Extrusion moldings for tube containers and tube containers

Abstract

To provide a technique for an extruded tube containing a plant-derived polyethylene resin, and having excellent stress crack resistance, interlayer adhesion strength and manufacturing stability.SOLUTION: An extruded product for a tube container has a tube shape as a whole, and has a three-layer structure consisting of an inner layer, an outer layer, and an intermediate layer interposed therebetween, in which the inner layer and the outer layer contains an acid-modified polyethylene resin derived from petroleum and a linear low-density polyethylene resin derived from a plant, respectively.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an extrusion molded product for a tubular container and a tubular container. [Background technology]

[0002] Laminated tubes are known as tube containers for storing toothpaste, cosmetics, etc. Laminated tubes are manufactured using a laminated sheet made by laminating polyethylene resin, specialty paper, aluminum foil, etc. Generally, laminated tubes are manufactured by rolling the laminated sheet into a cylindrical shape, overlapping both ends of the sheet, welding the overlapped portions, and joining a cap fitting portion to the resulting container body.

[0003] Such laminated tubes have the following problems, for example: Because laminated tubes are manufactured by overlapping both ends, a step occurs at the overlapped portion, resulting in an appearance problem. Because the end faces of the laminated sheet are exposed at the overlapped portion, the contents contained therein permeate the laminate from the end faces, degrading the physical properties of the laminated sheet. Furthermore, because laminated tubes include a process of rolling them into a cylindrical shape and because it is desirable to make the above-mentioned step less noticeable, it is difficult to increase the wall thickness, and it is difficult to maintain sufficient strength in tubes with large diameters.

[0004] To solve the above problems of laminated tubes, it has been proposed to manufacture the container body of a tube container by extrusion molding (Patent Documents 1 and 2). A tube container manufactured by extrusion molding is called an extrusion-molded tube. An extrusion-molded tube is manufactured by continuously extruding molten resin into a tube shape using an extruder, then cutting it to an appropriate length, and joining a cap fitting portion to the resulting container body. In the case of a multilayer extrusion-molded tube, it is manufactured by extruding multiple types of molten resin into a single mold using separate extruders and forming a multilayered tube shape within the mold.

[0005] Most of the tube containers currently on the market are made from petroleum-derived resins. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-309406 [Patent Document 2] Japanese Patent Application Publication No. 11-309785 Summary of the Invention [Problem to be solved by the invention]

[0007] In order to overcome the above problems associated with laminated tubes and to protect the environment, the present inventors have attempted to develop an extrusion-molded tube containing a plant-derived polyethylene resin, but have discovered the following new problems.

[0008] When plant-derived polyethylene resin was used instead of petroleum-derived polyethylene resin, the extrusion-molded tube was prone to stress cracking. Furthermore, when a multilayer extrusion-molded tube consisting of a resin layer containing plant-derived polyethylene resin and a resin layer with gas barrier properties was produced, it was prone to interlayer delamination. Furthermore, when such a multilayer extrusion-molded tube was continuously molded, deformation occurred after extrusion into a tubular shape.

[0009] Therefore, an object of the present invention is to provide a technology relating to an extrusion-molded tube that contains a plant-derived polyethylene resin and has excellent stress crack resistance, interlayer adhesion strength, and manufacturing stability. [Means for solving the problem]

[0010] According to one aspect of the present invention, there is provided an extrusion-molded product for a tubular container, which has an overall tubular shape and a three-layer structure consisting of an inner layer, an outer layer, and an intermediate layer interposed therebetween, wherein the inner layer and the outer layer each contain a petroleum-derived acid-modified polyethylene resin and a plant-derived linear low-density polyethylene resin.

[0011] According to another aspect of the present invention, a container body including the above-mentioned extrusion molded product, one end of which is heat-sealed; a cap fitting portion joined to the other end of the extrusion molded product whose one end has been heat-sealed; A tube container comprising: [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an extrusion-molded tube that contains a plant-derived polyethylene resin and has excellent stress crack resistance, interlayer adhesion strength, and production stability. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a three-layer structure of an extrusion molded product according to one embodiment of the present invention. [Figure 2] FIG. 1 is a plan view showing a configuration of a tube container according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described below. However, the following description is intended to explain the present invention in detail and is not intended to limit the present invention.

