JP2008001768A - Resin composition and multilayer structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material which exhibits good barrier properties irrespectively of humidity, exhibits good barrier properties even after subjected to thermal sterilization treatment such as boiling and retorting and is excellent in heat resistance and moldability and to provide a multilayer structure using the same. <P>SOLUTION: The polyamide resin composition comprises at least two components of a polyamide (A) containing aromatic rings in its skeleton and a reducible organic compound (B) and a multilayer structure having a barrier layer comprises the resin composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin composition excellent in gas barrier properties, heat resistance and moldability, and a multilayer structure using the same. Specifically, the present invention relates to a resin composition suitable for packaging foods, beverages, medicines, etc., particularly a resin composition having excellent gas barrier properties when boiled and retorted, and a multilayer structure using the resin composition.

Packaging materials used for packaging foods and beverages not only have functions such as strength, resistance to cracking, and heat resistance to protect the contents from various distributions, storage such as refrigeration and processing such as heat sterilization, Various functions are required, such as excellent transparency so that the contents can be confirmed. Furthermore, in recent years, oxygen barrier properties that prevent the entry of oxygen from the outside in order to suppress food oxidation, carbon dioxide barrier properties, and barrier properties against various fragrance components are also required.

Sheets and films made of polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, and aliphatic polyamides such as nylon 6, are not only transparent and excellent in mechanical properties, but also because they are easy to handle and process. Widely used for materials. However, since the barrier property against gaseous substances such as oxygen is inferior, there is a drawback that the oxidative deterioration of the contents is likely to proceed, and the aromatic component and carbon dioxide are easily permeated, so that the expiration date of the contents is shortened.
In addition, plastic containers (such as bottles) mainly composed of polyester such as polyethylene terephthalate (PET) are widely used for tea, fruit juice drinks, carbonated drinks and the like. The proportion of small plastic bottles in plastic containers is increasing year by year. Since the ratio of the surface area per unit volume increases as the bottle becomes smaller, the shelf life of the contents tends to be shorter when the bottle is made smaller. In recent years, beer plastic bottles, which are easily affected by oxygen and light, and hot sale of plastic bottled tea have been sold, and as the range of use of plastic containers has expanded, gas barrier properties for plastic containers have been further improved. Is required.

  For the purpose of improving the barrier property against gaseous substances such as oxygen, a film in which the thermoplastic resin is combined with a gas barrier resin such as vinylidene chloride, ethylene-vinyl alcohol copolymer or polyvinyl alcohol is used. However, although a film laminated with vinylidene chloride is excellent in gas barrier properties regardless of storage conditions, there is a problem that dioxins are generated when it is burned and the environment is polluted. Although ethylene-vinyl alcohol copolymer and polyvinyl alcohol do not have the above-mentioned environmental pollution problems, multilayer films using these as barrier layers have excellent gas barrier properties when stored in a relatively low humidity environment. However, if the stored contents are high in water activity or stored in a high humidity environment, and after filling the contents, heat sterilization such as so-called boil processing or retort processing is performed. The gas barrier property tends to be greatly reduced, and there is a problem that oxygen permeation into the content increases and a problem occurs in the storage stability of the content.

  On the other hand, many techniques for improving oxygen barrier properties of containers by absorbing oxygen have been disclosed. For example, a method for absorbing oxygen by reducing a reducible organic compound and then oxidizing it with oxygen is disclosed. (Refer to Patent Documents 1 and 2) According to this document, the oxygen barrier property can surely be improved under conditions of room temperature and low humidity. However, applicable resins are limited to polyolefins with low oxygen barrier properties, etc. Even if the initial oxygen barrier properties are good, the oxygen barrier properties deteriorate gradually when stored for a long time, and the contents are stored for a long time. Had a problem that could not. Further, even when a resin such as ethylene-vinyl alcohol having a high barrier property is used, the stored content is high in water activity, stored in a high humidity environment, or so-called after filling the content. When heat sterilization treatment such as boil treatment or retort treatment is performed, the gas barrier property is greatly lowered, and thus oxygen permeation into the content is increased, resulting in a problem in storage stability of the content. In addition, since resins such as ethylene-vinyl alcohol have poor heat resistance, there has been a problem that molding processability is poor.

By the way, as a material having excellent gas barrier properties, a xylylene group-containing polyamide obtained from a polycondensation reaction of xylylenediamine and an aliphatic dicarboxylic acid, particularly polyamide MXD6 obtained from metaxylylenediamine and adipic acid is known. Polyamide MXD6 is a material that not only exhibits low permeability to gaseous substances such as oxygen and carbon dioxide, but also has excellent heat resistance and molding processability, and is heat sterilized under high humidity, boil and retort treatment, etc. Even when the treatment is performed, it is a material in which the gas barrier property is hardly lowered. However, polyamide MXD6 may have inferior gas barrier properties under low humidity as compared with an ethylene-vinyl alcohol copolymer, and improvement has been demanded.
Japanese Patent No. 2922306 JP-T-2001-514131

  The object of the present invention is to solve the above-mentioned problems, have good barrier properties regardless of humidity, and have good barrier properties even when heat sterilization treatment such as boil treatment or retort treatment is performed, resulting in heat resistance and molding processability. An object is to provide an excellent material and a multilayer structure using the same.

  As a result of intensive studies, the present inventors have found that a polyamide resin composition comprising at least two components of a polyamide (A) containing an aromatic ring in the skeleton and a reducible organic compound (B) is not dependent on humidity. The present inventors have found that the barrier property is good, the barrier property is good even when heat sterilization treatment such as boil treatment and retort treatment is performed, and the heat resistance and molding processability are excellent.

