JP6454461B2 - Resin composition, resin molded body and multilayer structure - Google Patents

Description

  The present invention relates to a resin composition, a resin molded body, and a multilayer structure.

  For molding containers, films, sheets, etc., melt molding using a resin composition is generally used. Such a resin composition can form a molded product having few defects such as streak and fish eye and excellent in appearance, and long-time operation characteristics (long run property) in which the above defects are not easily generated even after long-time melt molding. ) Is required. In particular, such defects not only impair the appearance of the molded product, but also cause performance deterioration, so it is important to suppress the occurrence of defects.

  On the other hand, an ethylene-vinyl alcohol copolymer (hereinafter also referred to as “EVOH”) is a polymer material excellent in gas shielding properties such as oxygen, oil resistance, non-charging property, mechanical strength, and the like. Therefore, the EVOH-containing resin composition is widely used as a molding material for molded articles such as containers.

  However, since EVOH has a relatively active hydroxyl group in the molecule, oxidation and cross-linking reaction may occur in a high-temperature melt state even in an extruder with almost no oxygen, which may cause a thermally deteriorated product. In particular, when a long-term continuous operation is performed, a thermally deteriorated material accumulates inside the molding machine, and gel-like spots that cause fish eyes are likely to occur. For this reason, in the melt molding using the EVOH-containing resin composition, the long run property tends to be insufficient.

  In order to improve such inconvenience, various EVOH-containing resin compositions have been developed. For example, an EVOH-containing resin composition (see Japanese Patent Application Laid-Open No. 11-60874) that has improved long-run properties during melt molding by containing a boron compound, sodium acetate, and magnesium acetate, and melted by containing a conjugated polyene compound EVOH-containing resin composition (see Japanese Patent Application Laid-Open No. 9-71620) in which generation of gel-like particles due to molding is suppressed, a specific carboxylic acid metal salt, and a hindered phenol-based antioxidant are included to improve heat stability. An EVOH-containing resin composition (see Japanese Patent Application Laid-Open No. 4-227744) that is excellent in suppressing the formation of an oxidizing gel at high temperatures has been developed.

  However, these conventional EVOH-containing resin compositions are not only sufficiently improved in long-run properties, but when a large amount of metal salt is contained in the resin composition, the molded product tends to yellow and poor appearance tends to occur. In addition, from the viewpoint of environmental measures, for example, reducing the amount of raw materials and waste of molded products such as packaging materials, it is required to make the molded products thinner. In the case of realizing such a thinning, since appearance defects are likely to occur, there is a need for further improvement in appearance. In addition, from the environmental point of view, it is necessary to consider the odor during molding.

Japanese Patent Laid-Open No. 11-60874 JP-A-9-71620 JP-A-4-227744 JP 2007-31725 A JP 2001-72823 A

  The present invention has been made based on the circumstances as described above, and its purpose is excellent in the long run property of melt molding, and generation of defects such as streaks and fish eyes and coloring are suppressed, and the appearance is excellent. It is to provide a resin composition, a resin molded body, and a multilayer structure that can form a molded product while suppressing generation of odor.

  The invention made to solve the above-mentioned problems contains an ethylene-vinyl alcohol copolymer (A) (hereinafter also referred to as “EVOH (A)”) and a saturated aldehyde (B), and this saturated aldehyde (B) Is a resin composition having a content of 0.01 ppm to 100 ppm.

  When the resin composition contains EVOH (A) and a specific amount of saturated aldehyde (B), generation of defects such as streaks and fish eyes due to melt molding and coloring are suppressed, and the appearance of the molded product is excellent. Thereby, it can respond to the request | requirement of thickness reduction, suppressing the deterioration of an external appearance, and can contribute to reduction of a raw material and a waste amount. In addition, the resin composition hardly has defects and odors even after long-time melt molding, and has a sufficiently long run property.

  Although the effect of suppressing the occurrence of defects by containing a specific amount of saturated aldehyde (B) is not necessarily clear, it is considered that saturated aldehyde (B) is more easily oxidized than EVOH (A). . That is, it is presumed that heat-degraded products such as gel-like materials are generated due to oxidative degradation of EVOH (A), but the saturated aldehyde (B) is oxidized earlier than EVOH (A), so It is estimated that the occurrence is suppressed.

  The saturated aldehyde (B) preferably has 3 to 8 carbon atoms. The saturated aldehyde (B) is preferably at least one selected from the group consisting of propanal, butanal and hexanal. By containing a specific saturated aldehyde as the saturated aldehyde (B) in this manner, generation of defects and coloration due to melt molding are further suppressed, and thus the appearance of the molded product is more excellent.

