Resin composition

Abstract

Provided is a resin composition which, even when a biopolyethylene resin is used, makes it possible to obtain a molded article that is suppressed in the occurrence of material deposition and has an excellent appearance, and which contains: a biopolyethylene resin (A); an ethylene-vinyl alcohol copolymer (B) having an ethylene content of 20-60 mol%; and at least one component (C) selected from the group consisting of ethylene-vinyl acetate copolymers, acid-modified ethylene-alpha-olefin copolymers, ethylene-unsaturated monocarboxylic acid copolymers, ionomers of ethylene-unsaturated monocarboxylic acid copolymers, ethylene-vinyl alcohol copolymers having an ethylene content of 70-90 mol%, and hydrotalcite.

Description

[0001] This application is a divisional application of the application filed on August 7, 2020, with application number 202080050937.3 and entitled "Resin Composition". Technical Field

[0002] This invention relates to resin compositions, and more specifically, to resin compositions that can produce molded articles with excellent appearance while suppressing material buildup even when using bio-based polyethylene resins. Background Technology

[0003] Previously, ethylene-vinyl alcohol copolymers have excellent gas barrier properties and transparency, and therefore are mainly used as food packaging materials. Sheets, films, etc., used as the above-mentioned food packaging materials can be made from the above-mentioned ethylene-vinyl alcohol copolymers alone, but in order to impart water resistance, strength, and other functions, they are usually used as multilayer structures made by laminating polyolefin resins, etc. with adhesives.

[0004] In addition, sometimes waste materials such as molded parts, ends, and defective products generated after manufacturing containers or other molded articles from the aforementioned multi-layered structures are recycled and melt-molded. This recycled material is then reused as a reuse layer (hereinafter sometimes referred to as a "recycled material layer") in at least one layer of the multi-layered structure. When using such recycled material, it is required to prevent discoloration of the molded article, suppress the accumulation of decomposition products from ethylene-vinyl alcohol copolymers, and produce a molded article with excellent appearance.

[0005] On the other hand, in recent years, in order to reduce the environmental impact, a scheme has been studied to replace some of the resins used in the above-mentioned multilayer structures with resins derived from petroleum-based resources such as plants (for example, see Patent Documents 1-3).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2014-200968

[0009] Patent Document 2: Japanese Patent Application Publication No. 2014-104729

[0010] Patent Document 3: Japanese Patent Application Publication No. 2014-213903 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] However, when a resin composition containing ethylene-vinyl alcohol copolymer and biomass-derived polyethylene resin is melt-molded, the biomass-derived polyethylene resin contains a large amount of low molecular weight components compared to petroleum-derived polyethylene resin. As a result, polyethylene resin residue is expelled from the resin composition. As the content of biomass-derived polyethylene resin increases, discoloration and polyethylene resin residue increase, leading to a decline in appearance. Therefore, further improvements are sought.

[0013] Therefore, the present invention provides a resin composition that can suppress the accumulation of polyethylene resin during molding and suppress discoloration and other appearance degradation of the molded article when using polyethylene resin derived from biomass resources.

[0014] Solution for solving the problem

[0015] In view of the above-mentioned actual situation, the inventors conducted in-depth research and found that the above-mentioned problems can be solved by blending a specific component (C) into a base polymer containing a bio-polyethylene resin (A) and an ethylene-vinyl alcohol copolymer (B) with an ethylene content of 20 to 60 mol%.

[0016] That is, the main purpose of this invention is to provide a resin composition comprising: a bio-polyethylene resin (A); an ethylene-vinyl alcohol copolymer with an ethylene content of 20-60 mol% (B); and at least one component (C) selected from the group consisting of ethylene-vinyl acetate copolymer, acid-modified ethylene-α-olefin copolymer, ethylene-unsaturated monocarboxylic acid copolymer, ionomer of ethylene-unsaturated monocarboxylic acid copolymer, ethylene-vinyl alcohol copolymer with an ethylene content of 70-90 mol%, and hydrotalcite.

[0017] The effects of the invention

[0018] The resin composition of the present invention is a resin composition containing at least one component (C) selected from the group consisting of a bio-polyethylene resin (A), an ethylene-vinyl alcohol copolymer with an ethylene content of 20-60 mol%, and an ethylene-vinyl acetate copolymer, an acid-modified ethylene-α-olefin copolymer, an ethylene-unsaturated monocarboxylic acid copolymer, an ionomer of an ethylene-unsaturated monocarboxylic acid copolymer, an ethylene-vinyl alcohol copolymer with an ethylene content of 70-90 mol%, and hydrotalcite. Therefore, the resin composition of the present invention can suppress the accumulation of bio-polyethylene resin during molding, and also suppress discoloration and other appearance degradation of the molded article.

[0019] In addition, when the content of the above-mentioned component (C) is 0.1 to 30 parts by weight relative to the total of 100 parts by weight of bio-polyethylene resin (A) and ethylene-vinyl alcohol copolymer (B) with an ethylene content of 20 to 60 mol%, it can further suppress the accumulation of bio-polyethylene resin during molding, and further suppress the appearance degradation of the molded article, such as discoloration.

[0020] Furthermore, when the weight ratio of the above-mentioned bio-polyethylene resin (A) to the above-mentioned ethylene-vinyl alcohol copolymer (B) with an ethylene content of 20 to 60 mol% [(A) / (B)] is 0.1 / 99.9 to 99.9 / 0.1, it can make the moldability during molding and the barrier properties of the molded product excellent. Detailed Implementation

[0021] The following describes in detail the methods for implementing the present invention, but the present invention is not limited thereto.

[0022] In addition, in this invention, "ethylene-vinyl alcohol copolymer with ethylene content of 20 to 60 mol%" is sometimes referred to as "EVOH".

[0023] The resin composition of the present invention is obtained by blending specific components (C) into a base polymer formed from bio-based polyethylene resin (A) and EVOH (B). The components will be described below.

[0024] [Bio-based polyethylene resin (A)]

[0025] The aforementioned "biopolymer polyethylene resin" refers to polyethylene resin synthesized from renewable biomass resources through chemical or biological methods. This biopolymer polyethylene resin has the following characteristics: when incinerated, it does not increase the concentration of carbon dioxide in the atmosphere due to the carbon neutrality of biomass.

[0026] The aforementioned bio-based polyethylene resin (A) preferably uses plant-derived ethylene from which bioethanol is derived. That is, the aforementioned bio-based polyethylene resin (A) is preferably a plant-derived polyethylene resin.

[0027] Plant-based (biomass resource) polyethylene resins and petroleum-based polyethylene resins do not differ in physical properties such as molecular weight and mechanical / thermal properties. Therefore, biomass content is commonly used to distinguish them. The aforementioned biomass content refers to the percentage of carbon contained in petroleum-based polyethylene resins. 14 C (radioactive carbon-14, half-life 5730 years), therefore, the determination of this by accelerator mass spectrometry analysis 14The concentration of C serves as an indicator of the proportion of plant-derived biopolymer polyethylene resin. Therefore, if a film using plant-derived polyethylene resin is being produced, the biomass of the film should be determined based on the content of the plant-derived polyethylene resin. That is, biopolymer polyethylene resin (A) is characterized by containing radioactive carbon (C). 14 C).

[0028] The aforementioned biomass quality can be determined, for example, by the following method: The sample to be tested is burned to produce carbon dioxide. Using iron as a catalyst, the carbon dioxide, purified on a vacuum production line, is reduced in hydrogen to produce graphite. This graphite is then installed in a tandem accelerator-based system. 14 C-AMS dedicated device (manufactured by NEC) is used for... 14 Counting C 13 The concentration of C ( 13 C / 12 C) 14 The concentration of C ( 14 C / 12 C) is determined, and the carbon content of the sample is calculated from the measured value. 14 The ratio of C concentration to modern carbon standards.

