Thermoplastic resin molded article and packaging material

Abstract

To provide a thermoplastic resin molding capable of optimizing a maze effect effective for oxygen barrier.SOLUTION: A thermoplastic resin molding includes a resin having water vapor barrier properties, a resin having a functional group and a resin having oxygen barrier properties. The resin having the functional group is a different resin from the resin having water vapor barrier properties. The functional group includes a reactive group that can be bonded with the resin having oxygen barrier properties. A dispersion phase is formed with a core-shell structure in which the resin having the functional group encapsulating the resin having oxygen barrier properties is present as an island in the resin having water vapor barrier properties.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a thermoplastic resin molded body and a packaging material.

Background Art

[0002] For packaging materials (packaging films, packages, containers), various resin films and resin molded bodies with excellent gas barrier properties are used from the viewpoint of protecting the contents. Materials commonly used for packaging materials mainly consist of materials based on olefin resins such as polyethylene (hereinafter "PE") and polypropylene (hereinafter "PP"). These olefin resins have excellent barrier properties against water vapor but are inferior in barrier properties against oxygen. On the other hand, hydrophilic resins such as ethylene-vinyl alcohol copolymer (hereinafter "EVOH") have excellent barrier properties against oxygen but are inferior in barrier properties against water vapor.

[0003] As the barrier properties required for packaging materials, the compatibility of oxygen barrier properties and water vapor barrier properties is mentioned. Conventionally, resins with oxygen barrier properties and resins with water vapor barrier properties have been laminated in multiple layers to obtain barrier properties that are compatible with both oxygen and water vapor. In Patent Document 1, the compatibility of barrier properties is obtained by lamination, but there are problems with the adhesiveness between each of the laminated films and the complication of the manufacturing process.

[0004] In Patent Document 2, a laminate is formed with a polyolefin resin such as PE or PP on the surface layer, EVOH in the intermediate layer, and a compatibilizer such as acid modification as a composite material in MXD nylon. Similar to Patent Document 1, there are problems with adhesiveness and the complication of the manufacturing process.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the mixing of a material having oxygen barrier properties and a material having water vapor barrier properties, which is a method that achieves both oxygen and water vapor barrier properties, there is a problem that sufficient oxygen barrier properties cannot be obtained with a simple melt blend obtained by simply mixing them.

[0007] An object of the present invention is to provide a thermoplastic resin molded body capable of optimizing the maze effect effective for oxygen barrier by dispersing a material excellent in oxygen barrier properties in a material excellent in water vapor barrier properties and controlling the shape of the oxygen barrier resin as the dispersed phase, and a packaging material using the same.

Means for Solving the Problems

[0008] In order to solve the above problems, a thermoplastic resin molded body according to an aspect of the present disclosure and a packaging material using the same include a resin having water vapor barrier properties, a resin having a functional group, and a resin having oxygen barrier properties. The resin having the functional group is a resin different from the resin having water vapor barrier properties, the functional group has a reactive group capable of binding to the resin having oxygen barrier properties, and a core-shell structure in which the resin having the functional group wraps the resin having oxygen barrier properties forms a dispersed phase existing as islands in the resin having water vapor barrier properties.

Effects of the Invention

[0009] For a thermoplastic resin molded body according to an aspect of the present disclosure and a packaging material using the same, by controlling the dispersion shape of an ethylene-vinyl alcohol copolymer having oxygen barrier properties, it is possible to provide a thermoplastic resin molded body having the oxygen barrier properties required for the packaging material and having the impact resistance performance and heat seal performance required for the packaging material, and a packaging material using the same.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0011] An embodiment of the present disclosure will be described with reference to the drawings. Hereinafter, the present invention will be described in detail. Note that the configurations shown in the drawings are schematic, and the sizes, shapes, etc. of each part are exaggerated as appropriate for easy understanding. In addition, the following embodiments illustrate configurations for embodying the technical idea of the present invention, and the technical idea of the present invention is not limited to the following in terms of the material, shape, structure, etc. of the constituent parts. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

[0012] (Configuration of Thermoplastic Resin Molded Body) The basic configuration of the thermoplastic resin molded body according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic diagram for explaining a configuration example of a thermoplastic resin molded body 1 according to the present embodiment. The thermoplastic resin molded body 1 contains a resin having a water vapor barrier property, a resin having a functional group, and a resin having an oxygen barrier property. In particular, the thermoplastic resin molded body 1 in the present embodiment includes a polyolefin-based thermoplastic resin (A) having a water vapor barrier property, a copolymer (B) of an olefin and a functional group-containing monomer, and an ethylene-vinyl alcohol copolymer (C) having an oxygen barrier property. As shown in FIG. 1, in the thermoplastic resin molded body 1, a core-shell structure in which the copolymer (B) of an olefin and a functional group-containing monomer wraps the ethylene-vinyl alcohol copolymer (C) forms a dispersed phase 2 that exists as islands in a continuous phase 3 containing the polyolefin-based thermoplastic resin (A).

