Resin composition and method for producing the same, and multilayer structure and recovery aid used in the said production method

Abstract

To provide a resin composition that suppresses fisheye defects in the film while exhibiting superior transparency and a method for producing the same, and a multilayer structure and a recovery aid each of which is used in the production method.SOLUTION: A resin composition includes PO (A), an EVA composition including two or more types of EVA different in ethylene unit content (B), EVOH with an ethylene unit content of 20-55 mol% and a degree of saponification of 95 mol% or more (C), and a fatty acid bivalent metal salt (D), wherein the EVA composition (B) has a degree of saponification of 5 mol% or less and an acid modification level of 0.01 mmol / g or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition containing a polyolefin and an ethylene-vinyl acetate copolymer saponified product, and to a method for producing the same. It also relates to a multilayer structure and a recovery aid used in the production method. [Background technology]

[0002] Conventionally, multilayer structures containing a polyolefin (hereinafter sometimes abbreviated as "PO") layer such as polyethylene or polypropylene and a saponified ethylene-vinyl acetate copolymer (hereinafter sometimes abbreviated as EVOH) layer with excellent barrier properties have been used in various applications such as food packaging containers and fuel containers, taking advantage of their barrier properties. Such multilayer structures are used as various molded products such as films, sheets, cups, trays, and bottles. In recent years, activities to reduce plastic waste have become more active, and in some cases, used containers made of the above-mentioned molded products discharged from general households are collected, melt-molded, and reused as recycled molded products such as films, sheets, cups, trays, and bottles. Such recycling technologies are industrially useful from the standpoint of waste reduction and economic efficiency, and are being put into practical use.

[0003] However, because PO and EVOH have poor compatibility, when laminates containing PO and EVOH layers are melt-molded again and reused as recycled molded products, thermal degradation during melt-molding can cause gelation, or degraded materials can adhere to the screw in the extruder, resulting in appearance defects such as fisheyes in the resulting molded products. In addition, the poor compatibility between PO and EVOH can sometimes cause streaks (striped patterns) to appear on the surface.

[0004] As a solution to these problems, Patent Document 1 describes a resin composition containing PO, EVOH, and an acid-modified olefin-vinyl carboxylate copolymer, which is said to reduce the occurrence of fish eyes, streaks, and grooves in the resulting molded articles.

[0005] Patent Document 2 describes a resin composition for modifying recovered materials containing an ethylene-vinyl acetate copolymer and a saponified ethylene-vinyl acetate copolymer with an ethylene unit content of 70 mol% or more. It states that recycled molded products obtained using this resin composition when recovering and melt-molding a multilayer structure containing a PO layer and an EVOH layer exhibit suppressed discoloration and reduced generation of deposits, resulting in molded products with excellent appearance.

[0006] Patent Document 3 describes a resin composition containing one or more metal compounds selected from olefin-vinyl carboxylate copolymers and / or saponifies thereof, fatty acid metal salts and / or metal oxides, metal hydroxides, metal carbonates, and metal silicates. It states that recycled molded articles obtained using this resin composition when recovering and melt-molding multilayer structures containing PO layers and EVOH layers exhibit excellent long-run moldability, are free from the inclusion of phase-separated foreign matter (deadnetting) of thermoplastic resin and EVOH into the molded article, have excellent delamination resistance between the regrind layer and adjacent layers, and are molded articles without a decrease in mechanical properties such as impact resistance of the regrind layer. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2012 / 060371 [Patent Document 2] International Publication No. 2009 / 041440 [Patent Document 3] Japanese Patent Publication No. 2002-234971 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, with the recent demands for improved quality in recycled molded products containing multilayer structures including PO and EVOH layers, the conventional techniques described above sometimes resulted in insufficient transparency in recycled molded products. To improve this transparency, methods such as adding a large amount of acid-modified compatibilizer or increasing the degree of acid modification of the compatibilizer can be considered to enhance the compatibility between PO and EVOH. However, recycled molded products with improved transparency using such methods tend to have a higher viscosity in the resulting resin composition, making them prone to fisheyes. Therefore, it has been difficult to achieve both fisheye suppression and transparency.

[0009] The present invention was made to solve the above problems, and aims to provide a resin composition that suppresses fisheye in films while also having excellent transparency, a method for producing the same, and a multilayer structure and recovery aid used in such a production method. [Means for solving the problem]

[0010] The above issues are, [1] A resin composition comprising polyolefin (A) (hereinafter sometimes abbreviated as "PO(A)"), an ethylene-vinyl acetate copolymer composition (B) (hereinafter sometimes abbreviated as "EVA composition (B)") containing two or more types of EVA with different ethylene unit content, an ethylene-vinyl acetate copolymer saponified product (C) (hereinafter sometimes abbreviated as "EVOH(C)") having an ethylene unit content of 20 to 55 mol% and a degree of saponification of 95 mol% or more, and a fatty acid divalent metal salt (D), wherein the degree of saponification of the EVA composition (B) is 5 mol% or less and the acid modification amount is 0.01 mmol / g or less; [2] The resin composition of [1], wherein the ethylene unit content of EVA composition (B) is 50 to 90 mol%; [3] The resin composition of [1] or [2], wherein the EVA composition (B) comprises two or more EVAs with different ethylene unit contents, and the difference in ethylene unit content of at least one set of EVAs is 5 to 50 mol%; [4] A resin composition of any of [1] to [3], wherein the mass ratio (B / C) of EVA composition (B) to EVOH (C) is 0.05 to 2; [5] A resin composition of any of [1] to [4], wherein the mass ratio (B / D) of the EVA composition (B) to the fatty acid divalent metal salt (D) is 3 to 100; [6] A resin composition of any of [1] to [5], wherein the mass ratio (C / D) of EVOH (C) to the fatty acid divalent metal salt (D) is 10 to 1000; [7] A resin composition from any of [1] to [6] in which the difference in refractive index (AB) between PO(A) and EVA composition (B) is 0.015 to 0.050, and the difference in refractive index (CB) between EEVOH(C) and EVA composition (B) is 0.001 to 0.080; [8] A resin composition of any of [1] to [7] having a PO(A) content of 80 to 99% by mass, an EVA composition (B) content of 0.10 to 6.0% by mass, an EVOH(C) content of 0.10 to 20% by mass, and a fatty acid divalent metal salt (D) content of 0.005 to 0.50% by mass; [9] A method for producing any of the resin compositions [1] to [8], comprising the step of melt-kneading a multilayer structure having a layer mainly composed of PO(A) and a layer mainly composed of EVOH(C), wherein at least one of the layers constituting the multilayer structure contains at least one selected from the group consisting of EVA composition (B) and fatty acid divalent metal salt (D);

[10] A multilayer structure used in the manufacturing method of [9], comprising a layer mainly composed of PO(A) and a layer mainly composed of EVOH(C), wherein at least one of the layers constituting the multilayer structure is selected from the group consisting of EVA composition (B) and fatty acid divalent metal salt (D);

[11] A method for producing any of the resin compositions [1] to [8], comprising the step of mixing and melt-kneading a multilayer structure having a layer mainly composed of PO(A) and a layer mainly composed of EVOH(C) with a recovery aid, wherein the recovery aid comprises an EVA composition (B) and a fatty acid divalent metal salt (D);

[12] A recovery aid used in the production method of

[11] , comprising an EVA composition (B) and a divalent metal fatty acid salt (D); This is resolved by providing [the solution]. [Effects of the Invention]

[0011] According to the present invention, in a resin composition containing PO and EVOH, a resin composition excellent in transparency while suppressing fish eyes in a film obtained using the resin composition, a production method thereof, a multilayer structure and a recovery aid used in such a production method can be provided.

Embodiments for Carrying Out the Invention

[0012] When a film obtained using the resin composition of the present invention is expressed as a "recycled film", the recycled film may be single-layer or multi-layer. In the examples, mainly single-layer films are used to evaluate transparency and fish eyes, but the same effects can be obtained in multi-layers. In the present specification, "scrap" refers to what is obtained by recovering ends and defective products generated when obtaining a multilayer structure or a molded body. In the present specification, "main component" means more than 50% by mass, preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably consisting essentially of only that component.

[0013] The resin composition of the present invention contains PO (A), an EVA composition (B), EVOH (C), and a fatty acid divalent metal salt (D), and is a resin composition in which the saponification degree of the EVA composition (B) is 5 mol% or less and the amount of acid modification is 0.01 mmol / g or less. By including an EVA composition (B) containing two or more types of EVA having different ethylene unit contents, the transparency of a single-layer film obtained by melt-molding a resin composition containing PO (A) and EVOH (C) tends to be excellent. That is, the transparency of a recycled molded product (such as a recycled film) obtained by recovering and melt-molding a material containing PO (A) and EVOH (C) tends to be excellent. Further, by including a fatty acid divalent metal salt (D), the number of fish eyes in the above-mentioned recycled film tends to decrease. More surprisingly, by including the EVA composition (B) and the fatty acid divalent metal salt (D), the transparency of the above-mentioned recycled film tends to be further excellent.

