JP2008056766A - Resin composition and multiple layer-structured material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition and multiple layer-structured material excellent in gas barrier property under a high humidity, molding processability, productivity and transparency. <P>SOLUTION: This resin composition contains (A) a polyamide containing an aromatic ring in its backbone and (B) a component consisting of ≥1 kind selected from a specific fatty acid metal salt, a diamide compound, a diester compound, a nonionic surfactant, an anionic surfactant and a cationic surfactant. The multiple layer-structured material having a barrier layer consisting of the resin composition is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention has excellent barrier properties, regardless of molding conditions such as screw shape, temperature, back pressure, etc., less foaming during molding, improved productivity, and transparent regardless of molding conditions such as temperature and cooling time. The invention relates to a resin composition with improved properties and a multilayer structure using the same. Specifically, the present invention relates to a resin composition suitable for packaging foods, beverages, medicines, electronic parts and the like, 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, an 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, stored in a high-humidity environment, or further heat-sterilized after filling the contents, the gas barrier properties are greatly reduced. There is a problem that the storage stability of the contents is problematic.

  On the other hand, 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 shows low permeability to gaseous substances such as oxygen and carbon dioxide, but also has excellent heat resistance and molding processability, and is used in combination with various resins such as polyethylene terephthalate. Yes. However, when molding the polyamide MXD6, if the molding conditions such as screw shape, temperature, and back pressure are not set appropriately, air is entrained during the melt processing, and bubbles are generated in the barrier layer of the film, sheet, and bottle, Appearance defects such as silver stripes and uneven flow may occur. In particular, when the pellet contains a large amount of powder, these phenomena tend to increase, and improvement has been demanded.

In order to prevent air entrainment during the molding process, it is generally necessary to take measures such as cooling under the hopper, lowering the extruder cylinder temperature, lowering the screw speed, and increasing the back pressure in the case of injection molding. However, since the screw shape is poor even by these measures, air entrapment may not be sufficiently prevented, resulting in a problem that product yield deteriorates.
On the other hand, there has been disclosed a polyamide resin composition with good extrudability that can reduce discharge unevenness and reduce extruder power during melt extrusion molding (see Patent Document 1). According to this technique, extrudability can be improved at the time of extrusion molding. However, depending on the shape of the screw, air entrapment may not be prevented. Moreover, it was not a category about injection molding.

In addition, since polyamide MXD6 has crystallinity, if the molding conditions such as extrusion temperature, cooling temperature, and cooling time are not properly set, the product is crystallized and whitened immediately after molding, and the transparency of products using the same May decrease. In order to prevent whitening due to crystallization immediately after molding, it is possible to improve to some extent if the cooling temperature is lowered or the cooling time is lengthened, but the problem is that the cycle time increases and the economic efficiency deteriorates. It was. In addition, it is difficult to use polyamide MXD6 in an apparatus in which the cooling temperature cannot be sufficiently lowered due to the specifications of the apparatus or the cooling time cannot be extended.
On the other hand, a polyamide molded body made of solid phase polymerized polyamide MXD6, which is less likely to be whitened when stored under high humidity, in contact with water or boiling water, or when heated to a glass transition temperature or higher, is disclosed. (See Patent Document 2), however, was not in the category of prevention of crystallization immediately after molding or polyamide that was not solid-phase polymerized.
Japanese Patent Laid-Open No. 10-147711 JP 2000-248176 A I want to know injection molding Published by Japan Machinist

  The object of the present invention is to solve the above-mentioned problems, good barrier properties even under high humidity, and without depending on molding conditions such as screw shape, without generating bubbles not only during extrusion molding but also during injection molding, An object of the present invention is to provide a material with improved moldability and productivity, a material with improved transparency by preventing whitening due to crystallization immediately after molding, and a multilayer structure using the material.

  As a result of intensive studies, the inventors of the present invention comprise a polyamide (A) containing an aromatic ring in the skeleton, and a component (B) selected from a specific fatty acid metal salt, diamide compound, diester compound and surfactant. The present inventors have found that the resin composition is excellent in gas barrier properties under high humidity, molding processability, productivity, and transparency, and have reached the present invention.