[0013] Further, FIG. 2 is a cross-sectional view for explaining a configuration example of the thermoplastic resin molded body 1 according to the present embodiment. In the cross-section of the thickness portion in the molding direction Dm and in the cross-section of the thickness portion in the molding width direction Dw of the thermoplastic resin molded body 1 of the present embodiment, as shown in FIG. 2, the copolymer (B) of an olefin and a functional group-containing monomer encapsulating the ethylene-vinyl alcohol copolymer (C) is dispersed inside the polyolefin-based thermoplastic resin (A) serving as the base phase.

[0014] In addition to the polyolefin-based thermoplastic resin (A), the copolymer (B) of an olefin and a functional group-containing monomer, and the ethylene-vinyl alcohol copolymer (C), additives such as a nucleating agent and a reinforcing filler may be used for the thermoplastic resin molded body 1. Examples of the nucleating agent and the reinforcing filler include talc, silica, clay, montmorillonite, calcium carbonate, lithium aluminum carbonate, alumina, titanium oxide, metals such as aluminum, iron, silver, and copper, hydroxides such as aluminum hydroxide and magnesium hydroxide, cellulose microfibrils, celluloses such as cellulose acetate, fibrous fillers such as glass fiber, polyethylene terephthalate fiber, nylon fiber, polyethylene naphthalate fiber, aramid fiber, vinylon fiber, and polyacrylate fiber, and carbons such as carbon nanotubes. These may be used alone or in combination of two or more.

[0015] In addition, additives such as antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, flame retardants, and flame retardant aids may be blended into the thermoplastic resin molded body 1. Examples of antioxidants include phenolic compounds, organic phosphite compounds, thioether compounds, etc. Examples of heat stabilizers include hindered amine compounds, etc. Examples of ultraviolet absorbers include benzophenone compounds, benzotriazole compounds, benzoate compounds, etc. Examples of antistatic agents include nonionic compounds, cationic compounds, anionic compounds, etc. Examples of flame retardants include halogen-based compounds, phosphorus-based compounds, nitrogen-based compounds, inorganic compounds, boron-based compounds, silicone-based compounds, sulfur-based compounds, red phosphorus-based compounds, etc. Examples of flame retardant aids include antimony compounds, zinc compounds, bismuth compounds, magnesium hydroxide, clay silicates, etc. These may be used alone or in combination of two or more.

[0016] In addition, for the thermoplastic resin molded body 1, additives such as weathering agents, light stabilizers, plasticizers, slip agents, antiblocking agents, antifogging agents, lubricants, pigments, dyes, dispersants, copper corrosion inhibitors, neutralizing agents, anti-foaming agents, weld strength improvers, natural oils, synthetic oils, waxes, etc. may also be used. These may be used alone or in combination of two or more.

[0017] The thermoplastic resin molded body 1 of the present invention may not only be used as a single layer but also as a laminate with other types of resin molded bodies.

[0018] (Continuous phase) The continuous phase 3 is composed of a resin having a water vapor barrier property. As the main material of the continuous phase 3, since the thermoplastic resin molded body 1 is formed into a film by an extruder that can be heated up to 340°C, any general thermoplastic resin can be used, but in order to be suitably used as a packaging material, it is necessary to have appropriate flexibility and good processability. In the present embodiment, the continuous phase 3 is mainly composed of a polyolefin-based thermoplastic resin (A) having excellent water vapor barrier properties.

[0019] 〈Polyolefin-based thermoplastic resin〉 The polyolefin-based thermoplastic resin (A) may be any polymer having a structural unit derived from an olefin, and examples include low-density polyethylene (LDPE) based on olefin, linear low-density polyethylene (LLDPE) obtained by copolymerizing an α-olefin and ethylene, medium-density polyethylene (MDPE), high-density polyethylene (HDPE), polypropylene having a homopolymer, random copolymer, block copolymer, etc., cycloolefin polymer, cycloolefin copolymer obtained by copolymerizing a cycloolefin and an olefin, ethylene-vinyl acetate copolymer obtained by copolymerizing the above olefin and vinyl acetate, and ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA), ethylene-methacrylic acid copolymer (EMAA), etc. obtained by modifying the side chain of an olefin. It is possible to appropriately select and use one or more of them alone or in combination.

