Resin pellet group and laminate structure using the same

Abstract

The resin pellet group of the present invention comprises pellet (A1) containing ethylene-vinyl alcohol copolymer (a1) and pellet (A2) containing ethylene-vinyl alcohol copolymer (a2). Among them, the melt flow rate of pellet (A1) measured at 210 °C under a load of 2160 g in accordance with JIS K7210:2014 is 2 g / 10 min or more and less than 11 g / 10 min, and the melt flow rate of pellet (A2) measured at 210 °C under a load of 2160 g in accordance with JIS K7210:2014 is 11 g / 10 min or more and 40 g / 10 min or less. The ethylene unit content (EC a1 ) of ethylene-vinyl alcohol copolymer (a1) is different from the ethylene unit content (EC a2 ) of ethylene-vinyl alcohol copolymer (a2), and the mass ratio (A1 / A2) of pellet (A1) to pellet (A2) is 20 / 80 or more and 99 / 1 or less. The resin pellet group of the present invention is used by direct melt molding.

Description

Technical Field

[0001] The present invention relates to a resin pellet group and a laminated structure using the same. Background Art

[0002] Generally, ethylene-vinyl alcohol copolymer (hereinafter referred to as "EVOH") has excellent transparency, gas barrier property, aroma retention property, solvent resistance, oil resistance, etc. Utilizing such characteristics, EVOH is used as a packaging material for foods, pharmaceuticals, industrial chemicals, pesticides, etc. in films, sheets, containers, etc. In addition, EVOH is also used in applications such as fuel tanks of vehicles such as automobiles, inner tube materials, agricultural films, geomembranes, and insole materials by utilizing its barrier property, heat insulation property, stain resistance property, etc.

[0003] However, EVOH has multiple hydroxyl groups in the molecule, has high crystallinity and crystallization rate, and lacks flexibility. Therefore, it is pointed out that the secondary processing adaptability, especially the heat stretching property, is low when formed into packaging materials for foods, etc.

[0004] As a method for solving this problem, Patent Document 1 proposes a multilayer structure obtained by laminating a layer formed of two types of EVOH having different melting points and a polypropylene layer with an adhesive resin layer in order to improve the stretching property.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Laid-Open No. 2000-318095 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] However, in the multilayer structure of Patent Document 1, particularly in the peel strength between the EVOH layer and the adhesive layer after forming a container or the like by heat stretching forming, unevenness between products is likely to occur, and the quality stability sometimes becomes insufficient.

[0010] The subject of the present invention is to solve the above problems, and an object thereof is to provide a resin pellet group capable of obtaining a molded body having excellent gas barrier property and secondary processability and excellent stability of peel strength after secondary processing, a laminated structure, a packaging material, and a container using the same.

[0011] Means for Solving the Problems

[0012] That is, the present invention is achieved by providing the following technical solutions.

[0013] [1] A resin pellet group for direct melt forming, wherein,

[0014] It contains pellets (A1) containing EVOH (a1) and pellets (A2) containing EVOH (a2).

[0015] The melt flow rate (hereinafter also referred to as "MFR") of the pellets (A1) at 210 °C under a load of 2160 g measured according to JIS K7210:2014 is 2 g / 10 min or more and less than 11 g / 10 min, and the MFR of the pellets (A2) at 210 °C under a load of 2160 g measured according to JIS K7210:2014 is 11 g / 10 min or more and 40 g / 10 min or less.

[0016] The ethylene unit content (EC a1 ) of the EVOH (a1) is different from the ethylene unit content (EC a2 ) of the EVOH (a2).

[0017] The mass ratio (A1 / A2) of the pellets (A1) to the pellets (A2) is 20 / 80 or more and 99 / 1 or less.

[0018] [2] The resin pellet group according to [1], wherein the absolute value of the difference between the ethylene unit content (EC a1 ) of the EVOH (a1) and the ethylene unit content (EC a2 ) of the EVOH (a2) is 4 mol% or more.

[0019] [3] The resin pellet group according to [1] or [2], wherein the ethylene unit content (EC a2 ) of the EVOH (a2) is greater than the ethylene unit content (EC a1 ) of the EVOH (a1).

[0020] [4] The resin pellet group according to any one of [1] to [3], wherein the ethylene unit content (EC a1 ) of the EVOH (a1) is 20 mol% or more and 50 mol% or less, and the ethylene unit content (EC a2 ) of the EVOH (a2) is 30 mol% or more and 60 mol% or less.

[0021] [5] The resin pellet group according to any one of [1] to [4], wherein the difference between the melting point of the pellets (A1) and the melting point of the pellets (A2) is 8 °C or more and 35 °C or less.

[0022] [6] A layer structure, which has a gas barrier layer, and the gas barrier layer is directly melt-formed from the resin pellet group according to any one of [1] to [5].

[0023] [7] The layer structure according to [6], wherein at least one surface of the gas barrier layer is provided with a thermoplastic resin layer.

[0024] [8] The layer structure according to [7], which has a coextrusion structure of the gas barrier layer and the thermoplastic resin layer.

[0025] [9] A packaging material, which contains the layer structure according to any one of [6] to [8].

[0026]

[10] A container, which contains the layer structure according to any one of [6] to [8].

[0027]

[11] A method for manufacturing a layer structure, which includes:

[0028] A step of directly melt-molding a resin pellet group containing a pellet (A1) containing an ethylene-vinyl alcohol copolymer (a1) and a pellet (A2) containing an ethylene-vinyl alcohol copolymer (a2) to form a gas barrier layer,

[0029] The melt flow rate of the pellet (A1) at 210 °C and a load of 2160 g measured according to JIS K7210:2014 is 2 g / 10 minutes or more and less than 11 g / 10 minutes,

[0030] The melt flow rate of the pellet (A2) at 210 °C and a load of 2160 g measured according to JIS K7210:2014 is 11 g / 10 minutes or more and 40 g / 10 minutes or less,

[0031] The ethylene unit content (EC a1 ) of the ethylene-vinyl alcohol copolymer (a1) and the ethylene unit content (EC a2 ) of the ethylene-vinyl alcohol copolymer (a2) are different, and

[0032] The mass ratio (A1 / A2) of the pellet (A1) to the pellet (A2) is 20 / 80 or more and 99 / 1 or less.

[0033] Effects of the Invention

[0034] According to the present invention, a resin pellet group capable of obtaining a molded body having excellent gas barrier properties and secondary processability and excellent stability of peel strength after secondary processing, and a layer structure, a packaging material, and a container obtained by using the same can be provided. Description of the Drawings

[0035] Figure 1 Schematic diagram of the twin-screw extruder used in Production Example 9.

[0036] Figure 2 Schematic diagram of the hot cutter used in Production Example 9.​​ Detailed implementation mode

[0037] (Resin pellet group)

[0038] The resin pellet group of the present invention comprises pellets (A1) containing EVOH (a1) and pellets (A2) containing EVOH (a2). The MFR of the pellets (A1) at 210 °C under a load of 2160 g measured according to JIS K7210:2014 is 2 g / 10 min or more and less than 11 g / 10 min. The MFR of the pellets (A2) at 210 °C under a load of 2160 g measured according to JIS K7210:2014 is 11 g / 10 min or more and 40 g / 10 min or less. The ethylene unit content (EC a1 ) of the ethylene-vinyl alcohol copolymer (a1) is different from the ethylene unit content (EC a2 ) of the ethylene-vinyl alcohol copolymer (a2). The mass ratio (A1 / A2) of the pellets (A1) to the pellets (A2) is 20 / 80 or more and 99 / 1 or less. By making the pellet group of the present invention satisfy the above conditions, a molded body (such as a laminated structure) that maintains the gas barrier property originally possessed by EVOH and has excellent secondary processability can be provided. Furthermore, surprisingly, the stability of the peel strength after secondary processing of the molded body is excellent. Here, the "stability of the peel strength after secondary processing" means that, for example, when a gas barrier layer directly melt-molded from the resin pellet group of the present invention is laminated with a layer using other materials, the peel strength between the gas barrier layer and the layer using other materials after secondary processing of the laminate is stable. If the stability of the peel strength after secondary processing is good, unevenness in the quality of the product obtained by secondary processing is suppressed. In addition, by having pellets containing EVOH with different ethylene unit contents, a tendency to maintain the gas barrier property and have excellent secondary processability is exhibited. By being a resin pellet group comprising pellets (A1) and pellets (A2) having specific MFRs, a tendency for excellent stability of the peel strength after secondary processing is exhibited.

[0039] Here, in this specification, a "resin pellet group" refers to an aggregate of resin pellets. Therefore, the resin pellet group of the present invention is an aggregate of resin pellets in which the pellets include the (A1) and the pellets (A2). The resin pellet group of the present invention is preferably a dry blend comprising the pellets (A1) and the pellets (A2). Here, in this specification, a "dry blend" refers to a state in which the respective pellets constituting the resin pellet group are sufficiently mixed with each other. For example, the sizes of the respective resin pellets constituting the resin pellet group are not particularly limited. The minimum unit of the resin pellet group is a dry blend composed of a combination of one certain resin pellet and one other type of resin pellet.