[0029] Examples of the aforementioned bio-based polyethylene resin (A) include, for instance, polyethylene homopolymers and polyethylene copolymers obtained by polymerizing ethylene derived from bioethanol. These polyethylene copolymers are copolymers of ethylene and a small amount of comonomers, for example, formed from ethylene and other α-olefin monomers with a weight fraction of less than 50%, or non-olefin monomers with functional groups with a weight fraction of less than 3%.

[0030] Other α-olefins mentioned above include those with 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetracene, 1-tetradecene, 1-pentadecadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecadecene, 1-eicosene, and 3-methyl 1-Butene, 4-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, etc. They can be used alone or in combination of two or more.

[0031] Examples of non-olefin monomers mentioned above include styrene monomers, diene monomers, cyclic monomers, and monomers containing oxygen atoms. They can be used alone or in combination of two or more.

[0032] Examples of styrene monomers include styrene, 4-methylstyrene, and 4-dimethylaminostyrene.

[0033] Examples of diene monomers mentioned above include 1,3-butadiene, 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,4-octadiene, 1,5-octadiene, 1,6-octadiene, 1,7-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, 4-ethide-8-methyl-1,7-nonadiene, 4,8-dimethyl-1,4,8-decanetriene (DMDT), dicyclopentadiene, cyclohexadiene, and dicyclooctadiene.

[0034] Examples of the aforementioned cyclic monomers include methylene norbornene, 5-vinyl norbornene, 5-ethide-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornediene, and cyclopentene.

[0035] Examples of the aforementioned oxygen-containing monomers include hexenol, hexenoic acid, and methyl octenate.

[0036] The other α-olefin and non-olefin monomers mentioned above can use renewable biomass resources or petroleum as raw materials. Using renewable biomass resources as raw materials allows for further improvement in the biomass content of the final product. Furthermore, using petroleum as a raw material yields a variety of products; therefore, by using these materials in manufacturing, the physical properties of polyethylene resins can be easily adjusted.

[0037] The aforementioned biopolymerized polyethylene resin (A) is obtained by homopolymerization of ethylene or copolymerization of ethylene with comonomers. The polymerization or copolymerization can be carried out using metallocene catalysts or Ziegler-Natta catalysts according to conventional methods. Among these methods, metallocene catalysts are preferred.

[0038] Specifically, examples of the aforementioned bio-based polyethylene resin (A) include, for instance, high-density polyethylene (HDPE, density 0.940 g / cm³). 3 (above), medium-density polyethylene (MDPE, density ≥ 0.925 g / cm³) 3Low-density polyethylene (LDPE, density less than 0.925 g / cm³) 3 Linear low-density polyethylene (LLDPE, density 0.910~0.925g / cm³) 3 These can be used individually or in combination of two or more. Among them, high-density polyethylene and linear low-density polyethylene are preferred.

[0039] The melt flow rate (MFR) of the above-mentioned bio-based polyethylene resin (A) (190°C, 2160g load) is typically 0.1 to 50 g / 10 min, preferably 0.5 to 30 g / 10 min, and particularly preferably 2 to 10 g / 10 min.

[0040] When the MFR is too high, the film-forming properties tend to become unstable; when the MFR is too low, the viscosity becomes excessively high, and melt extrusion tends to become difficult.

[0041] Commercially available bio-based polyethylene resins (A) suitable for use in this invention include, for example, green PE manufactured by Braskem S.A.

[0042] In addition, the above-mentioned bio-based polyethylene resin (A) can be used alone or in combination of two or more types.

[0043] [EVOH(B)]

[0044] The aforementioned EVOH(B) is typically a resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and a vinyl ester monomer, and is a non-water-soluble thermoplastic resin. From an economic perspective, vinyl acetate is usually used as the aforementioned vinyl ester monomer.

[0045] The polymerization of ethylene and vinyl ester monomers can be carried out using any known polymerization method, such as solution polymerization, suspension polymerization, or emulsion polymerization. Solution polymerization using methanol as a solvent is commonly used. The saponification of the resulting ethylene-vinyl ester copolymer can also be carried out using known methods.

[0046] The EVOH(B) produced in this way mainly contains ethylene-derived structural units and vinyl alcohol structural units, and usually contains a certain amount of vinyl ester structural units that remain unsaponified.

[0047] Vinyl acetate is representatively used as one of the aforementioned vinyl ester monomers due to its market availability and efficient impurity removal during manufacturing. Other vinyl ester monomers include, for example, aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl decanoate, vinyl laurate, vinyl stearate, and vinyl tert-carbonate, and aromatic vinyl esters such as vinyl benzoate. Aliphatic vinyl esters with 3 to 20 carbon atoms are typically used, preferably 4 to 10, and particularly preferably 4 to 7. These can be used alone or in combination of two or more.

[0048] The ethylene content in the above-mentioned EVOH(B) can be controlled according to the pressure of the ethylene during copolymerization of the vinyl ester monomers and ethylene, and is 20 to 60 mol%. Preferably, it is 25 to 50 mol%, and particularly preferably, it is 25 to 35 mol%. If the above content is too low, there is a tendency for reduced gas barrier properties and melt formability under high humidity. Conversely, if the above content is too high, there is a tendency for reduced gas barrier properties.

[0049] It should be noted that the ethylene content mentioned above can be determined based on ISO 14663.

[0050] Furthermore, the degree of saponification of the vinyl ester component in EVOH(B) can be controlled based on the amount of saponification catalyst (usually an alkaline catalyst such as sodium hydroxide) during the saponification of the ethylene-vinyl ester copolymer, temperature, and time, and is typically 90–100 mol%, preferably 95–100 mol%, and particularly preferably 99–100 mol%. If the saponification is too low, there is a tendency for a decrease in gas barrier properties, thermal stability, and moisture resistance.

[0051] The degree of saponification of the above-mentioned EVOH can be determined based on JIS K6726 (wherein EVOH is used as a solution obtained by uniformly dissolving in water / methanol solvent).

[0052] Furthermore, the melt flow rate (MFR) of the aforementioned EVOH (210°C, 2160g load) is typically 0.5–100g / 10min, preferably 1–50g / 10min, and particularly preferably 3–35g / 10min. If the MFR is too high, the film-forming properties tend to become unstable; if the MFR is too low, the viscosity tends to become excessively high, making melt extrusion difficult.

[0053] The MFR mentioned above, as an indicator of the degree of polymerization of EVOH, can be adjusted according to the amount of polymerization initiator and solvent used when copolymerizing ethylene with vinyl ester monomers.

[0054] In addition, within a range that does not impair the effects of the present invention (e.g., less than 10 mol% of EVOH), the EVOH may also contain structural units derived from the comonomers shown below.

[0055] Examples of the aforementioned comonomers include: olefins such as propylene, 1-butene, and isobutene; hydroxyl-containing α-olefins such as 3-buten-1-ol, 3-buten-1,2-diol, 4-penten-1-ol, and 5-hexen-1,2-diol, and their esterified and acylated derivatives; hydroxyalkyl vinylides such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; and 1,3-diacetoxy-2-methylenepropane and 1,3-dipropionyloxy-2-methylenepropane. Hydroxyalkyl vinylidene diacetate esters such as methylpropane and 1,3-dibutyryloxy-2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, phthalic acid (anhydride), maleic acid (anhydride), itaconic acid (anhydride), or their salts, or mono- or dialkyl esters with alkyl groups having 1 to 18 carbon atoms; acrylamide, N-alkylacrylamide, N,N-dimethylacrylamide, 2-acrylamidopropane sulfonic acid or their salts, acrylamide propyl dimethylamine or their salts. Acrylamides such as acid salts or their quaternary salts; methacrylamides, N-alkylmethacrylamides with alkyl groups having 1 to 18 carbon atoms, N,N-dimethylmethacrylamide, 2-methacrylamide propane sulfonic acid or its salts, methacrylamide propyl dimethylamine or its acid salts or their quaternary salts, etc.; N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, etc.; cyanide vinyl derivatives such as acrylonitrile and methacrylonitrile; alkyl groups having 1 to 18 carbon atoms. 8. Alkyl vinyl ethers, hydroxyalkyl vinyl ethers, alkoxyalkyl vinyl ethers, and other vinyl ethers; halogenated vinyl compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; halogenated allyl compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; and comonomers such as trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride and acrylamide-2-methylpropanesulfonic acid. These can be used alone or in combination of two or more.