  That is, the present invention provides a polyamide (A) having an aromatic ring in the skeleton, a fatty acid metal salt having 10 to 50 carbon atoms, a diamide compound obtained from a fatty acid having 8 to 30 carbon atoms and a diamine having 2 to 10 carbon atoms, carbon A component (B) comprising at least one selected from diester compounds obtained from fatty acids of several 8 to 30 and diols of 2 to 10 carbon atoms, nonionic surfactants, anionic surfactants and cationic surfactants It is related with the resin composition containing. The present invention also relates to a multilayer structure having a barrier layer made of the resin composition.

  According to the present invention, a resin composition and a multilayer structure excellent in gas barrier properties under high humidity and excellent in moldability, productivity, and transparency can be obtained. Therefore, the industrial significance of the present invention is great. .

The resin composition of the present invention (hereinafter referred to as the resin composition (D)) includes a polyamide (A) having an aromatic ring in the skeleton, a fatty acid metal salt having 10 to 50 carbon atoms, and a fatty acid having 8 to 30 carbon atoms. And diamide compounds obtained from diamines having 2 to 10 carbon atoms, diester compounds obtained from fatty acids having 8 to 30 carbon atoms and diols having 2 to 10 carbon atoms, nonionic surfactants, anionic surfactants and cationic interfaces It is preferable to contain the component (B) which consists of 1 or more types chosen from an activator. This polyamide (A) has good barrier properties and good gas barrier properties under high humidity.

The resin composition (D) has an oxygen transmission coefficient (OTR) of OTR (average value) ≦ 0.2 cc · mm / (m ² · day · atm) under the conditions of a temperature of 23 ° C. and a relative humidity of 60% RH. It is preferable to satisfy. The OTR is more preferably OTR ≦ 0.15 cc · mm / (m ² · day · atm), more preferably OTR ≦ 0.10 cc · mm / (m ² · day · atm), and particularly preferably OTR ≦ 0. 0.08 cc · mm / (m ² · day · atm) is satisfied. By using such a barrier layer exhibiting OTR performance, the gas barrier performance of the resulting bottle is improved, and the expiration date of the contents to be stored can be extended.

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. Examples of polyamide (A) include polycondensation of a diamine component mainly composed of aromatic diamine and a dicarboxylic acid component mainly composed of aromatic dicarboxylic acid, or a diamine component mainly composed of aromatic diamine. A polycondensation of a dicarboxylic acid component having an aliphatic dicarboxylic acid as a main component, or a polycondensation of a diamine component having an aliphatic diamine as a main component and a dicarboxylic acid component having an aromatic dicarboxylic acid as a main component However, this is not restrictive. 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 the diamine component that can be used in the production of the polyamide (A) include tetramethylene diamine, pentamethylene diamine, 2-methylpentane diamine, hexamethylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, and dodecamethylene. Aliphatic diamines such as diamine, 2,2,4-trimethyl-hexamethylenediamine, 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 (amino Aliphatic diamines such as methyl) tricyclodecane; diamines having an aromatic ring such as bis (4-aminophenyl) ether, paraphenylenediamine, metaxylylenediamine, paraxylylenediamine, bis (aminomethyl) naphthalene, etc. However, the present invention is not limited to these examples.

Examples of the dicarboxylic acid component that can be used for producing the polyamide (A) include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, adipic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid. An aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid or 2,6-naphthalenedicarboxylic acid can be exemplified, but is not limited thereto.

Examples of the polyamide (A) that can be used in the present invention include polyhexamethylene isophthalamide (PA-6I), hexamethylene isophthalamide / hexamethylene terephthalamide copolymer (PA-6I / 6T), and polymetaxylylene isophthalate. Examples include ramid (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 a polyamide obtained by polycondensation with a dicarboxylic acid component (hereinafter referred to as polyamide (E)). Polyamide (E) has high barrier performance and good heat resistance and molding processability. The diamine component contains metaxylylenediamine, preferably 70 mol% or more, more preferably 75 mol% or more, and still more preferably 80 mol% or more. The dicarboxylic acid component is preferably an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, preferably 70 mol% or more, more preferably 75 mol% or more, still more preferably 80 mol% or more, particularly preferably 90 mol. % Is included. 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.
A polyamide (E) containing 1 to 20 mol%, more preferably 3 to 10 mol% of isophthalic acid as a dicarboxylic acid component is also preferably used. By adding isophthalic acid as a dicarboxylic acid component, whitening immediately after molding can be further suppressed.

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 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 moldability are good.