  The resin composition may further contain a boron compound. The boron compound content is preferably 100 ppm or more and 5,000 ppm or less. By further containing a specific amount of the boron compound as described above, generation of gel-like particles during melt molding can be suppressed, and torque fluctuation (viscosity fluctuation during heating) of an extruder or the like can be suppressed. Thereby, while being able to form molded articles, such as a container excellent in an external appearance property, long run property can be improved more.

  The resin composition may further contain a conjugated polyene compound. The content of the conjugated polyene compound is preferably 0.01 ppm or more and 1,000 ppm or less. Thus, the oxidation deterioration at the time of melt molding can be suppressed by further containing a specific amount of the conjugated polyene compound. Thereby, since generation | occurrence | production and coloring of a defect can be suppressed more, while being able to form the molded article which is excellent in external appearance property, long run property can be improved more.

  The conjugated polyene compound is preferably at least one of sorbic acid and sorbate. Thus, by containing sorbic acid or sorbate, the oxidative deterioration at the time of melt molding can be suppressed more effectively. Thereby, since generation | occurrence | production and coloring of a defect can be suppressed further, while being able to improve the external appearance property of a molded article, long run property can be improved more.

  The resin composition may further contain at least one of acetic acid and acetate. The total content of acetic acid and acetate is preferably 50 ppm to 1,000 ppm. Thus, coloring of a molded article can be prevented more by further containing a specific amount of acetic acid.

  The resin composition may further contain a phosphorus compound. The phosphorus compound content is preferably 1 ppm or more and 200 ppm or less. By further containing a specific amount of the phosphorus compound as described above, generation of defects and coloring can be further suppressed, so that the appearance of the molded product can be further improved and the long run property can be further improved.

  The present invention includes a resin molded body and a multilayer structure formed from the resin composition. Since these resin molded bodies and multilayer structures are formed from the resin composition, generation and accumulation of thermally deteriorated products during melt molding are suppressed. Therefore, when the resin molded body and the multilayer structure are formed, the thermally deteriorated material is prevented from staying and adhering inside and outside the die, so that the resin molded body and the multilayer structure formed during a long continuous operation can be obtained. Even the appearance is excellent.

  Since the resin composition of this invention can suppress generation | occurrence | production and the coloring of the defect at the time of melt molding, it can provide the molded article which is excellent in external appearance property. Further, the resin composition is excellent in long-run property because defects and odor are hardly generated even after long-time melt molding. Therefore, the said resin composition is shape | molded in a container, a film, a sheet | seat, etc., The molded object can be used suitably as a multilayer structure and various packaging materials.

  Embodiments of the present invention will be described below. However, the present invention is not limited to the following description. Moreover, as long as there is no description in particular, the material illustrated below may be used individually by 1 type, and may use 2 or more types together.

<Resin composition>
The resin composition contains EVOH (A) and saturated aldehyde (B). This resin composition may further contain a boron compound, a conjugated polyene compound, acetic acid or a phosphorus compound as a suitable component. The resin composition may contain other optional components as long as the effects of the present invention are not impaired. Hereinafter, EVOH (A), saturated aldehyde (B), boron compound, conjugated polyene compound, acetic acid, phosphorus compound and other optional components will be described in detail.

  Here, “ppm” is a mass ratio of the corresponding component in the resin composition, and 1 ppm is 0.0001 mass%. “Content of boron compound” is the content as boric acid equivalent mass. The “acetate content” is the content as acetic acid equivalent mass. The “content of phosphorus compound” is the content as phosphorus element equivalent mass.

[EVOH (A)]
EVOH (A) is an ethylene and 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 monomer units other than ethylene and vinyl ester. Examples of such monomer units 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-methoxy-ethoxy) silane, and γ-methacryloxypropyltrimethoxysilane. 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 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 more. 42 mol% or less is still more preferable, and 27 mol% or more and 38 mol% or less are especially preferable. 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 higher temperature or at a higher speed than the general melt extrusion conditions, the possibility of gelation increases. On the other hand, when the ethylene content exceeds 60 mol%, gas barrier properties and the like are lowered, and there is a possibility that the advantageous properties possessed by EVOH cannot be sufficiently exhibited.

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

  As content of EVOH (A) in the said resin composition, it is 95 mass% or more normally, 98.0 mass% or more is preferable, 99.0 mass% is more preferable, 99.5 mass% or more is further more preferable. . By setting the EVOH (A) content to 95% by mass or more, the advantageous properties possessed by EVOH can be sufficiently exerted, and thus molded articles obtained from the resin composition are excellent in gas shielding properties, oil resistance, and the like. .

