阅读说明：本技术 树脂组合物和使用了其的多层结构体 (Resin composition and multilayer structure using same ) 是由 铃木真 于 2020-03-04 设计创作，主要内容包括：树脂组合物,其为在乙烯-乙烯醇共聚物的基质中分散聚合物颗粒而成的树脂组合物,前述聚合物颗粒具有海岛结构,海成分和岛成分中的一者的玻璃化转变温度为30℃以上,另一者的玻璃化转变温度为-10℃以下。该树脂组合物具有高的气体阻隔性,且耐冲击性、尤其是低温下的耐冲击性也优异。(A resin composition comprising an ethylene-vinyl alcohol copolymer matrix and polymer particles dispersed therein, wherein the polymer particles have a sea-island structure, and one of the sea component and the island component has a glass transition temperature of 30 ℃ or higher and the other has a glass transition temperature of-10 ℃ or lower. The resin composition has high gas barrier properties and is excellent in impact resistance, particularly impact resistance at low temperatures.)

1. A resin composition comprising an ethylene-vinyl alcohol copolymer matrix and polymer particles dispersed therein,

the polymer particles have a sea-island structure, and one of the sea component and the island component has a glass transition temperature of 30 ℃ or higher and the other has a glass transition temperature of-10 ℃ or lower.

2. The resin composition according to claim 1, wherein the glass transition temperature of the sea component is-10 ℃ or lower, and the glass transition temperature of the island component is 30 ℃ or higher.

3. The resin composition according to claim 1 or 2, wherein an area ratio of a polymer component having a glass transition temperature of 30 ℃ or higher to a polymer component having a glass transition temperature of-10 ℃ or lower in a transmission electron microscope image of a cross section of the polymer particle is 5/95 to 70/30.

4. The resin composition according to any one of claims 1 to 3, wherein a coating film containing the same polymer component as the island component is formed on the surface of the polymer particle.

5. The resin composition according to any one of claims 1 to 4, wherein the polymer particles are aggregated to form secondary particles.

6. The resin composition according to claim 5, wherein the polymer particles have an average primary particle diameter of 0.2 to 1 μm.

7. The resin composition according to claim 5 or 6, wherein the polymer particles have an average secondary particle diameter of 1.1 to 10 μm.

8. The resin composition according to any one of claims 1 to 7, wherein the polymer particles comprise an acrylic polymer or a conjugated diene polymer.

9. The resin composition according to any one of claims 1 to 8, wherein the mass ratio of the polymer particles to the ethylene-vinyl alcohol copolymer is from 1/99 to 40/60.

10. The resin composition according to any one of claims 1 to 9, wherein the ethylene-vinyl alcohol copolymer has an ethylene content of 20 to 50 mol%.

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

Technical Field

The present invention relates to a resin composition in which polymer particles are dispersed in a matrix of an ethylene-vinyl alcohol copolymer. Further, it relates to a multilayer structure having a layer comprising such a resin composition.

Background

Ethylene-vinyl alcohol copolymers (hereinafter, sometimes abbreviated as EVOH) are widely used as packaging materials for foods, medicines, medical instruments, clothing, and the like because they exhibit excellent gas barrier properties against gases such as oxygen and also have excellent melt-moldability. Furthermore, EVOH is also used for fuel tanks, pipes, and the like because it has excellent barrier properties against fuels such as gasoline. However, EVOH is a resin having low flexibility, and therefore, the impact resistance of the obtained molded article may be insufficient.

As a method for improving the flexibility of the resin, there are known: a method of adding polymer particles having a core-shell structure comprising a rubber layer (core) and a hard layer (shell) covering the periphery thereof to a resin. Patent document 1 describes: a thermoplastic resin composition containing EVOH and multilayer-structured polymer particles having an acrylic rubber or the like containing butyl acrylate as a main component as an inner layer (core) and polymethyl methacrylate or the like as an outermost layer (shell) is excellent in gas barrier properties and flexibility, and is useful as a bottle or the like requiring impact resistance.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 9-249782.

Disclosure of Invention

Problems to be solved by the invention

However, a molded article obtained using the thermoplastic resin composition described in patent document 1 has room for improvement in impact resistance, particularly impact resistance at low temperatures. The present invention has been made to solve the above problems, and an object thereof is to provide a resin composition having excellent gas barrier properties and impact resistance.

Means for solving the problems

The above object is achieved by providing a resin composition in which polymer particles having a sea-island structure are dispersed in a matrix of EVOH, one of the sea component and the island component having a glass transition temperature (hereinafter sometimes abbreviated as Tg) of 30 ℃ or higher and the other having a Tg of-10 ℃ or lower.

At this time, it is preferable that: the Tg of the sea component is-10 ℃ or lower, and the Tg of the island component is 30 ℃ or higher. The area ratio of the polymer component having a Tg of 30 ℃ or higher to the polymer component having a Tg of-10 ℃ or lower in a transmission electron microscope image of a cross section of the polymer particle is preferably 5/95 to 70/30. It is also preferable that a coating film containing the same polymer component as the island component is formed on the surface of the polymer particle.

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

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

A multilayer structure having a layer comprising the aforementioned resin composition is a suitable embodiment of the present invention.

Effects of the invention

The resin composition of the present invention has high gas barrier properties and is excellent in impact resistance, particularly impact resistance at low temperatures. Therefore, the resin composition is useful as a packaging material for foods, medicines, medical instruments, clothing and the like, and is also useful as a tank, a pipe and the like for fuel, which require impact resistance at low temperatures.

Drawings

FIG. 1 is a transmission electron microscope image of a cross section of polymer particles in a resin composition pellet in example 1.

FIG. 2 is a transmission electron microscope image of a cross section of polymer particles in the resin composition pellet in example 1.

Detailed Description

The resin composition of the present invention is a resin composition in which polymer particles having a sea-island structure are dispersed in a matrix of EVOH, wherein one of the sea component and the island component has a Tg of 30 ℃ or higher and the other has a Tg of-10 ℃ or lower.

（EVOH）

The EVOH used in the present invention is a copolymer having an ethylene unit and a vinyl alcohol unit. EVOH is generally obtained by saponifying an ethylene-vinyl ester copolymer. The EVOH may contain a vinyl ester unit. The production of the ethylene-vinyl ester copolymer and the saponification thereof can be carried out by a known method. Examples of the vinyl ester used for producing the ethylene-vinyl ester copolymer include vinyl esters of fatty acids such as vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate, and vinyl versatate, and among them, vinyl acetate is preferable.