The heat of fusion of the polyamide (A) used in the present invention is preferably 30 to 70 J / g. When it is within this range, melting of the resin in the extruder when mixed with the component (B) is facilitated, and there is little risk of entrainment of air during melting, resulting in good productivity and molding processability.

The glass transition temperature (Tgm) of the polyamide (A) used in the present invention is preferably 70 to 100 ° C. When it is within this range, melting of the resin in the extruder when mixed with the component (B) is facilitated, and there is little risk of entrainment of air during melting, resulting in good productivity and molding processability.

The crystallinity of the polyamide (A) used in the present invention is preferably 10 to 40%. When it is within this range, melting of the resin in the extruder when mixed with the component (B) is facilitated, and there is little risk of entrainment of air during melting, resulting in good productivity and molding processability. When the degree of crystallinity is too low, air is easily entrained, and when the degree of crystallinity is too high, melting takes time and the formability may deteriorate. Moreover, the whitening immediately after shaping | molding can be suppressed.

The semi-crystallization time of the polyamide (A) used in the present invention is preferably 20 to 1600 s at 160 ° C., more preferably 21 to 150 s. When it is within this range, melting of the resin in the extruder when mixed with the component (B) is facilitated, and there is little risk of entrainment of air during melting, resulting in good productivity and molding processability. Moreover, the whitening immediately after shaping | molding can be suppressed.

The melting point of the polyamide (A) used in the present invention is preferably 200 to 265 ° C. When it is within this range, melting of the resin in the extruder when mixed with the component (B) is facilitated, and there is little risk of entrainment of air during melting, resulting in good productivity and molding processability.

The melting point, heat of fusion, and glass transition temperature can be measured by DSC (Differential Scanning Calorimetry) method. For the measurement, for example, DSC-50 manufactured by Shimadzu Corporation can be used, the sample amount can be about 5 mg, and the heating rate can be measured by heating from room temperature to 300 ° C. under the condition of 10 ° C./min. The atmosphere gas was nitrogen at 30 ml / min. A so-called midpoint temperature (Tgm) was adopted as the glass transition point. As is widely known, Tgm is the midpoint temperature of the intersection of the tangent line of the baseline and the transition slope of the glass state and the supercooled state (rubber state) in the DSC curve. The crystallinity can be calculated using the heat of crystallization and the heat of fusion determined by the DSC method.
The half crystallization time can be determined by the depolarized intensity method. Specifically, polyamide (A) is melt-extruded by an extruder at 240 to 270 ° C., and a sheet having a thickness of about 100 to 200 μm obtained through a T-die is sandwiched between two glass plates, and at 280 ° C. After being melted in an air bath for 3 minutes, it can be obtained by putting it in a 160 ° C. oil bath and using a depolarized intensity method. As the apparatus, for example, one manufactured by Kotaki (polymer crystallization rate measuring apparatus MK-701) or the like can be used.

  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 fatty acid metal salt that can be used as the component (B) in the present invention is a fatty acid metal salt having 10 to 50 carbon atoms, more preferably 18 to 34 carbon atoms. Fatty acids may have side chains and double bonds, but linear saturated such as stearic acid (C18), eicosanoic acid (C20), behenic acid (C22), montanic acid (C28), triacontanoic acid (C30) Fatty acids are preferred. There are no particular restrictions on the metal that forms the salt with the fatty acid, but sodium, potassium, lithium, calcium, barium, magnesium, strontium, aluminum, zinc, cobalt, etc. are exemplified, and sodium, potassium, lithium, calcium, aluminum, and zinc Is particularly preferred. Of these, calcium stearate is particularly preferable.

  One type of fatty acid metal salt may be used, or two or more types may be used in combination. In the present invention, the particle diameter of the fatty acid metal salt is not particularly limited. However, the smaller the particle diameter, the easier it is to disperse uniformly, so the particle diameter is preferably 0.2 mm or less.

  The diamide compound that can be used as the component (B) in the present invention is obtained from a fatty acid having 8 to 30 carbon atoms and a diamine having 2 to 10 carbon atoms. When the fatty acid has 8 or more carbon atoms and the diamine has 2 or more carbon atoms, an effect of preventing whitening can be expected. Further, when the fatty acid has 30 or less carbon atoms and the diamine has 10 or less carbon atoms, uniform dispersion is good. The fatty acid may have a side chain or a double bond, but a linear saturated fatty acid is preferred.