[0040] Both EVOH (a1) and EVOH (a2) contained in pellet (A1) and pellet (A2) are copolymers obtained, for example, by saponifying an ethylene-vinyl ester copolymer. The production and saponification of the ethylene-vinyl ester copolymer can be carried out by a known method as described later. Examples of the vinyl ester used in this method include fatty acid vinyl esters such as vinyl acetate, vinyl formate, vinyl propionate, vinyl pivalate, and vinyl versatate.

[0041] The ethylene unit content (EC a1 ) of EVOH (a1) is different from the ethylene unit content (EC a2 ) of EVOH (a2). The absolute value of the difference between the ethylene unit content (EC a1 ) and the ethylene unit content (EC a2 ), i.e., |EC a1 - EC a2 |, is preferably 4 mol% or more, more preferably 7 mol% or more, still more preferably 10 mol% or more, and even more preferably 13 mol% or more. In addition, the absolute value of the difference in the ethylene unit content mentioned above (|EC a1 - EC a2 |) is preferably 20 mol% or less, more preferably 18 mol%. If the absolute value of the difference in the ethylene unit content (|EC al - EC a2 |) is within the above range, there is a tendency to achieve a balance between secondary processability and gas barrier properties. The ethylene unit content (ECa2) is preferably greater than the ethylene unit content (ECa1). By making the ethylene unit content (ECa2) greater than the ethylene unit content (EC a1 ), it is easier to obtain pellets having the target MFR.

[0042] The ethylene unit content (EC a1 ) is preferably 20 mol% or more and 50 mol% or less, more preferably 22 mol% or more and 44 mol% or less, still more preferably 24 mol% or more and 35 mol% or less. In contrast, the ethylene unit content (EC a2 ) is preferably 30 mol% or more and 60 mol% or less, more preferably 35 mol% or more and 55 mol% or less, still more preferably 40 mol% or more and 50 mol% or less. If the ethylene unit content (EC a1 ) and the ethylene unit content (EC a2 ) are respectively within the above ranges, there is a tendency to achieve a balance between secondary processability and gas barrier properties. The ethylene unit content (EC a1 ) of EVOH (a1) and the ethylene unit content (EC a2 ) of EVOH (a2) can both be measured by, for example, nuclear magnetic resonance (NMR) method.

[0043] Furthermore, in the resin pellet group of the present invention, the saponification degrees of EVOH (a1) and EVOH (a2) (i.e., the saponification degrees of the vinyl ester components of EVOH (a1) and EVOH (a2)) are, for example, preferably 85 mol% or more, more preferably 90 mol% or more, further preferably 95 mol% or more, and particularly preferably 99 mol%. On the other hand, the saponification degrees of EVOH (a1) and EVOH (a2) are, for example, preferably 100 mol% or less, and may be 99.99 mol% or less. When the saponification degrees of EVOH (a1) and EVOH (a2) are within the above ranges, the resin pellet group of the present invention can have appropriate thermal stability. The above saponification degree can be determined by 1 measuring the peak areas of the hydrogen atoms contained in the vinyl ester unit and the hydrogen atoms contained in the vinyl alcohol unit by 1H-NMR measurement and calculating.

[0044] EVOH (a1) and / or EVOH (a2) may also have units derived from monomers other than ethylene, vinyl esters, and their saponified products within the scope that does not impair the object of the present invention. When EVOH (a1) and / or EVOH (a2) has other monomer units, the content of the other monomer units relative to all the structural units of EVOH (a1) and / or EVOH (a2) can be, for example, 30 mol% or less, 20 mol% or less, 10 mol% or less, or 5 mol% or less. When EVOH (a1) and / or EVOH (a2) has units derived from the other monomer, the content can be, for example, 0.05 mol% or more, and can also be 0.1 mol% or more.

[0045] As other monomers, for example, olefins such as propylene, butene, pentene, and hexene can be cited; olefins containing an ester group such as 3-acetyloxy-1-propene, 3-acetyloxy-1-butene, 4-acetyloxy-1-butene, 3,4-diacetyloxy-1-butene, 3-acetyloxy-4-methyl-1-butene, 4-acetyloxy-1-butene, 3,4-diacetyloxy-1-butene, 3-acetyloxy-4-methyl-1-butene, 4-acetyloxy-2-methyl-1-butene, 4-acetyloxy-3-methyl-1-butene, 3,4-diacetyloxy-2-methyl-1-butene, 4-acetyloxy-1-pentene, 5-acetyloxy-1-pentene, 4,5-diacetyloxy-1-pentene, 4-acetyloxy-1-hexene, 5-acetyloxy-1-hexene, 6-acetyloxy-1-hexene, 5,6-diacetyloxy-1-hexene, 1,3-diacetyloxy-2-methylenepropane or their saponified products; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid or their acid anhydrides, salts, or monoalkyl esters or dialkyl esters, etc.; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefin sulfonic acids such as vinylsulfonic acid, allylsulfonic acid, and methallylsulfonic acid or their salts; vinylsilane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxy-ethoxy)silane, and γ-methacryloyloxypropylmethoxysilane; alkyl vinyl ethers, vinyl ketones, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, etc.

[0046] EVOH(a1) and / or EVOH(a2) can be modified by urethanation, acetalization, cyanoethylation, oxyalkylation, etc. as needed.

[0047] EVOH(a1) and EVOH(a2) can be obtained by known methods such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc. In one embodiment, a bulk polymerization method or a solution polymerization method capable of polymerizing in a solvent-free or solution such as alcohol is used.

[0048] The solvent used in the solution polymerization method is not particularly limited. For example, it is alcohol, preferably lower alcohols such as methanol, ethanol, and propanol. The amount of the solvent used in the polymerization reaction solution can be selected by considering the viscosity-average degree of polymerization of the target EVOH and the chain transfer of the solvent. The mass ratio of the solvent contained in the reaction solution to all monomers (solvent / all monomers) is, for example, 0.01 to 10, preferably 0.05 to 3.

[0049] Examples of the catalyst used in the above polymerization include azo initiators such as 2,2-azobisisobutyronitrile, 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2-azobis(2-cyclopropylpropionitrile); organic peroxide initiators such as isobutyryl peroxide, cumyl peroxyneodecanoate, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, tert-butyl peroxyneodecanoate, lauroyl peroxide, benzoyl peroxide, tert-butyl hydroperoxide, etc. The amount of the catalyst used in the polymerization is preferably 0.005 to 0.6 equivalents relative to the vinyl ester component used in the polymerization.

[0050] The polymerization temperature is preferably 20°C to 90°C, more preferably 40°C to 70°C. The polymerization time is preferably 2 hours to 15 hours, more preferably 3 hours to 11 hours. The polymerization rate is preferably 10% to 90% relative to the vinyl ester charged, more preferably 30% to 80%. The resin content in the polymerized solution is preferably 5% to 85%, more preferably 20% to 70%.

[0051] In the above polymerization, after the polymerization for a specified time or at a specified polymerization rate, a polymerization inhibitor is added as needed, unreacted ethylene gas is evaporated and removed, and unreacted vinyl ester is removed, whereby an ethylene-vinyl ester copolymer solution is obtained.

[0052] An alkali catalyst is added to the above copolymer solution to saponify the copolymer. The saponification method can be either a continuous type or a batch type, for example. Examples of the alkali catalyst that can be added include sodium hydroxide, potassium hydroxide, alkali metal alkoxides, etc.

[0053] The EVOH after the saponification reaction contains by-product salts such as alkali catalysts, sodium acetate, potassium acetate, and other impurities. Therefore, it is preferably removed by neutralization and washing. Here, when the EVOH after the saponification reaction is washed with water (such as ion-exchanged water) that substantially does not contain specified ions (such as metal ions, chloride ions), a part of the by-product salts such as sodium acetate and potassium acetate may remain and not be completely removed. Thereafter, by drying it, EVOH (a1) and EVOH (a2) can be synthesized respectively.

[0054] In the resin pellet group of the present invention, pellet (A1) and pellet (A2) each independently have a specified MFR.

[0055] Specifically, for the pellet (A1), the MFR at 210°C and a load of 2160 g measured in accordance with JIS K7210:2014 is 2 g / 10 min or more and less than 11 g / 10 min, preferably 3 g / 10 min or more and 9.5 g / 10 min or less, more preferably 3.5 g / 10 min or more and 9 g / 10 min or less. Here, if the MFR at 210°C and a load of 2160 g is less than 2 g / 10 min, poor kneading will occur during melt forming and the secondary processability will decrease. If the MFR at 210°C and a load of 2160 g is 11 g / 10 min or more, the non-uniformity of the peel strength after secondary processing will increase.

