Resin composition, multilayer structure, film, packaging material, pouch, second molded article, and method for manufacturing resin composition

Abstract

Provided is a resin composition having excellent appearance and mechanical properties even when containing an ethylene-vinyl alcohol copolymer and a polyolefin resin. A resin composition containing an ethylene-vinyl alcohol copolymer (A), a polyethylene resin (B), and a polyolefin resin (C) having a polar group, the polyethylene resin (B) containing a structural unit derived from 1-hexene and / or 1-octene, and the polyethylene resin (B) having a weight average molecular weight of 230,000 or more, the polyolefin resin (C) having a polar group has a melt flow rate (190 DEG C, load of 2160 g) of 0.15-50 g / 10 min as measured in accordance with JIS K7210: 2014.

Description

Technical Field

[0001] This invention relates to resin compositions, multilayer structures, films, packaging materials, pouches, secondary molded articles, and methods for manufacturing resin compositions. Background Technology

[0002] Ethylene-vinyl alcohol copolymer (hereinafter sometimes referred to as "EVOH"), polyolefin resins, etc. are usually used to form multi-layered structures such as films and containers for food packaging by melt molding.

[0003] To reduce the amount of plastic packaging material waste and decrease the environmental burden, the following operations were carried out: used resin products that used these EVOH and polyolefin resins, resin debris, ends, or defective products generated during the manufacturing process of resin products were recycled, and the recycled products were recycled again in the form of a resin composition containing EVOH and polyolefin. However, the EVOH in the resin composition obtained by this operation is not compatible with the polyolefin resin, resulting in poor recyclability. Therefore, in order to improve the compatibility between EVOH and polyolefin resin, a compatibilizer was added.

[0004] For example, Patent Document 1 discloses a resin composition in which, as a compatibilizer, it contains an ethylene-vinyl acetate copolymer and EVOH with an ethylene content of 70 mol% or more, wherein the content of the aforementioned EVOH is 1 to 30 parts by mass relative to 100 parts by mass of the ethylene-vinyl acetate copolymer.

[0005] Furthermore, Patent Document 2 discloses a resin composition containing a polyolefin, EVOH with an ethylene content of 20-60 mol% and a saponification degree of 96% or more for vinyl acetate units, a specific amount of a higher fatty acid metal salt with 8-22 carbon atoms, a conjugated polyene compound with a boiling point of 20°C or more, an ethylene-vinyl acetate copolymer (EVAc), and an ethylene-vinyl acetate copolymer saponified product (S-EVOH) with an ethylene content of 68-98 mol% and a saponification degree of 20% or more for vinyl acetate units. The mass ratio of polyolefin to EVOH is 60:40 to 99.9:0.1, and it contains a higher fatty acid metal salt in the range of 0.0001 to 10 parts by mass relative to 100 parts by mass of the total amount of polyolefin and EVOH, contains a conjugated polyene compound in the range of 0.000001 to 1 part by mass relative to 100 parts by mass of the total amount of polyolefin and EVOH, and contains EVAc and S-EVOH in the range of 0.3 parts by mass or more relative to 100 parts by mass of the total amount of polyolefin and EVOH.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2009-97010

[0009] Patent Document 2: International Publication No. 2010 / 079851 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] While the technologies disclosed in the aforementioned patent documents 1 and 2 can improve the compatibility of EVOH with polyolefin resins, they are not sufficient. Further improvements are sought in appearance (transparency) and mechanical properties, especially impact resistance. Furthermore, when using multilayer structures containing EVOH and polyolefins as recycled raw materials, the appearance and mechanical properties tend to deteriorate. Therefore, further improvements are sought in appearance and mechanical properties when using recycled raw materials.

[0012] Therefore, the present invention provides resin compositions that have excellent appearance and mechanical properties even when containing EVOH and polyolefin resins, and in particular resin compositions that have excellent transparency and mechanical properties even when EVOH and polyolefins are used as recycled raw materials.

[0013] In view of this situation, the inventors have repeatedly conducted in-depth research and found that the aforementioned problems can be solved by using EVOH, polyethylene resin with specific structural units and weight-average molecular weight, and polyolefin resin with specific melt flow rate and containing polar groups.

[0014] That is, the present invention has the following aspects.

[0015] [1] A resin composition comprising EVOH (A), polyethylene resin (B), and a polyolefin resin having polar groups (C),

[0016] The aforementioned polyethylene resin (B) contains structural units derived from 1-hexene and / or 1-octene.

[0017] The aforementioned polyethylene resin (B) has a weight-average molecular weight of over 230,000.

[0018] The melt flow rate (190°C, 2160g load) of the aforementioned polyolefin resin (C) with polar groups, as measured according to JIS K7210:2014, is 0.15 to 50 g / 10 minutes.

[0019] [2] According to the resin composition of [1], the content ratio of EVOH (A) to the aforementioned polyethylene resin (B) [(A) / (B)] is 40 / 60 to 0.1 / 99.9 by mass.

[0020] [3] According to the resin composition of [1] or [2], wherein the content of structural units derived from 1-hexene and / or 1-octene in the aforementioned polyethylene resin (B) is 2.0 mol% or more.

[0021] [4] The resin composition according to any one of [1] to [3], wherein the density of the aforementioned polyethylene resin (B) is 0.850 to 0.920 g / cm³. 3 .

[0022] [5] A multilayer structure having at least one layer comprising a resin composition as described in any one of [1] to [4].

[0023] [6] A film comprising any one of the resin compositions described in [1] to [4].