[0015] 1. Extrusion moldings for tube containers The extrusion-molded product for tubular containers has an overall tubular shape and a three-layer structure consisting of an inner layer, an outer layer, and an intermediate layer interposed therebetween, and the inner layer and the outer layer each contain a petroleum-derived acid-modified polyethylene resin and a plant-derived linear low-density polyethylene resin. In the following description, the extrusion-molded product for tubular containers will be simply referred to as an "extrusion-molded product."

[0016] 1-1. Structure The extrusion-molded product has an overall tubular shape and a three-layer structure consisting of an inner layer, an outer layer, and an intermediate layer interposed therebetween. FIG. 1 is a cross-sectional view showing the three-layer structure of an extrusion-molded product according to one embodiment of the present invention. As shown in FIG. 1, the extrusion-molded product 1 has a three-layer structure consisting of an inner layer 1a, an outer layer 1c, and an intermediate layer 1b interposed therebetween. When the extrusion-molded product 1 shown in FIG. 1 is used as the container body of a tubular container, the surface on the inner layer 1a side is adjacent to the internal space of the tubular container, and the surface on the outer layer 1c side is adjacent to the external space of the tubular container.

[0017] The extrusion-molded product 1 may be cylindrical or elliptical. The extrusion-molded product 1 has a circumferential length of, for example, 30 to 190 mm. The extrusion-molded product 1 preferably has a circumferential length of 40 to 160 mm. The circumferential length refers to the outer periphery of the tubular extrusion-molded product 1. The extrusion-molded product 1 has a thickness of, for example, 0.19 to 0.55 mm, preferably 0.24 to 0.5 mm. The thickness refers to the thickness of the wall of the tubular extrusion-molded product 1 and is the average value of thicknesses measured at three points set at approximately equal intervals along the longitudinal direction of the extrusion-molded product 1. The inner layer 1a has a thickness of, for example, 0.12 to 0.25 mm, preferably 0.14 to 0.24 mm, the intermediate layer 1b has a thickness of, for example, 0.01 to 0.1 mm, preferably 0.02 to 0.08 mm, and the outer layer 1c has a thickness of, for example, 0.06 to 0.2 mm, preferably 0.08 to 0.18 mm.

[0018] The extrusion molded product 1 can have any length, and may be longer than the container body of the tubular container, or may be the same length as the container body of the tubular container. In the former case, the extrusion molded product 1 is cut to the length of the container body of the tubular container and then used as the container body of the tubular container.

[0019] 1-2.Resin The resins constituting the inner layer 1a, intermediate layer 1b, and outer layer 1c will be described below.

[0020] (Inner layer 1a) The inner layer 1a contains a "petroleum-derived acid-modified polyethylene resin" and a "plant-derived linear low-density polyethylene resin."

[0021] "Petroleum-derived acid-modified polyethylene resin" "Petroleum-derived acid-modified polyethylene resin" is a resin obtained by modifying petroleum-derived polyethylene with an unsaturated carboxylic acid or its anhydride. Such resins are known as adhesive resins because the adhesive properties are imparted by the acid modification. Examples of unsaturated carboxylic acids or their anhydrides include acrylic acid, methacrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, chloromaleic acid, butenylsuccinic acid, and their anhydrides.

[0022] The "petroleum-derived acid-modified polyethylene resin" is preferably a petroleum-derived maleic anhydride-modified polyethylene resin. More preferably, the "petroleum-derived acid-modified polyethylene resin" is a petroleum-derived maleic anhydride-modified low-density polyethylene resin (MA-modified LDPE), a petroleum-derived maleic anhydride-modified linear low-density polyethylene resin (MA-modified L-LDPE), or a mixture thereof.

[0023] "Petroleum-derived maleic anhydride-modified low-density polyethylene resin (MA-modified LDPE)" is a resin obtained by modifying a homopolymer of ethylene, which is produced using petroleum as a raw material, with maleic anhydride.