[0014] (PO(A)) The resin composition of the present invention contains PO(A). PO(A) used in the present invention includes, for example, polyethylene resins such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene; ethylene-based copolymers obtained by copolymerizing ethylene with α-olefins such as 1-butene, 1-hexene, 4-methyl-1-pentene or acrylic esters; polypropylene; propylene-based copolymers obtained by copolymerizing propylene with α-olefins such as ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene; poly(1-butene); poly(4-methyl-1-pentene); ionomer resins and the like. Among them, as PO(A), polyethylene-based resins such as polyethylene and ethylene-based copolymers, or polypropylene-based resins such as polypropylene and polypropylene-based copolymers are preferred, and polyethylene-based resins are more preferred. PO(A) may be used alone or in combination of two or more.

[0015] The refractive index of PO(A) measured by a known prism coupling method is preferably 1.500 or more, more preferably 1.505 or more. Also, the refractive index of PO(A) is preferably 1.540 or less, more preferably 1.530 or less. When the refractive index of PO(A) is within the above range, it is easy to adjust the relationship of the refractive index with the EVA composition (B) and EVOH (C) described later, and the transparency of the obtained resin composition tends to be improved. The refractive index of PO(A) can be measured, for example, by the method described in the examples.

[0016] (EVA composition (B)) The resin composition of the present invention includes an EVA composition (B) containing two or more types of EVA with different ethylene unit content. If only one type of ethylene-vinyl acetate copolymer is used, the compatibility between polyolefin (A) and EVOH (C) decreases, and the transparency of the recovered film tends to deteriorate. The EVA constituting the above EVA composition (B) may consist of two types or three or more types. The preferred embodiment of EVA composition (B) below refers to the embodiment after mixing two or more types of EVA. For example, in an EVA composition (B) blended with 50 parts by mass of EVA having an ethylene unit content of 90 mol% and 50% by mass of EVA having an ethylene unit content of 75 mol%, the ethylene unit content is 83 mol%.

[0017] It is preferable that the EVA composition (B) consists of two or three types of EVA. If at least two types of EVA that make up the EVA composition (B) are designated as EVA(b1) and EVA(b2) in descending order of ethylene unit content (if three types are included, the EVA with the lowest ethylene unit content is designated as EVA(b3)), then the mass ratio of EVA(b1) to EVA(b2) (b1 / B2) is preferably 30 / 70 or more and 90 / 10 or less. Furthermore, the mass ratio of EVA(b1) to the total amount of EVA(b2) and EVA(b3) (b1 / (b2+b3)) is preferably 30 / 70 or more and 90 / 10 or less. The proportion of EVA(b1) in the EVA composition (B) is preferably 30% by mass or more, more preferably 35% by mass or more, and in some cases even more preferably 45% by mass or more. Furthermore, the proportion of EVA(b1) in the EVA composition (B) may be 95% by mass or less, 85% by mass or less, or 75% by mass or less.

[0018] The EVA composition (B) may be saponified, with a degree of saponification of 5 mol% or less. If the degree of saponification of the EVA composition (B) exceeds 5 mol%, the compatibility between PO(A) and EVOH(C) decreases, which may worsen the transparency of the recovered film. A degree of saponification of the EVA composition (B) is more preferably 3 mol% or less, even more preferably 1 mol% or less, and particularly preferably not saponified at all. The degree of saponification of the EVA composition (B) can be measured by NMR. The preferred mode of saponification of the EVA constituting the EVA composition (B) is the same as that of the EVA composition (B).

[0019] The EVA composition (B) may be acid-modified, and the amount of acid modification is 0.01 mmol / g or less. If the amount of acid modification exceeds 0.01 mmol / g, it may become more prone to thickening by reacting with EVOH (C), and the fisheye pattern on the recovered film may increase. Also, if the amount of acid modification exceeds 0.01 mmol / g, it may inhibit the function of the fatty acid divalent metal salt (D), and the fisheye pattern on the recovered film may increase. The amount of acid modification of the EVA composition (B) is more preferably 0.007 mol / g or less, and even more preferably 0.005 mol / g or less. The amount of acid modification of the EVA composition (B) can be measured in accordance with the method described in JIS K2501:2003. The preferred mode of acid modification of the EVA constituting the EVA composition (B) is the same as that of the EVA composition (B).

[0020] EVA composition (B) preferably has an ethylene unit content of 50 to 90 mol%. When the ethylene unit content is within the above range, the compatibility between PO(A) and EVOH(C) improves, and the transparency of the recovered film improves. The ethylene unit content of EVA composition (B) is more preferably 60 mol% or more, and even more preferably 70 mol% or more. The ethylene unit content of EVA composition (B) is more preferably 87 mol% or less, and even more preferably 85 mol% or less. From the viewpoint of improving the transparency of the recovered film, the ethylene unit content of the EVA constituting EVA composition (B) is preferably 20 to 95 mol%. The ethylene unit content of EVA composition (B) and the EVA constituting EVA composition (B) can be measured by NMR.

[0021] When EVA composition (B) contains EVA(b1) and EVA(b2), the ethylene unit content of EVA(b1) is preferably 65 mol% or more, more preferably 75 mol% or more, even more preferably 80 mol% or more, and may be 85 mol% or more. Furthermore, the ethylene unit content of EVA(b1) is preferably 99 mol% or less. Furthermore, the ethylene unit content of EVA(b2) is preferably 30 mol% or more, and may be 50 mol% or more, 60 mol% or more, or 70 mol% or more. Furthermore, the ethylene unit content of EVA(b2) is preferably 95 mol% or less, more preferably 90 mol% or less, and may be 85 mol% or less. When EVA(B) further contains EVA(b3), the ethylene unit content of EVA(b3) is preferably 25 mol% or more, more preferably 30 mol% or more, and even more preferably 35 mol% or more. Furthermore, the ethylene unit content of EVA(b3) is preferably 90 mol% or less, but may also be 70 mol% or less, or 50 mol% or less. When the ethylene unit content of EVA(b1), EVA(b2), and EVA(b3) is within the above range, transparency and suppression of fisheye tend to be better.

[0022] In the EVA composition (B) described above, when the difference in ethylene unit content of each EVA is taken, the difference in ethylene unit content of at least one pair of EVA is preferably 5 to 50 mol%, more preferably 8 to 25 mol%, and even more preferably 10 to 20 mol%. For example, if the EVA composition (B) contains EVA(b1), EVA(b2), and EVA(b3), the difference in ethylene unit content of each EVA means the difference in ethylene unit content between EVA(b1) and EVA(b2), the difference in ethylene unit content between EVA(b1) and EVA(b3), and the difference in ethylene unit content between EVA(b2) and EVA(b3). More specifically, in an EVA composition containing three types of EVA with ethylene unit content of 50 mol%, 70 mol%, and 80 mol% (hereinafter, the ethylene unit content will be denoted as Et50, Et70, and Et80, respectively), the difference in ethylene unit content of each EVA can be calculated as follows. Et70 - Et50 = 20 mol% Et80 - Et50 = 30 mol% Et80 - Et70 = 10 mol%

[0023] The melt flow rate (MFR) of EVA composition (B) at 190°C and under a 2160g load is not particularly limited, but is preferably 0.1 to 30 g / 10 min. The MFR of EVA composition (B) is more preferably 0.5 g / 10 min or more, and even more preferably 1 g / 10 min or more. Furthermore, the MFR of EVA composition (B) is more preferably 10 g / 10 min or less, and even more preferably 5 g / 10 min or less. The preferred embodiment of the MFR of the EVA constituting EVA composition (B) is the same as that of EVA composition (B).

[0024] The EVA components of the EVA composition (B) of the present invention may be modified with one or more unsaturated carboxylic acids or their derivatives. Examples of such unsaturated carboxylic acids or their derivatives include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid; methyl or ethyl esters of the aforementioned acids; maleic anhydride, itaconic anhydride, etc. These may be used individually or in combination of two or more.