[0024] [7] A packaging material comprising any one of the resin compositions described in [1] to [4].

[0025] [8] A pouch comprising any one of the resin compositions described in [1] to [4].

[0026] [9] A secondary molded article comprising any one of the resin compositions described in [1] to [4].

[0027]

[10] A method for manufacturing a resin composition, which is a method for manufacturing the resin composition described in any one of [1] to [4],

[0028] The method includes a step of mixing the aforementioned EVOH (A), polyethylene resin (B), and polyolefin resin (C) with polar groups.

[0029] The effects of the invention

[0030] The resin composition of the present invention exhibits excellent transparency and impact resistance, especially when EVOH and polyolefins are used as recycled raw materials, its transparency and mechanical properties are also excellent. Detailed Implementation

[0031] The present invention will now be described in more detail with reference to embodiments thereof, but the present invention is not limited to these embodiments.

[0032] In this specification, when “x~y” (x and y are any numbers) are used, unless otherwise specified, they include the meaning of “x and below”, as well as the meaning of “preferably greater than x” or “preferably less than y”.

[0033] In addition, when written as "x or above" (where x is any number), unless otherwise specified, it includes the meaning of "preferably greater than x". When written as "y or below" (where y is any number), unless otherwise specified, it includes the meaning of "preferably less than y".

[0034] Furthermore, "x and / or y (x and y can be any combination)" refers to at least one of x and y, and can mean only x, only y, or both x and y.

[0035] Regarding the numerical ranges described in this specification, the upper or lower limit of a numerical range for a certain stage can be arbitrarily combined with the upper or lower limits of numerical ranges for other stages. Furthermore, within the numerical ranges described in this specification, the upper or lower limit of that range can also be replaced with the values ​​shown in the embodiments.

[0036] Hereinafter, the monomer units contained in the copolymer resin will sometimes be referred to simply as "units". For example, ethylene-based monomer units are sometimes called "ethylene units".

[0037] The resin composition (hereinafter referred to as "this resin composition") according to one embodiment of the present invention comprises EVOH (A), a polyethylene resin (B) having a specific structural unit, and a polyolefin resin (C) having polar groups.

[0038] Furthermore, the aforementioned EVOH (A), polyethylene resin (B), and polyolefin resin (C) with polar groups can be either new or recycled. Recycled products are preferred, and from the viewpoint of the effectiveness of this invention, it is particularly preferable to use waste materials such as multilayer structures containing EVOH (A) and polyethylene resin (B), and end materials of multilayer structures, as raw materials.

[0039] The following is an explanation of each ingredient.

[0040] [EVOH(A)]

[0041] The aforementioned EVOH(A) is typically a resin obtained by saponifying a copolymer of ethylene and vinyl ester monomers, i.e., an ethylene-vinyl ester copolymer, which is a non-water-soluble thermoplastic resin. For economic reasons, vinyl acetate is usually used as the vinyl ester monomer. The polymerization method for ethylene and vinyl ester monomers can be 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. EVOH(A) produced in this manner is primarily composed of ethylene-derived structural units and vinyl alcohol structural units, and typically contains a certain amount of unsaponified vinyl ester structural units remaining.

[0042] Vinyl acetate is the most commonly used vinyl ester monomer from the viewpoints of market availability and efficient impurity removal during manufacturing. Other vinyl ester monomers include aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl neovalerate, vinyl decanoate, vinyl laurate, vinyl stearate, and vinyl tert-carbonate, as well as aromatic vinyl esters such as vinyl benzoate. Generally, aliphatic vinyl esters with 3 to 20 carbon atoms, preferably 4 to 10, and particularly preferably 4 to 7 carbon atoms, are used. These can be used alone or in combination of two or more.

[0043] The aforementioned vinyl ester monomers typically use petroleum-derived raw materials such as naphtha, or natural gas-derived raw materials such as shale gas, or plant-derived raw materials refined from sugars, sugar beets, corn, potatoes, etc., containing sugars and starches, or cellulose-derived raw materials such as rice, wheat, millet, etc.

[0044] The ethylene unit content in EVOH(A) can be controlled by the ethylene pressure during copolymerization of the vinyl ester monomer and ethylene, and is preferably 20-60 mol%. More preferably, it is 25-55 mol%, further preferably 28-50 mol%, particularly preferably 30-45 mol%, and especially preferably 32-45 mol%. Furthermore, from the viewpoint of further improving mechanical properties and secondary molding properties, EVOH(A) preferably contains EVOH with an ethylene unit content of 32 mol% or more. If this content is too low, there is a tendency for reduced gas barrier properties and melt moldability under high humidity; conversely, if it is too high, there is a tendency for reduced gas barrier properties. It should be noted that the ethylene unit content can be determined according to, for example, ISO 14663.

[0045] Furthermore, the degree of saponification of the vinyl ester component in EVOH(A) can be controlled based on the amount, temperature, and time of the saponification catalyst (usually an alkaline catalyst such as sodium hydroxide) used during the saponification of the ethylene-vinyl ester copolymer. From the viewpoints of barrier properties, thermal stability, and moisture resistance, it is preferably 80 mol% or more, more preferably 90 mol% or more, more preferably 98 mol% or more, particularly preferably 99 mol% or more, and can be 100 mol%.

[0046] The degree of saponification of the vinyl ester unit of the aforementioned EVOH(A) was measured according to JIS K6726 (wherein, EVOH is prepared as a solution uniformly dissolved in water / methanol solvent).

[0047] The melt flow rate (MFR) of EVOH(A) (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 it is too low, the viscosity tends to become too high, making melt extrusion difficult.

