Resin composition and multilayer structure using the same

Abstract

A resin composition comprising polymer particles dispersed in a matrix of an ethylene-vinyl alcohol copolymer, wherein the polymer particles have an island structure, wherein one of the island and the sea component has a glass transition temperature above 30°C, and the other has a glass transition temperature below -10°C. This resin composition exhibits high gas barrier properties and excellent impact resistance, especially at low temperatures.

Description

Technical Field

[0001] This invention relates to resin compositions formed by dispersing polymer particles in a matrix of ethylene-vinyl alcohol copolymers. Furthermore, it relates to multilayer structures having layers comprising such resin compositions. Background Technology

[0002] Ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) exhibits excellent gas barrier properties against gases such as oxygen, and also possesses excellent melt moldability. Therefore, it is widely used as packaging material for food, pharmaceuticals, medical devices, and clothing. Furthermore, EVOH also exhibits excellent barrier properties against fuels such as gasoline, and is thus used in fuel cans and pipes. However, EVOH is a resin with relatively low flexibility, therefore, the impact resistance of the resulting molded products is sometimes insufficient.

[0003] One known method for improving the softness of resin is to add polymer particles having a core-shell structure to the resin, wherein the core-shell structure comprises a rubber layer (core) and a hard layer (shell) covering its outer periphery. Patent Document 1 describes a thermoplastic resin composition containing multilayer polymer particles and EVOH that exhibits excellent gas barrier properties and softness, and is useful for bottles and the like requiring impact resistance, wherein the multilayer polymer particles have an acrylic rubber, such as butyl acrylate as the inner layer (core), and polymethyl methacrylate, such as polymethyl methacrylate, as the outermost layer (shell).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent document 1: Japanese Patent Application Publication No. 9-249782. Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, molded articles obtained using the thermoplastic resin composition described in Patent Document 1 have room for improvement in impact resistance, especially at low temperatures. The present invention addresses these problems and aims to provide a resin composition with excellent gas barrier properties and impact resistance.

[0009] Methods for solving problems

[0010] The above problem is solved by providing a resin composition in which polymer particles are dispersed in an EVOH matrix, wherein the polymer particles have an island structure, and one of the sea component and the island component has a glass transition temperature (hereinafter sometimes abbreviated as Tg) of 30°C or higher, and the other has a Tg of -10°C or lower.

[0011] At this point, it is preferable that the Tg of the marine component is below -10°C and the Tg of the island component is above 30°C. In the transmission electron microscope image of the cross-section of the aforementioned polymer particles, the area ratio of the polymer component with a Tg of 30°C or higher to the polymer component with a Tg of -10°C or lower is preferably 5 / 95 to 70 / 30. It is also preferable to form a coating containing the same polymer component as the island component on the surface of the aforementioned polymer particles.

[0012] It is also preferable that the aforementioned polymer particles are aggregated to form secondary particles. In this case, the average primary particle size of the aforementioned polymer particles is more preferably 0.2 to 1 μm. Furthermore, the average secondary particle size of the aforementioned polymer particles is more preferably 1.1 to 10 μm.

[0013] The aforementioned polymer particles preferably comprise an acrylic polymer or a conjugated diene polymer. The mass ratio of the aforementioned polymer particles to the aforementioned EVOH is preferably 1 / 99 to 40 / 60. The ethylene content of the aforementioned EVOH is preferably 20 to 50 mol%.

[0014] A multilayer structure having layers comprising the aforementioned resin composition is a suitable embodiment of the present invention.

[0015] Invention Effects

[0016] The resin composition of the present invention has high gas barrier properties and excellent impact resistance, especially at low temperatures. Therefore, this resin composition is useful as a packaging material for food, pharmaceuticals, medical devices, clothing, etc., and is also useful as a fuel can or pipe that requires impact resistance at low temperatures. Attached Figure Description

[0017] Figure 1 This is a transmission electron microscope image of the cross-section of polymer particles in the resin composition granules of Example 1.

[0018] Figure 2 This is a transmission electron microscope image of the cross-section of polymer particles in the resin composition granules of Example 1. Detailed Implementation

[0019] The resin composition of the present invention is a resin composition formed by dispersing polymer particles in an EVOH matrix. The polymer particles have an island structure, wherein one of the sea component and the island component has a Tg of 30°C or higher, and the other has a Tg of -10°C or lower.

[0020] (EVOH)

[0021] The EVOH used in this invention is a copolymer having ethylene units and vinyl alcohol units. EVOH is typically obtained by saponifying an ethylene-vinyl ester copolymer. EVOH may contain ethylene ester units. The manufacture and saponification of ethylene-vinyl ester copolymers can be carried out by known methods. Examples of ethylene esters used in the manufacture of ethylene-vinyl ester copolymers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl decanoate, vinyl laurate, vinyl stearate, vinyl pivalate, and vinyl tert-carbonate, among which vinyl acetate is preferred.

[0022] The ethylene unit content of EVOH is preferably 20 mol% or more, more preferably 25 mol% or more. When the ethylene unit content is less than 20 mol%, there is a concern that the thermal stability of the resin composition may decrease, or that the impact resistance may decrease due to reduced flexibility. On the other hand, the ethylene unit content of EVOH is preferably 50 mol% or less, more preferably 35 mol% or less. If the ethylene unit content of EVOH exceeds 50 mol%, there is a concern that the gas barrier properties of the resin composition may decrease. The ethylene unit content and degree of saponification of EVOH can be determined by nuclear magnetic resonance (NMR).

[0023] The degree of saponification of EVOH is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 99 mol% or more. If the degree of saponification of EVOH is 90 mol% or more, the gas barrier properties, thermal stability, and moisture resistance are further improved. The degree of saponification of EVOH is usually 99.97 mol% or less, preferably 99.94 mol% or less.

[0024] Furthermore, the EVOH may contain units derived from monomers other than ethylene, ethylene esters, and their saponifications, without prejudice to the purpose of this invention. The content of units derived from other monomers in the EVOH is preferably 30 mol% or less, more preferably 20 mol% or less, further preferably 10 mol% or less, and particularly preferably 5 mol% or less, relative to all monomer units in the EVOH. When the EVOH contains units derived from other monomers, their content is preferably 0.05 mol% or more, more preferably 0.10 mol% or more, relative to all monomer units in the EVOH. Other monomers include, for example, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, or their anhydrides, salts, or monoalkyl or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefinic sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, and methyl allyl sulfonic acid, or their salts; vinyl silane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxy-ethoxy)silane, and γ-methacryloyloxypropylmethoxysilane; alkyl vinyl ethers, vinyl ketones, N-vinylpyrrolidone, vinyl chloride, and vinylidene chloride.

