JP2015071710A - Resin composition, multilayer structure and thermoforming container formed of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition capable of suppressing defects due to thermoforming, excellent in appearance and having sufficient intensity when forming a thermoforming container formed of a multilayer structure having at least one layer of a resin composition layer including EVOH, polyolefin, and saturated ketone, and to provide a multilayer structure and a thermoforming container excellent in appearance and impact resistance even when a sheet end part including the resin composition and a scrap are collected repeatedly.SOLUTION: Provided is the resin composition comprising (A) ethylene-vinyl alcohol copolymer, (B) polyolefin, and (C) saturated ketone, in which (C) the saturated ketone is 0.01 ppm or more and 100 ppm or less.

Description

  The present invention relates to a resin composition containing an ethylene-vinyl alcohol copolymer, a polyolefin and a saturated ketone, a multilayer structure having at least one layer composed of this resin composition, a thermoformed container composed of a multilayer structure, and It relates to a manufacturing method.

  An ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as “EVOH”) is widely used as a material that can be melt-molded and has excellent gas barrier properties. For example, EVOH is used as a material for films and sheets formed by melt molding. The EVOH layer made of this sheet or the like is used as a packaging material by being laminated with a thermoplastic resin layer mainly composed of a polyolefin resin or the like. A packaging material including such an EVOH layer is used as a packaging container by thermoforming. Such a packaging container is excellent in oxygen barrier properties by including an EVOH layer, and therefore is widely used in various fields such as foods, cosmetics, medicinal chemicals, and toiletries where oxygen barrier properties are required. At this time, there are cases where an end portion or defective products generated when obtaining the above various molded products are collected, melt-molded, and reused as at least one layer of a multilayer structure including a polyolefin layer and an EVOH layer. Such a recovery technique is useful in terms of waste reduction and economy, and is widely adopted.

  However, when the recovered material of the multilayer structure including the polyolefin layer and the EVOH layer is reused, gelation may occur due to thermal deterioration during melt molding, or the deteriorated material may adhere to the extruder, causing a long period of time. It was difficult to perform continuous melt molding. In addition, when such a deteriorated product adheres to the inside of the extruder, there is a problem that unevenness occurs in the obtained molded product. Furthermore, as the reuse of the recovered material of the multilayer structure was repeated, these problems became remarkable.

  As a measure for solving such a problem, for example, Patent Document 1 discloses a polyolefin; an ethylene-vinyl acetate copolymer saponification having an ethylene content of 20 to 65 mol% and a saponification degree of a vinyl acetate component of 96 mol% or more. At least one compound selected from a higher fatty acid metal salt having 8 to 22 carbon atoms, a metal salt of ethylenediaminetetraacetic acid and hydrotalcite; and an ethylene content of 68 to 98 mol% and a saponification degree of the vinyl acetate component of 20 % Or more of a resin composition comprising ethylene-vinyl acetate copolymer saponified product. Furthermore, it is described that the higher fatty acid metal salt having 8 to 22 carbon atoms is preferably a metal salt of higher fatty acid such as lauric acid, stearic acid and myristic acid, and calcium, magnesium and zinc. This resin composition has excellent compatibility, and the surface of a molded product obtained using this resin composition has no wave pattern and is said to have a beautiful appearance. However, the resin composition containing calcium stearate described in the examples of Patent Document 1 may cause deposits on the screw and may cause unevenness in the resulting molded product.

  Patent Document 2 contains ethylene-vinyl acetate containing 10 to 500 ppm of at least one selected from magnesium, calcium and zinc, having an ethylene content of 10 to 60 mol% and a saponification degree of the vinyl acetate component of 95 mol% or more. A method for producing a fuel container is described, wherein a saponified product of a copolymer is used as an intermediate layer, and a pulverized product of a laminate in which a thermoplastic resin is laminated at least on both outermost layers is used as a regrind layer (recovery layer). Yes. Here, a saponified ethylene-vinyl acetate copolymer in which a fatty acid metal salt is blended in the intermediate layer of the laminate used for the regrind layer is used. As the fatty acid metal salt, at least one selected from a magnesium salt, a calcium salt, and a zinc salt is used. As the fatty acid, a lower fatty acid and / or a higher fatty acid is used. According to this manufacturing method, it is said that a fuel container excellent in melt moldability, mechanical properties and the like can be obtained. However, with the compounding amount of zinc stearate described in the example of Patent Document 2, there is a problem that the deteriorated product adheres to the screw during melt molding of the laminate, and the resulting molded product has irregularities.

  Furthermore, the technique of the above-mentioned document is still insufficient from the viewpoint of suppressing the molding failure when the collected material is reused a plurality of times and the reduction in impact resistance due to the molding failure.

  As a method for producing EVOH, a method is known in which crotonaldehyde is coexisted in addition to ethylene and vinyl acetate in the EVOH polymerization step (see Patent Document 3). According to this production method, scale adhesion inside the polymerization can can be suppressed by allowing crotonaldehyde to coexist during the polymerization. As a result, the EVOH film obtained by this manufacturing method is said to be able to reduce the generation of fish eyes caused by scale contamination.

  However, the crotonaldehyde added during the polymerization is partially consumed in the polymerization process and the saponification process. Crotonaldehyde has a high solubility in water of 18.1 g / 100 g (20 ° C.) (The MERCK INDEX 14th 2006). On the other hand, the EVOH production method usually includes a step of washing with water sodium acetate produced by neutralization after saponification. Therefore, crotonaldehyde added at the time of polymerization is almost completely removed in the water washing step at the time of EVOH production, and hardly remains in products such as EVOH films. Therefore, in the above production method, the effects of adding saturated ketones such as improvement in thermal stability and long-term operation characteristics (long run properties) in thermoforming are unknown.

  As described above, it has been difficult for the prior art to improve the appearance defect and suppress the reduction in impact resistance when the collection and reuse of the resin composition are repeated a plurality of times.

Japanese Patent Laid-Open No. 3-72542 JP 2001-348017 A JP 2007-31725 A

  An object of the present invention is to provide a resin composition and a thermoformed container that are suppressed in occurrence of defects in thermoforming, have an excellent appearance, and have sufficient strength. Furthermore, an object of the present invention is to provide a production method that can provide a thermoformed container having such characteristics and is excellent in long-run property. In addition, when the recovered material obtained by repeatedly recovering sheet edges and scraps containing the resin composition is a layer in the multilayer structure, thermal degradation or aggregation of EVOH in the recovered material does not occur. There is no deterioration in compatibility with the thermoplastic resin, and the reduction in impact resistance of the resulting multilayer container is suppressed.

  The invention made in order to solve the above problems is an ethylene-vinyl alcohol copolymer (A) (hereinafter also referred to as “EVOH (A)”), a polyolefin (B) (hereinafter also referred to as “PO (B)”). ) And a saturated ketone (C), and the content of the saturated ketone (C) is 0.01 ppm or more and 100 ppm or less.

  Since the resin composition of the present invention contains the components (A) to (C), it is possible to effectively suppress the generation of kogation in the apparatus even when the thermoforming apparatus is operated for a long time. The operation time can be extended. In addition, a multilayer container excellent in impact resistance is provided even when sheet ends and scraps containing this resin composition are repeatedly collected. Although it is not necessarily clear why the resin composition has the above effect, for example, by containing EVOH (A), PO (B), and saturated ketone (C) at the specific content, respectively. The effect of containing these components is exhibited synergistically, and as a result, the continuous operation time can be extended.

