JP6653728B2 - Resin composition, multilayer structure, thermoformed container and method for producing the same - Google Patents

Description

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

  BACKGROUND ART 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 a film or sheet 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 containing a polyolefin resin or the like. A packaging material containing such an EVOH layer is used as a packaging container by thermoforming. Such a packaging container has an excellent oxygen barrier property by including an EVOH layer, and thus is widely used in various fields requiring an oxygen barrier property, such as foods, cosmetics, medicinal chemicals, and toiletries. At this time, there is a case where an end portion, a defective product, and the like generated at the time of 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 reusing a collected product of a multilayer structure including a polyolefin layer and an EVOH layer, gelation may occur due to thermal deterioration during melt molding, or the deteriorated product may adhere to the inside of the extruder for a long time. It was difficult to carry out continuous melt molding of. Further, when such a deteriorated product adheres to the inside of the extruder, there is a problem that unevenness is generated in the obtained molded product. Furthermore, these problems have become more remarkable as the reuse of the collected material of the multilayer structure is repeated.

  As a measure for solving such a problem, for example, Patent Document 1 discloses a polyolefin; an ethylene-vinyl acetate copolymer soap having an ethylene content of 20 to 65 mol% and a degree of saponification of a vinyl acetate component of 96 mol% or more. At least one compound selected from a metal salt of a higher fatty acid 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 degree of saponification of a vinyl acetate component of 20 % Of a saponified ethylene-vinyl acetate copolymer. Furthermore, it is described that as the metal salt of a higher fatty acid having 8 to 22 carbon atoms, a metal salt of a higher fatty acid such as lauric acid, stearic acid, myristic acid, and the like, and calcium, magnesium, and zinc is preferable. This resin composition has excellent compatibility, and it is said that the surface of a molded product obtained by using this resin composition does not have a wavy pattern and has a beautiful appearance. However, the resin composition containing calcium stearate described in Examples of Patent Literature 1 sometimes causes deposits on the screw, and sometimes causes irregularities in the obtained molded product.

  Patent Document 2 discloses 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 a vinyl acetate component of 95 mol% or more. A method for producing a fuel container, wherein a saponified copolymer is used as an intermediate layer, and a pulverized product of a laminate obtained by laminating a thermoplastic resin on at least both outermost layers is used as a regrind layer (recovery layer). I have. Here, a saponified ethylene-vinyl acetate copolymer containing a fatty acid metal salt is used for the intermediate layer of the laminate used for the regrind layer. As the fatty acid metal salt, at least one selected from a magnesium salt, a calcium salt and a zinc salt is used. In addition, lower fatty acids and / or higher fatty acids are used as fatty acids. According to this manufacturing method, 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 a deteriorated product adheres to the screw at the time of melt-molding the laminate, and unevenness occurs in the obtained molded product.

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

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

  However, crotonaldehyde added during the polymerization is partially consumed in the polymerization step and the saponification step. In addition, 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 production method of EVOH usually includes a step of washing sodium acetate generated by neutralization after saponification with water. 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-mentioned production method, the effect of adding a saturated aldehyde such as improvement in thermal stability and long-time operation characteristics (long run property) in thermoforming is unknown.

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

JP-A-3-72542 JP 2001-348017 A JP 2007-31725 A

  It is an object of the present invention to provide a resin composition and a thermoforming container which suppress generation of defects in thermoforming, have excellent appearance, and have sufficient strength. A further object of the present invention is to provide a thermoforming container having such properties and to provide a production method which is excellent in long-run property. Further, when the recovered material obtained by repeatedly recovering the sheet edge and the scrap etc. containing the resin composition is used as a layer in the multilayer structure, thermal degradation and aggregation of the EVOH in the recovered material do not occur, and other There is no deterioration in compatibility with the thermoplastic resin, and a decrease in impact resistance of the obtained multilayer container is suppressed.

  The invention made to solve the above-mentioned problems includes an ethylene-vinyl alcohol copolymer (A) (hereinafter also referred to as “EVOH (A)”) and a polyolefin (B) (hereinafter also referred to as “PO (B)”). ) And a saturated aldehyde (C), wherein the content of the saturated aldehyde (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), even if the thermoforming device is operated for a long time, generation of kogation in the device can be effectively suppressed, and The operation time can be extended. Further, the present invention provides a multilayer container excellent in impact resistance even when a sheet end portion, a scrap or the like containing the resin composition is repeatedly collected. Although the reason why the resin composition exhibits the above-mentioned effects is not necessarily clear, for example, by containing EVOH (A), PO (B), and saturated aldehyde (C) at the above specific contents, respectively. The effects of containing these components are synergistically exhibited, and as a result, the continuous operation time can be extended.

  The saturated aldehyde (C) preferably has 3 to 8 carbon atoms. As the saturated aldehyde (C), at least one selected from the group consisting of propanal, butanal, and hexanal is preferable. The thermoformed container has excellent appearance and sufficient strength because the EVOH layer (A) contains a specific substance as a saturated aldehyde (C). Further, when the value is less than the lower limit of the saturated aldehyde (C), a decrease in the impact resistance of the multilayer container obtained during long-term continuous operation cannot be suppressed. Further, when the content of the saturated aldehyde (C) exceeds the upper limit, EVOH aggregates by condensing the saturated aldehyde (C) or reacting with the condensate of the EVOH and the saturated aldehyde (C), thereby increasing the viscosity. As a result, the impact resistance is reduced.