[0056] On the other hand, for the pellet (A2), the MFR at 210°C and a load of 2160 g measured in accordance with JIS K7210:2014 is 11 g / 10 min or more and 40 g / 10 min or less, preferably 12 g / 10 min or more and 30 g / 10 min or less, more preferably 12.5 g / 10 min or more and 20 g / 10 min or less. Here, if the MFR at 210°C and a load of 2160 g is less than 11 g / 10 min, the non-uniformity of the peel strength after secondary processing will increase. If the MFR at 210°C and a load of 2160 g exceeds 40 g / 10 min, poor kneading will occur during melt forming and the secondary processability will decrease.

[0057] The difference (A2 - A1) between the MFR of the pellet (A2) at 210°C and a load of 2160 g measured in accordance with JIS K7210:2014 and the MFR of the pellet (A1) at 210°C and a load of 2160 g measured in accordance with JIS K7210:2014 is preferably 1.0 g / 10 min or more, more preferably 3 g / 10 min or more, further preferably 7 g / 10 min or more, and sometimes also preferably 10 g / 10 min or more. In addition, the aforementioned MFR difference (A2 - A1) is preferably 30 g / 10 min or less, may be 20 g / 10 min or less, or may be 1530 g / 10 min or less. If the aforementioned MFR difference (A2 - A1) is within the above range, there is a tendency for excellent secondary processability, stability of the peel strength after secondary processing, and ejection stability.

[0058] In the present invention, the difference in melting point between the pellet (A1) and the pellet (A2) is preferably 8°C or more and 35°C or less, more preferably 10°C or more and 30°C or less. If the difference in melting point between the pellet (A1) and the pellet (A2) is 8°C or more, there is a tendency for excellent secondary processability. If the difference in melting point between the pellet (A1) and the pellet (A2) is 35°C or less, there is a tendency for excellent ejection stability.

[0059] It should be noted that the melting point of the above-mentioned pellet (A1) in the present invention is preferably 160°C to 200°C, more preferably 175°C to 196°C. On the other hand, the melting point of the above-mentioned pellet (A2) is preferably 135°C to 186°C, more preferably 145°C to 175°C, and further preferably 150°C to 170°C. If the melting points of pellet (A1) and pellet (A2) are within the above ranges, a tendency to balance secondary processability and gas barrier properties can be presented.

[0060] The MFR of pellet (A1) and pellet (A2) can be adjusted by, for example, the ethylene unit content and saponification degree of EVOH (a1) and EVOH (a2), as well as the polymerization time, polymerization catalyst amount, polymerization temperature, etc. during the synthesis of EVOH (a1) and EVOH (a2). In addition, it can also be adjusted by the content of the boron compound described later.

[0061] Pellets (A1) and (A2) can each independently contain other components such as other thermoplastic resins, metal salts, acids, boron compounds, plasticizers, fillers, anti-blocking agents, lubricants, stabilizers, surfactants, colorants, ultraviolet absorbers, antistatic agents, desiccants, crosslinking agents, various fibers and other reinforcing materials, etc. outside EVOH (a1) and EVOH (a2) within the range that does not impair the effects of the present invention.

[0062] Examples of the above-mentioned other thermoplastic resins include various polyolefins (polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, copolymer of ethylene and α-olefin with 4 or more carbon atoms, copolymer of polyolefin and maleic anhydride, ethylene-vinyl ester copolymer, ethylene-acrylate copolymer, or modified polyolefin obtained by graft-modifying them with unsaturated carboxylic acid or its derivative, etc.), various polyamides (nylon 6, nylon 6·6, nylon 6 / 66 copolymer, nylon 11, nylon 12, polyhexamethylene isophthalamide, etc.), various polyesters (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylonitrile, polyurethane, polycarbonate, polyacetal, polyacrylate, and modified polyvinyl alcohol resin, etc. It should be noted that from the viewpoint of good recyclability, the pellet group of the present invention preferably does not contain 20 mass parts or more of various polyamides, more preferably does not contain 13 mass parts or more, further preferably does not contain 5 mass parts or more, and even more preferably the pellet group of the present invention substantially does not contain various polyamides, and particularly preferably the pellet group of the present invention does not contain various polyamides.

[0063] From the viewpoint of improving thermal stability, the above metal salts are preferably alkali metal salts, more preferably alkaline earth metal salts. When the pellet (A1) and / or (A2) contains a metal salt, the lower limit of its content is preferably 1 ppm or more, 5 ppm or more, 10 ppm or more, or 20 ppm or more in terms of the metal atom of the metal salt based on the reference pellet (A1) or (A2). When the pellet (A1) and / or (A2) contains a metal salt, the upper limit of its content is preferably 10000 ppm or less, 5000 ppm or less, 1000 ppm or less, or 500 ppm or less in terms of the metal atom of the metal salt based on the reference pellet (A1) or (A2). When the content of the metal salt is within the above range, the thermal stability and hue of the pellet (A1) and / or (A2) during melt forming become good.

[0064] From the viewpoint of being able to improve the thermal stability during melt forming of the pellets (A1) and (A2), the above acid is preferably a carboxylic acid compound, a phosphoric acid compound, etc. When the pellet (A1) and / or (A2) contains a carboxylic acid compound, its content is preferably 1 ppm or more, more preferably 10 ppm or more, and further preferably 50 ppm or more. On the other hand, the content of the carboxylic acid compound is preferably 10000 ppm or less, more preferably 1000 ppm or less, and further preferably 500 ppm or less. When the pellet (A1) and / or (A2) contains a phosphoric acid compound, the content in terms of phosphate radical is preferably 1 ppm or more, more preferably 10 ppm or more, and further preferably 30 ppm or more. On the other hand, the content in terms of phosphate radical of the phosphoric acid compound is preferably 10000 ppm or less, more preferably 1000 ppm or less, and further preferably 300 ppm or less. When the content of the carboxylic acid compound or the phosphoric acid compound is within the above range, the thermal stability and hue of the pellet (A1) and / or (A2) during melt forming become good.

[0065] When the pellet (A1) and / or (A2) contains the above boron compound, its content is preferably 1 ppm or more, more preferably 10 ppm or more, and further preferably 50 ppm or more. On the other hand, the content of the boron compound is preferably 2000 ppm or less, more preferably 1000 ppm or less, and further preferably 500 ppm or less. When the content of the boron compound is within the above range, there is a tendency that the thermal stability of the pellet (A1) and / or (A2) during melt forming becomes good. In addition, when a boron compound is added, there is a tendency for the MFR to increase.

[0066] The method for making the pellets (A1) and / or (A2) contain the above other components is not particularly limited. For example, a composition containing the above EVOH (a1) or EVOH (a2) can be added during pelletization (i.e., when manufacturing the pellets (A1) and / or (A2)) and kneaded. As the method for adding during the manufacture of the pellets (A1) and / or (A2), the following can also be cited: a method of adding in the form of a dry powder; a method of adding in the state of a paste impregnated with a specified solvent; a method of adding in the state of being suspended in a specified liquid; a method of adding in the form of a solution by dissolving it in a specified solvent; a method of impregnating it in a specified solution, etc. It should be noted that when the method of impregnating it in a specified solution is used, kneading may not be performed. Among them, from the viewpoint of being able to uniformly disperse these compounds in EVOH, a method of adding and kneading in the form of a solution by dissolving it in a specified solvent and a method of impregnating it in a specified solution are preferred. The specified solvent is not particularly limited, and from the viewpoints of the solubility of the added compound, cost, ease of handling, and safety of the working environment, water is preferred.

[0067] From the viewpoint of further exerting the effects of the present invention, the proportion of EVOH (a1) in the pellets (A1) is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 97% by mass or more, and particularly preferably 99% by mass or more. The pellets (A1) can consist essentially of only EVOH (a1). In addition, the proportion of EVOH (a2) in the pellets (A2) is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 97% by mass or more, and particularly preferably 99% by mass or more. The pellets (A1) can consist essentially of only EVOH (a2). In addition, the total content of EVOH (a1) and EVOH (a2) in the resin pellet group of the present invention is preferably more than 95% by mass relative to the total mass, more preferably 97% by mass or more, and still more preferably 99% by mass or more.

[0068] In the resin pellet group of the present invention, pellets (A1) and pellets (A2) are contained in a specified mass ratio (A1 / A2). Specifically, the mass ratio (A1 / A2) of pellets (A1) to pellets (A2) is 20 / 80 or more and 99 / 1 or less, preferably 50 / 50 or more and 93 / 7 or less, more preferably 70 / 30 or more and 87 / 13 or less. If the mass ratio (A1 / A2) is less than 20 / 80 (that is, when the content of pellets (A1) is less than 20 parts by mass relative to 80 parts by mass of pellets (A2)), the gas barrier property decreases. If the mass ratio (A1 / A2) exceeds 99 / 1 (that is, when the content of pellets (A2) is less than 1 part by mass relative to 99 parts by mass of pellets (A1)), the secondary processability decreases. When the mass ratio (A1 / A2) of the above-mentioned pellets (A1) and pellets (A2) is within the above range, a molded article having excellent gas barrier property and excellent secondary processability can be obtained using the resin pellet group of the present invention.

