Thermoplastic resin moldings and packaging materials

Abstract

To provide a thermoplastic resin molded body which has an oxygen barrier property by controlling a dispersion state of an ethylene-vinyl alcohol copolymer having an oxygen barrier property, and which also has heat-sealability, and to provide a packaging material.SOLUTION: A thermoplastic resin molded body includes resin having a steam barrier property and resin having an oxygen barrier property, and the resin having the oxygen barrier property is present as islands in the resin having the steam barrier property and forms dispersion phases. In the dispersion phases, the sizes of the distributed dispersion phases are different by the depth in the thickness direction of the thermoplastic resin molded body. In the cross section in parallel in the molding direction and the thickness direction of the thermoplastic resin molded body in the surface and rear surface regions, the average value of the cross section areas of the dispersion phases is equal to or greater than 0.05 μm2 and equal to or less than 0.8 μm2, and in the cross section in parallel in the molding width direction and the thickness direction of the thermoplastic resin molded body in the intermediate region, the average value of the cross section areas of the dispersion phrases is equal to or greater than 1 μm2 and equal to or less than 400 μm2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Packaging materials (packaging films, packages, and containers) use various resin films and molded resins with excellent gas barrier properties to protect the contents. Materials commonly used for packaging are primarily composed of olefin-based resins such as polyethylene (hereinafter "PE") and polypropylene (hereinafter "PP"). These olefin-based resins have excellent barrier properties against water vapor, but poor 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 poor barrier properties against water vapor.

[0003] One of the properties required for packaging materials is heat sealing property, and in order to generally obtain heat sealing property, the resin of the surface layer must be a resin that does not impede heat sealing property.

[0004] The barrier properties required for packaging materials include both oxygen barrier properties and water vapor barrier properties, but conventionally, barrier properties that combine oxygen and water vapor have been achieved by laminating multiple resins with oxygen barrier properties and multiple resins with water vapor barrier properties. Furthermore, the properties required for packaging materials have been achieved by placing a layer specialized for heat sealing properties on the surface. Patent Document 1 discloses a technology that achieves both barrier properties and heat sealing properties through lamination. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-080984 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-150539 Summary of the Invention [Problem to be solved by the invention]

[0006] Furthermore, Patent Document 2 discloses a technology that provides excellent impact resistance and high barrier properties by using a polyolefin resin such as PE or PP for the surface layer, and EVOH or MXD nylon for the middle layer, combined with an acid-modified or other compatibilizer as a composite material. However, when achieving both barrier properties and heat sealability by lamination, there are problems such as a decrease in adhesiveness between the individual laminated films and a complicated manufacturing process. Furthermore, when a material having oxygen barrier properties and a material having water vapor barrier properties are mixed together in order to obtain oxygen barrier properties, there is a problem that sufficient oxygen barrier properties cannot be obtained by simply melt blending the materials together, and the material having oxygen barrier properties inhibits heat sealing properties.

[0007] The present invention has been made in consideration of the above problems, and aims to provide a thermoplastic resin molded article that has excellent oxygen barrier properties and does not impair the heat sealability required for packaging, by dispersing a material with excellent oxygen barrier properties in a material with excellent water vapor barrier properties and controlling the dispersion state of the oxygen barrier resin, which is the dispersed phase, in the thickness direction of the molded article, and to provide a packaging material using the same. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, a thermoplastic resin molded product according to one aspect of the present disclosure and a packaging material using the same comprise a resin having water vapor barrier properties and a resin having oxygen barrier properties, and the resin having oxygen barrier properties is present as islands in the resin having water vapor barrier properties to form a dispersed phase, and the size of the dispersed phase distributed depending on the depth in the thickness direction of the thermoplastic resin molded product varies, and in cross sections parallel to the molding direction and thickness direction of the thermoplastic resin molded product in the front and back regions, the average value of the cross-sectional area of ​​the dispersed phase is 0.05 μm 2 More than 0.80μm 2or less, and the average cross-sectional area of ​​the dispersed phase in a cross section parallel to the molding width direction and thickness direction of the thermoplastic resin molded body in the intermediate region is 1.00 μm 2 More than 400μm 2 The gist is as follows. [Effects of the Invention]