  The resin composition may further contain an acid-modified polyolefin. By adding an 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. It is preferable to include a fatty acid metal salt because a multilayer structure or a thermoformed container excellent in appearance and mechanical strength (impact resistance) can be manufactured.

  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 other components is preferable because it has good appearance and impact resistance.

  In the multilayer structure, the layers composed of other components are 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, it is excellent in appearance, impact resistance, processing characteristics, and economy.

  The thermoformed container of the present invention is preferably made of the multilayer structure. Preferably, the thermoformed container is a blow molded article. The thermoformed container is preferably manufactured by a step of thermoforming the multilayer structure, and the thermoforming is preferably a blow molding method. The appearance and impact resistance are excellent by forming the multilayer structure by thermoforming, especially by blow molding.

  As described above, the resin composition of the present invention contains EVOH (A), PO (B) and saturated aldehyde (C), thereby suppressing the occurrence of defects in thermoforming and having an excellent appearance. And a thermoformed container having sufficient strength. Further, the present invention provides a production method which can provide a thermoformed container having such characteristics and is excellent in long-run property. In addition, even when the sheet edge and the scrap containing the resin composition are repeatedly collected, the heat deterioration of the EVOH in the collected material is suppressed, and the appearance and mechanical properties are maintained by maintaining and improving the compatibility with PO. A multilayer structure and a thermoformed container having excellent strength (impact resistance) can be manufactured. The resin composition and the multilayer structure are suitable as molding materials for various thermoforming containers and packaging materials such as bottles, cups, trays and fuel containers because of their excellent appearance, impact resistance and processing characteristics.

  Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto. Unless otherwise specified, the exemplified materials may be used alone or in combination of two or more.

[Resin composition]
The resin composition of the present invention is a resin composition containing EVOH (A), PO (B), and a saturated aldehyde (C), and the content of the saturated aldehyde (C) with respect to the resin composition. Is from 0.01 ppm to 100 ppm. Here, “ppm” is a mass ratio of the corresponding component in the whole resin composition, and 1 ppm is 0.0001% by mass. The resin composition is, as long as the effect of the present invention is not impaired, a boron compound, a phosphorus compound, an aliphatic carboxylic acid, an aliphatic carboxylate, an antioxidant, an ultraviolet absorber, a plasticizer, and an antistatic as optional components. Agents, lubricants, coloring agents, fillers, heat stabilizers, hydrotalcite compounds, and the like. Hereinafter, each component will be described.

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

  Examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl pivalate, and the like, with vinyl acetate being preferred. 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 a monomer include a vinylsilane-based compound and other polymerizable compounds. The content of the other structural units is preferably from 0.0002 mol% to 0.2 mol% with respect to all the structural units of the EVOH (A).

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

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

  The ethylene unit content of EVOH (A) is usually 20 mol% or more and 60 mol% or less, preferably 24 mol% or more and 55 mol% or less, more preferably 27 mol% or more and 45 mol% or less, and more preferably 27 mol% or less. It is more preferably at least 42 mol%, particularly preferably at least 27 mol% and not more than 38 mol%. When the ethylene content is less than 20 mol%, the thermal stability during melt extrusion is reduced, gelation is likely to occur, and defects such as streaks and fish eyes may easily occur. In particular, when operated for a long time under conditions of a higher temperature or a higher speed than those of general melt extrusion, the possibility of gelation increases. On the other hand, when the ethylene content exceeds 60 mol%, the gas barrier properties and the like are reduced, and the advantageous characteristics of EVOH (A) may not be sufficiently 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%, and even more 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)>
The polyolefin (B) used in the present invention is, for example, polyethylene (low density, linear low density, medium density, high density, etc.); ethylene and 1-butene, 1-hexene, 4-methyl-1-pentene, etc. Ethylene-based copolymer obtained by copolymerizing α-olefins or acrylates of the formula: polypropylene; propylene and α-olefins such as ethylene, 1-butene, 1-hexene and 4-methyl-1-pentene are copolymerized Propylene copolymer; poly (1-butene), poly (4-methyl-1-pentene), the above-mentioned polyethylene, ethylene copolymer, polypropylene, propylene copolymer, poly (1-butene) or poly Modified polyolefin obtained by reacting (4-methyl-1-pentene) with maleic anhydride; an ionomer resin and the like. Among them, polypropylene resins such as polypropylene and propylene copolymer, and polyethylene resins such as polyethylene and ethylene copolymer are preferable. As the polyolefin (B), one type may be used alone, or two or more types may be used in combination. In particular, when a multilayer structure having a layer composed of the resin composition of the present invention is used as a food packaging material, a polyethylene-based resin is preferably used from the viewpoint of excellent secondary workability.