[0025] The EVA constituting the EVA composition (B) in the present invention may be crosslinked. A method for crosslinking modification is to add a crosslinking agent to the EVA composition (B). The crosslinking agent can be any agent that can crosslink each component and is not particularly limited, but it is preferable to use an organic peroxide considering reactivity and other factors. The organic peroxide used as a crosslinking agent is not particularly limited as long as it is an organic peroxide, and examples include dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,1-di(t-butylperoxy)cyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexine, 1,3-bis(t-butylperoxyisopropyl)benzene, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,3-bis(t-butylperoxy)diisopropylbenzene, n-butyl-4,4-bis(t-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and t-butylcumyl peroxide. These may be used individually or in mixtures of two or more. Among them, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 1,1-di(t-butylperoxy)cyclohexane are preferred from the viewpoint of reactivity.

[0026] In addition, crosslinking aids such as triallyl isocyanurate and divinylbenzene may be used along with the crosslinking agent as needed. The ethylene-vinyl acetate copolymer composition (B) containing the above crosslinking agent can be crosslinked by heating and kneading. In this case, the kneading temperature is preferably around the melting point of the EVA composition (B) to 300°C.

[0027] Methods for producing the EVA that constitutes the EVA composition (B) of the present invention include known production methods such as high-pressure radical polymerization, solution polymerization, and emulsion polymerization. The EVA that constitutes the EVA composition (B) can be appropriately selected from commercially available products, for example, Ultrasene manufactured by Tosoh Corporation, and Levaprene or Levamelt manufactured by Lanxess.

[0028] There are no particular limitations on the method for producing the EVA composition (B), but from the viewpoint of uniformly dispersing each component, it is preferable to blend the various materials constituting the EVA composition (B) and then melt-knead them in a kneading device. The kneading device is not particularly limited as long as it can uniformly disperse each component, and it can be produced using a resin kneading device that is normally used. Examples of kneading devices include single-screw extruders, twin-screw extruders, multi-screw extruders, Banbury mixers, pressure kneaders, rotary rolls, and internal mixers. Among these, twin-screw extruders are more preferred due to their excellent dispersibility and continuous production capabilities. When kneading with a twin-screw extruder, the screw rotation speed is not particularly limited, but it is preferable to knead at 50 rpm to 3000 rpm, more preferably at 100 rpm to 2000 rpm, and even more preferably at 150 rpm to 1000 rpm.

[0029] In EVA composition (B), the proportion of EVA is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. EVA composition (B) may consist only of EVA. Furthermore, if EVA composition (B) contains a crosslinking agent and, if necessary, a crosslinking aid, the proportion of EVA, crosslinking agent, and, if necessary, crosslinking aid in EVA composition (B) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. EVA composition (B) may consist only of EVA, a crosslinking agent, and, if necessary, a crosslinking aid.

[0030] (EVOH(C)) The resin composition of the present invention contains EVOH(C) having an ethylene unit content of 20 to 55 mol% and a degree of saponification of 95 mol% or more. When the ethylene unit content of EVOH(C) is 20 mol% or more, the compatibility with PO(A) is improved. The ethylene unit content of EVOH(C) is more preferably 25 mol% or more. Furthermore, when the ethylene unit content of EVOH(C) is 55 mol% or less, the gas barrier properties of the multilayer structure that can be used as a raw material for the resin composition of the present invention are improved. The ethylene unit content of EVOH(C) is more preferably 50 mol% or less.

[0031] The degree of saponification of EVOH(C) is 95 mol% or more, more preferably 98 mol% or more, and even more preferably 99 mol% or more, from the viewpoint of gas barrier properties and thermal stability of the multilayer structure that can be used as a raw material for the resin composition of the present invention. The degree of saponification of EVOH(C) may be 100 mol% or less.

[0032] The melt-free flow rate (MFR) of EVOH(C) at 210°C under a 2160g load is preferably 0.1 to 50g / 10min from the viewpoint of melt-free and extrusion-free moldability. The MFR of EVOH(C) is more preferably 0.5g / 10min or more, and even more preferably 1g / 10min or more. Furthermore, the MFR of EVOH(C) is more preferably 20g / 10min or less, and even more preferably 10g / 10min or less.

[0033] EVOH(C) may have units derived from monomers other than ethylene, vinyl acetate and its saponifies, to the extent that the objectives of the present invention are not hindered. When EVOH(C) has the aforementioned other monomer units, the content of each of these other monomer units relative to each of the total structural units of EVOH(C) is preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 10 mol% or less, and particularly preferably 5 mol% or less. Furthermore, when EVOH(C) has the aforementioned other monomer units, the lower limit may be 0.05 mol% or 0.10 mol%. Other monomers include, for example, alkenes such as propylene, butylene, pentene, and hexene; 3-acyloxy-1-propene, 3-acyloxy-1-butene, 4-acyloxy-1-butene, 3,4-diasiloxy-1-butene, 3-acyloxy-4-methyl-1-butene, 4-acyloxy-2-methyl-1-butene, and 4-acyloxy-3-methyl -1-butene, 3,4-diasiloxy-2-methyl-1-butene, 4-acyloxy-1-pentene, 5-acyloxy-1-pentene, 4,5-diasiloxy-1-pentene, 4-acyloxy-1-hexene, 5-acyloxy-1-hexene, 6-acyloxy-1-hexene, 5,6-diasiloxy-1-hexene, 1,3-diacetoxy-2-methyl Examples include alkenes having ester groups such as npropane or their saponides; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, and itaconic acid, or their anhydrides, salts, or mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefin sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, or their salts; vinylsilane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxy-ethoxy)silane, and γ-methacryloxypropylmethoxysilane; alkyl vinyl ethers, vinyl ketones, N-vinylpyrrolidone, vinyl chloride, and vinylidene chloride.

[0034] EVOH(C) may be post-modified by methods such as urethaneization, acetalization, cyanoethylation, or oxyalkyleneization.

[0035] EVOH(C) can be used alone or in combination of two or more types.

[0036] (Divalent metal salts (D) of fatty acids) The resin composition used in the present invention contains a fatty acid divalent metal salt (D). By including a fatty acid divalent metal salt (D), the occurrence of fish eyes caused by the aggregation of degraded materials can be suppressed. Examples of fatty acid divalent metal salts (D) include metal salts of higher fatty acids having 12 or more carbon atoms, such as lauric acid, lauric acid, tridecyl acid, myristic acid, pentadecyl acid, palmitic acid, heptadecyl acid, stearic acid, basic stearic acid, hydroxystearic acid, basic hydroxystearic acid, nonadecanoic acid, oleic acid, behenic acid, montanic acid, and linoleic acid.

[0037] In addition, fatty acid metal salts with 11 or fewer carbon atoms (such as acetates and propionates), and metal salts other than fatty acid metal salts (such as nitrates and sulfates) can also be used.

[0038] Furthermore, the divalent metal salt constituting the fatty acid divalent metal salt (D) may be any metal salt of Group 2 of the periodic table or various divalent transition metal salts, such as magnesium salts, calcium salts, zinc salts, cobalt salts, and manganese salts. Among these, from the viewpoint of productivity and practicality, it is preferable that the divalent metal salt constituting the fatty acid divalent metal salt (D) be at least one selected from the group consisting of magnesium salts, calcium salts, and zinc salts.

[0039] The divalent metal ions constituting the fatty acid divalent metal salt (D) contained in the resin composition of the present invention may exist in a state dissociated from the anion. Alternatively, they may exist in a state coordinated to groups (e.g., carboxyl groups, hydroxyl groups, etc.) of EVOH(C) or other optional components.

[0040] (Adhesive resin (E)) In addition to the PO(A), EVA composition(B), EVOH(C), and fatty acid divalent metal salt(D) described above, it is preferable that the resin composition of the present invention contains an adhesive resin(E). Examples of adhesive resin(E) include modified olefin polymers containing carboxyl groups obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to an olefin polymer by addition reaction or graft reaction. Examples of unsaturated carboxylic acids or their anhydrides include maleic acid, maleic anhydride, fumaric acid, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, citraconic acid, hexahydrophthalic anhydride, etc., with maleic anhydride being particularly preferred. Specifically, one or more mixtures selected from maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-propylene copolymer, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer, etc., are preferred.

[0041] (Resin composition) The PO(A) content in the resin composition of the present invention is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 87% by mass or more, from the viewpoint of transparency of the recovered film and fisheye properties. Furthermore, the PO(A) content is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 96% by mass or less. When the PO(A) content is 99% by mass or less, the cost tends to be reduced when the resin composition of the present invention is manufactured by recovering a multilayer structure containing an EVOH layer.

[0042] From the viewpoint of transparency of the recovered film, the content of EVA composition (B) in the resin composition of the present invention is preferably 0.10% by mass or more, more preferably 0.25% by mass or more, and even more preferably 0.5% by mass or more. Furthermore, from the viewpoint of suppressing fisheye, the content of EVA composition (B) in the resin composition of the present invention is preferably 6.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less.