The ethylene unit content of the EVOH is preferably 20 mol% or more, and more preferably 25 mol% or more. When the ethylene unit content is less than 20 mol%, there is a fear that the thermal stability of the resin composition is lowered or the impact resistance is lowered due to a reduction in flexibility. On the other hand, the ethylene unit content of the EVOH is preferably 50 mol% or less, more preferably 35 mol% or less. If the ethylene unit content of the EVOH exceeds 50 mol%, the gas barrier property of the resin composition may be lowered. The ethylene unit content and the saponification degree of EVOH can be determined by a Nuclear Magnetic Resonance (NMR) method.

The saponification degree of EVOH is preferably 90 mol% or more, more preferably 95 mol% or more, and still more preferably 99 mol% or more. When the saponification degree of EVOH is 90 mol% or more, the gas barrier property, thermal stability and moisture resistance are further improved. The saponification degree of EVOH is usually 99.97 mol% or less, preferably 99.94 mol% or less.

The EVOH may have a unit derived from a monomer other than ethylene, vinyl ester, and a saponified product thereof, within a range not impairing the object of the present invention. The content of the unit derived from another monomer 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, based on the total monomer units in the EVOH. When the EVOH has a unit derived from another monomer, the content thereof is preferably 0.05 mol% or more, more preferably 0.10 mol% or more, based on the total monomer units in the EVOH. Examples of the other monomer include unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid and itaconic acid, anhydrides and salts thereof, and monoalkyl esters and dialkyl esters thereof; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefin sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, and salts thereof; vinyl silane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β -methoxy-ethoxy) silane and γ -methacryloxypropylmethoxysilane; alkyl vinyl ethers, vinyl ketones, N-vinyl pyrrolidone, vinyl chloride, vinylidene chloride, and the like.

The MFR (melt flow rate) (measured at 210 ℃ under a load of 2160 g) of the EVOH is preferably 0.1 to 100g/10 min. When the MFR of the EVOH exceeds 100g/10 min, the strength of the resulting molded article may decrease. The MFR of the EVOH is more preferably 50g/10 min or less, still more preferably 30g/10 min or less. On the other hand, when the MFR of the EVOH is less than 0.1g/10 min, melt molding may be difficult. The MFR of the EVOH is more preferably 0.5g/10 min or more.

EVOH may be used alone in 1 kind, or in combination with 2 or more kinds.

(Polymer particles)

The polymer particles used in the present invention have an island-in-sea structure. Fig. 1 and 2 are transmission electron microscope images of a cross section of polymer particles in a resin composition pellet of example 1 described later. As shown in fig. 1 and 2, the polymer particles (primary particles) of the present invention have an island-in-sea structure having a plurality of island components (dark portions) and sea components (bright portions) around them. The sea-island structure in the present invention means a core-shell structure having a plurality of island components, excluding a core whose periphery is covered with a shell. It is preferable that a plurality of polymer particles (primary particles) are aggregated in a matrix of EVOH to form secondary particles.

Fig. 1 and 2 are transmission electron microscope images of cross sections of polymer particles that have been electronically dyed using a phosphomolybdic acid liquid, the island component (dark portion) containing a polymer component having methyl methacrylate with a Tg of 106 ℃ as a main component, and the sea component (light portion) containing a polymer component having butyl acrylate with a Tg of-39 ℃ as a main component. In the present invention, it is necessary that one of the sea component and the island component constituting the polymer particles has a Tg of 30 ℃ or higher and the other has a Tg of-10 ℃ or lower. In the polymer particles shown in FIGS. 1 and 2, the dark portion is a polymer component having a Tg of 30 ℃ or higher, and the bright portion is a polymer component having a Tg of-10 ℃ or lower, but the dark portion and the bright portion may be reversed depending on the kind of the polymer component constituting the polymer particles.

The polymer particles may have a Tg of-10 ℃ or lower for the sea component and a Tg of 30 ℃ or higher for the island component, or may have a Tg of-30 ℃ or higher for the sea component and a Tg of-10 ℃ or lower for the island component. Of importance in the polymer particles of the present invention are: an island-in-sea structure is formed in which a plurality of polymer components (island components) are dispersed in one polymer component (sea component). Surprisingly: the polymer particles having such a sea-island structure can greatly improve the impact resistance of a molded article comprising a resin composition containing EVOH, compared with conventional polymer particles having a core-shell structure. From the viewpoint of further improving the impact resistance, it is preferable that the Tg of the sea component is-10 ℃ or lower and the Tg of the island component is 30 ℃ or higher.

In a transmission electron microscope image of a cross section of the polymer particle, the area ratio (high Tg component/low Tg component) of a polymer component having a Tg of 30 ℃ or higher to a polymer component having a Tg of-10 ℃ 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 handling properties when recovering the polymer particles may be lowered. The area ratio (high Tg component/low Tg component) is more preferably 10/90 or more. 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 will be insufficient. The area ratio (high Tg component/low Tg component) is more preferably 60/40 or less, and still more preferably 50/50 or less. The area ratio (high Tg component/low Tg component) was calculated by binarizing a transmission electron microscope image of the cross section of the polymer particle and then determining the area ratio of the dark portion and the light portion in the polymer particle. The binarized transmission electron microscope image was obtained by the method described in examples.

Fig. 1 and 2 show that the same dark portions as those of the island component are formed on the outer periphery of the polymer particle. From the viewpoint of the handling properties of the polymer particles, etc., it is preferable that: the polymer particle of the present invention has an island-in-sea structure, and a coating film containing the same polymer component as the island component is formed on the surface of the polymer particle. When such a coating is formed, the ratio of the thickness of the coating to the average primary particle diameter of the polymer particles (coating thickness/average primary particle diameter) in the 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 diameter) is more preferably 0.003 or more. On the other hand, the ratio (coating thickness/average primary particle diameter) is more preferably 0.045 or less. The average primary particle diameter of the polymer particles, the thickness of the coating film, and the average secondary particle diameter of the polymer particles described later are calculated from transmission electron microscope images of the cross section of the same polymer particles as those used for calculating the area ratio (high Tg component/low Tg component). The particle diameter of the polymer particles can be determined as an arithmetic average of the maximum length of the particles, and the average particle diameter is calculated from the number of particles included in the observation field and the particle diameter thereof.

