Resin composition and layered body

Abstract

The purpose of the present invention is to provide a resin composition that is less colored and contains a polyolefin-based resin and a polyvinyl alcohol-based resin. The present invention relates to a resin composition that contains a polyolefin-based resin (A), a polyvinyl alcohol-based resin (B), and acetic acid (C), wherein the content of the acetic acid (C) with respect to the whole amount is 10 ppm by mass or more but less than 60 ppm by mass.

Description

Resin composition and laminate

[0001] The present invention relates to resin compositions and laminates.

[0002] Conventionally, resin films made of polyamide resins, polyester resins, polyolefin resins, etc., have been used as packaging materials. For packaging materials of items whose quality deteriorates due to oxygen, such as food and beverages, pharmaceuticals, and chemicals, single resin films of the above-mentioned resins do not provide sufficient oxygen gas barrier properties. Therefore, laminates that combine materials with oxygen gas barrier properties by coating, laminating, co-extrusion molding, etc., are widely used.

[0003] As such a laminate, for example, a multilayer film produced by co-extrusion molding of a polyvinyl alcohol-based resin (hereinafter also referred to as "PVA-based resin") and a polyolefin-based resin is used (Patent Document 1). On the other hand, it is also known that a resin composition is used in which the polyvinyl alcohol-based resin and polyolefin-based resin constituting each layer of such a laminate are mixed (Patent Document 2).

[0004] Japanese Patent Publication No. 4883281 Japanese Patent Publication No. 2007-126586

[0005] As described above, multilayer films, which are constructed by laminating layers containing different resins, are useful because they can exhibit the properties of the resins contained in each layer. In recent years, instead of multilayer films in which different resins are contained in each layer, the production of films obtained from resin compositions made by mixing different resins has been investigated.

[0006] For example, when a PVA resin is added to a polyolefin resin, a resin composition can be obtained that possesses the properties of the polyolefin resin as well as the surfactant properties, mechanical properties, and gas barrier properties of the PVA resin. However, according to the inventors' studies, the obtained resin composition may exhibit discoloration derived from the PVA resin, resulting in an increase in the yellow index (hereinafter also referred to as "YI"), which leads to a problem of reduced functionality in the film obtained from the resin composition.

[0007] Therefore, the present invention aims to provide a resin composition that exhibits minimal coloration and contains polyolefin resins and polyvinyl alcohol resins.

[0008] In view of these circumstances, the inventors conducted extensive research and, as a result, discovered that a resin composition containing a polyolefin resin and a polyvinyl alcohol resin can be made less discolored by further adding a predetermined amount of acetic acid, thus completing the present invention.

[0009] In other words, the present invention encompasses the following embodiments.

[0010] One aspect of the present invention relates to a resin composition containing a polyolefin resin (A), a polyvinyl alcohol resin (B), and acetic acid (C), wherein the content of acetic acid (C) relative to the total amount is 10 ppm by mass or more and less than 60 ppm by mass.

[0011] Aspect 2 of the present invention relates to a resin composition of Aspect 1, wherein the resin composition comprises at least one selected from the group consisting of polyethylene and polypropylene as the polyolefin resin (A).

[0012] Aspect 3 of the present invention relates to a resin composition of aspect 1 or 2, wherein the resin composition includes a modified polyvinyl alcohol resin as the polyvinyl alcohol resin (B).

[0013] Aspect 4 of the present invention relates to a resin composition of Aspect 3, wherein the amount of modification of the modified polyvinyl alcohol-based resin is 1 to 20 mol% with respect to the vinyl alcohol units in the polyvinyl alcohol main chain.

[0014] Aspect 5 of the present invention relates to a resin composition according to aspect 3 or 4, wherein the modified polyvinyl alcohol resin is a modified polyvinyl alcohol resin containing structural units with primary hydroxyl groups in the side chains.

[0015] Aspect 6 of the present invention relates to a resin composition in which, in any one of the resin compositions of aspects 1 to 5, the content of acetic acid (C) is 58 ppm by mass or less relative to the total amount of the resin composition.

[0016] Aspect 7 of the present invention relates to the resin composition according to any one of Aspects 1 to 6, wherein the content of acetic acid (C) is 55 mass ppm or less relative to the total amount of the resin composition.

[0017] Aspect 8 of the present invention relates to the resin composition according to any one of Aspects 1 to 7, which contains 70 to 99 mass% of a polyolefin-based resin (A) relative to the total amount of the resin composition.

[0018] Aspect 9 of the present invention relates to the resin composition according to any one of Aspects 1 to 8, which contains 0.1 to 15 mass% of a polyvinyl alcohol-based resin (B) relative to the total amount of the resin composition.

[0019] Aspect 10 of the present invention relates to the resin composition according to any one of Aspects 1 to 9, which contains a total of 60 to 100 mass% of the polyolefin-based resin (A), the polyvinyl alcohol-based resin (B) and acetic acid (C) relative to the total amount of the resin composition.

[0020] Aspect 11 of the present invention relates to the resin composition according to any one of Aspects 1 to 10, which further contains an acid-modified polyolefin-based resin (D).

[0021] Aspect 12 of the present invention relates to the resin composition according to any one of Aspects 1 to 11, which contains 0.5 to 15 mass% of the acid-modified polyolefin-based resin (D) relative to the total amount of the resin composition.

[0022] Aspect 13 of the present invention relates to a laminate having at least one layer comprising the resin composition according to any one of Aspects 1 to 12.

[0023] The present invention can provide a resin composition that has little discoloration and contains a polyolefin-based resin and a polyvinyl alcohol-based resin.

[0024] The resin compositions according to this embodiment will be described in detail below, but these are merely examples of desirable embodiments and are not limiting. In this specification, when expressed as "X to Y" (where X and Y are any numbers), unless otherwise specified, it means "X or more and Y or less," and also includes the meaning of "preferably greater than X" or "preferably less than Y." Also, when expressed as "X or more" (where X is any number) or "Y or less" (where Y is any number), it also includes the meaning of "preferably greater than X" or "preferably less than Y." Furthermore, for numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in one stage can be arbitrarily combined with the upper or lower limit of a numerical range in another stage. Also, in numerical ranges described in this specification, the upper or lower limit of that numerical range can be replaced with the values ​​shown in the examples. In this specification, unless otherwise specified, "parts" refers to "parts by mass."

[0025] The resin composition according to this embodiment contains a polyolefin resin (A), a polyvinyl alcohol resin (B), and acetic acid (C), wherein the content of acetic acid (C) relative to the total amount is 10 ppm by mass or more and less than 60 ppm by mass.