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

<Saturated aldehyde (C)>
The resin composition essentially contains a saturated aldehyde (C). The resin composition containing the saturated aldehyde (C) can suppress the occurrence of defects such as gel-like bumps and streaks due to melt molding, and is excellent in appearance.

  Here, the saturated aldehyde (C) refers to an aldehyde containing no unsaturated bond in a portion other than the aldehyde group in the molecule. The saturated aldehyde (C) is an aldehyde having a ring structure in the molecule, whether it is a linear aldehyde or a branched aldehyde, as long as it does not contain an unsaturated bond in a portion other than the aldehyde group. It may be. The number of aldehyde groups in the molecule of the saturated aldehyde (C) may be one or two or more.

  Examples of the saturated aldehyde (C) include acetaldehyde, propanal, butanal, pentanal, hexanal, heptanal, octanal, nonanal, decanal, cyclohexanecarbaldehyde, cyclooctanecarbaldehyde, cyclopentylaldehyde, methylcyclohexanecarbaldehyde, methylcyclopentylaldehyde and the like. No.

  As a carbon number of saturated aldehyde (C), from a viewpoint of improvement in water solubility of saturated aldehyde (C), 3-50 are preferred, 3-15 are more preferred, and 3-8 are still more preferred. Among the exemplified saturated aldehydes (C), propanal, butanal, and hexanal are preferable, and propanal is more preferable, from the viewpoint of suppressing generation and coloring of defects due to melt molding and improving long-run property.

  In the saturated aldehyde (C), some 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 content of the saturated aldehyde (C) 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 aldehyde (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 aldehyde (C) is less than the above lower limit, it is insufficient to suppress an increase in the occurrence of gel-like bumps with time in melt molding. On the other hand, when the content of the saturated aldehyde (C) exceeds the above upper limit, condensation between the saturated aldehydes or cross-linking between EVOH and the condensate between the saturated aldehydes occurs during melt molding, which may cause generation of fish eyes and stripes. And the multilayer structure made of the resin composition may be easily colored.

  The resin composition exhibits an excellent effect of suppressing viscosity increase due to thermal deterioration of the EVOH (A) even when a sheet end portion or scrap containing the resin composition is repeatedly collected. Specifically, by adding a saturated aldehyde (C), in a resin composition with the polyolefin (B), the dispersibility of EVOH at the time of repeated collection is improved, and the mechanical strength, That is, an effect of suppressing a decrease in impact resistance is obtained.

<Acid-modified polyolefin>
The acid-modified polyolefin is added to the resin composition to suppress aggregation of EVOH (A) in the resin composition in a micro region.

  Examples of the acid-modified polyolefin include, for example, an olefin polymer in which an unsaturated carboxylic acid or a derivative thereof is introduced by a chemical bond, and specifically, maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, and the like. 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 maleic anhydride graft-modified copolymers of olefins and vinyl monomers. These olefin polymers can be used alone or in combination of two or more.

  The acid-modified polyolefin is preferably in the range of 1% by mass to 20% by mass, more preferably in the range of 3% by mass to 15% by mass, and still more preferably in the range of 5% by mass to 10% by mass, based on the resin composition.

<Fatty acid metal salt>
By adding the fatty acid metal salt to the resin composition, a multilayer structure or a thermoformed container having excellent appearance and mechanical strength (impact resistance) can be manufactured.

  Examples of the metal salt of a fatty acid include metal salts of higher fatty acids having 10 to 26 carbon atoms, such as lauric acid, stearic acid, myristic acid, behenic acid, and montanic acid, and particularly Group 1, 2 or 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 them, 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, still more preferably from 150 ppm to 5,000 ppm, particularly preferably from 200 ppm to 4,000 ppm, based on the resin composition.

<Optional components>
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 coloring agent, a filler, and a hydrogel. It may contain a talcite compound or the like. 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 fluctuation (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 esters such as triethyl borate and trimethyl borate;
Boric acids such as alkali metal salts or alkaline earth metal salts of boric acids, borax and the like;
Borohydrides and the like. 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. As a maximum of content of a boron compound, 5,000 ppm is preferred, 4,000 ppm is more preferred, and 3,000 ppm is still more preferred. When the content of the boron compound is less than the above lower limit, there is a possibility that torque fluctuation of an extruder or the like cannot be sufficiently suppressed. On the other hand, when 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 the 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 property.

  Examples of the phosphorus compound include various phosphoric acids such as phosphoric acid and phosphorous acid, and phosphates. The phosphate may be in any form of a first phosphate, a second phosphate, and a third phosphate. The cationic species is not particularly limited. The phosphate is preferably an alkali metal salt or an alkaline earth metal salt, more preferably sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and more preferably sodium dihydrogen phosphate. And dipotassium hydrogen phosphate are more preferred.

(Aliphatic carboxylic acid)
In addition to the fatty acid metal salts 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 still more preferable. Acetic acid is particularly preferred.

  The content of the aliphatic carboxylic acid 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, and particularly preferably from 200 ppm to 4,000 ppm. When the content of the aliphatic carboxylic acid is less than 50 ppm, a sufficient effect of preventing coloration cannot be obtained, so that a molded article formed from the resin composition may show yellowing. When the content of the aliphatic carboxylic acid exceeds 10,000 ppm, the resin composition tends to gel during melt molding, particularly during melt molding over a long period of time, and the appearance of a molded product may be poor.