[Saturated aldehyde (B)]
The saturated aldehyde (B) suppresses the occurrence of defects such as streaks and fish eyes due to melt molding and coloring, and improves long run properties. Here, the saturated aldehyde (B) refers to an aldehyde that does not contain an unsaturated bond in a portion other than the aldehyde group in the molecule. Saturated aldehyde (B) is an aldehyde having a ring structure in the molecule, whether it is a linear aldehyde or a branched aldehyde, as long as it contains no 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 (B) may be 1 or 2 or more.

  Examples of the saturated aldehyde (B) include acetaldehyde, propanal, butanal, pentanal, hexanal, heptanal, octanal, nonanal, decanal, cyclohexanecarbaldehyde, cyclooctanecarbaldehyde, cyclopentylaldehyde, methylcyclohexanecarbaldehyde, methylcyclopentylaldehyde, and the like. Can be mentioned.

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

  In the saturated aldehyde (B), 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 content of the saturated aldehyde (B) 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 (B) 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 (B) is less than the above lower limit, the effect of containing the saturated aldehyde (B), for example, the occurrence of defects and the effect of suppressing coloring cannot be sufficiently obtained. On the other hand, if the content of the saturated aldehyde (B) exceeds the above upper limit, oxidation and cross-linking with the saturated aldehyde (B) of the resin composition at the time of melt molding are likely to occur, which may induce the formation of gel-like spots. In addition, the resin composition is easily colored.

[Boron compounds]
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.

  The lower limit of the boron compound content in the resin composition is preferably 100 ppm, more preferably 150 ppm. 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 is likely to occur during melt molding, and the appearance of the molded product may be deteriorated.

[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. Further, a plurality of sets of the 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 a conjugated polyene compound having 8 or more conjugated double bonds is contained, there is a high possibility that the molded product will be colored.

  In addition to conjugated double bonds, the conjugated polyene compounds include 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, sulfones. It may have other functional groups such as a group and 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 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, 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-butyl Tadiene, 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. The said conjugated polyene compound 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 EVOH (A) may be deteriorated, and the appearance after melt molding may be deteriorated.

  As a minimum of content of the conjugated polyene compound of the 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.

[Acetic acids]
Acetic acids prevent coloring of the molded product and suppress gelation during the prevention melt molding. The acetic acids include acetic acid and acetate. As acetic acid, it is preferable to use acetic acid and acetate together, and it is more preferable to use acetic acid and sodium acetate together.

  As a minimum of content of acetic acid in the resin composition concerned, 50 ppm is preferred, 100 ppm is more preferred, 150 ppm is still more preferred, and 200 ppm is especially preferred. The upper limit of the acetic acid content is preferably 1,000 ppm, more preferably 500 ppm, and still more preferably 400 ppm. If the acetic acid content is less than the above lower limit, a sufficient anti-coloring effect cannot be obtained, and the molded product may be yellowed. On the other hand, if the content of acetic acid exceeds the above upper limit, gelation tends to occur during melt molding, particularly during long melt molding, and the appearance of the molded product may be deteriorated.

[Phosphorus compounds]
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 phosphates such as phosphoric acid and phosphorous acid.

  As said phosphate, any form of a 1st phosphate, a 2nd phosphate, and a 3rd phosphate may be sufficient. Moreover, although it does not specifically limit also about the cation seed | species of a phosphate, An alkali metal salt and alkaline-earth metal salt are preferable, Among these, sodium dihydrogen phosphate, potassium dihydrogen phosphate, hydrogen phosphate 2 Sodium and dipotassium hydrogen phosphate are more preferable, and sodium dihydrogen phosphate and dipotassium hydrogen phosphate are more preferable.

  As a minimum of content of a phosphorus compound in the resin composition, 1 ppm is preferred, 2 ppm is more preferred, 3 ppm is still more preferred, and 5 ppm is especially preferred. As an upper limit of content of a phosphorus compound, 200 ppm is preferable, 150 ppm is more preferable, and 100 ppm is further more preferable. When the content of the phosphorus compound is less than the above lower limit or exceeds the above upper limit, the thermal stability is reduced, and there is a risk that gelled spots and coloration are likely to occur during long-time melt molding. .

[Other optional ingredients]
The resin composition may contain other optional components as long as the effects of the present invention are not impaired. Other optional components include, for example, alkali metals or salts thereof, antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, heat stabilizers, other resins, and higher aliphatic carboxylic acids. And metal salts thereof. The resin composition may contain 12 or more of these optional components, and the total content of the optional components is preferably 1% by mass or less in the resin composition.