[0026] The reason why the resin composition according to this embodiment contains a predetermined amount of acetic acid (C) results in less discoloration is not clear, but the following reasons are possible.

[0027] Because polyvinyl alcohol-based resins are hydrophilic, they easily absorb moisture unless they are packaged in completely moisture-proof packaging. When this moisture is heated and evaporates during extrusion molding, the latent heat of vaporization suppresses the rise in resin temperature due to shear heating, thus reducing the thermal history. However, since the boiling point of water is 100°C, if the resin temperature exceeds 100°C during mixing, the moisture will completely evaporate, and the resin temperature will rise. If acetic acid is added to the resin composition, since the boiling point of acetic acid is higher than that of water, the acetic acid remains in the resin even after the resin temperature exceeds 100°C, and the rise in resin temperature can be suppressed by the latent heat of vaporization. As a result, the thermal history of the resin composition is reduced, and discoloration is thought to be reduced.

[0028] As described later, the resin composition according to this embodiment may further contain an acid-modified polyolefin resin (D). The preferred mass ratio of the polyolefin resin (A), polyvinyl alcohol resin (B), and acid-modified polyolefin resin (D) in the resin composition is 70 to 99.9:15 to 0.1:15 to 0, and more preferably 80 to 99.5:10 to 0.5:10 to 1. This ratio has the advantage of resulting in less discoloration.

[0029] In the resin composition, the polyolefin resin (A), the polyvinyl alcohol resin (B), and the acid-modified polyolefin resin (D) are each contained as different resins.

[0030] [Polyolefin Resins (A)] Examples of polyolefin resins (A) include polyethylene such as linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), very low-density polyethylene (VLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE); ethylene-vinyl acetate copolymer (EVA); ionomers; ethylene-propylene (block or random) copolymer; ethylene-acrylic acid copolymer; ethylene-methacrylic acid copolymer; polypropylene; propylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymer; polybutene; polypentene; polymethylpentene; and other olefins, either alone or in copolymer form, or blends thereof. Note that acid-modified polyolefin resins (D) are not included in polyolefin resins (A).

[0031] In particular, from the viewpoint of economic efficiency and mechanical properties, polyethylene or polypropylene is preferred as the polyolefin resin (A), and polypropylene is especially preferred. That is, the polyolefin resin (A) preferably contains at least one selected from the group consisting of polyethylene and polypropylene, and it is especially preferred to contain polypropylene.

[0032] As for polyethylene, the density is 0.86 to 0.97 g / cm³. ３A linear low-density polyethylene composed of an ethylene / α-olefin copolymer is preferably used. The density is 0.86 g / cm ３ or higher, which is preferred because various mechanical properties of the laminated packaging material become favorable and blocking is less likely to occur. In addition, the density of 0.97 g / cm ３ or lower is preferred because flex fatigue resistance, vibration fatigue resistance and the like become favorable. The density referred to herein is a value measured at 20°C in accordance with JIS K7122:1999, and the ethylene / α-olefin copolymer refers to a copolymer of ethylene and an α-olefin usually having 18 or less carbon atoms, such as butene-1, pentene-1, 4-methylpentene-1, hexene-1, and octene-1. Among these, an ethylene / α-olefin copolymer using an olefin having 4 to 8 carbon atoms is suitably used.

[0033] As the above linear low-density polyethylene, an ethylene / α-olefin copolymer produced in the presence of a single-site catalyst is further preferred. The single-site catalyst is a catalyst characterized by uniform (single-site) active sites, different from conventional multi-site catalysts such as Ziegler catalysts and Phillips catalysts which have non-uniform active sites, and typical examples thereof include metallocene catalysts and the like. Specific commercial names of single-site catalysts include "Kernel ＴＭ " (manufactured by Nippon Polychem Co., Ltd.), "Evolue ＴＭ " (manufactured by Mitsui Chemicals, Inc.), "Exact ＴＭ " (manufactured by ExxonMobil Chemical Company), "Affinity ＴＭ " (manufactured by The Dow Chemical Company), and the like.

[0034] As the polypropylene, a polypropylene having a density of 0.87 to 0.93 g / cm ３ is preferably used. A density of 0.87 g / cm ３ or higher is preferred because various mechanical properties of the laminated packaging material become favorable and blocking is less likely to occur. In addition, a density of 0.93 g / cm ３The following conditions are preferable because they result in good resistance to flexural fatigue and vibration fatigue. The density referred to here is the value measured at 20°C according to JIS K7122:1999. In particular, 0.89 to 0.91 g / cm³ is preferable. ３ Polypropylene is preferably used.

[0035] The melting point of the polyolefin resin (A) is preferably 100 to 190°C, more preferably 100 to 180°C, and particularly preferably 100 to 170°C. This melting point was measured by differential scanning calorimetry (hereinafter abbreviated as "DSC") in accordance with JIS K7121:2012.

[0036] The melt flow rate (MFR) of the polyolefin resin (A) (according to JIS K7210:2014: 230°C, load 21.2N) is preferably 0.1 to 50 g / 10 min, and more preferably 0.5 to 30 g / 10 min.

[0037] There is no particular lower limit to the content of polyolefin resin (A) in the resin composition, but from the viewpoint of moldability, it is preferable that it be 70% by mass or more, more preferably 80% by mass or more, and particularly preferable 85% by mass or more, relative to the total amount of the resin composition. Furthermore, there is no particular upper limit to the content of polyolefin resin (A) in the resin composition, but from the viewpoint of functionality, it is preferable that it be 99% by mass or less, more preferably 98% by mass or less, and particularly preferable 97% by mass or less, relative to the total amount of the resin composition. In one embodiment, the resin composition may contain 70 to 99% by mass of polyolefin resin (A) relative to the total amount, more preferably 80 to 98% by mass, and even more preferably 85 to 97% by mass.

[0038] [Polyvinyl alcohol-based resin (PVA-based resin) (B)] Generally, polyvinyl alcohol-based resins are resins obtained by saponifying a homopolymer of vinyl ester monomers, or a copolymer of vinyl ester monomers and other monomers (hereinafter, these are also referred to as "vinyl ester polymers") using an alkaline catalyst or the like. However, the polyvinyl alcohol-based resin (B) in this embodiment does not include so-called polyethylene vinyl alcohol-based resins in which the content of ethylene units relative to the total monomer is 20 mol% or more. Therefore, in polyvinyl alcohol-based resin (B), the total amount of vinyl ester monomers and other monomers other than ethylene is 80 mol% or more relative to the total monomer.