[0069] The pellet group of the present invention may contain pellets other than pellets (A1) and pellets (A2). The proportion of pellets (A1) and pellets (A2) in the resin pellet group of the present invention is preferably 90% by mass or more, more preferably 96% by mass or more, further preferably 98% by mass or more, and particularly preferably 99% by mass or more. The pellet group of the present invention may consist essentially of only pellets (A1) and pellets (A2), and the pellet group of the present invention may also consist of only pellets (A1) and pellets (A2).

[0070] When obtaining a desired molded article, the resin pellet group of the present invention is directly used for melt molding. Here, the term "directly" in the term "directly perform melt molding" used in this specification means that the contents of the resin pellet group of the present invention, that is, pellets (A1) and (A2), are not pre-melt-kneaded and pelletized in advance, and in order to obtain a desired resin molded article, pellets (A1) and (A2) are directly used for manufacturing a resin molded article in a state of maintaining the pellet form (that is, the dry blend state of pellets (A1) and (A2)). In addition, the term "resin molded article" used in this specification includes a molded article obtained by secondary processing (molding) using resin pellets, and specifically refers to a molded article other than pellets.

[0071] For example, in the case of pre-melt-kneading pellets (A1) and (A2) to produce a melt-kneaded pellet and obtaining a molded article using the melt-kneaded pellet, uneven peeling strength after secondary processing occurs. In contrast, if the resin pellet group of the present invention is melt-kneaded in a dry blend state of pellets (A1) and (A2) and used for manufacturing a specified molded article (melt molded article), surprisingly, a molded article having excellent stability of peeling strength after secondary processing can be obtained.

[0072] (Layered structure)

[0073] The layer structure of the present invention is a structure composed of one or more layers, which includes a gas barrier layer formed by directly melt-molding the resin pellet group of the present invention. From the perspective of further improving the gas barrier property (such as oxygen barrier property), the number of gas barrier layers in the layer structure can be either one layer or multiple layers, and the materials constituting each gas barrier layer can be the same or different. The gas barrier layer is a layer having the function of preventing gas permeation. For example, the oxygen permeability measured according to JIS K7126 (isobaric method) under the conditions of 20 °C and 65% RH is 100 cm 3 ·20 μm / (m 2 ·day·atm) or less, preferably 50 cm 3 ·20 μm / (m 2 ·day·atm) or less, more preferably 10 cm 3 ·20 μm / (m 2 ·day·atm) or less. Here, the "100 cm 3 ·20 μm / (m 2 ·day·atm)" oxygen permeability refers to the oxygen permeation amount of 100 cm per 1 m of a 20-μm-thick film 2 and in one atmosphere of oxygen in one day 3 .

[0074] The number of layers of the layer structure of the present invention can be one layer, preferably two or more layers. In addition, the number of layers of the layer structure of the present invention can be 13 layers or less. If the number of layers of the layer structure of the present invention is within the above range, there is a tendency for good mechanical strength.

[0075] In the present invention, the average thickness of each layer of the gas barrier layer formed by directly melt-molding the resin pellet group is not necessarily limited. For example, it is preferably 0.5 μm or more, more preferably 1 μm or more, and sometimes also preferably 3 μm or more. On the other hand, the average thickness of each layer of the gas barrier layer can be 200 μm or less, or 100 μm or less. Here, in this specification, the "average thickness" refers to the average value of the thickness measured at any five places. If the average thickness of each layer of the gas barrier layer is within the above range, there is a tendency for good durability, flexibility, and appearance characteristics of the layer structure of the present invention.

[0076] The gas barrier layer directly formed by melt-molding the resin pellet group of the present invention preferably has a matrix phase containing EVOH (a1) as a main component and a dispersed phase containing EVOH (a2) as a main component. Here, the "main component" means that the component constituting the phase exceeds 50% by mass. The proportion of EVOH (a1) in the components constituting the matrix phase is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more. The matrix phase may consist essentially of only EVOH (a1). In addition, the proportion of EVOH (a2) in the components constituting the dispersed phase is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more. The dispersed phase may consist essentially of only EVOH (a2). By making the gas barrier layer have such a matrix phase and a dispersed phase, it is possible to balance secondary processability and gas barrier properties, and the stability of the peel strength after secondary processing is good. In the present invention, when the gas barrier layer has the above matrix phase and dispersed phase, the dispersed phase preferably exists in the form of particles having an average particle diameter of 200 nm or more and 1.0 μm or less, more preferably 220 nm or more and 750 nm or less, still more preferably 240 nm or more and 500 nm or less. If the average particle diameter of the particles constituting the dispersed phase is 200 nm or more, there is a tendency for the stability of the peel strength after secondary processing to be excellent. If the average particle diameter of the particles constituting the dispersed phase is 1.0 μm or less, there is a tendency for secondary processability and gas barrier properties to be balanced.

[0077] The average particle diameter of the particles constituting the above dispersed phase can be adjusted by, for example, adjusting the mixing ratio of EVOH (A1) and EVOH (A2) and the kneading conditions. As a specific method for adjusting the kneading conditions, in the case of using, for example, a single-screw extruder, methods such as adjusting the resin residence time or the shear viscosity according to the screw shape and the groove depth can be cited. As the screw shape, for example, a full-flight screw, a barrier screw, etc. can be used. In order to adjust the kneading strength, a screw having a shape such as Maddock or Dulmadge can be used. Further, in order to increase the shear rate, the screw rotation speed can be adjusted. In addition, from the viewpoint of being able to easily change the screw shape, a twin-screw extruder is sometimes used. In the case of using a twin-screw extruder, in order to adjust the kneading strength, methods such as adjusting the length of the kneading disk can be cited.

[0078] In the case of using a single-screw extruder, as specific kneading conditions, for example, the lower limit of the shear rate r of the metering section in the melt extruder calculated by the following general formula (1) is preferably 10 s -1 , more preferably 15 s -1 , particularly preferably 20 s -1In addition, the upper limit of the shear rate r is preferably 100 seconds -1 , more preferably 95 seconds -1 , particularly preferably 90 seconds -1 . If kneading is carried out under the conditions within the above range, there is a tendency that it is easy to adjust the average particle diameter of the particles constituting the above-mentioned dispersed phase to an appropriate range and the straight-through cutting property becomes good.

[0079]

[0080] In formula (1), D represents the barrel diameter (cm), N represents the screw rotation speed (rpm), h represents the groove depth of the metering section (cm), and r represents the shear rate (seconds -1 ).

[0081] In addition to the gas barrier layer formed by directly melt-molding the above resin pellet group, the layer structure of the present invention may further include at least one other gas barrier layer. The material constituting the other gas barrier layer is not particularly limited, and examples thereof include EVOH, polyamide, polyester, polyvinylidene chloride, acrylonitrile copolymer, polyvinylidene fluoride, polychlorotrifluoroethylene, polyvinyl alcohol, inorganic vapor deposition body (for example, a vapor deposition body obtained by vapor-depositing an inorganic substance such as aluminum, tin, indium, nickel, titanium, chromium, metal oxide, metal nitride, metal oxynitride, metal carbonitride, etc. on a specified substrate), etc. Among them, from the viewpoints of melt moldability and gas barrier property, EVOH is preferred. When the other gas barrier layer is provided on the layer structure of the present invention, the thickness of the other gas barrier layer is not particularly limited, and those skilled in the art can select any thickness within the range that does not impair the functions and effects of the gas barrier layer formed by directly melt-molding the above resin pellet group.

[0082] The layer structure of the present invention may also have a thermoplastic resin layer on the basis of the above gas barrier layer.

[0083] From the viewpoint of improving impact resistance, the number of thermoplastic resin layers in the layer structure of the present invention is preferably 1 or more, more preferably 2 or more. In addition, the number of thermoplastic resin layers can be 13 or less. It should be noted that when the layer structure includes a plurality of thermoplastic resin layers, the materials constituting each layer can be the same or different.

[0084] The thermoplastic resin layer contains a thermoplastic resin as the main component. The thermoplastic resin layer may contain either a single thermoplastic resin or a mixture of multiple thermoplastic resins as the main component. The proportion of the thermoplastic resin in the thermoplastic resin layer is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 99% by mass or more. The thermoplastic resin layer may consist essentially of only the thermoplastic resin. The layer structure in the present invention can improve stretchability and thermoformability by laminating the thermoplastic resin layer having a thermoplastic resin as the main component.

[0085] The average thickness of each thermoplastic resin layer is preferably 10 μm or more, more preferably 20 μm or more. Additionally, the average thickness of each thermoplastic resin layer may be 1000 μm or less, may be 500 μm or less, and may also be 400 μm or less. If the average thickness of each thermoplastic resin layer is 10 μm or more, it is easy to adjust the thickness during lamination, and the durability of the above layer structure can be further improved. If the average thickness of one thermoplastic resin layer is 1000 μm or less, there is a tendency for good thermoformability.

