.
<16> The multilayer container according to any one of <1> to <15>, wherein the oxygen permeable resin used for the oxygen permeable layer (A) is a polypropylene resin.
<17> The multilayer container according to any one of <8> to <16>, wherein the thermoplastic resin used for the protective layer (G) is one or more selected from polypropylene resin, polyamide resin, and polyester resin. ..
<18> The multilayer container according to any one of <8> to <18>, wherein the thickness of the protective layer (G) is 20 to 50% of the total thickness of the multilayer container.
<19> The multilayer container according to any one of <1> to <18>, wherein the thickness of the oxygen absorbing layer (B) is 0.85 to 1.2 times the average particle size of iron powder.
<20> The thickness of the oxygen permeable layer (A) is 30 to 40% of the total thickness of the multilayer container, and the thickness of the oxygen absorbing layer (B) is 3% or more of the total thickness of the multilayer container 7 The multilayer container according to any one of <1> to <19>, which is less than%.
<21> The multilayer container according to any one of <1> to <20>, wherein the average particle size of the iron powder is 1 μm or more and less than 40 μm.
<22> The multilayer container according to any one of <1> to <21>, wherein the iron powder is used as an oxygen scavenger composition composed of iron powder and a metal halide.
<23> The multilayer container according to <22>, wherein the oxygen scavenger composition has an average particle size of 0.05 to 0.2 mm.
<24> The multilayer container according to <22> or <23>, wherein the oxygen scavenger composition is an oxygen scavenger composition in which the surface of iron powder is coated with a metal halide.

In addition, in this specification, "containing as a main component" means that it contains preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 98% by mass or more, and does not impair the effect of the present invention. Other components may be included as long as it is within the range.

The multi-layer container of the present invention has high oxygen absorption with a small amount of iron powder.

The multilayer container of the present invention includes an oxygen permeable layer (A) containing an oxygen permeable resin as a main component, an oxygen absorbing layer (B) composed of an oxygen absorbing resin composition containing iron powder and a thermoplastic resin, and an adhesive resin. The adhesive layer (C) containing as a main component and the gas barrier layer (D) containing a gas barrier resin as a main component have a layer structure of four or more layers in which the inner layer is laminated in this order, and the gas barrier resin is a metaxili. A dicarboxylic acid containing 70 mol% or more of rangeamine units, 85 to 96 mol% of α, ω-linear aliphatic dicarboxylic acid units having 4 to 20 carbon atoms, and 15 to 4 mol% of aromatic dicarboxylic acid units. It is a polyamide resin (X) composed of a unit, the average particle size of iron powder is 1 μm or more and less than 100 μm, and the thickness of the oxygen permeable layer (A) is 0.5 to 1.5 of the average particle size of iron powder. It is double.

In addition to the oxygen permeable layer (A), the oxygen absorbing layer (B), the adhesive layer (C) and the gas barrier layer (D), the multilayer container of the present invention may further have another layer, if necessary. ..
For example, an adhesive layer (E) containing an adhesive resin as a main component is laminated on the outer layer of the gas barrier layer (D), and an oxygen-absorbing resin containing iron powder and a thermoplastic resin on the outer layer of the adhesive layer (E). The oxygen absorbing layer (F) made of the composition may be laminated. Further, a protective layer (G) containing a thermoplastic resin as a main component may be laminated on the outer layer of the oxygen absorbing layer (F).
Further, an adhesive layer (E) containing an adhesive resin as a main component is laminated on the outer layer of the gas barrier layer (D), and a protective layer (G) containing a thermoplastic resin as a main component is laminated on the outer layer of the adhesive layer (E). May be laminated.
In particular, the seven-layered multi-layer container including the layer (F) and the layers (A) to (G) are laminated has the oxygen absorbing layers (B) and () on the inner layer side and the outer layer side of the gas barrier layer (D), respectively. Since it has F), it can absorb not only oxygen inside the container but also oxygen entering from outside the container, so that oxygen permeates into the container immediately after retort treatment and after heat sterilization. It can be prevented more effectively.

[1. Oxygen permeable layer (A)]
The oxygen permeable layer (A) serves as an isolation layer that prevents the contents in the container from coming into direct contact with the oxygen absorbing layer (B), and the oxygen absorbing layer (B) fully exerts its oxygen absorbing function. It also plays a role of quickly and efficiently permeating oxygen in the container so that it can be permeated.

The oxygen permeable layer (A) contains an oxygen permeable resin as a main component.
As the oxygen permeable resin, a thermoplastic resin is preferably used. For example, polyolefins such as polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-propylene copolymer, propylene-ethylene block copolymer; ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester. Polyethylene copolymers such as copolymers, ethylene-methacrylic acid copolymers, and ethylene-methacrylic acid ester copolymers; graft polymers of the polyolefins or the polyolefin copolymers and silicon resins; polyesters such as polyethylene terephthalate. Copolymers such as nylon 6 and nylon 66; ionomers; elastomers and the like. These may be used alone or in combination of two or more.
Further, the oxygen permeable resin is preferably compatible with the oxygen absorbing resin composition used for the oxygen absorbing layer (B), and by selecting a resin compatible with each other, the oxygen permeable layer (A) and Each resin of the oxygen absorption layer (B) can be co-extruded and laminated and bonded.
As the oxygen permeable resin, a polypropylene resin is preferable from the viewpoint of easy peeling property and heat resistance.

The oxygen permeable layer (A) often serves as a sealant layer as the innermost layer of the multilayer container, and it is preferable to select a resin capable of heat sealing, but a heat sealing layer may be further provided on the inner surface side. If necessary, additives such as colorants, fillers, antistatic agents, and stabilizers can be added to the resin constituting the innermost layer.

As described above, the oxygen permeable layer (A) plays a role of an isolation layer between the stored matter in the container and the oxygen absorbing layer (B), and also plays a role of quickly and efficiently permeating oxygen in the container. Required. ^{Therefore, the oxygen permeability of the oxygen permeable layer (A) is at least 100 ml / m 2} · day regardless of the presence or absence of other layers such as the heat seal layer and the layer thickness of the oxygen permeable layer (A) itself. -Atm (23 ° C., 100% RH) or higher is preferable.
The thickness of the oxygen permeable layer (A) is preferably 20 to 50%, more preferably 25 to 45% of the total thickness of the multilayer container from the viewpoint of achieving both strength, appearance, moldability and oxygen permeability. 30-40% is more preferable. In the present invention, the thickness ratio of each layer to the total thickness of the multilayer container is measured by the method described in Examples.
Further, the oxygen permeable layer (A) may be the non-porous thermoplastic resin layer or a microporous film or a non-woven fabric made of the thermoplastic resin, but from the viewpoint of strength, appearance and moldability, the oxygen permeable layer (A) may be a microporous film or a non-woven fabric made of the thermoplastic resin. The thermoplastic resin layer having no pores is preferable.