[0025] The suitable MFR (melt flow rate) for EVOH (measured at 210°C and 2160g load) is 0.1~100g / 10min. When the MFR of EVOH exceeds 100g / 10min, there is a concern about a decrease in the strength of the resulting molded article. A suitable MFR for EVOH is 50g / 10min or less, and even more suitable is 30g / 10min or less. On the other hand, when the MFR of EVOH is less than 0.1g / 10min, there is a concern about difficulty in melt molding. A suitable MFR for EVOH is 0.5g / 10min or more.

[0026] EVOH can be used alone or in combination with two or more types.

[0027] (polymer particles)

[0028] The polymer particles used in this invention have an island structure. Figure 1 and Figure 2 These are transmission electron microscope images of the cross-section of polymer particles in the resin composition granules of Example 1 described later. Figure 1 and Figure 2 As shown, the polymer particles (primary particles) of the present invention have an island structure, wherein the island structure has multiple island components (dark areas) and surrounding sea components (bright areas). In the present invention, the island structure refers to a core-shell structure having multiple island components, excluding a core surrounded by a shell. It should be noted that, preferably, multiple polymer particles (primary particles) aggregate in an EVOH matrix to form secondary particles.

[0029] Figure 1 and Figure 2 These are transmission electron microscope images of cross-sections of polymer particles stained with phosphomolybdic acid liquid. The island component (dark area) contains a polymer component with methyl methacrylate as the main component, having a Tg of 106°C, while the sea component (bright area) contains a polymer component with butyl acrylate as the main component, having a Tg of -39°C. Thus, in this invention, one of the sea component and the island component constituting the polymer particle must have a Tg of 30°C or higher, and the other must have a Tg of -10°C or lower. Figure 1 and Figure 2 In the polymer particles shown, the dark areas are polymer components with a Tg of 30°C or higher, and the bright areas are polymer components with a Tg of -10°C or lower. However, depending on the type of polymer components that make up the polymer particles, the dark and bright areas may sometimes be reversed.

[0030] In the polymer particles, the Tg of the sea component can be below -10°C and the Tg of the island component can be above 30°C, or the Tg of the sea component can be above 30°C and the Tg of the island component can be below -10°C. Importantly, in the polymer particles of the present invention, a sea-island structure is formed, in which a plurality of polymer components of another type (island components) are dispersed within one polymer component (sea component). Surprisingly, polymer particles with this sea-island structure can significantly improve the impact resistance of molded articles containing resin compositions containing EVOH compared to conventional polymer particles with a core-shell structure. From the viewpoint of further improving impact resistance, it is preferable that the Tg of the sea component is below -10°C and the Tg of the island component is above 30°C.

[0031] In a transmission electron microscope (TEM) image of the cross-section of polymer particles, the area ratio (high Tg component / low Tg component) of the polymer component with a Tg of 30°C or higher (high Tg component) to the polymer component with a Tg of -10°C or lower (low Tg component) is preferably 5 / 95 to 70 / 30. When the area ratio (high Tg component / low Tg component) is less than 5 / 95, the operability of recycling polymer particles may sometimes decrease. A more preferable area ratio (high Tg component / low Tg component) is 10 / 90 or higher. On the other hand, when the area ratio (high Tg component / low Tg component) exceeds 70 / 30, there is a concern that the impact resistance of the resin composition may be insufficient. A more preferable area ratio (high Tg component / low Tg component) is 60 / 40 or lower, and even more preferable is 50 / 50 or lower. The area ratio (high Tg component / low Tg component) is calculated by binarizing the TEM image of the cross-section of the polymer particles and determining the area ratio of the dark to the bright areas in the polymer particles. The binarized transmission electron microscope images were obtained using the methods described in the examples.

[0032] Figure 1 and Figure 2The diagram shows dark areas with the same composition as the islands formed on the outer periphery of the polymer particles. From the viewpoint of the operability of the polymer particles, it is preferable that the polymer particles of the present invention have an island structure and that a coating containing the same polymer composition as the islands is formed on the surface of the polymer particles. When such a coating is formed, the ratio of the coating thickness to the average primary particle size of the polymer particles (coating thickness / average primary particle size) in a transmission electron microscope image of the cross-section of the polymer particles is preferably 0.001 to 0.1. The ratio (coating thickness / average primary particle size) is more preferably 0.003 or more. On the other hand, the ratio (coating thickness / average primary particle size) is more preferably 0.045 or less. The average primary particle size of the polymer particles, the coating thickness, and the average secondary particle size of the polymer particles (described later) are calculated from a transmission electron microscope image of a cross-section of a polymer particle that is the same material used to calculate the area ratio (high Tg composition / low Tg composition). It should be noted that the particle size of polymer particles can be obtained by taking the arithmetic mean of the maximum length of the particles, and the average particle size can be calculated from the number of particles in the field of view and their particle sizes.

[0033] The area ratio of the total area of ​​island components present in the region where the distance from the centroid of the cross-section of the polymer particle (primary particle) is 75% or less relative to the distance from the centroid to the outline of the cross-section is preferably 0.1 or more. In this way, by including island components in the central portion of the polymer particle, the impact resistance of the resin composition is further improved. The area ratio is preferably 0.9 or less.

[0034] Examples of polymer components constituting the aforementioned polymer particles with a Tg below -10°C include acrylic polymers; olefin polymers such as ethylene-butene copolymers and ethylene-propylene copolymers; urethane polymers; styrene polymers such as styrene-ethylene / butene-styrene block copolymers (SEBS), styrene-isobutylene-styrene block copolymers (SIBS), styrene-ethylene / propylene-styrene block copolymers (SEPS), styrene-butadiene-styrene block copolymers (SBS), and styrene-isoprene-styrene block copolymers (SIS); conjugated diene polymers such as styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, acrylate-butadiene copolymers, and their hydrogenated derivatives; organosilicon polymers such as polysiloxanes; ethylene-based ionomer copolymers; polybutadiene, polyisoprene, butadiene-isoprene copolymers, and polychloroprene. These can be used individually or in combination. Among these, acrylic polymers or conjugated diene polymers are preferred as polymer components with a Tg below -10°C.

[0035] Acrylic polymers are manufactured by polymerizing acrylates. Examples of acrylates used in the synthesis of the aforementioned acrylic polymers include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and octyl acrylate. Among these, substances obtained by polymerizing butyl acrylate or ethyl acrylate are preferred.

[0036] When synthesizing acrylic polymers, other monofunctional polymeric monomers besides acrylates can be copolymerized as needed, within a Tg range of -10°C or below for the resulting polymer composition. Examples of other monofunctional polymeric monomers to be copolymerized include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, phenyl methacrylate, benzyl methacrylate, naphthyl methacrylate, isobornyl methacrylate, and other methacrylates; aromatic vinyl compounds such as styrene and α-methylstyrene; and acrylonitrile. The content of other monofunctional monomer units in the acrylic polymer relative to all monomer units is preferably 20% by mass or less.