  The saturated ketone (C) preferably has 3 to 8 carbon atoms. The saturated ketone (C) is preferably at least one selected from the group consisting of acetone, methyl ethyl ketone and 2-hexanone. The thermoformed container has excellent appearance and sufficient strength because the EVOH layer (A) contains a specific substance as the saturated ketone (C). Furthermore, if it is less than the minimum of saturated ketone (C), the impact resistance fall of the multilayer container obtained at the time of long-term continuous operation cannot be suppressed. Moreover, when the content of the saturated ketone (C) exceeds the upper limit, the EVOH aggregates by reacting with the condensation of saturated ketones (C) or the condensate of EVOH and saturated ketone (C) and increasing the viscosity, As a result, the impact resistance is reduced.

  The resin composition may further contain an acid-modified polyolefin. By adding acid-modified polyolefin to the resin composition, aggregation of EVOH (A) in the resin composition in a micro region is suppressed.

  The resin composition may further contain a fatty acid metal salt. The inclusion of a fatty acid metal salt is preferable because a multilayer structure and a thermoformed container excellent in appearance and mechanical strength (impact resistance) can be produced.

  The multilayer structure has a layer made of the resin composition and a layer made of other components. A multilayer structure having a layer made of the resin composition and a layer made of another component is preferable because it has good appearance and impact resistance.

  In the multilayer structure, the layer composed of other components is preferably a layer composed of the ethylene-vinyl alcohol copolymer (A) and a layer composed of the polyolefin (B). By providing a layer formed from the resin composition having the above-described characteristics and a layer composed of other components, the appearance, impact resistance, processing characteristics, and economy are excellent.

  The thermoformed container of the present invention is preferably composed of the multilayer structure. The thermoformed container is preferably a blow molded article. The thermoforming container is preferably manufactured by a step of thermoforming the multilayer structure, and the thermoforming is preferably a blow molding method. By forming the multilayer structure by thermoforming, particularly by blow molding, it is excellent in appearance and impact resistance.

  As described above, the resin composition of the present invention contains EVOH (A), PO (B) and saturated ketone (C), so that the occurrence of defects in thermoforming is suppressed and the appearance is excellent. And a thermoformed container having sufficient strength. Furthermore, this invention provides the manufacturing method which can provide the thermoforming container which has such a characteristic, and is excellent in long run property. Even when sheet edges and scraps containing this resin composition are repeatedly collected, the appearance and mechanical properties are reduced by suppressing the thermal degradation of EVOH in the collected material and maintaining and improving the compatibility with PO. A multilayer structure or a thermoformed container excellent in strength (impact resistance) can be produced. The resin composition and multilayer structure are suitable as molding materials for various thermoformed containers and packaging materials such as bottles, cups, trays, and fuel containers because they are excellent in appearance, impact resistance, and processing characteristics.

  Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto. Moreover, as long as there is no description in particular, the material illustrated may be used individually by 1 type, and may use 2 or more types together.

[Resin composition]
The resin composition of the present invention is a resin composition containing EVOH (A), PO (B), and a saturated ketone (C), wherein the content of the saturated ketone (C) with respect to the resin composition Is a resin composition having 0.01 ppm or more and 100 ppm or less. Here, “ppm” is a mass ratio of the corresponding component in the entire resin composition, and 1 ppm is 0.0001 mass%. The resin composition includes, as an optional component, a boron compound, a phosphorus compound, an aliphatic carboxylic acid, an aliphatic carboxylate, an antioxidant, an ultraviolet absorber, a plasticizer, and an antistatic material as long as the effects of the present invention are not impaired. An agent, a lubricant, a colorant, a filler, a heat stabilizer, a hydrotalcite compound and the like may be contained. Hereinafter, each component will be described.

<EVOH (A)>
EVOH (A) is an ethylene-vinyl alcohol copolymer obtained by saponifying a copolymer of ethylene and vinyl ester.

  Examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl pivalate and the like, and vinyl acetate is preferable. These vinyl esters may be used alone or in combination of two or more.

  EVOH (A) may contain other structural units derived from monomers other than ethylene units and vinyl ester units. Examples of such monomers include vinyl silane compounds and other polymerizable compounds. As content of said other structural unit, 0.0002 mol% or more and 0.2 mol% or less are preferable with respect to all the structural units of EVOH (A).

  Examples of the vinylsilane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, and the like. Among these, vinyltrimethoxysilane and vinyltriethoxysilane are preferable.

  Examples of the other polymerizable compounds include unsaturated hydrocarbons such as propylene and butylene; unsaturated carboxylic acids such as (meth) acrylic acid; and vinylpyrrolidones such as N-vinylpyrrolidone.

  The ethylene unit content of EVOH (A) is usually from 20 mol% to 60 mol%, preferably from 24 mol% to 55 mol%, more preferably from 27 mol% to 45 mol%, more preferably 27 mol%. The content is more preferably 42 mol% or less and particularly preferably 27 mol% or more and 38 mol% or less. If the ethylene content is less than 20 mol%, the thermal stability during melt extrusion tends to decrease and gelation tends to occur, and defects such as streaks and fish eyes may easily occur. In particular, if the operation is performed for a long time at a high temperature or at a higher speed than the general melt extrusion conditions, the possibility of gelation increases. On the other hand, when ethylene content exceeds 60 mol%, gas barrier properties etc. will fall and there exists a possibility that the advantageous characteristic which EVOH (A) has cannot fully be exhibited.

  The degree of saponification of the structural unit derived from the vinyl ester of EVOH (A) is 80% or more, preferably 85% or more, more preferably 90% or more, more preferably 95 mol%, further preferably 98% or more. 99% or more is particularly preferable. If the degree of saponification is less than 85%, the thermal stability may be insufficient.

<Polyolefin (PO) (B)>
Examples of the polyolefin (B) used in the present invention include polyethylene (low density, linear low density, medium density, high density, etc.); ethylene and 1-butene, 1-hexene, 4-methyl-1-pentene, etc. Copolymer of ethylene-based copolymer obtained by copolymerizing α-olefins or acrylic acid ester of polypropylene; polypropylene; propylene and α-olefins such as ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene Propylene-based copolymer; poly (1-butene), poly (4-methyl-1-pentene), the above-mentioned polyethylene, ethylene-based copolymer, polypropylene, propylene-based copolymer, poly (1-butene) or poly Modified polyolefin obtained by allowing maleic anhydride to act on (4-methyl-1-pentene); ionomer resin and the like. Among these, polypropylene resins such as polypropylene and propylene copolymers, or polyethylene resins such as polyethylene and ethylene copolymers are preferable. Polyolefin (B) may be used individually by 1 type, and may mix and use 2 or more types. In particular, when a multilayer structure having a layer made of the resin composition of the present invention is used as a food packaging material, a polyethylene resin is preferably used from the viewpoint of excellent secondary processability.

  The ratio of EVOH (A) and PO (B) in the resin composition in the present invention is such that EVOH (A) is 0.1 to 99.9% by mass and PO (B) is 0.1 to 99.9% by mass. The range is preferable, and the EVOH (A) content is more preferably 30% by mass or less, and further preferably 10% by mass or less, from the viewpoint of impact strength in the multilayer container.