[0056] In terms of maintaining gas barrier properties and improving secondary molding properties, EVOH having primary hydroxyl groups in the side chain is particularly preferred, wherein EVOH copolymerized from hydroxyl-containing α-olefins is preferred, and EVOH having a 1,2-diol structure in the side chain is particularly preferred.

[0057] Especially in the case of EVOH with a primary hydroxyl group in the side chain, the content of the structural unit derived from the monomer having the primary hydroxyl group is preferably 0.1 to 20 mol% of EVOH, more preferably 0.5 to 15 mol%, and particularly preferably 1 to 10 mol%.

[0058] In addition, the EVOH(B) used in this invention can be a product that has undergone "post-modification" such as urethane esterification, acetalization, cyanoethylation, or oxidative olefination.

[0059] Furthermore, the EVOH(B) used in this invention can be a mixture of two or more types of EVOH(B), such as those with different degrees of saponification, different degrees of polymerization, or different copolymer components.

[0060] The weight ratio of the aforementioned bio-polyethylene resin (A) to the aforementioned EVOH (B) in the resin composition of the present invention [(A) / (B)] is preferably 0.1 / 99.9 to 99.9 / 0.1, more preferably 20 / 80 to 99 / 1, and particularly preferably 25 / 75 to 95 / 5. If the proportion of bio-polyethylene resin (A) is too small, there is a tendency for reduced moldability at low temperatures; on the other hand, if the proportion of bio-polyethylene resin (A) is too large, there is a tendency for reduced barrier properties.

[0061] The base polymers in the resin composition of the present invention are bio-based polyethylene resin (A) and EVOH (B), and the content of the base polymers in the resin composition is typically 60% by weight or more, preferably 70% by weight or more, and particularly preferably 80% by weight or more. Furthermore, the upper limit of the content of the base polymers is typically 99.9% by weight.

[0062] By compounding a specific component (C) into the aforementioned base polymer, the accumulation of bio-based polyethylene resin during molding can be suppressed, and the degradation of appearance, such as discoloration, can be prevented. Furthermore, by compounding component (C), when forming granules, there is a tendency to increase the bulk density, and when filling bags, there is a tendency to achieve dense filling.

[0063] In this invention, the content of the aforementioned component (C) is preferably set to 0.1 to 30 parts by weight relative to 100 parts by weight of the total amount of bio-polyethylene resin (A) and EVOH (B). By keeping the content of component (C) within the above range, discoloration of the molded article and the reduction in the appearance of the molded article caused by the accumulation of bio-polyethylene resin during molding can be further suppressed. In addition, the bulk density when forming granules can be further improved. The content of the aforementioned component (C) is preferably 0.2 to 20 parts by weight, and particularly preferably 0.5 to 10 parts by weight relative to 100 parts by weight of the total amount of bio-polyethylene resin (A) and EVOH (B). Furthermore, when the resin composition contains two or more components (C), the total content of all of them is taken as the content of component (C).

[0064] The specific component (C) mentioned above is selected from at least one of the following groups: ethylene-vinyl acetate copolymer, acid-modified ethylene-α-olefin copolymer, ethylene-unsaturated monocarboxylic acid copolymer, ionomer of ethylene-unsaturated monocarboxylic acid copolymer, ethylene-vinyl alcohol copolymer with an ethylene content of 70-90 mol%, and hydrotalcite. Component (C) will be described below.

[0065] [Ethylene-vinyl acetate copolymer]

[0066] The aforementioned ethylene-vinyl acetate copolymer (hereinafter, sometimes referred to as "EVA") is a polymer obtained by copolymerizing ethylene and vinyl acetate. Furthermore, EVA can be modified as needed.

[0067] The vinyl acetate content in the aforementioned EVA is typically 1–60 mol%, preferably 5–50 mol%, and particularly preferably 10–40 mol%. If the vinyl acetate content is too low, there is a tendency for insufficient material accumulation suppression and inadequate improvement in the appearance of the molded product. Conversely, if the vinyl acetate content is too high, the decomposition temperature of the EVA is low, and acetic acid is produced during decomposition, which may damage the mechanical properties. Furthermore, there is a tendency for a decrease in the thermal stability of the resin composition itself.

[0068] The melt flow rate (MFR) of the above-mentioned EVA (190°C, 2160g load) is typically 0.1 to 100 g / 10 min, preferably 0.5 to 50 g / 10 min, and particularly preferably 1 to 30 g / 10 min. If the MFR is outside the above range, there is a tendency for reduced compatibility with the base polymer and reduced dispersibility during mixing.

[0069] The aforementioned EVA, without hindering the spirit of the present invention, can be a modified form containing a carboxyl group obtained by chemically combining unsaturated carboxylic acids or their anhydrides through addition reactions, grafting reactions, etc. The amount of modification is preferably, for example, 10 mol% or less. Examples of the aforementioned unsaturated carboxylic acids or their anhydrides include, for example, olefinic unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethylacrylic acid, and crotonic acid; olefinic unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid, maleic acid, monomethyl maleate, and monoethyl maleate; their anhydrides; and their total esters. Maleic anhydride is preferred.

[0070] The EVA content, relative to 100 parts by weight of the total amount of bio-based polyethylene resin (A) and EVOH (B), is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 20 parts by weight, and particularly preferably 1 to 10 parts by weight. If the EVA content is within the above range, it can further suppress the accumulation of bio-based polyethylene resin during molding and suppress discoloration and other appearance degradation of the molded article. Furthermore, the EVA can be used alone or in combination with two or more types of EVA having different ethylene content, molecular weight, MFR, density, modified groups, and amounts of modification.

[0071] [Acid-modified ethylene-α-olefin copolymer]

[0072] The aforementioned acid-modified ethylene-α-olefin copolymer can be obtained by copolymerizing a portion of the monomers constituting the ethylene-α-olefin copolymer with α,β-unsaturated carboxylic acids or their anhydrides, or by introducing α,β-unsaturated carboxylic acids or their anhydrides into a portion of the side chain of the ethylene-α-olefin copolymer using grafting reactions such as free radical addition. The acid-modified ethylene-α-olefin copolymer mentioned above excludes the ethylene-unsaturated monocarboxylic acid copolymers described later.

[0073] Examples of ethylene-α-olefin copolymers include copolymers of ethylene with α-olefins having 3 to 20 carbon atoms (preferably 3 to 10). Specifically, examples include ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-1-hexene copolymers, ethylene-4-methyl-1-pentene copolymers, ethylene-1-octene copolymers, ethylene-1-butene-1-hexene copolymers, ethylene-1-butene-4-methyl-1-pentene copolymers, and ethylene-1-butene-1-octene copolymers. Ethylene-1-butene copolymers, ethylene-1-hexene copolymers, ethylene-1-octene copolymers, ethylene-1-butene-1-hexene copolymers, and ethylene-1-butene-1-octene copolymers are preferred, and ethylene-1-butene copolymers are more preferred.

[0074] Examples of α,β-unsaturated carboxylic acids or their anhydrides used in the above-mentioned acid modification include, for example, olefinic unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethylacrylic acid, and crotonic acid; olefinic unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid, maleic acid, monomethyl maleate, and monoethyl maleate; or their anhydrides and esters. These α,β-unsaturated carboxylic acids or their anhydrides and esters can be used alone or in combination of two or more. Maleic anhydride is preferred.