[0037] When manufacturing conjugated diene polymers, other monofunctional polymerizable monomers besides conjugated dienes can be copolymerized as needed, within a Tg range of -10°C or below for the resulting polymer composition. Examples of other monofunctional polymerizable monomers to be copolymerized include those described above, which are used as other monofunctional polymerizable monomers for copolymerization with acrylates in the manufacture of acrylic polymers. The content of other monofunctional polymerizable monomer units in the conjugated diene polymer relative to all monomer units is preferably 20% by mass or less.

[0038] Polymer components with a Tg below -10°C preferably have cross-linked molecular chain structures to exhibit rubber elasticity. Furthermore, the molecular chains of the polymer component with a Tg below -10°C are preferably grafted onto the molecular chains of adjacent polymer components with a Tg above 30°C via chemical bonds. Therefore, in the polymerization of monomers used to form polymer components with a Tg below -10°C, it is sometimes preferable to use small amounts of multifunctional polymerizable monomers as cross-linking agents or grafting agents.

[0039] The multifunctional polymerizable monomers used in forming polymer components with a Tg below -10°C are monomers having two or more carbon-carbon double bonds within the molecule. These include esters formed by unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and cinnamic acid with unsaturated alcohols such as allyl alcohol and methallyl alcohol, or diols such as ethylene glycol and butanediol; and esters formed by dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and maleic acid with unsaturated alcohols. Specifically, examples include allyl acrylate, methallyl acrylate, allyl methacrylate, methallyl methacrylate, allyl cinnamate, methallyl cinnamate, diallyl maleate, diallyl phthalate, diallyl terephthalate, diallyl isophthalate, divinylbenzene, ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, and hexanediol di(meth)acrylate. Allyl methacrylate and ethylene glycol di(meth)acrylate may be used appropriately. It should be noted that the term "di(meth)acrylate" refers to the collective term for "diacrylate" and "dimethacrylate". They can be used alone or in combination.

[0040] In polymer components with a Tg below -10°C, the content of multifunctional polymeric monomer units relative to all monomer units is preferably 10% by mass or less. Excessive content of multifunctional polymeric monomer units may reduce the impact resistance of the resulting molded article. It should be noted that when using monomers with conjugated diene compounds as the main component, the monomer itself functions as a crosslinking point or grafting point; therefore, it is not necessarily necessary to use multifunctional polymeric monomers in combination.

[0041] Examples of free radical polymerizable monomers used in the synthesis of polymer components with a Tg of 30°C or higher constituting the polymer particles include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate; methacrylates with an alicyclic skeleton such as cyclohexyl methacrylate, isobornyl methacrylate, and adamantyl methacrylate; methacrylates with an aromatic ring such as phenyl methacrylate; aromatic vinyl ester compounds such as styrene and α-methylstyrene; and acrylonitrile. These monomers can be used alone or in combination. Preferred free radical polymerizable monomers include methyl methacrylate or styrene alone; or combinations of two or more free radical polymerizable monomers with these as the main component.

[0042] In the synthesis of polymer components with a Tg of 30°C or higher, it is sometimes preferable to use a small amount of multifunctional polymerizable monomers. Examples of multifunctional polymerizable monomers used in this process include those described above, which are substances used in forming polymer components with a Tg of -10°C or lower. The content of multifunctional polymerizable monomer units in the polymer components with a Tg of 30°C or higher relative to all monomer units in the polymer particles is preferably 10% by mass or less.

[0043] The polymer particles preferably have at least one functional group that is reactive or affinity for hydroxyl groups. This improves the dispersibility of the polymer particles in the EVOH matrix and further enhances gas barrier properties in the resulting resin composition. Such polymer particles can be obtained by using a polymerizable compound having a functional group that is reactive or affinity for hydroxyl groups as part of the monomer in the polymerization reaction used to manufacture them. Here, the functional group can be protected with a protecting group that does not impair the purpose of the invention and decouples when the EVOH is mixed with the polymer particles.

[0044] Examples of free radical polymerizable compounds having functional groups that are reactive or have an affinity for hydroxyl groups include unsaturated compounds that have functional groups that can react with the hydroxyl groups in EVOH when mixed with polymer particles to form intermolecular bonds such as chemical bonds or hydrogen bonds. Examples of functional groups that are reactive or have an affinity for hydroxyl groups include acid groups such as hydroxyl, epoxy, isocyanate (-NCO), and carboxyl groups; and anhydride groups such as maleic anhydride groups.

[0045] Examples of unsaturated compounds with the aforementioned functional groups include hydroxyl-containing polymers such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxyethyl crotonate, 3-hydroxy-1-propene, 4-hydroxy-1-butene, cis-4-hydroxy-2-butene, and trans-4-hydroxy-2-butene; epoxy-containing polymers such as glycidyl (meth)acrylate, allyl glycidyl ether, 3,4-epoxybutene, 4,5-epoxypentyl (meth)acrylate, 10,11-epoxyundecyl methacrylate, and p-glycidylstyrene; and carboxylic acids such as (meth)acrylate, crotonic acid, cinnamic acid, itaconic acid, maleic acid, citraconic acid, aconitic acid, medoconic acid, and methylene malonic acid. It should be noted that the term "di(meth)acrylate" refers to the general term for "diacrylate" and "dimethacrylate", while "(meth)acrylic acid" refers to the general term for "acrylic acid" and "methacrylic acid".

[0046] The amount of the free radical polymerizable compound having a functional group that is reactive or affinity for hydroxyl groups is preferably 0.01 to 75% by mass, more preferably 0.1 to 40% by mass, relative to all monomers used to manufacture polymer particles. It should be noted that examples of free radical polymerizable compounds having protected functional groups include tert-butyl methacryloylcarbamate.

[0047] The aforementioned functional groups can exist in any polymer component, provided they can substantially react with the hydroxyl groups in EVOH or form intermolecular bonds. A portion of the polymer particles in the resin composition can form chemical bonds between EVOH groups, and particularly preferably, functional groups exhibiting reactivity or affinity for hydroxyl groups are present in the molecular chains on the surface of the polymer particles.

[0048] The average primary particle size of the polymer particles in the resin composition is preferably 0.2 to 5 μm. When the average primary particle size of the polymer particles is less than 0.2 μm, when the polymer particles are dry-mixed with EVOH and the resin composition granules are obtained by melt extrusion, there is a tendency for the average secondary particle size of the polymer particles in the granules to become too large. Here, secondary particles refer to particles obtained by agglomeration of primary particles. The average primary particle size is more preferably 0.3 μm or more, and even more preferably 0.35 μm or more. On the other hand, when the average primary particle size exceeds 5 μm, the gas barrier properties may decrease due to the reduced number of primary particles constituting one secondary particle. The average primary particle size is more preferably 3 μm or less, even more preferably 2 μm or less, particularly preferably 1 μm or less, and most preferably 0.8 μm or less.