[0024] The density of "petroleum-derived maleic anhydride modified low-density polyethylene resin (MA modified LDPE)" is 0.91 g / cm 3 ~0.93g / cm 3 and preferably in the range of 0.915 g / cm 3 ~0.93g / cm 3 It is more preferable that the density of the resin described in this specification is a measured value obtained by a method in accordance with JIS K7112:1999.

[0025] Furthermore, the melt flow rate (MFR) of the "petroleum-derived maleic anhydride-modified low-density polyethylene resin (MA-modified LDPE)" is preferably in the range of 0.1 g / 10 min to 10 g / 10 min, and more preferably in the range of 1 g / 10 min to 5 g / 10 min. The melt flow rate (MFR) of the resin described in this specification is a measured value obtained by a method conforming to JIS K7210:1999. Specifically, the melt flow rate is a measured value of the weight of resin extruded in 10 minutes when a load of 21.18 N (2.16 kgf) is applied to the resin at 190°C.

[0026] Examples of the "petroleum-derived maleic anhydride-modified low-density polyethylene resin (MA-modified LDPE)" that can be used include a resin sold by Mitsubishi Chemical Corporation under the trade name "Modic" (registered trademark) and a resin sold by Mitsui Chemicals, Inc. under the trade name "Admer" (registered trademark).

[0027] "Petroleum-derived maleic anhydride-modified linear low-density polyethylene resin (MA-modified L-LDPE)" is a resin obtained by modifying a copolymer of ethylene and an α-olefin, which is produced using petroleum as a raw material, with maleic anhydride. The "α-olefin" is at least one compound selected from the group consisting of α-olefins having 3 to 20 carbon atoms, such as 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

[0028] The density of "petroleum-derived maleic anhydride modified linear low-density polyethylene resin (MA modified L-LDPE)" is 0.91 g / cm 3 ~0.93g / cm 3 and preferably in the range of 0.915 g / cm 3 ~0.93g / cm 3 Furthermore, the melt flow rate (MFR) of the "petroleum-derived maleic anhydride-modified linear low-density polyethylene resin (MA-modified L-LDPE)" is preferably in the range of 0.1 g / 10 min to 10 g / 10 min, and more preferably in the range of 1 g / 10 min to 5 g / 10 min.

[0029] Examples of "petroleum-derived maleic anhydride-modified linear low-density polyethylene resin (MA-modified L-LDPE)" that can be used include resins sold by Mitsui Chemicals, Inc. under the trade name "Admer" (registered trademark), resins sold by Mitsubishi Chemical Corporation under the trade name "Modic" (registered trademark), and resins sold by ARKEMA under the trade name "OREVAC" (registered trademark).

[0030] "Plant-derived linear low-density polyethylene resin" "Plant-derived linear low-density polyethylene resin (bio-L-LDPE)" is a copolymer of ethylene and α-olefin produced using plants as raw materials. "Plant-derived linear low-density polyethylene resin (bio-L-LDPE)" is preferably a sugarcane-derived linear low-density polyethylene resin. Sugarcane-derived linear low-density polyethylene resin is a copolymer of ethylene and α-olefin produced using sugarcane as raw material.

[0031] The "α-olefin" is at least one compound selected from the group consisting of α-olefins having 3 to 20 carbon atoms, and examples thereof include 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

[0032] The density of "plant-derived linear low-density polyethylene resin (Bio-L-LDPE)" is 0.91 g / cm 3 ~0.93g / cm 3 and preferably in the range of 0.915 g / cm 3 ~0.93g / cm 3 In addition, the melt flow rate (MFR) of the "plant-derived linear low-density polyethylene resin (bio-L-LDPE)" is preferably in the range of 0.1 g / 10 min to 10 g / 10 min, and more preferably in the range of 1 g / 10 min to 5 g / 10 min.