<Saturated ketone (C)>
The resin composition contains a saturated ketone (C) as an essential component. The resin composition containing the saturated ketone (C) can suppress the occurrence of defects such as gelled blisters and streaks due to melt molding, and is excellent in appearance.

  Here, the saturated ketone (C) refers to a ketone that does not contain an unsaturated bond in a portion other than the carbonyl group in the molecule. As long as the saturated ketone (C) does not contain an unsaturated bond in a portion other than the carbonyl group, it may be a linear ketone or a branched ketone, and a ketone having a ring structure in the molecule. It may be. The number of carbonyl groups in the molecule of the saturated ketone (C) may be 1 or 2 or more.

  Examples of the saturated ketone (C) include saturated aliphatic ketones and saturated cyclic ketones.

  Examples of saturated aliphatic ketones include acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 3-methyl-2-butanone, 2-hexanone, 3-hexanone, 4-methyl-2-pentanone, 2-methyl-3- Pentanone, 3,3-dimethyl-2-butanone, 2-heptanone, 3-heptanone, 4-heptanone, 4-methyl-2-hexanone, 5-methyl-2-hexanone, 2,4-dimethyl-3-pentanone, 2-octanone, 3-methyl-2-heptanone, 5-methyl-3-heptanone, 3-octanone, 6-methyl-2-heptanone, 2-nonanone, 5-nonanone, 2,6-dimethyl-4-heptanone, 2,2,4,4-tetramethyl-3-pentanone, 6-undecanone, 2-undecanone, 7-tridecanone, methylcyclo Pentyl ketone, and the like methylcyclohexyl ketone.

  Examples of saturated cyclic ketones include cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, cyclononanone, cyclodecanone, cycloundecanone, and cyclododecanone.

  As carbon number of saturated ketone (C), from a viewpoint of the water solubility improvement of saturated ketone (C), 3-50 are preferable, 3-15 are more preferable, and 3-8 are more preferable. As the saturated ketone (C), among the exemplified examples, saturated aliphatic ketones are preferable from the viewpoint of suppressing generation of defects and coloring due to melt molding and improving long run properties, and acetone, methyl ethyl ketone, and 2-hexanone are more preferable. Acetone is more preferred.

  In the saturated ketone (C), part or all of the hydrogen atoms may be substituted with a substituent as long as the effects of the present invention are not impaired. Examples of the substituent include a halogen atom, a hydroxy group, an amino group, an amide group, and a cyano group.

  The lower limit of the saturated ketone (C) content in the resin composition is 0.01 ppm, preferably 0.05 ppm, more preferably 0.1 ppm, further preferably 0.15 ppm, and particularly preferably 0.2 ppm. . The upper limit of the content of the saturated ketone (C) is 100 ppm, preferably 95 ppm, more preferably 50 ppm, still more preferably 30 ppm, and particularly preferably 20 ppm. When the content of the saturated ketone (C) is less than the above lower limit, it is insufficient to suppress an increase in the occurrence of gelled puncture over time in melt molding. On the other hand, if the content of the saturated ketone (C) exceeds the above upper limit, condensation of saturated ketones or cross-linking of the condensate of EVOH and saturated ketone occurs at the time of melt molding, which may induce the generation of fish eyes and stripes. Furthermore, there is a possibility that the multilayer structure made of the resin composition is likely to be colored.

  In particular, the resin composition exhibits an excellent effect of suppressing thickening due to thermal degradation of EVOH (A) even when sheet ends, scraps, and the like containing the resin composition are repeatedly collected. Specifically, by adding saturated ketone (C), the resin composition with polyolefin (B) improves the dispersibility of EVOH during repeated recovery, and the mechanical strength of the resulting molded product, That is, the effect of suppressing the decrease in impact resistance can be obtained.

<Acid-modified polyolefin>
By adding the acid-modified polyolefin to the resin composition, aggregation of EVOH (A) in the resin composition in a micro region is suppressed.

  Examples of the acid-modified polyolefin include an olefin polymer in which an unsaturated carboxylic acid or a derivative thereof is introduced through a chemical bond. Specific examples include maleic anhydride graft-modified polyethylene and maleic anhydride graft-modified polypropylene. Maleic anhydride graft-modified polyolefin; maleic anhydride graft-modified ethylene-propylene (block or random) copolymer, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer And a maleic anhydride graft-modified product of a copolymer of an olefin and a vinyl monomer. These olefin polymers can be used alone or in combination of two or more.

  The acid-modified polyolefin is preferably 1% by mass to 20% by mass, more preferably 3% by mass to 15% by mass, and still more preferably 5% by mass to 10% by mass with respect to the resin composition.

<Fatty acid metal salt>
By adding the fatty acid metal salt to the resin composition, it is possible to produce a multilayer structure or a thermoformed container excellent in appearance and mechanical strength (impact resistance).

  Examples of the fatty acid metal salt include a metal salt of a higher fatty acid having 10 to 26 carbon atoms such as lauric acid, stearic acid, myristic acid, behenic acid, and montanic acid, particularly Group 1, Group 2 or Group 3 of the periodic table. Metal salts such as sodium salt, potassium salt, calcium salt, and magnesium salt. Moreover, the zinc salt of the above-mentioned fatty acid can also be used. Among these, metal salts of Group 2 of the periodic table such as calcium salts and magnesium salts are preferable.

  The fatty acid metal salt is preferably from 50 ppm to 10,000 ppm, more preferably from 100 ppm to 8,000 ppm, even more preferably from 150 ppm to 5,000 ppm, particularly preferably from 200 ppm to 4,000 ppm, based on the resin composition.

<Optional component>
The resin composition includes a boron compound, a phosphorus compound, an aliphatic carboxylic acid, an aliphatic carboxylate, a conjugated polyolefin, an antioxidant, an ultraviolet absorber, a plasticizer, an antistatic agent, a lubricant, a colorant, a filler, A talcite compound or the like may be contained. The resin composition may contain two or more of these components. The total content of these optional components is preferably 1% by mass or less in the resin composition.

(Boron compound)
The boron compound suppresses gelation during melt molding and suppresses torque fluctuations (viscosity change during heating) of an extruder or the like.

Examples of the boron compound include boric acids such as orthoboric acid, metaboric acid, and tetraboric acid; boric acid esters such as triethyl borate and trimethyl borate;
Borate salts such as alkali metal salts or alkaline earth metal salts of borates, borax;
Examples thereof include borohydrides. Among these, boric acids are preferable, and orthoboric acid (hereinafter also referred to as “boric acid”) is more preferable.

  As a minimum of content of a boron compound in a resin composition, 100 ppm is preferred and 150 ppm is more preferred. The upper limit of the boron compound content is preferably 5,000 ppm, more preferably 4,000 ppm, and even more preferably 3,000 ppm. If the boron compound content is less than the above lower limit, torque fluctuations in an extruder or the like may not be sufficiently suppressed. On the other hand, if the content of the boron compound exceeds the above upper limit, gelation tends to occur during melt molding, and the appearance of the multilayer structure or thermoformed container may be deteriorated.

(Phosphorus compound)
The phosphorus compound suppresses generation and coloring of defects such as streaks and fish eyes and improves long run properties.