[0039] From the viewpoint of extrusion moldability, the polyvinyl alcohol-based resin (B) preferably contains a modified polyvinyl alcohol-based resin, and more preferably consists of a modified polyvinyl alcohol-based resin. A modified polyvinyl alcohol-based resin is a resin in which a modifying group is introduced by copolymerization or post-reaction to a resin mainly composed of vinyl alcohol structural units obtained by saponifying a polyvinyl ester resin obtained by polymerizing a vinyl ester compound. The modified polyvinyl alcohol-based resin consists of vinyl alcohol structural units corresponding to the degree of saponification, vinyl ester structural units that remain unsaponified, as well as unsaturated monomer structural units by copolymerization or structural units by post-reaction.

[0040] Examples of the vinyl ester compounds mentioned above include vinyl formate, vinyl acetate, vinyl trifluoroacetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurylate, vinyl versaticate, vinyl palmitate, and vinyl stearate, but vinyl acetate is preferred. The vinyl ester compounds may be used alone or in combination of two or more.

[0041] Copolymerized modified polyvinyl alcohol resins (copolymerized modified polyvinyl alcohol resins) include vinyl ester monomers and unsaturated monomers copolymerizable with vinyl ester monomers, such as olefins like ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadecene; unsaturated acids like acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, their salts, monoesters, or dialkyl esters; nitriles like acrylonitrile and methacrylonitrile; amides like acrylamide and methacrylamide; olefin sulfonic acids like ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid or their salts; alkyl vinyl ethers; N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, N-vinylpyrrolidone; vinyl chloride; vinylidene chloride; and polyoxyethylene. Examples include those obtained by copolymerization with polyoxyalkylene (meth)allyl ethers such as (meth)allyl ether and polyoxypropylene (meth)allyl ether, polyoxyalkylene (meth)acrylates such as polyoxyethylene (meth)acrylate and polyoxypropylene (meth)acrylate, polyoxyalkylene (meth)acrylamides such as polyoxyethylene (meth)acrylamide and polyoxypropylene (methacrylamide), polyoxyethylene (1-(meth)acrylamide-1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, hydroxyl group-containing α-olefins such as 3-buten-1-ol, 4-penten-1-ol, and 5-hexen-1-ol, and derivatives such as their acylated products.

[0042] The amount of modification in the modified polyvinyl alcohol resin is preferably 1 to 20 mol%, more preferably 2 to 10 mol%, and particularly preferably 3 to 8 mol%, relative to the vinyl alcohol units in the polyvinyl alcohol main chain. A modification amount of 1 mol% or more has the advantage of good extrusion moldability. Furthermore, a modification amount of 20 mol% or less has the advantage of reduced metal adhesion, improved flowability during melt molding, and reduced thermal degradation due to stagnation, etc.

[0043] Furthermore, examples of post-modified polyvinyl alcohol resins (post-modified polyvinyl alcohol resins) include those having an acetoacetyl group obtained by reaction with diketene, those having a polyalkylene oxide group obtained by reaction with ethylene oxide, those having a hydroxyalkyl group obtained by reaction with epoxy compounds, etc., or aldehyde compounds having various functional groups, obtained by reacting them with polyvinyl alcohol resins through esterification, acetalization, urethaneization, etherification, grafting, phosphate esterification, oxyalkyleneization, etc.

[0044] Furthermore, as the modified polyvinyl alcohol resin, a modified polyvinyl alcohol resin containing a structural unit with a primary hydroxyl group in its side chain is preferred, and among these, a modified polyvinyl alcohol resin containing a 1,2-diol structure is preferred, and a modified polyvinyl alcohol resin having a 1,2-diol structural unit represented by the following general formula (1) is even more preferred. In general formula (1), R １ , R ２ , and R ３ Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, X represents a single bond or a bonded chain, and R ４ , R ５ , and R ６ Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0045]

[0046] In particular, R in the 1,2-diol structural unit represented by general formula (1) １ ~R ３ , and R ４~R ６ Most preferably, the material consists entirely of hydrogen atoms and X is a single bond, and a modified polyvinyl alcohol resin having a structural unit represented by the following general formula (1') is preferably used.

[0047]

[0048] Furthermore, R in the structural unit represented by the general formula (1) １ ~R ３ , and R ４ ~R ６ The alkyl group may be a C1-C4 alkyl group in an amount that does not significantly impair the resin properties. Examples of C1-C4 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl groups. Such C1-C4 alkyl groups may optionally have functional groups such as halogen atoms, hydroxyl groups, ester groups, carboxylic acid groups, and sulfonic acid groups.

[0049] Furthermore, in the 1,2-diol structural unit represented by general formula (1), a single bond is most preferable for X in terms of thermal stability and stability under high temperature and acidic conditions, but a bonding chain may also be used as long as it does not hinder the effects of the present invention. Such bonding chains may include hydrocarbons such as alkylene, alkenylene, alkynylene, phenylene, and naphthylene (these hydrocarbons may be substituted with halogen atoms such as fluorine, chlorine, or bromine atoms), as well as -O-, -(CH ２ O) ｍ -, - (OCH ２ ) ｍ -, - (CH ２ O) ｍ CH ２ -, -CO-, -COCO-, -CO(CH ２ ) ｍ CO-, -CO(C ６ H ４ )CO-, -S-, -CS-, -SO-, -SO ２ -, -NR-, -CONR-, -NRCO-, -CSNR-, -NRCS-, -NRNR-, -HPO ４ -, -Si (OR) ２ -, -OSi(OR) ２-, -OSi(OR) ２ O-, -Ti (OR) ２ -, -OTi(OR) ２ -, -OTi(OR) ２ Examples include O-, -Al(OR)-, -OAl(OR)-, -OAl(OR)O-, etc. (where R is an arbitrary substituent, preferably a hydrogen atom or an alkyl group, and m is a natural number). Among these, alkylene groups with 6 or fewer carbon atoms, especially methylene groups, or -CH are preferred in terms of stability during production or use. ２ OCH ２ - is preferable.

[0050] Examples of modified polyvinyl alcohol resins containing a 1,2-diol structure include Nichigo G-Polymer. ＴＭ Examples include (manufactured by Mitsubishi Chemical Corporation), etc. Nichigo G-Polymer ＴＭ For example, this can be manufactured by the method described in paragraphs

[0026] to

[0034] of Japanese Patent Publication No. 2015-143356.