  That is, the present invention relates to a polyamide resin composition comprising at least two components of a polyamide (A) having an aromatic ring in the skeleton and a reducible organic compound (B). The present invention also relates to a multilayer structure having a barrier layer made of the resin composition.

  According to the present invention, a gas composition having excellent gas barrier properties regardless of humidity, having good barrier properties even when subjected to heat sterilization treatment such as boil treatment and retort treatment, and having excellent heat resistance and molding processability is obtained. Therefore, the industrial significance of the present invention is great.

The polyamide resin composition of the present invention (hereinafter referred to as the polyamide resin composition (C)) comprises a diamine component containing 70% by mole or more of metaxylylenediamine and an α, ω-linear aliphatic having 4 to 20 carbon atoms. It is preferably composed of at least two components of a polyamide (A) obtained by polycondensation with a dicarboxylic acid component containing 50 mol% or more of a dicarboxylic acid and a reducible organic compound (B). In the polyamide resin composition (C), the polyamide (A) is preferably contained in an amount of 70 to 99.9% by weight, more preferably 80 to 99.5% by weight, still more preferably 90 to 99% by weight. is there.

The polyamide (A) used in the present invention contains an aromatic ring in the skeleton, and the aromatic ring may be derived from either an aromatic diamine or an aromatic dicarboxylic acid. As the polyamide (A), for example, polycondensation of a diamine component having an aromatic diamine as a main component and a dicarboxylic acid having an aromatic dicarboxylic acid as a main component, or a diamine component having an aromatic diamine as a main component. And a dicarboxylic acid component mainly composed of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, or a diamine component mainly composed of an aliphatic diamine and an aromatic dicarboxylic acid. Examples include, but are not limited to, polyamides obtained by polycondensation of dicarboxylic acids containing acid as a main component. These polyamides may be homopolymers or copolymers. The polyamide has high barrier performance and good heat resistance and molding processability. Polyamide (A) can be used by blending one or more resins.

Examples of diamine components that can be used in the present invention include tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2, Aliphatic diamines such as 2,4-trimethyl-hexamethylenediamine and 2,4,4-trimethylhexamethylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1, 3-diaminocyclohexane, 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminomethyl) decalin, bis (aminomethyl) Illustrate diamines having an aromatic ring such as alicyclic diamine such as licyclodecane, bis (4-aminophenyl) ether, paraphenylenediamine, metaxylylenediamine, paraxylylenediamine, bis (aminomethyl) naphthalene, and the like. However, it is not limited to these.

Examples of dicarboxylic acid components that can be used in the present invention include carbon numbers such as aliphatic dicarboxylic acids such as succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, adipic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid. 4-20 α, ω-linear aliphatic dicarboxylic acids; aromatic dicarboxylic acids exemplified by terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and the like can be exemplified, but the present invention is not limited thereto. Absent.
Furthermore, a small amount of monoamine or monocarboxylic acid may be added as a molecular weight regulator during the polycondensation of the polyamide.

Examples of the polyamide (A) that can be used in the present invention include poly (hexamethylene isophthalamide) (PA-6I), hexamethylene isophthalamide / hexamethylene terephthalamide copolymer (PA-6I / 6T), and poly (meta Examples include xylylene isophthalamide) (PA-MXDI), caprolactam / metaxylylene isophthalamide copolymer (PA-6 / MXDI), caprolactam / hexamethylene isophthalamide copolymer (PA-6 / 6I), and the like.

As the polyamide (A) that can be particularly preferably used in the present invention, in addition to the above, a diamine component mainly composed of metaxylylenediamine and an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms as a major component. And polyamide (E) obtained by polycondensation with a dicarboxylic acid component. Polyamide (E) has high barrier performance and good heat resistance and molding processability. Metaxylylenediamine is preferably contained in an amount of 70 mol% or more, more preferably 75 mol% or more, and still more preferably 80 mol% or more. The dicarboxylic acid component contains an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, preferably 50 mol% or more, more preferably 70 mol% or more, and further preferably 80 mol% or more. Examples of the α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms include succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, adipic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid. Although aliphatic dicarboxylic acid can be illustrated, adipic acid is preferable among these.

The production method of the polyamide (A) is not particularly limited, and is produced by a conventionally known method and polymerization conditions. A small amount of monoamine or monocarboxylic acid may be added as a molecular weight regulator during the polycondensation of the polyamide. For example, it is produced by a method in which a nylon salt composed of metaxylylenediamine and adipic acid is heated in the presence of water in a pressurized state and polymerized in a molten state while removing added water and condensed water. Further, it is also produced by a method in which metaxylylenediamine is directly added to molten adipic acid and polycondensed under normal pressure. In this case, in order to keep the reaction system in a uniform liquid state, metaxylylenediamine is continuously added to adipic acid, and during this time, the reaction system is raised so that the reaction temperature does not fall below the melting point of the generated oligoamide and polyamide. The polycondensation proceeds while warming.

  The polyamide (A) may be subjected to polycondensation by solid-phase polymerization after being produced by a melt polymerization method. The production method of the polyamide (A) is not particularly limited, and is produced by a conventionally known method and polymerization conditions.

The number average molecular weight of the polyamide (A) is preferably 18000 to 43500, more preferably 20000 to 30000. Within this range, the heat resistance and the molding process are good.