[2. Oxygen absorption layer (B)]
The oxygen absorbing layer (B) plays a role of absorbing oxygen that cannot be completely blocked by the gas barrier layer (D) and invades from the outside of the container, and at the same time, oxygen in the container is transferred to the oxygen permeable layer (A). It also plays a role of absorbing through.

The oxygen absorbing layer (B) is made of an oxygen absorbing resin composition containing iron powder and a thermoplastic resin.
The oxygen-absorbing resin composition is a resin composition in which iron powder is kneaded and dispersed in a thermoplastic resin.

The iron powder is not particularly limited as long as it can be dispersed in the resin and can cause a deoxygenation reaction, and iron powder usually used as an oxygen scavenger can be used. As specific examples of iron powder, reduced iron powder, sponge iron powder, sprayed iron powder, iron grinding powder, electrolytic iron powder, crushed iron and the like can be used. Further, iron powder having a small content of oxygen, silicon and the like as impurities is preferable, and iron powder having a metallic iron content of 95% by mass or more is particularly preferable.
The content of the iron powder in the oxygen absorbing layer (B) is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, and further preferably 20 to 35% by mass. Within this range, good deoxidizing performance can be exhibited without adversely affecting the moldability and appearance of the container.

The average particle size of the iron powder is 1 μm or more and less than 100 μm, preferably 1 μm or more and less than 80 μm, more preferably 1 μm or more and less than 50 μm, and further preferably 1 μm or more and less than 40 μm.
The maximum particle size of the iron powder is preferably 150 μm or less, more preferably 100 μm or less, still more preferably 80 μm or less, still more preferably 70 μm or less. The maximum particle size and the average particle size of the iron powder are measured by the method described in Examples.
When the particle size of the iron powder is within the above range, sufficient deoxidizing property can be exhibited with a small amount of iron powder. Further, since the iron powder has a small particle size and is excellent in deoxidizing property, the oxygen absorbing layer containing the iron powder can be thinned, and a container having excellent moldability and excellent appearance can be obtained.

The mass ratio of iron powder to the thermoplastic resin (iron powder / thermoplastic resin) in the oxygen absorbing layer (B) is preferably 5/95 to 50/50, more preferably 10/90 to 40/60, and even more preferably. Is 20/80 to 35/65. Within this range, good deoxidizing performance can be exhibited without adversely affecting the moldability and appearance of the container.

From the viewpoint of deoxidizing performance, iron powder is preferably used as an oxygen scavenger composition composed of iron powder and a metal halide. Metal halides enhance oxygen absorption performance by acting catalytically on the oxygen absorption reaction of metallic iron.
Preferred specific examples of metals in metal halides include at least one selected from the group consisting of alkali metals, alkaline earth metals, copper, zinc, aluminum, tin, iron, cobalt and nickel. In particular, lithium, potassium, sodium, magnesium, calcium, barium and iron are preferable. In addition, preferred specific examples of the halide include chloride, bromide, and iodide, and chloride is particularly preferable.
The blending amount of the metal halide is preferably 0.1 to 20 parts by mass per 100 parts by mass of iron powder. It is preferable that substantially the entire amount of the metal halide is attached to the metallic iron and there is almost no metal halide freed in the deoxidizer composition, and when the metal halide works effectively, it is preferable. , 0.1 to 5 parts by mass is sufficient.

In the present invention, an oxygen scavenger composition in which a metal halide is attached to iron powder is preferable, and an oxygen scavenger composition in which the surface of the iron powder is coated with a metal halide is more preferable.
The metal halide is preferably added by a method that does not easily separate from metallic iron. For example, a method of pulverizing and mixing using a ball mill, a speed mill, or the like to embed fine metal halide fine particles on the surface of iron powder. , A method of adhering the metal halide fine particles to the surface of the iron powder using a binder, and a method of mixing and drying the metal halide aqueous solution and the iron powder to attach the metal halide fine particles to the surface of the iron powder are preferable. That is, the oxygen scavenger composition is preferably prepared by mixing an aqueous solution of a metal halide with iron powder and then drying to remove water.

The oxygen scavenger composition preferably has a low water content, and the water content of the oxygen scavenger composition is preferably 0.2% by mass or less, more preferably 0.1% by mass or less. The oxygen scavenger composition obtains water and exhibits an oxygen absorbing function when the multilayer container of the present invention is used as a packaging material. The oxygen scavenger composition of the iron powder main agent is used as a granular material, and the size thereof is preferably 0.3 mm or less, more preferably 0.2 mm or less, still more preferably 0.05 to 0.2 mm in terms of average particle size. Is.

As the thermoplastic resin used in the oxygen-absorbing resin composition in the oxygen-absorbing layer (B), a thermoplastic resin having a Vicat softening point of 110 to 130 ° C. is preferable. By using a thermoplastic resin having a softening point in the above range, it is possible to prevent local overheating around the oxygen scavenger composition in the oxygen scavenging resin composition during thermoforming of the oxygen scavenger multilayer body. , It becomes possible to mold into a container having a good appearance.
Specific examples of the thermoplastic resin used in the oxygen-absorbing resin composition include polyolefins such as polyethylene, polypropylene, polybutadiene, and polymethylpentene, elastomers and modified products thereof, or mixed resins thereof. Of these, a resin containing polypropylene as a main component is preferably used. Further, the thermoplastic resin used in the oxygen-absorbing resin composition in the oxygen-absorbing layer (B) may be subjected to a thermal history equal to or higher than the melting point of the resin at least once in the extruder, and a so-called recycled resin is used. You can also do it. The recycled resin may be a single resin or a mixture as long as it contains the above-mentioned thermoplastic resin as a main component. For example, crushed offcuts generated when the deoxidizing multilayer body or multi-layer container of the present invention is formed, or crushed crushed material is melted again and extruded into a strand shape and then pelletized, or a mixture thereof. Can be used as a recycled resin. From the viewpoint of cost, it is preferable to use a resin that has undergone a heat history equal to or higher than the melting point of the resin at least once in the extruder, that is, a recycled resin.