[0009] With the thermoplastic resin molded article according to one embodiment of the present disclosure and the packaging material using the same, it is possible to provide a thermoplastic resin molded article and a packaging material using the same that have the oxygen barrier property and heat sealability required for packaging materials by controlling the dispersion state in the thickness direction of the ethylene-vinyl alcohol copolymer that has oxygen barrier property. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating an example of a configuration of a thermoplastic resin molded body according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view schematically illustrating one configuration example of a thermoplastic resin molded body according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present disclosure will be described with reference to the drawings. The present invention will be described in detail below. Note that the configurations shown in the drawings are schematic, and the size and shape of each part are appropriately exaggerated to facilitate understanding. Furthermore, the embodiments shown below are examples of configurations that embody the technical idea of ​​the present invention, and the technical idea of ​​the present invention is not limited to the materials, shapes, structures, etc. of the components described below. The technical idea of ​​the present invention can be variously modified within the technical scope defined by the claims.

[0012] (Configuration of thermoplastic resin molded body) The basic configuration of a thermoplastic resin molded body according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram for explaining one example of the configuration of a thermoplastic resin molded body 1 according to this embodiment. The thermoplastic resin molded product 1 contains a resin having water vapor barrier properties, a resin having functional groups, and a resin having oxygen barrier properties. In particular, the thermoplastic resin molded product 1 in this embodiment includes a polyolefin-based thermoplastic resin (A) having water vapor barrier properties, a copolymer (C) of an olefin and a functional group-containing monomer, and an ethylene-vinyl alcohol copolymer (B) having oxygen barrier properties. As shown in Figure 1, the thermoplastic resin molded product 1 has a core-shell structure in which the copolymer (C) 4 of an olefin and a functional group-containing monomer encases the ethylene-vinyl alcohol copolymer (B) 5, forming a dispersed phase 2 that exists as islands in a continuous phase 3 containing the polyolefin-based thermoplastic resin (A).

[0013] In addition to the polyolefin-based thermoplastic resin (A), the copolymer of an olefin and a functional group-containing monomer (C), and the ethylene-vinyl alcohol copolymer (B), additives such as a nucleating agent and a reinforcing filler may be used in the thermoplastic resin molded body 1. Examples of nucleating agents and reinforcing fillers include talc, silica, clay, montmorillonite, calcium carbonate, lithium alumina carbonate, titanium oxide, metals such as aluminum, iron, silver, and copper, hydroxides such as aluminum hydroxide and magnesium hydroxide, celluloses such as cellulose microfibrils and cellulose acetate, fibrous fillers such as glass fibers, polyethylene terephthalate fibers, nylon fibers, polyethylene naphthalate fibers, aramid fibers, vinylon fibers, and polyacrylate fibers, and carbons such as carbon nanotubes. These may be used alone or in combination of two or more.

[0014] The thermoplastic resin molded body 1 may also contain additives such as antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, flame retardants, and flame retardant aids. Examples of antioxidants include phenolic compounds, organic phosphite compounds, and thioether compounds. Examples of heat stabilizers include hindered amine compounds. Examples of ultraviolet absorbers include benzophenone compounds, benzotriazole compounds, and benzoate compounds. Examples of antistatic agents include nonionic compounds, cationic compounds, and anionic compounds. Examples of flame retardants include halogen compounds, phosphorus compounds, nitrogen compounds, inorganic compounds, boron compounds, silicone compounds, sulfur compounds, and red phosphorus compounds. Examples of flame retardant aids include antimony compounds, zinc compounds, bismuth compounds, magnesium hydroxide, and clay silicates. These compounds may be used alone or in combination.

[0015] Other additives such as weathering agents, light stabilizers, plasticizers, slip agents, antiblocking agents, antifogging agents, lubricants, pigments, dyes, dispersants, copper inhibitors, neutralizing agents, bubble inhibitors, weld strength improvers, natural oils, synthetic oils, waxes, etc. may be used in the thermoplastic resin molded body 1. These may be used alone or in combination of two or more.

[0016] The thermoplastic resin molded body 1 may be used not only as a single layer, but also as a laminate with other types of resin molded bodies.

[0017] (continuous phase) The continuous phase 3 is composed of a resin having water vapor barrier properties. As the thermoplastic resin molded body 1 is formed into a film using an extrusion molding machine capable of heating up to 340°C, any common thermoplastic resin can be used as the main material of the continuous phase 3, but in order to be suitable for use as a packaging material, it is necessary for the resin to have appropriate flexibility and good processability. In this embodiment, the main material of the continuous phase 3 is a polyolefin-based thermoplastic resin (A) having excellent water vapor barrier properties.