[0086] The thermoplastic resin constituting the thermoplastic resin layer is not particularly limited as long as it is a resin that softens upon heating to the glass transition temperature or melting point and exhibits plasticity. Examples include polyolefin resins (such as polyethylene resins and polypropylene resins), grafted polyolefin resins obtained by graft-modifying with unsaturated carboxylic acids or their esters, halogenated polyolefin resins, ethylene-vinyl acetate copolymer resins, ethylene-acrylic acid copolymer resins, ethylene-acrylate copolymer resins, polyester resins, polyamide resins, polyvinyl chloride resins, polyvinylidene chloride resins, acrylic resins, polystyrene resins, vinyl ester resins, ionomers, polyester elastomers, polyurethane elastomers, aromatic or aliphatic polyketones, etc. In particular, from the reasons of good mechanical strength and formability, polyolefin resins are preferred, and polyethylene resins and polypropylene resins are more preferred.

[0087] The thermoplastic resin layer may contain additives within the range that does not impair the object of the present invention. Examples of the additives include resins other than the above thermoplastic resins, heat stabilizers, ultraviolet absorbers, antioxidants, colorants, fillers, etc. When the thermoplastic resin layer contains additives, the content rate of the additives is preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less, relative to the total amount of the thermoplastic resin layer.

[0088] In the layer structure of the present invention, the thermoplastic resin layer is preferably disposed on at least one surface of the above gas barrier layer. Here, "disposed on one surface" means that the thermoplastic resin layer can be directly laminated with the above gas barrier layer or can be laminated via an adhesive layer. By disposing the thermoplastic resin layer in this way, there is a tendency for the mechanical strength to be improved.

[0089] The layer structure of the present invention preferably also has a coextrusion structure of the above-mentioned gas barrier layer and the thermoplastic resin. The term "coextrusion structure of the gas barrier layer and the thermoplastic resin" used in this specification refers to a laminated structure formed by coextruding the above-mentioned gas barrier layer and the thermoplastic resin layer. By having such a coextrusion structure, there is a tendency for the mechanical strength to be improved.

[0090] Furthermore, the layer structure of the present invention may include at least one adhesive layer. The adhesive layer can be disposed, for example, between the above-mentioned gas barrier layer and the thermoplastic resin layer. The number of adhesive layers included in the layer structure is not particularly limited. By providing the layer structure of the present invention with an adhesive layer, the interlayer adhesiveness between the gas barrier layer and the thermoplastic resin layer can be improved. It should be noted that when multiple adhesive layers are included in the layer structure of the present invention, the materials constituting each layer may be the same or different.

[0091] As the material constituting the adhesive layer, a known adhesive resin can be used. In addition, the material constituting the adhesive layer can be appropriately selected by those skilled in the art according to the manufacturing method of the layer structure.

[0092] For example, in the case of manufacturing the layer structure of the present invention by a lamination method, a two-component reactive polyurethane-based adhesive obtained by mixing and reacting a polyisocyanate component and a polyol component can be used in the adhesive layer. In addition, by adding a small amount of additives such as a known silane coupling agent to the adhesive layer, the adhesiveness can be further improved.

[0093] Alternatively, in the case of manufacturing the layer structure of the present invention by coextrusion molding, the material used in the adhesive layer is not particularly limited as long as it has adhesiveness to the gas barrier layer and the thermoplastic resin layer, and an adhesive resin containing a carboxylic acid-modified polyolefin can be used, for example. As the carboxylic acid-modified polyolefin, a carboxyl group-containing modified olefin polymer obtained by chemically bonding (e.g., addition reaction, graft reaction, etc.) an ethylenically unsaturated carboxylic acid, its ester, or its anhydride to an olefin polymer is preferably used. Here, examples of the olefin polymer include polyolefins such as polyethylene (e.g., low-pressure polyethylene, medium-pressure polyethylene, high-pressure polyethylene), linear low-density polyethylene, polypropylene, and polybutene; copolymers of olefins and other monomers (e.g., vinyl esters, unsaturated carboxylic acid esters, etc.) (e.g., ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc.). Linear low-density polyethylene, ethylene-vinyl acetate copolymer (the content of vinyl acetate is 5 to 55% by mass), and ethylene-ethyl acrylate copolymer (the content of ethyl acrylate is 8 to 35% by mass) are preferred, and linear low-density polyethylene and ethylene-vinyl acetate copolymer are particularly preferred. As the ethylenically unsaturated carboxylic acid, its ester, or its anhydride, an ethylenically unsaturated monocarboxylic acid or its ester, an ethylenically unsaturated dicarboxylic acid, or its monoester or diester, or its anhydride can be mentioned, and an ethylenically unsaturated dicarboxylic anhydride is preferred. As specific examples, maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, monomethyl maleate, monoethyl maleate, diethyl maleate, monomethyl fumarate, etc. can be mentioned, and maleic anhydride is particularly preferred.

[0094] The addition amount or graft amount (modification degree) of the ethylenically unsaturated carboxylic acid or its anhydride on the olefin polymer is preferably 0.0001% by mass to 15% by mass, for example, 0.001% by mass to 10% by mass, relative to the olefin polymer. The addition reaction and graft reaction of the ethylenically unsaturated carboxylic acid or its anhydride on the olefin polymer can be carried out, for example, by a radical polymerization method in the presence of a solvent (such as xylene) and a catalyst (such as peroxide). The MFR of the carboxylic acid-modified polyolefin thus obtained under a load of 2160 g at 210 °C measured according to JIS K7210:2014 is preferably 0.2 g / 10 min to 30 g / 10 min, more preferably 0.5 g / 10 min to 10 g / 10 min. These adhesive resins can be used alone, or two or more of them can be used in combination.

[0095] The lamination order of the layer structure of the present invention is not particularly limited. In the case where the gas barrier layer is denoted as E, the adhesive layer is denoted as Ad, and the thermoplastic resin layer is denoted as T, for example, T / E / T, E / Ad / T, T / Ad / E / Ad / T, etc. can be mentioned. Each layer constituting the layer structure can be either a single layer or a multilayer. From the viewpoint of improving impact resistance, the layer structure preferably has a thermoplastic resin layer on the outermost layer.

[0096] When the layer structure of the present invention is a multi-layer structure, it can be manufactured by known methods such as co-extrusion molding, co-injection molding, extrusion lamination, dry lamination, etc. As the co-extrusion molding method, for example, co-extrusion lamination method, co-extrusion sheet molding method, co-extrusion blow molding method, and co-extrusion blow molding method can be cited. As examples of the layer structure obtained by this method, sheets, films, preforms, etc. can be cited.

[0097] (Use)

[0098] The layer structure of the present invention is excellent in both gas barrier properties and the stability of peel strength after secondary processing. For example, by reheating a sheet, film, preform, etc. of the layer structure of the present invention at a temperature below the melting point of the resin contained in the multi-layer structure, and performing uniaxial or biaxial stretching by thermoforming methods such as deep drawing, roll stretching, pantograph stretching, blow stretching, blow molding, etc., a desired stretched multi-layer structure can be obtained.

[0099] The layer structure of the present invention can also be used as, for example, a packaging material or container for packaging or storing a specified content. As examples of the content, food (such as fresh food, processed food, refrigerated food, frozen food, freeze-dried food, side dishes, semi-cooked food, etc.); beverages (such as drinking water, tea beverages, milk beverages, processed milk, soy milk, coffee, cocoa, soft drinks, soups, alcoholic beverages (such as beer, wine, shochu, sake, whiskey, brandy, etc.); pet food (such as dog food, cat food); feed or bait for livestock, poultry, and farmed fish; oils and fats (such as edible oils, industrial oils, etc.); pharmaceuticals (such as over-the-counter drugs, prescription drugs, general drugs, animal drugs); other chemical reagents, etc.

[0100] Examples

[0101] Hereinafter, examples will be cited to explain the present invention in detail, but the present invention is not limited to these examples.

[0102] (Evaluation method)

[0103] (1) Ethylene unit content and saponification degree

[0104] Dissolve the EVOH pellets obtained in each production example in DMSO-d6 and measure 1 1H-NMR (JNM-GX-500 type manufactured by JEOL Ltd.), and measure the ethylene unit content and saponification degree.

[0105] (2) Melt flow rate (MFR)

[0106] For the EVOH pellets obtained in each production example, the MFR was measured according to the method described in JIS K 7210:2014. Specifically, the EVOH pellets were filled into a barrel with an inner diameter of 9.55 mm and a length of 162 mm of a melt index measuring instrument L244 (manufactured by Takara Kogyo Co., Ltd.). After melting at 210°C, a plunger with a mass of 2,160 g and a diameter of 9.48 mm was evenly loaded on the molten resin composition. The amount of the resin composition extruded per unit time (g / 10 minutes) through an orifice with a diameter of 2.1 mm provided at the center of the barrel was measured.