  Examples of the fatty acid component of the diamide compound include stearic acid (C18), eicosanoic acid (C20), behenic acid (C22), montanic acid (C28), and triacontanoic acid (C30). Examples of the diamine component of the diamide compound include ethylenediamine, butylenediamine, hexanediamine, xylylenediamine, and bis (aminomethyl) cyclohexane. A diamide compound obtained by combining these is used in the present invention. A diamide compound obtained from a diamine composed mainly of a fatty acid having 8 to 30 carbon atoms and mainly ethylenediamine, or a diamide compound obtained from a fatty acid mainly composed of montanic acid and a diamine having 2 to 10 carbon atoms is preferred. Of these, ethylene bisstearylamide is particularly preferred.

  The diester compound that can be used as the component (B) in the present invention is obtained from a fatty acid having 8 to 30 carbon atoms and a diol having 2 to 10 carbon atoms. When the fatty acid has 8 or more carbon atoms and the diol has 2 or more carbon atoms, an effect of preventing whitening can be expected. Further, when the fatty acid has 30 or less carbon atoms and the diol has 10 or less carbon atoms, uniform dispersion in the mixed resin B is good. The fatty acid may have a side chain or a double bond, but a linear saturated fatty acid is preferred.

  Examples of the fatty acid component of the diester compound include stearic acid (C18), eicosanoic acid (C20), behenic acid (C22), montanic acid (C28), triacontanoic acid (C30) and the like. Examples of the diol component of the diester compound include ethylene glycol, propanediol, butanediol, hexanediol, xylylene glycol, and cyclohexanedimethanol. A diester compound obtained by combining these is used in the present invention. Particularly preferred are diester compounds obtained from fatty acids composed mainly of montanic acid and diols composed mainly of ethylene glycol and / or 1,3-butanediol.

  The diamide compound and the diester compound may be added with one or more diamide compounds, may be added with one or more diester compounds, or may be one or more diamides. You may use a compound and 1 type, or 2 or more types of diester compounds together.

In the present invention, a surfactant can be used as the component (B). As the surfactant, known substances such as nonionic surfactants, anionic (anionic) surfactants, and cationic (cationic) surfactants can be used. Nonionic surfactants include ester type, ether type, alkylphenol type polyethylene glycol type surfactants, sorbitan ester type polyhydric alcohol partial ester type surfactants, polyoxyethylene sorbitan ester type ester ether type surfactants. However, it is not limited to these. In the present invention, polyoxyethylene sorbitan monolaurate, which is a kind of ester ether surfactant of the polyoxyethylene sorbitan ester type, is preferably used because it has a particularly excellent air entrainment prevention effect and whitening prevention effect.

One type of component (B) may be used, or two or more types may be used in combination.
C10-C50 fatty acid metal salt, diamide compound obtained from C8-C30 fatty acid and C2-C10 diamine, C8-C30 fatty acid and diester obtained from C2-C10 diol When adding a compound as a component (B), 50-1000 ppm is preferable in a resin composition (D), 100-800 ppm is more preferable, 200-500 ppm is especially preferable. Within this range, the effect of preventing air entrainment and whitening is high, and the productivity and moldability are good.
When a nonionic surfactant, an anionic surfactant and a cationic surfactant are added as the component (B), the addition amount is preferably 50 to 500 ppm, more preferably 70 to 250 ppm in the resin composition (D). preferable. Within this range, the effect of preventing air entrainment and whitening is high, and the productivity and moldability are good.

  The component (B) in the present invention is preferably at least one selected from the fatty acid metal salts, diamide compounds, diester compounds and nonionic surfactants, more preferably from the fatty acid metal salts and nonionic surfactants. One or more selected. It is more preferable to use the fatty acid metal salt and a nonionic surfactant in combination, and it is particularly preferable to use calcium stearate and polyoxyethylene sorbitan monolaurate in combination.

When the fatty acid metal salt, diamide compound, diester compound, and nonionic surfactant are used in combination as the component (B) in the present invention, their added amount is in the resin composition (D),
The fatty acid metal salt, diamide compound and diester compound are preferably 100 to 1000 ppm, and the nonionic surfactant is preferably 50 to 200 ppm, more preferably the fatty acid metal salt, diamide compound and diester compound are 200 to 500 ppm and nonionic surfactant. The agent is 70 to 150 ppm.