[0048] MFR serves as an indicator of the degree of polymerization of EVOH(A), and can be adjusted based on the amount of polymerization initiator and solvent used when copolymerizing ethylene with vinyl ester monomers.

[0049] EVOH(A) can copolymerize polymerizable monomers other than ethylene and vinyl ester monomers within a range typically less than 5 mol% without impairing the effects of the present invention. Examples of such polymerizable monomers include, for instance, α-olefins such as propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; hydroxyl-containing α-olefins such as 3-buten-1-ol, 4-penten-1-ol, and 3-buten-1,2-diol, and their esterifications, acylates, and other hydroxyl-containing α-olefin derivatives; hydroxymethyl vinylidene diacetate esters such as 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyryloxy-2-methylenepropane; unsaturated carboxylic acids or their salts, partially alkyl esters, fully alkyl esters, nitriles, amides, or anhydrides; unsaturated sulfonic acids or their salts; vinylsilane compounds; vinyl chloride; styrene, etc. These monomers can be used alone or in combination of two or more.

[0050] Furthermore, as the EVOH(A) used in this invention, EVOH having primary hydroxyl groups in the side chain can be optionally used. Examples of EVOH having primary hydroxyl groups in the side chain include EVOH obtained by copolymerizing α-olefins containing hydroxyl groups and EVOH having a 1,2-diol structure in the side chain.

[0051] When using EVOH with a primary hydroxyl group on the side chain, the content of the structural unit derived from the monomer having the primary hydroxyl group is generally preferably 0.1 to 20 mol% of the EVOH, more preferably 0.5 to 15 mol%, and particularly preferably 1 to 10 mol%.

[0052] It should be noted that, in this invention, EVOH with side chains that do not have primary hydroxyl groups is preferred.

[0053] Furthermore, EVOH that has undergone "post-modification" such as urethane esterification, acetalization, cyanoethylation, and oxyalkyleneification can also be used as EVOH(A).

[0054] EVOH(A) can be used with only one type, or two or more types of substances with different types of vinyl esters, ethylene unit content, physical properties, etc. can be mixed together.

[0055] It should be noted that, from the point of view of compatibility, EVOH is preferably composed of only one type, or, in the case of using multiple types, it is preferable to be composed of types with melting points of 170°C or higher, or types with melting points of less than 170°C.

[0056] In this invention, the melting point is determined as follows: following the method described in JIS K7121, the sample is temporarily heated to 200°C using a differential scanning calorimeter (DSC), then cooled to a temperature approximately 50°C lower than the glass transition temperature at a cooling rate of 30°C / min, and then heated again at a heating rate of 10°C / min for measurement (second run).

[0057] The content of EVOH(A) in the aforementioned resin composition is typically 0.1 to 40% by mass, preferably 0.3 to 35% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.7 to 25% by mass. If the content of EVOH(A) is within the aforementioned range, there is a tendency for the resulting molded article to have a good appearance and excellent mechanical properties.

[0058] [Polyethylene resin (B)]

[0059] The polyethylene resin (B) used in this invention contains structural units derived from ethylene and structural units derived from 1-hexene and / or 1-octene. By including structural units derived from 1-hexene and / or 1-octene in the polyethylene resin (B), mechanical properties can be improved.

[0060] The content of structural units derived from 1-hexene and / or 1-octene in the aforementioned polyethylene resin (B) is preferably 2.0 mol% or more, more preferably 3.0 mol% or more, further preferably 3.2 mol% or more, particularly preferably 3.4 mol% or more, and most preferably 3.6 mol% or more. There is no particular upper limit, but it is typically 15 mol%, preferably 13 mol%, more preferably 11 mol%, and particularly preferably 10 mol%. By ensuring the content of structural units derived from 1-hexene and / or 1-octene is within the aforementioned range, there is a tendency for the resin to exhibit good flexibility and excellent mechanical properties.

[0061] The density of the aforementioned polyethylene resin (B) is 0.850–0.920 g / cm³. 3 The preferred value is 0.860–0.920 g / cm³. 3 More preferably, it is 0.870–0.920 g / cm³. 3 More preferably, it is 0.880–0.920 g / cm³. 3By keeping the density within the aforementioned range, there is a tendency to easily obtain the effects of the present invention. The density can be measured using a hydrometer.

[0062] The specific polyethylene resin (B) is not particularly limited, and examples include linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, and high-density polyethylene. Additionally, examples of polyethylene resin (B) include modified polyethylene resins such as unsaturated carboxylic acid-modified polyethylene resins obtained by grafting unsaturated carboxylic acids or their esters onto polyethylene resin. These can be used alone or in combination of two or more.

[0063] The preferred form is linear low-density polyethylene. Furthermore, the raw materials for the aforementioned polyethylene resin can be derived from petroleum or from plants.

[0064] The aforementioned polyethylene resin (B) is obtained by polymerizing a copolymer containing ethylene and 1-hexene and / or 1-octene. As a copolymer, other α-olefins besides 1-hexene and 1-octene may be included.

[0065] Other α-olefins mentioned above include those with 2 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-heptene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetracene, 1-tetradecene, 1-pentadecaene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecaene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene, and 2,2,4-trimethyl-1-pentene. These can be used alone or in combination of two or more.

[0066] When the aforementioned polyethylene resin (B) contains structural units derived from other α-olefins, its content is typically 5 mol% or less, preferably 2 mol% or less.