[0043] The EVOH(C) content in the resin composition of the present invention is preferably 0.10% by mass or more, more preferably 0.5% by mass or more, and even more preferably 2.0% by mass or more. When the EVOH(C) content is 0.10% by mass or more, the cost tends to be reduced when the resin composition of the present invention is manufactured by recovering a multilayer structure containing an EVOH layer. Furthermore, from the viewpoint of transparency of the recovered film and fisheye, the EVOH(C) content in the resin composition of the present invention is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 6.0% by mass or less.

[0044] The content of the fatty acid divalent metal salt (D) in the resin composition of the present invention is preferably 0.005% by mass or more, more preferably 0.015% by mass or more, and even more preferably 0.020% by mass or more. Furthermore, the content of the fatty acid divalent metal salt (D) is preferably 1.2% by mass or less, more preferably 0.50% by mass or less, even more preferably 0.30% by mass or less, even more preferably 0.25% by mass or less, and particularly preferably 0.15% by mass or less. When the content of the fatty acid divalent metal salt (D) is within the above range, the fisheye pattern on the recovered film tends to be suppressed.

[0045] In the resin composition of the present invention, the mass ratio (B / C) of EVA composition (B) to EVOH (C) is preferably 0.05 to 2. When the mass ratio (B / C) is 0.05 or higher, the transparency of the recovered film tends to improve. A mass ratio (B / C) of 0.1 or higher is more preferable, and 0.2 or higher is even preferable. Furthermore, when the mass ratio (B / C) is 2 or lower, the fisheye pattern of the resulting recovered film tends to be suppressed. A mass ratio (B / C) of 1.5 or lower is more preferable, and 1.0 or lower is even preferable.

[0046] In the resin composition of the present invention, the mass ratio (B / D) of the EVA composition (B) to the fatty acid divalent metal salt (D) is preferably 3 to 100. When the mass ratio (B / D) is 3 or higher, transparency tends to improve. A mass ratio (B / D) of 5 or higher is more preferable, and 10 or higher is even more preferable. Furthermore, when the mass ratio (B / D) is 100 or lower, fisheye formation in the recovered film tends to be suppressed. A mass ratio (B / D) of 75 or lower is more preferable, and 50 or lower is even more preferable.

[0047] In the resin composition of the present invention, the mass ratio (C / D) of EVOH(C) to the fatty acid divalent metal salt (D) is preferably 10 to 1000. When the mass ratio (C / D) is 10 or more, thermal degradation of EVOH(C) during melt kneading is suppressed, and fisheye formation in the recovered film tends to be suppressed. A mass ratio (C / D) of 20 or more is more preferable, and 50 or more is even preferable. Furthermore, when the mass ratio (C / D) is 1000 or less, fisheye formation tends to be suppressed. A C / D of 500 or less is more preferable, and 200 or less is even preferable.

[0048] In the resin composition of the present invention, it is preferable that the difference in refractive index (AB) between PO(A) and EVA composition (B) is 0.015 to 0.050, and the difference in refractive index (CB) between EVOH(C) and EVA composition (B) is 0.001 to 0.080. When the refractive index differences of each component are within the above ranges, the transparency of the recovered film is improved. Although the reason is not clear, it is presumed that the presence of EVA composition (B) satisfying the above refractive index difference at the interface between the matrix of PO(A) and the domains of EVOH(C) causes the apparent refractive index of EVOH(C) to approach that of PO(A), thereby suppressing light scattering in the recovered film and, as a result, improving the transparency of the recovered film. The difference in refractive index (AB) between PO(A) and EVA composition (B) is more preferably 0.020 to 0.045, and even more preferably 0.025 to 0.040. Furthermore, the difference in refractive index (CB) between EVOH (C) and the EVA composition (B) is more preferably 0.010 to 0.070, and even more preferably 0.030 to 0.060.

[0049] (Other compounds) The resin composition of the present invention may also contain other compounds besides PO(A), EVA composition(B), EVOH(C), aliphatic divalent metal salt(D), and adhesive resin(E), to the extent that they do not impair the effects of the present invention. Examples of the other compounds include resins other than PO(A), EVA composition(B), EVOH(C), and adhesive resin(E), carboxylic acid compounds, phosphoric acid compounds, boron compounds, metal salts (alkali metal salts, alkaline earth metal salts other than fatty acid divalent metal salt(D)), antioxidants, ultraviolet absorbers, plasticizers, lubricants, fillers, and antistatic agents. The content of the other compounds in the resin composition of the present invention is usually 5% by mass or less, preferably 2% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less. When the resin composition of the present invention contains carboxylic acid compounds, phosphoric acid compounds, boric acid compounds, or metal salts, it is preferable that these compounds are pre-mixed with EVOH(C).

[0050] Examples of resins other than PO(A), EVA composition(B), EVOH(C), and adhesive resin(E) include polyamide, polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, epoxy resin, acrylic resin, urethane resin, polyester resin, and the like.

[0051] The carboxylic acid compound may be a monocarboxylic acid, a polycarboxylic acid, or a combination thereof. The carboxylic acid compound may also be an ion, and such carboxylic acid ions may form salts with metal ions. The content of carboxylic acid and carboxylic acid ions is preferably 0.05 to 20 ppm. Suitable carboxylic acid compounds include, for example, aliphatic carboxylic acids such as acetic acid and stearic acid. When the resin composition of the present invention contains a carboxylic acid compound, discoloration during melt molding tends to be prevented.

[0052] The phosphate compound is not particularly limited, and various acids such as phosphoric acid and phosphorous acid, or their salts, can be used. The phosphate may be included in the form of a first phosphate, second phosphate, or third phosphate, but the first phosphate is preferred. The cation species is also not particularly limited, but alkali metal salts are preferred. Among these, sodium dihydrogen phosphate and potassium dihydrogen phosphate are preferred. When the resin composition of the present invention contains a phosphate compound, the content of the phosphate compound is preferably 0.05 to 25 ppm in terms of phosphate root. When the content of the phosphate compound is 0.05 ppm or more, the color resistance during melt molding tends to be good. On the other hand, when the content of the phosphate compound is 25 ppm or less, the melt moldability tends to be good.

[0053] The boron compound is not particularly limited and includes boric acids, boric acid esters, borate salts, and boron hydride compounds. Specifically, examples of boric acids include orthoboric acid, metaboric acid, and tetraboric acid; examples of boric acid esters include triethyl borate and trimethyl borate; and examples of borate salts include alkali metal salts, alkaline earth metal salts, and borax of the aforementioned boric acids. Among these compounds, orthoboric acid (hereinafter sometimes simply referred to as boric acid) is preferred. When the resin composition of the present invention contains a boron compound, the content of the boron compound is preferably 1 to 100 ppm in terms of elemental boron. When the content of the boron compound is 1 ppm or more, torque fluctuations during heating and melting tend to be suppressed. On the other hand, when the content of the boron compound is 100 ppm or less, moldability tends to be maintained well.

[0054] The cation species of the alkali metal salt is not particularly limited, but sodium or potassium salts are preferred. The anionic species of the alkali metal salt is also not particularly limited. It can be added as a carboxylate, carbonate, bicarbonate, phosphate, hydrogen phosphate, borate, hydroxide, etc. When the resin composition of the present invention contains an alkali metal salt, the alkali metal salt content is preferably 0.5 to 25 ppm in terms of metal element. When the alkali metal salt content is 0.5 ppm or more, interlayer adhesion tends to be good. On the other hand, when the alkali metal salt content is 25 ppm or less, melt stability tends to be excellent.

[0055] The cation species of the alkaline earth metal salt other than the fatty acid divalent metal salt (D) is not particularly limited, but magnesium salts or calcium salts are preferred. The anionic species of the alkaline earth metal salt is also not particularly limited. It can be added as a carbonate, bicarbonate, phosphate, hydrogen phosphate, borate, hydroxide, etc. The alkaline earth metal salt content is preferably 0.5 to 25 ppm. When the resin composition of the present invention contains an alkaline earth metal salt, it tends to suppress deterioration and the generation of deterioration products such as gel when the molded body is repeatedly melt-molded.

[0056] Antioxidants: 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4'-thiobis(6-t-butylphenol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, 4,4'-thiobis(6-t-butylphenol), etc.

[0057] UV absorbers: Ethylene-2-cyano-3,3'-diphenyl acrylate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, etc.

[0058] Plasticizers: Dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphate esters, etc.