[0107] (3) Quantification of sodium ions, phosphoric acid, and boric acid

[0108] 0.5 g of the EVOH pellets obtained in each production example was put into a Teflon (registered trademark) pressure vessel, 5 mL of concentrated nitric acid was added thereto, and it was decomposed at room temperature for 30 minutes. After 30 minutes, the pressure vessel was covered, and using a wet decomposition device ("MWS-2" manufactured by Actac Co., Ltd.), it was heated at 150°C for 10 minutes, then heated at 180°C for 5 minutes to decompose it, and then cooled to room temperature. The treatment solution was transferred to a 50 mL volumetric flask (made of TPX (registered trademark)), and the volume was made up with pure water. For this solution, elemental analysis was performed using an ICP emission spectroscopic analyzer (OPTIMA4300DV manufactured by PerkinElmer Co., Ltd.), and the amounts of sodium ions (sodium element), the amount of phosphoric acid in terms of phosphate radical conversion, and the content of boric acid were calculated respectively. It should be noted that when quantifying, standard curves prepared using commercially available standard solutions were used respectively.

[0109] (4) Acetic acid content

[0110] 20 g of the EVOH pellets obtained in each production example was put into 100 ml of ion-exchanged water, and heated and extracted at 95°C for 6 hours. Using phenolphthalein as an indicator, the extract was neutralized and titrated with 1 / 50 normal NaOH, and the acetic acid content was calculated. It should be noted that when calculating the acetic acid content, the content of phosphoric acid was taken into account.

[0111] (5) Gas barrier property (OTR)

[0112] The resin pellet groups obtained in the examples and comparative examples were formed into a film under the following conditions to obtain a single-layer film with a thickness of 20 μm. For the obtained single-layer film, after conditioning at 20°C / 65% RH, the oxygen permeability was measured using an oxygen permeability measuring device ("OX-Tran2 / 20" manufactured by ModernControls Co., Ltd.) under the conditions of 20°C / 65% RH. It should be noted that this measurement was carried out in accordance with ISO14663-2 annex C.

[0113] (Film-forming conditions)

[0114] · Equipment: 20mmΦ single-screw extruder (manufactured by D2020, Toyo Seiki Seisakusho Co., Ltd.)

[0115] · L / D: 20

[0116] · Screw: full thread

[0117] · Die width: 30 cm

[0118] · Winding roll temperature: 80 °C

[0119] · Screw rotation speed: 40 rpm

[0120] · Winding roll speed: 3.0 - 3.5 m / min

[0121] · Set temperature: C1 / C2 / C3 / D = 180 / 200 / 220 / 220 (°C)

[0122] (6) Heat formability (secondary processability)

[0123] Using the resin pellet groups (EVOH) obtained in the examples and comparative examples as the gas barrier layer, using polypropylene "Novatec (trademark) PP EA7AD" (PP) manufactured by Nippon Polypropylene Co., Ltd. as the thermoplastic resin layer, and using the adhesive polyolefin "Admer (trademark) QF500" (Ad1) manufactured by Mitsui Chemicals, Inc. as the adhesive layer, three types of 5-layer multi-layer structures (PP / Ad / EVOH / Ad / PP = 368 μm / 16 μm / 32 μm / 16 μm / 368 μm) were obtained under the following conditions. It should be noted that as the film-forming equipment, a winding roll with controllable temperature is provided after the extruder with a film-forming die, and the obtained multi-layer structure is wound using a winder.

[0124] (Film-forming conditions)

[0125] Extruder for EVOH: single-screw extruder (Labo Machine ME Type CO-EXT, manufactured by Toyo Seiki Co., Ltd.)

[0126] · Caliber 20mmΦ, L / D = 20, screw full thread type

[0127] · Feeding section / Compression section / Metering section / Die = 175 °C / 210 °C / 220 °C / 230 °C

[0128] Extruder for PP: single-screw extruder (GT-32-A, manufactured by Plastic Engineering Research Institute Co., Ltd.)

[0129] · Caliber 32mmΦ, L / D = 28, screw full thread type

[0130] · Feeding section / Compression section / Metering section / Die = 170 / 200 / 210 / 230 (°C)

[0131] Extruder for Ad1: Single-screw extruder (SZW20GT-20MG-STD, manufactured by Technovel Corporation)

[0132] · Diameter 20 mm Φ, L / D = 20, fully threaded screw

[0133] · Feeding section / Compression section / Measurement section / Die = 150 / 200 / 220 / 220 (°C)

[0134] Die: 300 mm wide hanger die (manufactured by Plastic Engineering Laboratory Co., Ltd.)

[0135] Temperature of the winding roll: 80 °C

[0136] The obtained multilayer structure is thermoformed into a cup shape (mold shape 70 Φ × 70 mm, draw ratio S = 1.0) at a sheet temperature of 150 °C using a thermoforming machine (manufactured by Asano Manufacturing Co., Ltd.) (using compressed air: 5 kg / cm 2 ), plug: 45 Φ × 65 mm, syntax form, mold temperature: 40 °C), to produce a thermoformed container. The bottom of the produced container is evaluated visually according to the following criteria. It should be noted that since the reference D has a poor appearance and is difficult to apply to packaging purposes, if it is A to C, it is judged that the secondary processability is good.

[0137] (Reference)

[0138] A: Uniform and no unevenness is observed

[0139] B: A little streaky unevenness is observed

[0140] C: Some streaky unevenness is observed

[0141] D: Obvious unevenness is observed

[0142] (7) Peel strength

[0143] After cutting out a 1.5 cm wide strip along the circumferential direction for one week from a 2 cm part at the bottom of the main body of the thermoformed container obtained by the above evaluation method (6), in an atmosphere of 23 °C and 50% RH, using the Autograph "AGS-H type" manufactured by Shimadzu Corporation, the T-peel strength is measured at a tensile speed of 250 mm / minute. During the measurement, the peel strength between the Ad layer and the EVOH layer on the inner side of the thermoformed container is measured. Ten samples are measured, and their average value and standard deviation are calculated. The smaller the standard deviation, the more stable the adhesiveness, and the higher the quality stability is judged.

[0144] (8) Spray stability

[0145] Using the resin pellet groups obtained in the use examples and comparative examples, an extrusion test was conducted under the following conditions to evaluate the ejection stability. The difference between the maximum barrel pressure and the front-end pressure after operating for 30 minutes at each rotational speed was measured, and the average value of the differences in pressure differences (3 points) at each rotational speed was evaluated using the following criteria. It should be noted that if it is A to C, it is judged that the ejection stability is good.

[0146] · Equipment: 40 mm Φ single-screw extruder (GT-40-A, manufactured by Plastic Engineering Research Institute Co., Ltd.)

[0147] · L / D: 26

[0148] · Compression ratio: 3.0

[0149] · Screw: full thread

[0150] · Screw rotational speed: 30, 60, 90 rpm

[0151] · Set temperature: C1 / C2 / C3 / AD / H1 / Die = 180 / 200 / 220 / 220 / 220 / 220 (°C)

[0152] (Criterion)

[0153] A: Less than 2 MPa

[0154] B: 2 MPa or more and less than 3 MPa

[0155] C: 3 MPa or more and less than 4 MPa

[0156] D: 4 MPa or more

[0157] (Production Example 1: Production of EVOH (A1-1) pellets)

[0158] Into a 200 L pressurized reaction vessel equipped with a jacket, a stirrer, a nitrogen inlet, an ethylene inlet, and an initiator addition port, 75.0 kg of vinyl acetate (hereinafter sometimes referred to as VAc) and 7.2 kg of methanol (hereinafter sometimes referred to as MeOH) were charged, and nitrogen was bubbled for 30 minutes to displace the nitrogen in the reaction vessel. Then, after adjusting the temperature inside the reaction vessel to 65 °C, ethylene was introduced so that the pressure in the reaction vessel (ethylene pressure) became 4.13 MPa, and 9.4 g of 2,2’-azobis(2,4-dimethylvaleronitrile) (“V-65” manufactured by Fujifilm Wako Pure Chemical Corporation) as an initiator was added to start the polymerization. During the polymerization, the ethylene pressure was maintained at 4.13 MPa and the polymerization temperature was maintained at 65 °C. After 4 hours, when the conversion rate of VAc (polymerization rate based on VAc) reached 49.7%, cooling was carried out, and at the same time, a substance obtained by dissolving 37.5 g of sorbic acid in 25 kg of methanol was added to the container to stop the polymerization. The reaction vessel was opened to remove ethylene, and then nitrogen was blown in to completely remove ethylene. Next, the polymerization solution was taken out of the container and diluted with 20 L of MeOH. This liquid was fed from the top of a tower-shaped container, and MeOH vapor was fed from the bottom of the tower to remove the unreacted monomers remaining in the polymerization solution together with the MeOH vapor, and a MeOH solution of ethylene-vinyl acetate copolymer (hereinafter sometimes referred to as EVAc) was obtained.

[0159] Next, 100 kg of a MeOH solution containing 20% by mass of EVAc was charged into a 300 L reaction vessel equipped with a jacket, a stirrer, a nitrogen inlet, a reflux condenser, and a solution addition port. While blowing nitrogen into this solution, the temperature was raised to 60 °C, and a MeOH solution with a sodium hydroxide concentration of 2 equivalents was added at a rate of 300 mL / min for 2 hours. After the addition of the MeOH solution of sodium hydroxide was completed, the temperature inside the system was maintained at 60 °C, and while allowing MeOH and methyl acetate generated in the saponification reaction to flow out of the reaction vessel, stirring was carried out for 2 hours to carry out the saponification reaction. Thereafter, 5.8 kg of acetic acid was added to stop the saponification reaction.