  Examples of the alkali metal include lithium, sodium, and potassium. Examples of the alkali metal salts include monovalent metal aliphatic carboxylates, aromatic carboxylates, metal complexes, and the like. Specifically, sodium acetate, potassium acetate, sodium stearate, Examples include potassium stearate and sodium salt of ethylenediaminetetraacetic acid. Among these, sodium acetate and potassium acetate are preferable. The alkali metal content in the resin composition is preferably 20 ppm to 1,000 ppm, more preferably 50 ppm to 500 ppm.

  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-tert-butylphenol), octadecyl-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate, 4,4′-thiobis -(6-t-butylphenol) and the like.

  Examples of the ultraviolet absorber include ethylene-2-cyano-3,3′-diphenyl acrylate, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-). Methylphenyl) benzotriazole, 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.

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

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

  Examples of the lubricant include ethylene bisstearamide and butyl stearate.

  Examples of the colorant include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, and bengara.

  Examples of the filler include glass fiber, wollastonite, calcium silicate, talc, and montmorillonite.

  Examples of the heat stabilizer include hindered phenol compounds and hindered amine compounds.

  Examples of the other resin include polyamide and polyolefin.

  Examples of the metal salt of the higher aliphatic carboxylic acid include calcium stearate and magnesium stearate.

  In addition, as a countermeasure against gelation, for example, hindered phenol compounds and hindered amine compounds exemplified as the heat stabilizer, metal salts of the higher fatty acid carboxylic acids, hydrotalcite compounds, and the like may be added. These may be used alone or in combination of two or more. The addition amount of the compound for preventing gelation is usually 0.01% by mass to 1% by mass.

<Method for producing resin composition>
As a method for producing the resin composition, the saturated aldehyde (B) can be uniformly blended in EVOH (A), and the finally obtained resin composition contains 0.01 ppm or more and 100 ppm or less of the saturated aldehyde (B). The method is not particularly limited as long as it is a method. The resin composition includes, for example, a step of copolymerizing ethylene and vinyl ester (hereinafter also referred to as “step (1)”), and a step of saponifying the copolymer obtained by this step (1) (hereinafter referred to as “step (1)”). , Also referred to as “step (2)”).

  The method for containing a specific amount of saturated aldehyde (B) in the resin composition is not particularly limited. For example, a method of adding a specific amount of saturated aldehyde (B) in step (1), specified in step (2). Examples thereof include a method of adding an amount of saturated aldehyde (B), a method of adding a specific amount of saturated aldehyde (B) to EVOH (A) obtained by step (2), and the like.

  However, when the method of adding a specific amount of saturated aldehyde (B) in step (1) or the method of adding a specific amount of saturated aldehyde (B) in step (2) is adopted, the resin composition obtained In order to contain a desired amount of the saturated aldehyde (B), it is necessary to increase the amount of addition in consideration of the amount consumed in the polymerization reaction in step (1) or the saponification reaction in step (2). . However, if the amount of saturated aldehyde (B) is large, these reactions may be inhibited. Moreover, since the amount by which the saturated aldehyde (B) is consumed varies depending on the conditions of the polymerization reaction in the step (1) and the saponification reaction in the step (2), the content of the saturated aldehyde (B) in the resin composition It is difficult to adjust the amount. Therefore, a method of adding a specific amount of the saturated aldehyde (B) to the EVOH (A) obtained by the step (2) after the step (2) is preferable.

  As a method for adding a specific amount of saturated aldehyde (B) to EVOH (A), for example, a method in which saturated aldehyde (B) is previously blended with EVOH (A) and pellets are granulated, an ethylene-vinyl ester copolymer A method of impregnating a saturated aldehyde (B) into a strand to be precipitated after saponification, a method of impregnating a saturated aldehyde (B) after cutting a strand to be precipitated, a saturated aldehyde ( B) adding method, EVOH (A) and saturated aldehyde (B) melt kneading method, EVOH (A) melt into EVOH (A) melt from the middle of the extruder and containing, saturated aldehyde (B) is blended with EVOH (A) at a high concentration and granulated, and the master batch is dry blended with EVOH (A) and melted. How to kneading, and the like.

  Among these, from the viewpoint of uniformly dispersing a small amount of saturated aldehyde (B) in EVOH (A), as a method of adding saturated aldehyde (B), saturated aldehyde (B) is obtained in advance by EVOH (A And a method of granulating pellets by blending with (A). Specifically, the addition of the saturated aldehyde (B) is performed by adding the saturated aldehyde (B) to a solution obtained by dissolving EVOH (A) in a good solvent such as a water / methanol mixed solvent, and using the mixed solution as a nozzle or the like. It is preferable to carry out by extruding into a poor solvent and precipitating and / or solidifying it, and washing and / or drying it. In this case, the resin composition is obtained as pellets in which the saturated aldehyde (B) is uniformly mixed with EVOH (A).