[0075] The acid value of acid-modified ethylene-α-olefin copolymers is typically below 50 mg KOH / g, preferably below 30 mg KOH / g, and particularly preferably below 20 mg KOH / g. If the acid value is too high, the number of reaction sites with the hydroxyl groups in EVOH(B) increases, leading to the formation of highly polymerized compounds during melt mixing, reduced stability during extrusion processing, and a tendency to produce poorly molded products. It should be noted that the lower limit of the acid value is typically 1 mg KOH / g, preferably 2 mg KOH / g. Furthermore, the above acid values ​​are determined based on JIS K0070.

[0076] The melt flow rate (MFR) of the above-mentioned acid-modified ethylene-α-olefin copolymer (230°C, 2160g load) is typically 0.01 to 150 g / 10 min, preferably 0.1 to 50 g / 10 min, more preferably 1 to 25 g / 10 min, and even more preferably 1.5 to 10 g / 10 min.

[0077] In addition, the MFR (230°C, 2160g load) of the above-mentioned maleic anhydride modified ethylene-α-olefin copolymer is generally 0.1 to 150g / 10 minutes, preferably 0.5 to 100g / 10 minutes, more preferably 1 to 50g / 10 minutes, and even more preferably 5 to 35g / 10 minutes.

[0078] If the MFR is outside the above range, it tends to have reduced compatibility with the base polymer and reduced dispersibility when mixed.

[0079] The density of acid-modified ethylene-α-olefin copolymers is typically 0.9 g / cm³. 3 The following is preferred: 0.89 g / cm³ 3 The following is a preferred option: 0.88 g / cm³ 3 The following should be noted: the lower limit of the density of acid-modified ethylene-α-olefin copolymers is typically 0.85 g / cm³. 3 .

[0080] The content of the aforementioned acid-modified ethylene-α-olefin copolymer, relative to 100 parts by weight of the total bio-polyethylene resin (A) and EVOH (B), is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 20 parts by weight, and particularly preferably 1 to 10 parts by weight. If the content of the acid-modified ethylene-α-olefin copolymer is within the above range, it can further suppress the accumulation of bio-polyethylene resin during molding and suppress discoloration and other appearance degradation of the molded article. Furthermore, the aforementioned acid-modified ethylene-α-olefin copolymer can be used alone or in combination of two or more types.

[0081] [Ethylene-unsaturated monocarboxylic acid copolymers, ionomers of ethylene-unsaturated monocarboxylic acid copolymers]

[0082] The above-mentioned ethylene-unsaturated monocarboxylic acid copolymer is obtained by copolymerizing a copolymer containing ethylene and unsaturated monocarboxylic acids.

[0083] Examples of unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, and isobutyl methacrylate esters. These can be used alone or in combination of two or more. Among these, methacrylic acid and methyl methacrylate are preferred, and methyl methacrylate is particularly preferred, from the perspective of suppressing discoloration of the resin composition during molding and preventing the accumulation of material from bio-based polyethylene resins.

[0084] The content of unsaturated monocarboxylic acids in ethylene-unsaturated monocarboxylic acid copolymers is typically 1 to 30% by weight, preferably 5 to 30% by weight. Additionally, the content of ethylene in ethylene-unsaturated monocarboxylic acid copolymers is typically 50 to 99% by weight, preferably 60 to 95% by weight.

[0085] In addition, in addition to ethylene and unsaturated monocarboxylic acids, other polymerizable monomers may be included in the above copolymer components, within a range that does not impair the effect of the invention (e.g., less than 30% by weight of the copolymer components).

[0086] Other polymerizable monomers mentioned above include, for example, unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and phthalic acid; unsaturated dicarboxylic anhydrides such as maleic anhydride, itaconic anhydride, and phthalic anhydride; and vinyl esters such as vinyl acetate and vinyl propionate. These can be used alone or in combination of two or more.

[0087] The melt flow rate (MFR) (190°C, 2160g load) of the above-mentioned ethylene-unsaturated monocarboxylic acid copolymer is typically 0.1 to 100 g / 10 min, preferably 0.5 to 50 g / 10 min, and particularly preferably 1 to 30 g / 10 min. If the MFR is outside the above range, there is a tendency for reduced compatibility with the base polymer and reduced dispersibility during mixing.

[0088] The ionomer of the aforementioned ethylene-unsaturated monocarboxylic acid copolymer refers to the copolymer in which part or all of the acidic portions, such as the carboxyl group, are neutralized by metal ions.

[0089] Metal ions used to neutralize the acidic portions, such as the carboxyl groups, of the aforementioned ethylene-unsaturated monocarboxylic acid copolymers can typically include monovalent metal ions such as lithium, sodium, potassium, rubidium, and cesium; divalent metal ions such as calcium, magnesium, iron, and zinc; and trivalent metal ions such as iron and aluminum. From the perspective of elasticity and flexibility, monovalent metal ions are preferred for neutralizing the acidic portions, and sodium ions are particularly preferred.

[0090] The metal cation content in the ionomer is expected to be typically in the range of 0.4 to 4 mol per 1 kg of ionomer, preferably in the range of 0.6 to 2 mol. Furthermore, the degree of neutralization of the ionomer is 15 to 80%, preferably 20 to 60%, of the acid portion of the ethylene-unsaturated carboxylic acid copolymer neutralized by the aforementioned metal ions.

[0091] In addition, the melting point of the above-mentioned ionomer is usually 70 to 120°C, preferably 80 to 110°C, and particularly preferably 85 to 95°C.

[0092] Furthermore, the melt flow rate (MFR) of the ionomer (190°C, 2160g load) is typically 0.05–100g / 10min, preferably 0.1–50g / 10min, and more preferably 0.1–10g / 10min.

[0093] As the aforementioned ionomer, a monovalent metal ion neutralizer of ethylene-(meth)methyl acrylate copolymer is preferred, and a sodium ion neutralizer of ethylene-methyl methacrylate copolymer is particularly preferred.

[0094] The content of the ionomer of the aforementioned ethylene-unsaturated monocarboxylic acid copolymer or ethylene-unsaturated monocarboxylic acid copolymer relative to 100 parts by weight of the total bio-polyethylene resin (A) and EVOH (B) is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 20 parts by weight, and particularly preferably 1 to 10 parts by weight. If the content of the ionomer of the ethylene-unsaturated monocarboxylic acid copolymer or ethylene-unsaturated monocarboxylic acid copolymer is within the above range, it can further suppress the accumulation of bio-polyethylene resin during molding and suppress discoloration and other appearance degradation of the molded article. Furthermore, the aforementioned ethylene-unsaturated monocarboxylic acid copolymer or ethylene-unsaturated monocarboxylic acid copolymer ionomer can be used alone or in combination of two or more.

[0095] [Ethylene-vinyl alcohol copolymers with 70-90 mol% ethylene structural units]

[0096] The ethylene-vinyl alcohol copolymer with an ethylene structural unit content of 70-90 mol% (hereinafter, sometimes referred to as "EVA saponification") refers to one that is obtained by saponifying the vinyl acetate component of an ethylene-vinyl acetate copolymer with an ethylene content of 70-90 mol%, and differs from the aforementioned EVA in terms of saponification.

[0097] The aforementioned ethylene-vinyl acetate copolymer can be manufactured by any known polymerization method, such as solution polymerization, suspension polymerization, emulsion polymerization, etc., and the saponification of the aforementioned ethylene-vinyl acetate copolymer can also be carried out by known methods. Furthermore, the aforementioned EVA saponified material can be modified as needed.

[0098] The ethylene content of the above-mentioned EVA saponified material is 70-90 mol%, preferably 75-90 mol%, and particularly preferably 80-90 mol%. If the ethylene content is too low, the effects of the present invention (such as suppression of material accumulation) tend to become insufficient.

[0099] Furthermore, the degree of saponification of the aforementioned EVA saponified material is typically 20 mol% or more, more preferably 60 to 100 mol%, and particularly preferably 90 to 100 mol%. That is, if the degree of saponification is too low, the effects of the present invention (such as suppression of material accumulation) sometimes become insufficient.