  A phosphorous compound can be added to the polyamide (A) in order to increase the processing stability during melt molding or to prevent the polyamide (A) from being colored. As the phosphorus compound, a phosphorus compound containing an alkali metal or an alkaline earth metal is preferably used. For example, an alkali metal or alkaline earth metal phosphate such as sodium, magnesium, calcium, hypophosphite, phosphorus Acid salts may be mentioned, but those using alkali metal or alkaline earth metal hypophosphites are particularly preferred because they are particularly excellent in the anti-coloring effect of polyamide. The density | concentration of a phosphorus compound is 1-500 ppm as a phosphorus atom, Preferably it is 350 ppm or less, More preferably, it is 200 ppm or less.

The reducible organic compound (B) that can be used in the present invention is preferably contained in the polyamide resin composition (C) in an amount of 0.1 to 30% by weight, more preferably 0.5 to 20% by weight. More preferably, it is 1 to 10% by weight.

The reducible organic compound (B) is treated so as to be reduced to a reducible form that can be oxidized by molecular oxygen, and the oxidation of the reduced organic compound occurs regardless of the irradiation of light or the presence of transition metals. It is. The reduction treatment described above can be performed by exposure to light having a certain intensity or wavelength, heating, gamma ray irradiation, corona discharge, electron beam irradiation, or the like. By applying the energy as described above to the reducible organic compound (B), the reducible organic compound (B) is excited and reduced by extracting electrons or hydrogen atoms from the molecule or other molecules or polymers. It is thought. Thereafter, the reduced organic compound is considered to react and oxidize with oxygen regardless of the irradiation of light and the presence of transition metals.

As the reducible organic compound (B), photoreducible pigments such as quinones and azo compounds, and carbonyl compounds having absorption in the UV spectrum can be preferably used. Of these, quinones are particularly preferred. Quinones are compounds in which two carbonyl groups (for example, a ketone structure) exist in a ring such as a benzene ring. For example, quinones such as benzoquinone, anthraquinone, and naphthoquinone, and these include hydroxyl group, methyl group, ethyl group, amino group. And quinone derivatives to which functional groups such as carboxy group and carboxyl group are added, and these quinones and derivatives thereof may be partially hydrogenated (hereinafter referred to as benzoquinones, anthraquinones, and naphthoquinones, respectively). Called). There is no restriction | limiting in particular in the kind, number, and position of a functional group. The benzoquinones, anthraquinones, and naphthoquinones may be dimers or trimers.

Examples of benzoquinones include 1,2-benzoquinone (o-benzoquinone), 1,4-benzoquinone (p-benzoquinone), 2-chloro-1,4-benzoquinone, 2,3-dichloro-5,6-dicyanobenzoquinone, 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone, 2,5-dichloro-1,4-benzoquinone, 2,6-dichloro-1,4-benzoquinone, 2,5-dihydroxy-1, 4-benzoquinone, 2,6-di-tert-butyl-1,4-benzoquinone, 3,5-di-tert-butyl-1,2-benzoquinone, 2,6-dibromo-N-chloro-1,4- Benzoquinoneimine, 2,6-dibromo-N-chloro-1,4-benzoquinone monoimine, 2,5-dimethyl-1,4-benzoquinone, 2,6-dimethylbenzoquino 2,6-dimethoxy-1,4-benzoquinone, tetrachloro-1,4-benzoquinone, tetrachloro-1,2-benzoquinone, tetrahydroxy-1,4-benzoquinone, tetrafluoro-1,4-benzoquinone, N 2,6-trichloro-1,4-benzoquinone monoimine, trimethyl-1,4-benzoquinone, phenyl-1,4-benzoquinone, 1,4-benzoquinone dioxime, methyl-1,4-benzoquinone and the like. However, it is not limited to these.

Anthraquinones include anthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, dihydroxyanthraquinone, trihydroxyanthraquinone, 1,2,3,4-tetrahydroanthraquinone, 1,4,4a, 9a-tetrahydroanthraquinone, hexahydroanthraquinone, 1-aminoanthraquinone, 1-amino-4-hydroxyanthraquinone, anthraquinone-2,6-disulfonic acid disodium salt, anthraquinone-1-sodium sulfonate, anthraquinone-2-sodium sulfonate monohydrate, 1-chloroanthraquinone, 2-chloroanthraquinone, 1,4-diaminoanthraquinone, 1,5-dichloroanthraquinone, 1,5-dihydroxyanthraquinone, 1,8-dihydroxyanthraquino 1,4-dihydroxyanthraquinone, 4,5-dihydroxyanthraquinone-2-carboxylic acid, 1,4-dimethylanthraquinone, 1,2,4-trihydroxyanthraquinone, 2- (hydroxymethyl) anthraquinone, 2-tert-butyl Although anthraquinone etc. are mentioned, it is not limited to these.

As naphthoquinones, 1,2-naphthoquinone, 1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2 -Methyl-1,4-naphthoquinone, 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, sodium 1,2-naphthoquinone-4-sulfonate However, it is not limited to these.