[0033] As the "plant-derived linear low-density polyethylene resin (bio-L-LDPE)", for example, plant-derived linear low-density polyethylene sold by Braskem can be used, and examples thereof include resins sold under the trade names SLL118, SLL118 / 21, SLL218, SLL218 / 21, SLL318, SLH118, SLH218, and SLH0820 / 30AF.

[0034] The inner layer 1a can contain the "petroleum-derived acid-modified polyethylene resin" and the "plant-derived linear low-density polyethylene resin" in a mass ratio of, for example, 9:1 to 4:6. The inner layer 1a can contain the "petroleum-derived acid-modified polyethylene resin" and the "plant-derived linear low-density polyethylene resin" in a mass ratio of, for example, 9:1 to 5:5.

[0035] (middle layer 1b) The intermediate layer 1b preferably contains a resin having gas barrier properties. The resin constituting the intermediate layer 1b can be a resin known to have gas barrier properties. Examples of the resin constituting the intermediate layer 1b include ethylene-vinyl alcohol copolymer resin (EVOH), nylon (NY), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), and polyvinylidene chloride (PVDC), and ethylene-vinyl alcohol copolymer resin (EVOH) is preferred.

[0036] Examples of ethylene-vinyl alcohol copolymer resins (EVOH) that can be used include resins sold by Mitsubishi Chemical Corporation under the trade name "Soarnol" (registered trademark) and resins sold by Kuraray Co., Ltd. under the trade name "Eval" (registered trademark).

[0037] (outer layer 1c) The outer layer 1c contains a "petroleum-derived acid-modified polyethylene resin" and a "plant-derived linear low-density polyethylene resin." The "petroleum-derived acid-modified polyethylene resin" contained in the outer layer 1c is as described for the inner layer 1a. The "plant-derived linear low-density polyethylene resin" contained in the outer layer 1c is as described for the inner layer 1a.

[0038] The outer layer 1c can contain the "petroleum-derived acid-modified polyethylene resin" and the "plant-derived linear low-density polyethylene resin" in a mass ratio of, for example, 9:1 to 4:6. The outer layer 1c can contain the "petroleum-derived acid-modified polyethylene resin" and the "plant-derived linear low-density polyethylene resin" in a mass ratio of, for example, 9:1 to 5:5.

[0039] The outer layer 1c may have the same resin composition as the inner layer 1a, or may have a resin composition different from that of the inner layer 1a.

[0040] (additives) The inner layer 1a, intermediate layer 1b, and outer layer 1c are primarily composed of resin, but may contain known additives in addition to the resin, as needed. Various additives known as resin additives can be used. Examples of additives include antioxidants, UV absorbers, weathering agents, antistatic agents, fillers, nucleating agents, color pigments, delustering agents, color inhibitors, anti-fogging agents, flame retardants, anti-blocking agents, and lubricants (including slip agents and mold release agents). The total content of the additives can be, for example, 0.01 to 10 parts by mass per 100 parts by mass of the resin in each layer.

[0041] 1-3. Manufacturing method The extrusion-molded product 1 can be produced by a known co-extrusion method, that is, by extruding the resins constituting the inner layer 1a, the intermediate layer 1b, and the outer layer 1c into a single mold using separate extruders, and forming a three-layer tubular shape within the mold.

[0042] 2. Tube container The tube container is a container body including the above-mentioned extrusion molded product, one end of which is heat-sealed; a cap fitting portion joined to the other end of the extrusion molded product whose one end has been heat-sealed; It is equipped with:

[0043] A tube container according to one embodiment of the present invention will be described below with reference to Fig. 2. Fig. 2 is a plan view showing the configuration of a tube container according to one embodiment of the present invention.

[0044] As shown in Fig. 2, the tube container 1 includes a container body 11 and a cap fitting portion 12 joined to the container body 11. The tube container 1 is used by filling the container body 11 with contents and fitting a cap into the cap fitting portion 12. Here, the contents may be a highly viscous liquid or a semi-solid. Examples of the contents include daily necessities such as facial cleanser, cosmetics, toothpaste, and hand cream, and foods such as jam and butter.