  Examples of the method of adding each component other than the saturated aldehyde (B) to the resin composition include, for example, a method of mixing and melting and kneading the pellet together with the components, and preparing the pellet together with the saturated aldehyde (B). The method of mixing each component, the method of immersing the said pellet in the solution containing each component, etc. are mentioned. In addition, a ribbon blender, a high speed mixer kneader, a mixing roll, an extruder, an intensive mixer, etc. can be used for mixing a pellet and another component.

<Resin molding>
The resin molded body is formed from the resin composition. As this resin molding, a film, a sheet | seat, a container, a pipe, a hose, a fiber, a packaging material etc. are mentioned, for example. The resin molded body is formed by, for example, melt molding, and is formed by performing secondary processing molding as necessary. Examples of the melt molding method include extrusion molding, inflation extrusion, blow molding, melt spinning, injection molding, and injection blow molding. The melt molding temperature is preferably about 150 ° C. to 270 ° C., although it varies depending on the melting point of EVOH (A). Examples of the secondary processing molding include bending, vacuum molding, blow molding, and press molding.

<Multilayer structure>
The multilayer structure includes a layer formed from the resin composition (hereinafter also referred to as “resin composition layer”). The layer structure of the multilayer structure is not particularly limited, but preferably includes a thermoplastic resin layer formed from a thermoplastic resin, and the thermoplastic resin layer is adjacent to the resin composition layer. Is more preferable. The thermoplastic resin layer can also be configured as an adhesive resin layer. This adhesive resin layer adheres the other resin layers to each other, and is a layer having a lower melting point or softening point than the other resin layers.

As the thermoplastic resin forming the thermoplastic resin layer,
High density, medium density or low density polyethylene;
Polyethylene obtained by copolymerizing vinyl acetate, acrylic acid ester, or α-olefins such as butene and hexene;
Ionomer resin;
Polypropylene homopolymer;
Polypropylene copolymerized with α-olefins such as ethylene, butene and hexene;
Polyolefins such as modified polypropylene blended with rubber polymers;
Resins obtained by adding or grafting maleic anhydride to these resins;
Polyester resins are preferred.

  Examples of the thermoplastic resin further include polyamide, polyester, polystyrene, polyvinyl chloride, acrylic resin, polyurethane, polycarbonate, and polyvinyl acetate.

As the layer structure of the multilayer structure, from the viewpoint of moldability and cost, for example, thermoplastic resin layer / resin composition layer / thermoplastic resin layer;
Resin composition layer / thermoplastic resin layer (adhesive resin layer) / thermoplastic resin layer;
Examples include thermoplastic resin layer / thermoplastic resin layer (adhesive resin layer) / resin composition layer / thermoplastic resin layer (adhesive resin layer) / thermoplastic resin layer. When the multilayer structure includes a plurality of thermoplastic resin layers, the plurality of thermoplastic resin layers may be layers made of different resins or layers made of the same resin.

  Among these, a layer configuration of thermoplastic resin layer / resin composition layer / thermoplastic resin layer is preferable, and a layer configuration in which a thermoplastic resin layer made of a polyester resin is laminated on both sides of the resin composition layer is more preferable. .

  The method for obtaining the multilayer structure is not particularly limited. For example, extrusion lamination, dry lamination, extrusion blow molding, coextrusion lamination, coextrusion sheet molding, coextrusion pipe molding, Examples include a coextrusion blow molding method, a co-injection molding method, and a solution coating method. Note that the multilayer structure obtained by such a method may be subjected to secondary processing by vacuum-pressure-air deep drawing, blow molding, or the like after reheating within the range below the melting point of EVOH (A). .

  In addition, the scrap generated at the time of forming the multilayer structure may be reused by blending with the thermoplastic resin layer or may be used separately.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by a following example.

(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 Lambda500” manufactured by JEOL Ltd.), DMSO-d ₆ as a measurement solvent, and ¹ H-NMR Asked.

(3) Quantification of carboxylic acid and carboxylate ion The dried EVOH pellets were pulverized by freeze pulverization. The obtained pulverized EVOH was divided by a sieve having a nominal size of 1 mm (conforming to standard fluid standard JIS Z8801-3). 10 g of EVOH powder and 50 mL of ion exchanged water that passed through the sieve were put into a 100 mL Erlenmeyer flask with a stopper, and a cooling condenser was attached, followed by stirring at 95 ° C. for 10 hours. 2 mL of the obtained solution was diluted with 8 mL of ion exchange water. The amount of the carboxylic acid and the carboxylate ion was calculated by quantifying the amount of the carboxylate ion of this diluted solution according to the following measurement conditions using ion chromatography “ICS-1500” manufactured by Yokogawa Electric Corporation. A calibration curve prepared using monocarboxylic acid or polyvalent carboxylic acid was used for quantification.