[0049] The average secondary particle size of the polymer particles in the resin composition is preferably 1 to 10 μm. By forming aggregates of smaller polymer particles in the resin composition, the impact resistance of the resulting molded article is further improved. The average secondary particle size is more preferably 1.1 μm or more, further preferably 1.5 μm or more, and particularly preferably 2.5 μm or more. On the other hand, the average secondary particle size is more preferably 8 μm or less, further preferably 6 μm or less, and particularly preferably 5 μm or less. Methods for adjusting the average secondary particle size of the polymer particles to a specified range include, for example, adjusting the screw speed during dry mixing, and increasing the amount of a second-stage grafting component added during the synthesis of the polymer particles.

[0050] The method for manufacturing polymer particles is not particularly limited; for example, it can be manufactured by the following methods. First, a polymer component (rubber latex) with a Tg of -10°C or lower is obtained by emulsion polymerization. Emulsion polymerization is carried out according to methods commonly used by those skilled in the art. Next, the obtained rubber latex is preferably aggregated. This further improves the impact resistance. Examples of agglomerating agents used in the aggregation of rubber latex include organic acids such as tartaric acid and their salts; inorganic acids such as hydrochloric acid and sulfuric acid and their salts.

[0051] As needed, after the polymer component (rubber latex) with a Tg below -10°C is aggregated, the aforementioned polymer component is grafted with free radical polymerizable monomers to form a polymer component with a Tg above 30°C. This grafting polymerization can be carried out in one stage or in multiple stages. The total polymerization time is preferably 5 to 100 hours. It can be considered that by carrying out polymerization for a longer time, the free radical polymerizable monomers permeate into the polymer component with a Tg below -10°C, thus easily forming an island structure. After grafting polymerization, polymer particles are separated from the copolymer latex according to methods commonly used by those skilled in the art (e.g., coagulation, drying, etc.).

[0052] In emulsion polymerization, common polymerization initiators can be used. Examples include inorganic peroxides such as potassium persulfate and sodium persulfate; organic peroxides such as benzoyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, and tert-butyl hydroperoxide (BHPO); and oil-soluble initiators such as azobisisobutyronitrile (AIO). These can be used alone or in combination of two or more. These initiators can be used as common redox polymerization initiators in combination with reducing agents such as sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, ferric sulfate, sodium ethylenediaminetetraacetate complexes, or sodium pyrophosphate.

[0053] There are no particular limitations on the emulsifiers used in emulsion polymerization; commonly used emulsifiers for emulsion polymerization can be used. Examples include sulfate-based surfactants such as sodium alkyl sulfate; sulfonate surfactants such as sodium alkylbenzene sulfonate, sodium alkyl sulfonate, sodium dioctyl sulfosuccinate, and sodium dioctyl sulfosuccinate; phosphate-based surfactants such as sodium alkyl phosphate and sodium polyoxyethylene alkyl ether phosphate; anionic surfactants such as sodium N-lauroyl sarcosinate and sodium N-acyl sarcosinate, and fatty acid-based surfactants such as potassium oleate. Furthermore, the aforementioned sodium salts can be potassium salts or other alkali metal salts and ammonium salts. These emulsifiers can be used alone or in combination of two or more. Furthermore, nonionic surfactants, such as polyoxyalkylene derivatives or their terminal hydroxyl-substituted or aryl-substituted derivatives, can also be used or in combination. From the viewpoint of polymerization stability and particle size control, sulfonate surfactants or phosphate surfactants are preferred, and more preferably, dioctyl sulfosuccinate, sodium dioctyl sulfosuccinate or polyoxyethylene alkyl ether phosphate salts are used.

[0054] (Resin composition)

[0055] The mass ratio of polymer particles to EVOH in the resin composition (polymer particles / EVOH) is preferably in the range of 1 / 99 to 40 / 60. If the mass ratio (polymer particles / EVOH) is 1 / 99 or higher, the impact resistance of the resin composition is further improved. More preferably, the mass ratio (polymer particles / EVOH) is 3 / 97 or higher, and even more preferably 5 / 95 or higher. If the mass ratio (polymer particles / EVOH) is 40 / 60 or lower, the gas barrier properties are further improved. More preferably, the mass ratio (polymer particles / EVOH) is 30 / 70 or lower, and even more preferably 25 / 75 or lower.

[0056] The total content of EVOH and polymer particles in the resin composition is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0057] If it does not impair the effects of the present invention, the resin composition may contain additives other than EVOH and polymer particles. Examples of such additives include resins, metal salts, acids, boron compounds, antioxidants, plasticizers, fillers, anti-blocking agents, lubricants, stabilizers, surfactants, colorants, ultraviolet absorbers, antistatic agents, desiccants, crosslinking agents, filler materials, and reinforcing materials such as various fibers, in addition to EVOH and the polymer components constituting the polymer particles. Among these, metal salts and acids are preferred from the viewpoint of the thermal stability of the resin composition and its adhesion to other resins.

[0058] From the viewpoint of further improving the interlayer adhesion of multilayer structures, alkali metal salts are preferred as metal salts, and from the viewpoint of thermal stability, alkaline earth metal salts are preferred. When the resin composition contains a metal salt, its content, calculated in terms of metal element content, is preferably 1 to 10,000 ppm. More preferably, the metal salt content, calculated in terms of metal element content, is 5 ppm or more, further preferably 10 ppm or more, and particularly preferably 20 ppm or more. On the other hand, more preferably, the metal salt content, calculated in terms of metal element content, is 5,000 ppm or less, further preferably 1,000 ppm or less, and particularly preferably 500 ppm or less. As a method for determining the metal salt content, for example, a method using an ICP-based luminescence analyzer to quantify a sample obtained by freeze-crushing dried EVOH granules can be cited.

[0059] From the viewpoint of improving thermal stability during melt molding, carboxylic acid compounds and phosphoric acid compounds are preferred as acids. When the resin composition contains a carboxylic acid compound, its content is preferably 1 to 10,000 ppm. The content of the carboxylic acid compound is more preferably 10 ppm or more, and even more preferably 50 ppm or more. On the other hand, the content of the carboxylic acid compound is more preferably 1,000 ppm or less, and even more preferably 500 ppm or less. As a method for determining the acid content, neutralization titration can be cited as an example.

