JP2011126552A - Multilayer plastic container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer plastic container having both water barrier properties, oxygen barrier properties and oxygen absorbing properties. <P>SOLUTION: The multilayer plastic container includes a polyolefin resin layer 11A, an oxygen barrier, oxygen absorbing resin layer 15, and a polyolefin resin layer 11B in this order, and the oxygen barrier, oxygen absorbing resin layer 15 is a polyamide resin layer containing at least one metal atom selected from transition metals of the VIII group of the element periodic table, manganese, copper and/or zinc, wherein the polyolefin resin layer is a polypropylene resin layer, the metal atom is cobalt, and the polyamide resin is a polyamide obtained by polycondensation reaction of a diamine component containing m-xylylenediamine as a main component and a dicarboxylic acid component containing adipic acid as a main component. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a multilayer plastic container, and more particularly to a multilayer plastic container having both a moisture barrier property, an oxygen barrier property, and an oxygen absorption property.

In the present specification, “ratio”, “part”, “%” and the like indicating the composition are based on mass unless otherwise specified, and the “/” mark indicates that they are integrally laminated.
“EVOH” is “saponified ethylene-vinyl acetate copolymer”, “PP” is “polypropylene”, “Ny” is “polyamide”, and “moisture barrier property” is “water vapor (humidity) barrier property” Abbreviations, functional expressions, common names, or industry terms.

(Background Art) Conventionally, many metal cans, glass bottles, and various plastic containers are used as packaging containers. However, the quality of foods, beverages, pharmaceuticals, etc. stored in packaging containers is mainly oxidized by oxygen, deteriorated or deteriorated, and taste is lost. It may lead to disposal. Therefore, it is better to store and store in a system with little or no oxygen.
Metal cans and glass bottle containers have been used as containers because oxygen permeation through the container wall is zero. However, although it does not permeate oxygen, it easily cracks and deforms, and is heavy and has problems in handling and distribution.
Therefore, plastic containers that are lightweight, have excellent impact resistance, and have good design properties are used for various applications. However, in a plastic container, oxygen easily permeates through the container wall, and the content of the permeated oxygen deteriorates or deteriorates. Therefore, a multilayer plastic including a layer of saponified ethylene-vinyl acetate copolymer with good oxygen barrier properties. Even as a container, the humidity dependency of oxygen permeability is large, and the oxygen barrier property is poor in a high humidity environment.
Even if a container having excellent oxygen barrier properties is used, the contents may be altered or deteriorated by oxygen remaining in the container. That is, there are two types of oxygen in the packaging container, oxygen existing from the time of packaging, such as the head space in the packaging container, and oxygen that penetrates the container wall and enters the interior after packaging. Is also important for the preservation of the contents.
In order to remove oxygen in the container, an oxygen absorbent is also used, but it is uncomfortable because it is enclosed with the contents. Various layered multilayer plastic containers containing oxygen absorbers have also been proposed. Furthermore, for example, dry foods such as coffee powder and laver have many contents that are extremely reluctant to moisture (moisture).
Therefore, a multilayer plastic container that contains food and drink that is extremely disliked from moisture (moisture) and easily loses its flavor even when oxidized by a slight amount of oxygen has a moisture barrier property, an oxygen barrier property, and an oxygen absorption property. It has been demanded.
In the present specification, the moisture barrier property includes the barrier property of water vapor (humidity).

JP 2002-137347 A Japanese Patent Laid-Open No. 04-211444 JP 2008-189893 A JP 2003-335378 A