The area ratio of the total area of island components present in a region in which the distance from the center of gravity of the cross section of the polymer particle (primary particle) to the distance from the center of gravity to the outline of the cross section is 75% or less to the total area of island components present in the cross section is preferably 0.1 or more. In this manner, by including the island component in the center portion of the polymer particle, the impact resistance of the resin composition is further improved. The area ratio is preferably 0.9 or less.

Examples of the polymer component having a Tg of-10 ℃ or lower constituting the polymer particles include acrylic polymers; olefin polymers such as ethylene-butene copolymers and ethylene-propylene copolymers; a urethane polymer; styrene polymers such as styrene-ethylene/butylene-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, hydrogenated products thereof, and the like, and silicone polymers such as polyorganosiloxanes; an ethylene-based ionomer copolymer; polybutadiene, polyisoprene, butadiene-isoprene copolymers, polychloroprene, and the like. These may be used alone or in combination of two or more. Among them, the polymer component having a Tg of-10 ℃ or lower is preferably an acrylic polymer or a conjugated diene polymer.

The acrylic polymer is produced by polymerizing an acrylic ester. Examples of the acrylic ester used for synthesizing the acrylic polymer include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and octyl acrylate. Among them, butyl acrylate and ethyl acrylate are preferably polymerized.

When synthesizing the acrylic polymer, if necessary, a monofunctional polymerizable monomer other than the acrylic acid ester may be copolymerized in a range where the Tg of the obtained polymer component is-10 ℃ or lower. Examples of the other monofunctional polymerizable monomer to be copolymerized include methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, phenyl methacrylate, benzyl methacrylate, naphthyl methacrylate, and isobornyl methacrylate; aromatic vinyl compounds such as styrene and α -methylstyrene; acrylonitrile, and the like. The content of other monofunctional monomer units in the acrylic polymer is preferably 20% by mass or less with respect to the total monomer units.

When producing the conjugated diene polymer, if necessary, a monofunctional polymerizable monomer other than the conjugated diene may be copolymerized in a range where the Tg of the obtained polymer component is-10 ℃ or lower. Examples of the other monofunctional polymerizable monomer to be copolymerized include the monomers described above as the other monofunctional polymerizable monomer to be copolymerized with the acrylic ester in the production of the acrylic polymer. The content of the other monofunctional polymerizable monomer unit in the conjugated diene polymer is preferably 20% by mass or less with respect to the total monomer units.

The polymer component having a Tg of-10 ℃ or lower preferably has a molecular chain structure crosslinked to exhibit rubber elasticity, and the molecular chain of the polymer component having a Tg of-10 ℃ or lower and the molecular chain of the polymer component having a Tg of 30 ℃ or higher adjacent thereto are preferably grafted by a chemical bond. For this reason, in the polymerization of the monomer for forming the polymer component having a Tg of-10 ℃ or lower, it is sometimes preferable to use a small amount of a polyfunctional polymerizable monomer in combination as a crosslinking agent or a grafting agent.

The polyfunctional polymerizable monomer used for forming the polymer component having a Tg of-10 ℃ or lower is a monomer having 2 or more carbon-carbon double bonds in the molecule, and includes, for example, esters of 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 butylene glycol; and esters of dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and maleic acid with unsaturated alcohols. Specific examples thereof 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, hexanediol di (meth) acrylate, and the like. Among them, allyl methacrylate and ethylene glycol di (meth) acrylate can be suitably used. It should be noted that the term "di (meth) acrylate" refers to a generic term of "diacrylate" and "dimethacrylate". These may be used alone or in combination of two or more.

The content of the polyfunctional polymerizable monomer unit in the polymer component having a Tg of-10 ℃ or lower is preferably 10% by mass or lower with respect to the total monomer units. If the content of the polyfunctional polymerizable monomer unit is too large, the impact resistance of the resulting molded article may be lowered. When a monomer containing a conjugated diene compound as a main component is used, it itself functions as a crosslinking point or a grafting point, and therefore, it is not always necessary to use a polyfunctional polymerizable monomer in combination.

Examples of the radical polymerizable monomer used for synthesizing the polymer component having a Tg of 30 ℃ or higher constituting the polymer particles include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate; methacrylates having an alicyclic skeleton such as cyclohexyl methacrylate, isobornyl methacrylate, and adamantyl methacrylate; methacrylic acid esters having an aromatic ring such as phenyl methacrylate; aromatic vinyl ester compounds such as styrene and α -methylstyrene; acrylonitrile, and the like. These monomers may be used alone or in combination of two or more. Preferred examples of the radical polymerizable monomer include methyl methacrylate and styrene; or a combination of 2 or more radically polymerizable monomers containing the above as a main component.

In the synthesis of a polymer component having a Tg of 30 ℃ or higher, it is sometimes preferable to use a small amount of a polyfunctional polymerizable monomer. Examples of the polyfunctional polymerizable monomer used in this case include those described above as being used for forming a polymer component having a Tg of-10 ℃ or lower. The content of the polyfunctional polymerizable monomer unit in the polymer component having a Tg of 30 ℃ or higher in the polymer particles is preferably 10% by mass or less with respect to the total monomer units.

The polymer particles preferably have at least 1 functional group having reactivity or affinity for hydroxyl groups. This improves the dispersibility of the polymer particles in the matrix of EVOH in the obtained resin composition, and further improves the gas barrier property. Such polymer particles can be obtained by using, as a part of monomers, a polymerizable compound having a functional group reactive or having affinity for a hydroxyl group in a polymerization reaction for producing the polymer particles. Here, the functional group may be protected with a protecting group which does not impair the object of the present invention and which is released when EVOH is mixed with polymer particles.

Examples of the radical polymerizable compound having a functional group having reactivity or affinity with a hydroxyl group include: unsaturated compounds having a functional group capable of reacting with a hydroxyl group in EVOH to form an intermolecular bond such as a chemical bond or a hydrogen bond when EVOH is mixed with the polymer particles. Examples of the functional group having reactivity or affinity with a hydroxyl group include acid groups such as a hydroxyl group, an epoxy group, an isocyanate group (-NCO), and a carboxyl group; acid anhydride groups such as maleic anhydride groups, and the like.