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

(4) Determination of metal ions 0.5 g of dry EVOH pellets were charged into a Teflon (registered trademark) pressure vessel made by Actac, and 5 mL of nitric acid for precision analysis from Wako Pure Chemical Industries, Ltd. was further added. After standing for 30 minutes, the container is covered with a cap lip with a rupture disk, treated at 150 ° C for 10 minutes and then at 180 ° C for 10 minutes with Actac's microwave high-speed decomposition system "Speedwave MWS-2", and dried EVOH The pellet was broken down. When the decomposition of the dry EVOH pellets 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.

  By using the ICP emission spectroscopic analyzer “Optima 4300 DV” of PerkinElmer Japan, the obtained decomposition product solution is quantitatively analyzed at each of the following observation wavelengths, so that metal ions, phosphate compounds and boron compounds can be obtained. The amount 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 boric acid 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 (A)>
[Synthesis Example 1]
Polymerization was carried out under the following conditions using a 250 L pressurized reaction tank to synthesize an ethylene-vinyl acetate copolymer.

(Preparation amount)
Vinyl acetate 83.0kg
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 conditions)
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 pellets were drained with a centrifuge, and the operation of adding a large amount of water and draining was repeated.

[Synthesis Example 2]
Pellets were obtained by polymerization, saponification, pelletization and washing in the same manner as in Synthesis Example 1 except that propanal was supplied so that the propanal concentration was 0.5 ppm during the polymerization.

<Preparation of resin composition>
[Examples 1 to 9, 12 to 18, 21 and Comparative Example 2]
20 kg of pellets obtained by draining in Synthesis Example 1 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. A saturated aldehyde (B) and a conjugated polyene compound were added to the resulting solution, and the mixture was further stirred for 1 hour to completely dissolve the saturated aldehyde (B) and the conjugated polyene compound, thereby obtaining a resin composition solution. This resin composition 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 resin composition chip. The obtained porous resin composition chip was washed with an aqueous acetic acid solution and ion-exchanged water, and then immersed in an aqueous solution containing acetic acid, sodium acetate, potassium dihydrogen phosphate and boric acid. The aqueous solution for immersion treatment and the resin composition chip were separated and drained, and then placed in a hot air dryer, dried at 80 ° C. for 4 hours, and further dried at 100 ° C. for 16 hours to obtain a resin composition ( Dry resin composition pellets) were obtained. The content of each component in the obtained resin composition was quantified using the above quantification method. The resin composition was prepared so that the content of each component was as shown in Table 1 by adjusting the amount of saturated aldehyde (B) added and the concentration of each component of the aqueous solution for immersion treatment.

[Example 10]
Resin composition pellets were prepared in the same manner as in Example 1 except that myrcene was used in place of sorbic acid as the conjugated polyene compound.

[Example 11]
Resin composition pellets were prepared in the same manner as in Example 1 except that potassium sorbate was used in place of sorbic acid as the conjugated polyene compound.

[Example 19]
Resin composition pellets were prepared in the same manner as in Example 1 except that butanal was used as the saturated aldehyde instead of propanal.
[Example 20]
Resin composition pellets were prepared in the same manner as in Example 1 except that hexanal was used in place of propanal as a saturated aldehyde.

[Comparative Examples 1, 3, 4]
20 kg of the pellets obtained in Synthesis Example 2 above 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. To the obtained solution, sorbic acid was added as a conjugated polyene compound, and the mixture was further stirred for 1 hour to completely dissolve sorbic acid to obtain a resin composition solution. This resin composition 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 resin composition chip. The obtained porous resin composition chip was washed with an aqueous acetic acid solution and ion-exchanged water, and then immersed in an aqueous solution containing acetic acid, sodium acetate, potassium dihydrogen phosphate and boric acid. The aqueous solution for immersion treatment and the resin composition chip are separated and drained, and then placed in a hot air dryer, dried at 80 ° C. for 4 hours, and further dried at 100 ° C. for 16 hours to obtain a resin composition (dried Resin composition pellets) were obtained. The content of each component in the obtained resin composition was quantified using the above quantification method. In addition, the resin composition of Comparative Examples 1, 3, and 4 was prepared so that content of each component might become as the description of Table 1 by adjusting the density | concentration of each component of the aqueous solution for immersion treatment. Here, the saturated aldehyde (B) was less than the detection lower limit.

[Comparative Example 5]
Resin composition pellets were prepared in the same manner as in Example 1 except that no saturated aldehyde was used.