[0051] The content of 1,2-diol structural units in a modified polyvinyl alcohol resin containing a 1,2-diol structure is the same as that of a modified polyvinyl alcohol resin that has been completely saponified. １ It can be determined from the 1H-NMR spectrum (solvent: DMSO-d6, internal standard: tetramethylsilane), and specifically, it can be calculated from the peak areas derived from the hydroxyl protons, methine protons, and methylene protons in the 1,2-diol unit, the methylene proton of the main chain, and the protons of the hydroxyl group linked to the main chain.

[0052] The amount of modification in the modified polyvinyl alcohol resin containing the 1,2-diol structure is preferably 1 to 20 mol%, more preferably 2 to 10 mol%, and particularly preferably 3 to 8 mol%. A modification amount of 1 mol% or more has the advantage of good extrusion moldability. Furthermore, a modification amount of 20 mol% or less has the advantage of reduced metal adhesion, improved flowability during melt molding, and reduced thermal degradation due to stagnation, etc.

[0053] As a copolymerization method for the vinyl ester compound and an unsaturated monomer copolymerizable with the vinyl ester compound, any known polymerization method such as solution polymerization, emulsion polymerization, or suspension polymerization can be used. However, it is usually carried out by solution polymerization using an alcohol such as methanol, ethanol, or isopropyl alcohol as the solvent.

[0054] As the polymerization catalyst, known polymerization catalysts such as azo catalysts like azobisisobutyronitrile, and peroxide catalysts like acetyl peroxide, benzoyl peroxide, and lauroyl peroxide can be appropriately selected depending on the polymerization method. The polymerization reaction temperature is selected from a range of 50°C to approximately the boiling point.

[0055] Saponification can be carried out by known methods, and is usually performed by dissolving the obtained copolymer in an alcohol in the presence of a saponification catalyst. Examples of alcohols include methanol, ethanol, and butanol. The concentration of the copolymer in the alcohol is selected from a range of 20 to 50% by mass from the viewpoint of solubility.

[0056] As the saponification catalyst, alkali catalysts such as alkali metal hydroxides or alkoxides, including sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, and potassium methylate, can be used, and acid catalysts can also be used. The amount of saponification catalyst used is preferably 1 to 100 mmol equivalents relative to the vinyl ester compound.

[0057] The average degree of saponification of the polyvinyl alcohol-based resin (B) contained in the resin composition according to this embodiment is preferably 70 to 100 mol%, more preferably 90 to 99.9 mol%, and particularly preferably 98 to 99.8 mol%. An average degree of saponification of 70 mol% or more is preferable because it makes the polyvinyl alcohol-based resin less susceptible to thermal decomposition. The degree of saponification of the polyvinyl alcohol-based resin is a value measured in accordance with JIS K6726:1994.

[0058] The melting point of the polyvinyl alcohol-based resin (B) is preferably 150 to 230°C, more preferably 160 to 225°C, and particularly preferably 170 to 220°C. This melting point was measured by DSC in accordance with JIS K7121:2012.

[0059] There is no particular lower limit to the content of polyvinyl alcohol-based resin (B) in the resin composition, but from the viewpoint of functionality, it is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more, relative to the total amount of the resin composition. Furthermore, there is no particular upper limit to the content of polyvinyl alcohol-based resin (B) in the resin composition, but from the viewpoint of moldability, it is preferably 15% by mass or less, more preferably 12.5% ​​by mass or less, and particularly preferably 10% by mass or less, relative to the total amount of the resin composition. In one embodiment, the resin composition may contain 0.1 to 15% by mass of polyvinyl alcohol-based resin (B) relative to the total amount, more preferably 0.3 to 12.5% ​​by mass, and even more preferably 0.5 to 10% by mass.

[0060] [Acetic Acid (C)] The content of acetic acid (C) in the resin composition is 10 ppm by mass or more, preferably 12 ppm by mass or more, more preferably 15 ppm by mass or more, and particularly preferably 18 ppm by mass or more, based on the total amount of the resin composition.

[0061] The upper limit of the acetic acid (C) content in the resin composition is less than 60 ppm by mass, preferably 58 ppm by mass or less, more preferably 55 ppm by mass or less, and even more preferably less than 55 ppm by mass, based on the total amount of the resin composition, from the viewpoint of preventing reaction with the hydroxyl groups of the polyvinyl alcohol-based resin (B) when the resin composition is melt-kneaded and effectively suppressing the rise in resin temperature due to the latent heat of vaporization. In one embodiment, the acetic acid (C) content in the resin composition can be 10 ppm by mass or more and less than 60 ppm by mass, 12 ppm by mass or more and less than 60 ppm by mass, 15 ppm by mass or more and less than 60 ppm by mass, 18 ppm by mass or more and less than 60 ppm by mass, 12 to 58 ppm by mass, 15 to 55 ppm by mass, 18 ppm by mass or more and less than 55 ppm by mass, etc., based on the total amount of the resin composition.

[0062] The content of acetic acid (C) in the resin composition can be adjusted by the amount of acetic acid added.

[0063] Note that the acetic acid (C) content in the resin composition may be lower than the content calculated from the amount added. This is because some of the acetic acid (C) volatilizes during melt mixing and is released through the reduced pressure section (vent). In such cases, the amount of acetic acid (C) added should be increased or decreased so that the acetic acid (C) content in the resin composition falls within the desired range. Alternatively, if you wish to reduce the acetic acid content, you can adjust it by opening the vent cover to promote the volatilization of the acetic acid.

[0064] The content of acetic acid (C) in a resin composition can be measured by known methods. For example, acetic acid (C) can be extracted from the resin composition using a suitable solvent, the mass of the extracted acetic acid can be determined using a gas chromatograph-mass spectrometer (GC-MS), and the content can be determined from the relationship between the extracted acetic acid and the mass of the resin composition used.

[0065] When adding acetic acid (C) to a resin, it is preferable to add it as a mixed solution with a solvent rather than mixing it directly, in order to uniformly disperse the acetic acid (C).

[0066] Any known solvent can be used to prepare the mixed solution with acetic acid (C). Typical examples include ethanol, methanol, and propanol. Among these, ethanol and methanol are preferred.

[0067] When preparing a mixed solution of acetic acid (C) and a solvent, from the viewpoint of workability, the concentration of acetic acid (C) in the mixed solution is preferably 0.01 to 20% by mass, more preferably 0.05 to 15% by mass, and particularly preferably 0.1 to 10% by mass.