(Aliphatic carboxylate)
In addition to the fatty acid metal salts 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 an acetate is more preferable. Further, both the aliphatic carboxylic acid and the aliphatic carboxylate may be used, more preferably both acetic acid and acetate, and further preferably acetic acid and sodium acetate.

  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, and particularly preferably from 200 ppm to 4,000 ppm. If the content of the aliphatic carboxylate is less than 50 ppm, a sufficient effect of preventing coloration cannot be obtained, so that a molded article formed from the resin composition may show yellowing. When the content of the aliphatic carboxylate exceeds 10,000 ppm, the resin composition tends to gel at the time of melt molding, particularly at the time of melt molding for a long time, and the appearance of the molded product may be poor. .

(Conjugated polyene compound)
The conjugated polyene compound suppresses oxidative deterioration during melt molding. Here, the conjugated polyene compound has a structure in which carbon-carbon double bonds and carbon-carbon single bonds are connected alternately, and has two or more carbon-carbon double bonds. It is a compound having a bond. The conjugated polyene compound may be a conjugated diene having two conjugated double bonds, a conjugated triene having three conjugated double bonds, or a conjugated polyene having more than two conjugated double bonds. Also, a plurality of conjugated double bonds may be present in one molecule without being conjugated to 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 eight or more conjugated double bonds, there is a high possibility that the multilayer body and thus the thermoforming 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, and sulfone groups. And other functional groups such as a salt thereof, a sulfonyl group, a sulfoxide group, a sulfide group, a thiol group, a phosphate group and a salt thereof, a phenyl group, a halogen atom, a non-conjugated double bond, and a triple bond. .

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, chloroprene, 1-chloro-1,3-butadiene, 1-bromo-1,3-butadiene, 2-bromo-1,3-butadiene, ocimene, 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 include conjugated polyene compounds such as cyclooctatetraene, 2,4,6,8-decatetraene-1-carboxylic acid, retinol, and retinoic acid. As the conjugated polyene compound (III), one type may be used alone, or two or more types may be used in combination.

  The carbon number of the conjugated polyene compound is preferably from 4 to 30, more preferably from 4 to 10. Among the exemplified conjugated diene compounds, sorbic acid, sorbic acid ester, sorbate, myrcene, and a mixture of two or more of these are preferable, and sorbic acid, sorbate, and a mixture thereof are more preferable. Sorbic acid, sorbate and a mixture thereof are preferable from the viewpoint of hygiene and availability because they have a high effect of suppressing oxidative degradation at high temperatures and are widely used industrially as food additives.

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

  The lower limit of the content of the conjugated polyene compound in the resin composition is preferably 0.01 ppm, more preferably 0.1 ppm, further preferably 0.5 ppm, and particularly preferably 1 ppm. 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 '-Methylene-bis (4-methyl-6-t-butylphenol), octadecyl-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate and the like.

(UV absorber)
Examples of the ultraviolet absorber include ethylene-2-cyano-3,3′-diphenylacrylate, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, and 2- (2′-hydroxy-3′-). (t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-oxytobenzobenzophenone, and the like. Can be

(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 bis stearoamide, butyl stearate and the like.

(Colorant)
The colorant (also referred to as a “pigment”) is not particularly limited, and various organic pigments and inorganic pigments are employed depending on the intended color of the multilayer structure. Examples of the organic pigment include an azo pigment, a quinacridone pigment, and a phthalocyanine pigment, and one or more of these pigments are used. Examples of the inorganic pigments include titanium oxide, zinc oxide, zinc sulfide, carbon black, lead pigments, cadmium pigments, cobalt pigments, iron pigments, chromium pigments, ultramarine blue, navy blue and the like. Alternatively, two or more kinds are used.

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

(Hydrotalcite)
Hydrotalcite suppresses EVOH deterioration 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, and z are positive numbers, a is 0 or a positive number, 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 them is even more preferred. Among these hydrotalcites, particularly preferred ones are as follows.
_{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 gel formation of the resin composition, one or more heat stabilizers such as the hydrotalcite-based compound, the hindered phenol-based compound, and the hindered amine-based compound are used in an amount of 0.01% by mass to 1% by mass. % 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 aldehyde (C) can be uniformly blended.

Examples of the method of uniformly blending the saturated aldehyde (C) with the above-mentioned specific content in the resin composition in the resin composition include, for example, (1) a step of copolymerizing ethylene and a 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 causing the resin composition to contain a specific amount of the saturated aldehyde (C) is not particularly limited. For example, a method of adding the specific amount of the saturated aldehyde (C) in the step (1),
A method of adding a specific amount of a saturated aldehyde (C) in the step (2),
A method of adding a specific amount of a saturated aldehyde (C) to the EVOH (A) obtained in the above step (2),
A method of adding a specific amount of a saturated aldehyde (C) when blending the EVOH (A) obtained in the above step (2) with the polyolefin (B),
A method using these methods in combination is exemplified.