(Prior Art) Conventionally, as an oxygen-absorbing package having an excellent ability to prevent oxygen absorption and permeation, the inner layer of the olefin resin / the first layer of the oxygen barrier resin / from the inside of the package to the outside of the package / One having a laminated structure of oxygen absorbing resin layer / cyclic olefin copolymer layer / second layer of oxygen barrier resin / olefin resin outer surface layer is known (for example, see Patent Document 1). However, the oxygen absorption layer and the oxygen permeation preventive layer are separate layers, and the preparation of the composition is complicated and consists of at least six layers. The production requires a special and expensive apparatus for film formation and molding. There is a disadvantage that it is expensive.
An oxygen barrier resin composition comprising EVOH and an oxidation catalyst is used as a composition that uses an ethylene-vinyl acetate copolymer saponified product (EVOH) having excellent oxygen barrier properties and is further excellent in oxygen barrier properties. (For example, refer to Patent Document 2). However, EVOH is highly dependent on humidity, and the oxygen barrier property decreases under high humidity. If waterproof resin is formed on both sides to prevent this, the adhesiveness between the layers is poor, so an adhesive resin layer is provided. There is a problem that it must be.
Furthermore, the oxygen permeability is 100 cc / m 2 · day · atm (20 μm) or less for a multilayer structure excellent in oxygen gas barrier property even under high humidity and having excellent peel strength and a packaging container comprising this multilayer structure. The resin (B) having an oxygen absorption rate of 0.001 cc / cm 2 · day (20 μm) or more is dispersed in the matrix made of the resin (A), and the resin (B) has a maximum cross section perpendicular to the longitudinal direction. What forms the rod-shaped structure whose average diameter is 1.0 micrometer or less is known (for example, refer patent document 3). However, there is a problem that the oxygen absorption rate is slow.
Furthermore, as a method for storing the resin composition over a long period of time without reducing the oxygen absorption capacity of the oxygen-absorbing polyamide resin composition, an oxygen absorption rate in which the oxygen absorption rate is at least twice that of the resin composition is used. There is known a method of filling and storing the resin composition in a storage container formed by combining a functional composition and an oxygen barrier material (see, for example, Patent Document 4). However, it is described that a known method can be used for the packaging material and the packaging container using the oxygen-absorbing polyamide resin composition, and various articles can be stored and stored in the packaging container. It is only general theory, and no specific layer structure is described.

  In order to solve the above-described problems, the present inventors have made extensive studies and have completed the present invention. The object is to provide a multilayer plastic container having both moisture barrier properties, oxygen barrier properties and oxygen absorption properties.

In order to solve the above-mentioned problems, the multilayer plastic container according to the invention of claim 1 of the present invention is composed of a polyolefin resin layer, an oxygen barrier and oxygen absorbing resin layer, and a polyolefin resin layer in order of layer structure. And the oxygen barrier and oxygen-absorbing resin layer is a polyamide resin layer containing one or more metal atoms selected from group VIII transition metals, manganese, copper and / or zinc of the periodic table It is what you did.
The multilayer plastic container according to the invention of claim 2 is characterized in that the polyolefin resin layer is a polypropylene resin layer, the metal atom is cobalt, and the polyamide resin is a diamine component mainly composed of metaxylylenediamine and adipine. The polyamide is obtained from a polycondensation reaction with a dicarboxylic acid component containing an acid as a main component.
The multilayer plastic container according to the invention of claim 3 is such that the form of the multilayer plastic container is a tube container, a blow molded container, or a biaxially stretched blow molded container.

  According to this invention of Claims 1-3, there exists an effect which has moisture barrier property, oxygen barrier property, and oxygen absorptivity.

It is sectional drawing which shows one Example of the container wall of the multilayer plastic container of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Nylon (registered trademark) is a registered trademark of polyamide, but it will be omitted many times since it comes many times.

(Multilayer Plastic Container) As shown in FIG. 1, the container wall of the multilayer plastic container 1 of the present invention is composed of a polyolefin-based resin layer 11A, an oxygen-barrier and oxygen-absorbing resin layer 15, and a polyolefin-based resin layer. 11B, and the oxygen-barrier and oxygen-absorbing resin layer 15 includes one or more metal atoms selected from Group VIII transition metals, manganese, copper and / or zinc in the periodic table of elements. It should be a polyamide resin layer. Preferably, the polyolefin resin layers 11A and 11B are polypropylene resin layers, the metal atom is a cobalt atom, and the polyamide resin is a diamine component mainly composed of metaxylylenediamine and adipic acid. A polyamide (abbreviated as nylon MXD6) obtained from a polycondensation reaction with a dicarboxylic acid component is used. Moreover, let the form of the multilayer plastic container 1 be a tube container, a blow molding container, or a biaxial stretch blow molding container.