The reducible organic compound (B) is preferably selected from benzoquinones, anthraquinones and naphthoquinones. The reducible organic compound (B) is more preferably selected from partially hydrogenated benzoquinones, anthraquinones and naphthoquinones, and benzoquinones having functional groups, anthraquinones and naphthoquinones. Further, the reducible organic compound (B) is more preferably selected from partially hydrogenated benzoquinones, anthraquinones and naphthoquinones having a functional group. Furthermore, the reducible organic compound (B) is particularly preferably selected from tetrahydroanthraquinone, hexahydroanthraquinone, tetrahydroanthraquinone having a functional group and hexahydroanthraquinone having a functional group. These quinones show an interaction not seen in other polymers in the exchange of electrons etc. due to the common term that they have a benzene ring with polyamide (A) having an aromatic ring in the skeleton, and other polymers It is considered that better oxygen absorbability is exhibited.

There is no restriction | limiting in particular in the blending method of polyamide (A) and a reducible organic compound (B), and it can mix by a well-known method. For example, dry blending may be performed using a tumbler or the like, melt blending may be performed by a single screw extruder, a twin screw extruder, or the like, and a master batch may be made by melt blending. Alternatively, the reducible organic compound (B) may be added during the polymerization of the polyamide (A).

In addition, the polyamide resin composition (C) can be blended with one or more other resins such as polyester, polyolefin, phenoxy resin and the like within a range that does not impair the purpose. In addition, inorganic fillers such as glass fibers and carbon fibers; plate-like inorganic fillers such as glass flakes, talc, kaolin, mica, montmorillonite, and organized clay; impact modifiers such as various elastomers; crystal nucleating agents ; Lubricants such as fatty acid amides, fatty acid metal salts, fatty acid amides; copper compounds, organic or inorganic halogen compounds, hindered phenols, hindered amines, hydrazines, sulfur compounds, phosphorus compounds, etc. Agents: Thermal stabilizers, anti-coloring agents, UV absorbers such as benzotriazoles, release agents, plasticizers, coloring agents, flame retardants and other additives, compounds containing cobalt metal which is a compound that imparts oxygen scavenging ability Further, additives such as alkali compounds for the purpose of preventing gelation of polyamide can be added.

In the present invention, when the polyamide resin composition (C) is used as a barrier layer of a multilayer structure, gas barrier properties and moldability are good and preferable. As a multilayer structure, a multilayer film, a multilayer sheet, a multilayer bottle, a multilayer blow bottle, etc. can be illustrated.

There is no restriction | limiting in particular about the manufacturing method of the multilayered structure of this invention, A well-known technique can be used. For example, after forming a film by a coextrusion method, it can be processed into various containers. As the coextrusion method, a known method such as a T-die method or an inflation method can be used. Moreover, after manufacturing a multilayer preform by injection molding, it can be blow-molded into a multilayer bottle.

  The multilayer structure of the present invention can be used as a four-side sealed bag, various types of pillow bags, bag-like containers such as standing pouches, various packaging materials such as container lids, bottles, and the like. Furthermore, a container can also be manufactured after manufacturing a stretched film by using a multilayer film as an original fabric. A multilayer unstretched film can be thermoformed into a cup-shaped container. Further, it may be laminated with paper to form a multilayer structure. Various articles can be stored and stored in the multilayer structure of the present invention. For example, carbonated drinks, juice, water, milk, sake, whiskey, shochu, coffee, tea, jelly drinks, health drinks and other liquid drinks, seasonings, sauces, soy sauce, dressings, liquid dashi, mayonnaise, miso, grated spices Seasonings such as jams, creams, chocolate pastes and other paste-like foods, liquid soups, boiled foods, pickles, stewed and other liquid processed foods such as buckwheat noodles, noodles, ramen and other raw noodles and boiled noodles , Representatives of pre-cooked rice such as polished rice, moistened rice, and non-washed rice, cooked cooked rice, processed rice products such as gomoku rice, red rice, rice bran, powdered soup, and powdered seasonings such as dashi stock High-moisture foods, dairy products such as cheese and yogurt, other solid and solution chemicals such as pesticides and insecticides, liquid and paste pharmaceuticals, lotions, cosmetic creams, and cosmetic emulsions Hair dressing, it is possible to house a hair dye, shampoo, soap, detergent or the like, various articles.

  In particular, the multilayer structure of the present invention is used as a material for packaging containers that contain articles with high water activity, packaging containers that are exposed to high humidity, and packaging containers that are subjected to heat sterilization treatment such as retort and boiling. It is suitable.

The multilayer structure of the present invention has at least one layer (layer (2)) other than the barrier layer (layer (1)). There is no restriction | limiting in particular as a material which comprises a layer (2), For example, polyester, polyolefin, polyamides, polystyrene, paper etc. are mentioned.

The layer (2) is preferably a layer mainly composed of polyester (hereinafter referred to as polyester (D)). The polyester (D) is obtained by polymerizing a dicarboxylic acid component in which 80 mol% or more, preferably 90 mol% or more is terephthalic acid, and a diol component in which 80 mol% or more, preferably 90 mol% or more is ethylene glycol. Is a thermoplastic polyester resin obtained.

  As the polyester (D), polyethylene terephthalate is preferably used. Polyethylene terephthalate is preferable because it exhibits excellent properties in transparency, mechanical strength, injection moldability, stretch blow moldability, and the like.

  Other dicarboxylic acid components other than terephthalic acid in (D) in polyester include isophthalic acid, diphenyl ether-4,4-dicarboxylic acid, naphthalene-1,4 or 2,6-dicarboxylic acid, adipic acid, sebacic acid, decane -1,10-carboxylic acid, hexahydroterephthalic acid and the like can be used. As other diol components other than ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis ( 4-hydroxyethoxyphenyl) propane or the like can be used. Furthermore, oxyacids, such as p-oxybenzoic acid, can also be used as a raw material monomer for polyester (D).