Examples of the unsaturated compound having the functional group include polymerizable compounds having a hydroxyl group 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, trans-4-hydroxy-2-butene; epoxy group-containing polymerizable compounds such as glycidyl (meth) acrylate, allyl glycidyl ether, 3, 4-epoxybutene, 4, 5-epoxypentyl (meth) acrylate, 10, 11-epoxyundecyl methacrylate, and p-glycidyl styrene; and carboxylic acids such as (meth) acrylic acid, crotonic acid, cinnamic acid, itaconic acid, maleic acid, citraconic acid, aconitic acid, mesaconic acid, and methylenemalonic acid. It should be noted that the term "di (meth) acrylate" refers to a general term of "diacrylate" and "dimethacrylate", and the term "(meth) acrylic acid" refers to a general term of "acrylic acid" and "methacrylic acid".

The amount of the radical polymerizable compound having a functional group reactive or compatible with a hydroxyl group is preferably 0.01 to 75% by mass, more preferably 0.1 to 40% by mass, based on the total amount of the monomers used for producing the polymer particles. Examples of the radical polymerizable compound having a protected functional group include t-butyl methacryloylcarbamate and the like.

The functional group may be present in any polymer component under conditions that allow the functional group to substantially react with a hydroxyl group in EVOH or to form an intermolecular bond. A part of the polymer particles in the resin composition may form a chemical bond between EVOH, and it is particularly preferable that a functional group having reactivity or affinity with hydroxyl groups be present in the molecular chain on the surface of the polymer particles.

The average primary particle diameter of the polymer particles in the resin composition is preferably 0.2 to 5 μm. When the average primary particle diameter of the polymer particles is less than 0.2 μm, in the case where the polymer particles are dry-blended with EVOH and melt-extruded to obtain resin composition pellets, the average secondary particle diameter of the polymer particles in the pellets tends to become excessively large. Here, the secondary particles refer to particles obtained by aggregating primary particles. The average primary particle diameter is more preferably 0.3 μm or more, and still more preferably 0.35 μm or more. On the other hand, when the average primary particle diameter exceeds 5 μm, the number of primary particles constituting 1 secondary particle may be reduced, which may result in a decrease in gas barrier property. The average primary particle diameter is more preferably 3 μm or less, still more preferably 2 μm or less, particularly preferably 1 μm or less, and most preferably 0.8 μm or less.

The average secondary particle diameter of the polymer particles in the resin composition is preferably 1 to 10 μm. In this manner, the impact resistance of the resulting molded article is further improved by forming aggregates of small polymer particles in the resin composition. The average secondary particle diameter is more preferably 1.1 μm or more, still more 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, still more preferably 6 μm or less, and particularly preferably 5 μm or less. Examples of the method for adjusting the average secondary particle diameter of the polymer particles to a predetermined range include a method of adjusting the screw rotation speed during dry blending, a method of increasing the amount of the second-stage graft component to be added during synthesis of the polymer particles, and the like.

The method for producing the polymer particles is not particularly limited, and the polymer particles can be produced by the following method, for example. First, a polymer component (rubber latex) having a Tg of-10 ℃ or lower is obtained by emulsion polymerization. The emulsion polymerization is carried out according to the means generally used by those skilled in the art. Then, it is preferable to aggregate the obtained rubber latex. This further improves impact resistance. Examples of the aggregating agent used for the aggregation of the rubber latex include organic acids such as tartaric acid and salts thereof; inorganic acids such as hydrochloric acid and sulfuric acid, and salts thereof.

If necessary, the polymer component (rubber latex) having a Tg of-10 ℃ or lower is aggregated and then the polymer component is graft-polymerized with a radical polymerizable monomer to form a polymer component having a Tg of 30 ℃ or higher. The graft polymerization may be carried out in one stage or in a plurality of stages. The total polymerization time is preferably 5 to 100 hours. It can be considered that: by the long-term polymerization, the radically polymerizable monomer penetrates into the polymer component having a Tg of-10 ℃ or lower, and thus the sea-island structure is easily formed. After the graft polymerization, the polymer particles are isolated and obtained from the copolymer latex according to a method generally used by those skilled in the art (for example, coagulation, drying, etc.).

In the emulsion polymerization method, a general polymerization initiator can be used. Examples thereof 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); oil-soluble initiators such as azobisisobutyronitrile. These may be used alone or in combination of 2 or more. These initiators can be used as a general redox type polymerization initiator used in combination with a reducing agent such as sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, iron sulfate, sodium ethylenediaminetetraacetate complex, or sodium pyrophosphate.

The emulsifier used in the emulsion polymerization method is not particularly limited, and a usual emulsifier for emulsion polymerization can be used. Examples thereof include sulfate ester surfactants such as sodium alkyl sulfate; sulfonate surfactants such as sodium alkylbenzenesulfonate, sodium alkylsulfonate, dioctyl sodium sulfosuccinate, and dioctyl sodium sulfosuccinate; phosphate surfactants such as sodium alkylphosphate esters and sodium polyoxyethylene alkylether phosphate esters; anionic surfactants such as N-acyl sarcosinate surfactants such as sodium N-lauroyl sarcosinate and fatty acid surfactants such as potassium oleate. The sodium salt may be other alkali metal salts such as potassium salt, or ammonium salts. These emulsifiers may be used alone or in combination of 2 or more. Furthermore, nonionic surfactants represented by polyoxyalkylene compounds or alkyl-substituted or aryl-substituted compounds of terminal hydroxyl groups thereof may be used or partially used in combination. Among them, from the viewpoint of polymerization reaction stability and particle diameter controllability, a sulfonate surfactant or a phosphate surfactant is preferable, and among them, a dioctyl sulfosuccinate, or a polyoxyethylene alkyl ether phosphate is more preferably used.

(resin composition)

The mass ratio of the polymer particles to the EVOH in the resin composition (polymer particles/EVOH) is preferably in the range of 1/99-40/60. When the mass ratio (polymer particles/EVOH) is 1/99 or more, the impact resistance of the resin composition is further improved. The mass ratio (polymer pellet/EVOH) is more preferably 3/97 or more, and still more preferably 5/95 or more. When the mass ratio (polymer pellet/EVOH) is 40/60 or less, the gas barrier property is further improved. The mass ratio (polymer pellet/EVOH) is more preferably 30/70 or less, and still more preferably 25/75 or less.