[0160] Thereafter, while heating and stirring at 80°C, 75 L of ion-exchanged water was added, and MeOH was allowed to flow out of the reaction tank to precipitate EVOH. The precipitated EVOH was collected by decantation and pulverized with a pulverizer. The obtained EVOH powder was put into a 1 g / L acetic acid aqueous solution (liquor ratio: 20; the aqueous solution was in a proportion of 20 L relative to 1 kg of the powder), stirred and washed for 2 hours. It was dewatered, further put into a 1 g / L acetic acid aqueous solution (liquor ratio: 20), stirred and washed for 2 hours. It was dewatered, put into ion-exchanged water (liquor ratio: 20), stirred and washed for 2 hours, and then dewatered. The above operations were repeated 3 times for purification. Then, it was immersed in 250 L of an aqueous solution containing 0.5 g / L of acetic acid and 0.1 g / L of sodium acetate with stirring for 4 hours, and then dewatered and dried at 60°C for 16 hours to obtain 10.1 kg of a crude dried product of EVOH. The above operations were carried out again to obtain 10.2 kg of a crude dried product of EVOH, and thus a total of 20.3 kg of a crude dried product of EVOH (A1-1) was obtained.

[0161] 20 kg of the above-obtained crude dried product of EVOH (A1-1), 8 kg of water, and 22 kg of MeOH were put into a 60 L stirring tank equipped with a jacket, a stirrer, and a reflux condenser, and stirred at 60°C for 5 hours to completely dissolve them, obtaining a resin composition solution. The solution was extruded through a metal plate with a diameter of 4 mm into a mixed solution of water / MeOH = 90 / 10 (volume ratio) cooled to -5°C, precipitated in a strand shape, and the strand was cut into pellet shape with a strand cutter to obtain water-containing pellets of EVOH. As a result of measuring the water content rate of the obtained water-containing pellets of EVOH with a halogen moisture meter "HR73" manufactured by Metra Co., Ltd., it was 52% by mass. The obtained water-containing pellets of EVOH were put into a 1 g / L acetic acid aqueous solution (liquor ratio: 20), stirred and washed for 2 hours. It was dewatered, further put into a 1 g / L acetic acid aqueous solution (liquor ratio: 20), stirred and washed for 2 hours. After dewatering, the acetic acid aqueous solution was renewed and the same operation was carried out. The substance obtained after washing with the acetic acid aqueous solution and then dewatering was put into ion-exchanged water (liquor ratio: 20), stirred and washed for 2 hours, and then dewatered. The above operations were repeated 3 times to obtain water-containing pellets of EVOH from which the catalyst residue during saponification reaction was removed.

[0162] The water-containing pellets are put into an aqueous solution (bath ratio: 20) with a sodium acetate concentration of 0.510 g / L, an acetic acid concentration of 0.8 g / L, and a phosphoric acid concentration of 0.04 g / L, and are impregnated for 4 hours with regular stirring to conduct chemical treatment. The pellets are dewatered, and dried at 80°C for 3 hours and at 105°C for 16 hours under a nitrogen gas stream with an oxygen concentration of 1% by volume or less, thereby obtaining cylindrical EVOH (A1-1) pellets (water content: 0.3% by mass) with an average diameter of 2.8 mm and an average length of 3.2 mm, containing acetic acid, sodium ions (sodium salts), and phosphoric acid.

[0163] (Production Examples 2 to 8, 11: Production of EVOH (A1-2) pellets to EVOH (A1-5) pellets, and EVOH (A2-1) pellets to EVOH (A2-4) pellets)

[0164] The polymerization conditions and saponification conditions of EVOH are set as shown in Table 1. In Production Examples 2, 4, 5, and 11, the aqueous solution used in the chemical treatment is an aqueous solution (bath ratio 20) with a sodium acetate concentration of 0.510 g / L, an acetic acid concentration of 0.8 g / L, a phosphoric acid concentration of 0.04 g / L, and a boric acid concentration of 0.57 g / L. Except for this, the operation is the same as in Production Example 1 to produce EVOH (A1-2) pellets to EVOH (A1-5) pellets, and EVOH (A2-1) pellets to EVOH (A2-4) pellets, respectively.

[0165] (Production Example 9: Production of EVOH (A1-1’) pellets)

[0166] An EVOH water-containing pellet is obtained by operating in the same manner as in Production Example 1. The water-containing pellet is put into ion-exchanged water (bath ratio 20) and stirred and washed for 2 hours, and the operation of dewatering is repeated 3 times. 10 kg of the dewatered pellets are used to remove the surface water by a centrifugal separator. The water-containing pellets with a water content of 33% by mass after centrifugal dehydration are put into Figure 1 the twin-screw extruder shown, the resin temperature at the nozzle is set to 100°C, and a treatment liquid containing an acetic acid / sodium acetate / phosphoric acid aqueous solution is added through the trace component addition part at the front end of the nozzle side, and melt-kneaded under the following conditions. The input amount of EVOH per unit time is 10 kg / hour (including the weight of the contained water), the input amount of the treatment liquid per unit time is 0.67 L / hour, and the composition of the treatment liquid is an aqueous solution containing 6.7 g / L of acetic acid, 11.3 g / L of sodium acetate, and 1 g / L of phosphoric acid. It should be noted that Figure 1 the twin-screw extruder shown is composed of a raw material supply part 29, a dewatering part 30, and a trace component addition part 31. The dewatering part 30 has a wedge-shaped net type dehydration slit 33. In addition, the screw is as Figure 1The screw is shown as a combination of a full-flight screw 34 and a reverse-flight screw 35. Furthermore, a temperature sensor 32 is provided at the end of the barrel.

[0167] (Twin-screw extruder conditions)

[0168] Device: 30mmΦ twin-shaft extruder

[0169] L / D: 45.5

[0170] Screw: Fully meshing in the same direction

[0171] Screw speed: 300rpm

[0172] Cylinder temperature: 100℃

[0173] Die temperature: 105℃

[0174] Number of mold holes: 5 holes (3mmΦ)

[0175] ·Coiling speed: 5m / min

[0176] Then, the molten EVOH resin ejected from the twin-screw extruder was Figure 2 The hot cutter 50 shown cuts the pellets into approximately spherical shapes. Figure 2 In the heat cutter 50 shown, EVOH resin in a molten state is supplied from the EVOH supply port 40 to the die 42 in the cutting box 45, and is cut by the rotating knife 43 rotating through the rotating shaft 44 to obtain EVOH water-containing pellets. On the other hand, in the cutting box 45, a water film 48 is formed by cooling water supplied from the cooling water supply port 46, and the EVOH water-containing pellets cut by the rotating knife 43 are cooled by the water film 48 and discharged from the pellet discharge port 49 together with the cooling water. The moisture content of the approximately spherical pellets is 20% by mass. The obtained pellets are dried at 90°C for 15 hours and at 105°C for 15 hours under a nitrogen flow, thereby obtaining approximately spherical EVOH (A1-1') pellets (moisture content 0.3% by mass) with a short diameter of 2.7 mm and a long diameter of 3.7 mm.

[0177] (Production Example 10: Preparation of EVOH (A2-1') Pellets)

[0178] The same operation as in Manufacturing Example 5 was performed to obtain a water-containing pellet of EVOH. Using the water-containing pellet, the same operation as in Manufacturing Example 9 was performed except that the treatment liquid added by the twin-screw extruder was changed to the following composition to obtain EVOH (A2-1') pellets (approximately spherical, short diameter 2.7 mm, long diameter 3.7 mm). The composition of the treatment liquid was set to an aqueous solution containing 6.7 g / L of acetic acid, 11.3 g / L of sodium acetate, 1 g / L of phosphoric acid, and 9 g / L of boric acid.

[0179] For the EVOH (A1-1) pellets to EVOH (A1-4) pellets, EVOH (A2-1) pellets to EVOH (A2-4) pellets, EVOH (A1-1') pellets, and EVOH (A2-1') pellets obtained in Production Examples 1 to 10, the ethylene unit content, saponification degree, MFR, sodium ion amount, phosphoric acid amount, boric acid amount, and acetic acid amount were measured according to the methods described in the above Evaluation Methods (1) to (4). The results are shown in Table 2. In any EVOH pellets, the sodium ion content was 100 ppm, the phosphate conversion amount of phosphoric acid was 40 ppm, and the acetic acid content was 200 ppm.

[0180]

[0181] [Table 2]

[0182]

[0183] (Example 1: Production and Evaluation of Resin Pellet Group)

[0184] 85 parts by mass of the EVOH (A1-1) pellets obtained in Production Example 1 and 15 parts by mass of the EVOH (A2-1) pellets obtained in Production Example 5 were dry-blended to produce a resin pellet group. For the obtained resin pellet group, OTR, secondary processability, peel strength, and ejection stability were evaluated according to the methods described in the above Evaluation Methods (5) to (8). The results are shown in Table 3.