It is preferable to add calcium oxide to the oxygen-absorbing resin composition from the viewpoint of preventing foaming and improving the neglecting property. In addition, if necessary, antioxidants such as phenol-based and phosphorus-based, colorants such as organic or inorganic dyes and pigments, dispersants such as silane-based and zeolite-based, polyacrylic acid-based water absorbents, and silica. , Fillers such as clay, and additives such as gas adsorbents such as zeolite and activated carbon can be added.

The oxygen-absorbing resin composition is obtained by kneading an oxygen scavenger composition composed of iron powder and a metal halide and a thermoplastic resin, and further kneading an additive such as calcium oxide as necessary to obtain a thermoplastic resin. It is obtained by uniformly dispersing the oxygen scavenger composition therein. When adding an additive, from the viewpoint of uniformly dispersing the additive, the additive is first kneaded with a thermoplastic resin to prepare an additive-containing resin composition, and then the oxygen scavenger composition and the thermoplastic. It is preferable to prepare an oxygen-absorbing resin composition by kneading the resin and the additive-containing resin composition.

The thickness of the oxygen absorbing layer (B) is 0.5 to 1.5 times, preferably 0.6 to 1.5 times, the average particle size of the iron powder, and is preferably 0.7 to 1.5 times. It is more preferably double, 0.7 to 1.45 times, further preferably 0.7 to 1.4 times, and further preferably 0.8 to 1.3 times. Is even more preferable, and 0.85 to 1.2 times is even more preferable. When the thickness of the oxygen absorbing layer and the average particle size of the iron powder are in this ratio, it is considered that the stacking and aggregation of the iron powder in the oxygen absorbing layer (B) are suppressed and the iron oxidation reaction rate is improved. .. On the other hand, when the thickness of the oxygen absorbing layer exceeds 1.5 times, the oxidation reaction rate of iron decreases. If the thickness of the oxygen absorbing layer is less than 0.5 times, the iron powder protrudes from the oxygen absorbing layer, resulting in poor appearance.
The thickness of the oxygen absorbing layer (B) is preferably 1% or more and less than 10%, more preferably 2% or more and less than 8%, and 3% or more and 7% of the total thickness of the multilayer container. It is more preferably less than. Within the above range, it is excellent in moldability and appearance while exhibiting sufficient oxygen absorption performance.
Further, the ratio of the thickness of the oxygen permeable layer (A) to the oxygen absorbing layer (B) [(A) / (B)] is 20/10 from the viewpoint of achieving both strength, appearance, moldability and oxygen absorption performance. It is preferably ~ 50/1, more preferably 25/8 to 45/2, and even more preferably 30/7 to 40/3.

[3. Adhesive layer (C)]
The adhesive layer (C) plays a role of adhering the oxygen absorption layer (B) and the gas barrier layer (D) with sufficient strength.
The adhesive layer (C) contains an adhesive resin as a main component.
The adhesive resin is not particularly limited, and a known adhesive thermoplastic resin can be used. Examples thereof include acid-modified polyolefins obtained by modifying an olefin resin with an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, and maleic anhydride. These may be used alone or in combination of two or more. As the adhesive resin, an acid-modified polyolefin in which the same resin as the resin constituting the oxygen absorbing layer (B) is modified with an unsaturated carboxylic acid is preferable from the viewpoint of adhesion to the oxygen absorbing layer (B), for example, oxygen. When the resin used for the absorption layer (B) is a resin containing polypropylene as a main component, the adhesive resin is preferably an acid-modified thermoplastic resin containing polypropylene as a main component.

The thickness of the adhesive layer (C) is preferably 0.1% or more and less than 10%, more preferably 0.1% or more and less than 5%, and further more preferably 0.1% or more and less than 3% of the total thickness of the multilayer container. It is preferable, and more preferably 0.5% or more and less than 2.7%. The adhesive layer (C) is preferably relatively thin from the viewpoint of increasing the thickness and material selectivity of the other layer and improving the adhesiveness. When the thickness of the adhesive layer (C) is within the above range, not only the adhesiveness is excellent, but also the appearance, moldability, and barrier property of the multi-layer container are excellent.

[4. Gas barrier layer (D)]
The gas barrier layer (D) plays a role of blocking oxygen entering from the outside of the container.
The gas barrier layer (D) contains a gas barrier resin as a main component, and the gas barrier resin contains a diamine unit containing 70 mol% or more of a metaxylylene diamine unit and an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. It is a polyamide resin (X) composed of a dicarboxylic acid unit containing 85 to 96 mol% of an acid unit and 15 to 4 mol% of an aromatic dicarboxylic acid unit.

The diamine unit in the polyamide resin (X) contains 70 mol% or more of the metaxylylenediamine unit, preferably 80 to 100 mol%, more preferably 90 to 100 mol%, from the viewpoint of exhibiting excellent gas barrier properties. is there.
Examples of compounds that can constitute a diamine unit other than the m-xylylenediamine unit include aromatic diamines such as paraxylylenediamine, 1,3-bis (aminomethyl) cyclohexane, and 1,4-bis (aminomethyl) cyclohexane. Examples thereof include, but are not limited to, linear or branched aliphatic diamines such as alicyclic diamine, tetramethylenediamine, hexamethylenediamine, nonamethylenediamine, 2-methyl-1,5-pentanediamine and the like.

The dicarboxylic acid unit in the polyamide resin (X) contains 85 to 96 mol% of α, ω-linear aliphatic dicarboxylic acid unit having 4 to 20 carbon atoms and 15 to 4 mol% of aromatic dicarboxylic acid unit. Of the dicarboxylic acid units in the polyamide resin (X), the content of α, ω-linear aliphatic dicarboxylic acid units having 4 to 20 carbon atoms is preferably 88 to 96 mol%, more preferably 90 to 94 mol%. The content of the aromatic dicarboxylic acid unit is preferably 12 to 4 mol%, more preferably 10 to 6 mol%.

By containing 85 mol% or more of α, ω-linear aliphatic dicarboxylic acid units having 4 to 20 carbon atoms among the dicarboxylic acid units, it is possible to avoid a decrease in gas barrier property and an excessive decrease in crystallinity. Further, when the aromatic dicarboxylic acid unit is contained in an amount of 4 mol% or more, the amorphous property of the polyamide resin (X) is increased and the crystallization rate is lowered, so that the thermoformability at the time of container molding is improved.