[0068] There is no particular lower limit to the combined content of polyolefin resin (A), polyvinyl alcohol resin (B), and acetic acid (C) in the resin composition, but from the viewpoint of functionality, it is preferable that it be 60% by mass or more, more preferably 70% by mass or more, and particularly preferable 80% by mass or more, based on the total amount of the resin composition. Furthermore, there is no particular upper limit to the combined content of polyolefin resin (A), polyvinyl alcohol resin (B), and acetic acid (C) in the resin composition, but from the viewpoint of functionality, it is preferable that it be 100% by mass or less, more preferably 99% by mass or less, and particularly preferable 98% by mass or less, based on the total amount of the resin composition. In one embodiment, the combined content of polyolefin resin (A), polyvinyl alcohol resin (B), and acetic acid (C) can be 60 to 100% by mass, more preferably 70 to 100% by mass, based on the total amount of the resin composition.

[0069] [Acid-modified polyolefin resin (D)] The resin composition according to this embodiment may further contain an acid-modified polyolefin resin (D). An acid-modified polyolefin resin is a resin in which an acid is introduced to a polyolefin resin by copolymerization or post-reaction.

[0070] As the acid-modified polyolefin resin (D), any known resin may be used. Such acid-modified polyolefin resins may be selected as appropriate, but typically, modified olefin resins containing carboxyl groups can be obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by addition reaction, graft reaction, etc. Among these, maleic anhydride-modified polyolefins are more preferred, and maleic anhydride-graft modified polyolefins are particularly preferred.

[0071] Examples of maleic anhydride-modified polyolefins include maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene-propylene (block and random) copolymer, maleic anhydride-grafted ethylene-ethyl acrylate (block and random) copolymer, and maleic anhydride-grafted ethylene-vinyl acetate (block and random) copolymer. One or more of these selected materials are preferred.

[0072] The melting point of the acid-modified polyolefin resin (D) is preferably 100 to 190°C, more preferably 100 to 180°C, and particularly preferably 100 to 170°C. This melting point was measured by DSC in accordance with JIS K7121:2012.

[0073] The melt flow rate (MFR) (according to JIS K7210:2014: 230°C, load 21.2N) of the acid-modified polyolefin resin (D) is preferably 0.1 to 50 g / 10 min, and more preferably about 0.5 to 30 g / 10 min.

[0074] There is no particular lower limit to the content of acid-modified polyolefin resin (D) in the resin composition, but from the viewpoint of compatibility, it is preferable that it be 0% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and particularly preferable 2% by mass or more, relative to the total amount of the resin composition. Furthermore, there is no particular upper limit to the content of acid-modified polyolefin resin (D) in the resin composition, but from the viewpoint of economy, it is preferable that it be 15% by mass or less, even more preferably 12.5% ​​by mass or less, and particularly preferable 10% by mass or less, relative to the total amount of the resin composition. In one embodiment, the acid-modified polyolefin resin (D) can be contained in an amount of 0.5 to 15% by mass, more preferably 1 to 12.5% ​​by mass, and even more preferably 2 to 10% by mass, relative to the total amount of the resin composition.

[0075] [Other Components] The resin composition according to this embodiment may further contain other components other than those described above.

[0076] Other components that can be used include, for example, antioxidants, heat stabilizers, light stabilizers, lubricants, antistatic agents, crystal nucleating agents, plasticizers, colorants, UV absorbers, surfactants, compatibilizers, regrinding aids, antibacterial agents, antiviral agents, desiccants, oxygen absorbers, antiblocking agents, slip agents, and inorganic / organic fillers, in order to improve moldability, physical properties, etc.

[0077] If the resin composition according to this embodiment contains other components, from the viewpoint of safety and efficacy, the content of these components relative to the total amount of the resin composition is preferably 0.01 to 10% by mass, more preferably 0.025 to 8% by mass, and particularly preferably 0.05 to 5% by mass.

[0078] [Method for producing a resin composition] A resin composition can be obtained by blending and mixing a polyolefin resin (A), a polyvinyl alcohol resin (B), and acetic acid (C), and optionally an acid-modified polyolefin resin (D) and other components. In one embodiment, a resin composition can be obtained by adding acetic acid (C) to a mixed resin containing a polyolefin resin (A), a polyvinyl alcohol resin (B), and optionally an acid-modified polyolefin resin (D), and mixing. When adding acetic acid (C) to the mixed resin, from the viewpoint of dispersibility, it is preferable to prepare a mixed solution by mixing acetic acid with a suitable solvent and add this using a spray or the like, or to impregnate the mixed resin into the mixed solution.

[0079] The resin composition obtained above can be supplied directly to the extruder for molded products, or it can be pelletized beforehand using a melt kneader such as a single-screw or twin-screw extruder using a known method, and then supplied to the extruder for molded products. The melt molding temperature during the melt extrusion described above is usually selected from the range of 150 to 300°C.

[0080] [Physical Properties of the Resin Composition] The MFR (Mold Fuel Rate) of the resin composition according to this embodiment (according to JIS K7210:2014: 230°C, load 21.2N) is preferably 0.5 to 20 g / 10 min. Having the MFR within the above range has the advantage of making it less likely for drawdown to occur during molding and making it easier to obtain a film with uniform thickness.

[0081] Furthermore, the resin composition used for the above molding process can be molded into any shape, such as films, sheets, tapes, cups, trays, tubes, bottles, pipes, filaments, extruded products with irregular cross-sections, and various irregularly shaped products.

[0082] Furthermore, in molding, heat stretching is often performed to improve the physical properties of the molded product or to mold it into any desired container shape. Here, heat stretching refers to the operation of uniformly molding a thermally heated film, sheet, or parison-shaped molded product into a cup, tray, tube, bottle, or film shape using a chuck, plug, vacuum force, compressed air, blow, etc. Examples of stretching methods include roll stretching, tenter stretching, tubular stretching, stretch blowing, vacuum forming, compressed air forming, and vacuum compressed air forming. Either uniaxial stretching or biaxial stretching may be used, but in the case of biaxial stretching, either simultaneous biaxial stretching or sequential biaxial stretching can be employed. The stretching temperature is usually 60 to 170°C, and more preferably 80 to 160°C.

[0083] In addition to the examples of molded products described above, the resin composition is generally used as at least one layer in a laminate containing it. Below, a laminate containing a layer obtained from the resin composition according to this embodiment (hereinafter also referred to as "the layer according to this embodiment") will be described in detail.