  When the method of adding a specific amount of saturated aldehyde (C) in the above step (1) or the method of adding a specific amount of saturated aldehyde (C) in the above step (2) is adopted, the above method ( It is necessary to add it within a range that 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 control of the content of the saturated aldehyde (C) in the resin composition, a specific amount of the saturated aldehyde (C) is added to the EVOH (A) obtained in the step (2). The method of adding a specific amount of a saturated aldehyde (C) when blending the EVOH (A) obtained in the step (2) with the polyolefin (B) is preferable, and the method obtained in the step (2) is preferred. A method of adding a specific amount of a saturated aldehyde (C) to the EVOH (A) is more preferable.

  As a method for adding a specific amount of the saturated aldehyde (C) to the EVOH (A), for example, a method in which the saturated aldehyde (C) is blended in advance with the EVOH (A) to granulate a pellet, a method for ethylene-vinyl ester copolymerization, A method of impregnating saturated aldehyde (C) into a strand deposited in a step of depositing a paste after the saponification of the coalesced, a method of impregnating a saturated aldehyde (C) after cutting the deposited strand, and a chip of a dried resin composition A method in which a saturated aldehyde (C) is added to a solution obtained by re-dissolving the above, a method in which a mixture of two components of EVOH (A) and a saturated aldehyde (C) is melt-kneaded, and a method in which EVOH (A) is melted in the middle of an extruder A method of feeding a saturated aldehyde (C) to a product and mixing a high concentration of a saturated aldehyde (C) with a part of the EVOH (A). How to grain dry blending to melt kneading to create a masterbatch and EVOH (A) was, and the like.

  Among these, from the viewpoint that a trace amount of the saturated aldehyde (C) can be more uniformly dispersed in the EVOH (A), the saturated aldehyde (C) is blended in advance with the EVOH (A) to pelletize the pellet. The method is preferred. Specifically, a saturated aldehyde (C) is added to a solution obtained by dissolving EVOH (A) in a good solvent such as a water / methanol mixed solvent, and the mixed solution is extruded from a nozzle or the like into a poor solvent to cause precipitation and precipitation. By pelletizing and / or washing and / or drying, pellets in which the saturated aldehyde (C) is uniformly mixed with the EVOH (A) can be obtained.

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

  Among them, as shown in Examples described later, generally, a single-screw or twin-screw extruder used for melt-blending a resin is most preferable. The order of addition is not particularly limited, and the resin component containing the EVOH (A) and the saturated aldehyde (C), the PO (B) and the fatty acid metal salt are simultaneously or appropriately placed in an extruder and melt-kneaded. Is preferably adopted. Further, an optional component may be added at the time of melt-kneading.

[Multilayer structure]
The multilayer structure of the present invention may have at least one layer obtained by melt-molding the above resin composition and at least one layer and a layer composed of other components. The ratio, the type of resin used for the other layers, the presence or absence of the 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 above-mentioned polyolefin (B). Examples of the polyolefin (B) include polypropylene resins such as polypropylene and propylene copolymers, and polyethylene and ethylene copolymers. Polyethylene resins such as polymers are preferred

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

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

  As a method for producing a multilayer structure, among these, 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 a layer composed of other components by the above method, the resin composition layer can be easily and reliably manufactured, and as a result, good appearance, impact resistance and processing characteristics are effectively improved. Can be achieved.

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

[Production method of molded article]
Examples of a method for molding a molded article using the multilayer structure include a vacuum molding method, a pressure molding method, a vacuum pressure molding method, and a blow molding method. These moldings are usually performed in a temperature range equal to or lower than 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 by using both vacuum and pressure. The molded article can be easily and reliably manufactured by being formed by the vacuum pressure molding method using the above-described multilayer structure, and as a result, is excellent in appearance and impact resistance.

  The melting temperature varies depending on the melting point of the EVOH (A) and the like, but is preferably about 150 ° C to 250 ° C. If the molding temperature of the EVOH (A) exceeds 250 ° C., the thermal degradation of the EVOH is accelerated, and during repeated collection, poor appearance and impact resistance due to the thermal degradation are induced.

  Extrusion 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., and the temperature of the extruder for forming the resin composition layer is, for example, 200 ° C. to 240 ° C. to form a layer composed of other components. The temperature of the extruder for forming the adhesive layer is, for example, 200 ° C. to 240 ° C., and the temperature of the extruder for forming the adhesive layer is, for example, a temperature of 160 ° C. to 220 ° C.

  Further, the multilayer structure may be subjected to secondary processing according to the desired shape. Examples of the secondary processing include 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, any of a simultaneous biaxial stretching method and a sequential biaxial stretching method can be adopted. Examples of the thermoforming include a method of forming a film or sheet-like multilayer structure into a cup or tray by vacuum forming, pressure forming, vacuum pneumatic forming, or the like. In addition, as the blow molding, a method of molding a parison-shaped multilayer structure into a bottle or a tube by blowing may be used.