  The intrinsic viscosity of the polyester (D) is 0.55 to 1.30, preferably 0.65 to 1.20. When the intrinsic viscosity is 0.55 or more, the multilayer preform can be obtained in a transparent amorphous state, and the mechanical strength of the resulting multilayer bottle is also satisfied. When the intrinsic viscosity is 1.30 or less, bottle molding is easy without impairing fluidity during molding.

  In the range which does not impair the characteristic of this invention, other thermoplastic resins and various additives can be mix | blended and used for the said polyester (D). Examples of the thermoplastic resin include thermoplastic polyester resins such as polyethylene-2,6-naphthalenedicarboxylate, polyolefin resins, polycarbonate, polyacrylonitrile, polyvinyl chloride, polystyrene, and the like. Examples of the additive include an ultraviolet absorber, an oxygen absorber, a colorant, and an infrared absorber (reheat additive) for accelerating the heating of the preform and shortening the cycle time during molding.

For the layer (2), polyamides can be preferably used, and aliphatic polyamides are particularly preferably used since the mechanical properties can be improved without impairing the appearance of the film. As the aliphatic polyamide resin, copolymers such as nylon 6, nylon 66, nylon 46, nylon 610, nylon 612, nylon 11, nylon 12, nylon 666 and the like can be used alone or in combination. Among these, nylon 6, nylon 66, and nylon 666 are preferably used because they have a high effect of improving the mechanical properties of the film. The layer (2) is preferably a layer mainly composed of aliphatic polyamide.

In the layer (2), since the mechanical properties of the multilayer structure can be improved, for example, polyethylenes such as low density polyethylene, medium density polyethylene, and high density polyethylene, propylene homopolymer, propylene-ethylene block copolymer, propylene-ethylene Polypropylenes such as random copolymers, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, propylene-α-olefin copolymer Various polyolefins such as a polymer, polybutene, polypentene, and ionomer resin can be preferably used. The layer (2) is preferably a layer mainly composed of polyolefins.

In the multilayer structure of the present invention, an adhesive resin layer made of a modified polyolefin resin or the like may be laminated between the respective layers as necessary.

  In order to further improve the physical properties of the layer (2), impact modifiers such as various elastomers can be added. Furthermore, crystal nucleating agents, fatty acid amides, fatty acid metal salts, fatty acid amides can be added. Lubricants, copper compounds, organic or inorganic halogen compounds, hindered phenols, hindered amines, hydrazines, sulfur compounds, sodium hypophosphite, potassium hypophosphite, calcium hypophosphite, hypophosphorous acid Antioxidants such as phosphorus compounds such as magnesium acid, heat stabilizers, anti-coloring agents, UV absorbers such as benzotriazoles, release agents, plasticizers, coloring agents, additives such as flame retardants, titanium oxide, etc. Organic pigments such as inorganic pigments and dyes may be included.

The multilayer structure of the present invention may be laminated with a layer having a role of a sealant when used as a packaging material such as a pouch or a lid. The thermoplastic resin that can be used as a sealant is not particularly limited as long as it can exhibit the role as a sealant. For example, polyethylenes such as low density polyethylene, medium density polyethylene, and high density polyethylene, propylene homopolymer, propylene -Polypropylenes such as ethylene block copolymer, propylene-ethylene random copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer Polyolefins such as polymers, propylene-α-olefin copolymers, polybutene, polypentene, and ionomer resins, polyester resins such as polystyrene and polyethylene terephthalate, and heat peelable with easy peel properties Sexual resins. The sealant layer may be a single layer made of the above resin or may have a multilayer structure of two or more layers. In the case of a multilayer structure, an adhesive resin layer made of a modified polyolefin resin or the like may be laminated between the resin layers as necessary.

  For the sealant layer, impact modifiers such as various elastomers, crystal nucleating agents, fatty acid amides, fatty acid metal salts, fatty acid amides, and other lubricants, copper compounds, as long as the ability as a sealant is not impaired , Organic or inorganic halogen compounds, hindered phenols, hindered amines, hydrazines, sulfur compounds, phosphorous compounds such as sodium hypophosphite, potassium hypophosphite, calcium hypophosphite, magnesium hypophosphite, etc. Antioxidants, heat stabilizers, anti-coloring agents, UV absorbers such as benzotriazoles, release agents, additives such as plasticizers, coloring agents, flame retardants, organic pigments such as inorganic pigments and dyes such as titanium oxide A pigment may be included.

Furthermore, for the purpose of improving mechanical properties and commercial properties, the multilayer structure of the present invention may be laminated with an unstretched or stretched film made of polyester, polyamide, polypropylene or the like by extrusion lamination, dry lamination, or the like.

A multilayer bottle can be illustrated as a multilayer structure of this invention. The multi-layer bottle is formed by using, for example, an injection molding machine having two injection cylinders to transfer polyester (D) and polyamide resin composition (C) from the injection cylinders on the skin side and core side through the mold hot runner. The multilayer preform obtained by injection into the cavity is obtained by further biaxially stretching blow molding by a known method.

In general, blow molding of a multilayer preform includes conventionally known methods such as a so-called cold parison method and a hot parison method. For example, the surface of the multilayer preform is stretched in the axial direction by mechanical means such as heating to 80 to 120 ° C. and then pressing with a core rod insert, and then normally 2 to 4 MPa of high pressure air is blown and stretched in the transverse direction. For example, a method of molding, a method of crystallizing the mouth portion of the multilayer preform, heating the surface to 80 to 120 ° C., and then blow-molding in a mold of 90 to 150 ° C.