[0045] The container body 11 is obtained by heat-sealing one end of the above-described extrusion-molded product 1. Note that a printed layer may be provided on the outer surface of the extrusion-molded product 1 before heat-sealing one end. That is, the container body 11 may further include a printed layer.

[0046] As shown in FIG. 2, the container body 11 includes a body portion 21 and a seal portion 22 provided at one end of the body portion 21.

[0047] The body portion 21 is a non-heat-sealed portion of the extrusion-molded product 1. The end portion of the body portion 21 where the sealed portion 22 is not provided has a circular or elliptical cylindrical shape when viewed from the opening.

[0048] The sealed portion 22 is a portion formed by thermally welding one end of the extrusion-molded product 1. The sealed portion 22 has a flat shape, and the opposing inner surfaces thereof are heat-sealed. The sealed portion 22 closes one end of the container body 11.

[0049] A cap fitting portion 12 is provided at the end of the body portion 21 opposite to the end where the seal portion 22 is provided. The cap fitting portion 12 has a shoulder portion 31 that is integrally continuous with the end of the body portion 21 where the seal portion 22 is not provided, and a cylindrical mouth portion 32 provided in the center of the shoulder portion 31. The cap fitting portion 12 is manufactured separately from the body portion 21 by injection molding or compression molding, and is joined to the body portion 21.

[0050] The shoulder 31 has an outer surface facing the exterior space of the tube container 10 and an inner surface facing the interior space of the tube container 10, each of which has a truncated cone shape tapering from the interior space to the exterior space. The outer periphery of the shoulder 31 is continuous with the body 21. The mouth 32 is provided at the center of the shoulder 31 so as to protrude outward.

[0051] 3.Effects The extrusion-molded product of the present invention and the tubular container containing the same contain a combination of a "petroleum-derived acid-modified polyethylene resin" and a "plant-derived linear low-density polyethylene resin" in each of the inner and outer layers of the three-layer structure. By using this specific resin combination, the present invention can achieve excellent stress crack resistance, excellent interlayer adhesion strength, and excellent manufacturing stability, even when a plant-derived polyethylene resin is blended (see Examples below).

[0052] The extrusion-molded product of the present invention and a tubular container containing the same also have the following advantages. Because the extrusion-molded product of the present invention and a tubular container containing the same contain a plant-derived polyethylene resin, they can contribute to reducing CO2 emissions compared to petroleum-derived polyethylene resins. Furthermore, because the extrusion-molded product of the present invention and a tubular container containing the same are produced by extrusion molding, they do not have the overlapping portions (i.e., seams) seen in laminated tubes, and can achieve a seamless appearance. Furthermore, because the extrusion-molded product of the present invention and a tubular container containing the same are produced by extrusion molding, they can be easily made thicker than laminated tubes, and even large-diameter tubular containers can maintain sufficient strength. [Example]

[0053] [Example 1] [1-1] Manufacturing of extrusion molded products The following resins A to E were prepared as resins for the inner and outer layers.

[0054] Resin A: Petroleum-derived maleic anhydride-modified low-density polyethylene (density: 0.93 g / cm 3 , MFR: 1.0 g / 10 min (190 ° C, 2.16 kg load)) (hereinafter referred to as "MA-modified LDPE-1"); Resin B: Petroleum-derived maleic anhydride-modified low-density polyethylene (density: 0.92 g / cm 3 , MFR: 1.5 g / 10 min (190 ° C, 2.16 kg load)) (hereinafter referred to as "MA-modified LDPE-2"); Resin C: Petroleum-derived maleic anhydride-modified linear low-density polyethylene (density: 0.926 g / cm 3 , MFR: 1.2 g / 10 min (190 ° C, 2.16 kg load)) (hereinafter referred to as "MA-modified L-LDPE"); Resin D: Plant-derived low-density polyethylene (density: 0.923 g / cm 3 , MFR: 2.7g / 10min (190℃, 2.16kg load)) (hereinafter referred to as "bio-LDPE"); Resin E: Plant-derived linear low-density polyethylene (density: 0.916 g / cm 3 , MFR: 1.0 g / 10 min (190°C, 2.16 kg load) (hereinafter referred to as "Bio L-LDPE").