<Evaluation of resin composition>
About the resin composition of Examples 1-21 and Comparative Examples 1-5, content of each component, the odor at the time of shaping | molding, long run property, film external appearance, solution external appearance, and motor torque fluctuation | variation were evaluated in accordance with the following method. The evaluation results are also shown in Table 1.

[Saturated aldehyde content]
To 200 mg of 50 mass% 2,4-dinitrophenylhydrazine (DNPH) solution, add 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) 50 mL, acetic acid 11.5 mL and ion-exchanged water 8 mL. A DNPH adjustment solution was prepared. Thereafter, 1 g of the dried resin composition pellets was added to 20 mL of the DNPH adjustment solution and dissolved by stirring at 35 ° C. for 1 hour. Acetonitrile was added to this solution to precipitate EVOH (A), and the solution was filtered and concentrated to obtain an extracted sample. The amount of saturated aldehyde (B) was quantified by quantitatively analyzing the extracted sample with high performance liquid chromatography. For quantification, a calibration curve prepared using a standard obtained by reacting each saturated aldehyde (B) with a DNPH preparation solution was used.

Column: TSKgel ODS-80Ts (Tosoh Corporation)
Mobile phase: water / acetonitrile = 52: 48 (volume ratio)
Detector: PDA (360 nm), TOF-MS

[Content of Conjugated Polyene Compound]
The dried resin composition pellets are pulverized by freeze pulverization, and 10 g of pulverized material obtained by removing coarse particles by a sieve having a nominal size of 0.150 mm (100 mesh) (conforming to JIS standard Z8801-1-3) is put into a Soxhlet extractor. Filled 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.

[Odor during molding]
20 g of sample pellets of the resin composition were placed in 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 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

[Long run]
Using a single-screw extruder (“D2020” manufactured by Toyo Seiki Seisakusho; D (mm) = 20, L / D = 20, compression ratio = 2.0, screw: full flight), each dry resin composition A single-layer film having a thickness of 20 μm was prepared from the product pellets.

(Test conditions)
Extrusion temperature: 220 ° C
Screw rotation speed: 40rpm
Dice width: 30cm
Take-up roll temperature: 80 ° C
Take-up roll speed: 3.1 m / min

  A single layer film was produced by continuous operation under the above conditions, and the number of defects per 17 cm film length was counted for each film produced 8 hours and 15 hours after the start of operation. The number of defects was counted using a film defect inspection apparatus ("AI-10" from Frontier System). In addition, the detection camera in the said apparatus was installed so that the lens position might become a distance of 195 mm from the film surface. The long run property of each resin composition was evaluated according to the following criteria.

A (good): the number of defects is less than 50 B (slightly good): the number of defects is 50 or more and less than 200 C (defect): the number of defects is 200 or more

[Coloring roll ends]
Each film produced 8 hours and 15 hours after the start of operation in the same manner as the evaluation of the long run property was made into a roll, and coloring of the end of this roll was confirmed. The color of the roll end of each resin composition was evaluated according to the following criteria.

A (good): no coloring is observed at the roll end B (slightly good): coloring is observed at the roll end, but there is no problem as a product C (defect): clear coloring is observed at the roll end

[Film appearance]
About the film produced 15 hours after the operation start, the external appearance was confirmed visually. The film appearance was evaluated for each of streaks and coloring according to the following criteria.

(Evaluation criteria for streak)
A (good): no streaks were observed B (slightly good): streaks were confirmed C (poor): many streaks were confirmed

(Evaluation criteria for coloring)
A (good): colorless B (slightly good): yellowing C (poor): markedly yellowing

[Solution appearance]
10 g of the pellets obtained by heat-treating the dried resin composition pellets at 120 ° C. for 15 hours in air are placed in a 300 mL Erlenmeyer flask, 100 mL of a water / propanol mixed solution (mass ratio: water / propanol = 45/55) is added, and 3 ° C. is added at 75 ° C. Stir for hours and visually check the solution. The solution appearance was evaluated for each of transparency and coloring of the solution according to the following criteria.

(Transparency evaluation criteria)
A (good): Transparent (no floating matter that can be visually confirmed)
B (slightly good): Slightly cloudy (there is a suspended matter that can be visually confirmed)
C (defect): cloudiness (there is suspended matter)

(Solution coloring criteria)
A (good): colorless B (slightly good): slightly colored C (poor): markedly colored

[Motor torque fluctuation]
Kneaded 60 g of dry resin composition pellets at Labo Plast Mill (Toyo Seiki Seisakusho "20R200"; biaxial different direction) at 100 rpm and 260 ° C until the torque value after 5 minutes from the start of kneading becomes 1.5 times It was done by measuring the required time. The motor torque fluctuation was evaluated according to the following criteria. The viscosity of the resin composition in the heated state is a factor affecting the long run property during secondary processing.