[0060] When the resin composition contains a phosphoric acid compound, its content is preferably 1 to 10,000 ppm. More preferably, the content of the phosphoric acid compound is 10 ppm or more, and even more preferably 30 ppm or more. On the other hand, more preferably, the content of the phosphoric acid compound is 1,000 ppm or less, and even more preferably 300 ppm or less. As a method for determining the content of the phosphoric acid compound, for example, a method for quantifying a sample obtained by freeze-pulverizing dried EVOH granules using an ICP-based luminescence analyzer can be cited.

[0061] When the resin composition contains a boron compound, its content is preferably 1 to 2000 ppm. More preferably, the content of the boron compound is 10 ppm or more, and even more preferably 50 ppm or more. On the other hand, the content of the boron compound is more preferably 1000 ppm or less, and even more preferably 500 ppm or less. If the content of the boron compound in the resin composition is within the above range, the thermal stability during melt molding is further improved. The content of the boron compound can be determined using the same method as for the phosphate compound described above.

[0062] As a method for containing the aforementioned phosphoric acid compound, carboxylic acid compound, or boron compound in the resin composition, for example, it is suitable to add these compounds to the EVOH composition and mix them during the manufacture of the resin composition granules, etc. Examples of methods for adding these compounds to the EVOH composition include adding dried powder, adding a paste impregnated with a solvent, adding a suspension obtained by suspending in a liquid, adding a solution obtained by dissolving in a solvent, and impregnating the EVOH granules in a solution. From the viewpoint of uniformly dispersing the phosphoric acid compound, carboxylic acid compound, or boron compound, adding a solution obtained by dissolving in a solvent or impregnating the EVOH granules in a solution is preferred. As a solvent, from the viewpoints of additive solubility, cost, ease of handling, and safety of the working environment, water, for example, can be appropriately used.

[0063] The resin composition can be obtained by mixing EVOH, polymer particles, and other additives as needed. Known methods for mixing resins can be used as a method for mixing them. When using melt blending, EVOH, polymer particles, antioxidants, stabilizers, dyes, pigments, plasticizers, lubricants, fillers, other resins, etc., can be added, and melt blending can be performed using a screw extruder, for example, at 180-300°C.

[0064] The polymer particles supplied for manufacturing resin compositions can be, for example, a granular substance in which the surfaces of the polymer particles are fused together, provided that they can be sufficiently dispersed into granules when mixed with EVOH.

[0065] (Made product)

[0066] Molded articles comprising the aforementioned resin composition are suitable embodiments of the present invention. The resin composition of the present invention is melt-molded into various molded articles such as films, sheets, containers, tubes, and fibers. Known methods can be used for melt-molding of the resin composition, including extrusion molding, blow extrusion, blow molding, injection molding, melt spinning, etc. The melting temperature varies depending on the melting point of EVOH, but is preferably 150-270°C. At this time, the resin composition of the present invention can be temporarily granulated before molding, or EVOH, polymer particles, and other additives as needed can be dry-mixed and directly molded. These molded articles can also be pulverized and remolded for reuse. Furthermore, films, sheets, fibers, etc., can be subjected to uniaxial or biaxial stretching or thermoforming for secondary processing.

[0067] Both extrusion blow molding and injection blow molding can be used as blow molding methods. In extrusion blow molding, the extruded tube can be pre-cut, cooled, and then reheated for blow molding; however, the so-called direct blow molding method, which directly blow molds the extruded tubular molten preform, is more suitable. Furthermore, in injection blow molding, methods include pre-injecting a preform with a base and then blow molding it at a high temperature during cooling, or reheating it after cooling for blow molding.

[0068] The molded article of the present invention can be a single layer or multiple layers, preferably a multilayer structure having a layer comprising the aforementioned resin composition. The thickness of the multilayer structure is not particularly limited, and is typically 10 to 5000 μm. The ratio of the thickness of the resin composition layer to the thickness of the aforementioned multilayer structure (resin composition layer / multilayer structure) is preferably 0.02 to 0.2. When the thickness ratio (resin composition layer / multilayer structure) exceeds 0.2, there are concerns about deterioration in formability and increased cost. On the other hand, when the thickness ratio (resin composition layer / multilayer structure) is less than 0.02, there are concerns about reduced gas barrier properties.

[0069] The layer composition of the aforementioned multilayer structure is not particularly limited. If the thermoplastic resin layer other than EVOH is designated as A, the resin composition layer as B, and the adhesive resin layer as C, then layer compositions such as A / B, A / B / A, A / C / B, A / C / B / C / A, A / B / A / B / A, and A / C / B / C / A / C / B / C / A can be exemplified. Further addition of other layers is also permissible. When multiple other thermoplastic resin layers are provided, different layers or identical layers can be used. Furthermore, layers containing recycled resin derived from waste materials such as scraps and non-standard molded products generated during molding can be separately provided, or layers containing blends of recycled resin and other thermoplastic resins can be used as other thermoplastic resin layers.

[0070] The resin used as the adhesive resin layer is preferably a polyurethane-based, polyester-based single-component or two-component curable adhesive; or a polyolefin having carboxyl groups, carboxylic anhydride groups, or epoxy groups. From the viewpoint of excellent adhesion to EVOH and to polyolefins, a polyolefin having carboxyl groups, carboxylic anhydride groups, or epoxy groups is more preferred.

[0071] Examples of polyolefins containing carboxyl groups include polyolefins copolymerized with acrylic acid or methacrylic acid. As ionomers are representative, all or part of the carboxyl groups in the polyolefin can exist in the form of metal salts. Examples of polyolefins containing carboxylic anhydride groups include polyolefins grafted with maleic anhydride or itaconic acid. Furthermore, examples of epoxy-containing polyolefin resins include polyolefins copolymerized with glycidyl methacrylate. From the viewpoint of excellent adhesion, polyolefins modified with carboxylic anhydrides such as maleic anhydride are preferred, and polyethylene is particularly preferred.

[0072] Examples of thermoplastic resins used as other thermoplastic resin layers include polyethylene (linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene), ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene, propylene-α-olefin copolymer, polybutene, polypentene, and other polyolefins; polyesters such as polyethylene terephthalate; polyester elastomers; polyamides such as nylon 6 and nylon 66; polystyrene; polyvinyl chloride; polyvinylidene chloride; acrylic resins; vinyl ester resins; polyurethane elastomers; polycarbonate; chlorinated polyethylene; and chlorinated polypropylene. Among these, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene, and polyester are preferred.

[0073] As a method for manufacturing the aforementioned multilayer structure, known methods can be used, such as co-extrusion molding, co-injection molding, and extrusion coating.