In the present invention, the preform heating temperature is preferably 90 to 110 ° C, more preferably 95 to 108 ° C. Within this range, the moldability is good.

In the present invention, since the barrier property, moldability, etc. are excellent, the multilayer bottle has a three-layer structure of polyester (D) layer / barrier layer / polyester (D) layer, or polyester (D) layer / barrier layer / polyester ( It is preferable to have a five-layer structure of D) layer / barrier layer / polyester (D) layer.

A multilayer bottle having a three-layer structure or a five-layer structure can be obtained by further biaxially stretching blow-molding a multilayer preform having a three-layer structure or a five-layer structure by a known method. There is no particular limitation on the method for producing a multilayer preform having a three-layer structure or a five-layer structure, and a known method can be used. For example, in the step of injecting the polyester (D) constituting the innermost layer and the outermost layer from the skin side injection cylinder, and injecting the resin constituting the barrier layer from the core side injection cylinder, first, the polyester (D) is injected, Next, the resin constituting the barrier layer and the polyester (D) are injected at the same time, then the required amount of polyester (D) is injected to fill the mold cavity, thereby forming a three-layer structure (polyester (D) layer / barrier layer / A multilayer preform (polyester (D) layer) can be produced.

Further, in the step of injecting the polyester (D) constituting the innermost layer and the outermost layer from the skin side injection cylinder, and injecting the resin constituting the barrier layer from the core side injection cylinder, first the polyester (D) is injected, and then By injecting the resin constituting the barrier alone and finally injecting the polyester (D) to fill the mold cavity, a five-layer structure (polyester (D) layer / barrier layer / polyester (D) layer / barrier) A multilayer preform of layer / polyester (D) layer can be produced.
The method for producing the multilayer preform is not limited to the above method.

  The thickness of the polyester (D) layer in the multilayer bottle is preferably 0.01 to 1.0 mm, and the thickness of the barrier layer is preferably 0.005 to 0.2 mm (5-200 μm). . Moreover, the thickness of a multilayer bottle does not need to be constant throughout the bottle, and is usually in the range of 0.2 to 1.0 mm.

  In the multilayer bottle, the weight of the barrier layer is preferably 1 to 20% by weight, more preferably 2 to 15% by weight, and particularly preferably 3 to 10% by weight based on the total weight of the multilayer bottle. By setting the weight of the barrier layer in the above range, a multilayer bottle having good gas barrier properties can be obtained, and molding from a precursor, which is a precursor, into a multilayer bottle is facilitated.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The polyamide resin composition and the multilayer structure were evaluated by the following method. Regarding the polyamide resin composition, the gas barrier properties of the single layer film were evaluated.
<Gas barrier properties>
(1) A single-layer film, a multilayer film, and a multilayer bottle are irradiated with light from a fluorescent lamp immediately before measurement, and the reducible organic compound (B) is reduced, and then 23 ° C., 50% according to ASTM D3985. The oxygen transmission rate was measured under an atmosphere of RH. Moreover, the oxygen transmission coefficient was computed about the single layer film. The measurement used Modern Controls make and OX-TRAN 2/61. The lower the value, the better the gas barrier property.
(2) The oxygen permeability of the cup after cup retorting was measured according to ASTM D3985 in an atmosphere of 23 ° C., internal 100% RH, external 50% RH. Further, the cumulative amount of oxygen permeating into the container was calculated. The measurement used Modern Controls make and OX-TRAN 2/61. The lower the value, the better the oxygen barrier property. At this time, the reduction treatment of the reducible organic compound (B) is performed by heat during retorting.

<Reference example>
(1) Synthesis of 2-methyl-1,4,4a, 9a-tetrahydroanthraquinone
Using the Diels-Alder reaction, it was synthesized by the following method.
After 1,4-naphthoquinone and ethanol were charged into the flask, isoprene was additionally charged into the flask. The temperature was raised with stirring, and refluxed for 5 hours to complete the reaction. After cooling for 12 hours, a crude product was obtained by filtration. The obtained crude product was recrystallized with ethanol and purified to obtain 2-methyl-1,4,4a, 9a-tetrahydroanthraquinone (hereinafter abbreviated as MTAQ).
(2) Synthesis of 2-methyl-1,2,3,4,4a, 9a-hexahydroanthraquinone 10% of 2-methyl-1,4,4a, 9a-tetrahydroanthraquinone synthesized in (1) above and toluene The flask was charged with a supported Pd / C catalyst. The flask was purged with nitrogen and heated to about 50 ° C. with stirring. Hydrogen was bubbled and hydrogenation reaction was performed. After the reaction, the hydrogen supply was stopped and bubbled with nitrogen for 10 minutes. Thereafter, the contents were filtered to obtain a crude product. From the resulting crude product, toluene as a solvent was removed by an evaporator to obtain 2-methyl-1,2,3,4,4a, 9a-hexahydroanthraquinone (hereinafter abbreviated as MHAQ).