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

The resin composition may contain other additives than the EVOH and the polymer particles within a range not impairing the effects of the present invention. Examples of such other additives include resins other than EVOH and the polymer component constituting the polymer particles, metal salts, acids, boron compounds, antioxidants, plasticizers, fillers, antiblocking agents, lubricants, stabilizers, surfactants, colorants, ultraviolet absorbers, antistatic agents, drying agents, crosslinking agents, fillers, reinforcing materials such as various fibers, and the like. Among them, from the viewpoint of thermal stability of the resin composition and adhesiveness to other resins, metal salts and acids are preferable.

The metal salt is preferably an alkali metal salt from the viewpoint of further improving the interlayer adhesiveness of the multilayer structure, and is preferably an alkaline earth metal salt from the viewpoint of thermal stability. When the resin composition contains a metal salt, the content thereof is preferably 1 to 10000ppm in terms of metal element. The content of the metal salt is more preferably 5ppm or more, further preferably 10ppm or more, particularly preferably 20ppm or more in terms of the metal element. On the other hand, the content of the metal salt is more preferably 5000ppm or less, further preferably 1000ppm or less, particularly preferably 500ppm or less in terms of the metal element. As a method for measuring the content of the metal salt, for example, a method for quantifying a sample obtained by freeze-crushing a dry EVOH pellet by an ICP emission spectrometer can be cited.

The acid is preferably a carboxylic acid compound or a phosphoric acid compound from the viewpoint of improving thermal stability during melt molding. When the resin composition contains a carboxylic acid compound, the content thereof is preferably 1 to 10000 ppm. The content of the carboxylic acid compound is more preferably 10ppm or more, and still more preferably 50ppm or more. On the other hand, the content of the carboxylic acid compound is more preferably 1000ppm or less, and still more preferably 500ppm or less. As a method for measuring the acid content, for example, a neutralization titration method can be cited.

When the resin composition contains a phosphoric acid compound, the content thereof is preferably 1 to 10000 ppm. The content of the phosphoric acid compound is more preferably 10ppm or more, and still more preferably 30ppm or more. On the other hand, the content of the phosphoric acid compound is more preferably 1000ppm or less, and still more preferably 300ppm or less. As a method for measuring the content of the phosphoric acid compound, for example, a method for quantifying a sample obtained by freeze-crushing a dry EVOH pellet by an ICP emission spectrometer can be mentioned.

When the resin composition contains a boron compound, the content thereof is preferably 1 to 2000 ppm. The content of the boron compound is more preferably 10ppm or more, and still more preferably 50ppm or more. On the other hand, the content of the boron compound is more preferably 1000ppm or less, and still more preferably 500ppm or less. When the content of the boron compound in the resin composition is within the above range, the thermal stability at the time of melt molding is further improved. The content of the boron compound can be measured by the same method as that for the above-mentioned phosphoric acid compound.

As a method for incorporating the phosphoric acid compound, the carboxylic acid compound or the boron compound into the resin composition, for example, a method of adding these compounds to an EVOH composition and kneading them at the time of producing pellets of the resin composition or the like can be suitably employed. Examples of the method of adding these compounds to the EVOH composition include a method of adding a dry powder, a method of adding a paste impregnated with a solvent, a method of adding a suspension suspended in a liquid, a method of adding a solution dissolved in a solvent, and a method of immersing EVOH pellets in a solution. Among them, from the viewpoint of uniformly dispersing the phosphoric acid compound, the carboxylic acid compound or the boron compound, a method of adding a solution dissolved in a solvent or a method of immersing EVOH pellets in a solution is preferable. As the solvent, for example, water can be suitably used from the viewpoints of solubility of the additive, cost, ease of handling, safety of the working environment, and the like.

The resin composition can be obtained by mixing EVOH, polymer particles, and other additives as necessary. As a method for mixing them, a known method for mixing resins can be used. When the melt-kneading method is used, EVOH, polymer pellets, and if necessary, an antioxidant, a stabilizer, a dye, a pigment, a plasticizer, a lubricant, a filler, other resins, etc. are added, and then melt-kneading is performed using a screw extruder, etc., at 180 to 300 ℃.

The polymer particles used for producing the resin composition may be, for example, particles in which the surfaces of the polymer particles are fused with each other, as long as the polymer particles are sufficiently dispersed into particles when mixed with EVOH.

(molded article)

A molded article comprising the resin composition described above is a suitable embodiment of the present invention. The resin composition of the present invention is melt-molded to form various molded articles such as films, sheets, containers, pipes, fibers, and the like. As the melt molding method of the resin composition, a known method can be used, and extrusion molding, inflation extrusion, blow molding, injection molding, melt spinning, and the like can be used. The melting temperature varies depending on the melting point of EVOH, but is preferably 150 to 270 ℃. In this case, the resin composition of the present invention may be once pelletized and then subjected to molding, or EVOH, polymer pellets and, if necessary, other additives may be dry-blended and directly subjected to molding. These molded articles may be pulverized for reuse and then molded again. Further, the film, sheet, fiber, or the like may be subjected to secondary processing by uniaxial stretching, biaxial stretching, or thermoforming.

As the blow molding method, both extrusion blow molding and injection blow molding can be used. As the extrusion blow molding, it is also possible to perform blow molding by cutting and cooling an extrusion-molded tube in advance and then heating it, but it is suitable for a so-called direct blow molding method in which an extruded tubular molten parison is directly blow-molded. Further, as the injection blow molding, there is a method of performing injection molding of a bottomed parison in advance and performing blow molding in a high temperature state in the middle of cooling, or performing blow molding by reheating after cooling.

The molded article of the present invention may be a single layer or a multilayer, and is preferably a multilayer structure having a layer containing the resin composition. The thickness of the multilayer structure is not particularly limited, but is usually 10 to 5000 μm. The ratio of the thickness of the resin composition layer to the thickness of the multilayer structure (resin composition layer/multilayer structure) is preferably 0.02 to 0.2. If the thickness ratio (resin composition layer/multilayer structure) exceeds 0.2, moldability may deteriorate and cost may increase. On the other hand, if the thickness ratio (resin composition layer/multilayer structure) is less than 0.02, there is a concern that the gas barrier property may be lowered.

The layer structure of the multilayer structure is not particularly limited, and when a thermoplastic resin layer other than EVOH is denoted by a, a resin composition layer is denoted by B, and an adhesive resin layer is denoted by C, the layer structure may be represented by a/B, A/B/A, A/C/B, A/C/B/C/A, A/B/a/B/A, A/C/B/C/a. It may be just as well that other layers are further added to them. When a plurality of other thermoplastic resin layers are provided, different layers may be used, or the same layer may be used. Further, a layer of a recycled resin containing scraps generated during molding, irregular molded articles, and the like may be separately provided, or a layer containing a blend of the recycled resin and another thermoplastic resin may be used as the other thermoplastic resin layer.