If the content of the aromatic dicarboxylic acid unit exceeds 15 mol%, the polymerization of the polyamide resin (X) does not reach the melt viscosity required for molding the multilayer container, which makes it difficult to prepare the multilayer container. Further, since the polyamide resin (X) shows almost no crystallinity, the multilayer container using the polyamide resin (X) as a gas barrier layer is subjected to hot water immersion treatment at 80 to 100 ° C. or pressurized hot water treatment at 100 ° C. or higher. If heat sterilization such as is performed or storage at a high temperature is performed, whitening becomes large, which is not preferable.

Examples of compounds that can constitute an α, ω-linear aliphatic dicarboxylic acid unit having 4 to 20 carbon atoms include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,10-. Examples thereof include, but are not limited to, decandicarboxylic acid, 1,11-undecanedicarboxylic acid, and 1,12-dodecanedicarboxylic acid. These can be used alone or in combination of two or more. Of these, adipic acid is preferred.

Examples of the compound capable of constituting the aromatic dicarboxylic acid unit include, but are not limited to, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and the like. These can be used alone or in combination of two or more. Among these, isophthalic acid is preferable from the viewpoint of sublimation property and availability.

The oxygen permeation coefficient of the polyamide resin (X) at 23 ° C. and 60% RH environment is preferably 0.09 ml · mm / m ² · day · atm or less, more preferably 0, from the viewpoint of good gas barrier properties. .05 to 0.09 ml · mm / m ² · day · atm, more preferably 0.05 to 0.070 ml · mm / m ² · day · atm. The oxygen permeability coefficient can be measured according to ASTM D3985, and can be measured using, for example, "OX-TRAN 2/21" manufactured by MOCON.

The polyamide resin (X) contains a diamine component containing 70 mol% or more of m-xylylenediamine, an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, 85 to 96 mol%, and an aromatic dicarboxylic acid, 15 to 4 mol. It can be obtained by polycondensing with a dicarboxylic acid component containing%. A small amount of monoamine or monocarboxylic acid may be added as a molecular weight modifier during polycondensation.

The polyamide resin (X) is preferably produced by polycondensation by a melt polymerization method and then solid phase polymerization. Examples of the melt polycondensation method include a method in which a nylon salt composed of a diamine component and a dicarboxylic acid component is heated in the presence of water under pressure and polymerized in a molten state while removing the added water and condensed water. Be done. Further, a method of polycondensing by directly adding the diamine component to the molten dicarboxylic acid component can also be mentioned. In this case, in order to keep the reaction system in a uniform liquid state, the diamine component is continuously added to the dicarboxylic acid component, and during that time, the reaction system is raised so that the reaction temperature does not fall below the melting points of the oligoamide and polyamide resins produced. Polycondensation proceeds while warming.

Solid-phase polymerization is preferably carried out after the polymer obtained by melt polycondensation is once taken out. As the heating device used in solid phase polymerization, a batch type heating device that is superior in airtightness and can highly cut off contact between oxygen and the polyamide resin is preferable to a continuous heating device, and in particular, a tumble dryer and a conical A rotating drum type heating device called a dryer, a rotary dryer, or the like and a conical heating device having a rotating blade inside called a Nauta mixer can be preferably used, but the present invention is not limited thereto.

The solid-phase polymerization step of the polyamide resin is, for example, the first step of increasing the crystallinity of the polyamide resin so that the polyamide resin pellets do not fuse with each other or the polyamide resin pellets adhere to the inner wall of the apparatus. It is preferable to proceed by the second step of increasing the molecular weight of the above, and the third step of cooling the polyamide resin after advancing the solid phase polymerization to a desired molecular weight. The first step is preferably performed at a temperature equal to or lower than the glass transition temperature of the polyamide resin. The second step is preferably performed under reduced pressure at a temperature lower than the melting point of the polyamide resin, but is not limited thereto.

Polyamide resin (X) is a lubricant, a matting agent, a heat-resistant stabilizer, a weather-resistant stabilizer, an ultraviolet absorber, a crystallization nucleating agent, a plasticizer, a flame retardant, an antistatic agent, as long as the effects of the present invention are not impaired. Any additive such as an anti-coloring agent and an anti-gelling agent may be contained.

The thickness of the gas barrier layer (D) is not particularly limited, but from the viewpoint of gas barrier property, transparency and cost, the total thickness of the multilayer container is preferably 2 to 20%, more preferably 5 to 15%, still more preferably. It is 5 to 10%.

[5. Adhesive layer (E)]
The adhesive layer (E) serves to bond the gas barrier layer (D) to the oxygen absorbing layer (F) or the protective layer (G) with sufficient strength.
The adhesive layer (E) preferably contains an adhesive resin as a main component. As the adhesive resin, the above-mentioned adhesive thermoplastic resin can be used, and may be the same as or different from the adhesive resin used in the adhesive layer (C).
The thickness of the adhesive layer (E) is preferably 0.1% or more and less than 10%, more preferably 0.1% or more and less than 5%, and further more preferably 0.1% or more and less than 3% of the total thickness of the multilayer container. It is preferable, and more preferably 0.5% or more and less than 2.7%. The adhesive layer (E) is preferably relatively thin from the viewpoint of increasing the thickness and material selectivity of the other layer and improving the adhesiveness. When the thickness of the adhesive layer (E) is within the above range, not only the adhesiveness is excellent, but also the appearance, moldability, and barrier property of the multi-layer container are excellent.

[6. Oxygen absorption layer (F)]
The oxygen absorption layer (F) plays a role of absorbing oxygen entering from the outside of the container and also plays a role of protecting the gas barrier layer (D).
The oxygen absorbing layer (F) is made of an oxygen absorbing resin composition containing iron powder and a thermoplastic resin.
The oxygen-absorbing resin composition includes [2. It is preferable to use the oxygen-absorbing resin composition described in [Oxygen-absorbing layer (B)]. Further, it may be the same as or different from the oxygen-absorbing resin composition used in the oxygen-absorbing layer (B), but it is preferable that they are the same.
The thickness of the oxygen absorbing layer (F) is preferably 1% or more and less than 10%, more preferably 2% or more and less than 8%, and 3% or more and less than 7% of the total thickness of the multilayer container. It is more preferable to have. Within the above range, it is excellent in moldability and appearance while exhibiting sufficient oxygen absorption performance.