[0020] The blending ratio of the polyolefin-based thermoplastic resin (A) is preferably 40% by mass or more and 79.5% by mass or less based on the total mass of the thermoplastic resin molded article 1. When the blending ratio of the polyolefin-based thermoplastic resin (A) is 40% by mass or more, by suppressing the increase in the blending amount of the ethylene-vinyl alcohol copolymer (C), it is possible to prevent a decrease in heat sealability, ensure high flexibility, and improve impact resistance. Also, when the blending ratio of the polyolefin-based thermoplastic resin (A) is 79.5% by mass or less, it is possible to sufficiently secure the blending amount of the ethylene-vinyl alcohol copolymer (C) and improve the barrier property.

[0021] (Dispersed phase) As shown in FIG. 1, the dispersed phase 2 exists so as to be dispersed in the continuous phase 3. The dispersed phase 2 includes a resin having oxygen barrier properties and a resin having functional groups. In the present embodiment, the dispersed phase 2 is composed of an ethylene-vinyl alcohol copolymer (C) having excellent oxygen barrier properties and a copolymer (B) of an olefin and a functional group-containing monomer. As shown in FIG. 1, the dispersed phase 2 is a core-shell structure in which the copolymer (B) of an olefin and a functional group-containing monomer wraps the ethylene-vinyl alcohol copolymer (C).

[0022] 〈Copolymer of Olefin and Functional Group-Containing Monomer〉 Since the copolymer (B) of an olefin and a functional group-containing monomer is a material in which the polyolefin-based thermoplastic resin (A) and the ethylene-vinyl alcohol copolymer (C) described later are incompatible, the interfacial tension between the two polymers is reduced during mixing, and the phase separation structure is stabilized. The copolymer (B) of an olefin and a functional group-containing monomer is a resin different from the polyolefin-based thermoplastic resin (A) constituting the continuous phase 3, and is a copolymer thermoplastic resin having a molecular structure provided with a reactive group capable of bonding to the ethylene-vinyl alcohol copolymer (C), and functions as a compatibilizer that improves the affinity between an olefin resin with poor chemical compatibility and an ethylene-vinyl alcohol copolymer. Examples of the thermoplastic resin functioning as a compatibilizer include ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA), ethylene-vinyl alcohol copolymer (EVOH), ethylene-methacrylic acid copolymer (EMAA), ethylene-methyl methacrylate copolymer (EMMA), maleic acid-modified polyolefin (hereinafter referred to as "PO-g-MAH"), and the like. In the present embodiment, the copolymer (B) of an olefin and a functional group-containing monomer is used as the resin having functional groups, but it is not limited thereto. For example, as the resin having functional groups, a resin having a hydroxyl group, a carbonyl group, or the like can be used.

[0023] The total blending ratio of the polyolefin-based thermoplastic resin (A) and the copolymer (B) of an olefin and a functional group-containing monomer is preferably 50% by mass or more and 80% by mass or less based on the mass of the entire thermoplastic resin molded body 1. When the total blending ratio of the polyolefin-based thermoplastic resin (A) and the copolymer (B) of an olefin and a functional group-containing monomer is 50% by mass or more, by suppressing an increase in the blending ratio of the ethylene-vinyl alcohol copolymer (C), a decrease in heat sealability can be prevented, high flexibility can be ensured, and impact resistance can be improved. Further, when the total blending ratio of the polyolefin-based thermoplastic resin (A) and the copolymer (B) of an olefin and a functional group-containing monomer is 80% by mass or less, a sufficient blending amount of the ethylene-vinyl alcohol copolymer (C) can be ensured, and barrier properties can be improved.

[0024] Also, the blending ratio of the copolymer (B) of an olefin and a functional group-containing monomer in the thermoplastic resin molded body 1, that is, the content of the copolymer (B) of an olefin and a functional group-containing monomer is preferably 0.5% by mass or more and 10% by mass or less based on the mass of the entire thermoplastic resin molded body 1. When the blending ratio of the copolymer (B) of an olefin and a functional group-containing monomer is 0.5% by mass or more, a decrease in the interfacial energy between the polyolefin-based thermoplastic resin (A) and the ethylene-vinyl alcohol copolymer (C) is prevented, and the occurrence of delamination between the polyolefin-based thermoplastic resin (A) and the ethylene-vinyl alcohol copolymer (C) is suppressed, and barrier properties can be improved. When the blending ratio of the copolymer (B) of an olefin and a functional group-containing monomer is 10% by mass or less, a decrease in the dispersion size of (C) is prevented, and by obtaining barrier properties due to the tortuosity effect, oxygen barrier properties are improved.