[0018] <Polyolefin-based thermoplastic resin> The polyolefin-based thermoplastic resin (A) may be any polymer having a structural unit derived from an olefin, and may be selected from olefin-based low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE) obtained by copolymerizing 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 cycloolefin and olefin, ethylene-vinyl acetate copolymer obtained by copolymerizing the above-mentioned olefin with 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 olefin, and may be used singly or in combination as appropriate.

[0019] The blending ratio of the polyolefin-based thermoplastic resin (A) is preferably 40% by mass or more and 85% by mass or less relative to the total mass of the thermoplastic resin molded body 1. When the polyolefin-based thermoplastic resin (A) is 40% by mass, it is even more preferable that the total of the copolymer (C) of an olefin and a functional group-containing monomer is 50% by mass. When the blending ratio of the polyolefin-based thermoplastic resin (A) is 85% by mass or less, the blending amount of the ethylene-vinyl alcohol copolymer (B) can be sufficiently ensured, thereby improving the barrier property. When the blending ratio of the ethylene-vinyl alcohol copolymer (B) is 50% by mass or more, the sea and islands of the so-called sea-island structure are reversed. In other words, EVOH becomes a continuous phase and easily absorbs water vapor. Generally, EVOH that has absorbed water vapor has reduced oxygen barrier property, so this sea-island inversion phenomenon must be avoided.

[0020] (dispersed phase) As shown in Figure 1, the dispersed phase 2 is present so as to be dispersed in the continuous phase 3. The islands of the dispersed phase are divided into at least three regions in the thermoplastic resin molded article: a front region, a back region, and an intermediate region. The dispersed phase islands have an average size of 0.05 μm in the front and back regions.2 or more, 0.80μm 2 Below, the average size of the dispersed phase in the intermediate region is 1.00 μm 2 More than 400μm 2 The thickness of the front and back regions is 5 μm or more and 20 μm or less, and the thickness of the intermediate region is 20 μm or more. The dispersed phase 2 also contains a resin having oxygen barrier properties and a resin having functional groups. In this embodiment, the dispersed phase 2 may have a core-shell structure containing a simple ethylene-vinyl alcohol copolymer (B) having excellent oxygen barrier properties and a copolymer (C) of an olefin and a functional group-containing monomer. As shown in Figure 1, the dispersed phase 2 may have a core-shell structure in which the copolymer (B) of an olefin and a functional group-containing monomer encases the ethylene-vinyl alcohol copolymer (C), or a structure consisting of only a core.

[0021] <Copolymer of olefin and functional group-containing monomer> In this embodiment, a copolymer (C) of an olefin and a functional group-containing monomer is used as the resin having a functional group. The copolymer (C) of an olefin and a functional group-containing monomer forms an immiscible material between the polyolefin thermoplastic resin (A) and the ethylene-vinyl alcohol copolymer (B) described below, thereby reducing the interfacial tension between the two polymers during mixing and stabilizing the phase-separated structure. The copolymer (C) of an olefin and a functional group-containing monomer is a resin different from the polyolefin thermoplastic resin (A) constituting the continuous phase 3. It is a copolymer thermoplastic resin with a molecular structure that has reactive groups capable of bonding with the ethylene-vinyl alcohol copolymer (B), and functions as a compatibilizer that improves the affinity between the olefin resin and the ethylene-vinyl alcohol copolymer, which have poor chemical compatibility. Examples of thermoplastic resins that function as compatibilizers include ethylene-vinyl acetate copolymer (EVA), 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), and maleic acid-modified polyolefin (hereinafter referred to as "PO-g-MAH"). While the present embodiment uses a copolymer (C) of an olefin and a functional group-containing monomer as the resin having a functional group, this is not limiting. For example, resins having hydroxyl groups, carbonyl groups, or the like can be used as the resin having a functional group.

[0022] The blending ratio of the copolymer (C) of an olefin and a functional group-containing monomer in the thermoplastic resin molded body 1, i.e., the content of the copolymer (C) of an olefin and a functional group-containing monomer, is preferably 0.5% by mass or more and 10% by mass or less relative to the total mass of the 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, it is present between the polyolefin thermoplastic resin (A) and the ethylene-vinyl alcohol copolymer (B), reducing the interfacial tension with the polyolefin thermoplastic resin (A), suppressing delamination between the polyolefin thermoplastic resin (A) and the ethylene-vinyl alcohol copolymer (B), and improving the barrier property. When the blending ratio of the copolymer (C) of an olefin and a functional group-containing monomer is 10% by mass or less, the dispersion size of (B) is prevented from becoming small, and the barrier property is achieved through the maze effect, thereby improving the oxygen barrier property.