[7. Protective layer (G)]
The protective layer (G), which may be laminated on the outer layer of the adhesive layer (E) or the oxygen absorbing layer (F), serves to protect the gas barrier layer (D) or the oxygen absorbing layer (F).
The protective layer (G) preferably contains a thermoplastic resin as a main component. For example, polyolefins such as polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-propylene copolymer, propylene-ethylene block copolymer; ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester. Polyethylene copolymers such as copolymers, ethylene-methacrylic acid copolymers, and ethylene-methacrylic acid ester copolymers; graft polymers of the polyolefins or the polyolefin copolymers and silicon resins; polyesters such as polyethylene terephthalate. Copolymers such as nylon 6 and nylon 66; ionomers; elastomers and the like. These may be used alone or in combination of two or more. Among them, at least one selected from the group consisting of polypropylene resin, polyamide resin and polyester resin is preferable, and polypropylene resin is more preferable.
The thickness of the protective layer (G) is not particularly limited and varies depending on the layer structure of the multilayer container. For example, the oxygen permeable layer (A), the oxygen absorbing layer (B), the adhesive layer (C), and the gas barrier layer (D). In the case of a 7-layer structure in which the adhesive layer (E), the oxygen absorption layer (F) and the protective layer (G) are laminated in this order from the inner layer to the outer layer, 20 to 50% of the total thickness of the multilayer container is preferable, and 25 ~ 45% is more preferred, and 30-40% is even more preferred.
Further, the oxygen permeable layer (A), the oxygen absorbing layer (B), the adhesive layer (C), the gas barrier layer (D), the adhesive layer (E) and the protective layer (G) were laminated in this order from the inner layer to the outer layer 6 In the case of the layer structure, the thickness of the protective layer (G) is preferably 20 to 50%, more preferably 30 to 50%, still more preferably 35 to 50% of the total thickness of the multilayer container.
Further, in a multi-layer container having a 7-layer structure, the ratio of the thickness of the protective layer (G) and the oxygen absorbing layer (F) [(G) / (F)] achieves both strength, appearance, moldability and oxygen absorption performance. From the viewpoint of making the mixture, it is preferably 20/10 to 50/1, more preferably 25/8 to 45/2, and even more preferably 30/7 to 40/3.

[8. Characteristics of multi-layer containers, manufacturing methods, applications, etc.]
The total thickness of the multilayer container is preferably 0.2 to 2.0 mm, more preferably 0.3 to 1.8 mm, from the viewpoint of rigidity, impact resistance, and barrier property as a container. From the viewpoint of impact resistance and strength, it is more preferably 0.8 to 1.5 mm, further preferably 0.8 to 1.3 mm, and further preferably from the viewpoint of moldability and lightness. It is 0.3 to 1.0 mm, and even more preferably 0.3 to 0.8 mm.

The content of iron powder in the multilayer container is preferably 0.2% by mass or more and less than 8% by mass, more preferably 0.3% by mass or more and less than 6% by mass, and 0.3% by mass. % Or more and less than 5% by mass, more preferably 0.3% by mass or more and less than 3% by mass, and even more preferably 0.5% by mass or more and less than 3% by mass. It is more preferably more than mass% and less than 3 mass%. When the iron powder content is in the above range, the appearance and moldability are excellent while maintaining oxygen absorption.

Each of the above layers can be laminated by appropriately combining known methods such as a coextrusion method, various laminating methods, and various coating methods, depending on the properties of each layer material, the processing purpose, the processing process, and the like. For example, after melt-kneading the materials constituting each layer with an extruder corresponding to each layer of the oxygen permeable layer (A), the oxygen absorbing layer (B), the adhesive layer (C) and the gas barrier layer (D), a T-die, The oxygen scavenging layer (A), the oxygen absorbing layer (B), the adhesive layer (C) and the gas barrier layer (D) were laminated in this order from the inner layer to the outer layer by simultaneous melt extrusion through a multilayer multiplex die such as a circular die. A multilayer sheet having a layer structure of four or more layers can be obtained as a deoxidizing multilayer body.
The obtained deoxidizing multilayer body can be molded into a multilayer container having a predetermined shape by heat-molding with the inner layer side thereof as the inside of the container. As a molding method, vacuum forming, compressed air molding, plug-assisted molding and the like can be applied. On the other hand, the materials constituting each layer are melt-kneaded with an extruder corresponding to each layer of the oxygen permeable layer (A), the oxygen absorbing layer (B), the adhesive layer (C) and the gas barrier layer (D), and then hollowed out by a circular die. An oxygen scavenger multilayer container may be obtained by melt-extruding the shape of the parison and blowing molding it with a mold. Further, the molding temperature at this time can be selected in the range of 160 to 175 ° C. by using the polyamide resin (X) having a specific composition as the gas barrier resin, and the molding process in a relatively low temperature range becomes possible. .. Heating for container molding can be performed by contact heating or non-contact heating, but contact heating can reduce the temperature gradient generated in the oxygen scavenging multilayer body as much as possible, and each layer can be heated. It is possible to reduce the appearance defects of the container such as uneven elongation.

The multi-layer container of the present invention is suitable for packaging various articles because it has excellent oxygen barrier properties and oxygen absorption properties, and also has excellent flavor retention of the contents.
The objects to be preserved in the multi-layer container of the present invention include beverages such as milk, dairy products, juices, coffee, teas, and alcoholic beverages; liquid seasonings such as sauces, soy sauces, and dressings, soups, stews, curries, and infant cooking. Foods, cooked foods such as nursing care cooked foods; paste-like foods such as jam, mayonnaise, ketchup, jelly; marine products such as tuna and fish and shellfish; dairy products such as cheese and butter; meat, salami, sausage, ham, etc. Processed livestock products; Vegetables such as carrots and potatoes; Eggs; Noodles; Rice before cooking, Cooked rice, Processed rice products such as rice porridge; Powdered seasonings, powdered coffee, powdered milk for infants, powdered diet Foods, dried vegetables, dried foods such as senbei; chemicals such as pesticides and pesticides; pharmaceuticals; cosmetics; pet foods; miscellaneous goods such as shampoos, rinses and detergents; various articles can be mentioned. Among these, jelly using fruit meat, fruit juice, coffee, etc., which is subjected to heat sterilization treatment such as boiling treatment and retort treatment, cooked rice, processed rice products, cooked foods for infants, nursing cooked foods, curry, soup Suitable for stews, jams, mayonnaises, ketchups, pet foods, and processed marine products.