[0025] 〈Ethylene-vinyl alcohol copolymer〉 Ethylene-vinyl alcohol copolymer (EVOH) (C) can be produced by saponifying ethylene-vinyl acetate copolymer (EVA) obtained by radical polymerization of ethylene and vinyl acetate. The oxygen barrier property of ethylene-vinyl alcohol copolymer (EVOH) is improved by a lower ethylene content, or a higher degree of hydrolysis or saponification, and higher crystallinity. It is preferable to use an ethylene-vinyl alcohol copolymer having an ethylene component ratio of 20 to 50 mol% and a degree of hydrolysis of 90% or more.

[0026] The blending ratio of ethylene-vinyl alcohol copolymer (C) is preferably in the range of 20% by mass or more and 50% by mass or less based on the mass of the entire thermoplastic resin molded body. If the blending ratio of ethylene-vinyl alcohol copolymer (C) is 50% by mass or less, the dispersed phase can be formed as islands in the continuous phase. Also, by making the mass ratio smaller than that of the polyolefin-based thermoplastic resin (A) which is the main phase, inversion of sea and islands can be prevented, and impact resistance can be ensured without impairing the flexibility as a packaging material. Furthermore, if the blending ratio of ethylene-vinyl alcohol copolymer (C) is 50% by mass or less, an increase in the ratio of ethylene-vinyl alcohol copolymer appearing on the surface of the packaging material can be prevented, and high heat sealability can be ensured when used as a packaging film material. If the blending ratio of ethylene-vinyl alcohol copolymer (C) is 20% by mass or more, the barrier property obtained by the maze effect can be improved by preventing a decrease in the abundance ratio of ethylene-vinyl alcohol copolymer (C).

[0027] The ethylene-vinyl alcohol copolymer (C) in the core-shell structure of the dispersed phase 2 has a cross-sectional area of 4 μm 2 or more and 400 μm 2 or less in the cross-section of the thick portion in the molding direction Dm of the thermoplastic resin molded body 1 as shown in FIG. 2. Similarly, the ethylene-vinyl alcohol copolymer (C) has a cross-sectional area of 4 μm 2 or more and 400 μm 2It is within the following range. When the cross-sectional area of the ethylene-vinyl alcohol copolymer (C) is 4 μm 2 or more, a high barrier property can be obtained due to the maze effect. When the cross-sectional area of the ethylene-vinyl alcohol copolymer (C) is 400 μm 2 or less, the flexibility as a packaging material can be maintained without impairment, and the impact resistance can be ensured.

[0028] Also, as shown in FIG. 1, when the major axis length of the ethylene-vinyl alcohol copolymer (C) is d1 and the minor axis length is d2, the aspect ratio in the forming direction Dm of the ethylene-vinyl alcohol copolymer (C), that is, the ratio of the major axis length d1 to the minor axis length d2 of the ethylene-vinyl alcohol copolymer (C) is within the range of 15 or more and 100 or less, and the aspect ratio in the forming width direction Dw is within the range of 15 or more and 100 or less. If the aspect ratios of the ethylene-vinyl alcohol copolymer (C) in the forming direction Dm and the forming width direction Dw are within the range of 15 or more and 100 or less, it is advantageous for the formation of the maze structure and the barrier property is improved.

[0029] (Method for manufacturing a thermoplastic resin molded body) The method for producing the thermoplastic resin molded body of the present embodiment is not particularly limited, and a known method can be used.

[0030] As the method for producing the molded body, an injection molding machine, an extrusion molding machine, a method of forming a film with a T-die through a feed block or a multi-manifold, or a method of forming a film using an inflation method can be used. In the present embodiment, a film-forming method using an extrusion molding machine will be described.

[0031] In the present embodiment, the thermoplastic resin molded body 1 according to the present invention is produced by mixing and extruding the thermoplastic resin according to the present invention in an extrusion molding machine. The extrusion molding machine has a compression mechanism such as a breaker plate that promotes pressure increase to apply a load to the resin after the resin passes through the screw.

[0032] Regarding the method for cooling the film, it can be used according to the above-mentioned molding machine. For example, in the T-die method, there is no particular limitation, such as air-cooling methods like an air chamber, a vacuum chamber, an air knife, or a water-cooling method such as dipping a cooling roll into a cold water pan. However, when imparting a surface uneven shape by shaping, a method in which molten resin flows into a contact portion where a nip roll processed with silicone rubber, NBR rubber, or fluororesin, etc., and a cooling roll processed by cutting metal are applied with a pressure of 0.1 MPa or more and then cooled is particularly preferred.

[0033] In the film form of the thermoplastic resin molded body obtained by the present invention, it can be a single film or laminated with other base materials to form a packaging material. When used as a single film or a laminate, in addition to a standing pouch, it can be used for three-side sealed bags, gusseted bags, spout bags, pouches with beaks, etc. Also, the bag-making style of the packaging bag is not particularly limited.