[0100] In terms of excellent dispersibility and the excellent effects of the present invention, the melt flow rate (MFR) of the above-mentioned EVA saponified material (190°C, 2160g load) is typically 0.5 to 100g / 10min, more preferably 1 to 50g / 10min, and particularly preferably 2 to 30g / 10min.

[0101] The aforementioned EVA saponified compounds, without hindering the spirit of the present invention, can also be modified bodies obtained by chemically combining unsaturated carboxylic acids or their anhydrides through addition reactions, grafting reactions, etc. The amount of modification is preferably, for example, 10 mol% or less. Examples of the aforementioned unsaturated carboxylic acids or their anhydrides include, for example, olefinic unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethylacrylic acid, and crotonic acid; fumaric acid, itaconic acid, citraconic acid, maleic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, and their anhydrides and esters; among which, maleic anhydride is preferred.

[0102] The content of the aforementioned EVA saponified compound relative to 100 parts by weight of the total bio-polyethylene resin (A) and EVOH (B) is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 20 parts by weight, and particularly preferably 1 to 10 parts by weight. If the content of the EVA saponified compound is within the above range, it can further suppress the accumulation of bio-polyethylene resin during molding and suppress discoloration and other appearance degradation of the molded article. Furthermore, the aforementioned EVA saponified compound can be used alone or in combination with two or more EVA saponified compounds having different ethylene content, degree of saponification, molecular weight, MFR, density, modified groups, and their modification amounts.

[0103] [Hydrotalcite type]

[0104] Examples of the aforementioned hydrotalcites include compounds represented by the general formula (1).

[0105] [Chemistry 1]

[0106] M x Al y (OH) 2x+3y-2z (E) z ·aH2O……(1)

[0107] [In the formula, M is Mg, Ca, or Zn; E is CO3 or HPO4; x, y, and z are numbers greater than 0; and a is 0 or a positive number.]

[0108] Specifically, Mg can be cited as a compound represented by the above general formula (1). 4.5 Al2(OH) 13 CO3·3.5H2O, Mg5Al2(OH) 14 CO3·4H2O, Mg6Al2(OH) 16 CO3·4H2O, Mg8Al2(OH) 20 CO3·5H2O, Mg 10 Al2(OH) 22 (CO3)2·4H2O, Mg6Al2(OH) 16 HPO4·4H2O, Ca6Al2(OH)16 CO3·4H2O, Zn6Al6(OH) 16 CO3·4H2O, etc. In addition, it is not limited to the above. For example, it also includes substances that cannot be clearly represented by chemical formulas in which a part of the OH in Mg2Al(OH)9·3H2O is replaced by CO3 or HPO4; furthermore, substances that can also expect equivalent effects after removing crystal water (a = 0). Among them, the compound in which M in the general formula (1) is Mg and E is CO3 shows molding stability and the inhibitory effect of buildup due to phase separation, and is particularly suitable for use.

[0109] In addition, as hydrotalcite-like substances, in addition to the above, for example, compounds represented by the following general formula (2) can also be cited.

[0110] [Chemical formula 2]

[0111] [(M1 2+ ) y1 (M2 2+ ) y2 1-x M x ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​(OOC-COO) 2- ,ClO 4- CH3COO - CO3 2- (OOCHC = CHCOO) 2- [Fe(CN)6] 4- These can be used individually or in combination of two or more, among which CO3... 2- OH - It is useful.

[0114] Moreover, as a compound represented by the above general formula (2), specifically, [Mg] can be cited as an example. 0.75 Zn 0.25 ] 0.67 Al 0.33 (OH)2(CO3) 0.165 ·0.45H2O, [Mg 0.79 Zn 0.21 ] 0.7 Al 0.3 (OH)2(CO3) 0.15 、[Mg 1 / 7 Ca 3 / 7 Zn 3 / 7 ] 0.7 Al 0.3 (OH)2(OOCHC=CHCOO) 0.15 ·0.41H2O, [Mg 6 / 7 Cd 1 / 7 ] 0.7 Al 0.3 (OH)2(CH3COO) 0.3 ·0.34H2O, [Mg 5 / 7Pd 2 / 7 ] 0.7 Al 0.30 (OH)2(CO3) 0.15 ·0.52H2O, [Mg 0.74 Zn 0.26 ] 0.68 Al 0.32 (OH)2(CO3) 0.16 、[Mg 0.56 Zn 0.44 ] 0.68 Al 0.32 (OH)2(CO3) 0.16 ·0.2H2O, [Mg 0.81 Zn 0.19 ] 0.74 Al 0.26 (OH)2(CO3) 0.13 、[Mg 0.75 Zn0.25 ] 0.8 Al 0.20 (OH)2(CO3) 0.10 ·0.16H2O, [Mg 0.71 Zn 0.29 ] 0.7 Al 0.30 (OH)2(NO3) 0.30 、[Mg 0.71 Zn 0.29 ] 0.7 Al 0.30 (OH)2(OOCHC=CHCOO) 0.15 、[Mg 0.14 Ca 0.57 Zn 0.28 ] 0.7 Al 0.30 (OH) 2.3 ·0.25H2O, etc., of which [Mg] is preferred. 0.75 Zn 0.25 ] 0.67 Al 0.33 (OH)2(CO3) 0.165 ·0.45H2O, [Mg 0.79 Zn 0.21 ] 0.7 Al 0.3 (OH)2(CO3) 0.15 、[Mg 6 / 7 Cd 1 / 7 ] 0.7 Al 0.3 (OH)2(CH3COO) 0.3 ·0.34H2O, [Mg 5 / 7 Pd 2 / 7 ] 0.7 Al 0.30 (OH))2(CO3) 0.15 ·0.52H2O, etc.

[0115] For the aforementioned hydrotalcite particles, the average particle size is typically 10 μm or less, more preferably 5 μm or less, and particularly preferably 1 μm or less. That is, if the average particle size is too large, the surface area is small, and therefore, the effects of the present invention may not be fully achieved. It should be noted that the average particle size referred to here is the value measured by laser diffraction / scattering particle size distribution determination method.

[0116] Among the aforementioned hydrotalcites, those with high molding stability, excellent suppression of foreign matter (material buildup) due to phase separation, and high coloring suppression are preferred, especially those with the general formula (1). 16CO3·4H2O.

[0117] The content of the aforementioned hydrotalcite relative to 100 parts by weight of the total bio-polyethylene resin (A) and EVOH (B) is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 20 parts by weight, and particularly preferably 1 to 10 parts by weight. If the content of the hydrotalcite is within the above range, it can further suppress the accumulation of bio-polyethylene resin during molding and suppress discoloration and other appearance degradation of the molded article. Furthermore, the aforementioned hydrotalcite can be used alone or in combination of two or more types.

[0118] When the resin composition of the present invention includes the above-mentioned component (C) in the base polymer [biopolymer polyethylene resin (A) + EVOH (B)], the component (C) preferably contains EVA, acid-modified ethylene-α-olefin copolymer, EVA saponified material, and hydrotalcite, from the perspectives of suppressing discoloration of the molded article, reducing the appearance of the molded article due to the accumulation of biopolymer polyethylene resin during molding, and improving the bulk density when forming granules. Furthermore, it is preferable to use them in combination; examples of preferred combinations include EVA with EVA saponified material and hydrotalcite, and EVA with EVA saponified material. By using them in combination, discoloration of the molded article and the reduction in appearance of the molded article due to the accumulation of biopolymer polyethylene resin during molding can be further suppressed, and the bulk density when forming granules can be further improved.

[0119] [Other ingredients]

[0120] The resin composition of the present invention may contain thermoplastic resins (such as petroleum-derived polyethylene) other than those mentioned in (A) to (C) above, and additives that are usually added to thermoplastic resins, without impairing the effects of the present invention.