[0023] <Ethylene-vinyl alcohol copolymer> Ethylene-vinyl alcohol copolymer (EVOH) (B) can be produced by saponifying ethylene-vinyl acetate copolymer (EVA) obtained by radical polymerization of ethylene and vinyl acetate, etc. The oxygen barrier properties of ethylene-vinyl alcohol copolymer (EVOH) are improved by a lower ethylene content, a higher degree of hydrolysis or saponification, and high crystallinity, and it is preferable to use an ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 50 mol% and a degree of hydrolysis of 90% or more.

[0024] In this embodiment, an ethylene-vinyl alcohol copolymer (B) is used as the resin having oxygen barrier properties. The blending ratio of the ethylene-vinyl alcohol copolymer (B) is preferably in the range of 15% by mass or more and 50% by mass or less with respect to the total mass of the thermoplastic resin molded body. If the blending ratio of the ethylene-vinyl alcohol copolymer (B) is 50% by mass or less, a dispersed phase can be formed as islands in the continuous phase. If the blending ratio is less than 15% by mass, the dispersed phases tend to overlap insufficiently, which may result in insufficient barrier properties due to the maze effect. In this embodiment, the resin having oxygen barrier properties is an ethylene-vinyl alcohol copolymer (B), but is not limited to this. The mass proportion of the resin having oxygen barrier properties (B) is more preferably in the range of 15% by mass to 40% by mass relative to the total mass of the thermoplastic resin molded body.

[0025] The ethylene-vinyl alcohol copolymer (B) in the core-shell structure of the dispersed phase 2 has a cross-sectional area of ​​the thickness portion in the molding direction Dm of the thermoplastic resin molded body 1 as shown in FIG. 2, and the average size of the dispersed phase in the front and back regions is 0.05 μm. 2 or more, 0.80μm 2 Below, the average size of the dispersed phase in the intermediate region is 1.00 μm 2 More than 400μm 2 Similarly, in the cross section of the thickness portion in the molding width direction Dw, the cross-sectional area of ​​the dispersed phase in the front and back regions is 0.05 μm 2 or more, 0.80μm 2 Below, the average size of the dispersed phase in the intermediate region is 1.00 μm 2 More than 400μm 2 The cross-sectional area of ​​the ethylene-vinyl alcohol copolymer (B) in the front and back regions is within the range of 0.05 μm 2 If the thickness is 0.80 μm or more, a low barrier effect is imparted to the front and back regions. 2 In the following cases, heat seal strength that does not impair heat sealability can be obtained: 2 When the cross-sectional area of ​​the ethylene-vinyl alcohol copolymer (B) is 400 μm or more, a high barrier property can be obtained due to the labyrinth effect. 2 If the area S of the dispersion unit is 1 to 400 μm, the dispersion is insufficient, and the number of dispersed phases decreases, which makes the distance between the dispersed phases very large, making it difficult to form an effective labyrinth structure. 2In the intermediate region, the aspect ratio of the dispersed phase in the molding direction is 15 to 100 (long axis length / short axis length), and the aspect ratio in the molding width direction is 15 to 100, so that a good labyrinth structure can be obtained.

[0026] The thickness of the front and back regions is within the range of 5 μm or more and 20 μm or less. If it is less than 5 μm, the heat sealability is impaired, and the heat seal strength required for the package is insufficient. If it is thicker than 20 μm, the oxygen barrier properties are impaired. Furthermore, if the thickness of the middle region is less than 20 μm, sufficient oxygen barrier properties cannot be obtained.

[0027] (Method for manufacturing thermoplastic resin molded body) The method for producing the thermoplastic resin molded body of this embodiment is not particularly limited, and any known method can be used.

[0028] The molded body can be produced using an injection molding machine, an extrusion molding machine, a film-forming method using a T-die via a feed block or a multi-manifold, or a film-forming method using an inflation method. In this embodiment, a film-shaped molding method using an extrusion molding machine will be described.

[0029] In this embodiment, the thermoplastic resin is mixed and extruded in an extrusion molding process to produce a thermoplastic resin molded body 1. The extruder has a compression mechanism such as a breaker plate that applies a load to the resin after it passes through the screw, thereby promoting pressure increase.