[0055] The resin for the intermediate layer (barrier layer) was ethylene-vinyl alcohol copolymer (density: 1.14 g / cm 3 , MFR: 12.0 g / 10 min (210°C, 2.16 kg load) (hereinafter referred to as "EVOH") was prepared.

[0056] <Example 1A> The resins constituting the inner and outer layers were a mixed resin obtained by dry blending MA-modified LDPE-1 and bio-LDPE in a 50:50 mass ratio. 0.1 mass parts of antioxidant and 2.5 mass parts of titanium dioxide (titanium dioxide) as a coloring pigment were added to 100 mass parts of the mixed resin to obtain a mixture. Pellets of the above mixture and pellets of ethylene-vinyl alcohol copolymer were loaded into the two hoppers of a single-screw tube extruder. The extruder and die temperatures were set to 170-200°C, and a production rate of 60 tubes / min and a take-up speed of 6.1 m / min were used to extrude a three-layer tube (outer layer / middle layer / inner layer). The resulting tube (i.e., extrusion molded product) had a circumference of 93.2 mm, a length of 100 mm, and an average wall thickness of 0.46 mm.

[0057] <Example 1B> A tube was produced in the same manner as in Example 1A, except that a mixed resin obtained by dry blending MA-modified LDPE-1, MA-modified L-LDPE, and bio-LDPE in a mass ratio of 50:20:30 was used as the resin constituting the inner layer and outer layer.

[0058] <Example 1C> A tube was produced in the same manner as in Example 1A, except that a mixed resin obtained by dry blending MA-modified LDPE-1 and bio-L-LDPE in a mass ratio of 50:50 was used as the resin constituting the inner layer and outer layer.

[0059] <Example 1D> A tube was produced in the same manner as in Example 1A, except that a mixed resin obtained by dry blending MA-modified LDPE-1, MA-modified L-LDPE, and bio-L-LDPE in a mass ratio of 50:20:30 was used as the resin constituting the inner layer and outer layer.

[0060] <Example 1E> A tube was produced in the same manner as in Example 1A, except that the resins constituting the inner and outer layers were mixed resins obtained by dry blending MA-modified LDPE-1, MA-modified LDPE-2, and bio-L-LDPE in a mass ratio of 50:20:30, respectively.

[0061] <Example 1F> A tube was produced in the same manner as in Example 1A, except that the resins constituting the inner and outer layers were mixed resins obtained by dry blending MA-modified LDPE-1, MA-modified L-LDPE, and bio-LDPE in a mass ratio of 60:30:10, respectively.

[0062] [1-2] Evaluation method The physical properties of the tubes of Examples 1A to 1F were evaluated by the following methods.

[0063] <Stress crack resistance (ESCR resistance)> One end of the resulting tube was heat-sealed, and a 5 cm section was cut from the end to serve as a test specimen. This test specimen was immersed in a 10% Igepal aqueous solution and stored in a 65°C thermostatic chamber for 168 hours. After storage, the presence or absence of cracks was visually determined. Evaluation criteria 〇: No cracks △: Minor cracks are observed ×: Large cracks are observed (leading to leakage of contents)

[0064] <Interlayer adhesion strength> The resulting tube was cut open and cut into 15 mm wide strips to prepare test specimens. The test specimens were partially peeled between the inner and intermediate layers, and the unpeeled portion of the test specimen was opened 180° with the center at the center. The specimens were then attached to the grips of a tensile tester (Shimadzu Corporation, trade name: AUTOGRAPH AGS-X). A T-type tensile test was performed at a tensile speed of 50 mm / min, and the stable value was recorded as the interlayer adhesion strength. Evaluation criteria 〇: 1.0 kgf or more △: 0.4 kgf or more, less than 1.0 kgf ×: Less than 0.4 kgf

[0065] <Continuous molding> When the tube was continuously molded, it was visually confirmed whether deformation occurred in the molded product. Evaluation criteria 〇: No deformation ×: Deformed

[0066] [1-3] Evaluation results The resin compositions of each layer of the tubes of Examples 1A to 1F and the evaluation results are shown in the following Tables 1 and 2. The numbers in the tables represent parts by mass.