  Examples of the phosphorus compound include various phosphoric acids such as phosphoric acid and phosphorous acid, and phosphates. As said phosphate, any form of a 1st phosphate, a 2nd phosphate, and a 3rd phosphate may be sufficient. Further, the cationic species is not particularly limited. The phosphate is preferably an alkali metal salt or alkaline earth metal salt, more preferably sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, or dipotassium hydrogen phosphate, sodium dihydrogen phosphate. More preferred is dipotassium hydrogen phosphate.

(Aliphatic carboxylic acid)
In addition to the fatty acid metal salt described above, an aliphatic carboxylic acid may be added. As the aliphatic carboxylic acid, a saturated aliphatic carboxylic acid having 1 to 26 carbon atoms is preferable, a saturated aliphatic carboxylic acid having 1 to 12 carbon atoms is more preferable, and a saturated aliphatic carboxylic acid having 1 to 9 carbon atoms is more preferable. Acetic acid is particularly preferred.

  The content of the aliphatic carboxylic acid is preferably 50 ppm to 10,000 ppm, more preferably 100 ppm to 8,000 ppm, further preferably 150 ppm to 5,000 ppm, and particularly preferably 200 ppm to 4,000 ppm. If the content of the aliphatic carboxylic acid is less than 50 ppm, a sufficient anti-coloring effect cannot be obtained, and thus yellowing may be observed in a molded product formed from the resin composition. When the content of the aliphatic carboxylic acid exceeds 10,000 ppm, the resin composition tends to gel during melt molding, particularly during long melt molding, and the appearance of the molded product may be poor.

(Aliphatic carboxylate)
In addition to the fatty acid metal salt described above, an aliphatic carboxylate may be added. As the aliphatic carboxylate, a saturated aliphatic carboxylate having 1 to 9 carbon atoms is preferable, and acetate is more preferable. Furthermore, both the aliphatic carboxylic acid and the aliphatic carboxylate may be used, both acetic acid and acetate are more preferably used, and acetic acid and sodium acetate are more preferably used.

  The content of the aliphatic carboxylate is preferably from 50 ppm to 10,000 ppm, more preferably from 100 ppm to 8,000 ppm, further preferably from 150 ppm to 5,000 ppm, particularly preferably from 200 ppm to 4,000 ppm. If the content of the aliphatic carboxylate is less than 50 ppm, a sufficient anti-coloring effect cannot be obtained, and thus yellowing may be observed in a molded product formed from the resin composition. When the content of the aliphatic carboxylate salt exceeds 10,000 ppm, the resin composition is likely to gel during melt molding, particularly during long melt molding, and the appearance of the molded product may be poor. .

(Conjugated polyene compound)
The conjugated polyene compound suppresses oxidative degradation during melt molding. Here, the conjugated polyene compound is a so-called conjugated double compound having a structure in which carbon-carbon double bonds and carbon-carbon single bonds are alternately connected and having two or more carbon-carbon double bonds. A compound having a bond. This conjugated polyene compound may be a conjugated diene having two conjugated double bonds, a conjugated triene having three, or a conjugated polyene having more than that number. In addition, a plurality of conjugated double bonds may be present in one molecule without being conjugated with each other. For example, a compound having three conjugated triene structures in the same molecule such as tung oil is also included in the conjugated polyene compound.

  The number of conjugated double bonds in the conjugated polyene compound is preferably 7 or less. When the resin composition contains a conjugated polyene compound having 8 or more conjugated double bonds, there is a high possibility that the multilayer structure and thus the thermoformed container will be colored.

  Conjugated polyene compounds include, in addition to conjugated double bonds, carboxyl groups and salts thereof, hydroxyl groups, ester groups, carbonyl groups, ether groups, amino groups, imino groups, amide groups, cyano groups, diazo groups, nitro groups, sulfone groups. And salts thereof, sulfonyl groups, sulfoxide groups, sulfide groups, thiol groups, phosphate groups and salts thereof, phenyl groups, halogen atoms, non-conjugated double bonds, triple bonds and other functional groups. .

Examples of the conjugated polyene compound include isoprene, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-t-butyl-1,3-butadiene, and 1,3-pentadiene. 2,3-dimethyl-1,3-pentadiene, 2,4-dimethyl-1,3-pentadiene, 3,4-dimethyl-1,3-pentadiene, 3-ethyl-1,3-pentadiene, 2-methyl -1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 1,3-hexadiene, 2,4-hexadiene, 2,5-dimethyl-2,4-hexadiene 1,3-octadiene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 1-phenyl-1,3-butadiene, 1,4-diphenyl-1,3-butadiene Ene, 1-methoxy-1,3-butadiene, 2-methoxy-1,3-butadiene, 1-ethoxy-1,3-butadiene, 2-ethoxy-1,3-butadiene, 2-nitro-1,3-butadiene Butadiene, chloroprene, 1-chloro-1,3-butadiene, 1-bromo-1,3-butadiene, 2-bromo-1,3-butadiene, oxime, ferrandrene, myrcene, farnesene, sorbic acid, sorbic acid ester, Conjugated diene compounds such as sorbate;
Conjugated triene compounds such as 1,3,5-hexatriene, 2,4,6-octatriene-1-carboxylic acid, eleostearic acid, tung oil, cholecalciferol, fulvene, and tropone;
Examples thereof include conjugated polyene compounds such as cyclooctatetraene, 2,4,6,8-decatetraene-1-carboxylic acid, retinol, and retinoic acid. Conjugated polyene compound (III) may be used individually by 1 type, and may use 2 or more types together.

  As carbon number of a conjugated polyene compound, 4-30 are preferable and 4-10 are more preferable. Among the exemplified conjugated diene compounds, sorbic acid, sorbic acid ester, sorbate, myrcene, and a mixture of two or more thereof are preferable, and sorbic acid, sorbate, and a mixture thereof are more preferable. Sorbic acid, sorbate and a mixture thereof are highly effective in suppressing oxidative degradation at high temperatures, and are also widely used industrially as food additives, and thus are preferable from the viewpoint of hygiene and availability.

  The molecular weight of the conjugated polyene compound is usually 1,000 or less, preferably 500 or less, and more preferably 300 or less. When the molecular weight of the conjugated polyene compound exceeds 1,000, the dispersion state of the conjugated polyene compound in the resin composition may be deteriorated, and the appearance after melt molding may be deteriorated.

  As a minimum of content of a conjugated polyene compound in a resin composition, 0.01 ppm is preferred, 0.1 ppm is more preferred, 0.5 ppm is still more preferred, and 1 ppm is especially preferred. The upper limit of the content is preferably 1,000 ppm, more preferably 800 ppm or less, and even more preferably 500 ppm or less. If the content of the conjugated polyene compound is less than the above lower limit, the effect of suppressing oxidative deterioration during melt molding may not be sufficiently obtained. On the other hand, when the content of the conjugated polyene compound exceeds the upper limit, gelation of the resin composition may be promoted.

(Antioxidant)
Examples of the antioxidant include 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4′-thiobis (6-t-butylphenol), 2,2 Examples include '-methylene-bis (4-methyl-6-tert-butylphenol), octadecyl-3- (3', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate.

(UV absorber)
Examples of the ultraviolet absorber include ethylene-2-cyano-3,3′-diphenyl acrylate, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-). t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-oxybenzophenone and the like. It is done.

(Plasticizer)
Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, and phosphate ester.