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

  Since the molded article has a layer formed from the resin composition having the above-described properties, it can be suitably used for a thermoformed 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 if necessary to form a container, filled with the contents in the container, transported, and used for storage. . As the content, any of foods and non-foods can be used, and any of a dried product, a product containing water, and a product containing oil may be used. Further, the container having the multilayer structure can be subjected to a boil treatment and a retort treatment. In this case, a material in which polypropylene is used for both outer layers or a material having a thick EVOH layer is suitably used.

(1) Measurement of water content of water-containing EVOH pellets Water content of water-containing EVOH pellets was measured using a halogen water content 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 water content of the water-containing EVOH shown below is% by mass based on the dry mass of EVOH.

(2) EVOH ethylene content of (A) and a saponification degree of nuclear magnetic resonance apparatus (Superconducting nuclear magnetic resonance apparatus "Lambda500", manufactured by JEOL Ltd.) was used, a _{DMSO-d 6} as the measuring ^solvent, 1 H- Determined by NMR.

(3) Determination of Saturated Aldehyde (C) To 200 mg of a 50% by mass aqueous solution of 2,4-dinitrophenylhydrazine (DNPH) was added 50 mL of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and acetic acid. 11.5 mL and 8 mL of ion-exchanged 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 and dissolved at 35 ° C. for 1 hour. After acetonitrile was added to this solution to precipitate and precipitate a resin component, the solution obtained by filtration was concentrated to obtain an extracted sample. Saturated aldehyde (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 sample obtained by reacting each saturated aldehyde (C) with a DNPH preparation solution was used.
(Measurement condition)
Column: TSKgel ODS-80Ts (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 were obtained by removing coarse particles using a sieve having a nominal size of 0.150 mm (100 mesh) (based on JIS Z8801-1 to 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 in the extract was quantitatively analyzed by high performance liquid chromatography to determine the amount of the conjugated polyene compound. In the quantification, a calibration curve prepared using a sample of each conjugated polyene compound was used.

(5) Odor at the time of molding 20 g of sample pellets of the resin composition were put into a 100 mL glass sample tube, the mouth was covered with aluminum foil, and then heated at 220 ° C. for 30 minutes in a hot air dryer. After being taken out of the dryer and allowed to cool at room temperature for 30 minutes, the sample tube was shaken two or three times, and then the lid of the aluminum foil was removed to check the odor. The odor intensity of the sample pellet was evaluated according to the following criteria.

A: No odor B: Low odor C: Clear odor

(6) Quantification of Aliphatic Carboxylic Acids (Fatty Acid Salts, Aliphatic Carboxylic Acid Ions of Aliphatic Carboxylates) Dry EVOH pellets, resin compositions or resin compositions subjected to a recovery operation were pulverized by freeze-pulverization. The obtained pulverized material was divided by a sieve having a nominal size of 1 mm (based on standard sieve standard JIS Z8801-1 to 3). 10 g of the pulverized material powder passed through the above sieve and 50 mL of ion-exchanged water were charged into a 100 mL Erlenmeyer flask with a stopper, attached with a cooling condenser, and stirred at 95 ° C. for 10 hours. 2 mL of the obtained solution was diluted with 8 mL of ion-exchanged water. The amount of carboxylate ion is determined from the diluted solution by using the ion chromatography “ICS-1500” manufactured by Yokogawa Electric Corporation according to the following measurement conditions to obtain an aliphatic carboxylic acid (and aliphatic carboxylate ion). Was calculated. In the determination, a calibration curve prepared using each carboxylic acid was used.

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

(7) Quantification of Metal Ions 0.5 g of dried EVOH pellets, a resin composition, or a resin composition subjected to a recovery operation were charged into a pressure-resistant container made of ACTAC fluorocarbon resin, and 5 mL of nitric acid for precision analysis manufactured by Wako Pure Chemical Industries was added. Added more. After standing for 30 minutes, the container was covered with a cap lip with a rupture disk, and treated at 150 ° C. for 10 minutes and then at 180 ° C. for 10 minutes using a microwave high-speed decomposition system “Speedwave MWS-2” manufactured by Actuak. Disassembled. When the decomposition of the resin was not completed, the processing conditions were appropriately adjusted. The obtained decomposed product was diluted with 10 mL of ion-exchanged water, all liquids were transferred to a 50-mL volumetric flask, and the volume was adjusted with ion-exchanged water to obtain a decomposed product solution.
The decomposition product solution obtained above was quantitatively analyzed at each of the following observation wavelengths using an ICP emission spectrophotometer “Optima 4300 DV” manufactured by PerkinElmer Japan, and the amounts of metal ions, phosphate compounds and boron compounds were determined. Was quantified. The amount of the phosphoric acid compound was determined by quantifying the phosphorus element and calculating as a phosphorus element-converted mass. The content of the boron compound was calculated as mass in terms of boron element.
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>
The polymerization of the ethylene-vinyl acetate copolymer was carried out under the following conditions using a 250 L pressure reactor.
83.0 kg of vinyl acetate,
26.6 kg of methanol,
Supply amount 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 3.6MPa
Polymerization time 5.0 hours The polymerization rate of vinyl acetate in the obtained copolymer was about 40%. After sorbic acid was added to the copolymerization reaction liquid, it was supplied to an extrusion tower, and unreacted vinyl acetate was removed from the top of the tower by introduction of methanol vapor from the lower part of the tower to obtain 41% of ethylene-vinyl acetate copolymer. % Methanol solution was obtained. The ethylene content of this ethylene-vinyl acetate copolymer was 32 mol%. This methanol solution of the ethylene-vinyl acetate copolymer is charged into a saponification reactor, and a sodium hydroxide / 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 to be precipitated, and cut to obtain a pellet having a diameter of about 3 mm and a length of about 5 mm. The operation of removing the obtained pellet with a centrifuge and further adding a large amount of water to remove the liquid was repeated.