As the resin used in the adhesive resin layer, for example, a urethane-based, polyester-based one-liquid or two-liquid curable adhesive; a polyolefin having a carboxyl group, a carboxylic anhydride group or an epoxy group. Among these, polyolefins having a carboxyl group, a carboxylic anhydride group, or an epoxy group are more preferable from the viewpoint of excellent adhesiveness to EVOH and adhesiveness to polyolefin.

Examples of the polyolefin having a carboxyl group include polyolefins obtained by copolymerizing acrylic acid or methacrylic acid, and all or a part of the carboxyl groups contained in the polyolefin may be present in the form of a metal salt, as represented by ionomers. Examples of the polyolefin having a carboxylic anhydride group include polyolefins graft-modified with maleic anhydride or itaconic acid. Examples of the polyolefin resin containing an epoxy group include polyolefins obtained by copolymerizing glycidyl methacrylate. Among these, polyolefins modified with carboxylic acid anhydride such as maleic anhydride are preferable from the viewpoint of excellent adhesiveness, and polyethylene is particularly preferable.

Examples of the thermoplastic resin used for the other thermoplastic resin layer include polyolefins such as polyethylene (linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene), ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene, propylene- α -olefin copolymer, polybutene, and polypentene; polyesters such as polyethylene terephthalate; a polyester elastomer; polyamides such as nylon 6 and nylon 66; polystyrene; polyvinyl chloride; polyvinylidene chloride; an acrylic resin; a vinyl ester resin; a polyurethane elastomer; a polycarbonate; chlorinated polyethylene; chlorinated polypropylene. Among them, preferred are polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene, and polyester.

As the method for producing the multilayer structure, a known method can be used, and a method such as coextrusion molding, coinjection molding, or extrusion coating can be used.

As a method for producing a blow molded container including a multilayer structure, coextrusion blow molding and coinjection blow molding can be suitably employed. As a method of coextrusion blow molding, a so-called direct blow molding method can be mentioned as a suitable method: the resin composition, the other thermoplastic resin, and, if necessary, the adhesive resin are supplied to the respective extruders using a multi-layer extruder having at least 2 extruders, and are kneaded and melt-extruded, respectively, so that the respective layers are extruded so as to be closely joined together inside a die for molding a multi-layer parison or outside the die immediately after being discharged from the die, thereby obtaining a multi-layer parison in a tubular shape, and then the parison is blow-molded in a molten state, thereby obtaining a multi-layer container.

The molded article obtained using the resin composition of the present invention has high gas barrier properties and is excellent in impact resistance, particularly impact resistance at low temperatures. Therefore, the molded article is useful as a packaging material for foods, medicines, medical instruments, clothing and the like, and is also useful as a tank, a pipe or the like for fuel, which requires impact resistance at low temperatures.

Examples

The present invention will be described more specifically with reference to examples.

[ Structure Observation of Polymer particles ]

Pretreatment and seed dyeing

The resin composition pellets obtained in each of examples and comparative examples were cut with an ultra-thin slicer (model: Ultracut S/FC-S) manufactured by ライカ to prepare an ultra-thin slice for transmission electron microscope observation. The cutting conditions were as follows.

Sample preparation: -100 deg.C

A cutter: -100 deg.C

Cutting speed: 0.4 to 1.0mm/s

Cutting thickness set value: 85nm

Thickness: 85 nm.

The ultrathin section obtained was collected on a copper mesh (1000 mesh), and electron staining was performed using a phosphomolybdic acid liquid.

Structural observation

Morphological observation was performed under the following conditions. For structural observation of polymer particles, the particles filled with LaB are used₆A transmission electron microscope (model: HT7700, corresponding to 3 DTEM) manufactured by Hitachi ハイテクノロジーズ of Electron gun.

Acceleration voltage: 100KV

LaB₆Electron beam irradiation amount: 10 muA

Spot size of electron beam: 1 μm

Aperture of condenser: 0.1mm (No. 2)

Movable iris aperture of objective lens for 3D: 0.16mm (No. 3)

CCD camera for photography: bottom mounted cameras (model: XR81B, 8 megapixel cameras) made by AMT corporation.

Binarization method

The calculation of the light area, the dark area, the average primary particle diameter, the average secondary particle diameter, and the coating film thickness was performed by image analysis of a map image in which all the fields of view were occupied by the cross-section of the resin composition pellet. Image-Pro Plus manufactured by ローパー was used as Image analysis software. In the image analysis, first, the average primary particle diameter, the average secondary particle diameter, and the areas of the light and dark portions of the polymer particles are calculated by tracing the contour of the particle portion in the map image. Tracking of the grain contours is performed for the contrast-adjusted map. This contrast adjustment is automatically implemented by using the "best match of contrast" instruction of the image analysis software. Further, the particle portion is separated/extracted from the background (LSCF area) by using the binarization "Segmentation" instruction. Specifically, the image is converted into a black-and-white image in which the white portion of the contrast-adjusted image is a bright portion, and thereby binarized.

Then, the total of white portions in the polymer particles (primary particles) in the binarized image is defined as a bright portion area, and the total of black portions is defined as a dark portion area. Using the binarized map image, the total area of dark portions (island components) present in a region where the distance from the center of gravity of the cross section of the polymer particles (primary particles) is 75% or less with respect to the distance from the center of gravity to the outline of the cross section (this region is shown in fig. 2) was obtained. Further, the thickness of the coating film (dark portion) on the surface of the polymer particle (primary particle) is determined using the binarized map image. The areas of the bright portion and the dark portion are obtained as an arithmetic average of the number of particles included in the observation field.

The average primary particle diameter and the average secondary particle diameter of the polymer particles are determined as an arithmetic average of the maximum length between the outlines of the particles, and the average particle diameter is calculated from the number of particles included in the observation field and the particle diameter thereof.

[ Oxygen Transmission Rate (OTR) ]

Production of Single-layer film

The resin composition pellets obtained in examples and comparative examples were subjected to film formation using a single-screw extrusion apparatus (Toyo Seiki Seisaku-Sho Co., Ltd., D2020, D (mm) 20, L/D (20), compression ratio 3.0, screw: full screw) to obtain a single-layer film having a thickness of 20 μm. The extrusion conditions are as follows.