[0121] Examples of such additives include plasticizers (e.g., aliphatic polyols such as ethylene glycol, glycerin, and hexanediol), oxygen absorbers, heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (excluding those used as lubricants), antibacterial agents, anti-blocking agents, and fillers (e.g., inorganic fillers). These additives can be used alone or in combination of two or more.

[0122] [Preparation of the resin composition]

[0123] The resin composition of the present invention comprises (A) to (C) as described above, preferably consisting only of (A) to (C) and other components as required. The above-described bio-polyethylene resin (A) and EVOH (B) may also be raw materials that have not been used for molding (non-recycled products), but it is preferable to use recycled materials such as waste materials having a multilayer structure containing layers of bio-polyethylene resin (A) and EVOH (B).

[0124] Alternatively, multilayer structures previously used as various packaging materials may be utilized, depending on the circumstances. Multilayer structures commonly used as packaging materials for food, etc., typically include, in addition to layers formed from bio-based polyethylene resin (A) and EVOH (B), adhesive resin layers and recycled material layers. Therefore, the resin composition of the present invention may include these adhesive resin layers and recycled material layers within a range that does not impair the effects of the present invention (e.g., less than 30% by weight in the resin composition).

[0125] Hereinafter, the method for manufacturing the resin composition of the present invention will be described using a recycled material containing a multilayer structure with a layer formed of bio-polyethylene resin (A) and EVOH (B).

[0126] The scrap, ends, and other unwanted parts (waste) generated during the manufacture of multilayer structures, as well as the recycled materials of multilayer structures that are recycled as waste, are usually crushed and then the particle size is adjusted by sieving or the like as needed, and used as raw materials for the resin composition of the present invention.

[0127] The aforementioned recycled material can be pulverized using a known pulverizer. The apparent density of the pulverized material is typically 0.25–0.85 g / mL, more preferably 0.3–0.7 g / mL, and particularly preferably 0.35–0.6 g / mL. If the apparent density is too low, the dispersion of the bio-polyethylene resin (A) in the resin composition layer becomes poor, and the melt moldability and mechanical properties of the resulting molded article tend to decrease. If the apparent density is too high, the melt moldability of the recycled material layer in the resulting molded article tends to decrease due to poor supply in the extruder. It should be noted that the above apparent density is a value measured according to the "5.3 Apparent Density" test method of JIS K6891.

[0128] The apparent density can be controlled by arbitrarily adjusting the shape of the pulverizing blades, their rotational speed, the pulverizing speed, and the mesh size of the screen used as a sieve. Furthermore, the shape and particle size of the pulverized material can be adjusted using known methods.

[0129] The resin composition of the present invention is manufactured by containing component (C) in a pulverized product (hereinafter referred to as "pulverized product") of a multilayer structure containing bio-polyethylene resin (A) and EVOH (B). From the perspective of productivity, the pulverized product may also contain unrecycled bio-polyethylene resin (A) and unrecycled EVOH (B).

[0130] Examples of known methods for manufacturing the above-mentioned resin composition include dry mixing, melt mixing, solution mixing, and impregnation.

[0131] Examples of the aforementioned dry mixing method include (i) a method of dry mixing the pulverized material with component (C) using a roller or similar device. Alternatively, during the dry mixing process, component (C) can be directly dry mixed, or granules of a thermoplastic resin containing component (C) can be prepared in advance, and these granules can be dry mixed with the pulverized material.

[0132] Examples of the above-mentioned melt mixing method include: (ii) a method of melt mixing the dry mixture described in (i); (iii) a method of adding component (C) to the above-mentioned pulverized product in a molten state and then melt mixing it.

[0133] As an example of the above solution mixing method, one can exemplify (iv) a method of preparing a solution using the above-mentioned pulverized product, mixing component (C) therein, solidifying it, separating the solid and liquid components, and drying it.

[0134] In this invention, the different methods described above can be combined. In terms of productivity, melt mixing is preferred, and method (ii) is particularly preferred.

[0135] It should be noted that, as described above, the resin composition of the present invention is not limited to the use of recycled products with multilayer structures as raw materials; non-recycled bio-based polyethylene resin (A) and EVOH (B) can also be used. When using non-recycled products, the resin composition can be prepared using known general methods, such as dry mixing, melt mixing, solution mixing, etc., in a manner having the formulation of the present invention, and the resin composition prepared in this way is also included in the present invention.

[0136] The water content of the resin composition of the present invention is generally 0.01 to 0.5% by weight, preferably 0.02 to 0.35% by weight, and particularly preferably 0.05 to 0.3% by weight.

[0137] It should be noted that the moisture content of the resin composition in this invention is determined / calculated by the following method.

[0138] Weigh the resin composition before drying (W1) using an electronic balance, dry it in a hot air dryer at 150°C for 5 hours, weigh it after it has cooled naturally in the dryer for 30 minutes (W2), and calculate it according to the following formula.

[0139] Moisture content (wt%) = [(W1-W2) / W1] × 100

[0140] The resin composition of the present invention is prepared in various forms such as granules and powders, and is provided as a molding material for various molded articles. In particular, when provided as a material for melt molding, the effects of the present invention are more effectively obtained, and therefore preferred.

[0141] As the above-mentioned molded articles, a single-layer film obtained by molding using the resin composition of the present invention is representative, and multi-layer structures having layers obtained by molding using the resin composition of the present invention can be provided for practical use.

[0142] [Multi-layer structure]

[0143] The aforementioned multilayer structure includes a layer formed from the resin composition of the present invention. The layer formed from the resin composition of the present invention (hereinafter referred to as the "resin composition layer") can be further endowed with strength or other functions by being laminated with other substrates (hereinafter referred to as "substrate resins") whose main component is a thermoplastic resin other than the resin composition of the present invention.

[0144] Examples of the aforementioned base resins include: polyethylene resins such as linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, and ethylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers; polypropylene resins such as polypropylene and propylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers; polybutene, polypentene, and polycyclic olefin resins (polymers in which at least one of the main chain and side chain has a cyclic olefin structure) (unmodified) polyolefin resins; and these polyolefins... The term "modified olefin resin" broadly refers to polyolefin resins such as unsaturated carboxylic acid-modified polyolefin resins obtained by grafting unsaturated carboxylic acids or their esters, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylate copolymers, polyester resins, polyamide resins (including copolyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, halogenated polyolefins such as polyvinyl chloride and polypropylene chloride, aromatic or aliphatic polyketides, etc.

[0145] In terms of economy and productivity, polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred, and polyethylene resins, polypropylene resins, polycyclic olefin resins, and polyolefin resins modified with unsaturated carboxylic acids are even more preferred.

[0146] When the resin composition layer of the present invention is designated as a (a1, a2, ...) and the substrate resin layer is designated as b (b1, b2, ...), the layer configuration of the multilayer structure can be any combination such as a / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / a / b1 / b2, etc. Furthermore, a reuse layer containing the resin composition of the present invention and the substrate resin can be provided, obtained by remelting and molding end pieces, defective products, etc., generated during the manufacturing process of the multilayer structure. The number of layers in the multilayer structure is typically 2 to 15, preferably 3 to 10. In the above layer configuration, an adhesive resin layer containing an adhesive resin can be sandwiched between each layer as needed.

[0147] As the aforementioned adhesive resin, known substances can be used, and the appropriate choice can be made depending on the type of thermoplastic resin used in the substrate resin layer "b". Representative examples include: modified polyolefin polymers containing carboxyl groups obtained by chemically bonding unsaturated carboxylic acids or their anhydrides to polyolefin resins through addition reactions, grafting reactions, etc. Examples of such modified polyolefin polymers containing carboxyl groups include: maleic anhydride-grafted modified polyethylene, maleic anhydride-grafted modified polypropylene, maleic anhydride-grafted modified ethylene-propylene (block and random) copolymers, maleic anhydride-grafted modified ethylene-ethyl acrylate copolymers, maleic anhydride-grafted modified ethylene-vinyl acetate copolymers, maleic anhydride-modified polycyclic olefin resins, and maleic anhydride-grafted modified polyolefin resins. Furthermore, mixtures of one or more of these can be used.