The kinematic viscosity of the nonionic surfactant is preferably about 200 to 1000 mm ² / s at 25 ° C., more preferably about 250 to 500 mm ² / s. When the kinematic viscosity is within this range, the dispersibility is good, the effect of preventing air entrainment is high, and the productivity and moldability are good.

Each component (B) may be used alone, but when used in combination, the effect of preventing air entrainment is extremely high, and productivity and moldability are particularly good.

There is no restriction | limiting in particular in the mixing method of a component (B), It can mix by a well-known technique.

In addition, the resin composition (D) can be blended with one or more other resins such as polyester, polyolefin, phenoxy resin and the like within a range not impairing the purpose. In addition, fibrous 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, crystals 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. Antioxidants; heat stabilizers, anti-coloring agents, benzotriazole-based UV absorbers, mold release agents, plasticizers, coloring agents, flame retardants and other additives, and cobalt metal, a compound that imparts oxygen scavenging ability Additives such as an alkali compound for the purpose of preventing gelation of the compound to be contained and polyamide can be added.

In the present invention, when the resin composition (D) is used as a barrier layer of a multilayer structure, gas barrier properties, productivity, molding processability, and transparency are favorable. 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. In particular, when the resin composition (D) of the present invention is used as a barrier layer, when producing a multilayer preform by injection molding, the effect of preventing entrainment of bubbles and the effect of preventing whitening are high, and the productivity and transparency are good. preferable.

When the resin composition (D) is used as a barrier layer at the time of molding a multilayer structure, a known screw such as a so-called nylon or polyolefin, slow compression, rapid compression type, single flight, double flight or the like should be used as a screw. Even a screw that has been said to be unsuitable for the extrusion of MXD6 can be formed without entrainment of bubbles.

200-300 degreeC is preferable and, as for the cylinder temperature at the time of extrusion or injection molding of the said resin composition (D) as a barrier layer at the time of shaping | molding of a multilayer structure, 210-290 degreeC is more preferable. The screw rotation speed is preferably 5 to 400 rpm, more preferably 10 to 250 rpm. The back pressure during measurement during injection molding is preferably 0 to 1000 psi, and more preferably 25 to 500 psi.

  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. The polyester 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. It is preferably a thermoplastic polyester resin (hereinafter referred to as polyester (F)).

  As the polyester (F), 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.

  Examples of the dicarboxylic acid component other than terephthalic acid in the polyester (F) 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 and hexahydroterephthalic acid 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 of polyester (F).

  The intrinsic viscosity of the polyester (F) is 0.55 to 1.30, preferably 0.65 to 1.20, particularly preferably 0.7 to 1.0. 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 (F). 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. It is preferable to use the resin composition (D) as a barrier layer of the multilayer bottle because the growth of spherulites in the barrier layer can be suppressed and the delamination resistance of the multilayer bottle is improved. The multi-layer bottle uses, for example, an injection molding machine having two injection cylinders to transfer the polyester (F) and the resin composition (D) from the injection cylinders on the skin side and the core side through the mold hot runner. The multilayer preform obtained by injection into the tee can be 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 from the multilayer preform to the bottle is good. In addition, the measurement of surface temperature uses an infrared radiation thermometer, and emissivity can be measured on condition of 0.95 normally.

The weight of the multilayer preform is preferably 15 to 50 g. The pre-form for bottles of about 500 ml is preferably 18 g to 30 g, and the pre-form for bottles of about 350 ml is preferably 15 g to 25 g. Within this range, the moldability from the multilayer preform to the bottle is good, and the gas barrier property is good.

In the present invention, since the barrier property, moldability, etc. are excellent, the multilayer bottle has a three-layer structure of polyester (F) layer / barrier layer / polyester (F) layer, or polyester (F) layer / barrier layer / polyester ( F) It is preferable to have a five-layer structure of layer / barrier layer / polyester (F) 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. The cooling time for forming the multilayer preform is preferably 2 seconds or more, and more preferably 3 seconds or more. Moreover, it is preferable that cooling water temperature is 15 degrees C or less. 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 (F) 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 (F) is injected, Next, the resin constituting the barrier layer and the polyester (F) are injected at the same time, and then the required amount of polyester (F) is injected to fill the mold cavity, thereby forming a three-layer structure (polyester (F) layer / barrier layer / A multilayer preform of polyester (F) layer can be produced.

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

  The thickness of the polyester (F) 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 to 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.