[0084] [Laminate containing the layer according to this embodiment] The laminate containing the layer according to this embodiment only needs to have at least one layer containing the above resin composition, and generally, a laminate containing a polyolefin resin layer, a PVA layer, and an adhesive resin layer as needed, in addition to the layer according to this embodiment is preferred. In this specification, "polyolefin resin layer" means a layer containing only a polyolefin resin as a resin component, "PVA layer" means a layer containing only a polyvinyl alcohol resin as a resin component, and "adhesive resin layer" means a layer containing an adhesive resin.

[0085] Specific layer configurations of a laminate containing the layer according to this embodiment include, for example, a polyolefin resin layer / layer according to this embodiment / adhesive resin layer / PVA layer, a polyolefin resin layer / layer according to this embodiment / adhesive resin layer / PVA layer / adhesive resin layer / polyolefin resin layer, a polyolefin resin layer / layer according to this embodiment / adhesive resin layer / PVA layer / adhesive resin layer / layer according to this embodiment / polyolefin resin layer, and furthermore, a layer according to this embodiment / PVA layer, and the embodiment Examples include the layer / adhesive resin layer / PVA layer according to the embodiment, the layer / adhesive resin layer / PVA layer / adhesive resin layer / PVA layer according to this embodiment, the layer / adhesive resin layer / PVA layer / adhesive resin layer / polyolefin resin layer according to this embodiment, the layer / adhesive resin layer / PVA layer / adhesive resin layer / the layer / polyolefin resin layer according to this embodiment, the polyolefin resin layer / adhesive resin layer / PVA layer / the layer / PVA layer / adhesive resin layer / polyolefin resin layer, and so on.

[0086] The thickness of each layer in a laminate containing the layers according to this embodiment cannot be generalized as it depends on the layer configuration, the type of polyolefin resin, the application, the container form, the required physical properties, etc., but the thickness of the layers according to this embodiment is preferably 1 to 5000 μm, and more preferably 5 to 1000 μm. For any layer, the thickness of the PVA layer is preferably 0.1 to 200 μm, and more preferably 0.5 to 100 μm. The thickness of the polyolefin resin layer is usually 1 to 5000 μm, and more preferably 10 to 1000 μm. In addition, the thickness of the adhesive resin layer is preferably 1 to 400 μm, and more preferably 2 to 150 μm.

[0087] Furthermore, the thickness ratio of the layer / polyolefin resin layer in this embodiment is preferably 1 / 1 to 100, and more preferably 1 / 1 to 50. Also, the thickness ratio of the layer / PVA layer in this embodiment is preferably 100 / 1 to 100, and more preferably 100 / 1 to 50.

[0088] [Method for manufacturing a laminate containing the layers according to this embodiment] As a method for manufacturing a laminate containing the layers according to this embodiment, for example, it is possible to mold it using the same type of resin as the resin composition according to this embodiment as the material and in the same manner. Specifically, it can be manufactured using the polyolefin resin used in the polyolefin resin layer exemplified above, the polyvinyl alcohol resin used in the PVA layer, and the adhesive resin used in the adhesive resin layer, by the lamination method exemplified below.

[0089] Examples of lamination methods for the above-mentioned laminate include: a method of melt-extrude-laminating the resin composition according to this embodiment onto a film or sheet of polyvinyl alcohol-based resin; a method of melt-extrude-laminating the resin composition according to this embodiment onto a substrate made of a polyolefin layer; a method of co-extruding a polyvinyl alcohol-based resin or polyolefin-based resin with the resin composition according to this embodiment; and a method of dry-laminating a film or sheet of polyvinyl alcohol-based resin or polyolefin-based resin with a film or sheet of the resin composition according to this embodiment using an adhesive such as an organic titanium compound, isocyanate compound, polyester compound, or polyurethane compound. The melt molding temperature during the above-mentioned melt extrusion is preferably in the range of 150 to 300°C.

[0090] The laminate containing the layer according to this embodiment can be used as is in various shapes, but it is also preferable to subject the laminate to a heat stretching treatment in order to further improve its physical properties and mold it into any desired container shape.

[0091] Here, heat stretching refers to the operation of uniformly shaping a thermally uniformly heated film, sheet, or parison-shaped laminate into cups, trays, tubes, bottles, or films using chucks, plugs, vacuum force, compressed air, blowing, etc.

[0092] The stretching methods used in the above-mentioned heat stretching process include roll stretching, tenter stretching, tubular stretching, stretch blowing, vacuum forming, pressure forming, and vacuum pressure forming. In the case of biaxial stretching, either simultaneous biaxial stretching or sequential biaxial stretching can be employed. The stretching temperature is preferably 60 to 170°C, and more preferably around 80 to 160°C. Either uniaxial stretching or biaxial stretching is acceptable, and stretching at the highest possible magnification results in better physical properties, and a stretched molded product with excellent gas barrier properties can be obtained without the occurrence of pinholes, cracks, uneven stretching, uneven thickness, or delamination during stretching.

[0093] Furthermore, each layer of the laminate obtained by this embodiment may be enriched with antioxidants, heat stabilizers, light stabilizers, lubricants, antistatic agents, nucleating agents, plasticizers, colorants, ultraviolet absorbers, surfactants, compatibilizers, regrinding aids, antibacterial agents, antiviral agents, desiccants, oxygen absorbers, antiblocking agents, slip agents, inorganic and organic fillers, etc., to improve moldability, physical properties, etc., within limits that do not hinder the effects of the present invention.

[0094] The laminate described above can be formed not only into sheets and films, but also into pipes, tubes, tanks, bottles, and other containers using the same molding methods as described above. Furthermore, the laminate can be reheated to approximately 60 to 170°C and stretched using the same methods as described above, such as blow stretching or deep drawing (vacuum forming, pressure forming, vacuum pressure forming, etc.), to form into bottles, tubes, cups, trays, and other containers.

[0095] Furthermore, the resulting laminate can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or molten coating treatment, bag making, deep drawing, box making, tube making, splitting, etc., as needed.