  (Effect) According to the present invention, the oxygen barrier property and oxygen absorption resin layer 15 having excellent oxygen barrier properties and oxygen absorption properties are sandwiched between the polyolefin resin having excellent moisture barrier properties as the inner layer and the outer layer. Thus, the effect of having moisture barrier properties, oxygen barrier properties and oxygen absorption properties is exhibited.

  (Polyolefin resin) The material and thickness of the polyolefin resin 11A and the polyolefin resin 11B may be the same or different. The polyolefin resin 11A and the polyolefin resin 11B are collectively referred to as a polyolefin resin 11. The polyolefin-based resin 11 is made of a polyethylene-based, polypropylene-based, or cyclic polyolefin-based resin, a copolymer resin, a modified resin, a mixture (including alloy), or a plurality of layers containing these resins as main components. A laminated body may be sufficient. For example, low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear (linear) low density polyethylene (LLDPE), polypropylene (PP), ethylene-vinyl acetate copolymer ( EVA), ionomer resin, ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methacrylic acid copolymer (EMAA), ethylene-methyl methacrylate copolymer ( EMMA), ethylene-propylene copolymer (EP), cyclic polyolefins such as polymethylpentene, polybutene, and polynorbornene, and polyolefin resins such as polyethylene and polypropylene are made of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumar -The absence of oxalic acid and itaconic acid Modified acid-modified polyolefin resin, etc. can be applied by the sum carboxylic acid. These resins can be used alone or in combination.

  The polyolefin resin 11 may include, for example, film processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slip properties, mold release properties, flame retardancy, and antifungal properties as necessary. Various plastic compounding agents and additives can be added for the purpose of improving and modifying the properties, electrical properties, strength, etc., and the addition amount is from a very small amount to several tens of percent, Depending on the purpose, it can be added arbitrarily. In the above, as general additives, for example, coloring of lubricants, plasticizers, fillers, antistatic agents, antiblocking agents, crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, dyes, pigments, etc. An agent, etc. can be used, and further, a modifying resin or the like can be used.

  The thickness of the polyolefin-based resin 11 can be appropriately set within a range of usually about 5 to 800 μm, preferably 10 to 500 μm. If it is less than this range, the moisture barrier property is insufficient, and if the thickness exceeds this range, the quality becomes excessive and the moldability also deteriorates.

  (Polypropylene resin) The polyolefin resin 11 is preferably a polypropylene resin in terms of moisture barrier properties, moldability, and cost.

  (Oxygen barrier and oxygen-absorbing resin layer) As the oxygen barrier and oxygen-absorbing resin layer 15, the group VIII transition metal, manganese, copper and / or zinc in the periodic table of elements having the ability to absorb oxygen A polyamide resin layer containing one or more metal atoms selected from the above and having an oxygen barrier property is used.

  (Polyamide resin layer) As the polyamide constituting the oxygen barrier and oxygen absorbing resin layer 15, there are nylon (registered trademark) 6, nylon 66, nylon 666, nylon 610, nylon 6T, nylon MXD6 and the like. Preferably, it is polyamide which has nylon MXD6 which is excellent in oxygen absorption capability as a main component. Nylon MXD6 is obtained by polycondensation of a diamine component having metaxylylenediamine as a main component and a dicarboxylic acid component having adipic acid as a main component. Paraxylylenediamine, 1,3-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, 2,6-naphthalenedicarboxylic acid and the like may be copolymerized. Moreover, as a dicarboxylic acid component, what contains 50 mol% or more of adipic acid is preferable.

  The polyamide only needs to contain nylon MXD6. For example, polyamide such as nylon 6, nylon 66, nylon 666, nylon 610, nylon 6T, polyester such as polyethylene terephthalate or polybutylene terephthalate, polyethylene or polypropylene, etc. A resin such as polyolefin, polycarbonate, polystyrene, or thermoplastic elastomer may be added within a range that does not affect the performance. Further, the oxygen barrier and oxygen absorbing resin layer 15 has a pigment, a dye, a lubricant, a matting agent, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a nucleating agent, a plasticizer within a range not affecting the performance. Additives such as additives, flame retardants, antistatic agents, anti-coloring agents and anti-gelling agents, and additives and fillers such as clay, mica, glass fiber and zeolite may be added.