[0067] The aforementioned polyethylene resin (B) has a weight-average molecular weight (WM) of 230,000 or more (converted to polystyrene), more preferably 235,000 or more, further preferably 240,000 or more, particularly preferably 245,000 or more, especially preferably 250,000 or more, and most preferably 253,000 or more. It should be noted that the upper limit is not particularly limited, and is typically 400,000. By ensuring that the WM of polyethylene resin (B) is 230,000 or more (converted to polystyrene), there is a tendency for it to have excellent mechanical properties. The WM of polyethylene resin (B) can be determined using GPC.

[0068] The melt flow rate (MFR, 190°C, 2160g load) of polyethylene resin (B), as measured according to JIS K 7210:2014, is not particularly limited, but from a moldability point of view, it is generally 0.01 to 50 g / 10 min, more preferably 0.1 to 10 g / 10 min. The MFR can be measured using a melt index meter.

[0069] Commercially available products of the preferred polyethylene resin (B) of the present invention include, for example, Innate (registered trademark) manufactured by Dow Chemical Co., Ltd., Exceed (registered trademark) manufactured by Exxon Mobil Co., Ltd., and NOVATEC (registered trademark) manufactured by Nippon Polyethylene Co., Ltd.

[0070] The content of the aforementioned polyethylene resin (B) in the resin composition is typically 60 to 99.8% by mass, preferably 65 to 99.7% by mass, more preferably 70 to 99.5% by mass, and particularly preferably 75 to 99.3% by mass. If the content of polyethylene resin (B) is within the aforementioned range, there is a tendency for the resulting molded article to have a good appearance and excellent mechanical properties.

[0071] Furthermore, the content ratio of EVOH(A) to the aforementioned polyethylene resin (B) [(A) / (B)] is preferably 40 / 60 to 0.1 / 99.9 by mass, more preferably 35 / 65 to 0.3 / 99.7, even more preferably 30 / 70 to 0.5 / 99.5, and particularly preferably 25 / 75 to 0.7 / 99.3. If the content ratio of polyethylene resin (B) to EVOH(A) is within the aforementioned range, there is a tendency for the resulting molded article to have a good appearance and excellent mechanical properties.

[0072] In this resin composition, it is preferable to form an island structure by dispersing EVOH(A) in the form of an island phase within the marine phase (matrix) of polyethylene resin (B). If polyethylene resin (B) and EVOH(A) form an island structure, there is a tendency for the resulting molded article to have a good appearance and excellent mechanical properties.

[0073] [Polyolefin resins with polar groups (C)]

[0074] Examples of polyolefin resins containing polar groups include, for instance, polyolefin resins containing carboxyl groups obtained by chemically bonding unsaturated carboxylic acids or their anhydrides to the polyolefin resin through addition reactions, grafting reactions, etc.

[0075] Examples of carboxyl-containing polyolefin resins include, for instance, 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. These can be used alone or in mixtures of two or more.

[0076] As a polyolefin resin (C) with polar groups, it is particularly suitable for maleic anhydride-modified polyolefin resins such as maleic anhydride-modified polyethylene and maleic anhydride-modified ethylene-α-olefin copolymer, from the viewpoint that it also helps to suppress gelation during melting and heating and to suppress the reduction of transparency.

[0077] The melt flow rate (MFR, 190°C, 2160g load) of the polyolefin resin (C) with polar groups, as measured according to JIS K7210:2014, is 0.15 to 50 g / 10 min, preferably 0.4 to 40 g / 10 min, more preferably 0.7 to 30 g / 10 min, even more preferably 1 to 25 g / 10 min, and particularly preferably 1.2 to 20 g / 10 min. If the MFR of the polyolefin resin (C) with polar groups is within the aforementioned range, the processability is excellent, the resulting molded article has a good appearance, and the mechanical properties are excellent. Conversely, if the melt flow rate of the polyolefin resin (C) with polar groups is outside the aforementioned range, the processability, appearance, and mechanical properties decrease.

[0078] It should be noted that if the aforementioned melt flow rate is expressed in terms of melt viscosity calculated according to the following formula (1), then 0.15 g / 10 min is about 1,650,000 cP and 50 g / 10 min is about 205,000 cP.

[0079] MFR (190℃, load 2160g) = 3.6126

[10] (log(η)-6.6928) / -1.1363 -9.31851…(1)

[0080] Here, in equation (1), η is the melt viscosity at 350°F.

[0081] The acid value of polyolefin resins (C) with polar groups 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, there is a tendency for the number of reaction sites to react with the hydroxyl groups in EVOH to increase, leading to the formation of highly polymerized compounds during melt mixing, reduced stability during extrusion processing, and difficulty in obtaining good 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 aforementioned acid value is determined according to JIS K0070.

[0082] The content of the aforementioned polyolefin resin (C) with polar groups in the resin composition is typically 0.1 to 40% by mass, preferably 0.3 to 35% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.7 to 25% by mass. If the content of the polyolefin resin (C) with polar groups is within the aforementioned range, there is a tendency for the resulting molded article to have a good appearance and excellent mechanical properties.

[0083] This resin composition may contain components other than those described above, provided that the effects of the present invention are not impaired. These may include anti-blocking agents, processing aids, resins other than EVOH (A), polyethylene resin (B), and polyolefin resins with polar groups (C), carboxylic acid compounds, phosphate compounds, boron compounds, metal salts, stabilizers, antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, surfactants, desiccants, crosslinking agents, and reinforcing agents for various fibers, etc. These components may be used alone or in combination of two or more.