In addition, before and after filling these objects to be preserved, the multi-layer container and / or the objects to be preserved can be sterilized in a form suitable for the objects to be preserved. As sterilization methods, hot water treatment at 100 ° C or lower (boil treatment), pressurized hot water treatment at 100 ° C or higher (retort treatment), heat sterilization such as ultra-high temperature heat treatment at 130 ° C or higher, electromagnetic waves, microwaves, etc. Examples thereof include electromagnetic wave sterilization using electromagnetic waves such as gamma rays, gas treatment using gas such as ethylene oxide, and chemical sterilization using chemicals such as hydrogen peroxide and hypochlorous acid.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Analysis method / evaluation method>
(1) Relative Viscosity 0.2 g of pellet-shaped sample was precisely weighed and dissolved in 20 ml of 96% sulfuric acid with stirring at 20 to 30 ° C. After completely dissolving, 5 ml of the solution was immediately taken into a Canon Fenceke type viscometer, left in a constant temperature bath at 25 ° C. for 10 minutes, and then the drop time (t) was measured. The falling time (t ₀ ) of 96% sulfuric acid itself was also measured in the same manner. The relative viscosity was calculated from t and t _{0 by the following equation.}
Relative viscosity = t / t ₀

(2) Glass transition temperature and melting point Using a differential scanning calorimeter (“DSC-60” manufactured by Shimadzu Corporation), DSC measurement (differential scanning calorimetry) was performed at a heating rate of 10 ° C./min under a nitrogen stream. The glass transition temperature (Tg) and melting point (Tm) were determined.

(3) Measurement of average particle size and maximum particle size of iron powder Using a laser diffraction / scattering type particle size distribution measuring device "SK Laser Micron Sizer LMS-2000e" (manufactured by Seishin Enterprise Co., Ltd.), the measurement was performed in accordance with JIS Z8825. .. For sample preparation, two tablespoons of microspartel iron powder was added to 120 mL of isopropyl alcohol, and ultrasonic treatment was performed for 1 minute to perform dispersion treatment. Subsequently, after demagnetization treatment using Magnetouch (TRUSCO NAKAYAMA, model MT-F), the sample was placed in a dispersion layer and the average particle size of iron powder was measured by a circulation method. The average particle size of the iron powder was defined as the volume average diameter. The maximum particle size was set to the value of d (90) (cumulative 90% particle size).

(4) Oxygen absorption amount The oxygen absorption amount was measured as follows.
A test piece, 3 g of cotton wool impregnated with 10 mL of water, a humidity control agent, and 500 mL of air were placed in an aluminum laminated barrier packaging material and sealed. It was stored in an environment of 25 ° C., and the oxygen concentration (X%) in the aluminum laminated barrier packaging material after 3 days was measured. A zirconia type oxygen concentration meter manufactured by Yasushi Trading Co., Ltd. was used for the measurement, and the oxygen absorption amount was derived from the following formula. The area of the test piece used for measuring the oxygen absorption amount of the multilayer container of Example 1 was 200 cm ² , and the test piece used for measuring the oxygen absorption amount of the oxygen absorption layer sheet of the reference example and the reference comparative example. The area was 113 cm ² .
The multi-layer container used in Example 1 has two oxygen absorbing layers, an oxygen absorbing layer (B) and an oxygen absorbing layer (F), but the oxygen permeable layer (A) and the protective layer (G). , And the adhesive layer (C) and the adhesive layer (E) have the same material and the same thickness, so the amount of oxygen absorbed in this test is the oxygen permeable layer (A) / oxygen absorbing layer (B). The area of the multilayer sheet composed of / the adhesive layer (C) / the gas barrier layer (D) is the same as that of ^{400 cm 2.}
Oxygen absorption (mL) = 500 x 0.205-{(500 x 0.795 x X) ÷ (100-X)}

<Manufacturing of polyamide resin>
Manufacturing example 1
(Manufacturing of Polyamide Resin X1)
15000 g (102.6 mol) of adipic acid (AdA) (manufactured by Asahi Kasei Co., Ltd.), isophthal in a 50 L reaction can with a jacket equipped with a stirrer, a condenser, a cooler, a thermometer, a dropping tank and a nitrogen gas introduction tube. Acid (IPA) (manufactured by AG International Chemical Co., Ltd.) was added so as to be 1088 g (6.6 mol), and hypophosphorous acid was added so that the phosphorus concentration was 300 ppm with respect to the polymer yield. Sodium monohydrate and sodium acetate were added so that the sodium concentration was 401 ppm with respect to the polymer yield. After sufficiently replacing the inside of the polymerization apparatus with nitrogen, the temperature was further raised to 170 ° C. under a nitrogen stream to bring the dicarboxylic acid into a fluid state, and then methylylenediamine (MXDA) (manufactured by Mitsubishi Gas Chemical Company, Inc.) 14792 g (108. 6 mol) was added dropwise with stirring. During this period, the internal temperature was continuously raised to 245 ° C., and the water distilled out with the dropping of m-xylylenediamine was removed from the system through a condenser and a cooler. After the addition of m-xylylenediamine was completed, the internal temperature was continuously raised to 255 ° C., and the reaction was continued for 15 minutes. Then, the internal pressure of the reaction system was continuously reduced to 600 mmHg for 10 minutes, and then the reaction was continued for 40 minutes. During this time, the reaction temperature was continuously raised to 260 ° C. After completion of the reaction, a pressure of 0.2 MPa was applied to the inside of the reaction can with nitrogen gas, and the polymer was taken out as a strand from a nozzle at the bottom of the polymerization tank, cooled with water and cut to obtain a pellet of a polyamide resin.
The obtained pellets of the polyamide resin were dry-blended by adding 400 ppm of calcium stearate (manufactured by NOF CORPORATION) as a lubricant using a tumbler to obtain pellets of the polyamide resin X1. The obtained polyamide resin X1 had a relative viscosity of 2.7, a glass transition temperature (Tg) of 92 ° C., and a melting point (Tm) of 229 ° C.