(Antistatic agent)
Examples of the antistatic agent include pentaerythritol monostearate, sorbitan monopalmitate, sulfated polyolefins, polyethylene oxide, polyethylene glycol (trade name: carbowax), and the like.

(Lubricant)
Examples of the lubricant include ethylene bisstearamide, butyl stearate and the like.

(Coloring agent)
The colorant (also referred to as “pigment”) is not particularly limited, and various organic pigments and inorganic pigments are employed depending on the color of the target multilayer structure. Examples of organic pigments include azo pigments, quinacridone pigments, and phthalocyanine pigments, and one or more of these are used. Examples of inorganic pigments include titanium oxide, zinc oxide, zinc sulfide, carbon black, lead pigments, cadmium pigments, cobalt pigments, iron pigments, chromium pigments, ultramarine and bitumen, and one of these. Or 2 or more types are used.

(filler)
Examples of the filler include glass fiber, ballastite, calcium silicate, talc, montmorillonite and the like.

(Hydrotalcite)
Hydrotalcite suppresses deterioration of EVOH due to halogen ions present in the resin composition during melt molding. The _{hydrotalcite,} at least _{M x Al y (OH) 2x} + 3y-2z (R) z · aH 2 O (M is Mg, Ca, Sr, Ba, Zn, Cd, Pb, selected from the group consisting of Sn 1 R represents CO ₃ or HPO ₄ , x, y, z are positive numbers, a is 0 or positive numbers, and 2x + 3y−2z> 0). Hydrotalcite can be mentioned as a suitable thing.
In these hydrotalcites, M is more preferably Mg, Ca or Zn, and a combination of two or more of these is more preferable. Among these hydrotalcites, the following are particularly preferable.
Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O
_{Mg 8 Al 2 (OH) 20} CO 3 · 5H 2 O
Mg ₅ Al ₂ (OH) ₁₄ CO ₃ .4H ₂ O
_{Mg 10 Al 2 (OH) 22} (CO 3) 2 · 4H 2 O
_{Mg 6 Al 2 (OH) 16} HPO 4 · 4H 2 O
Ca ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O
Zn ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O
Mg ₃ ZnAl ₂ (OH) ₁₂ CO ₃ · 2.7H ₂ O
Mg ₆ Zn ₂ Al ₂ (OH) ₂₀ CO ₃ .1.6H ₂ O
Mg ₅ Zn _1.7 Al _3.3 (OH) ₂₀ (CO ₃ ) _1.65 · 4.5H ₂ O

  In addition, as a measure for preventing the occurrence of gel in the resin composition, 0.01% by mass to 1% by mass of one or more thermal stabilizers such as the hydrotalcite compound, hindered phenol compound, hindered amine compound, and the like. % Can be added.

[Method for Producing Resin Composition]
The method for producing the resin composition is not particularly limited as long as EVOH (A), PO (B), and saturated ketone (C) can be blended uniformly.

Examples of a method for uniformly blending the saturated ketone (C) in the resin composition with the above-mentioned specific content with respect to the resin component include, for example, (1) a step of copolymerizing ethylene and vinyl ester, and (2) It can be obtained by a production method including a step of saponifying the copolymer obtained in the step (1).

The method for containing a specific amount of saturated ketone (C) in the resin composition is not particularly limited. For example, a method of adding a specific amount of saturated ketone (C) in the above step (1),
A method of adding a specific amount of saturated ketone (C) in the step (2),
A method of adding a specific amount of saturated ketone (C) to EVOH (A) obtained by the above step (2),
A method of adding a specific amount of saturated ketone (C) when blending EVOH (A) obtained by the above step (2) and polyolefin (B),
The method etc. which use these methods together are mentioned.

  In addition, when employ | adopting the method of adding a specific amount of saturated ketone (C) in the said process (1), or the method of adding a specific amount of saturated ketone (C) in the said process (2), the said process ( It is necessary to add in the range which does not inhibit the polymerization reaction in 1) and the saponification reaction in the above step (2).

  Among these methods, from the viewpoint of easy adjustment of the content of the saturated ketone (C) in the resin composition, a specific amount of the saturated ketone (C) is added to the EVOH (A) obtained by the step (2). A method of adding a specific amount of saturated ketone (C) when blending the EVOH (A) obtained in step (2) and the polyolefin (B) is preferable, and is obtained by step (2). A method of adding a specific amount of saturated ketone (C) to EVOH (A) is more preferred.

  As a method of adding a specific amount of saturated ketone (C) to the EVOH (A), for example, a method in which a saturated ketone (C) is blended in advance with EVOH (A) and pellets are formed, ethylene-vinyl ester copolymer A method of impregnating a saturated ketone (C) into a strand precipitated in a step of depositing a paste after saponification of a coalescence, a method of impregnating a saturated ketone (C) after cutting the precipitated strand, a chip of a dry resin composition A method of adding saturated ketone (C) to a redissolved product, a method of melt kneading a blend of two components of EVOH (A) and saturated ketone (C), and melting EVOH (A) from the middle of the extruder A method of feeding a saturated ketone (C) into a product and containing it, a master batch prepared by granulating a part of EVOH (A) with a saturated ketone (C) at a high concentration and making E OH (A) and a method in which melt-kneading the dry blend can be mentioned.

  Among these, from the viewpoint that a small amount of saturated ketone (C) can be more uniformly dispersed in EVOH (A), the saturated ketone (C) is blended in advance with EVOH (A) and pellets are granulated. The method is preferred. Specifically, a saturated ketone (C) is added to a solution in which EVOH (A) is dissolved in a good solvent such as a water / methanol mixed solvent, and the mixed solution is extruded into a poor solvent from a nozzle or the like and precipitated. By pelletizing and / or drying, pellets in which saturated ketone (C) is uniformly mixed with EVOH (A) can be obtained.

  The resin composition is obtained by, for example, using a melt-kneading apparatus by a method of mixing a resin composition containing EVOH (A) and a saturated ketone (C) with an acid-modified polyolefin and / or a fatty acid metal salt. Each component can be obtained by melt-kneading. The method for blending is not particularly limited, and a ribbon blender, a high-speed mixer kneader, a mixing roll, an extruder, an intensive mixer, and the like can be used.

  Among these, as shown in Examples described later, generally, a single-screw or twin-screw extruder used when melt-blending a resin is most preferable. The order of addition is not particularly limited, and a method in which a resin component containing EVOH (A) and saturated ketone (C), PO (B) and a fatty acid metal salt are added simultaneously or in an appropriate order to an extruder and melt-kneaded. Is preferably employed. Moreover, you may add an arbitrary component at the time of melt-kneading.

[Multilayer structure]
If the multilayer structure of the present invention has at least one layer obtained by melt-molding the resin composition and a layer composed of other components, the layer structure, the total number of layers, and the layer thickness The ratio, the type of resin used in the other layers, the presence or absence of an adhesive resin, and the type thereof are not particularly limited.

  The layer composed of other components is preferably a layer composed of the ethylene-vinyl alcohol copolymer (A) and a layer composed of the polyolefin (B).

  Examples of the polyolefin (B) constituting the layer composed of other components include those exemplified for the polyolefin (B), polypropylene resins such as polypropylene and propylene copolymers, or polyethylene and ethylene copolymers. Polyethylene resins such as polymers are preferred

  The multilayer structure can be formed into an arbitrary molded product such as a film, a sheet, a tape, a cup, a tray, a tube, a bottle, and a pipe. Here, the film means a film having a thickness of usually less than 300 μm, and the sheet means a film having a thickness of usually 300 μm or more.