[0030] The film can be cooled in a manner similar to that of the molding machine described above. For example, in the T-die method, air cooling methods such as air chambers, vacuum chambers, and air knives, and water cooling methods such as dipping a cooling roll in a cold water pan are not particularly limited. However, when imparting a surface texture by shaping, a method in which molten resin is poured into the contact area between a nip roll made of silicone rubber, NBR rubber, fluororesin, or the like and a cooling roll made of machined metal, with a pressure of 0.1 MPa or more applied, and then cooled is particularly preferred.

[0031] The film form of the thermoplastic resin molded article obtained by this embodiment can be used as a packaging material either as a standalone film or laminated with other substrates. When used as a standalone film or a laminate, it can be used for stand-up pouches, as well as three-sided bags, two-handled bags, gusseted bags, pouches with spouts, pouches with beaks, etc. Furthermore, the manufacturing style of the packaging bag is not particularly limited.

[0032] As described above, in both the case of a single film and when laminated with another substrate, it is possible to carry out a surface modification treatment to improve suitability for subsequent processes. For example, it is possible to carry out a surface modification treatment on the surface that comes into contact with another substrate to improve printability when using a single film and lamination suitability when using a laminate. As the surface modification treatment, a method of expressing functional groups by oxidizing the film surface, such as corona discharge treatment, plasma treatment, or flame treatment, or modification by a wet process, such as coating an easy-adhesion layer, can be suitably used.

[0033] (packaging material) A packaging material according to one embodiment of the present invention is formed using the above-described thermoplastic resin molded product 1. By configuring it in this manner, the thermoplastic resin molded product has the oxygen barrier properties required for a packaging material, and also has high impact resistance and heat sealability, and can be effectively used in the form of a packaging material. [Example]

[0034] Examples of the present invention will be described in detail below, but the present invention is not limited to the following examples.

[0035] Example 1 The polyolefin thermoplastic resin (A) for both the front and back regions and the middle region was Prime Polymer Co., Ltd.'s homopolypropylene resin F-300SP. The ethylene-vinyl alcohol copolymer (B) for both the front and back regions was Mitsubishi Chemical Corporation's EVOH resin Soarnol D2908 (ethylene ratio 29 mol%). The copolymer (C) of olefin and functional group-containing monomers for the front and back regions was Mitsui Chemicals Inc.'s maleic anhydride-modified polypropylene Admer QE060. The copolymer (C) of olefin and functional group-containing monomers for the middle region was Mitsui Dow Polychemicals Inc.'s EVA resin Evaflex EV450. The materials for the front, back, and middle regions were polyolefin thermoplastic resin (A), copolymer of olefin and functional group-containing monomer (C), and ethylene-vinyl alcohol copolymer (B) in a mixture ratio (mass%) of (A):(B):(C) = 49.5:50:0.5. The mixture was dry-blended and fed into three single-screw extruders. The flow path was set so that the mixture passed through a compression section with a compression ratio of 65% after the screw section. The mixture was multilayered using a feedblock method to form a layer structure of front region / middle region / back region, with both the front and back regions being 5 μm thick. A 100 μm-thick film was then produced using a T-die casting method at a molding temperature of 250 °C.

[0036] Example 2 A film of Example 2 was formed in the same manner as in Example 1, except that the thickness of each of the front and back regions was 20 μm.

[0037] Example 3 A 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)=40:50:10.

[0038] Example 4 A film of Example 4 was formed in the same manner as in Example 3, except that the thickness of each of the front and back regions was 20 μm.

[0039] Example 5 A 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)=84.5:15:0.5.

[0040] Example 6 A 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)=75:15:10.

[0041] Example 7 The film of Example 7 was formed in the same manner as in Example 1, except that the thickness of the intermediate region was adjusted to 20 μm.

[0042] Example 8 The film of Example 8 was formed in the same manner as in Example 1, except that the thickness of each of the front and back regions was adjusted to 3 μm.

[0043] Example 9 The film of Example 9 was formed in the same manner as in Example 1, except that the thickness of each of the front and back regions was adjusted to 22 μm.

[0044] Example 10 Example 10 was formed in the same manner as Example 1, except that the thickness of the intermediate region was adjusted to be less than 20 μm.

[0045] (Comparative Example 1) A film of Comparative Example 1 was formed in the same manner as in Example 1, except that EVA resin Evaflex EV450 manufactured by Dow Mitsui Polychemicals Co., Ltd. was used as the copolymer (C) of olefin and functional group-containing monomer used in the layers of the front and back regions.