<Manufacturing of multi-layer container>
Example 1
(Manufacturing of oxygen-absorbing resin composition)
-Oxygen scavenger composition Iron powder (average particle size 31.9 μm, maximum particle size 55 μm) is placed in a vacuum mixing dryer with a heating jacket, and 100 mass of iron powder is heated and dried under a reduced pressure of 130 ° C. and 10 mmHg. A granular oxygen scavenger composition in which calcium chloride was adhered to the surface of iron powder was sprayed by spraying 2 parts by mass of a mixed aqueous solution in which calcium chloride: water = 1: 1 (mass ratio) was mixed. Prepared.
-Calcium oxide-added resin composition pellet Next, using a 32 mmφ co-rotating twin-screw extruder, calcium oxide (average particle size 10 μm, maximum particle size 50 μm) and homopolypropylene (“Novatec PP” manufactured by Japan Polypropylene Corporation FY6 ”) was kneaded at a ratio of 50:50 (mass ratio), extruded into strands, cooled with a net belt with a blower, and cut with a strand cutter to obtain calcium oxide-added resin composition pellets.
-Similar to the antioxidant-added resin composition pellets, a phenolic antioxidant (“Irganox1330” manufactured by BASF, chemical name: 1,3,5-trimethyl-2) was used using a 32 mmφ co-rotating twin-screw extruder. , 4,6-Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene) and a phosphorus-based antioxidant (BASF "Irgafos 168", chemical name: Tris (2,4-di-) t-butylphenyl) phosphite) and homopolypropylene (“Novatec PP FY6” manufactured by Nippon Polypro Co., Ltd.) are kneaded at a ratio of 0.1: 0.1: 99.8 (mass ratio) to form a strand. After extruding and cooling with a net belt with a blower, it was cut with a strand cutter to obtain pellets of an antioxidant-added resin composition.
-Oxygen Absorbent Resin Composition Pellet Subsequently, using a 32 mmφ co-rotating twin-screw extruder, the oxygen scavenger composition, homopolypropylene (“Novatec PP FY6” manufactured by Nippon Polypro Co., Ltd.), and oxidation The calcium-added resin composition pellets and the antioxidant-added resin composition pellets are kneaded at a ratio of 60:36: 3: 1 (mass ratio), extruded into a strand shape, cooled with a net belt with a blower, and then with a strand cutter. It was cut to obtain oxygen-absorbing resin composition pellets.

(Manufacturing of multi-layer container)
Next, a multi-layer sheet forming apparatus consisting of a 40 mmφ first to fifth extruder, a feed block, a T-die, a cooling roll, and a sheet take-up machine was used to obtain a multi-layer sheet (deoxidizing multilayer body) of 4 types and 7 layers. .. The layer structure of the multilayer sheet is as follows: oxygen permeable layer (A) / oxygen absorbing layer (B) / adhesive layer (C) / gas barrier layer (D) / adhesive layer (E) / oxygen absorbing layer (F) / protective layer (G). ).
The following resins or resin compositions were supplied to the first to fifth extruders, respectively. The layers in the multilayer sheet formed by each resin and the resin composition are also described.

1st extruder; polyamide X1 obtained in Production Example 1 (gas barrier layer (D))
Second extruder: A dry blend of the oxygen absorbing resin composition and homopolypropylene (“Novatec PP FY6” manufactured by Japan Polypropylene Corporation) at a ratio of 50:50 (mass ratio) (oxygen absorbing layer (B)). And oxygen absorption layer (F))
-Third and fifth extruders: Homopolypropylene ("Novatec PP FY6" manufactured by Japan Polypropylene Corporation) and polypropylene-based white masterbatch containing 60% titanium oxide (manufactured by Tokyo Ink Co., Ltd.) at 90:10 ( Dry blended by mass ratio) (oxygen permeable layer (A) and protective layer (G))
-Fourth extruder; maleic anhydride-modified polypropylene ("Modic P604V" manufactured by Mitsubishi Chemical Corporation) (adhesive layer (C) and adhesive layer (E))

The inner layer side of the obtained sheet was heat-molded as the inner side of the container to obtain a multi-layer container of 4 types and 7 layers.
Table 1 shows the analysis results and evaluation results of the obtained multilayer container.
The total thickness of the multilayer container and the ratio of each layer were measured by cutting the multilayer container with a cutter and measuring the cross section thereof with an optical microscope. Specifically, the container thickness (total thickness) and the thickness of each layer were measured at each point for a total of 4 points, 2 points at the center of the side surface and 2 points at the center of the bottom surface of the multi-layer container, and all points were measured. The thickness ratio of each layer to the thickness was calculated, and the average value was calculated. The thickness ratio of each of the four measured points was within the range of ± 3% of the average value. The results are shown below.
・ Total thickness: 500 μm
-Ratio of each layer (%): Oxygen permeable layer (A) / oxygen absorbing layer (B) / adhesive layer (C) / gas barrier layer (D) / adhesive layer (E) / oxygen absorbing layer (F) / protective layer ( G) = 38/6 / 2.5 / 7 / 2.5 / 6/38

^{The "iron content per 1 cm 2} " in Table 1 was calculated as follows. First, the mass with the area of the sample piece used for measuring the oxygen absorption amount was measured. The area of the multi-layer sheet-shaped test piece used for the measurement was 400 cm ² (the same oxygen permeable layer, oxygen absorption layer, adhesive layer and gas barrier layer existed on both sides of the ^{200 cm 2 test piece), and the mass was 4.91 g.} It was. Next, the mass ratio of the oxygen absorbing layer to the entire test piece was calculated from the thickness of each layer of the test piece, the density of the materials constituting each layer, and the blending amount. The mass ratio of one oxygen absorbing layer to the entire test piece was 7.86%.
Since the iron powder content in the oxygen absorption layer of the test piece obtained in Example 1 is 30% by mass, ^{the iron content per 1 cm 2 of} the test piece is 0.00058 g / by substituting into the following formula. It was cm ^2.
(Iron content per 1 cm ² ) = [(mass of test piece) x (mass ratio of oxygen absorbing layer to the entire test piece) x (mass ratio of iron powder in oxygen absorbing layer (content))] / ( Area of test piece)

<Simple evaluation of oxygen absorption layer (B)>
Reference examples 1-3
As a simple evaluation of the oxygen absorbing layer (B) of the multilayer container, the oxygen absorbing resin composition and the iron powder were changed to iron powder having an average particle size of 86.0 μm, and the same as the oxygen absorbing resin composition. The oxygen-absorbing resin composition obtained in did. The thickness of the obtained sheet was measured with a thickness meter (Digimatic Indicator ID-H0560 manufactured by Mitutoyo Co., Ltd.).
Table 2 shows the analysis results and evaluation results of the obtained sheets.