  The bottom of the multilayer bottle is preferably a petaloid shape or a champagne shape.

  In a multi-layer bottle obtained by biaxial stretching blow molding of a multi-layer preform, gas barrier performance can be exhibited if at least the barrier layer is present in the body of the multi-layer bottle, but the barrier layer extends to the vicinity of the top end of the multi-wall bottle stopper. The gas barrier performance is even better when the is extended. In addition, the draw ratio when it shape | molds from a preform to a bottle is about 9 to 13 times in general.

  In the present invention, the multilayer bottle can be heat set (heat-fixed) in a blow mold. Heat setting can be performed under conventionally known conditions. For example, the mouth of the multilayer preform is first crystallized by infrared heating, and the mold temperature is preferably 130 to 180 ° C, more preferably 145 to 165 ° C. , Preferably 1 to 20 seconds, more preferably 3 to 10 seconds.

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 resin composition and the multilayer structure were evaluated by the following method.
(1) Gas barrier properties Under an atmosphere of 23 ° C. and 80% RH, the oxygen permeability and oxygen permeability coefficient of the film were measured according to ASTM D3985. The measurement used Modern Controls make and OX-TRAN 2/61. The lower the value, the better the gas barrier property.
Further, the oxygen transmission rate of the bottle was measured according to ASTM D3985 in an atmosphere of 23 ° C., 100% RH inside the bottle, and 50% outside the bottle. The measurement used Modern Controls make and OX-TRAN 2/61. The lower the value, the better the oxygen barrier property.
(2) Productivity and molding processability Using the resin composition as a barrier layer, a multilayer preform or multilayer film was molded, the number of bubbles generated in the barrier layer was evaluated, and the quality of the productivity and molding processability was judged. .
(3) Haze of the barrier layer obtained by cutting and taking out the multilayer preform formed by using the transparent resin composition as the barrier layer was measured.
According to JIS K-7105 and ASTM D1003, it measured with the haze value measuring apparatus (model: COH-300A) by Nippon Denshoku Industries Co., Ltd.

<Example 1>
Polymetaxylylene adipamide (MX Nylon S6007 manufactured by Mitsubishi Gas Chemical Co., Ltd.) 99.98% by weight as the polyamide (A), and ethylene bisstearylamide (Alfro H-50 manufactured by Nippon Oil & Fats Co., Ltd.) 0 as the component (B) 0 .02% by weight was dry blended in a tumbler for 5 minutes. A three-layer preform (27 g) comprising a polyester (F) layer / barrier layer / polyester (F) layer using the obtained resin composition as a barrier layer was produced by injection molding under the following conditions. The following conditions are such that the core-side injection cylinder temperature is higher than the normal set value, the core-side screw rotation speed is high, and the core-side screw back pressure is low, air is easily trapped, and many bubbles are generated. It is a condition.
The preform was cooled and then heated and biaxially stretched and blow molded to obtain a multilayer bottle. The resin constituting the polyester (F) layer is polyethylene terephthalate (Invista) having an intrinsic viscosity (a mixed solvent of phenol / tetrachloroethane = 6/4 (weight ratio), measuring temperature 30 ° C.) is 0.80. 1101) 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 was 10% by weight based on the total weight of the obtained multilayer bottle. The obtained bottle had an oxygen transmission rate of 0.009 cc / bottle · day · atm, indicating good barrier properties. The evaluation results are shown in Table 1.

(Three-layer preform shape)
Total length 88mm, outer diameter 20mm, wall thickness 4.2mm, weight 21g. For the production of the three-layer preform, an injection molding machine (manufactured by 4) made by Husky-Kortec was used. The screw used the general full flight type.
(Three-layer preform molding conditions)
Skin side injection cylinder temperature: 285 ° C
Core side injection cylinder temperature: 280 ° C
Resin channel temperature in mold: 280 ° C
Mold cooling water temperature: 15 ° C
Core side screw speed: 175rpm
Core side screw back pressure: 0 psi
Cooling time: listed in Table 1

(Multilayer bottle shape)
Total length 155mm, outer diameter 65mm, inner volume 350ml, 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 2>
Polymetaxylylene adipamide (MX Nylon S6007 manufactured by Mitsubishi Gas Chemical Co., Ltd.) 99.985% by weight as the polyamide (A), and polyoxyethylene sorbitan monolaurate (Nonion LT- manufactured by Nippon Oil & Fats Co., Ltd.) as the component (B) (221 kinematic viscosity 330 mm ^{2 / s)} 0.015% by weight was dry blended with a tumbler for 10 minutes. A multilayer bottle using the obtained resin composition as a barrier layer was obtained in the same manner as in Example 1. The obtained bottle had an oxygen transmission rate of 0.009 cc / bottle · day · atm, indicating good barrier properties. The evaluation results are shown in Table 1.