Extrusion temperature: 220 deg.C

Width of the die: 30cm

Temperature of the traction roller: 80 deg.C

Screw rotation speed: 45rpm

Speed of the traction roller: 3.4 m/min.

The obtained monolayer film having a thickness of 20 μm was subjected to humidity conditioning at 20 ℃/65% RH, and then the oxygen permeability (OTR) was measured at 20 ℃/65% RH using an oxygen permeability measuring apparatus (OX-Tran 2/20, manufactured by ModernControl).

[ evaluation of impact resistance ]

Manufacture of blow-molded containers

Using the obtained resin composition pellets, a high-density polyethylene resin [ having a density of 0.96g/cc and an MFR of 0.5g/10 min (measured at 210 ℃ under a load of 2160 g) ] and an adhesive resin ("ADMER GT-6A" manufactured by Mitsui chemical Co., Ltd.), 3 types of 5-layer preforms of (inner) high-density polyethylene/adhesive resin/resin composition/adhesive resin/high-density polyethylene (outer) were discharged at 210 ℃ for 2 hours by a blow molding machine TB-ST-6P manufactured by Suzuo Seiki Seisakusho K.K., and then the operation was interrupted in the heated state for 2 hours. Thereafter, the operation is restarted, and a blow molded container is manufactured after a predetermined time has elapsed. At this time, the inside of the mold was cooled at 15 ℃ for 20 seconds to form a 500mL can (blow molded container) having a total layer thickness of 940 μm [ (inner) high-density polyethylene/adhesive resin/resin composition/adhesive resin/high-density polyethylene (outer) (inner) 400/50/40/50/400 μm (outer) ]. The diameter of the bottom of the tank was 100mm and the height was 400 mm.

Drop test

The 500mL can thus obtained was filled with 400mL of ethylene glycol, and the opening was heat-sealed with a multilayer film of polyethylene 40 μm/aluminum foil 12 μm/polyethylene terephthalate 12 μm, followed by capping. The can was cooled at-40 ℃ for 3 days, and then dropped from a height of 6m with the opening facing upward to confirm whether the can was broken. Similarly, 10 cans were tested, and the impact resistance was evaluated based on the number of cans broken.

Evaluation criteria for impact resistance

A: less than 2 damaged cans

B: the number of damaged cans is more than 2 and less than 4

C: the number of damaged cans is more than 4 and less than 6

D: the number of damaged cans was 6 or more.

[ production of EVOH-1 ]

2kg of an EVOH resin having an ethylene unit content of 32 mol% and a degree of saponification of 99.8 mol% was put into 18kg of a mixed solvent of water/methanol (mass ratio) 40/60 and stirred at 60 ℃ for 6 hours to completely dissolve the EVOH resin. The solution was continuously extruded from a nozzle having a diameter of 4mm into a coagulation bath adjusted to 0 ℃ with water/methanol (90/10 mass ratio) to coagulate EVOH into strands. The strand was introduced into a pelletizer to obtain porous EVOH chips.

The porous EVOH pellets thus obtained were washed with an aqueous acetic acid solution and ion-exchanged water, and then subjected to an impregnation treatment with an aqueous solution containing acetic acid, potassium dihydrogen phosphate, sodium acetate and orthoboric acid. The aqueous solution for treatment was separated from the EVOH pellets and drained, and then the resulting mixture was charged into a hot air dryer and dried at 80 ℃ for 4 hours and further at 100 ℃ for 16 hours to obtain dry EVOH pellets (EVOH-1). The EVOH-1 had an acetic acid content of 150ppm, a sodium ion content of 140ppm, a phosphoric acid compound content of 45ppm in terms of phosphate radical, and a boron compound content of 260ppm in terms of boron. Furthermore, the MFR (ASTM-D1238, 210 ℃, 2160g load) of the EVOH-1 was 3.7g/10 min.

[ production of EVOH-2 and EVOH-3 ]

EVOH-2 and EVOH-3 were produced in the same manner as for EVOH-1, except that EVOH resin (EVOH-2) having an ethylene unit content of 27 mol% and a degree of saponification of 99.9 mol% or EVOH resin (EVOH-3) having an ethylene unit content of 44 mol% and a degree of saponification of 99.9 mol% was used. The contents of acetic acid, sodium ions, phosphoric acid compounds and boron compounds in EVOH-2 and EVOH-3 were the same as those in EVOH-1. Furthermore, the MFR (ASTM-D1238, 210 ℃ C., 2160g load) of EVOH-2 and EVOH-3 was 4.0g/10 min and 3.3g/10 min, respectively.

[ production of Polymer particles-1 ]

The following components were charged into a pressure-resistant vessel equipped with a stirrer, and polymerization was carried out at 45 ℃ for 16 hours to complete the polymerization. The polymerization yield was about 100%.

Rubber component

70 parts by mass of n-butyl acrylate

Ethylene glycol dimethacrylate 0.2 part by mass

0.195 parts by mass of hydrogen peroxide diisopropylbenzene

Ferric sulfate (FeSO)₄・7H₂O) 0.002 part by mass

0.003 portion of sodium ethylene diamine tetracetate

0.049 parts by mass of sodium formaldehyde sulfoxylate

0.9 part by mass of potassium oleate

Sodium pyrophosphate 0.1 part by mass

And 175 parts by mass of distilled water.

0.035 parts by mass of dioctyl sodium sulfosuccinate was added to the total amount of the obtained rubber latex to sufficiently stabilize the latex, and then a 2% by mass aqueous solution of tartaric acid and a 2% by mass aqueous solution of sodium hydroxide were further added gradually to aggregate primary particles at a pH of 7 to 9.

To the resulting rubber latex, the first graft component shown below was added, and polymerization was continued at 45 ℃ for 16 hours. The polymerization yield was about 100%.

First stage graft component

14 parts by mass of methyl methacrylate

Glycidyl methacrylate 3 parts by mass

Ethylene glycol dimethacrylate 0.12 part by mass

0.02 part by mass of hydrogen peroxide diisopropylbenzene

0.01 part by mass of sodium formaldehyde sulfoxylate

0.03 part by mass of dioctyl sodium sulfosuccinate.

To the latex obtained was further added a second stage graft component shown below, and polymerization was continued at 45 ℃ for 16 hours. The polymerization yield was about 100%.