[0046] (Comparative Example 2) A film of Comparative Example 2 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C)=45:55:0.

[0047] (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)=90:10:0.

[0048] Comparative Example 4 A film of Comparative Example 4 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C)=100:0:0.

[0049] (Comparative Example 5) A film of Comparative Example 5 was formed in the same manner as in Example 1, except that the mixing ratio was adjusted to (A):(B):(C)=0:100:0.

[0050] (Comparative Example 6) A film of Comparative Example 6 was formed in the same manner as in Example 1, except that the resin composition of the front and back regions consisted solely of a polyolefin-based thermoplastic resin (A).

[0051] (Comparative Example 7) The film of Comparative Example 7 was formed in the same manner as in Example 1, except that the resin composition of the front and back regions consisted solely of the EVOH resin Soarnol D2908 (ethylene ratio 29 mol%) manufactured by Mitsubishi Chemical Corporation as the ethylene-vinyl alcohol copolymer (B).

[0052] (Comparative Example 8) The film of Comparative Example 8 was formed in the same manner as in Example 1, except that the compression ratio after the screws of the extruder corresponding to the front and back regions was adjusted to 80%.

[0053] (Comparative Example 9) The film of Comparative Example 9 was formed in the same manner as in Example 1, except that the compression ratio after the screw of the extruder corresponding to the intermediate region was adjusted to 60% and Admer QE060, a maleic anhydride-modified polypropylene manufactured by Mitsui Chemicals, Inc., was used as the copolymer (C) of olefin and functional group-containing monomer.

[0054] <evaluation> The films obtained in the above-mentioned Examples 1 to 10 and Comparative Examples 1 to 9 were evaluated as follows. [Cross-section measurement of ethylene-vinyl alcohol copolymer (B)] Next, the cross-sectional area of ​​the ethylene-vinyl alcohol copolymer (B) was measured. Cross-sectional observation of the ethylene-vinyl alcohol copolymer (B) in the molding direction and molding width direction was performed by cutting out films of the Examples and Comparative Examples to 2 mm x 5 mm (2 mm observation area), embedding them in visible light-curable embedding resin D-800 manufactured by JEOL Ltd., and then cross-sectioning them using a glass knife and a diamond knife on an ultramicrotome EM UC7i manufactured by Leica Microsystems. Ten randomly selected cutting locations were used for observation specimens in both the molding direction and molding width direction of each film. For observation, a scanning electron microscope (SEM) S-4800 manufactured by Hitachi High-Technologies was used to obtain 3,000x and 100,000x magnification images, and then measuring the cross-sectional areas of 20 randomly selected dispersed phases within the images. The aspect ratio was similarly measured for the major axis length, minor axis length, and aspect ratio of the cross sections of 20 randomly selected dispersed phases.

[0055] [Oxygen barrier evaluation] The films obtained in the examples and comparative examples were cut into A4 size pieces, and the oxygen permeability (cc / m) relative to the polypropylene alone was measured at 30°C in a dry environment using a highly sensitive water vapor permeability measuring device GTR-3000 manufactured by GTR Tech Co., Ltd. 2 The measured oxygen permeability was evaluated on the following three levels: ◎, ○, ×.

[0056] <Evaluation criteria> ◎: When oxygen permeability is 0.02 (1 / 50) or less. 〇: When oxygen permeability is 0.05 (1 / 20) or less. ×: When the oxygen permeability is greater than 0.05.

[0057] [Water vapor barrier properties] The films obtained in the examples and comparative examples were cut into A4 size pieces, and the water vapor permeability (g / m) relative to the polypropylene alone was measured using a highly sensitive water vapor permeability measuring device GTR-3000 manufactured by GTR Tech Co., Ltd. under an environment of 40°C and 90% RH. 2 The measured oxygen permeability was evaluated according to the following three levels: ◎, ◯, ×.

[0058] <Evaluation criteria> ◎: When the oxygen permeability is 0.7 or more. ○: When the oxygen permeability is 0.5 or more. ×: Oxygen permeability is in the range of less than 0.5.

[0059] [Heat sealability evaluation] The maximum stress value of the films obtained in the examples and comparative examples was taken as the heat seal strength, and the heat seal strength was evaluated on a two-level scale of ◯ and × as follows.