As can be seen from Reference Example 1 and Reference Example 2 in Table 2, a constant amount is obtained by setting the average particle size of the iron powder and the ratio of the average particle size of the iron powder to the thickness of the oxygen absorbing layer within a predetermined range. It can be seen that the amount of oxygen absorbed by the iron is increased, and the multi-layer container having the main layer as the oxygen absorbing layer (B) is excellent in the amount of oxygen absorbed with a small amount of iron powder. Further, since the multi-layer container obtained in Example 1 has a low iron powder content, it not only has high oxygen absorption, but also has excellent appearance and moldability.

Claims (24)

An oxygen permeable layer (A) containing an oxygen permeable resin as a main component, an oxygen absorbing layer (B) composed of an oxygen absorbing resin composition containing iron powder and a thermoplastic resin, and an adhesive layer containing an adhesive resin as a main component. A multi-layer container having a layer structure of four or more layers in which (C) and a gas barrier layer (D) containing a gas barrier resin as a main component are laminated in this order from an inner layer to an outer layer.
The gas barrier resin contains a diamine unit containing 70 mol% or more of a metaxylylene diamine unit, an α, ω-linear aliphatic dicarboxylic acid unit of 4 to 20 carbon atoms, 85 to 96 mol%, and an aromatic dicarboxylic acid unit of 15 to 96 mol%. It is a polyamide resin (X) composed of a dicarboxylic acid unit containing 4 mol%, and is
A multi-layer container in which the average particle size of iron powder is 1 μm or more and less than 100 μm, and the thickness of the oxygen absorbing layer (B) is 0.5 to 1.5 times the average particle size of iron powder. When the thickness of the oxygen permeable layer (A) is 20 to 50% of the total thickness of the multilayer container and the thickness of the oxygen absorbing layer (B) is 1% or more and less than 10% of the total thickness of the multilayer container. The multi-layer container according to claim 1. The multilayer container according to claim 1 or 2, wherein the average particle size of the iron powder is 1 μm or more and less than 80 μm. The multilayer container according to any one of claims 1 to 3, wherein the average particle size of the iron powder is 1 μm or more and less than 50 μm. The multi-layer container according to any one of claims 1 to 4, wherein the content of iron powder in the multi-layer container is 0.3% by mass or more and less than 3% by mass. The multi-layer container according to any one of claims 1 to 5, wherein the thickness of the adhesive layer (C) is 0.1% or more and less than 3% of the total thickness of the multi-layer container. An adhesive layer (E) containing an adhesive resin as a main component is laminated on the outer layer of the gas barrier layer (D), and an oxygen absorbing resin containing iron powder and a thermoplastic resin is laminated on the outer layer of the adhesive layer (E). 1. The oxygen absorbing layer (F) made of the composition is laminated, and the thickness of the oxygen absorbing layer (F) is 1% or more and less than 10% of the total thickness of the multilayer container. The multilayer container according to any one of 6 to 6. The multi-layer container according to claim 7, wherein a protective layer (G) containing a thermoplastic resin as a main component is laminated on the outer layer of the oxygen absorbing layer (F). The multi-layer container according to any one of claims 1 to 8, which has a 7-layer structure. The thickness of the protective layer (G) is 30 to 40% of the total thickness of the multi-layer container, and the thickness of the oxygen absorbing layer (F) is 3% or more and less than 7% of the total thickness of the multi-layer container. , The multi-layer container according to claim 8 or 9. An adhesive layer (E) containing an adhesive resin as a main component is laminated on the outer layer of the gas barrier layer (D), and a protective layer (G) containing a thermoplastic resin as a main component is laminated on the outer layer of the adhesive layer (E). The multilayer container according to any one of claims 1 to 6, wherein is laminated. The multi-layer container according to any one of claims 1 to 11, wherein the thickness of the gas barrier layer (D) is 2 to 20% of the total thickness of the multi-layer container. The method according to any one of claims 1 to 12, wherein the mass ratio of iron powder to the thermoplastic resin (iron powder / thermoplastic resin) in the oxygen absorbing layer (B) is 5/95 to 50/50. Multi-layer container. The multilayer container according to any one of claims 1 to 13, wherein the thermoplastic resin used in the oxygen-absorbing resin composition in the oxygen-absorbing layer (B) is a resin containing polypropylene as a main component. The thermoplastic resin used in the oxygen-absorbing resin composition in the oxygen-absorbing layer (B) is a resin containing polypropylene as a main component, and has undergone a thermal history equal to or higher than the melting point of the resin at least once in the extruder. , The multilayer container according to any one of claims 1 to 13. The multilayer container according to any one of claims 1 to 15, wherein the oxygen permeable resin used for the oxygen permeable layer (A) is a polypropylene resin. The multilayer container according to any one of claims 8 to 16, wherein the thermoplastic resin used for the protective layer (G) is one or more selected from polypropylene resin, polyamide resin and polyester resin. The multi-layer container according to any one of claims 8 to 17, wherein the thickness of the protective layer (G) is 20 to 50% of the total thickness of the multi-layer container. The multilayer container according to any one of claims 1 to 18, wherein the thickness of the oxygen absorbing layer (B) is 0.85 to 1.2 times the average particle size of iron powder. The thickness of the oxygen permeable layer (A) is 30 to 40% of the total thickness of the multilayer container, and the thickness of the oxygen absorbing layer (B) is 3% or more and less than 7% of the total thickness of the multilayer container. The multilayer container according to any one of claims 1 to 19. The multilayer container according to any one of claims 1 to 20, wherein the average particle size of the iron powder is 1 μm or more and less than 40 μm. The multilayer container according to any one of claims 1 to 21, wherein the iron powder is used as an oxygen scavenger composition composed of iron powder and a metal halide. The multilayer container according to claim 22, wherein the oxygen scavenger composition has an average particle size of 0.05 to 0.2 mm. The multilayer container according to claim 22 or 23, wherein the oxygen scavenger composition is an oxygen scavenger composition in which the surface of iron powder is coated with a metal halide.