[0084] [Method for manufacturing the resin composition]

[0085] This resin composition can be manufactured by a manufacturing method including the process of mixing the aforementioned EVOH (A), polyethylene resin (B), and polyolefin resin (C) having polar groups, such as dry mixing or melt mixing. These manufacturing methods can also be combined arbitrarily.

[0086] Furthermore, as described above, the aforementioned EVOH (A), polyethylene resin (B), and polyolefin resin with polar groups (C) can be either virgin or recycled. From the viewpoint of the effectiveness of this invention, it is particularly preferable to use waste materials such as multilayer structures containing EVOH (A) and polyethylene resin (B), and end materials of multilayer structures, as raw materials.

[0087] Generally, laminates containing layers of EVOH and layers of polyethylene resin are widely used as packaging materials. When this laminate containing EVOH and polyethylene resin is directly recycled and used as a raw material for resin compositions, there is a tendency for poor compatibility between EVOH and polyethylene resin, resulting in reduced appearance and mechanical properties. However, it has been found that in this invention, by using a specific polyethylene resin (B) and a polyolefin resin (C) with polar groups, both good appearance and excellent mechanical properties are achieved.

[0088] When using the aforementioned recycled material, its content is 50% by mass or less, preferably 40% by mass or less, and particularly preferably 30% by mass or less of the resin composition. Excessive recycled material content tends to result in poor transparency and impact resistance.

[0089] Examples of the aforementioned dry mixing methods include (i) using a drum or similar device to dry mix granular EVOH resin (A), polyethylene resin (B), and polyolefin resin (C) with polar groups.

[0090] Examples of the aforementioned melt mixing method include (ii) a method for melt mixing a dry mixture made by dry mixing granular EVOH (A), polyethylene resin (B), and polyolefin resin (C) with polar groups; and (iii) a method for melt mixing molten EVOH (A), polyethylene resin (B), and polyolefin resin (C) with polar groups.

[0091] As described above, the different methods mentioned above can be combined in this invention. From the viewpoint of productivity and obtaining a resin composition with more significant effects than those of this invention, melt mixing is preferred, and method (ii) is particularly preferred. Furthermore, when using other thermoplastic resins or other compounding agents mentioned above, compounding can be performed according to known manufacturing methods and using conventional methods.

[0092] The shape of the resin composition obtained by the aforementioned manufacturing methods is arbitrary, but granules are preferred.

[0093] The aforementioned granules can be spherical, elliptical, cylindrical, cubic, or cuboid in shape, but are typically elliptical or cylindrical. Regarding their size, from the viewpoint of convenience when used as molding materials, in the case of an elliptical shape, the minor axis is typically 1–10 mm, preferably 2–6 mm, and more preferably 2.5–5.5 mm, and the major axis is typically 1.5–30 mm, preferably 3–20 mm, and more preferably 3.5–10 mm. In the case of a cylindrical shape, the diameter of the base is typically 1–6 mm, preferably 2–5 mm, and the length is typically 1–6 mm, preferably 2–5 mm.

[0094] In addition, the granular EVOH (A), polyethylene resin (B), and polyolefin resin with polar groups (C) used in the aforementioned manufacturing methods are preferably the same in shape and size.

[0095] Furthermore, when the resin composition is in the form of granules, from the viewpoint of stabilizing the feedability during melt molding, it is preferable to adhere a known lubricant to the surface of the granules. Examples of lubricants include, for instance, higher fatty acids with 12 or more carbon atoms (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid esters (methyl esters, isopropyl esters, butyl esters, octyl esters, etc. of higher fatty acids), higher fatty acid amides (e.g., saturated higher fatty acid amides such as laurylamide, myristicamide, palmitamide, stearamide, behenicamide, etc.; unsaturated higher fatty acid amides such as oleamide, erucamide, etc.; bis-higher fatty acid amides such as ethylene bis-stearamide, ethylene bis-oleamide, ethylene bis-erucamide, ethylene bis-lauramide, etc.), low molecular weight polyolefins (e.g., low molecular weight polyethylene or low molecular weight polypropylene with a molecular weight of approximately 500 to 10,000, or their acid-modified forms), higher alcohols with 6 or more carbon atoms, ester oligomers, fluoroethylene resins, etc. These compounds can be used alone or in combination of two or more. Furthermore, the content of this lubricant is typically 5% by mass or less, preferably 1% by mass or less, of the resin composition. It should be noted that the lower limit is typically 0% by mass.

[0096] The resin composition obtained by this operation has excellent transparency and impact resistance.

[0097] The total haze of this resin composition is preferably 60% or less, more preferably 55% or less, and particularly preferably 50% or less.

[0098] The aforementioned total haze was determined by forming the resin composition into a single-layer film with a thickness of 30 μm and measuring it using a haze meter.

[0099] The impact strength (g) of this resin composition is preferably 50g or more, more preferably 200g or more, further preferably 400g or more, and particularly preferably 600g or more.

[0100] The aforementioned impact strength (g) refers to the maximum mass of a 30μm thick monolayer film made from this resin composition, when a 38mm thick monolayer film is dropped from a height of 0.66m onto a 32g dart made of phenolic plastic using a dart impact tester, without damaging the monolayer film.

[0101] This resin composition is prepared in various forms such as granules, powders, or liquids, and is provided as a molding material for various molded articles.

[0102] Examples of the aforementioned molded articles include, for instance, packaging materials, pouches, and multilayer structures having at least one layer formed from the resin composition, primarily single-layer films molded from this resin composition. Furthermore, the aforementioned molded articles can also undergo secondary processing as described later to produce secondary processed products.