[0060] <Evaluation criteria> 〇: For heat seal strength of 10N or more. ×: Heat seal strength less than 10N.

[0061] (Evaluation results) Tables 1 to 4 show the evaluation results of the oxygen barrier property, water vapor barrier property, and heat sealability of each of the Examples and Comparative Examples.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] [Table 4]

[0066] In Examples 1 to 10, the films had oxygen barrier properties, water vapor barrier properties, and good heat sealability.

[0067] In Comparative Example 1, the dispersed phase size in the front and back regions was large and the aspect ratio was also high, which inhibited heat sealing properties and prevented the necessary heat sealing strength from being obtained.

[0068] In Comparative Example 2, the homopropylene resin forms a dispersed phase in both the front and back regions and the intermediate region, so that the water vapor barrier property is not obtained and the heat sealability is also impaired.

[0069] In Comparative Example 3, the dispersed phase size in the front and back regions becomes coarse, impairing heat sealability, and the absence of a compatibilizer in the intermediate region also causes peeling between the dispersed phase and the base phase, impairing oxygen barrier properties.

[0070] In Comparative Examples 4 and 5, a single resin phase was formed, and oxygen barrier property or hydrogen barrier property was not obtained. In particular, when an EVOH single layer was formed, heat sealability was also impaired.

[0071] In Comparative Examples 6 and 7, the resin in the front and back regions is a single material, so oxygen barrier properties or hydrogen barrier properties are not obtained.

[0072] In Comparative Example 8, the size of the dispersed phase is small in the front and back regions, the labyrinth effect is not obtained, and the oxygen barrier property is reduced.

[0073] In Comparative Example 9, the dispersed size of the intermediate region was small and the aspect ratio was also small, so that the labyrinth effect was not obtained and oxygen barrier properties were not obtained.

[0074] The thermoplastic resin molded body and 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 within the scope that does not impair the characteristics of the invention. [Explanation of symbols]

[0075] 1... Thermoplastic resin molded body 2. Dispersed phase (copolymer of olefin and functional group-containing monomer (C) and ethylene-vinyl alcohol copolymer (B)) 3. Continuous phase (polyolefin thermoplastic resin (A)) 4. Copolymer of olefin and functional group-containing monomer (C) 5. Ethylene-vinyl alcohol copolymer (B)

Claims

1. A thermoplastic resin molded product comprising a resin having water vapor barrier properties and a resin having oxygen barrier properties, wherein the resin having oxygen barrier properties exists as islands in the resin having water vapor barrier properties to form a dispersed phase, The size of the dispersed phase varies depending on the depth in the thickness direction of the thermoplastic resin molded body, and the average value of the cross-sectional area of ​​the dispersed phase is 0.05 μm in a cross section parallel to the molding direction and thickness direction of the thermoplastic resin molded body in the front and back regions. ２ 0.80 μm or more ２ or less, and in a cross section parallel to the molding width direction and thickness direction of the thermoplastic resin molded body in the intermediate region, the average cross-sectional area of ​​the dispersed phase is 1.00 μm ２ 400 μm or more ２ is as follows: The thickness of the front and back regions is 5 μm or more and 20 μm or less, A thermoplastic resin molded body, characterized in that the thickness of the intermediate region is 20 μm or more.

2. The thermoplastic resin molded body according to claim 1, characterized in that the resin having oxygen barrier properties that forms the dispersed phase is divided into at least three regions: the front and back regions and the middle region of the thermoplastic resin molded body.

3. 3. The thermoplastic resin molded body according to claim 1, wherein the mass ratio of the resin having oxygen barrier properties to the thermoplastic resin molded body is 15 mass % or more and 40 mass % or less.

4. A thermoplastic resin molded body according to any one of claims 1 to 3, characterized in that in the intermediate region, the aspect ratio of the dispersed phase when viewed from the molding direction is 15 or more and 100 or less, and the aspect ratio when viewed from the molding width direction is 15 or more and 100 or less.

5. 5. The thermoplastic resin molded body according to claim 1, further comprising a resin having a functional group, the resin having a functional group comprising a copolymer of an olefin and a functional group-containing monomer, the resin having a functional group being different from the resin having water vapor barrier property, the functional group having a reactive group capable of bonding with the resin having oxygen barrier property, and the resin having a functional group having a core-shell structure encapsulating the resin having oxygen barrier property.

6. A packaging material comprising the thermoplastic resin molded article according to any one of claims 1 to 5.

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