[0034] As described above, in either case of a single film or lamination with other base materials, it is possible to appropriately perform a surface modification treatment to improve the suitability for subsequent processes. For example, it is possible to perform a surface modification treatment on the surface in contact with other base materials in order to improve the printing suitability when using a single film or the laminating suitability when using in lamination. The surface modification treatment can preferably use a method of expressing functional groups by oxidizing the film surface such as corona discharge treatment, plasma treatment, flame treatment, etc., or modification by a wet process such as coating an easy-adhesion layer.

[0035] (Packaging material) The packaging material as one aspect of the present invention is formed using the above-mentioned thermoplastic resin molded body 1. By configuring in this way, the packaging material has the necessary oxygen barrier property, and a thermoplastic resin molded body having high impact resistance and heat sealability can be effectively utilized in the form of a packaging material.

[0036] <Effects of the present embodiment> The above-mentioned thermoplastic resin molded body 1 has the following effects. (1) The thermoplastic resin molded article 1 of the present disclosure contains a resin (A) having a water vapor barrier property, a resin (B) having a functional group, and a resin (C) having an oxygen barrier property. Thereby, the thermoplastic resin molded article 1 can achieve both a water vapor barrier property and an oxygen barrier property.

[0037] (2) The resin (B) having a functional group of the present disclosure is a resin different from the resin (A) having a water vapor barrier property, and the functional group has a reactive group that can bind to the resin (C) having an oxygen barrier property. Thereby, the thermoplastic resin molded article 1 can reduce the interfacial tension between the resin (A) having a water vapor barrier property and the resin (C) having an oxygen barrier property, and stabilize the phase separation structure.

[0038] (3) In the thermoplastic resin molded article 1 of the present disclosure, a core-shell structure in which the resin (B) having a functional group encloses the resin (C) having an oxygen barrier property forms a dispersed phase that exists as islands in the resin (A) having a water vapor barrier property. Thereby, the thermoplastic resin molded article 1 can optimize the maze effect that is effective for oxygen barrier.

Examples

[0039] Hereinafter, examples of the present invention will be described in detail, but the present invention is not limited only to the following examples.

[0040] (Example 1) As the resin used for the polyolefin-based thermoplastic resin (A), the homopolypropylene resin F-300SP manufactured by Prime Polymer Co., Ltd. was used. Also, as the copolymer (B) of an olefin and a functional group-containing monomer, Admer QE060 of maleic anhydride-modified polypropylene manufactured by Mitsui Chemicals, Inc. was used. And as the ethylene-vinyl alcohol copolymer (C), the EVOH resin Soarnol D2908 (ethylene ratio 29 mol%) manufactured by Mitsubishi Chemical Corporation was used. The mixing ratios (mass %) of the polyolefin-based thermoplastic resin (A), the copolymer (B) of an olefin and a functional group-containing monomer, and the ethylene-vinyl alcohol copolymer (C) were adjusted to (A):(B):(C) = 49.5:0.5:50, dry-blended, and fed into a single-screw extruder. The flow path was set so as to pass through a compression section with a compression ratio of 65% after the screw section, and a film with a thickness of 100 μm was formed by the T-die casting method at a molding temperature of 250°C. Thus, the film of Example 1 was formed.

[0041] (Example 2) The film of Example 2 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 40:10:50.

[0042] (Example 3) The film of Example 3 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 79.5:0.5:20.

[0043] (Example 4) The film of Example 4 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 70:10:20.

[0044] (Example 5) The film of Example 5 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 45:5:50.

[0045] (Example 6) The film of Example 6 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 75:5:20.

[0046] (Example 7) The film of Example 7 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 62:20:18.

[0047] (Example 8) The film of Example 8 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 60:20:20.

[0048] (Example 9) The film of Example 9 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 72:10:18.

[0049] (Example 10) The film of Example 10 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 49.7:0.3:50.

[0050] (Example 11) The film of Example 11 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 79.7:0.3:20.

[0051] (Example 12) The film of Example 12 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 39:11:50.

[0052] (Example 13) The film of Example 13 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 69:11:20.

[0053] (Example 14) A film of Example 14 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 84.5:0.5:15.

[0054] (Comparative Example 1) A film of Comparative Example 1 was formed in the same manner as in Example 1, except that the copolymer (B) of an olefin and a functional group-containing monomer was not used and the mixing ratio was adjusted to (A):(C) = 50:50.