A (good): 60 minutes or more B (slightly good): 40 minutes or more and less than 60 minutes C (poor): less than 40 minutes

  As shown in Table 1, the resin compositions of Examples 1 to 21 were able to form films with excellent aesthetics in which the odor during molding was suppressed and the occurrence of streak and coloration of the film hardly occurred. Moreover, it turned out that the resin composition of Examples 1-21 is excellent in the long run property at the time of melt molding by the motor torque fluctuation | variation at the time of heating and the generation | occurrence | production number of the defect at the time of film formation being suppressed.

<Manufacture of multilayer structure>
[Example 22]
Using a seven-layer coextrusion cast film forming facility equipped with the following four types of extruders, a coextrusion film forming test of a multilayer film as a multilayer structure was performed.

Extruder for outer layer polyolefin (1): single screw, screw diameter 65 mm, L / D = 22
Extruder for polyolefin (2): single screw, screw diameter 40mm, L / D = 26
Adhesive resin extruder (3): single screw, screw diameter 40 mm, L / D = 22
EVOH extruder (4): single screw, screw diameter 40 mm, L / D = 26

  Polypropylene (hereinafter referred to as “PP”) is supplied to the extruder (1) and the extruder (2), and a maleic anhydride-modified polypropylene adhesive resin (“ADMER QF-” manufactured by Mitsui Chemicals, Inc.) is supplied to the extruder (3). 500 ”), the resin composition obtained in Example 1 was supplied to the extruder (4), and co-extrusion film formation was performed to obtain a multilayer film having a seven-layer structure with a total thickness of 100 μm. The extrusion temperature is 200-250 ° C. for the extruder (1), 200-250 ° C. for the extruder (2), 160-250 ° C. for the extruder (3), and 170-250 for the extruder (4). The temperature was set to 250 ° C. for the feed block and the die. The configuration and thickness of the multilayer film were PP / PP / adhesive resin / resin composition / adhesive resin / PP / PP = 30 μm / 15 μm / 2.5 μm / 5 μm / 2.5 μm / 15 μm / 30 μm.

  The multilayer film 10 hours after the start of film formation was sampled and the appearance was observed. As a result, the appearance defect due to the aggregation of EVOH and the flow mark due to the flow abnormality were hardly recognized, and a multilayer film having no practical problem was obtained.

[Comparative Example 6]
A multilayer film was prepared in the same manner as in Example 22 except that the resin composition of Comparative Example 5 was used instead of the resin composition of Example 1, and the multilayer film 10 hours after the start of film formation was sampled. When the appearance of this multilayer film was observed, many appearance marks due to EVOH aggregation and many flow marks due to flow abnormalities were observed.

Since the resin composition of this invention can suppress generation | occurrence | production and the coloring of the defect at the time of melt molding, it can provide the molded article which is excellent in external appearance property. Further, the resin composition is excellent in long-run property because defects and odor are hardly generated even after long-time melt molding. Therefore, the said resin composition is shape | molded in a container, a film, a sheet | seat, etc., The molded object can be used suitably as a multilayer structure and various packaging materials.

Claims (10)

Containing an ethylene-vinyl alcohol copolymer (A) and a saturated aldehyde (B),
The content of the ethylene-vinyl alcohol copolymer (A) is 95% by mass or more,
Ri 100ppm der less content of 0.3 ppm or more of the above unsaturated aldehyde (B),
A resin composition having an alkali metal content of 1,000 ppm or less .   The resin composition according to claim 1, wherein the saturated aldehyde (B) has 3 to 8 carbon atoms.   The resin composition according to claim 2, wherein the saturated aldehyde (B) is at least one selected from the group consisting of propanal, butanal and hexanal. Further containing a boron compound,
The resin composition according to claim 1, wherein the content of the boron compound is 100 ppm or more and 5,000 ppm or less. Further containing a conjugated polyene compound,
The resin composition according to any one of claims 1 to 4, wherein the content of the conjugated polyene compound is 0.01 ppm or more and 1,000 ppm or less.   The resin composition according to claim 5, wherein the conjugated polyene compound is at least one of sorbic acid and sorbate. Further containing at least one of acetic acid and acetate,
The resin composition according to any one of claims 1 to 6, wherein the total content of the acetic acid and the acetate is 50 ppm or more and 1,000 ppm or less. Further containing a phosphorus compound;
The resin composition according to any one of claims 1 to 7, wherein a content of the phosphorus compound is 1 ppm or more and 200 ppm or less.   The resin molding formed from the resin composition of any one of Claims 1-8. The multilayer structure containing the layer formed from the resin composition of any one of Claims 1-8.