<Example 3>
Polymetaxylylene adipamide (MX Nylon S6007 manufactured by Mitsubishi Gas Chemical Co., Ltd.) 99.963% by weight as polyamide (A), 0.03% by weight of calcium stearate (manufactured by Kanto Chemical Co., Ltd.) as component (B), and 0.007% by weight of polyoxyethylene sorbitan monolaurate (Nonion LT-221, kinematic viscosity 330 mm ² / s manufactured by NOF Corporation) was dry blended for 15 minutes with a tumbler. A multilayer bottle using the obtained resin composition as a barrier layer was obtained in the same manner as in Example 1. The obtained bottle had an oxygen transmission rate of 0.009 cc / bottle · day · atm, indicating good barrier properties. The evaluation results are shown in Table 1.

<Example 4>
99.95% by weight of a polyamide (melting point 233 ° C., semi-crystallization time 59 s) composed of 95 mol% adipic acid and 5 mol% isophthalic acid as a diamine component as a diamine component as polyamide (A), As component (B), calcium stearate (manufactured by Kanto Chemical Co., Ltd.) 0.04% by weight, and polyoxyethylene sorbitan monolaurate (Nippon Oil & Fats Co., Ltd. Nonion LT-221 kinematic viscosity 330 mm ^{2 / s)} 0.01% by weight Was dry blended in a tumbler for 25 minutes. A multilayer bottle using the obtained resin composition as a barrier layer was obtained in the same manner as in Example 1. The obtained bottle had an oxygen permeability of 0.008 cc / bottle · day · atm, and exhibited a good barrier property. The evaluation results are shown in Table 1.

<Example 5>
99.98% by weight of a polyamide (melting point 226 ° C., semi-crystallization time 133 s) composed of 90% by mole of adipic acid and 10% by mole of isophthalic acid as a diamine component as a diamine component as polyamide (A), As component (B), calcium stearate (manufactured by Kanto Chemical Co., Inc.) 0.015% by weight, and polyoxyethylene sorbitan monolaurate (manufactured by Nippon Oil & Fats Co., Ltd. Nonion LT-221 kinematic viscosity 330 mm ^{2 / s)} 0.005% by weight Was dry blended with a tumbler for 20 minutes. A multilayer bottle using the obtained resin composition as a barrier layer was obtained in the same manner as in Example 1. The obtained bottle had an oxygen permeability of 0.008 cc / bottle · day · atm, and exhibited a good barrier property. The evaluation results are shown in Table 1.

<Comparative Example 1>
A multilayer bottle was obtained in the same manner as in Example 1 except that the barrier layer was changed to polymetaxylylene adipamide (MX Nylon S6007 manufactured by Mitsubishi Gas Chemical Company, Inc.). The evaluation results are shown in Table 1.

Abbreviations in Table 1 are as follows.
S6007: Polymetaxylylene adipamide (MX nylon S6007)
IPA-5: 5 mol% isophthalic acid modified polymetaxylylene adipamide
IPA-10: 10 mol% isophthalic acid modified polymetaxylylene adipamide
EBS: Ethylenebisstearylamide
Ca-ST: Calcium stearate
LT-221: Polyoxyethylene sorbitan monolaurate (nonion LT-221)

<Example 7>
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 The resin composition obtained in Example 4 was coextruded from the second extruder, and two types and three layers having a layer configuration of N6 layer (10 μm) / barrier layer (5 μm) / N6 layer (10 μm) A film is manufactured, and then an LLDPE film is dry laminated to obtain a three-layer four-layer multilayer film having a layer structure of LLDPE layer (20 μm) / N6 layer (10 μm) / barrier layer (5 μm) / N6 layer (10 μm). It was. As a barrier layer screw, a polyolefin full flight screw having a diameter (D) of 40 mm, L (screw length) / D = 24, a feed portion length of 8D, a compression portion length of 8D, a metalling portion of 8D, and a compression ratio of 2.46. used. The obtained film had an oxygen permeability of 0.4 cc / m ² · day · atm, and exhibited a good barrier property. In the multilayer film, the barrier layer was present uniformly, there was no air bubble, a stable quality film was obtained, and the productivity and moldability were good.