[0185] (Examples 2 to 11 and Comparative Examples 1 to 2: Production and Evaluation of Resin Pellet Group)

[0186] Using the combinations of EVOH pellets shown in Table 3, except for this, each resin pellet group was produced and evaluated in the same manner as in Example 1. The results are shown in Table 3 or Table 4.

[0187] (Comparative Example 3: Production and Evaluation of EVOH Melt-Kneaded Pellets)

[0188] 85 parts by mass of the EVOH (A1-1) pellets obtained in Production Example 1 and 15 parts by mass of the EVOH (A2-1) pellets obtained in Production Example 5 were dry-blended and melt-kneaded under the extrusion conditions shown below to produce melt-kneaded pellets. Instead of the resin pellet group in Example 1, this melt-kneaded pellet was used, and except for this, the same operations as in Example 1 were performed for evaluation. The results are shown in Table 4.

[0189] (Extrusion Conditions)

[0190] Extruder: Twin-screw extruder "Laboplastmill" manufactured by Toyo Seiki Seisaku-sho, Ltd.

[0191] Screw diameter: 25 mm Φ

[0192] Screw rotation speed: 100 rpm

[0193] Feeder rotation speed: 80 rpm

[0194] Barrel and die temperature settings: C1 / C2 / C3 / C4 / C5 / Die = 180 / 210 / 220 / 220 / 220 / 220 (°C)

[0195] (Comparative Example 4: Evaluation of EVOH pellets)

[0196] Instead of the resin pellet group of Example 1, the EVOH (A1-1) pellets obtained in Production Example 1 were used as the resin pellet group, and otherwise, the operation was carried out and the evaluation was performed in the same manner as in Example 1. The results are shown in Table 4.

[0197] 60 parts by mass of the EVOH (A1-1) pellets obtained in Production Example 1, 10 parts by mass of the EVOH (A1-5) pellets obtained in Production Example 11, and 30 parts by mass of the EVOH (A2-2) pellets obtained in Production Example 6 were dry-blended to prepare a resin pellet group. For the obtained resin pellet group, OTR, secondary processability, peel strength, and ejection stability were evaluated according to the methods described in the above evaluation methods (5) to (8). The results were OTR: 0.5 cm 3 ·20 μm / m 2 ·day·atm, peel strength: 273.9 g / 15 mm, standard deviation of peel strength: 38.2. Appearance of the bottom of the obtained thermoformed container: A, ejection stability: A.

[0198] (Example 13: Preparation and evaluation of resin pellet group)

[0199] 40 parts by mass of the EVOH (A1-1) pellets obtained in Production Example 1, 30 parts by mass of the EVOH (A1-5) pellets obtained in Production Example 11, and 30 parts by mass of the EVOH (A2-2) pellets obtained in Production Example 6 were dry-blended to prepare a resin pellet group. For the obtained resin pellet group, OTR, secondary processability, peel strength, and ejection stability were evaluated according to the methods described in the above evaluation methods (5) to (8). The results were OTR: 0.6 cm 3 ·20 μm / m 2 ·day·atm, peel strength: 271.1 g / 15 mm, standard deviation of peel strength: 39.5. Appearance of the bottom of the obtained thermoformed container: A, ejection stability: A.

[0200]

[0201]

[0202] As is clearly shown in Tables 3 and 4, the single-layer films obtained by directly melt-molding the resin pellet groups of Examples 1 to 11, as is clear from the results of OTR and the like, all have excellent gas barrier properties. In addition, compared with the containers using the resin pellet groups of Comparative Examples 1 to 3 and the like, the thermoformed containers obtained using the resin pellet groups of Examples 1 to 11 are known to have significantly lower standard deviation values of peel strength, good adhesiveness between the Ad layer and the EVOH layer, and excellent quality stability. Furthermore, compared with the resin pellet groups of Comparative Examples 1 to 4 and the like, the resin pellet groups of Examples 1 to 11 are known to maintain good quality or sufficient durability in the secondary processability of thermoformed containers and the discharge stability of single-screw extruders.

[0203] Industrial Applicability

[0204] The resin pellet group of the present invention is useful for packaging various products in technical fields such as the food and beverage field, the pet food field, the oil industry field, the pharmaceutical field, and the like.

[0205] Explanation of Reference Numerals

[0206] 29 Raw material supply section

[0207] 30 Dewatering section

[0208] 31 Trace component addition section

[0209] 32 Temperature sensor

[0210] 33 Dewatering slit

[0211] 34 Full-thread screw

[0212] 35 Reverse-thread screw

[0213] 40 EVOH supply port

[0214] 42 Die

[0215] 43 Rotary knife

[0216] 45 Cutting box

[0217] 46 Cooling water supply port

[0218] 48 Water film

[0219] 49 Pellet discharge port

[0220] 50 Hot cutter

Claims

1. A resin pellet group, which is a resin pellet group for direct melt forming, wherein, it includes pellet (A1) containing ethylene-vinyl alcohol copolymer (a1) and pellet (A2) containing ethylene-vinyl alcohol copolymer (a2), the melt flow rate of the pellet (A1) measured at 210°C and 2160 g load in accordance with JIS K7210:2014 is 2 g / 10 min or more and less than 11 g / 10 min, and the melt flow rate of the pellet (A2) measured at 210°C and 2160 g load in accordance with JIS K7210:2014 is 11 g / 10 min or more and 40 g / 10 min or less, the difference (A2 - A1) between the melt flow rate of the pellet (A2) and the melt flow rate of the pellet (A1) is 1 g / 10 min or more and 20 g / 10 min or less, the difference between the melting point of the pellet (A1) and the melting point of the pellet (A2) is 8°C or more and 35°C or less, The ethylene unit content (EC a1 ) of the ethylene-vinyl alcohol copolymer (a1) is different from the ethylene unit content (EC a2 ) of the ethylene-vinyl alcohol copolymer (a2). The ethylene unit content (EC a1 ) of the ethylene-vinyl alcohol copolymer (a1) is 20 mol% or more and 50 mol% or less, and the ethylene unit content (EC a2 ) of the ethylene-vinyl alcohol copolymer (a2) is 30 mol% or more and 60 mol% or less. the mass ratio (A1 / A2) of the pellet (A1) to the pellet (A2) is 20 / 80 or more and 99 / 1 or less.

2. The resin pellet group according to claim 1, wherein, The absolute value of the difference between the ethylene unit content (EC a1 ) of the ethylene-vinyl alcohol copolymer (a1) and the ethylene unit content (EC a2 ) of the ethylene-vinyl alcohol copolymer (a2) is 4 mol% or more.

3. The resin pellet group according to claim 1 or 2, wherein, The ethylene unit content (EC a2 ) of the ethylene-vinyl alcohol copolymer (a2) is greater than the ethylene unit content (EC a1 ) of the ethylene-vinyl alcohol copolymer (a1).

4. A layer structure, which has a gas barrier layer, and the gas barrier layer is formed by directly melt forming the resin pellet group according to any one of claims 1 to 3.

5. The layer structure according to claim 4, wherein At least one surface of the gas barrier layer is provided with a thermoplastic resin layer.

6. The layer structure according to claim 5, which has a co-extrusion structure of the gas barrier layer and the thermoplastic resin layer.

7. A packaging material, which includes the layer structure according to any one of claims 4 to 6.

8. A container, which includes the layer structure according to any one of claims 4 to 6.

9. A method for manufacturing a layer structure, which includes: a step of directly melt forming a resin pellet group including pellet (A1) containing ethylene-vinyl alcohol copolymer (a1) and pellet (A2) containing ethylene-vinyl alcohol copolymer (a2) to form a gas barrier layer, the melt flow rate of the pellet (A1) measured at 210°C and 2160 g load in accordance with JIS K7210:2014 is 2 g / 10 min or more and less than 11 g / 10 min, the melt flow rate of the pellet (A2) measured at 210°C and 2160 g load in accordance with JIS K7210:2014 is 11 g / 10 min or more and 40 g / 10 min or less, the difference (A2 - A1) between the melt flow rate of the pellet (A2) and the melt flow rate of the pellet (A1) is 1 g / 10 min or more and 20 g / 10 min or less, the difference between the melting point of the pellet (A1) and the melting point of the pellet (A2) is 8°C or more and 35°C or less, The ethylene unit content (EC a1 ) of the ethylene-vinyl alcohol copolymer (a1) is different from the ethylene unit content (EC a2 ) of the ethylene-vinyl alcohol copolymer (a2). The ethylene unit content (EC a1 ) of the ethylene-vinyl alcohol copolymer (a1) is 20 mol% or more and 50 mol% or less, and the ethylene unit content (EC a2 ) of the ethylene-vinyl alcohol copolymer (a2) is 30 mol% or more and 60 mol% or less, and the mass ratio (A1 / A2) of the pellet (A1) to the pellet (A2) is 20 / 80 or more and 99 / 1 or less.

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