[0067] [Table 1]

[0068] [Table 2]

[0069] In Examples 1A, 1B, and 1F, the inner and outer layers of the tube each contain a combination of "petroleum-derived acid-modified polyethylene resin" and "plant-derived low-density polyethylene resin (bio-LDPE)." In these examples, as the amount of plant-derived polyethylene resin added increased, stress crack resistance decreased, interlayer adhesion strength decreased slightly, and deformation of the molded product was observed after continuous molding.

[0070] On the other hand, in Examples 1C, 1D, and 1E, the inner and outer layers of the tube each contain a combination of "petroleum-derived acid-modified polyethylene resin" and "plant-derived linear low-density polyethylene resin (bio-L-LDPE)." In these examples, even when the amount of plant-derived polyethylene resin added was increased, excellent stress crack resistance was exhibited, interlayer adhesion strength (0.4 kgf or more) was not a problem in terms of quality, and no deformation was observed in the molded product after continuous molding.

[0071] [Example 2] Various tubes were manufactured by varying the amount of plant-derived linear low-density polyethylene resin (Bio-L-LDPE) and the circumference of the tube, and the effects of the amount of Bio-L-LDPE and the circumference of the tube on stress crack resistance, interlayer adhesion strength, and continuous moldability were investigated.

[0072] [2-1] Tube manufacturing <Example 2A> Tubes were produced in the same manner as in Example 1A, using a mixed resin obtained by dry blending MA-modified LDPE-1, MA-modified LDPE-2, and bio-L-LDPE in a mass ratio of 60:10:10 as the resins constituting the inner and outer layers. The circumferences of the tubes (i.e., extrusion-molded products) were 20 mm, 60 mm, 100 mm, 160 mm, 180 mm, and 200 mm. The length of the tube was 100 mm, and the average wall thickness was 0.46 mm.

[0073] <Example 2B> Tubes were produced in the same manner as in Example 1A, using a mixed resin obtained by dry blending MA-modified LDPE-1, MA-modified LDPE-2, and bio-L-LDPE in a mass ratio of 50:20:30 as the resins constituting the inner and outer layers. The circumferences of the tubes (i.e., extrusion-molded products) were 20 mm, 60 mm, 100 mm, 160 mm, 180 mm, and 200 mm. The length of the tube was 100 mm, and the average wall thickness was 0.46 mm.

[0074] <Example 2C> Tubes were produced in the same manner as in Example 1A, using a mixed resin obtained by dry blending MA-modified LDPE-1, MA-modified LDPE-2, and bio-L-LDPE in a mass ratio of 40:10:50 as the resin constituting the inner and outer layers. The circumferences of the tubes (i.e., extrusion-molded products) were 20 mm, 60 mm, 100 mm, 160 mm, 180 mm, and 200 mm. The length of the tube was 100 mm, and the average wall thickness was 0.46 mm.

[0075] [2-2] Evaluation method As described in section [1-2], stress crack resistance, interlayer peel adhesion strength, and continuous formability were evaluated.

[0076] [2-3] Evaluation results Example 2A (when the blending amount of plant-derived polyethylene resin is 10% by mass) In Example 2A, no cracks were observed in the stress crack resistance test regardless of the tube circumference. Furthermore, in Example 2A, no quality problems were observed in the interlayer adhesion strength regardless of the tube circumference. Furthermore, in Example 2A, no deformation was observed in the molded product after continuous molding regardless of the tube circumference.

[0077] Example 2B (when the blending amount of plant-derived polyethylene resin is 30% by mass) In Example 2B, no cracks were observed in the stress crack resistance test for any tube circumference. Furthermore, in Example 2B, a tendency for interlayer adhesion strength to decrease was observed for tubes with smaller circumferences, but for any tube circumference, interlayer adhesion strength sufficient to pose no quality problems was observed. Furthermore, in Example 2B, no deformation was observed in the molded product after continuous molding for any tube circumference.