[0059] Lubricants: Stearamide, oleamide, erucamide, behenamide, ethylenebis-stearamide, methylol-stearamide, N-oleyl palmitamide, N-stearyl erucamide, liquid paraffin, natural paraffin, synthetic paraffin, polyolefin wax, stearyl alcohol, lauryl alcohol, stearic acid, lauric acid, myristic acid, behenic acid, montanic acid, stearyl stearate, stearyl laurate, calcium stearate, magnesium stearate, zinc stearate, lead stearate, etc.

[0060] Fillers: Fiberglass, asbestos, ballastite, calcium silicate, etc.

[0061] Antistatic agents: Glycerin mono fatty acid ester, fatty acid diethanolamide, alkyldiethanolamine, alkyl sulfonate, alkylbenzene sulfonate, alkyltrimethylammonium salt, alkylbenzyldimethylammonium salt, alkylbetaine, alkylimidazolium betaine, etc.

[0062] In the resin composition of the present invention, the proportion of PO(A), EVA composition(B), and EVOH(C) among the total resins is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more. It may be substantially composed of only PO(A), EVA composition(B), and EVOH(C), or it may be substantially composed of only PO(A), EVA composition(B), and EVOH(C). If the resin composition of the present invention contains an adhesive resin(E), the proportion of PO(A), EVA composition(B), EVOH(C), and adhesive resin(E) among the total resins in the resin composition of the present invention is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more. It may be substantially composed of only PO(A), EVA composition(B), EVOH(C), and adhesive resin(E), or it may be substantially composed of only PO(A), EVA composition(B), EVOH(C), and adhesive resin(E). Furthermore, in the resin composition of the present invention, the proportion of PO(A), EVA composition(B), EVOH(C), and fatty acid divalent metal salt(D) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, and may be substantially composed only of PO(A), EVA composition(B), EVOH(C), and fatty acid divalent metal salt(D). If the resin composition of the present invention contains an adhesive resin(E), the proportion of PO(A), EVA composition(B), EVOH(C), fatty acid divalent metal salt(D), and adhesive resin(E) in the resin composition of the present invention is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, and may be substantially composed only of PO(A), EVA composition(B), EVOH(C), fatty acid divalent metal salt(D), and adhesive resin(E).

[0063] (Method for manufacturing resin compositions) The method for producing the resin composition of the present invention is not particularly limited, but for example, a method of dry blending and melt-kneading PO(A), EVA composition(B), EVOH(C), and a divalent metal fatty acid salt(D); a method of pre-dry-blending at least one selected from the group consisting of PO(A), EVA composition(B), EVOH(C), and a divalent metal fatty acid salt(D), and then blending and melt-kneading other components; a method of pre-dry-blending at least one selected from the group consisting of PO(A), EVA composition(B), EVOH(C), and a divalent metal fatty acid salt(D) Examples of the methods include: a method in which the seeds are melt-kneaded in advance, and then other components are added and melt-kneaded; a method in which a multilayer structure having a layer mainly composed of PO(A) and a layer mainly composed of EVOH(C) is melt-kneaded with a recovery aid containing an EVA composition (B) and a fatty acid divalent metal salt (D); and a method in which a multilayer structure having a layer mainly composed of PO(A) and a layer mainly composed of EVOH(C) is melt-kneaded with a multilayer structure in which at least one layer of the multilayer structure contains an EVA composition (B) and a fatty acid divalent metal salt (D). Furthermore, if the resin composition of the present invention contains the other compounds, the other compounds may be mixed in the dry-blending process described above, included in the layers constituting the multilayer structure, or added as a recovery aid during melt-kneading.

[0064] In particular, a method comprising the step of melt-kneading a multilayer structure having a layer mainly composed of PO(A) and a layer mainly composed of EVOH(C), wherein at least one of the layers constituting the multilayer structure contains at least one selected from the group consisting of EVA composition (B) and fatty acid divalent metal salt (D), is preferred from the viewpoint of practicality and economy. Furthermore, from the viewpoint of maintaining the performance of the multilayer structure, it is even more preferable that the layer mainly composed of PO(A) contains at least one selected from the group consisting of EVA composition (B) and fatty acid divalent metal salt (D). The method of incorporating at least one selected from the group consisting of EVA composition (B) and fatty acid divalent metal salt (D) into at least one of the layers constituting the multilayer structure is not particularly limited, but for example, EVA composition (B) and fatty acid divalent metal salt (D) may be incorporated into separate layers, or they may be incorporated into the same layer. Alternatively, the resin that forms the raw material for the layers constituting the multilayer structure may be dry-blended with a recovery aid or its components as described later and used directly to form a film, or the resin that forms the raw material for the layers constituting the multilayer structure may be dry-blended with a recovery aid or its components as described later, melt-kneaded to produce pellets, and then used to form a film.

[0065] Furthermore, in the production of the resin composition of the present invention, a method is also preferred from the viewpoint of practicality and economy in which a multilayer structure having a layer mainly composed of PO(A) and a layer mainly composed of EVOH(C) is mixed with a recovery aid and melt-kneaded, wherein the recovery aid includes an EVA composition (B) and a fatty acid divalent metal salt (D). In this case, it is preferable to use the multilayer structure as scrap crushed by a known method. As the recovery aid added to the crushed scrap, for example, the EVA composition (B) and the fatty acid divalent metal salt (D) may be blended separately, but it is preferable to dry-blend and melt-knead a pellet-shaped recovery aid containing the EVA composition (B) and the fatty acid divalent metal salt (D) beforehand, and then dry-blend and melt-knead it. As the scrap, scrap obtained from one molded product may be used, or related scrap obtained from two or more molded products may be mixed and used.

[0066] The recovery aid of the present invention comprises an EVA composition (B) and a fatty acid divalent metal salt (D). The inclusion of the EVA composition (B) improves recovery efficiency and results in good transparency of the recycled molded product obtained after recovery. Furthermore, the inclusion of the fatty acid divalent metal salt (D) tends to suppress the occurrence of fish eyes in the recycled molded product obtained after recovery. Preferred embodiments of the EVA composition (B) and fatty acid divalent metal salt (D) contained in this recovery aid are the same as those contained in the resin composition described above. The content of the EVA composition (B) in the recovery aid of the present invention is preferably 20% by mass or more, more preferably 60% by mass or more, even more preferably 80% by mass or more, may be 99% by mass or more, and may be 100% by mass or less. Furthermore, the content of the fatty acid divalent metal salt (D) in the recovery aid of the present invention is preferably 0.1 to 25% by mass, more preferably 0.5 to 10% by mass. In the recovery aid of the present invention, the proportion of the EVA composition (B) and the fatty acid divalent metal salt (D) is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 97% by mass or more, and may be 99% by mass or more. The recovery aid of the present invention may consist substantially of only the EVA composition (B) and the fatty acid divalent metal salt (D).

[0067] Furthermore, the recovery aid of the present invention may contain PO(A) from the viewpoint of feedability during the manufacture of the recovery aid. When the recovery aid of the present invention contains PO(A), the content of PO(A) in the recovery aid of the present invention is preferably 20% to 90% by mass, and more preferably 30% to 80% by mass. When the recovery aid of the present invention contains PO(A), the content of EVA composition (B) in the recovery aid of the present invention is preferably 10% to 80% by mass, and more preferably 20% to 70% by mass. When the recovery aid of the present invention contains PO(A), the content of fatty acid divalent metal salt (D) in the recovery aid of the present invention is preferably 0.1% to 15% by mass, and more preferably 1% to 10% by mass. When the recovery aid of the present invention contains PO(A), the proportion of PO(A), EVA composition (B), and fatty acid divalent metal salt (D) in the recovery aid of the present invention is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 97% by mass or more, and may be 99% by mass or more. The recovery aid of the present invention may consist substantially only of PO(A), EVA composition (B), and fatty acid divalent metal salt (D). The PO(A) contained in the recovery aid may be the same as or different from the PO(A) that constitutes the multilayer structure that can be used as a raw material for the resin composition of the present invention.

[0068] The recovery aid of the present invention may contain other compounds besides PO(A), EVA composition(B), and fatty acid divalent metal salt(D), as long as they do not inhibit the effects of the present invention. Examples of the other compounds include other compounds that may be contained in the resin composition described above, and the recovery aid may also contain EVOH(C). The content of the other compounds in the recovery aid of the present invention is usually 50% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 7% by mass or less, and particularly preferably 3% by mass or less.

[0069] From the viewpoint of compatibility, when the recovery aid of the present invention contains PO(A), it is preferable that the PO(A) contained in the recovery aid and the PO(A) contained in the recovered multilayer structure are of the same type. For example, if the PO(A) contained in the recovered multilayer structure is polypropylene, it is preferable that the PO(A) contained in the recovery aid is also polypropylene, and if the PO(A) contained in the recovered multilayer structure is polyethylene, it is preferable that the PO(A) contained in the recovery aid is also polyethylene.