  The production method of the multilayer structure is not particularly limited, but for example, extrusion lamination method, dry lamination method, extrusion blow molding method, coextrusion lamination method, coextrusion molding method, coextrusion pipe molding method, coextrusion method Examples include blow molding, co-injection molding, and solution coating. From the viewpoint of versatility, coextrusion molding and co-injection molding are preferred. When co-extrusion molding or co-injection molding, it is more preferable to supply EVOH (A), polyolefin (B), other thermoplastic resin, adhesive resin and the like individually to the thermoforming apparatus.

  Among these, as a method for producing a multilayer structure, a coextrusion laminating method and a coextrusion molding method are more preferable, and a coextrusion molding method is more preferable. By laminating the resin composition layer and the layer composed of other components by the above method, it can be easily and reliably manufactured, and as a result, good appearance, impact resistance and processing characteristics are effective. Can be achieved.

<Adhesive resin>
Each layer of the multilayer structure may be laminated via an adhesive resin, and as the adhesive resin used as the adhesive resin layer, for example, the above acid-modified polyolefin is suitable.

[Production method of molded products]
Examples of a method for forming a molded product using the multilayer structure include a vacuum forming method, a pressure forming method, a vacuum / pressure forming method, and a blow forming method. These moldings are usually performed in a temperature range below the melting point of EVOH (A). Among these, the vacuum / pressure forming method is preferable. The vacuum / pressure forming method is a method in which a multilayer structure is heated and formed using both vacuum and compressed air. The molded product can be easily and reliably manufactured by using the above-described multilayer structure by a vacuum / pressure forming method, and as a result, is excellent in appearance and impact resistance.

  The melt molding temperature is preferably about 150 ° C. to 250 ° C., although it varies depending on the melting point of EVOH (A). When the molding temperature of EVOH (A) exceeds 250 ° C., the thermal degradation of EVOH is accelerated and induces poor appearance and reduced impact resistance due to thermal degradation during repeated collection.

  Extrusion molding of each layer is performed by operating an extruder equipped with a single screw at a predetermined temperature. The temperature of the extruder for forming the barrier layer is, for example, 170 ° C. to 210 ° C., the temperature of the extruder for forming the resin composition layer is, for example, 200 ° C. to 240 ° C., and a layer composed of other components is formed. The temperature of the extruder that performs this is, for example, 200 ° C. to 240 ° C., and the temperature of the extruder that forms the adhesive layer is, for example, 160 ° C. to 220 ° C.

  Further, the multilayer structure may be subjected to secondary processing in accordance with the target shape. Secondary processing includes methods such as stretching, thermoforming, and blow molding. Examples of the stretching method include a roll stretching method, a tenter stretching method, a tubular stretching method, and a stretching blow method. In the case of biaxial stretching, both a simultaneous biaxial stretching method and a sequential biaxial stretching method can be employed. Examples of thermoforming include a method of forming a film-like or sheet-like multilayer structure into a cup or tray by vacuum forming, pressure forming, vacuum air forming, or the like. Moreover, as blow molding, the method of shape | molding a parison-like multilayered structure into a bottle and a tube shape by blow is mentioned.

  The molded product obtained by the melt molding or the like may be further subjected to secondary processing molding such as bending, vacuum molding, blow molding, press molding, or the like, if necessary, to obtain a target molded product.

  Since the said molded article is equipped with the layer formed from the resin composition which has the above-mentioned property, it can be used suitably for a thermoforming container, for example, a food packaging container, or a fuel container.

  The thermoformed container comprising the multilayer structure of the present invention can be molded according to the purpose, heat sealed as necessary to form a container, and the container can be filled with contents and used for transportation and storage. . As the contents, both foods and non-foods can be used, and any of dried products, those containing moisture, and those containing oils may be used. Moreover, the container which consists of a multilayer structure can also be used for a boil process and a retort process, In that case, the thing in which polypropylene is used for both outer layers, or a thing with a thick EVOH layer is used suitably.

(1) Measurement of water content of water-containing EVOH pellets Water content of water-containing EVOH pellets using a halogen moisture analyzer “HR73” manufactured by METTLER TOLEDO at a drying temperature of 180 ° C., a drying time of 20 minutes, and a sample amount of about 10 g. The rate was measured. The moisture content of the water-containing EVOH shown below is mass% based on the dry mass of EVOH.

(2) Ethylene content and saponification degree of EVOH (A) Using a nuclear magnetic resonance apparatus (superconducting nuclear magnetic resonance apparatus “Lambda 500”, manufactured by JEOL Ltd.), DMSO-d ₆ as a measurement solvent, ¹ H— Determined by NMR.

(3) Quantification of saturated ketone (C) 50 mg of 2,4-dinitrophenylhydrazine (DNPH) aqueous solution 200 mg, 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) 50 mL, acetic acid 11.5 mL and 8 mL of ion exchange water were added to prepare a DNPH solution. 1 g of the measurement pellet was added to 20 mL of this DNPH solution, and stirred at 35 ° C. for 1 hour to dissolve. Acetonitrile was added to this solution to precipitate the resin component and settled, and then the solution obtained by filtration was concentrated to obtain an extracted sample. Saturated ketone (C) was quantified by quantitatively analyzing the extracted sample by high performance liquid chromatography under the following conditions. In the determination, a calibration curve prepared using a standard obtained by reacting each saturated ketone (C) with a DNPH preparation solution was used.
(Measurement condition)
Column: TSKgel ODS-80Ts (manufactured by Tosoh)
Mobile phase: water / acetonitrile = 52: 48 (volume ratio)
Detector: PDA (360 nm)

(4) Quantification of Conjugated Polyene Compound The dried resin composition pellets were pulverized by freeze pulverization, and coarse particles were removed by a sieve having a nominal size of 0.150 mm (100 mesh) (conforming to JIS standard Z8801-1-3). 10 g of the pulverized product was filled in a Soxhlet extractor and extracted with 100 mL of chloroform for 48 hours. The amount of the conjugated polyene compound was quantitatively analyzed by high performance liquid chromatography to quantify the amount of the conjugated polyene compound. For quantification, a calibration curve prepared using a sample of each conjugated polyene compound was used.

(5) Odor during molding 20 g of the resin composition sample pellets were placed in a 100 mL glass sample tube, the mouth was covered with aluminum foil, and then heated in a hot air dryer at 220 ° C. for 30 minutes. After removing from the dryer and allowing to cool at room temperature for 30 minutes, the sample tube was shaken 2-3 times, and then the lid of the aluminum foil was removed to confirm the odor. The odor intensity of the sample pellets was evaluated according to the following criteria.