  (Metal Atom) One or more metal atoms selected from Group VIII transition metals of the Periodic Table of Elements, manganese, copper and / or zinc constituting the oxygen barrier and oxygen absorbing resin layer 15 are polyamides. By promoting the oxidation reaction, the oxygen absorption function of the polyamide is enhanced. The oxidation reaction of the polyamide with metal atoms involves the generation of radicals by extracting hydrogen atoms from the methylene chain adjacent to the polyamide arylene group, and oxygen molecules are added to the radicals to generate peroxy radicals. It is presumed to be a reaction of abstracting hydrogen atoms by oxy radicals.

  Examples of the compound containing a metal atom include a low-valent inorganic acid salt, organic acid salt, or complex salt of the metal atom. Examples of inorganic acid salts include halides such as chloride and bromide, sulfates, nitrates, phosphates, silicates, etc. Examples of organic acid salts include carboxylates, sulfonates, phosphonates, etc. it can. Also, transition metal complexes with β-diketone or β-keto acid ester can be used. From the viewpoint of the oxygen absorbing function, carboxylates, halides, and acetylacetonate complexes containing the above metal atoms are preferable, and stearates, acetates, and acetylacetonate complexes are more preferable. A metal atom containing a cobalt metal atom is preferable from the viewpoint of excellent oxygen absorption function.

  The concentration of the metal atoms contained in the oxygen barrier resin layer 15 is not particularly limited, but is preferably in the range of 1 to 10000 ppm. If it is less than this range, the oxygen absorbing function is insufficient. If this range is exceeded, oxygen absorption occurs during the production of the oxygen barrier and oxygen absorbing resin layer 15 composition, and the polyamide is oxidized and deteriorated.

  The method for producing the oxygen-barrier and oxygen-absorbing resin layer 15 is not particularly limited, but a method of melt-mixing the polyamide and the compound containing the metal atom, dissolving the metal catalyst compound in a solvent, or Examples thereof include a method of removing a solvent by mixing with a polyamide after forming a slurry.

  (Container) The form of the multilayer plastic container 1 of the present invention is a tube container, a blow molded container, or a biaxially stretched blow molded container. Preferably, a multi-layered preform is blown or biaxially stretched to form a bottle-shaped container.

  First, the polyolefin resin layer 11A, the oxygen barrier and oxygen absorbing resin layer 15, and the polyolefin resin layer 11B are adjusted to have a desired composition to obtain a composition. It is preferable that the polyolefin resin layer 11A and the polyolefin resin layer 11B have the same composition because two kinds of materials may be adjusted. The two or three kinds of compositions thus prepared are melted and injected into a preform injection mold as a two or three layers or three or three layers by a known injection molding method. Create a preform. The preform can be biaxially stretched and blown into a bottomed cylindrical biaxially stretched blow molded container (multilayer plastic container 1). The cross section of this biaxially stretched blow-molded container had a three-layer structure similar to the cross-sectional property of the preform. As the preform injection mold and the biaxial stretch blow mold, a general PET bottle mold can be used.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, it is not limited to this. In addition, except a solvent, each composition of each layer is a mass part of solid content conversion.

(Example 1) As the polyolefin resin layer 11A and the polyolefin resin layer 11B, the same composition was used and PP was used. Examples of the oxygen barrier and oxygen absorbing resin layer 15 include polyamide (nylon MXD) obtained by melt polycondensation of adipic acid and metaxylylenediamine, and cobalt stearate weighed so that the cobalt metal concentration is 4000 ppm. The mixture was mixed with a tumbler, melt-kneaded with a single screw extruder of 30 mmφ, extruded as a strand, cooled and pelletized to obtain a composition.
Weight (weight per unit area) of polyolefin resin layer 11A / oxygen barrier and oxygen absorbing resin layer 15 / polyolefin resin layer 11B in this order is 11A: 15: 11B = 1: 2: 1. About 17 g of the multilayer preform was integrally injection-molded, and was then blow-molded by known biaxial stretching to form a bottle having an internal volume of 500 ml, to obtain (Multilayer Plastic Container 1) of Example 1.