[0070] If the recovery aid of the present invention contains compounds other than the EVA composition (B) and the fatty acid divalent metal salt (D), it is preferable to pre-melt-knead the EVA composition (B) and the fatty acid divalent metal salt (D) with the other compounds to create a recovery aid containing all of them, and then add it to the recovered material. Such a recovery aid is preferably incorporated into the recovered material in pellet form. It is preferable to crush the recovered material to an appropriate size, and it is preferable to mix the pellet-shaped recovery aid with the crushed recovered material.

[0071] While unused resin may be used as the raw material for the resin composition of the present invention, it is preferable from the viewpoint of reducing waste and costs to use recovered multilayer structures as described above as at least a part of the raw material. The proportion of the recovered material in the raw material of the resin composition of the present invention is preferably 50% by mass or more. In addition, as long as it does not hinder the effects of the present invention, packaging materials (multilayer structures) consumed in the market may be used as the raw material for the recovered material. In that case, a process is generally employed in which the packaging material is cut, separated and washed as necessary, and then melt-kneaded using an extruder.

[0072] The multilayer structure used as a raw material for the resin composition of the present invention is not particularly limited, and examples include multilayer structures having the following layer configurations. In the following examples, the PO(A) layer is denoted as "A", the EVOH(C) layer as "C", the adhesive resin(E) layer as "E", the resin composition layer of the present invention as "F", and direct lamination as " / ". 3-layer A / E / C, A / C / A 5 layers A / E / C / E / A, A / E / C / E / F 6 layers A / E / C / E / F / A, F / A / E / C / E / A, A / F / E / C / E / F, F / A / E / C / E / F 7 layers A / F / E / C / E / F / A, A / F / E / C / E / A / F, F / A / E / C / E / A / F

[0073] It is preferable that the multilayer structure has a resin composition layer of the present invention from the viewpoint of reducing waste and costs. Furthermore, it is preferable that the EVOH(C) layer and the adhesive resin(E) layer are in contact from the viewpoint of improving interlayer adhesion.

[0074] The overall thickness of the multilayer structure can be set appropriately depending on the application. A suitable overall thickness is 20 to 2000 μm. A multilayer structure with high rigidity can be obtained with an overall thickness of 20 μm or more. A more suitable overall thickness is 50 μm or more. On the other hand, a flexible multilayer structure can be obtained with an overall thickness of 2000 μm or less. A more suitable overall thickness is 1000 μm or less.

[0075] The method for manufacturing the multilayer structure is not particularly limited. For example, molding methods commonly used in the field of polypropylene (PO) can be used, such as extrusion molding, blow molding, injection molding, and thermoforming. Among these, co-extrusion molding and co-injection molding are preferred, with co-extrusion molding being more preferred.

[0076] The multilayer structure of the present invention is environmentally friendly and cost-effective because it comprises layers mainly composed of the resin composition of the present invention. Furthermore, it is preferable that the multilayer structure of the present invention further comprises a PO(A) layer, an EVOH(C) layer, and an adhesive resin (E) layer. Suitable layer configurations and manufacturing methods for the multilayer structure of the present invention are described above as examples of multilayer structures used as raw materials that have layers of the resin composition of the present invention. In addition, the multilayer structure of the present invention may have other resin layers other than the PO(A) layer, EVOH(C) layer, and adhesive resin (E) layer, as long as they do not impair the effects of the present invention. Examples of the other resin layers include ethylene-vinyl acetate copolymer layers, polyester layers such as polyethylene terephthalate, polyester elastomer layers, polyamide layers such as nylon-6 and nylon-66, polystyrene layers, polyvinyl chloride layers, polyvinylidene chloride layers, acrylic resin layers, vinyl ester resin layers, polyurethane layers, and polycarbonate layers.

[0077] The resin composition of the present invention can be molded into any molded product such as films, sheets, tubes, bottles, and cups using well-known melt extrusion machines, compression molders, transfer molders, injection molders, blow molders, thermoforming machines, rotational molders, dip molders, etc. The extrusion temperature for molding is appropriately selected depending on the type of PO(A) constituting the resin composition of the present invention, the MFR of PO(A) and EVOH(C), the composition ratio of PO(A) and EVOH(C), or the type of molding machine, but is often in the range of 130 to 350°C.

[0078] Molded articles obtained by molding the resin composition of the present invention can be used as food packaging containers, beverage containers, cosmetic containers, fuel containers, pharmaceutical containers, and the like. [Examples]

[0079] The present invention will be described in more detail below using examples, but the present invention is not limited in any way by these examples.

[0080] <Evaluation Method> (1) Determination of the amount of acid denaturation For the EVA compositions (B), EVA (b1), EVA (b2), or EVA (b3) used in the examples and comparative examples, the acid value was measured according to JIS K2501:2003, and the amount of acid denaturation (mmol / g) was calculated from the acid value. The results are shown in Table 1.

[0081] (2) Measurement of refractive index The refractive index of PO(A), EVA composition(B), and EVOH(C) used in the examples and comparative examples was measured using a known prism coupling method. Specifically, using a tabletop hot press (Shinto Metal Industries Co., Ltd.), 10 g of each resin was placed in the circular opening of a 100 μm thick iron plate spacer placed on a Teflon® sheet, sandwiched with another Teflon® sheet, and hot-pressed at 200°C for 120 seconds to obtain a 100 μm thick pressed film. Using the obtained pressed film, the refractive index in the thickness direction with respect to a 532 nm wavelength laser light was measured using a Metricon "Prism Coupler Model 2010 / M".

[0082] (3) Evaluation of Transparency A 10cm x 10cm square sample was cut from the center of the recovered single-layer film (I) obtained in the examples and comparative examples. Subsequently, the haze of the cut-out sample was measured using a Boick integrating sphere type light transmittance / total light reflectance meter (HR-100 model, manufactured by Murakami Color Technology Laboratory) in accordance with JIS K7375.

[0083] (4) Evaluation of Fisheye When preparing the recovered single-layer film (II) obtained in the examples and comparative examples, a defect detector (FE Counter manufactured by Frontier Systems Co., Ltd.) was used to detect defects in a width of 0.08 m x length of 1 m (0.08 m 2 The number of fish eyes inside was counted. The evaluation criteria were as follows: A: Fish Eye count is 500 or less B: Number of Fish Eyes: 501 or more, up to 1500 C: Fish Eye count: 1501 or more

[0084] <Materials Used> ·PO(A) A1: LDPE “Novatec (trademark) LJ400” manufactured by Nippon Polyethylene Co., Ltd. ·EVA Composition (B) (EVA(b1)) b1-1: EVA manufactured by a known method, ethylene unit content 90 mol%, saponification degree 0 mol%, acid modification amount 0.005 mmol / g, density 0.95 g / cm 3 b1-2: EVA manufactured by a known method, ethylene unit content 93 mol%, saponification degree 0 mol%, acid modification amount 0.005 mmol / g, density 0.94 g / cm 3 b1-3: EVA manufactured by a known method, ethylene unit content 87 mol%, saponification degree 0 mol%, acid modification amount 0.004 mmol / g, density 0.95 g / cm 3 b1-4: Saponified EVA manufactured by a known method, ethylene unit content 89 mol%, saponification degree 97.1 mol%, acid modification amount 0.012 mmol / g, density 0.97 g / cm 3 [[ID=​​​​​​​​​​​​​b2-4: EVA manufactured by known methods, ethylene unit content 70 mol%, degree of saponification 0 mol%, acid modification amount 0.15 mmol / g, density 0.95 g / cm³ 3 b2-5: EVA manufactured by known methods, ethylene unit content 90 mol%, degree of saponification 0 mol%, acid modification amount 0.005 mmol / g, density 0.95 g / cm³ 3 (EVA(b3)) b3-1: EVA manufactured by known methods, ethylene unit content 81 mol%, degree of saponification 0 mol%, acid modification amount 0.003 mmol / g, density 0.97 g / cm³ 3 b3-2: EVA manufactured by known methods, ethylene unit content 43 mol%, degree of saponification 0 mol%, acid modification amount 0.003 mmol / g, density 1.11 g / cm³ 3 ·EVOH(C) C1: "EVAL (trademark) F171B" EVOH, manufactured by Kuraray Co., Ltd., ethylene unit content 32 mol%, saponification degree 99 mol or higher. C2: "EVAL (trademark) L171B" EVOH, manufactured by Kuraray Co., Ltd., ethylene unit content 27 mol%, saponification degree 99 mol or higher. C3: "EVAL (trademark) G156B" EVOH, manufactured by Kuraray Co., Ltd., ethylene unit content 48 mol%, saponification degree 99 mol or higher. • Divalent metal salts of fatty acids (D) StMg: Magnesium stearate StCa: Calcium stearate StZn: Zinc stearate ·Adhesive resin (E) E1: "Admer (trademark) NF518" Maleic anhydride-modified polyethylene, manufactured by Mitsui Chemicals, Inc., density 0.91 g / cm³ 3

[0085] <Examples> Example 1 (Preparation of EVA composition (B1)) 50 parts by mass of EVA(b1-1) and 50 parts by mass of EVA(b2-1) were dry blended and melt-molded using a twin-screw extruder (Toyo Seiki Mfg. Co., Ltd. twin-screw segment extruder "2D30W2" (D(mm)=25, L / D=30, screw: fully meshed in the same direction)) to obtain EVA composition (B1) pellets.