<Example 8>
As the barrier layer screw, a full flight screw for nylon having a diameter (D) of 40 mm, L (screw length) / D = 20, a feed portion length of 8D, a compression portion length of 4D, a metering portion of 8D, and a compression ratio of 3.96 is used. A multilayer film was produced in the same manner as in Example 7 except for the above. In the multilayer film, the barrier layer was present uniformly, there was no air bubble, a stable quality film was obtained, and the productivity and moldability were good.

<Example 9>
As the barrier layer screw, a double full flight screw having a diameter (D) of 40 mm, L (screw length) / D = 25, a feed portion length of 16D, a compression portion length of 5D, a metering portion of 4D, and a compression ratio of 2.67 is used. A multilayer film was produced in the same manner as in Example 7 except that. In the multilayer film, the barrier layer was present uniformly, there was no air bubble, a stable quality film was obtained, and the productivity and moldability were good.

As shown in the above examples, the resin composition of the present invention can be molded without changing the molding conditions, even if the molding conditions are such that air is easily involved and bubbles are easily generated. Since no air was involved even when using, productivity and moldability were improved. Further, whitening due to crystallization immediately after molding could be prevented, and transparency was improved even when the cooling time was short. Moreover, the gas barrier property was improved under high humidity.

Claims (14)

Polyamide (A) containing an aromatic ring in the skeleton, a fatty acid metal salt having 10 to 50 carbon atoms, a diamide compound obtained from a fatty acid having 8 to 30 carbon atoms and a diamine having 2 to 10 carbon atoms, and having 8 to 30 carbon atoms The resin composition containing the component (B) which consists of 1 or more types chosen from the diester compound obtained from a fatty acid and a C2-C10 diol, a nonionic surfactant, an anionic surfactant, and a cationic surfactant. The polyamide (A) is a polycondensation of a diamine component containing 70 mol% or more of metaxylylenediamine and a dicarboxylic acid component containing 70 mol% or more of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. The resin composition according to claim 1, wherein the resin composition is a polyamide obtained as described above. The polyamide (A) is a diamine component containing 70 mol% or more of metaxylylenediamine, 70 mol% or more of α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and 1 to 20 mol of isophthalic acid. 2. The resin composition according to claim 1, wherein the resin composition is a polyamide obtained by polycondensation with a dicarboxylic acid component containing 1%. The component (B) is a fatty acid metal salt having 10 to 50 carbon atoms, a diamide compound obtained from a fatty acid having 8 to 30 carbon atoms and a diamine having 2 to 10 carbon atoms, a fatty acid having 8 to 30 carbon atoms and 2 to 2 carbon atoms. The resin composition according to claim 1, wherein the resin composition is one or more selected from diester compounds obtained from 10 diols and nonionic surfactants. The resin composition according to claim 1, wherein the component (B) is at least one selected from fatty acid metal salts having 10 to 50 carbon atoms and nonionic surfactants. The resin composition according to claim 1, wherein the component (B) comprises a fatty acid metal salt having 10 to 50 carbon atoms and a nonionic surfactant. A multilayer structure comprising a barrier layer comprising the resin composition according to claim 1. The multilayer structure according to claim 7, comprising a layer mainly composed of polyester as a layer other than the barrier layer. The multilayer structure according to claim 7, further comprising a layer mainly composed of polyolefin as a layer other than the barrier layer. The multilayer structure according to claim 7, comprising a layer mainly composed of aliphatic polyamide as a layer other than the barrier layer. 9. The multilayer structure according to claim 8, wherein the polyester is a thermoplastic polyester resin obtained by polymerizing a dicarboxylic acid component in which 80 mol% or more is terephthalic acid and a diol component in which 80 mol% or more is ethylene glycol. object. The multilayer structure according to claim 11, which is a multilayer bottle having a three-layer structure of polyester layer / barrier layer / polyester layer. The multilayer structure according to claim 11, which is a multilayer bottle having a five-layer structure of polyester layer / barrier layer / polyester layer / barrier layer / polyester layer. The multilayer structure according to claim 12 or 13, wherein the weight of the barrier layer is 1 to 20% by weight with respect to the total weight of the multilayer structure.