[0103] [Multi-layer structure]

[0104] The multilayer structure (hereinafter referred to as "this multilayer structure") according to one embodiment of the present invention has at least one layer formed of the resin composition. The layer formed of the resin composition (hereinafter referred to as "this resin composition layer") can be further strengthened, protected from the influence of moisture, or given other functions by being laminated with a layer formed of a resin composition with a thermoplastic resin other than this resin composition as the main component (hereinafter referred to as "other resin layer").

[0105] Examples of the aforementioned thermoplastic resins include, for instance, linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, polypropylene, propylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, polybutene, polypentene, polycyclic olefin resins (polymers in which at least one of the main chain and side chain has a cyclic olefin structure), and other (unmodified) polyolefin resins. Hydrocarbons are grafted with unsaturated carboxylic acids or their esters to obtain unsaturated carboxylic acid-modified polyolefin resins, including modified olefin resins in a broad sense, as well as 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 chlorinated polyethylene and chlorinated polypropylene, and aromatic or aliphatic polyketides. These can be used alone or in combination of two or more.

[0106] Among these, polyamide resin, polyolefin resin, polyester resin, and polystyrene resin are preferred as hydrophobic resins, and polyolefin resins such as polyethylene resin, polypropylene resin, polycyclic olefin resin, and their unsaturated carboxylic acid modified polyolefin resins are more preferred.

[0107] When the resin composition layer is designated as a (a1, a2, ...) and other resin layers are designated as b (b1, b2, ...), the layer configuration of this 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, when the recycled layer containing the resin composition and a mixture of thermoplastic resins other than the resin composition, obtained by remelting and molding the ends, defective products, etc., generated during the manufacturing process of this multilayer structure, is designated as R, it can also be designated as b / R / a, b / R / a / b, b / R / a / R / b, b / a / R / a / b, b / R / a / R / a / R / b, etc. The total number of layers in this multilayer structure is typically 2 to 15, preferably 3 to 10. In the aforementioned layer configuration, an adhesive resin layer containing adhesive resin may be sandwiched between the layers as needed.

[0108] As the aforementioned adhesive resin, any known resin can be used, provided that it is appropriately selected based on the type of thermoplastic resin used in the other resin layer "b". For example, carboxyl-containing modified polyolefin polymers obtained by chemically bonding a polyolefin resin to an unsaturated carboxylic acid or its anhydride through addition reactions, grafting reactions, etc., can be listed. Examples of such carboxyl-containing modified polyolefin polymers include, for instance, 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. These can be used alone or in combination of two or more.

[0109] In this multilayer structure, when an adhesive resin layer is used between the resin composition layer and other resin layers, 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.

[0110] Among the aforementioned other resins and adhesive resins, within a range that does not hinder the spirit of the present invention (e.g., 30% or less by mass relative to the total resin, preferably 10% or less by mass), they may contain plasticizers, fillers, clays (montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants, nucleating agents, antiblocking agents, waxes, etc., as are known in the art. They may be used alone or in combination of two or more.

[0111] The lamination of the aforementioned resin composition layer with the aforementioned other resin layers (including the case where an adhesive resin layer is sandwiched) can be performed using known methods. Examples include methods such as melt extrusion lamination of the resin composition into films, sheets, etc., with other resins; methods of melt extrusion lamination of other resin layers with the resin composition; methods of co-extruding the resin composition with other resins; methods of dry lamination of the resin composition (layer) with other resin compositions or other resin layers using known adhesives such as organotitanium compounds, isocyanate compounds, polyester compounds, and polyurethane compounds; and methods of coating other resins with a solution of the resin composition and then removing the solvent. Among these, from the viewpoint of cost and environment, a manufacturing method that includes a step of melt molding the resin composition layer is preferred, and a co-extrusion method is particularly preferred.

[0112] This multi-layer structure can be subjected to (heated) stretching treatment as needed. The stretching treatment can be either uniaxial or biaxial stretching; 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, tube stretching, stretch blow molding, and vacuum forming, can be used. The stretching temperature is near the melting point of the multi-layer structure, typically selected from 40 to 170°C, preferably from approximately 60 to 160°C. If the stretching temperature is too low, the stretchability becomes poor; if it is too high, it is difficult to maintain a stable stretching state.

[0113] Furthermore, for the purpose of imparting dimensional stability, the stretched multilayer structure can be heat-fixed. Heat fixing can be carried out using known methods, for example, by holding the stretched multilayer structure under tension while performing a heat treatment typically at 80–180°C, preferably 100–165°C, for approximately 2–600 seconds.

[0114] When this multilayer structure, which has undergone the aforementioned stretching treatment, is used as a shrink film, in order to impart thermal shrinkability, the aforementioned heat fixation is not performed. Instead, treatments such as blowing cold air onto the stretched multilayer structure to cool and fix it are performed.

[0115] The thickness of this multilayer structure (including stretched multilayer structures), and consequently the thickness of the resin composition layers, other resin layers, and adhesive resin layers constituting the multilayer structure, varies depending on the layer composition, the type of other resins, the type of adhesive resin, the application, packaging form, and required physical properties. However, the thickness of this multilayer structure (including stretched multilayer structures) is typically 10–5000 μm, preferably 30–3000 μm, and particularly preferably 50–2000 μm. The thickness of the resin composition layers is typically 1–500 μm, preferably 3–300 μm, and particularly preferably 5–200 μm; the thickness of other resin layers is typically 5–3000 μm, preferably 10–2000 μm, and particularly preferably 20–1000 μm; and the thickness of the adhesive resin layers is typically 0.5–250 μm, preferably 1–150 μm, and particularly preferably 3–100 μm.