[0074] As a method for manufacturing blow-molded containers comprising multi-layer structures, co-extrusion blow molding and co-injection blow molding can be appropriately employed. As a method of co-extrusion blow molding, a suitable method is the so-called direct blow molding method: using a multi-layer extruder with at least two extruders, a resin composition, other thermoplastic resins, and adhesive resins as needed are supplied to their respective extruders, and are respectively mixed and melt-extruded, so that the layers are extruded in such a way that they merge and flow closely inside the mold for forming the multi-layer preform or on the outside immediately after being ejected from the mold, to obtain a tubular multi-layer preform. Then, the preform is blow-molded in the molten state to obtain a multi-layer container.

[0075] Molded articles obtained using the resin composition of the present invention exhibit high gas barrier properties and excellent impact resistance, especially at low temperatures. Therefore, these molded articles are useful as packaging materials for food, pharmaceuticals, medical devices, clothing, etc., and are also useful as fuel containers and tubing requiring impact resistance at low temperatures. Example

[0076] The present invention will be described in more detail below using examples.

[0077] [Structural observation of polymer particles]

[0078] Pretreatment and staining

[0079] Ultrathin sections for transmission electron microscopy were prepared by cutting the resin composition granules obtained in the various examples and comparative examples using a Reika Microtome (model: Ultracut S / FC-S). It should be noted that the cutting conditions are as follows.

[0080] Sample: -100℃

[0081] Cutting blade: -100℃

[0082] Cutting speed: 0.4~1.0 mm / s

[0083] Cutting thickness setting: 85nm

[0084] Thickness: 85nm.

[0085] The resulting ultrathin sections were recovered onto a copper mesh (1000 mesh) and stained electronically using phosphomolybdic acid solution.

[0086] Structural observation

[0087] Morphological observation was performed under the following conditions. For structural observation of polymer particles, a transmission electron microscope (model: HT7700, corresponding to 3DTEM) manufactured by Hitachi High Tech Noroze Co., Ltd., equipped with a LaB6 electron gun was used.

[0088] Accelerating voltage: 100KV

[0089] LaB6 electron beam exposure: 10 μA

[0090] Electron beam spot size: 1μm

[0091] Condenser aperture: 0.1mm (No.2)

[0092] 3D objective lens movable aperture: 0.16mm (No.3)

[0093] CCD camera for photographic recording: AMT company's bottom-mounted camera (model: XR81B, 8-megapixel camera).

[0094] Binarization

[0095] The calculation of bright area, dark area, average primary particle size, average secondary particle size, and coating thickness is performed by image analysis of an image whose entire field of view is occupied by the cross-section of the resin composition granules. The image analysis software used is Image-Pro Plus, manufactured by Rober Co., Ltd., Japan. In the image analysis, firstly, the average primary particle size, average secondary particle size, and bright and dark areas of the polymer particles are calculated by tracing the contours of the granular portions in the image. Particle contour tracing is performed for the contrast-adjusted image. This contrast adjustment is performed automatically using the "Best Contrast Match" command of the image analysis software. Furthermore, the granular portions are separated / extracted from the background (LSCF area) using the binarization "Segmentation (Color Extraction)" command. Specifically, binarization is performed by converting the contrast-adjusted image into a black-and-white image where the white portions are used as bright areas.

[0096] Furthermore, the total white portion of the polymer particles (primary particles) in the binarized image is taken as the bright area, and the total black portion is taken as the dark area. Using the aforementioned binarized image, the region where the distance from the centroid of the cross-section of the polymer particle (primary particle) is less than 75% of the distance from the centroid to the outline of the cross-section is determined (this region is shown in...). Figure 2 The total area of ​​the dark regions (island components) within the image is calculated. Furthermore, using the aforementioned binarized image, the thickness of the coating (dark region) on the surface of the polymer particles (primary particles) is determined. It should be noted that the areas of the bright and dark regions are calculated as the arithmetic mean of the number of particles contained in the field of view.

[0097] The average primary and secondary particle sizes of the polymer particles are obtained as the arithmetic mean of the maximum lengths between the particle profiles. The average particle size is calculated from the number of particles in the field of view and their sizes.

[0098] Oxygen permeability (OTR)

[0099] Fabrication of single-layer membrane

[0100] Using a single-screw extruder (Toyo Seiki Co., Ltd., D2020, D (mm) = 20, L / D = 20, compression ratio = 3.0, screw: full spiral), the resin composition granules obtained in the Examples and Comparative Examples were used to form a film, thereby obtaining a single-layer film with a thickness of 20 μm. The extrusion conditions are shown below.

[0101] Extrusion temperature: 220℃

[0102] Mold width: 30cm

[0103] Traction roller temperature: 80℃

[0104] Screw speed: 45 rpm

[0105] Traction roller speed: 3.4 m / min.

[0106] After conditioning the obtained 20 μm thick monolayer membrane at 20 °C / 65% RH, the oxygen permeability (OTR) was measured using an oxygen permeability measuring device (ModernControl OX-Tran2 / 20) at 20 °C / 65% RH.

[0107] [Impact Resistance Evaluation]

[0108] Manufacturing of blow-molded containers

[0109] Using the obtained resin composition granules, high-density polyethylene resin [density 0.96 g / cc, MFR (measured at 210°C and 2160 g load) 0.5 g / 10 min], and adhesive resin (Mitsui Chemicals' "ADMER GT-6A"), a Suzuki Kogyo TB-ST-6P blow molding machine was used. After releasing a 5-layer preform (inner side) of high-density polyethylene / adhesive resin / resin composition / adhesive resin / high-density polyethylene (outer side) at 210°C for 2 hours, the operation was directly interrupted for 2 hours while still heated. Afterwards, the operation was restarted, and blow-molded containers were manufactured after a specified time. At this point, the container is cooled at an internal mold temperature of 15°C for 20 seconds to form a 500mL can (blow-molded container) with a total layer thickness of 940μm [(inner) high-density polyethylene / adhesive resin / resin composition / adhesive resin / high-density polyethylene (outer) = (inner) 400 / 50 / 40 / 50 / 400μm (outer)]. The can has a bottom diameter of 100mm and a height of 400mm.

[0110] drop test

[0111] Fill the resulting 500mL can with 400mL of ethylene glycol, heat-seal the opening with a multilayer film of 40μm polyethylene / 12μm aluminum foil / 12μm polyethylene terephthalate, and then cap it. After cooling the can at -40°C for 3 days, drop it from a height of 6m with the opening facing upwards to check for breakage. Similarly, the test was conducted on 10 cans, and the impact resistance was evaluated based on the number of broken cans.

[0112] Impact resistance evaluation criteria

[0113] A: Fewer than 2 cans were damaged.

[0114] B: Two or more but fewer than four tanks were damaged.

[0115] C: Four or more but fewer than six tanks were damaged.

[0116] D: More than 6 tanks were damaged.