[Preparation of EVOH resin composition]
20 kg of the above-dehydrated 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. Saturated aldehyde (C) was added to the obtained solution, and the mixture was further stirred for 1 hour to completely dissolve the saturated aldehyde (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 coagulate 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 aqueous acetic acid solution and ion-exchanged water. After the washing liquid and the EVOH resin composition chip were separated and drained, they were placed in a hot air drier, 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 determined by the above method.

[Preparation of resin composition]
<Example 1>
5.5 parts of EVOH resin composition (A), 87 parts of polyethylene as polyolefin (B) (HZ8200B manufactured by Prime Polymer Co., Ltd .; hereinafter referred to as HDPE), acid-modified polyolefin (D) (Admer GT- manufactured by Mitsui Chemicals, Inc.) 6A. Hereinafter, referred to as AD.) 7.5 parts and 0.15 part of a fatty acid metal salt were mixed, and a saturated aldehyde (C) was added as necessary to obtain a mixture.
The mixture was melt-kneaded under the following pelletizing conditions to obtain 20 kg of a resin composition having a composition shown in Table 1 (hereinafter, referred to as a resin composition (E)). The operations of melt-kneading the obtained resin composition again and taking out from the kneader were repeated, and the number of times of melt-kneading (hereinafter, referred to as the number of times of collection) was 5 times, and 10 kg of the resin composition (E) was also obtained in an amount of 20 kg. Was. The melting and kneading temperature of the resin composition (E) was 250 ° C., which is higher than usual, while the usual kneading temperature of EVOH is about 150 ° C. to 250 ° C. The content of the saturated aldehyde (C) was determined by the method described above. The content of the fatty acid metal salt was determined by adjusting the mass of the mixture.
(Pelletizing conditions)
Extruder: Twin screw extruder “Laboplast Mill” manufactured by Toyo Seiki Seisaku-sho, Ltd.
Screw diameter: 25mmφ
Screw rotation speed: 100 rpm
Feeder rotation speed: 100 rpm
Cylinder and 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>
The mixture shown in Table 1 was prepared, and a resin composition was prepared in the same manner as in Example 1.

[Preparation 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 Co., Ltd.), and resin composition (E ) In separate extruders, and a multilayer sheet having a total layer thickness of 1000 μm and comprising 4 types and 6 layers (layer structure: polyolefin (B) layer 300 μm / carboxylic acid-modified polyolefin (D) 50 μm / EVOH (A) layer 50 μm / A carboxylic acid-modified polyolefin (D) 50 μm / resin composition (E) layer 400 μm / polyolefin (B) layer 150 μm) was prepared.
<Each extruder and extrusion conditions>
Extruder for EVOH resin composition (A): single screw, diameter 40 mm, L / D = 26, temperature 170 ° C. to 210 ° C.
Extruder for polyolefin (B): single screw, screw diameter 40 mm, L / D = 22, temperature 160 ° C to 210 ° C
Extruder for resin composition (E): single screw, diameter 65 mm, L / D = 22, temperature 200 ° C. to 240 ° C.
Extruder for carboxylic acid-modified polyolefin (D): single screw, diameter 40 mm, L / D = 26, temperature 160 ° C. to 220 ° C.)
<Molding conditions for co-extrusion sheet molding machine>
Feed block type die (600mm width), temperature 255 ℃

[Production of thermoformed container]
The multilayer sheet obtained by the co-extrusion molding apparatus (sampled 30 minutes and 24 hours after the start of the co-extrusion molding apparatus) was cut into 15 cm squares, and the sheet was formed by a batch-type thermoforming test machine manufactured by Asano Manufacturing Co., Ltd. Under the condition of a temperature of 150 ° C., thermoforming into a cup shape (mold shape 70φ × 70 mm, drawing ratio S = 1.0) (pressurized air: 5 kg / cm ² , plug: 45φ × 65 mm, syntax foam, plug temperature: 150) ° C, mold temperature: 70 ° C) to produce a thermoformed container.

[Manufacture of blow molded containers]
<Examples 1 to 5, Comparative Examples 1 and 2>
Using the above EVOH resin composition (A), polyethylene resin (HZ8200B made by Prime Polymer Co., Ltd.), adhesive resin (Admer GT-6A made by Mitsui Chemicals, Inc.), and the above resin composition, blow molding made by Suzuki Kogyo After cooling at 210 ° C. and a mold temperature of 15 ° C. for 20 seconds with a TB-ST-6P machine, the total layer thickness was 700 μm ((inside) polyolefin (B) layer 240 μm / adhesive resin (D) layer 40 μm / EVOH ( (A) layer 40 μm / adhesive resin (D) layer 40 μm / resin composition (E) layer 100 μm / polyolefin (B) layer 240 μm (outside)). The bottom diameter of this container was 100 mm, and the height was 400 mm. Here, as the resin composition (E), the number of times of collection was 1, 5 and 10 times, respectively, and the resin composition was used as the resin composition (E).