[0086] (Fabrication of multilayer structures) Using a co-extrusion multilayer casting apparatus, the PO layer consists of low-density polyethylene (LDPE; "Novatec® LJ400" manufactured by Nippon Polyethylene Co., Ltd.), the barrier layer consists of EVOH(C) ("Eval® F171B" manufactured by Kuraray Co., Ltd.), and the adhesive layer consists of maleic anhydride-modified polyethylene ("Admer® NF518" manufactured by Mitsui Chemicals, Inc., density 0.91 g / cm³). 3 A multilayer structure (a 5-layer co-extruded multilayer cast film) was fabricated, consisting of the following layers: LDPE layer / maleic anhydride-modified polyethylene layer / EVOH layer / maleic anhydride-modified polyethylene layer / LDPE layer = 40 μm / 5 μm / 10 μm / 5 μm / 40 μm. The film fabrication conditions are as follows. Co-extrusion conditions PO layer extrusion temperature: Feed unit / Compression unit / Measuring unit / Die = 180 / 220 / 220 / 220℃ Barrier layer extrusion temperature: Feed unit / Compression unit / Measuring unit / Die = 180 / 220 / 220 / 220℃ Extrusion temperature of the adhesive layer: Feed unit / Compression unit / Measuring unit / Die = 180 / 220 / 220 / 220℃ Extruder: • PO layer 32φ extruder GT-32-A type (manufactured by Plastics Engineering Research Institute Co., Ltd.) • Barrier layer 20φ extruder, laboratory type ME CO-EXT (manufactured by Toyo Seiki Seisakusho Co., Ltd.) • Adhesive layer: 25φ extruder P25-18-AC type (manufactured by Osaka Seiki Kogyo Co., Ltd.) T-die: 300mm width, 3 types, 5 layers (manufactured by Plastics Engineering Laboratory Co., Ltd.) Cooling roll temperature: 80℃ Pickup speed: 3.0m / min

[0087] (Preparation of single-layer film) Except for changing the resin used in each extruder to low-density polyethylene (LDPE; "Novatec® LJ400" manufactured by Nippon Polyethylene Co., Ltd.), the film was fabricated in the same manner as the above-mentioned multilayer structure, and a 100 μm thick LDPE single-layer film was obtained.

[0088] (Crush) The multilayer structure obtained above was crushed using an 8mm diameter mesh pulverizer to produce a recovered multilayer structure. Similarly, the single-layer film obtained above was crushed using an 8mm diameter mesh pulverizer to produce a recovered single-layer film.

[0089] (Preparation of recovered resin composition pellets) Each of the recovered materials obtained above was dry-blended to a mass ratio of multilayer structure recovered material / single-layer film recovered material = 50 / 50. 100 parts by mass of the resulting dry-blended resin was further dry-blended with 1.25 parts by mass of EVA composition (B1) and 0.03 parts by mass of magnesium stearate (StMg) as a fatty acid divalent metal salt (D), and then melt-kneaded. Melt-kneading was performed using a twin-screw segment extruder "2D30W2" manufactured by Toyo Seiki Seisakusho Co., Ltd. (D(mm)=25, L / D=30, screw: fully meshed in the same direction) to a resin temperature of 220°C, obtaining recovered resin composition pellets (I) (cylindrical pellets with a diameter of 2 mm and a length of 4 mm). Furthermore, the obtained recovered resin composition pellets (II) were melt-kneaded again using the same melt-kneading operation as described above, and the melt-kneading operation was repeated a total of 5 times to obtain recovered resin composition pellets (II) (cylindrical pellets with a diameter of 2 mm and a length of 4 mm).

[0090] (Film formation of recovered single-layer film) 50 parts by mass of the recovered resin composition pellets (I) obtained above and 50 parts by mass of low-density polyethylene (LDPE; "Novatec (trademark) LJ400" manufactured by Nippon Polyethylene Co., Ltd.) were dry blended, and a single layer film was formed using a 20 mm extruder "D2020" manufactured by Toyo Seiki Seisakusho Co., Ltd. (D(mm)=20, L / D=20, compression ratio 3.5, screw: full flight) under the following conditions to obtain recovered single-layer film (I). Furthermore, a single layer film was formed under the same conditions as above, except that recovered resin composition pellets (II) were used instead of recovered resin composition pellets (I), to obtain recovered single-layer film (II). During the formation of the recovered single-layer film (II), the fish eye was evaluated according to the method described in evaluation method (4) above. The results are shown in Table 1. (Extrusion conditions) Extrusion temperature: Feed unit / Compression unit / Measuring unit / Die = 180 / 220 / 220 / 220℃ Screw rotation speed: 40 rpm Cooling roll temperature: 50℃ Film thickness: 25μm

[0091] The obtained recovered single-layer film (I) was evaluated for transparency according to the method described in evaluation method (3) above. The results are shown in Table 1.

[0092] Examples 2-38, Comparative Examples 1-11 Except for changing the content and type of PO(A), EVA composition(B), EVOH(C), fatty acid divalent metal salt(D), and adhesive resin(E) as shown in Table 1, multilayer structures, single-layer films, recovered resin composition pellets, and recovered single-layer films were prepared and evaluated in the same manner as in Example 1. The results are shown in Tables 1, 2, 3, and 4. In Comparative Examples 1 and 3, the production of EVA composition(B) pellets and the addition of EVA composition(B) during the production of recovered resin composition pellets were not performed. In Comparative Example 5, EVA(b1-1) was used as is as EVA composition(B8).

[0093] [Table 1]

[0094] [Table 2]

[0095] [Table 3]

[0096] [Table 4]

[0097] Example 39 (Preparation of recovery aid pellets) 97.5 parts by mass of the EVA composition (B12) obtained in Example 21 and 2.5 parts by mass of magnesium stearate (StMg) as a fatty acid divalent metal salt (D) were dry blended and melt-molded using a twin-screw extruder (Toyo Seiki Mfg. Co., Ltd. twin-screw segment extruder "2D30W2" (D(mm)=25, L / D=30, screw: fully meshed in the same direction)) to obtain recovery aid pellets.

[0098] (Fabrication of multilayer structures) Using a co-extrusion multilayer casting apparatus, a multilayer structure (5-layer co-extruded multilayer cast film) was fabricated, consisting of a PO layer formed by dry-blending 3 parts by mass of the above-mentioned recovery aid pellets with 100 parts by mass of low-density polyethylene (LDPE; "Novatec® LJ400" manufactured by Nippon Polyethylene Co., Ltd.), a barrier layer made of EVOH(C) ("Eval® F171B" manufactured by Kuraray Co., Ltd.), and an adhesive layer made of maleic anhydride-modified polyethylene ("Admer® NF518" manufactured by Mitsui Chemicals, Inc.), with layer thicknesses and layer configurations of LDPE layer / maleic anhydride-modified polyethylene layer / EVOH layer / maleic anhydride-modified polyethylene layer / LDPE layer = 40 μm / 5 μm / 10 μm / 5 μm / 40 μm. The film fabrication conditions at this time are shown below. Co-extrusion conditions PO layer extrusion temperature: Feed unit / Compression unit / Measuring unit / Die = 180 / 220 / 220 / 220℃ Barrier layer extrusion temperature: Feed unit / Compression unit / Measuring unit / Die = 180 / 220 / 220 / 220℃ Extrusion temperature of the adhesive layer: Feed unit / Compression unit / Measuring unit / Die = 180 / 220 / 220 / 220℃ Extruder: • PO layer 32φ extruder GT-32-A type (manufactured by Plastics Engineering Research Institute Co., Ltd.) • Barrier layer 20φ extruder, laboratory type ME CO-EXT (manufactured by Toyo Seiki Seisakusho Co., Ltd.) • Adhesive layer: 25φ extruder P25-18-AC type (manufactured by Osaka Seiki Kogyo Co., Ltd.) T-die: 300mm width, 3 types, 5 layers (manufactured by Plastics Engineering Laboratory Co., Ltd.) Cooling roll temperature: 80℃ Pickup speed: 3.0m / min

[0099] (Preparation of single-layer film) Except for changing the resin used in each extruder to low-density polyethylene (LDPE; "Novatec® LJ400" manufactured by Nippon Polyethylene Co., Ltd.), the film was fabricated in the same manner as the above-mentioned multilayer structure, and a 100 μm thick LDPE single-layer film was obtained.