[0117] [Manufacturing of EVOH-1]

[0118] Two kg of EVOH resin with an ethylene unit content of 32 mol% and a saponification degree of 99.8 mol% was added to 18 kg of a mixed solvent of water / methanol = 40 / 60 (mass ratio) and stirred at 60°C for 6 hours until completely dissolved. The solution was then continuously extruded from a 4 mm diameter nozzle into a coagulation bath at 0°C with a water / methanol ratio of 90 / 10 (mass ratio), causing the EVOH to solidify into a filament. This filament was then fed into a granulator to obtain porous EVOH flakes.

[0119] The obtained porous EVOH flakes were washed with an aqueous acetic acid solution and deionized water, and then impregnated with an aqueous solution containing acetic acid, potassium dihydrogen phosphate, sodium acetate, and orthoboric acid. After separating the treated aqueous solution from the EVOH flakes and removing the liquid, the flakes were placed in a hot air dryer and dried at 80°C for 4 hours, followed by drying at 100°C for 16 hours to obtain dried EVOH granules (EVOH-1). EVOH-1 has an acetic acid content of 150 ppm, a sodium ion content of 140 ppm, a phosphoric acid compound content (converted to phosphate) of 45 ppm, and a boron compound content (converted to boron) of 260 ppm. Furthermore, the MFR (ASTM-D1238, 210°C, 2160 g load) of EVOH-1 is 3.7 g / 10 minutes.

[0120] [Manufacturing of EVOH-2 and EVOH-3]

[0121] EVOH-2 and EVOH-3 are manufactured in the same manner as EVOH-1, except that they are produced using either EVOH-2 (27 mol% ethylene unit content, 99.9 mol% saponification degree) or EVOH-3 (44 mol% ethylene unit content, 99.9 mol% saponification degree). The contents of acetic acid, sodium ions, phosphoric acid compounds, and boron compounds in EVOH-2 and EVOH-3 are the same as in EVOH-1. Furthermore, the MFR (ASTM-D1238, 210°C, 2160 g load) for EVOH-2 and EVOH-3 are 4.0 g / 10 min and 3.3 g / 10 min, respectively.

[0122] [Manufacturing of Polymer Particles-1]

[0123] The following components were added to a pressure vessel equipped with a stirrer and polymerized at 45°C for 16 hours until polymerization was complete. The polymerization yield was approximately 100%.

[0124] Rubber ingredients

[0125] 70 parts by weight of n-butyl acrylate

[0126] 0.2 parts by weight of ethylene glycol dimethacrylate

[0127] 0.195 parts by weight of diisopropylbenzene peroxide

[0128] Ferric sulfate (FeSO4・7H2O) 0.002 parts by mass

[0129] Sodium ethylenediaminetetraacetate 0.003 parts by weight

[0130] Sodium formaldehyde sulfoxylate 0.049 parts by weight

[0131] Potassium oleate 0.9 parts by weight

[0132] Sodium pyrophosphate 0.1 parts by weight

[0133] 175 parts by weight of distilled water.

[0134] Relative to the total amount of the obtained rubber latex, 0.035 parts by weight of sodium dioctyl sulfosuccinate were added and fully stabilized, followed by the slow addition of 2% by weight tartaric acid aqueous solution and 2% by weight sodium hydroxide aqueous solution, thereby causing a primary particle aggregation under pH 7-9 conditions.

[0135] The first grafting component, as shown below, was added to the obtained rubber latex, and polymerization was continued at 45°C for 16 hours. The polymerization yield was approximately 100%.

[0136] First grafting component

[0137] 14 parts by weight of methyl methacrylate

[0138] 3 parts by weight of glycidyl methacrylate

[0139] 0.12 parts by weight of ethylene glycol dimethacrylate

[0140] 0.02 parts by weight of diisopropylbenzene peroxide

[0141] Sodium formaldehyde sulfoxylate 0.01 parts by weight

[0142] 0.03 parts by weight of sodium dioctyl sulfosuccinate.

[0143] The resulting latex was further treated with a second grafting component as shown below, and polymerization was continued at 45°C for 16 hours. The polymerization yield was approximately 100%.

[0144] Second grafting component

[0145] 13 parts by weight of methyl methacrylate

[0146] 0.1 parts by weight of ethylene glycol dimethacrylate

[0147] 0.015 parts by weight of diisopropylbenzene peroxide.

[0148] The obtained latex was salted out with an aqueous sodium chloride solution, and then subjected to post-treatment including filtration, washing, and drying to obtain polymer particles-1 containing multi-component grafted resin.

[0149] [Manufacturing of Polymer Particles-2]

[0150] Except for changing the amounts of each component as described below, polymer particles-2 are manufactured in the same manner as polymer particles-1.

[0151] Rubber ingredients

[0152] 90 parts by weight of n-butyl acrylate

[0153] First grafting component

[0154] 2 parts by weight of methyl methacrylate

[0155] Second grafting component

[0156] 5 parts by weight of methyl methacrylate.

[0157] [Manufacturing of Polymer Particles-3]

[0158] Except for changing the amounts of each component as described below, polymer particles-3 are manufactured in the same manner as polymer particles-1.

[0159] Rubber ingredients

[0160] 60 parts by weight of n-butyl acrylate

[0161] First grafting component

[0162] 19 parts by weight of methyl methacrylate

[0163] Second grafting component

[0164] 18 parts by weight of methyl methacrylate.

[0165] [Manufacturing of Polymer Particles-4]

[0166] Except for changing the amounts of each component as described below, polymer particles-4 are manufactured in the same manner as polymer particles-1.

[0167] Rubber ingredients

[0168] 40 parts by weight of n-butyl acrylate

[0169] First grafting component

[0170] 29 parts by weight of methyl methacrylate

[0171] Second grafting component

[0172] 28 parts by weight of methyl methacrylate.

[0173] [Manufacturing of Polymer Particles-5]

[0174] Except for changing the amounts of each component as described below, polymer particles-5 are manufactured in the same manner as polymer particles-1.

[0175] Rubber ingredients

[0176] 23 parts by weight of n-butyl acrylate

[0177] First grafting component

[0178] 5 parts by weight of methyl methacrylate

[0179] Second grafting component

[0180] 4 parts by weight of methyl methacrylate.

[0181] [Manufacturing of Polymer Particles-6]

[0182] Except for changing the amounts of each component as described below, polymer particles-6 are manufactured in the same manner as polymer particles-1.

[0183] Rubber ingredients

[0184] 140 parts by weight of n-butyl acrylate

[0185] Potassium oleate 0.01 parts by weight

[0186] First grafting component

[0187] 28 parts by weight of methyl methacrylate.

[0188] [Manufacturing of Polymer Particles-7]

[0189] Except for changing the amounts of each component as described below, polymer particles-7 are manufactured in the same manner as polymer particles-1.