[0055] (Comparative Example 2) A film of Comparative Example 2 was formed in the same manner as in Example 1, except that the copolymer (B) of an olefin and a functional group-containing monomer was not used and the mixing ratio was adjusted to (A):(C) = 80:20.

[0056] (Comparative Example 3) A film of Comparative Example 3 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C) = 44.5:0.5:55.

[0057] (Comparative Example 4) A film of Comparative Example 4 was formed in the same manner as in Example 1, except that the copolymer (B) of an olefin and a functional group-containing monomer and the ethylene-vinyl alcohol copolymer (C) were not used and only the polyolefin-based thermoplastic resin (A) was used.

[0058] (Evaluation) The following evaluations were performed on the films obtained in Examples 1 to 14 and Comparative Examples 1 to 4 described above.

[0059] [Measurement of the dispersion shape of the mass ratio of the ethylene-vinyl alcohol copolymer (C)] The major axis length, minor axis length, and aspect ratio of the ethylene-vinyl alcohol copolymer (C) were measured. The shape of the dispersed phase was observed using a scanning electron microscope (SEM) S-4800 manufactured by Hitachi High-Technologies. After obtaining an image at a magnification of 1000 times, the average values of the major axis dispersion diameter (major axis length) and minor axis dispersion diameter (minor axis length) of 20 randomly selected dispersed phases in the image were calculated. Also, the ratio of the measured major axis length to the minor axis length (major axis length / minor axis length) was defined as the aspect ratio.

[0060] Next, the cross-sectional area of the ethylene-vinyl alcohol copolymer (C) was measured. For the cross-sectional observation of the ethylene-vinyl alcohol copolymer (C) in the molding direction and the molding width direction, the films of the examples and comparative examples were cut out to a size of 2 mm × 5 mm (the observation part being 2 mm), and those embedded with a visible light curable embedding resin D-800 manufactured by JEOL Ltd. were cross-sectioned using a glass knife and a diamond knife with an ultramicrotome EM UC7i manufactured by Leica Microsystems. The cutting positions of the observation test pieces were randomly selected at 10 positions each in both the molding direction and the molding width direction of each film. For the observation, a scanning electron microscope (SEM) S-4800 manufactured by Hitachi High-Technologies was used. After obtaining 3000-fold observation images and 100,000-fold observation images, the cross-sectional areas of 20 randomly selected dispersed phases in the images were measured.

[0061] 〔Oxygen barrier property evaluation〕 The films obtained in the examples and comparative examples were cut to A4 size, and the oxygen permeability (cc / m 2 / day / atm) as a ratio to that of pure polypropylene under dry conditions at 30°C was measured using a high-sensitivity water vapor permeability measuring device GTR-3000 manufactured by GTR Tech Co., Ltd. The measured oxygen permeability was evaluated in the following three grades: ◎, 〇, and △. <Evaluation criteria> ◎: When the oxygen permeability is 0.02 (1 / 50) or less. 〇: When the oxygen permeability is 0.05 (1 / 20) or less. △: When the oxygen permeability is in the range of 0.1 or more and less than 0.6.

[0062] [Impact Resistance Performance Evaluation] In the impact resistance performance evaluation, a drop bag evaluation was carried out. The implementation details of the drop bag evaluation are described below. PET with a thickness of 12 μm (PTMB-12 manufactured by Unitika Ltd.), ONy with a thickness of 15 μm (ON#15 manufactured by Unitika Ltd.), and the films obtained in the examples and comparative examples were laminated, and dry lamination was performed to prepare samples with a three-layer structure. In addition, samples were prepared by laminating using an adhesive (A626 / A-50, main agent or curing agent manufactured by Mitsui Chemicals, Inc.). These samples were cut to prepare two samples with an outer dimension of 130 × 200 mm and an inner dimension of 90 × 160 mm. The two samples were overlapped, and one side at the longitudinal end and two sides at the transverse ends were heat-sealed with a heat sealer at 200 °C, 0.15 MPa, and for 1 second over a width of 5 mm to prepare a pouch with one side at the longitudinal end open. Next, 150 ml of water at 5 °C was filled as the content from the open part of the pouch. Then, the open part was heat-sealed with a heat sealer at 200 °C, 0.15 MPa, and for 1 second over a width of 5 mm to seal the pouch.