[0096] The laminates obtained in this way are useful as containers for various products such as general foods, condiments like mayonnaise and dressings, fermented foods like miso, oily foods like salad oil, soups, beverages, cosmetics, pharmaceuticals, detergents, fragrances, industrial chemicals, pesticides, and fuels. In particular, they are useful as bottle-shaped or tube-shaped containers for semi-solid foods and condiments such as mayonnaise, ketchup, sauces, miso, wasabi, mustard, and yakiniku sauces; as well as for liquid beverages and condiments such as salad oil, mirin, sake, beer, wine, juice, tea, sports drinks, mineral water, and milk; as cup-shaped containers for semi-solid foods and condiments such as fruits, jelly, pudding, yogurt, mayonnaise, miso, processed rice, cooked foods, and soups; and as tray-shaped containers for raw meat, processed meat products (ham, bacon, wieners, etc.), cooked rice, and pet food.

[0097] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention.

[0098] First, prior to the examples, the following materials were prepared.

[0099] <Polyolefin Resins> Polyolefin Resin 1: Polyethylene [Density: 0.92 g / cm³] ３ MFR: 1.1 g / 10 min (measured in accordance with JIS K7210:2014), Melting point: 108°C (measured by DSC in accordance with JIS K7121:2012), Manufactured by Nippon Polyethylene Co., Ltd., Product name: Novatec ＴＭ LD YF30] Polyolefin resin 2 Polypropylene [Density: 0.90 g / cm³] ３ MFR: 1.9 g / 10 min (measured in accordance with JIS K7210:2014), Melting point: 165°C (measured by DSC in accordance with JIS K7121:2012), Manufactured by Nippon Polypropylene Co., Ltd., Product name: Novatec ＴＭ PP FY6H]

[0100] <Polyvinyl alcohol-based resin (PVA-based resin)> 1,2-diol-modified polyvinyl alcohol-based resin [Saponification degree 99 mol%, degree of polymerization 450, 1,2-diol modification 6 mol%, melting point: 188°C (measured by DSC in accordance with JIS K7121:2012)]

[0101] <Acid-modified polyolefin resins> Acid-modified polyolefin resin 1 Acid-modified polyethylene [Density: 0.94 g / cm³] ３ MFR: 0.3 g / 10 min (measured in accordance with JIS K7210:2014), Melting point: 133°C (measured by DSC in accordance with JIS K7121:2012), Manufactured by Mitsubishi Chemical Corporation, Product name "Modic" ＴＭ H511] Acid-modified polyolefin resin 2 Acid-modified polypropylene [MFR: 3.4 g / 10 min (measured in accordance with JIS K7210:2014), melting point: 141°C, measured by DSC in accordance with JIS K7121:2012), manufactured by Mitsubishi Chemical Corporation, product name "Modic ＴＭ P674V]

[0102] [Example 1-1] (Preparation of raw material composition) A mixed resin was prepared by mixing 1960 g of the polyolefin resin 1 described above, 20 g of polyvinyl alcohol resin, and 20 g of acid-modified polyolefin resin 1. Using a micropipette, 100 μL of acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and 10 mL of ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were measured out to prepare an acetic acid / ethanol mixed solution. The raw material composition was obtained by adding the acetic acid / ethanol mixed solution using a spray while mixing the mixed resin. In Example 1-1, the acetic acid addition rate to the mixed resin was 50 ppm by mass. The composition of the raw material compositions, including Example 1-2 and Comparative Examples 1-1 to 1-2 shown below, is shown in Table 1.

[0103] (Pellet Preparation) The obtained raw material composition was fed into the hopper of a twin-screw extruder and melt-kneaded at a screw rotation speed of 250 rpm. The resin extruded from the die was placed on a belt conveyor and solidified, and then cut into pellets using a pelletizer to produce pellets of the resin composition of Example 1-1. The conditions for pellet preparation are as described below.

[0104]

[0105] [Example 1-2] Pellets of the resin composition of Example 1-2 were prepared in the same manner as in Example 1-1, except that the amount of acetic acid in the acetic acid / ethanol mixed solution was 200 μL.

[0106] [Comparative Example 1-1] Pellets of the resin composition of Comparative Example 1-1 were prepared in the same manner as in Example 1-1, except that an acetic acid / ethanol mixed solution was not added.

[0107] [Comparative Example 1-2] Pellets of the resin composition of Comparative Example 1-2 were prepared in the same manner as in Example 1-1, except that the amount of acetic acid in the acetic acid / ethanol mixed solution was 1000 μL.

[0108] <Pellet Production Conditions> ・Twin-screw extruder: TEM-18DS (manufactured by Shibaura Machinery Co., Ltd.) ・Screw size: Diameter φ20 (L / D = 40) ・Temperature setting: C1 / C2 / C3 / C4 / C5 / C6 / H = 30 / 150 / 210 / 210 / 210 / 210 / 210 (°C) ・Screen mesh: 90 / 90 ・Die: 2 holes ・Discharge rate: 4-5 kg / h

[0109] <Pellet Evaluation> The granulated pellets were evaluated using the following method. The results are shown in Table 2.

[0110] [Acetic Acid Content] The obtained pellets were pulverized by freeze-grinding, and 2 g of the pulverized powder was weighed into a headspace vial. A stirring bar and 10 mL of dimethylformamide (DMF) were added to this vial, and it was sealed with a polytetrafluoroethylene (PTFE) septum-aluminum cap. The mixture was stirred at 70°C for about 1 hour to extract the acetic acid from the 2 g of pellets into the DMF layer. A fixed amount of the gas phase was introduced into a gas chromatograph-mass spectrometer (GC-MS) using a headspace sampler, and the acetic acid content in the sample (acetic acid content), i.e., the acetic acid content relative to the total amount of resin composition, was determined from the calibration curve of the standard solution. Details of the headspace sampler and GC-MS used are described below.

[0111] For quantitative analysis, acetic acid was weighed, diluted to the correct volume with DMF, and then graded to create the standard solution. Ten ml of the standard solution was taken into a headspace vial, a stirring bar was added, and the vial was sealed in the same manner as used for pellet measurement. This sample was then used as the calibration curve sample.

[0112] (Headspace Sampler) • Device: G1888 (Agilent Technologies) • Oven Temperature: 70°C • Loop Temperature: 140°C • Transfer Line Temperature: 150°C • Vial Equilibrium Time: 30 min • Loop Fill Pressure: 20 psi → 2 psi • Injection Loop Volume: 1 mL • Shaking: None

[0113] (Gas Chromatograph-Mass Spectrometer (GC-MS)) • GC Instrument: 7890B (Agilent Technologies) • MS Instrument: 5977B (Quadrupole Mass Spectrometer) (Agilent Technologies) • Column: DB-WAX 30m × 0.25mm × 0.25μm (Agilent Technologies) • Carrier Gas Type and Flow Rate: Helium, 1 mL / min • Temperature (Oven): 40°C (5 min) → Rate 10°C / min → 250°C (5 min) • Temperature (Injection): 250°C • Temperature (Auxiliary Device): Transfer Line = 250°C • Injection Mode: Split Injection Method, Split Ratio: 1 / 5 • Detector: Mass Spectrometer (Electron Multiplier Tube) • Ionization method: Electron bombardment method • Scanning range: SIM • Acetate quantitative ion (m / z 43), confirmation ion (m / z 60)

[0114] [Melt Flow Rate (MFR)] The MFR was measured in accordance with JIS K7210:2014 at a temperature of 210°C and a load of 21.2 N.