<Example 1>
2-Methyl-9,10 anthraquinone (manufactured by Tokyo Chemical Industry Co., Ltd .: hereinafter abbreviated as MAQ) 1% by weight and polymetaxylylene adipamide (Mitsubishi Gas Chemical Co., Ltd. MX nylon S6007 solid phase polymerized product, number average molecular weight : 23500, relative viscosity (resin 1 g / 96% sulfuric acid 100 ml, measuring temperature 25 ° C.): 2.70, elastic modulus (ASTM D790 bending): 4.5 GPa) 99% by weight was dry blended with a tumbler, single screw extrusion Then, the film was extruded under the conditions of a barrel inlet temperature of 250 ° C. and a T-die temperature of 280 ° C. to obtain a 50 μm thick film. The evaluation results are shown in Table 1.

<Example 2>
MAQ 10% by weight and polymetaxylylene adipamide (Mitsubishi Gas Chemical Co., Ltd. MX nylon S6121 solid phase polymerized product, number average molecular weight: 40000, relative viscosity (resin 1 g / 96% sulfuric acid 100 ml, measuring temperature 25 ° C.): 94, elastic modulus (ASTM D790 bending): 4.5 GPa) 90 wt% is dry blended with a tumbler, supplied to a twin screw extruder, extruded into a strand at a barrel inlet temperature of 250 ° C, and then cut. Pellets were obtained and used as master batches. The obtained pellets were dried and crystallized at 150 ° C. under vacuum. The pellets and MX nylon S6007 were dry blended so that the MAQ was 2% by weight and extruded in the same manner as in Example 1 to obtain a single layer film having a thickness of 50 μm. The evaluation results are shown in Table 1.

<Example 3>
After polycondensation of metaxylylenediamine and adipic acid in a molten state until the relative viscosity of the polyamide becomes 2.30, an amount equivalent to 20% by weight of MTAQ is put inside the polymerization vessel, and after stirring, as a strand from the nozzle at the bottom of the polymerization tank After taking out and air-cooling, it was cut into pellets to obtain MTAQ-containing polymetaxylene adipamide. Thereafter, pellets solid-phase polymerized until the relative viscosity of the polyamide was 2.70 and MX nylon S6007 were dry blended so that the MTAQ was 3% by weight, extruded as in Example 1, and a single layer having a thickness of 50 μm. A film was obtained. The evaluation results are shown in Table 1.

<Example 4>
Using a multilayer film manufacturing apparatus consisting of two extruders, a feed block, a T die, a cooling roll, a take-up machine, etc., nylon 6 (made by Ube Industries, trade name UBE1020B, hereinafter abbreviated as N6) from the first extruder Was co-extruded from the second extruder in the same manner as in Example 2 above (forms a barrier layer), and N6 layer (10 μm) / barrier layer (5 μm) / N6 layer (10 μm) layer A two-layer three-layer multilayer film having a configuration was produced. The barrier layer was present uniformly, and the film could be stably formed. The evaluation results are shown in Table 1.

<Example 5>
Under the following conditions, a three-layer preform (27 g) composed of a polyester (D) layer / barrier layer / polyester (D) layer is injection molded, cooled, and then the preform is heated to perform biaxial stretch blow molding. Got a bottle. In addition, as a resin constituting the polyester (D) layer, polyethylene terephthalate (a mixed solvent having an intrinsic viscosity (phenol / tetrachloroethane = 6/4 (weight ratio), measuring temperature 30 ° C.)) of 0.75 (Japan) As a resin constituting the barrier layer using Unipet RT543C), MTAQ-containing polymetaxylene adipamide obtained in the same manner as in Example 3 and MX nylon S6007 were used, and the MTAQ concentration in the barrier layer was 2 What was dry blended so that it might become weight% was used. The barrier layer was present uniformly, a stable quality preform could be obtained, and the moldability was good. The weight of the barrier layer with respect to the total weight of the obtained multilayer bottle was 5% by weight. The oxygen permeability (23 ° C., 50% RH) of the multilayer bottle was 0.001 cc / day · 0.21 atm · package.

(Three-layer preform shape)
Total length 95mm, outer diameter 22mm, wall thickness 4.2mm. For the production of the three-layer preform, an injection molding machine (model: M200, 4 pieces) manufactured by Meiki Seisakusho Co., Ltd. was used.
(Three-layer preform molding conditions)
Skin side injection cylinder temperature: 280 ℃
Core side injection cylinder temperature: 260 ° C
Resin channel temperature in mold: 280 ° C
Mold cooling water temperature: 15 ° C

(Multilayer bottle shape)
Total length 223mm, outer diameter 65mm, inner volume 500ml, bottom shape is champagne type, body has no dimples. The biaxial stretch blow molding used a blow molding machine (model: EFB1000ET) manufactured by Frontier.
(Biaxial stretch blow molding conditions)
Preform heating temperature: 103 ° C
Stretching rod pressure: 0.5 MPa
Primary blow pressure: 1.0 MPa
Secondary blow pressure: 2.5 MPa
Primary blow delay time: 0.35 sec
Primary blow time: 0.28 sec
Secondary blow time: 2.0 sec
Blow exhaust time: 0.6 sec
Mold temperature: 30 ℃