[0063] After the sealed pouch was put into a high-temperature and high-pressure cooking sterilization device, high-temperature steam retort treatment was performed, and the pouch after the retort treatment was stored in the refrigerator. Then, the pouch was taken out from the refrigerator and horizontally dropped from a height of 150 cm. The number of drops was 30 times, and the number of pouches to be horizontally dropped was 20 bags. After 30 horizontal drops, the presence or absence of bag breakage was visually confirmed for each of the 20 pouches. The drop bag strength was evaluated in the following three levels: ◎, ○, ×. [Evaluation Criteria] ◎: When the non-broken bag rate (the ratio of non-broken pouches) is 70% or more of the total ○: When the non-broken bag rate is more than 60% and less than 70% of the total ×: When the non-broken bag rate is less than 60% of the total

[0064] [Heat Sealability Evaluation] The heat sealability evaluation was carried out as follows: Using a heat sealer (model number TP-701-B) manufactured by Tester Sangyo Co., Ltd., with a seal pressure of 0.2 MPa, a seal time of 1 second, a seal width of 10 mm, and a seal temperature of 180°C, the front or back surfaces of the films obtained in the examples and comparative examples were overlapped and sealed. The sealed film was cut into pieces with a width of 15 mm and a length of 100 mm. Using a tensile testing machine (model number AGS-500NX) manufactured by Shimadzu Corporation, with a distance between chucks of 50 mm and a tensile speed of 300 mm / min, the seal strength was measured when subjected to 180° T-peel. The measured seal strength was evaluated in the following three grades: ○, △, and ×. <Evaluation Criteria> ○: When the seal strength is 10.0 N or more △: When the seal strength is 9.0 N or more ×: When the seal strength is less than 9.0 N

[0065] (Evaluation Results) The following Table 1 shows the compositions of the films of each example and comparative example. Also, the following Table 2 shows the evaluation results of the oxygen barrier property, impact resistance performance, and heat sealability of each example and comparative example.

[0066] [Table 1]

[0067] [Table 2]

[0068] As shown in Tables 1 and 2, from the evaluation results of Examples 1 to 14 and Comparative Examples 1 and 2, when a copolymer (B) of an olefin and a functional group-containing monomer is included as in Examples 1 to 14, compared with the case where a copolymer (B) of an olefin and a functional group-containing monomer is not included as in Comparative Examples 1 and 2, it was found that the copolymer (B) of an olefin and a functional group-containing monomer plays a role in compatibilizing the matrix phase and the dispersed phase, and thus has a high oxygen barrier property.

[0069] Furthermore, from the evaluation results of Examples 1 to 14 and Comparative Example 3, when the polyolefin-based thermoplastic resin (A) exists as the continuous phase and the ethylene-vinyl alcohol copolymer (C) exists as the dispersed phase as in Examples 1 to 14, the impact resistance and heat sealability are higher than those in the case where the polyolefin-based thermoplastic resin (A) is the continuous phase and the ethylene-vinyl alcohol copolymer (C) changes to the dispersed phase as in Comparative Example 3.

[0070] Also, from the evaluation results of Examples 1 to 14 and Comparative Example 4, when the ethylene-vinyl alcohol copolymer (C) is included as in Examples 1 to 14, the oxygen barrier property is higher than that in the case where the ethylene-vinyl alcohol copolymer (C) is not included as in Comparative Examples 1 and 2.

[0071] Moreover, from the evaluation results of Examples 1 to 9, 12 to 14 and Examples 10 and 11, when the copolymer (B) of an olefin and a functional group-containing monomer is contained at 0.5% by mass or more as in Examples 1 to 9, 12 to 14, the occurrence of delamination is prevented and the impact resistance performance is higher than that in the case where the copolymer (B) of an olefin and a functional group-containing monomer is not contained at 0.5% by mass or more as in Examples 10 and 11.

[0072] Also, from the evaluation results of Examples 1 to 11, 14 and Examples 12 and 13, when the copolymer (B) of an olefin and a functional group-containing monomer is contained at 10% by mass or less as in Examples 1 to 11, 14, the aspect ratio of the dispersed phase does not become too small by preventing the fine dispersion of the dispersed phase, and a high oxygen barrier property is provided as compared with the case where the copolymer (B) of an olefin and a functional group-containing monomer is not contained at 10% by mass or more as in Examples 12 and 13.

[0073] Note that the thermoplastic resin molded body and the packaging material using the thermoplastic resin molded body of the present disclosure are not limited to the above-described embodiments and examples, and various modifications are possible without impairing the features of the invention.