[0190] First grafting component

[0191] 24 parts by weight of methyl methacrylate

[0192] Second grafting component

[0193] 3 parts by weight of methyl methacrylate.

[0194] [Manufacturing of Polymer Particles-8]

[0195] Except for changing the amounts of each component as described below, polymer particles-8 are manufactured in the same manner as polymer particles-1.

[0196] First grafting component

[0197] 3 parts by weight of methyl methacrylate

[0198] Second grafting component

[0199] 24 parts by weight of methyl methacrylate.

[0200] [Manufacturing of Polymer Particles-9]

[0201] Styrene is used instead of methyl methacrylate as the first and second grafting components. Otherwise, polymer particles-9 are manufactured in the same manner as polymer particles-1.

[0202] [Manufacturing of Polymer Particles-10]

[0203] Except for not polymerizing the first and second grafted components, polymer particles-10 are manufactured in the same manner as polymer particles-1.

[0204] Example 1

[0205] 90 parts by weight of EVOH-1 as EVOH and 10 parts by weight of polymer particles-1 as polymer particles were dry-mixed at a screw speed of 50 rpm. The mixture was then extruded at a temperature of 200°C using a 30 mm φ co-rotating twin-screw extruder ("TEX-30N" manufactured by Nippon Steel). The resulting mixture was then granulated to obtain resin composition granules.

[0206] The obtained resin composition granules were subjected to structural observation using the method described above. Transmission electron microscopy images (before binarization) of the cross-sections of the polymer particles in the observed resin composition granules are shown below. Figure 1 and Figure 2 .Depend on Figure 1 and Figure 2Polymer particle-1 was confirmed to have formed secondary particles by the aggregation of multiple primary particles within the EVOH-1 matrix. Each primary particle comprises: a sea component (bright area) containing a polymer component with n-butyl acrylate as the main component (Tg: -39°C), and multiple island components (dark area) containing a polymer component with methyl methacrylate as the main component (Tg: 106°C). The average primary particle size of polymer particle-1 is 0.4 μm, and the average secondary particle size is 3 μm. A coating (dark area) containing the same polymer component as the island components is formed on the surface of the primary particles, and the ratio of the coating thickness to the average primary particle size (coating thickness / average primary particle size) is 0.02. Furthermore, a region was identified where the distance from the centroid of the cross-section of the primary particle is less than 75% of the distance from the centroid to the outline of the cross-section (this region is shown in...). Figure 2 The total area of ​​the dark regions (island components) within the aforementioned region was calculated. Furthermore, the ratio of the total area of ​​the dark regions (island components) within the aforementioned region to the total area of ​​the dark regions (island components) within the cross-section of the primary particle was found to be 0.62. The oxygen permeability and impact resistance of the resulting resin composition granules were evaluated. The results are shown in Table 1.

[0207] Examples 2-9

[0208] Except for changing the type of polymer particles used to those shown in Table 1, the same procedure as in Example 1 was followed for the preparation and evaluation of the resin composition granules. The results are shown in Table 1.

[0209] Example 10

[0210] Except that the screw speed was set to 80 rpm when dry mixing EVOH with polymer particles, the same procedure as in Example 1 was followed to manufacture and evaluate the resin composition granules. The results are shown in Table 1.

[0211] Example 11

[0212] Except for the addition of 70 parts by weight of EVOH-1 and 30 parts by weight of polymer particles-1, the same procedure as in Example 1 was followed to manufacture and evaluate the resin composition granules. The results are shown in Table 1.

[0213] Examples 12 and 13

[0214] Except for changing the type of EVOH used to those shown in Table 1, the same procedure as in Example 1 was followed for the preparation and evaluation of the resin composition granules. The results are shown in Table 1.

[0215] Comparative Example 1

[0216] Except that core-shell particles (PARALOID EXL-2300G, manufactured by Dow) were used instead of polymer particles-1, the preparation and evaluation of the resin composition granules were carried out in the same manner as in Example 1. The core-shell particles used here have a structure in which a core is surrounded by a shell. The results are shown in Table 1.

[0217] Comparative Example 2

[0218] Except that polymer particles-10 were used instead of polymer particles-1, the same procedure as in Example 1 was followed for the preparation and evaluation of the resin composition granules. The results are shown in Table 1.

[0219] Comparative Example 3

[0220] Except that polyamide (PA) (BASF's "ULTRAMID C40LN") was used instead of EVOH-1, the preparation and evaluation of the resin composition granules were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0221]

[0222]

Claims

1. A resin composition comprising polymer particles dispersed in a matrix of an ethylene-vinyl alcohol copolymer. The polymer particles have an island structure, with one of the sea component and the island component having a glass transition temperature above 30°C, and the other having a glass transition temperature below -10°C. Polymers with a glass transition temperature below -10℃ are acrylic polymers or conjugated diene polymers. Polymers with a glass transition temperature above 30°C are polymers obtained by polymerizing methyl methacrylate or styrene. The molecular chains of polymer components with a glass transition temperature below -10℃ were grafted onto the molecular chains of adjacent polymer components with a glass transition temperature above 30℃ through chemical bonds. In the transmission electron microscope image of the cross-section of the polymer particles, the area ratio of the polymer component with a glass transition temperature above 30°C to the polymer component with a glass transition temperature below -10°C is 5 / 95 to 70 / 30. The average primary particle size of the polymer particles is 0.2~5μm. The mass ratio of the polymer particles to the ethylene-vinyl alcohol copolymer is 1 / 99 to 40 / 60. The ethylene content of the ethylene-vinyl alcohol copolymer is 20-50 moles.

2. The resin composition according to claim 1, wherein, The glass transition temperature of marine components is below -10℃, while that of island components is above 30℃.

3. The resin composition according to claim 1 or 2, wherein, In the transmission electron microscope image of the cross-section of the polymer particles, the area ratio of the polymer component with a glass transition temperature above 30°C to the polymer component with a glass transition temperature below -10°C is 10 / 90 to 60 / 40.

4. The resin composition according to claim 1 or 2, wherein, A coating containing the same polymer components as the island components is formed on the surface of the polymer particles.

5. The resin composition according to claim 1 or 2, wherein, The polymer particles aggregate to form secondary particles.

6. The resin composition according to claim 5, wherein, The average primary particle size of the polymer particles is 0.2~1μm.

7. The resin composition according to claim 5, wherein, The average secondary particle size of the polymer particles is 1.1~10μm.

8. The resin composition according to claim 1 or 2, wherein, The mass ratio of the polymer particles to the ethylene-vinyl alcohol copolymer is 3 / 97 to 30 / 70.

9. The resin composition according to claim 1 or 2, wherein, The ethylene-vinyl alcohol copolymer has an ethylene content of 25-35 mol.

10. A multilayer structure having a layer comprising the resin composition according to any one of claims 1 to 9.

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