Second stage graft component

13 parts by mass of methyl methacrylate

Ethylene glycol dimethacrylate 0.1 part by mass

0.015 parts by mass of hydrogen peroxide diisopropylbenzene.

The latex thus obtained was subjected to salting out with an aqueous solution of sodium chloride, and post-treatment of filtration, washing with water and drying was carried out to obtain polymer particles-1 containing a multicomponent graft resin.

[ production of Polymer particles-2 ]

Polymer particles-2 were produced in the same manner as for polymer particles-1, except that the amounts of the respective components were changed as described below.

Rubber component

90 parts by mass of n-butyl acrylate

First stage graft component

2 parts by mass of methyl methacrylate

Second stage graft component

5 parts by mass of methyl methacrylate.

[ production of Polymer particles-3 ]

Polymer particles-3 were produced in the same manner as for polymer particles-1, except that the amounts of the respective components were changed as described below.

Rubber component

60 parts by mass of n-butyl acrylate

First stage graft component

19 parts by mass of methyl methacrylate

Second stage graft component

18 parts by mass of methyl methacrylate.

[ production of Polymer particles-4 ]

Polymer particles-4 were produced in the same manner as for polymer particles-1, except that the amounts of the respective components were changed as described below.

Rubber component

40 parts by mass of n-butyl acrylate

First stage graft component

29 parts by mass of methyl methacrylate

Second stage graft component

28 parts by mass of methyl methacrylate.

[ production of Polymer particles-5 ]

Polymer particles-5 were produced in the same manner as for polymer particles-1, except that the amounts of the respective components were changed as described below.

Rubber component

23 parts by mass of n-butyl acrylate

First stage graft component

5 parts by mass of methyl methacrylate

Second stage graft component

4 parts by mass of methyl methacrylate.

[ production of Polymer particles-6 ]

Polymer particles-6 were produced in the same manner as for polymer particles-1, except that the amounts of the respective components were changed as described below.

Rubber component

140 parts by mass of n-butyl acrylate

0.01 part by mass of potassium oleate

First stage graft component

28 parts by mass of methyl methacrylate.

[ production of Polymer particles-7 ]

Polymer particles 7 were produced in the same manner as for polymer particles 1, except that the amounts of the respective components were changed as described below.

First stage graft component

24 parts by mass of methyl methacrylate

Second stage graft component

3 parts by mass of methyl methacrylate.

[ production of Polymer particles-8 ]

Polymer particles-8 were produced in the same manner as for polymer particles-1, except that the amounts of the respective components were changed as described below.

First stage graft component

3 parts by mass of methyl methacrylate

Second stage graft component

24 parts by mass of methyl methacrylate.

[ production of Polymer particles-9 ]

Polymer particles-9 were produced in the same manner as for polymer particles-1, except that styrene was used instead of methyl methacrylate as the first-stage graft component and the second-stage graft component.

[ production of Polymer particles-10 ]

Polymer particles 10 were produced in the same manner as in polymer particle-1, except that the first-stage graft component and the second-stage graft component were not polymerized.

Example 1

190 parts by mass of EVOH, which was an EVOH, and 110 parts by mass of polymer pellets, which were polymer pellets, were dry-blended at a screw speed of 50rpm, and then extruded at a temperature of 200 ℃ using a 30 mm-phi co-rotating twin-screw extruder ("TEX-30N" manufactured by Nippon Steel Co., Ltd.), and the resulting mixture was pelletized to obtain resin composition pellets.

The obtained resin composition pellets were subjected to structural observation by the above-described method. Fig. 1 and 2 show transmission electron microscope images (before binarization) of the cross sections of the polymer particles in the resin composition pellets. From FIGS. 1 and 2, it was confirmed that a plurality of primary particles aggregated in the matrix of EVOH-1 to form a secondary particle of polymer particles-1. The primary particles comprise: a sea component (light part) containing a polymer component mainly composed of n-butyl acrylate having a Tg of-39 ℃ and a plurality of island components (dark part) containing a polymer component mainly composed of methyl methacrylate having a Tg of 106 ℃. The polymer particles 1 had an average primary particle diameter of 0.4 μm and an average secondary particle diameter of 3 μm. A coating film (dark portion) containing the same polymer component as the island component was formed on the surface of the primary particles, and the ratio of the thickness of the coating film to the average primary particle diameter (coating film thickness/average primary particle diameter) was 0.02. The total area of dark portions (island components) present in a region (shown in fig. 2) where the distance from the center of gravity of the cross section of the primary particles is 75% or less with respect to the distance from the center of gravity to the outline of the cross section. The area ratio of the total area of the dark portions (island components) present in the region to the total area of the dark portions (island components) present in the cross section of the primary particle was found to be 0.62. The obtained resin composition pellets were used to evaluate oxygen permeability and impact resistance. The results are shown in Table 1.

Examples 2 to 9

Resin composition pellets were produced and evaluated in the same manner as in example 1, except that the types of the polymer particles used were changed to those shown in table 1. The results are shown in Table 1.

Example 10

Pellets of a resin composition were produced and evaluated in the same manner as in example 1, except that the screw rotation speed in dry blending EVOH and polymer pellets was set to 80 rpm. The results are shown in Table 1.

Example 11

Pellets of a resin composition were produced and evaluated in the same manner as in example 1, except that 170 parts by mass of EVOH and 130 parts by mass of polymer pellets were added, respectively. The results are shown in Table 1.

Examples 12 and 13

Resin composition pellets were produced and evaluated in the same manner as in example 1, except that the kind of EVOH used was changed to those shown in table 1. The results are shown in Table 1.

Comparative example 1

Pellets of the resin composition were produced and evaluated in the same manner as in example 1 except that core-shell particles ("PARALOID EXL-2300G" manufactured by Dow corporation) were used instead of the polymer particles-1. The core-shell particle used herein has a structure in which 1 core is covered around by a shell. The results are shown in Table 1.

Comparative example 2

Pellets of the resin composition were produced and evaluated in the same manner as in example 1, except that the polymer particles 10 were used instead of the polymer particles 1. The results are shown in Table 1.

Comparative example 3

Pellets of a resin composition were produced and evaluated in the same manner as in example 1, except that instead of EVOH-1, Polyamide (PA) (ULTRAMID C40LN manufactured by BASF) was used. The results are shown in Table 1.