<Example 6>
Using a multilayer sheet manufacturing apparatus equipped with 3 extruders, feed block, T die, cooling roll, winder, etc., polypropylene (from Nippon Polypro, trade name: Novatec PP, grade) from the first extruder Name: EC9, melt index: 0.5: hereinafter, abbreviated as PP) at 240 ° C. Adhesive resin (trade name; Admer, grade: QB550, manufactured by Mitsui Chemicals) from the second extruder is 230 ° C. From the third extruder, 2.5% by weight of MHAQ and 97.5% by weight of MX nylon S6007 were dry blended with a tumbler (forming a gas barrier layer) at 255 ° C., and PP was passed through a feed block. A multilayer sheet having a three-kind five-layer structure of layer / adhesive resin layer / gas barrier layer / adhesive resin layer / PP layer was produced. The thickness of each layer was 300/20/40/20/300 (μm).
Next, using a vacuum / pneumatic molding machine equipped with plug assist, when the sheet surface temperature reaches 170 ° C., thermoforming is performed, and the caliber is 62 mm × bottom diameter 52 mm × depth 28 mm, surface area 73 cm ² , volume 70 ml. A cup-shaped container was obtained.
Next, 70 ml of water is put in the container, and the opening is heat sealed with a film of PP / aluminum foil / PET = 50/9/12 (μm), and then sealed in an airtight container at 121 ° C. for 30 minutes using an autoclave. Was retorted. Next, after making a hole in the film and removing 60 ml of water, the gas introduction tube and the gas discharge tube were inserted, the insertion portion was sealed with an epoxy adhesive, and then sealed using an oxygen permeability measuring device. The transmittance was measured. The results are shown in Table 2.

<Comparative Example 1>
In the same manner as in Example 1, a single layer film comprising a single component of MX nylon S6007 was obtained. The evaluation results are shown in Table 1.

<Comparative example 2>
An ethylene-vinyl alcohol copolymer (Kuraray Co., Ltd., trade name: Eval, grade: F101B, melting point: 175 ° C.) alone component under the conditions of a barrel inlet temperature of 210 ° C. and a T-die temperature of 220 ° C. in the same manner as in Example 1. A monolayer film consisting of The evaluation results are shown in Table 1.

<Comparative Example 3>
Using multilayer sheet manufacturing equipment equipped with 3 extruders, feed block, T-die, cooling roll, winder, etc., PP (from Nippon Polypro Co., Ltd., trade name: Novatec PP, grade) Name: EC9, melt index: 0.5) at 220 ° C. Adhesive resin (Mitsui Chemicals, trade name: Admer, Grade: QF551) from the second extruder at 210 ° C. A blend of 97.5% by weight of an ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd., trade name: Eval, grade: F101B, melting point: 175 ° C.) and 2.5% by weight of MHAQ from an extruder (gas barrier layer Formed) at 220 ° C., and through a feed block, a multilayer sheet having three layers and five layers of PP layer / adhesive resin layer / gas barrier layer / adhesive resin layer / PP layer It was produced. The thickness of each layer was 300/20/40/20/300 (μm).
Next, using a vacuum / pressure forming machine equipped with plug assist, when the sheet surface temperature reaches 175 ° C., thermoforming is performed, and the diameter is 62 mm × bottom diameter 52 mm × depth 28 mm, surface area 73 cm ² , volume 70 ml. A cup-shaped container was obtained.
Next, 70 ml of water is put in the container, and the opening is heat sealed with a film of PP / aluminum foil / PET = 50/9/12 (μm), and then sealed in an airtight container at 121 ° C. for 30 minutes using an autoclave. Was retorted. Next, after making a hole in the film and removing 60 ml of water, the gas introduction tube and the gas discharge tube were inserted, the insertion portion was sealed with an epoxy adhesive, and then sealed using an oxygen permeability measuring device. The transmittance was measured. The results are shown in Table 2.

As shown in the above examples, the resin composition of the present invention and the multilayer structure using the resin composition have good barrier properties regardless of humidity, and are subjected to heat sterilization treatment such as boil treatment and retort treatment. The barrier properties were also good.

Claims (12)

A polyamide resin composition comprising at least two components of a polyamide (A) having an aromatic ring in the skeleton and a reducible organic compound (B). The reducible organic compound (B) is treated so as to be reduced to a oxidizable reduced form by molecular oxygen, and oxidation of the reduced organic compound occurs regardless of the irradiation of light or the presence of a transition metal. The resin composition according to claim 1, wherein: The resin composition according to claim 1 or 2, wherein the reducible organic compound (B) is selected from quinones, photoreducible pigments, and carbonyl compounds having absorption in the UV spectrum. The resin composition according to claim 1 or 2, wherein the reducible organic compound (B) is selected from benzoquinones, anthraquinones and naphthoquinones. The resin composition according to claim 1 or 2, wherein the reducible organic compound (B) is selected from partially hydrogenated benzoquinones, anthraquinones and naphthoquinones. The resin composition according to claim 1 or 2, wherein the reducible organic compound (B) is selected from partially hydrogenated benzoquinones, anthraquinones and naphthoquinones having a functional group. The resin composition according to claim 1 or 2, wherein the reducible organic compound (B) is selected from tetrahydroanthraquinone, hexahydroanthraquinone, tetrahydroanthraquinone having a functional group, and hexahydroanthraquinone having a functional group. . The polyamide (A) is a polycondensation of a diamine component containing 70 mol% or more of metaxylylenediamine and a dicarboxylic acid component containing 50 mol% or more of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. The resin composition according to any one of claims 1 to 7, wherein the resin composition is a polyamide obtained as described above. It has a barrier layer which consists of a resin composition of any one of Claims 1-8, The multilayer structure characterized by the above-mentioned. The multilayer structure of Claim 9 which has a layer mainly comprised by polyester (polyester (D)) as layers other than the said barrier layer. The multilayer structure according to claim 9, further comprising a layer mainly composed of polyolefin as a layer other than the barrier layer. The multilayer structure according to claim 9, comprising a layer mainly composed of aliphatic polyamide as a layer other than the barrier layer.