[0078] Example 2C (when the blending amount of plant-derived polyethylene resin is 50% by mass) In Example 2C, no cracks were observed in the stress crack resistance test, regardless of the tube's circumference. In Example 2C, while a tendency for interlayer adhesion strength to decrease was observed for tubes with small and large circumferences, the tube exhibited interlayer adhesion strength sufficient to pose no quality problems, regardless of the tube's circumference. In Example 2C, no deformation was observed in the molded product after continuous molding, regardless of the tube's circumference.

[0079] These results indicate that excellent stress crack resistance, excellent interlayer adhesion strength, and excellent manufacturing stability can be achieved even when the amount of plant-derived polyethylene resin blended and the circumference of the tube are changed. The following claims as originally filed in this application are appended as embodiments. [1] An extrusion-molded product for a tube container, which has an overall tubular shape and a three-layer structure consisting of an inner layer, an outer layer, and an intermediate layer interposed therebetween, and each of the inner layer and the outer layer contains a petroleum-derived acid-modified polyethylene resin and a plant-derived linear low-density polyethylene resin. [2] The extrusion molded product according to [1], wherein the linear low-density polyethylene resin is a linear low-density polyethylene resin derived from sugarcane. [3] The extrusion molded product according to [1] or [2], wherein the acid-modified polyethylene resin is a petroleum-derived maleic anhydride-modified low-density polyethylene resin, a petroleum-derived maleic anhydride-modified linear low-density polyethylene resin, or a mixture thereof. [4] The extrusion-molded product according to any one of [1] to [3], wherein the intermediate layer contains a resin having gas barrier properties. [5] The extrusion-molded product according to any one of [1] to [4], wherein the inner layer and the outer layer each contain a petroleum-derived acid-modified polyethylene resin and a plant-derived linear low-density polyethylene resin in a mass ratio of 9:1 to 4:6. [6] The extrusion molded product according to any one of [1] to [5], having a circumferential length of 30 to 190 mm. [7] A container body including the extrusion-molded product according to any one of [1] to [6], one end of which is heat-sealed; a cap fitting portion joined to the other end of the extrusion molded product whose one end has been heat-sealed; A tube container comprising: [Explanation of symbols]

[0080] 1...extrusion molded product, 1a...inner layer, 1b...intermediate layer, 1c...outer layer, 10...tube container, 11...container body, 12...cap fitting portion, 21...body portion, 22...seal portion, 31...shoulder portion, 32...mouth portion.

Claims

1. The extrusion-molded product for a tube container has a tubular shape as a whole and has a three-layer structure consisting of an inner layer, an outer layer, and an intermediate layer interposed therebetween, and the inner layer and the outer layer each contain a petroleum-derived acid-modified polyethylene resin and a plant-derived linear low-density polyethylene resin in a mass ratio of 9:1 to 4:

6.

2. 2. The extrusion molded product according to claim 1, wherein the linear low-density polyethylene resin is a linear low-density polyethylene resin derived from sugarcane.

3. 3. The extrusion molded product according to claim 1, wherein the acid-modified polyethylene resin is a petroleum-derived maleic anhydride-modified low-density polyethylene resin, a petroleum-derived maleic anhydride-modified linear low-density polyethylene resin, or a mixture thereof.

4. The extrusion molded product according to any one of claims 1 to 3, wherein the intermediate layer contains a resin having gas barrier properties.

5. 5. The extrusion-molded product according to claim 1, wherein each of the inner layer and the outer layer contains a petroleum-derived acid-modified polyethylene resin and a plant-derived linear low-density polyethylene resin in a mass ratio of 9:1 to 5:

5.

6. The extrusion molded product according to any one of claims 1 to 5, having a circumferential length of 30 to 190 mm.

7. A container body comprising the extrusion molded product according to any one of claims 1 to 6, one end of which is heat-sealed; a cap fitting portion joined to the other end of the extrusion molded product whose one end has been heat-sealed; A tube container comprising:

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