[0100] (Crush) The multilayer structure obtained above was crushed using an 8mm diameter mesh pulverizer to produce a recovered multilayer structure. Similarly, the single-layer film obtained above was crushed using an 8mm diameter mesh pulverizer to produce a recovered single-layer film.

[0101] (Preparation of recovered resin composition pellets) Each of the recovered materials obtained above was dry-blended to a mass ratio of multilayer structure recovered material / single-layer film recovered material = 50 / 50, and then melt-kneaded. Melt-kneading was performed using a twin-screw segment extruder "2D30W2" manufactured by Toyo Seiki Seisakusho Co., Ltd. (D(mm)=25, L / D=30, screw: fully meshed in the same direction), and the resin temperature was maintained at 220°C to obtain recovered resin composition pellets (I) (cylindrical pellets with a diameter of 2 mm and a length of 4 mm).

[0102] (Preparation of multilayer film containing a recovered resin composition layer (recovered multilayer film)) Using a co-extrusion multilayer casting apparatus, a multilayer film was produced consisting of a PO layer formed by melt-extruding a group of pellets dry-blended from 50 parts by mass of low-density polyethylene (LDPE; "Novatec® LJ400" manufactured by Nippon Polyethylene Co., Ltd.) and 50 parts by mass of recovered resin composition pellets (I), a barrier layer made of EVOH(C) ("Eval® F171B" manufactured by Kuraray Co., Ltd.), and an adhesive layer made of maleic anhydride-modified polyethylene ("Admer® NF518" manufactured by Mitsui Chemicals, Inc.). The film had a layer thickness and layer structure of 40 μm / 5 μm / 10 μm / 5 μm / 40 μm. (Recovered multilayer film (5-layer co-extruded multilayer cast film)). As a control, a multilayer film was produced in which the PO layer consisted of low-density polyethylene (LDPE; "Novatec® LJ400" manufactured by Nippon Polyethylene Co., Ltd.), the barrier layer consisted of EVOH(C) ("Eval® F171B" manufactured by Kuraray Co., Ltd.), and the adhesive layer consisted of maleic anhydride-modified polyethylene ("Admer® NF518" manufactured by Mitsui Chemicals, Inc.). This multilayer film had a layer thickness and layer structure of 40 μm / 5 μm / 10 μm / 5 μm / 40 μm (a 5-layer co-extruded multilayer cast film). The extrusion processability of the pellet group containing the recovered resin composition pellet (I) was stable and good. Furthermore, the recovered multilayer film had almost no difference in the amount of fisheye and transparency compared to the multilayer film containing the LDPE layer, and had a good appearance.

[0103] Comparative Example 12 A multilayer structure, a single-layer film, recovered resin composition pellets, a recovered multilayer film, and a multilayer film containing a polyethylene layer were prepared in the same manner as in Example 39, except that the recovered additive pellets were not blended into the PO layer of the multilayer structure. The extrudeability of the recovered composition was stable and good, but the recovered multilayer film showed increased fisheye and decreased transparency compared to the multilayer film containing the LDPE layer.

[0104] Example 40 Except for changing the layer thickness and layer composition of the recovered multilayer film to a recovered multilayer film (7-layer co-extruded multilayer cast film) having a layer thickness and layer composition of LDPE layer / recovered resin composition layer / maleic anhydride modified polyethylene layer / EVOH layer / maleic anhydride modified polyethylene layer / recovered resin composition layer / LDPE layer = 20 μm / 20 μm / 5 μm / 10 μm / 5 μm / 20 μm / 20 μm, a multilayer film including a recovered aid pellet, a multilayer structure, a single-layer film, a recovered resin composition pellet, and a recovered multilayer film and polyethylene layer were prepared in the same manner as in Example 39. The extrusion processability of the pellet group including the recovered resin composition pellet (I) was stable and good. Furthermore, the recovered multilayer film had almost no difference in the amount of fisheye and transparency compared to the multilayer film including the LDPE layer, and had a good appearance.

[0105] Comparative Example 13 Except for not blending recovery aid pellets into the PO layer of the multilayer structure, a multilayer structure, a single-layer film, recovered resin composition pellets, a recovered multilayer film, and a multilayer film containing a polyethylene layer were prepared in the same manner as in Example 40. The extrudeability of the recovered composition was stable and good, but the recovered multilayer film showed increased fisheye and decreased transparency compared to the multilayer film containing the LDPE layer.

Claims

1. The present invention comprises a polyolefin (A), an ethylene-vinyl acetate copolymer composition (B) containing two or more ethylene-vinyl acetate copolymers with different ethylene unit contents, an ethylene-vinyl acetate copolymer saponified product (C) having an ethylene unit content of 20 to 55 mol% and a degree of saponification of 95 mol% or more, and a fatty acid divalent metal salt (D), wherein the ethylene unit content of the ethylene-vinyl acetate copolymer composition (B) is 60 to 87 mol%, the degree of saponification is 5 mol% or less, and the acid modification amount is 0.01 mmol / g or less. Polyolefin (A) is a resin composition that is a polyethylene-based resin.

2. The resin composition according to claim 1, wherein the ethylene-vinyl acetate copolymer composition (B) comprises two or more ethylene-vinyl acetate copolymers with different ethylene unit contents, and the difference in ethylene unit content of at least one pair of ethylene-vinyl acetate copolymers is 5 to 50 mol%.

3. The resin composition according to claim 1, wherein the mass ratio (B / C) of the ethylene-vinyl acetate copolymer composition (B) to the ethylene-vinyl acetate copolymer saponified product (C) is 0.05 to 2.

4. The resin composition according to claim 1, wherein the mass ratio (B / D) of the ethylene-vinyl acetate copolymer composition (B) to the fatty acid divalent metal salt (D) is 3 to 100.

5. The resin composition according to claim 1, wherein the mass ratio (C / D) of ethylene-vinyl acetate copolymer saponified (C) to fatty acid divalent metal salt (D) is 10 to 1000.

6. The resin composition according to claim 1, wherein the difference in refractive index (A-B) between the polyolefin (A) and the ethylene-vinyl acetate copolymer composition (B) is 0.015 to 0.050, and the difference in refractive index (C-B) between the ethylene-vinyl acetate copolymer saponified product (C) and the ethylene-vinyl acetate copolymer composition (B) is 0.001 to 0.

080.

7. The resin composition according to claim 1, wherein the content of polyolefin (A) is 80 to 99% by mass, the content of ethylene-vinyl acetate copolymer composition (B) is 0.10 to 6.0% by mass, the content of ethylene-vinyl acetate copolymer saponified product (C) is 0.10 to 20% by mass, and the content of fatty acid divalent metal salt (D) is 0.005 to 0.50% by mass.

8. A method for producing a resin composition according to any one of claims 1 to 7, comprising the step of melt-kneading a multilayer structure having a layer mainly composed of polyolefin (A) and a layer mainly composed of ethylene-vinyl acetate copolymer saponified (C), wherein at least one of the layers constituting the multilayer structure contains at least one selected from the group consisting of ethylene-vinyl acetate copolymer composition (B) and fatty acid divalent metal salt (D).

9. A multilayer structure used in the manufacturing method according to claim 8, comprising a layer mainly composed of polyolefin (A) and a layer mainly composed of ethylene-vinyl acetate copolymer saponified (C), wherein at least one of the layers constituting the multilayer structure comprises at least one selected from the group consisting of ethylene-vinyl acetate copolymer composition (B) and fatty acid divalent metal salt (D).

10. A method for producing the resin composition according to claim 1 or 2, comprising the step of mixing and melt-kneading a multilayer structure having a layer mainly composed of polyolefin (A) and a layer mainly composed of ethylene-vinyl acetate copolymer saponified (C) with a recovery aid, wherein the recovery aid comprises an ethylene-vinyl acetate copolymer composition (B) and a fatty acid divalent metal salt (D).

11. A recovery aid used in the production method according to claim 10, comprising an ethylene-vinyl acetate copolymer composition (B) and a fatty acid divalent metal salt (D).

Images