  (Comparative Example 1) A plastic container of Comparative Example 1 was obtained in the same manner as in Example 1 except that PET resin was used in a single layer as the resin for injection molding and the weight (also referred to as the basis weight) was about 26 g. .

  (Comparative Example 2) Examples except that PET, Ny (not including an oxygen absorber), and PET resin were used in this order in three layers as the resin for injection molding, and the weight (also referred to as the basis weight) was about 26 g. In the same manner as in Example 1, a plastic container of Comparative Example 2 was obtained.

  (Comparative Example 3) A plastic container of Comparative Example 3 was obtained in the same manner as in Example 1 except that a single layer of PPT resin was used as the resin for injection molding and the weight (also referred to as basis weight) was about 17 g. .

  (Comparative Example 4) Examples except that PP, Ny (not including an oxygen absorbent), and PP resin were used in this order in three layers as the resin for injection molding, and the weight (also referred to as the basis weight) was about 17 g. In the same manner as in Example 1, a plastic container of Comparative Example 4 was obtained.

  (Evaluation) The oxygen permeation amount, dissolved oxygen concentration, and water permeability were evaluated.

(Measurement method) The oxygen permeation amount was measured by measuring the oxygen permeation amount from the outside (atmospheric pressure) by substituting the inside of the container with nitrogen using a gas barrier test apparatus manufactured by MOCON. The unit is cc / m ² · day · atm. is there. The dissolved oxygen concentration is measured using a PreSens dissolved oxygen concentration measuring device, and a patch coated with a phosphor is applied to the inner surface of the container, and the attenuation phase difference is converted into a concentration. The unit is mg / L. The moisture permeation rate was measured by measuring the mass change after 60 days by storing a water-filled container in a thermostatic chamber at 22 ° C. using a balance, and the unit is%. All measurements are average values of n = 20 samples, and the results are shown in Table 1.

  (Evaluation Result) In Example 1, the oxygen permeability is 0.008 as an oxygen barrier index, the dissolved oxygen concentration is 3.2 as an oxygen absorptivity index, and the water permeation amount is 0.11 as a moisture barrier index. In addition, it has moisture barrier properties, oxygen barrier properties, and oxygen absorption properties. Comparative Examples 1-2, 4 and 4 had relatively good moisture barrier properties and oxygen barrier properties, but did not have oxygen absorbability. Comparative Example 3 had good moisture barrier properties but low oxygen barrier properties and no oxygen absorption properties.

(Industrial applicability)
As the main use of the multilayer plastic container of the present invention, the contents are foods and beverages that are extremely disliked from moisture (moisture) and easily lose their flavor even when oxidized by a slight amount of oxygen, for example, for packaging coffee powder or laver Can be used for However, it is not particularly limited as long as it is a use that requires a combination of moisture barrier properties, oxygen barrier properties, and oxygen absorption properties.

11, 11A, 11B: Polyolefin resin 15: Oxygen barrier and oxygen absorbing resin layer

Claims (3)

  The layer structure is composed of, in order, a polyolefin resin layer, an oxygen barrier and oxygen absorbing resin layer, and a polyolefin resin layer, and the oxygen barrier and oxygen absorbing resin layer is a group VIII transition of the periodic table of elements. A multilayer plastic container comprising a polyamide resin layer containing one or more metal atoms selected from metal, manganese, copper and / or zinc.   The polyolefin resin layer is a polypropylene resin layer, the metal atom is cobalt, and the polyamide resin is a composite of a diamine component mainly composed of metaxylylenediamine and a dicarboxylic acid component mainly composed of adipic acid. The multilayer plastic container according to claim 1, which is a polyamide obtained from a condensation reaction.   The multilayer plastic container according to claim 1, wherein the multilayer plastic container is a tube container, a blow molded container, or a biaxially stretched blow molded container.