A: Do not feel odor B: Feel weak odor C: Clearly feel odor

(6) Determination of Aliphatic Carboxylic Acid (Fatty Acid Salt, Aliphatic Carboxylic Acid Ion of Aliphatic Carboxylate) A dried EVOH pellet, a resin composition or a resin composition subjected to a recovery operation was pulverized by freeze pulverization. The obtained pulverized product was divided by a sieve having a nominal size of 1 mm (standard fluid standard JIS Z8801-1-3 compliant). 10 g of the pulverized powder and 50 mL of ion-exchanged water that passed through the sieve were put into a 100 mL Erlenmeyer flask with a stopper, a cooling condenser was attached, and the mixture was stirred at 95 ° C. for 10 hours. 2 mL of the obtained solution was diluted with 8 mL of ion exchange water. By using the ion chromatography “ICS-1500” manufactured by Yokogawa Electric Corporation and quantifying the amount of the carboxylate ion according to the following measurement conditions, the diluted solution is used for aliphatic carboxylic acid (and aliphatic carboxylate ion). The amount of was calculated. A calibration curve prepared using each carboxylic acid was used for quantification.

(Measurement condition)
Column: IonPAC ICE-AS1 (9φ × 250 mm, manufactured by DIONEX, detector, electrical conductivity detector)
Eluent: 1.0 mmol / L Octanesulfonic acid aqueous solution Measurement temperature: 35 ° C. Eluent flow rate: 1 mL / min.
Analytical volume: 50 μL

(7) Quantitative determination of metal ions 0.5 g of dry EVOH pellets, resin composition or recovered resin composition was charged into a pressure-resistant container made of Actuac fluororesin, and 5 mL of nitric acid for precision analysis made by Wako Pure Chemical Industries, Ltd. was used. Added further. After standing for 30 minutes, the container is covered with a cap lip with a rupture disk, and processed at 150 ° C. for 10 minutes and then at 180 ° C. for 10 minutes with a microwave high-speed decomposition system “Speed Wave MWS-2” manufactured by Actac Corporation. Decomposed. When the decomposition of the resin was not completed, the processing conditions were adjusted as appropriate. The obtained decomposition product was diluted with 10 mL of ion exchange water, and all the liquids were transferred to a 50 mL volumetric flask and the volume was adjusted with ion exchange water to obtain a decomposition product solution.
The amount of metal ions, phosphate compounds, and boron compounds by quantitative analysis of the obtained decomposition product solution at each observation wavelength shown below using an ICP emission spectroscopic analyzer “Optima 4300 DV” manufactured by PerkinElmer Japan Was quantified. The amount of the phosphoric acid compound was calculated as phosphorus element equivalent mass by quantifying phosphorus element. The boron compound content was calculated as a boron element equivalent mass.
Na: 589.592 nm
K: 766.490 nm
Mg: 285.213 nm
Ca: 317.933 nm
P: 214.914 nm
B: 249.667 nm
Si: 251.611 nm
Al: 396.153 nm
Zr: 343.823 nm
Ce: 413.764 nm
W: 207.912 nm
Mo: 202.031 nm

[Synthesis of EVOH]
<Synthesis example>
Polymerization of the ethylene-vinyl acetate copolymer was carried out under the following conditions using a 250 L pressurized reactor.
83.0 kg of vinyl acetate,
26.6 kg of methanol,
Feed rate of 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (2.5 g / L methanol solution) 1119.5 mL / hr
Polymerization temperature 60 ° C
Polymerization tank ethylene pressure 3.6 MPa
Polymerization time 5.0 hours The polymerization rate of vinyl acetate in the obtained copolymer was about 40%. After adding sorbic acid to this copolymerization reaction solution, the sorbic acid is supplied to the extraction tower, and unreacted vinyl acetate is removed from the top of the tower by introducing methanol vapor from the bottom of the tower. % Methanol solution was obtained. The ethylene content of this ethylene-vinyl acetate copolymer was 32 mol%. This methanol solution of ethylene-vinyl acetate copolymer is charged into a saponification reactor, and caustic soda / methanol solution (80 g / L) is added so as to be 0.4 equivalent to the vinyl ester component in the copolymer. Then, methanol was added to adjust the copolymer concentration to 20%. This solution was heated to 60 ° C. and reacted for about 4 hours while blowing nitrogen gas into the reactor. This solution was extruded into water from a metal plate having a circular opening, precipitated, and cut to obtain pellets having a diameter of about 3 mm and a length of about 5 mm. The obtained pellet was drained with a centrifuge, and the operation of adding a large amount of water and draining was repeated.

[Preparation of EVOH resin composition]
20 kg of the lysed pellets were put into 180 kg of a mixed solvent of water / methanol = 40/60 (mass ratio) and stirred at 60 ° C. for 6 hours to completely dissolve the pellets. Saturated ketone (C) was added to the resulting solution, and the mixture was further stirred for 1 hour to completely dissolve the saturated ketone (C) to obtain an EVOH solution. This solution was continuously extruded from a nozzle having a diameter of 4 mm into a coagulation bath of water / methanol = 90/10 (mass ratio) adjusted to 0 ° C. to be solidified into a strand. This strand was introduced into a pelletizer to obtain a porous EVOH resin composition chip. The obtained porous EVOH resin composition chip was washed with an acetic acid aqueous solution and ion-exchanged water. The cleaning solution and the EVOH resin composition chip were separated and drained, and then put into a hot air dryer, dried at 80 ° C. for 4 hours, and further dried at 100 ° C. for 16 hours to obtain pellets. The content of each component in the obtained EVOH resin composition (A) was quantified by the above method.

[Preparation of resin composition]
<Example 1>
EVOH resin composition (A) 5.5 parts, polyolefin (B) 87 parts polyethylene (HZ8200B made by Prime Polymer Co., Ltd., hereinafter referred to as HDPE), acid-modified polyolefin (D) (Mitsui Chemicals Co., Ltd. Admer GT-) 6A, hereinafter referred to as AD) 7.5 parts and 0.15 part of a fatty acid metal salt were mixed, and a saturated ketone (C) was added as necessary to obtain a mixture.
Under the pelletizing conditions shown below, the above mixture was melt-kneaded to obtain 20 kg of resin compositions having the compositions shown in Table 1 (hereinafter referred to as resin composition (E)). The obtained resin composition was melted and kneaded again, and the operation of taking it out from the kneader was repeated, so that 20 kg of the resin composition (E) each having 5 times and 10 times of melt kneading (hereinafter referred to as the number of times of recovery) was obtained. It was. The melt kneading temperature of the resin composition (E) was carried out at 250 ° C., which is higher than usual, while the normal EVOH kneading temperature condition is about 150 ° C. to 250 ° C. The content of saturated ketone (C) was quantified by the above method. Moreover, fatty acid metal salt was made into content with the mass at the time of adjusting a mixture.
(Pelletizing conditions)
Extruder: Toyo Seiki Seisakusho Co., Ltd. twin screw extruder "Lab Plast Mill"
Screw diameter: 25mmφ
Screw rotation speed: 100rpm
Feeder rotation speed: 100 rpm
Cylinder, die temperature setting: C1 / C2 / C3 / C4 / C5 / D
= 180 ° C / 230 ° C / 250 ° C / 250 ° C / 250 ° C / 250 ° C

<Examples 2 to 5, Comparative Examples 1 and 2>
A mixture shown in Table 1 was prepared, and a resin composition was prepared in the same manner as in Example 1.