[0148] In multilayer structures, when an adhesive resin layer is used between the resin composition layer and the substrate resin layer of the present invention, the adhesive resin layer is located on both sides of the resin composition layer. Therefore, it is preferable to use an adhesive resin with excellent hydrophobicity.

[0149] The aforementioned base resin and adhesive resin may contain conventionally known plasticizers, fillers, clays (montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants, nucleating materials, anti-blocking agents, waxes, etc., within a range that does not impede the spirit of the present invention (e.g., 30% or less by weight relative to the total resin, preferably 10% or less by weight).

[0150] The lamination of the resin composition of the present invention with the aforementioned substrate resin (including the case of intercalating an adhesive resin layer) can be performed using known methods. Examples include: a method of melt-extruding and laminating the substrate resin onto a film, sheet, or the like of the resin composition of the present invention; a method of melt-extruding and laminating the resin composition of the present invention onto a substrate resin layer; a method of co-extruding the resin composition and the substrate resin; a method of dry laminating the resin composition layer and the substrate resin layer with a known adhesive such as an organotitanium compound, isocyanate compound, polyester compound, or polyurethane compound; a method of coating a solution of the resin composition onto the substrate resin and then removing the solvent; and so on. From the viewpoints of cost and environment, the method of co-extruding the resin composition and the substrate resin is preferred.

[0151] The aforementioned multi-layered structure is subjected to (heated) stretching treatment as needed. Stretching treatment can be uniaxial or biaxial; in the case of biaxial stretching, it can be simultaneous or sequential stretching. Alternatively, methods with high stretching ratios, such as roller stretching, tenter frame stretching, tubular stretching, stretch blow molding, or vacuum forming, can be used. The stretching temperature is selected from a range of approximately 40–170°C, preferably around 60–160°C, near the melting point of the multi-layered structure. If the stretching temperature is too low, the stretchability becomes poor; if the stretching temperature is too high, it is difficult to maintain a stable stretching state.

[0152] It should be noted that after stretching, heat setting can be performed to impart dimensional stability. Heat setting can be carried out by known means, such as holding the stretched film in a taut state while performing a heat treatment typically at 80–180°C, preferably 100–165°C, for approximately 2–600 seconds. Alternatively, when using a multilayer stretched film obtained from the resin composition of the present invention as a shrink film, to impart heat shrinkability, cooling and fixing of the stretched film by blowing cold air can be performed without the aforementioned heat setting.

[0153] Alternatively, the multi-layer structure of the present invention can be used to obtain cup-shaped or disc-shaped multi-layer containers, depending on the circumstances. In this case, a drawing process is typically used, specifically vacuum forming, pneumatic forming, vacuum pneumatic forming, and plunger-assisted vacuum pneumatic forming. Furthermore, when a tube-shaped or bottle-shaped multi-layer container (laminated structure) is obtained from a multi-layer preform (a hollow tubular preform before blow molding), a blow molding process is used. Specifically, extrusion blow molding (double-head type, mold moving type, preform transfer type, rotary type, accumulator type, horizontal preform type, etc.), cold preform blow molding, injection blow molding, and biaxial stretch blow molding (extrusion cold preform biaxial stretch blow molding, injection cold preform biaxial stretch blow molding, injection molding inline biaxial stretch blow molding, etc.) are examples of such processes. The resulting laminate can be subjected to heat treatment, cooling treatment, calendering treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing treatment, box processing, tube processing, and diversion processing as needed.

[0154] The thickness of the multilayer structure (including stretched ones), and consequently the thickness of the resin composition layer, substrate resin layer, and adhesive resin layer constituting the multilayer structure, varies depending on the layer composition, the type of substrate resin, the type of adhesive resin, the application, the packaging form, and the required physical properties. However, the thickness of the multilayer structure (including stretched ones) is typically 10–5000 μm, preferably 30–3000 μm, and particularly preferably 50–2000 μm. The resin composition layer is typically 1–500 μm, preferably 3–300 μm, and particularly preferably 5–200 μm; the substrate resin layer is typically 5–3000 μm, preferably 10–2000 μm, and particularly preferably 20–1000 μm; and the adhesive resin layer is typically 0.5–250 μm, preferably 1–150 μm, and particularly preferably 3–100 μm.

[0155] Furthermore, regarding the thickness ratio (resin composition layer / substrate resin layer) of the resin composition layer relative to the substrate resin layer in a multilayer structure, when there are multiple layers, the ratio of the thickest layers is typically 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and particularly preferably 10 / 90 to 40 / 60. Additionally, regarding the thickness ratio (resin composition layer / adhesive resin layer) of the resin composition layer relative to the adhesive resin layer in a multilayer structure, when there are multiple layers, the ratio of the thickest layers is typically 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and particularly preferably 50 / 50 to 90 / 10.

[0156] The bags, cups, plates, tubes, bottles, etc. formed from the films, sheets, and stretched films obtained above are useful as packaging materials for various products, including mayonnaise, fillings and other seasonings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals, in addition to general food products.

[0157] Example

[0158] The following examples illustrate the present invention in detail, but the invention is not limited to these examples as long as they do not deviate from its spirit. It should be noted that, unless otherwise specified, "parts" and "%" refer to weight.

[0159] The following ingredients were prepared prior to the examples.

[0160] [Bio-based polyethylene resin (A)]

[0161] (A-1): Plant-derived linear low-density polyethylene [SLH118 (Braskem SA Green PE), MFR 1.0g / 10min (190℃, load 2160g)]

[0162] (A-2): Plant-derived high-density polyethylene [SGM9450F (Braskem SA Green PE), MFR 0.33g / 10 minutes (190℃, 5000g load)]

[0163] [EVOH(B)]

[0164] (B-1): Ethylene-vinyl alcohol copolymer [Ethylene content 29 mol%, MFR 4 g / 10 min (210 °C, load 2160 g)]

[0165] [Ingredient (C)]

[0166] [EVA]

[0167] (C-1): EVA-1 [ULTRATHENE 3B53A (manufactured by Tosoh Corporation), vinyl acetate content 25 mol%, MFR 5.3 g / 10 minutes (190°C, load 2160 g)]

[0168] (C-2): EVA-2 [Evaflex V5961 (manufactured by Dow-Mitsui Polychemicals Co., Ltd.), vinyl acetate content 9 mol%, MFR 1.7 g / 10 min (190 °C, load 2160 g)]

[0169] (C-3): EVA-3 [Evaflex EV170 (manufactured by Dow-Mitsui Polychemicals Co., Ltd.), vinyl acetate content 33 mol%, MFR 1 g / 10 min (190 °C, load 2160 g)]

[0170] [Acid-modified ethylene-α-olefin copolymer]

[0171] (C-4): Maleic anhydride modified ethylene-α-olefin copolymer [acid-modified TOUPHMER MA8510 (Mitsui Chemicals, Inc.), MFR: 5.0 g / 10 min (230 °C, 2160 g load)]

[0172] [Ethylene-unsaturated monocarboxylic acid copolymers, ionomers of ethylene-unsaturated monocarboxylic acid copolymers]

[0173] (C-5): Ethylene-methyl methacrylate copolymer (EMMA) [NUCREL N0903HC (manufactured by Dow-Mitsui Polychemicals Co., Ltd.), methyl methacrylate content 9%, MFR 3g / 10min (190℃, load 2160g), acid value 59mgKOH / g]

[0174] (C-6): Ionomer of ethylene-methyl methacrylate copolymer [HIMIRAN 1707 (manufactured by Dow-Mitsui Polychemicals Co., Ltd.), methyl methacrylate content 9%, MFR 3g / 10min (190℃, load 2160g)]

[0175] [EVA saponification]

[0176] (C-7): Ethylene-vinyl alcohol copolymer [MELTHENE H0051K (manufactured by Tosoh Corporation), ethylene content 89 mol%, saponification degree 99 mol%, MFR 6.5 g / 10 min (190 °C, load 2160 g)]

[0177] [Hydrotalcite type]

[0178] (C-8): Hydrotalcite [ZHT4A (manufactured by Kyowa Chemical Industry Co., Ltd.)]