[0116] Furthermore, regarding the thickness ratio (resin composition layer / other resin layer) of the multilayer structure relative to other resin layers, when multiple layers exist, the ratio of the thickest layer to the others 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 multilayer structure relative to the adhesive resin layer, when multiple layers exist, the ratio of the thickest layer to the others is typically 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and particularly preferably 50 / 50 to 90 / 10.

[0117] Alternatively, this multi-layer structure can be used to obtain multi-layer containers such as cups, trays, packaging materials, and small bags. In this case, deep drawing is typically used, specifically vacuum forming, pneumatic forming, vacuum pneumatic forming, and pressure-assisted plug-type vacuum pneumatic forming. Furthermore, when obtaining multi-layer containers (laminated structures) in the shape of tubes or bottles from multi-layer preforms (hollow tubular preforms before blow molding), blow molding is used. Specifically, extrusion blow molding (double-head type, mold moving type, preform transfer type, rotary type, accumulator type, horizontal preform type, etc.), cooled preform blow molding, injection blow molding, and biaxial stretch blow molding (extrusion-type cooled preform biaxial stretch blow molding, injection-type cooled preform biaxial stretch blow molding, injection molding inline biaxial stretch blow molding, etc.) are examples.

[0118] Furthermore, the resulting multi-layer containers can also undergo secondary processing as needed, such as 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 slitting processing, to produce secondary processed products.

[0119] Regarding single-layer films formed from this resin composition, bags formed from this multi-layer structure, and containers and lids made of cups, trays, tubes, bottles, packaging materials, pouches, etc., in addition to general food, they are also useful as various packaging materials and containers for condiments such as mayonnaise and sauces, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, pharmaceuticals, etc.

[0120] Example

[0121] The present invention will now be described in detail through examples. However, the present invention is not limited to the following examples.

[0122] Before implementing the embodiments, prepare the following materials.

[0123] <EVOH(A)>

[0124] • A1: SOARNOL (registered trademark) DC3203RB manufactured by Mitsubishi Chemical Corporation (ethylene unit content 32 mol%, MFR 3.8 g / 10 min (210℃, load 2160 g), density 1.19 g / cm³). 3 )

[0125] <Polyethylene Resin (B)>

[0126] • B1: Exxon Mobil's "Exceed (registered trademark) 1012MA" (a copolymer of ethylene and 1-hexene, with 3.9 mol% of structural units derived from 1-hexene and a density of 0.912 g / cm³). 3 MFR (190℃, load 2160g) is 1.0g / 10min, weight-average molecular weight (converted from polystyrene) is 258000.

[0127] • B2: Exxon Mobil's "Exceed (registered trademark) XP 8784" (a copolymer of ethylene and 1-hexene, with 4.6 mol% of 1-hexene-derived structural units and a density of 0.914 g / cm³). 3 MFR (190℃, 2160g load) is 0.80g / 10min, weight-average molecular weight (converted from polystyrene) is 269000.

[0128] • B3: Dow Chemical's "Innate (registered trademark) ST50" (a copolymer of ethylene and 1-octene, containing 3.2 mol% of 1-octene-derived structural units, with a density of 0.918 g / cm³). 3 MFR (190℃, 2160g load) is 0.85g / 10min, weight-average molecular weight (converted from polystyrene) is 251000.

[0129] • B4: Dow Chemical's "Innate (registered trademark) TH60" (a copolymer of ethylene and 1-octene, containing 4.0 mol% of 1-octene-derived structural units, with a density of 0.912 g / cm³). 3 MFR (190℃, 2160g load) is 0.85g / 10min, weight-average molecular weight (converted from polystyrene) is 253000.

[0130] • B5: "Anteo (registered trademark) FK2715" manufactured by Borouge (a copolymer of ethylene and 1-hexene, with 1.6 mol% of structural units derived from 1-hexene and a density of 0.927 g / cm³). 3 MFR (190℃, load 2160g) is 1.3g / 10min, weight-average molecular weight (converted from polystyrene) is 240000.

[0131] •B'1: NOVATEC UF641 (a copolymer of ethylene and 1-butene, with a density of 0.927 g / cm³) manufactured by Nippon Polyethylene Co., Ltd. 3 MFR (190℃, load 2160g) is 2.1g / 10min, weight-average molecular weight (converted from polystyrene) is 220000.

[0132] •B'2: NOVATEC UF421 (a copolymer of ethylene and 1-butene, with a density of 0.926 g / cm³) manufactured by Nippon Polyethylene Co., Ltd. 3 MFR (190℃, load 2160g) is 0.9g / 10min, weight-average molecular weight (converted from polystyrene) is 262000.

[0133] • B'3: Dow Chemical's "ELITE (registered trademark) 5400G" (a copolymer of ethylene and 1-octene, containing 3.6 mol% of 1-octene-derived structural units, with a density of 0.916 g / cm³). 3 MFR (190℃, load 2160g) is 1.0g / 10min, weight-average molecular weight (converted from polystyrene) is 228000.

[0134] It should be noted that the weight-average molecular weight and the content of each copolymer component of the above-mentioned polyethylene resin (B) were measured by the evaluation method described later.

[0135] <Polyolefin resins with polar groups (C)>

[0136] • C1: "MODIC (registered trademark) M533" manufactured by Mitsubishi Chemical Corporation (density 0.92 g / cm³)3 MFR (190℃, load 2160g) is 2.5g / 10 minutes.