Explanation of Reference Numerals

[0074] 1: Thermoplastic resin molded body 2: Dispersed phase (copolymer (B) of olefin and functional group-containing monomer and ethylene-vinyl alcohol copolymer (C)) 3: Continuous phase (polyolefin-based thermoplastic resin (A)) 4: Copolymer (B) of olefin and functional group-containing monomer 5: Ethylene-vinyl alcohol copolymer (C)

Claims

1. comprising a resin having a water vapor barrier property, a resin having a functional group, and a resin having an oxygen barrier property, the resin having the functional group is a resin different from the resin having the water vapor barrier property, and the functional group has a reactive group capable of bonding to the resin having the oxygen barrier property, a core-shell structure in which the resin having the functional group encapsulates the resin having the oxygen barrier property forms a dispersed phase present as islands in the resin having the water vapor barrier property, the resin having the water vapor barrier property includes a polyolefin-based thermoplastic resin, the resin having the oxygen barrier property includes an ethylene-vinyl alcohol copolymer, the resin having the functional group includes a copolymer of an olefin and a functional group-containing monomer, the functional group-containing monomer has a hydroxyl group or a carbonyl group as the functional group, The resin having oxygen barrier properties in the core-shell structure has an average cross-sectional area of the resin having oxygen barrier properties per core-shell structure in each of the molding direction and the molding width direction of 4 μm ２ 400 μm or more ２ The aspect ratio in the molding direction is within the range of 15 to 100, and the aspect ratio in the molding width direction is within the range of 15 to 100.

2. comprising a resin having a water vapor barrier property, a resin having a functional group, and a resin having an oxygen barrier property, the resin having the functional group is a resin different from the resin having the water vapor barrier property, and the functional group has a reactive group capable of bonding to the resin having the oxygen barrier property, a core-shell structure in which the resin having the functional group encapsulates the resin having the oxygen barrier property forms a dispersed phase present as islands in the resin having the water vapor barrier property, the resin having the water vapor barrier property includes a polyolefin-based thermoplastic resin, the resin having the oxygen barrier property includes an ethylene-vinyl alcohol copolymer, the resin having the functional group is an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-butyl acrylate copolymer, an ethylene-vinyl alcohol copolymer, an ethylene-methacrylic acid copolymer, an ethylene-methyl methacrylate copolymer, or a maleic acid-modified polyolefin, The resin having oxygen barrier properties in the core-shell structure has an average value of the cross-sectional area of the resin having oxygen barrier properties per core-shell structure in each of the molding direction and the molding width direction of 4 μm ２ or more and 400 μm ２ or less, a thermoplastic resin molded body having an aspect ratio in the molding direction in the range of 15 or more and 100 or less, and an aspect ratio in the molding width direction in the range of 15 or more and 100 or less.

3. comprising a resin having a water vapor barrier property, a resin having a functional group, and a resin having an oxygen barrier property, the resin having the functional group is a resin different from the resin having the water vapor barrier property, and the functional group has a reactive group capable of bonding to the resin having the oxygen barrier property, a core-shell structure in which the resin having the functional group encapsulates the resin having the oxygen barrier property forms a dispersed phase present as islands in the resin having the water vapor barrier property, the resin having the water vapor barrier property includes a polyolefin-based thermoplastic resin, The resin having oxygen barrier properties includes an ethylene-vinyl alcohol copolymer, The resin having the functional group is maleic anhydride-modified polypropylene, The resin having oxygen barrier properties in the core-shell structure has an average value of the cross-sectional area of the resin having oxygen barrier properties per core-shell structure in each of the molding direction and the molding width direction of 4 μm ２ or more and 400 μm ２ or less, a thermoplastic resin molded body having an aspect ratio in the molding direction in the range of 15 or more and 100 or less, and an aspect ratio in the molding width direction in the range of 15 or more and 100 or less.

4. The resin having oxygen barrier properties in the core-shell structure is within the range of 4 μm2 or more and 400 μm2 or less of the average value of the cross-sectional area of the resin having oxygen barrier properties per core-shell structure calculated for 20 randomly selected out of the core-shell structures observed in a 2 mm × 2 mm cross-sectional observation region in each of the molding direction and the molding width direction. The thermoplastic resin molded article according to any one of Claims 1 to 3, characterized in that

5. The mass ratio of the resin having oxygen barrier properties is in the range of 20% by mass or more and 50% by mass or less with respect to the mass of the entire thermoplastic resin molded article. The thermoplastic resin molded article according to any one of Claims 1 to 4, characterized in that

6. The blending ratio of the resin having water vapor barrier properties is 40% by mass or more and 79.5% by mass or less with respect to the mass of the entire thermoplastic resin molded article, The blending ratio of the resin having the functional group is 0.5% by mass or more and 10% by mass or less with respect to the mass of the entire thermoplastic resin molded article, The total blending ratio of the resin having water vapor barrier properties and the resin having the functional group is 50% by mass or more and 80% by mass or less with respect to the mass of the entire thermoplastic resin molded article. The thermoplastic resin molded article according to any one of Claims 1 to 5, characterized in that

7. A packaging material characterized by using the thermoplastic resin molded article according to any one of Claims 1 to 6.

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