[0115] [Yellow Index (YI)] The YI of the pellets was measured using a spectrophotometer SE6000 (manufactured by Nippon Denshoku Industries Ltd.).

[0116]

[0117] The results above indicate that the resin composition of the present invention has a low yellow index. This suggests that the resin composition of the present invention exhibits minimal coloration.

[0118] [Example 2-1] (Preparation of raw material composition) A mixed resin was prepared by mixing 1960 g of the polyolefin resin 2 described above, 20 g of polyvinyl alcohol resin, and 20 g of acid-modified polyolefin resin 2. Using a micropipette, 100 μL of acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and 10 mL of ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were measured out to prepare an acetic acid / ethanol mixed solution. The raw material composition was obtained by adding the acetic acid / ethanol mixed solution using a spray while mixing the mixed resin. In Example 2-1, the acetic acid addition rate to the mixed resin was 50 ppm by mass. The composition of the raw material compositions, including Examples 2-2 to 2-3 and Comparative Examples 2-1 to 2-3 shown below, is shown in Table 3.

[0119] (Pellet Preparation) The obtained raw material composition was fed into the hopper of a twin-screw extruder, and then melted and kneaded with the vent open at a screw rotation speed of 250 rpm. The resin discharged from the die was placed on a belt conveyor, and after the resin solidified, it was cut into pellets using a pelletizer to produce pellets of the resin composition of Example 2-1. The pellet preparation conditions were as described above.

[0120] [Example 2-2] Pellets of the resin composition of Example 2-2 were prepared in the same manner as in Example 2-1, except that the amount of acetic acid in the acetic acid / ethanol mixed solution was 200 μL.

[0121] [Example 2-3] Pellets of the resin composition of Example 2-3 were prepared in the same manner as in Example 2-1, except that the amount of acetic acid in the acetic acid / ethanol mixed solution was 1000 μL. The composition of the raw material composition is shown in Table 3.

[0122] [Comparative Example 2-1] Pellets of the resin composition of Comparative Example 2-1 were prepared in the same manner as in Example 2-1, except that an acetic acid / ethanol mixed solution was not added.

[0123] [Comparative Example 2-2] Pellets of the resin composition of Comparative Example 2-2 were prepared in the same manner as in Example 2-3, except that the amount of acetic acid in the acetic acid / ethanol mixed solution was 1000 μL and the vent holes were covered.

[0124] [Comparative Example 2-3] Pellets of the resin composition of Comparative Example 2-3 were prepared in the same manner as in Example 1-1, except that the amount of acetic acid in the acetic acid / ethanol mixed solution was 2000 μL.

[0125]

[0126] <Pellet Evaluation> The granulated pellets were evaluated using the following method. The results are shown in Table 4.

[0127] [Acetic Acid Content] The acetic acid content of the granulated pellets was evaluated using the method described above.

[0128] [Melt Flow Rate (MFR), Yellow Index (YI)] MFR and YI were measured as described above.

[0129]

[0130] The results above indicate that the resin composition of the present invention has a low yellow index. This suggests that the resin composition of the present invention exhibits minimal coloration.

[0131] Although various embodiments have been described above, it goes without saying that the present invention is not limited to these examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. Furthermore, the components in the above embodiments may be combined in any way without departing from the spirit of the invention.

[0132] This application is based on a Japanese patent application (Patent Application No. 2025-067736) filed on April 16, 2025, the contents of which are incorporated herein by reference.

[0133] The resin composition of the present invention contains a polyolefin resin (A), a polyvinyl alcohol resin (B), and acetic acid (C), with the content of acetic acid (C) being 10 ppm by mass or more and less than 60 ppm by mass relative to the total amount. Due to this composition, the resin composition of the present invention exhibits the excellent effect of having minimal coloration. Laminates obtained from the resin composition of the present invention are useful, for example, as containers.

Claims

1. A resin composition containing a polyolefin resin (A), a polyvinyl alcohol resin (B), and acetic acid (C), wherein the content of acetic acid (C) relative to the total amount is 10 ppm by mass or more and less than 60 ppm by mass.

2. The resin composition according to claim 1, comprising at least one selected from the group consisting of polyethylene and polypropylene as the polyolefin resin (A).

3. The resin composition according to claim 1 or 2, comprising a modified polyvinyl alcohol resin as the polyvinyl alcohol resin (B).

4. The resin composition according to claim 3, wherein the amount of modification of the modified polyvinyl alcohol resin is 1 to 20 mol% with respect to the vinyl alcohol units in the polyvinyl alcohol main chain.

5. The resin composition according to claim 3, wherein the modified polyvinyl alcohol resin is a modified polyvinyl alcohol resin containing a structural unit having a primary hydroxyl group in its side chain.

6. The resin composition according to claim 1 or 2, wherein the content of acetic acid (C) is 58 ppm by mass or less based on the total amount of the resin composition.

7. The resin composition according to claim 1 or 2, wherein the content of acetic acid (C) is 55 ppm by mass or less based on the total amount of the resin composition.

8. The resin composition according to claim 1 or 2, comprising 70 to 99% by mass of polyolefin resin (A) based on the total amount of the resin composition.

9. The resin composition according to claim 1 or 2, comprising 0.1 to 15% by mass of a polyvinyl alcohol-based resin (B) based on the total amount of the resin composition.

10. The resin composition according to claim 1 or 2, comprising 60 to 100% by mass of a polyolefin resin (A), a polyvinyl alcohol resin (B), and acetic acid (C) in total, based on the total amount of the resin composition.

11. The resin composition according to claim 1 or 2, further comprising an acid-modified polyolefin resin (D).

12. The resin composition according to claim 1 or 2, comprising 0.5 to 15% by mass of an acid-modified polyolefin resin (D) based on the total amount of the resin composition.

13. A laminate having at least one layer containing the resin composition described in claim 1 or 2.

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