[0137] <Example 1>

[0138] Using a Φ40mm single-screw extruder, a substance obtained by dry mixing 5 parts by mass of EVOH (A1), 90 parts by mass of polyethylene resin (B1), and 5 parts by mass of polyolefin resin containing polar groups (C1) is melt-blended to obtain a resin composition.

[0139] The obtained resin composition was used to form a 30 μm single-layer film using a single-layer casting machine. The film forming conditions are shown below.

[0140] (Film-forming conditions)

[0141] Φ40mm single-screw extruder (barrel temperature 220℃)

[0142] Mold temperature: 220℃

[0143] Traction speed: 2.0~2.5m / min

[0144] <Examples 2-5, Comparative Examples 1-3>

[0145] The type of polyethylene resin (B) was changed as shown in Table 1 below. Otherwise, the same procedure was followed as in Example 1 to obtain the resin compositions of Examples 2-5 and Comparative Examples 1-3. In addition, the same procedure was followed as in Example 1 to prepare a single-layer film with a thickness of 30 μm from the obtained resin compositions of Examples 2-5 and Comparative Examples 1-3.

[0146] [Determination of weight-average molecular weight of polyethylene resin (B)]

[0147] Each polyethylene resin was weighed separately and dissolved in 1,2,4-trichlorobenzene solvent at 140°C for 1 hour. The dissolved samples were then used for high-temperature GPC determination at 140°C. It should be noted that the standard curve was prepared using standard polystyrene products manufactured by Tosoh Corporation, with product numbers: 0005204, 0005205, 0005206, 0005207, 0005208, 0005209, 0005210, 0005211, 0005212, 0005213, 0005214, 0005215, 0005218, 0005220, and 0005221. Therefore, the obtained values ​​are the converted molecular weights of polystyrene.

[0148] [Structural Analysis of Polyethylene Resin (B)]

[0149] Weigh each polyethylene resin separately and dissolve it in deuterated o-dichlorobenzene solvent at 130°C. Use the dissolved sample to determine its concentration at 120°C. 13 C10 NMR spectrum. It should be noted that, regarding the chemical shift benchmark, the signal of the main chain of polyethylene resin is set to 30.0 ppm.

[0150] Using the monolayer films obtained in Examples 1-5 and Comparative Examples 1-3, the following total haze and impact strength were evaluated. The results are shown in Table 1 below.

[0151] [Evaluation of total haze]

[0152] The total haze of the monolayer film was measured using a haze meter (NDH4000, manufactured by Nippon Denshoku Kogyo Co., Ltd.). The lower the value, the better the transparency.

[0153] [Evaluation of impact intensity (dart impact)]

[0154] Using a dart impact testing machine (manufactured by Toyo Seiki Co., Ltd.), a 38mm, 32g dart made of phenolic plastic was subjected to a weight and dropped from a height of 0.66m onto a monolayer film. The appearance of the monolayer film after the dart was dropped was visually confirmed, and the maximum weight at which damage was not confirmed was defined as the dart impact strength of the monolayer film.

[0155] [Table 1]

[0156]

[0157] Based on the results in Table 1 above, Examples 1 to 5 obtained using a specific polyethylene resin (B) exhibit superior transparency and impact strength compared to Comparative Examples 1 and 2 obtained using polyethylene resins that do not contain structural units derived from 1-hexene and / or 1-octene.

[0158] In addition, the overall haze of Comparative Example 3 was deteriorated when using a polyethylene resin that contained structural units derived from 1-hexene and / or 1-octene but whose weight-average molecular weight was outside a certain range, thus failing to balance transparency and mechanical properties.

[0159] The above embodiments illustrate specific aspects of the present invention, but these embodiments are merely illustrative and not intended to be limiting. Various modifications that are obvious to those skilled in the art should be considered to fall within the scope of the present invention.

[0160] Industrial availability

[0161] This resin composition has excellent transparency and impact strength. Therefore, in addition to general food products, it can also be used as a packaging material for various packaging containers and packaging films for condiments such as mayonnaise and sauces, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

Claims

1. A resin composition comprising an ethylene-vinyl alcohol copolymer A, a polyethylene resin B, and a polyolefin resin C having polar groups. The polyethylene resin B contains structural units derived from 1-hexene and / or 1-octene. The weight-average molecular weight of the polyethylene resin B is above 230,000. The melt flow rate of the polyolefin resin C with polar groups, measured according to JIS K7210:2014 at 190°C and a load of 2160g, is 0.15 to 50 g / 10 minutes.

2. The resin composition according to claim 1, wherein, The content ratio of ethylene-vinyl alcohol copolymer A to polyethylene resin B, A / B, is 40 / 60 to 0.1 / 99.9 by mass.

3. The resin composition according to claim 1 or 2, wherein, The content of structural units derived from 1-hexene and / or 1-octene in the polyethylene resin B is 2.0 mol% or more.

4. The resin composition according to claim 1 or 2, wherein, The density of the polyethylene resin B is 0.850–0.920 g / cm³. 3 .

5. A multilayer structure having at least one layer comprising the resin composition of claim 1 or 2.

6. A film comprising the resin composition of claim 1 or 2.

7. A packaging material comprising the resin composition of claim 1 or 2.

8. A pouch comprising the resin composition of claim 1 or 2.

9. A secondary molded article comprising the resin composition of claim 1 or 2.

10. A method for manufacturing a resin composition, comprising the method for manufacturing the resin composition according to claim 1 or 2. The method includes a step of mixing the ethylene-vinyl alcohol copolymer A, polyethylene resin B, and polyolefin resin C having polar groups.

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