[Production of multilayer structure]
Using a co-extrusion molding apparatus, the EVOH resin composition (A), polyolefin (B) (polyethylene), carboxylic acid-modified polyolefin (D) (“QF-500” manufactured by Mitsui Chemicals Admer), and resin composition (E ) In a separate extruder, and a multilayer sheet (layer structure: polyolefin (B) layer 300 μm / carboxylic acid modified polyolefin (D) 50 μm / EVOH (A) layer 50 μm / Carboxylic acid-modified polyolefin (D) 50 μm / resin composition (E) layer 400 μm / polyolefin (B) layer 150 μm) were prepared.
<Each extruder and extrusion conditions>
EVOH resin composition (A) extruder: single screw, diameter 40 mm, L / D = 26, temperature 170 ° C. to 210 ° C.
Polyolefin (B) extruder: single screw, screw diameter 40 mm, L / D = 22, temperature 160 ° C. to 210 ° C.
Resin composition (E) extruder: single screw, diameter 65 mm, L / D = 22, temperature 200 ° C. to 240 ° C.
Carboxylic acid modified polyolefin (D) extruder: single screw, diameter 40 mm, L / D = 26, temperature 160 ° C. to 220 ° C.)
<Molding conditions of coextrusion sheet forming apparatus>
Feed block die (width 600mm), temperature 255 ° C

[Production of thermoformed container]
Multi-layer sheet obtained by coextrusion molding device (sampled after 30 minutes and 24 hours after start-up of coextrusion molding device) is cut into 15cm square, and sheet is processed by batch type thermoforming tester manufactured by Asano Manufacturing Co., Ltd. Thermoformed into a cup shape (die shape 70φ × 70 mm, drawing ratio S = 1.0) under conditions of a temperature of 150 ° C. (pressure: 5 kg / cm ² , plug: 45φ × 65 mm, syntax foam, plug temperature: 150 A thermoformed container was produced by performing a mold temperature of 70 ° C.).

[Manufacture of blow molded containers]
<Examples 1-5, Comparative Examples 1 and 2>
Using the EVOH resin composition (A), polyethylene resin (HZ8200B manufactured by Prime Polymer Co., Ltd.), adhesive resin (Admer GT-6A manufactured by Mitsui Chemicals Co., Ltd.), and the resin composition (E), Suzuki Wooden Works Cooling at 210 ° C. and mold temperature 15 ° C. for 20 seconds with a blow molding machine TB-ST-6P, total layer thickness 700 μm ((inner side) polyolefin (B) layer 240 μm / adhesive resin (D) layer 40 μm Molded 3L blow-molded container consisting of 4 types and 6 layers: / EVOH (A) layer 40 μm / adhesive resin (D) layer 40 μm / resin composition (E) layer 100 μm / polyolefin (B) layer 240 μm (outside)) did. The container had a bottom diameter of 100 mm and a height of 400 mm. Here, the resin composition (E) used the resin composition of the collection | recovery frequency 1 time, 5 times, and 10 times as a resin composition (E), respectively.

(8) Evaluation of blow molded container <Appearance evaluation>
About the 3L container which carried out the blow molding using the resin composition 10 times of collection | recovery for the resin composition (E) layer, the streak and coloring were visually evaluated on the following reference | standard, and it was set as the external appearance evaluation.

(Evaluation criteria for streaks)
“Good (A)”: No streak was observed.
“Slightly good (B)”: streaks were confirmed.
“Bad (C)”: Many streaks were confirmed.

(Evaluation criteria for coloring)
“Good (A)”: colorless “Slightly good (B)”: yellowing “Poor (C)”: severely yellowing

<Impact resistance evaluation>
A 3 L container obtained by blow molding using the resin composition having a collection frequency of 1, 5, and 10 as the resin composition (E) layer was filled with 2.5 L of propylene glycol, and the opening was 40 μm of polyethylene / 12 μm of aluminum foil / The film was heat sealed with a film of polyethylene terephthalate 12 μm and covered. The tank was cooled at −40 ° C. for 3 days, dropped from a height of 6 m so that the opening was on top, and evaluated by the number of broken pieces (n = 10).
(Evaluation criteria for impact resistance)
“Good (A)”: less than 3 “Slightly good (B)”: 3 to less than 6 “Poor (C)”: 6 or more

(9) Dispersed particle size of EVOH contained in resin composition (E) layer A blow molded container was carefully cut with a microtome in a direction perpendicular to the container side surface, and a resin composition layer was taken out using a knife. Platinum was deposited on the exposed cross section in a reduced pressure atmosphere. The cross section on which platinum was deposited was magnified 10,000 times using a scanning electron microscope (SEM) and photographed. A region containing about 20 EVOH particles in the photograph was selected, the particle size of each particle image existing in the region was measured, and the average value was calculated to obtain the dispersed particle size. In addition, about the particle size of each particle | grain, the long diameter (longest part) of the particle | grains observed in a photograph was measured, and this was made into the particle size. The film or sheet was cut perpendicularly to the extrusion direction, and the cut surface was photographed from the vertical direction.
(Evaluation criteria for average dispersed particle size)
“Good (A)”: less than 1.5 μm “Slightly good (B)”: less than 2.5 μm “Poor (C)”: 2.5 μm or more

  As shown in Table 1, it was found that the blow-molded container of the present invention was less likely to cause streaking and coloring and was superior in appearance as compared with the comparative example. Moreover, the blow molded container of the present invention was excellent in impact resistance in a multilayer container containing a resin composition that was repeated 10 times. The blow-molded container of the present invention uses a resin composition having excellent repeatability to prevent thickening due to thermal degradation of the EVOH component during repeated collection, and suppresses aggregation of the EVOH component in the resin composition. It was found that the effect of preventing the impact resistance from decreasing is exhibited.

  The present invention can provide a resin composition and a thermoformed container that are suppressed in occurrence of defects in thermoforming, have excellent appearance, and have sufficient strength. Moreover, when the recovered material obtained by repeatedly recovering the sheet edge portion or scrap containing the resin composition is used as a layer in the multilayer structure, thermal degradation or aggregation of EVOH in the recovered material does not occur. There is no deterioration in compatibility with the thermoplastic resin, and a reduction in impact resistance of the obtained multilayer container is suppressed. Therefore, the resin composition, the multilayer structure and the molded product are suitable as molding materials for various packaging materials such as food packaging materials and fuel containers.

Claims (11)

  A resin composition comprising an ethylene-vinyl alcohol copolymer (A), a polyolefin (B), and a saturated ketone (C), wherein the content of the saturated ketone (C) is from 0.01 ppm to 100 ppm.   The resin composition according to claim 1, wherein the saturated ketone (C) has 3 to 8 carbon atoms.   The resin composition according to claim 2, wherein the saturated ketone (C) is selected from the group consisting of acetone, methyl ethyl ketone, and 2-hexanone.   The resin composition according to any one of claims 1 to 3, further comprising an acid-modified polyolefin.   The resin composition according to any one of claims 1 to 4, further comprising a fatty acid metal salt.   The multilayer structure which has a layer which consists of the layer which consists of a resin composition of any one of Claims 1-5, and a layer which consists of another component.   The multilayer structure according to claim 6, wherein the layer made of the other component is a layer made of the ethylene-vinyl alcohol copolymer (A) and a layer made of the polyolefin (B).   A thermoformed container comprising the multilayer structure according to claim 6 or 7.   The thermoformed container according to claim 8, which is a blow molded article.   A method for manufacturing a thermoformed container, comprising a step of thermoforming the multilayer structure according to claim 6. The method for producing a thermoformed container according to claim 10, wherein the thermoforming is a blow molding method.