(8) Evaluation of blow molded container <Appearance evaluation>
For the 3 L container blow-molded using the resin composition of the 10th collection for the resin composition (E) layer, streaks and coloring were visually evaluated according to the following criteria, and the appearance was evaluated.

(Streak evaluation criteria)
"Good (A)": No streak was observed.
"Slightly good (B)": Streaks were observed.
"Bad (C)": Many streaks were observed.

(Evaluation criteria for coloring)
"Good (A)": colorless "Slightly good (B)": yellowing "Poor (C)": severe yellowing

<Evaluation of impact resistance>
2.5 L of propylene glycol was filled into a 3 L container blow-molded using the resin composition for the resin composition (E) layer with the number of times of collection 1, 5 and 10 times, and the opening was polyethylene 40 μm / aluminum foil 12 μm / The film was heat-sealed with a film having a structure of polyethylene terephthalate of 12 μm and capped. The tank was cooled at −40 ° C. for 3 days, dropped from a height of 6 m with the opening facing upward, and evaluated by the number of pieces broken (n = 10).
(Evaluation criteria for impact resistance)
“Good (A)”: less than 3 “Slightly good (B)”: 3 to less than 6 “Bad (C)”: 6 or more

(9) Dispersion particle size of EVOH contained in the resin composition (E) layer The blow molded container was carefully cut with a microtome in a direction perpendicular to the side surface of the container, and the resin composition layer was taken out using a scalpel. Platinum was deposited on the exposed cross section under a reduced pressure atmosphere. The cross section on which platinum was deposited was photographed at a magnification of 10,000 times using a scanning electron microscope (SEM). A region containing about 20 EVOH particles in this photograph was selected, the particle size of each particle image present in the region was measured, the average value was calculated, and this was used as the dispersed particle size. In addition, about the particle diameter of each particle, the long diameter (longest part) of the particle observed in a photograph was measured, and it was set as the particle diameter. The film or sheet was cut perpendicular to the extrusion direction, and a photograph was taken of the cut surface from the vertical direction.
(Evaluation criteria for average dispersed particle size)
“Good (A)”: less than 1.5 μm “Somewhat good (B)”: less than 2.5 μm “Bad (C)”: 2.5 μm or more

  As shown in Table 1, it was found that the blow-molded container of the present invention suppressed generation of streaks and coloring and was excellent in appearance as compared with the comparative example. Further, the blow molded container of the present invention was excellent in impact resistance in a multilayer container containing the resin composition which was repeated 10 times. The blow-molded container of the present invention uses a resin composition having excellent retrievability repeatedly to prevent thickening due to thermal deterioration of the EVOH component during repeated collection and to suppress aggregation of the EVOH component in the resin composition. It was found that the composition exhibited an effect of preventing the impact resistance from decreasing.

  ADVANTAGE OF THE INVENTION This invention can provide the resin composition and thermoforming container which generate | occur | produce the defect in thermoforming, are excellent in appearance, and have sufficient intensity | strength. Further, when the recovered material obtained by repeatedly recovering the sheet edge and the scrap etc. containing the resin composition is used as a layer in the multilayer structure, thermal deterioration and aggregation of the EVOH in the recovered material do not occur, and other There is no deterioration in compatibility with the thermoplastic resin, and a decrease in impact resistance of the obtained multilayer container is suppressed. Therefore, the resin composition, the multilayer structure, and the molded article are suitable as molding materials for various packaging materials for food packaging materials, fuel containers, and the like.

Claims (9)

It contains an ethylene-vinyl alcohol copolymer (A), a polyolefin (B), and a saturated aldehyde (C), and the saturated aldehyde (C) is propanal, and the content of the propanal is 0.1 ppm or more and 20 ppm. Is the following ,
The ethylene - Ri average dispersed particle diameter is 2.5μm less than Der vinyl alcohol copolymer (A),
A resin composition further containing a zinc salt of a fatty acid . The resin composition according to claim 1, wherein the content of the zinc salt of the fatty acid is 50 ppm or more and 4,000 ppm or less . The resin composition according to claim 1, further comprising an acid-modified polyolefin. Multilayer structure having a layer comprising a layer and other components of the resin composition according to any one of claims 1-3. The multilayer structure according to claim 4 , wherein the layers composed of other components are a layer composed of the ethylene-vinyl alcohol copolymer (A) and a layer composed of the polyolefin (B). Thermoformed container made of a multilayer structure according to claim 4 or claim 5. The thermoformed container according to claim 6 , which is a blow molded product. A method for producing a thermoformed container, comprising a step of thermoforming the multilayer structure according to claim 4 or 5 . The method for producing a thermoformed container according to claim 8 , wherein the thermoforming is a blow molding method.