[0179] [Other ingredients]

[0180] (α-1): Petroleum-derived polyethylene [Novatec UF240 (manufactured by Japan Polyethylene Corporation), MFR 2.1g / 10 minutes (190°C, load 2160g)]

[0181] (α-2): Calcium stearate (manufactured by Nitto Chemical Industry Co., Ltd.)

[0182] (α-3): Hindered phenolic antioxidant [Irganox 1010 (manufactured by BASF Corporation)]

[0183] (α-4): Polyethylene terephthalate [BK-6180C (manufactured by Mitsubishi Chemical Corporation)]

[0184] (α-5): Polybutylene succinate [BioPBS FZ91PM (Made by Mitsubishi Chemical Corporation)]

[0185] (α-6): Polystyrene [G9401 (manufactured by PS Japan Corporation)]

[0186] The above-mentioned components were simultaneously dry-mixed according to Tables 1-4 below, and then fed into a twin-screw mixer at a rate of 25 kg / h using a weight feeder to prepare granular resin compositions of Examples 1-24, Comparative Examples 1-12, and Reference Examples 1 and 2. It should be noted that the mixing conditions are as described below.

[0187] [Mixing Conditions]

[0188] • Twin-screw extruder: 32mm diameter, L / D = 56 (manufactured by Japan Steel Works Co., Ltd.)

[0189] • Extruder set temperature:

[0190] C2 / C3 / C4 / C5 / C6 / C7 / C8 / C9 / C10 / C11 / C12 / C13 / C14 / C15 / C16 / D=90 / 90 / 110 / 150 / 220 / 220 / 220 / 220 / 220 / 220 / 220 / 220 / 220 / 220 / 220 / 220℃

[0191] • Screw speed: 270ppm

[0192] • Discharge rate: 20 kg / hour

[0193] • Cooling of the wire: Water cooling distance 30cm

[0194] • Collection speed: 25m / minute

[0195] • Die head: 4 holes

[0196] [Table 1]

[0197]

[0198] ※1: Content relative to a total of 100 parts by weight of bio-based polyethylene resin (A) and EVOH (B)

[0199] ※2: Mixing ratio in the compounding agent

[0200] [Table 2]

[0201]

[0202] ※1: Content relative to a total of 100 parts by weight of bio-based polyethylene resin (A) and EVOH (B) ※2: Blending ratio in the compounding agent

[0203] [Table 3]

[0204]

[0205] ※1: Content relative to a total of 100 parts by weight of bio-based polyethylene resin (A) and EVOH (B) ※2: Blending ratio in the compounding agent

[0206] [Table 4]

[0207]

[0208] ※1: Content relative to a total of 100 parts by weight of bio-based polyethylene resin (A) and EVOH (B)

[0209] ※2: Mixing ratio in the compounding agent

[0210] ※3: Novatec UF240 (manufactured by Japan Polyethylene Corporation) is used as the petroleum-grade PE.

[0211] The resin compositions of Examples 1-24, Comparative Examples 1-12, and Reference Examples 1 and 2 prepared above were evaluated for accumulation, coloring, and bulk density under the following conditions. These results are shown in Tables 5 and 6 below.

[0212] [Amount of material accumulation]

[0213] When the above resin composition is fed into a twin-screw mixer, the amount of material generated when 5 kg is discharged is sampled and the weight is measured. In addition, the material accumulation improvement rate of each embodiment is calculated by setting the material accumulation amount of the comparative example corresponding to the base polymer [(A)+(B)] of each embodiment to 100 using the following formula.

[0214] Improvement rate (%) = [(M] C -M E ) / M C ]×100

[0215] The above M C M refers to the amount of material generated in a comparative example corresponding to the base polymer [(A)+(B)] of the embodiment. E This refers to the amount of material generated in the embodiment.

[0216] [Coloring Evaluation (YI)]

[0217] The YI (ASTM D1925) of each sample of granular resin composition was determined using a Konica Minolta, Inc. spectrophotometer “CM-3500d” (light source: D65, CM-A120 white calibration plate, CM-A126 petri dish setup, positive reflectance measurement, measurement diameter φ30mm). Approximately 5g of sample was evenly distributed in a petri dish, and the measurement was performed under these conditions to calculate the YI. A higher YI value indicates a more pronounced yellow hue in the resin composition.

[0218] [Bulk density]

[0219] The obtained granules were used to fully fill a 100cc container, and then scraped off from the top without applying pressure. The weight of the granules placed in the container was calculated. The apparent bulk density was calculated by dividing the calculated weight by the volume. In addition, the improvement rate of the bulk density of each embodiment was calculated by setting the bulk density of the comparative example corresponding to the base polymer [(A)+(B)] of each embodiment to 100 using the following formula. If the apparent bulk density is low, it means that there are obstacles in the granules called burrs, making it difficult for the granules to fill densely.

[0220] Improvement rate (%) = [(BD)] C -BD E ) / BD C ]×100

[0221] The above BD C This refers to the bulk density of the comparative example corresponding to the base polymer [(A)+(B)] of the embodiment, BD E This refers to the stacking density of the embodiment.

[0222] [Table 5]

[0223]

[0224] [Table 6]

[0225]

[0226] ※1: As a petroleum-grade PE, Novatec UF240 (manufactured by Japan Corporation) is used.

[0227] The resin composition of the embodiment containing a specified amount of component (C) in bio-polyethylene (A) and EVOH (B) can suppress the amount of material accumulation compared with the resin composition of the corresponding comparative example.

[0228] In addition, the reference example is an example of using polyethylene from a common petroleum source instead of bio-based polyethylene. If we compare Reference Example 1 with Comparative Example 1, in the case of Comparative Example 1 using bio-based polyethylene, the occurrence of material accumulation is particularly noticeable.

[0229] Furthermore, if we compare Reference Example 2 with Example 11, although Example 11 uses bio-based polyethylene, the amount of material accumulation can be suppressed to the same level as Reference Example 2, which uses petroleum-derived polyethylene.

[0230] The above embodiments illustrate specific aspects of the present invention, but these embodiments are merely examples and not intended to be limiting. Various modifications that are obvious to those skilled in the art are within the scope of the invention.

[0231] Industrial availability

[0232] The resin composition of the present invention can prevent discoloration of the molded article and suppress material accumulation even when using bio-polyethylene. Therefore, films, sheets, and stretch films formed from the resin composition of the present invention are useful as materials for various packaging containers.

Claims

1. A resin composition, characterized in that, Contains: a bio-based polyethylene resin (A); an ethylene-vinyl alcohol copolymer with an ethylene content of 20-60 mol% (B); and at least one component selected from the group consisting of ethylene-vinyl acetate copolymer, acid-modified ethylene-α-olefin copolymer, ethylene-unsaturated monocarboxylic acid copolymer, ionomer of ethylene-unsaturated monocarboxylic acid copolymer, ethylene-vinyl alcohol copolymer with an ethylene content of 70-90 mol%, and hydrotalcite (C).

2. The resin composition according to claim 1, characterized in that, The content of the component (C) is 0.1 to 30 parts by weight relative to a total of 100 parts by weight of the bio-polyethylene resin (A) and the ethylene-vinyl alcohol copolymer (B) with an ethylene content of 20 to 60 mol%.

3. The resin composition according to claim 1 or 2, characterized in that, The weight ratio of the bio-polyethylene resin (A) to the ethylene-vinyl alcohol copolymer (B) with an ethylene content of 20-60 mol% [(A) / (B)] is 0.1 / 99.9 to 99.9 / 0.1.

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