Method of manufacturing resin product, and resin product

Abstract

To provide a method of manufacturing a resin product, and the resin product capable of preventing an occurrence of melt fracture during extrusion even when a blending ratio of plant-derived polyethylene is 50 mass% or more.SOLUTION: A method of manufacturing a resin product manufactures the resin product through an extrusion step of extruding a resin material in a molten state. The resin material contains 50 mass% or more of plant-derived polyethylene, and 3 mass% or more of high melt tension polypropylene relative to 100 mass% of the resin material. A resin product formed by extrusion blow molding or extrusion molding contains 50 mass% or more of the plant-derived polyethylene, and 3 mass % or more of the high melt tension polypropylene relative to 100 mass% of the resin material that forms the resin product.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a resin product and a resin product. [Background technology]

[0002] Resin products containing plant-derived polyethylene are known for the purpose of saving petroleum resources and the like (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-73322 Summary of the Invention [Problem to be solved by the invention]

[0004] When resin products such as those described above are manufactured through an extrusion process in which molten resin material is extruded by extrusion blow molding, extrusion molding, or the like, if the blending ratio of plant-derived polyethylene is 50% by mass or more, melt fracture (a phenomenon in which the surface becomes rough and uneven) may occur during extrusion.

[0005] Therefore, an object of the present invention is to provide a method for producing a resin product, and a resin product, which can suppress the occurrence of melt fracture during extrusion even when the blending ratio of plant-derived polyethylene is 50% by mass or more. [Means for solving the problem]

[0006] One aspect of the present invention is as follows.

[0007] [1] A resin product is manufactured through an extrusion process in which molten resin material is extruded. The resin material contains 50% by mass or more of plant-derived polyethylene and 3% by mass or more of high melt tension polypropylene relative to 100% by mass of the resin material.

[0008] [2] The method for manufacturing a resin product according to [1], wherein the surface roughness Rz of the resin product is 30 μm or less.

[0009] [3] The method for manufacturing a resin product according to [1] or [2], wherein the resin product does not contain a fluorescent whitening agent.

[0010] [4] The method for producing a resin product according to any one of [1] to [3], wherein the resin product is a blow-molded container or a tube container.

[0011] [5] A resin product formed by extrusion blow molding or extrusion molding, A resin product containing 50% by mass or more of plant-derived polyethylene and 3% by mass or more of high melt tension polypropylene relative to 100% by mass of a resin material forming the resin product. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for producing a resin product, and a resin product, in which the occurrence of melt fracture during extrusion can be suppressed even when the blending ratio of plant-derived polyethylene is 50% by mass or more. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is an explanatory diagram showing the results of a test conducted to examine the relationship between the blending ratio of high melt tension polypropylene and the occurrence of melt fracture in a resin product manufacturing method according to one embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory diagram for supplementing the test results shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] In one embodiment of the present invention, a method for producing a resin product includes an extrusion process in which a molten resin material is extruded to produce a resin product. The resin material contains, relative to 100% by mass of the resin material, 50% by mass or more of plant-derived polyethylene (also known as bio-PE) and 3% by mass or more (preferably 3% by mass or more and 5% by mass or less) of high melt tension polypropylene (also known as high melt tension PP). In other words, in this embodiment, the resin product is formed by extrusion blow molding, extrusion molding, or the like, and contains, relative to 100% by mass of the resin material forming the resin product, 50% by mass or more of plant-derived polyethylene and 3% by mass or more (preferably 3% by mass or more and 5% by mass or less) of high melt tension polypropylene. The resin product is, for example, a blow-molded container formed by extrusion blow molding, or a tubular container formed by extrusion molding.

[0016] The resin product of this embodiment does not contain a fluorescent whitening agent. Therefore, it is suitable for use in food containers or their components where contact with the contents is prohibited. Plant-derived HDPE (also known as bio-HDPE; high-density polyethylene) may be used as the bio-PE. In this case, the bio-HDPE provides moisture resistance, making it particularly suitable for use in food containers or their components.

[0017] There are no particular limitations on the high melt tension PP, as long as it is what is generally referred to as high melt tension polypropylene. For example, by introducing a long chain branching structure during the polymerization stage, high melt tension (2 to 10 times that of conventional PP) compared to conventional PP is imparted with the following characteristics: high viscosity, high melt tension (2 to 10 times that of conventional PP), low temperature dependency, high strain hardening, and high recyclability (remeltable).

[0018] Conventional bio-PE, which is suitable for extrusion processing, cannot be used for food products because it contains fluorescent brighteners. If a bio-PE that does not contain fluorescent brighteners is used instead, melt fracture occurs when the bio-PE blend ratio is increased. However, a test whose results are shown in Figure 1 revealed that the occurrence of melt fracture can be suppressed by further blending high melt tension PP.

[0019] In this test, the resin material was made up of bio-HDPE (bio-PE), petroleum-derived HDPE (petroleum-derived PE), a coloring masterbatch (coloring MB), and high melt tension PP. As shown in Figure 1, melt fracture occurred when the bio-PE content was increased to 50% by mass (see Samples 1 to 3).

[0020] The occurrence of melt fracture was judged by visually evaluating the roughness of the surface of the resin product. Products with a "poor" appearance were judged to have had melt fracture, and products with an "excellent" or "good" appearance were judged to have not had melt fracture.

[0021] The results in Figure 1 (see Samples 4-7) indicate that melt fracture can be suppressed by configuring the resin material to contain 50% or more by mass of bio-PE and 3% or more by mass of high-melt tension PP. Furthermore, the results in Figure 1 (see Samples 6-7) also indicate that a high-melt tension PP content of 5% by mass is sufficient to suppress melt fracture. High-melt tension PP may be added in excess of 5% by mass, but this reduces the bio-PE content and environmental friendliness, which is undesirable. While colored MB was used in this test, similar effects can be achieved even without colored MB.

[0022] The surface roughness Rz of a resin product can be measured using a coordinate measuring machine, and if the value is 30 μm or less, it can be determined that no melt fracture has occurred. Figure 2 shows the appearance photographs of Samples 1 to 3 and 5, along with the measured surface roughness Rz values. The results in Figure 2 indicate that the surface roughness becomes rough when the surface roughness Rz exceeds approximately 30 μm (see Sample 3). The results in Figure 2 also indicate that the addition of high melt tension PP improved the surface roughness to the same level as when no bio-PE was added (see Samples 1 and 5).

[0023] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be modified in various ways without departing from the gist of the present invention.

Claims

1. A resin product is manufactured through an extrusion process in which molten resin material is extruded. The resin material contains 50% by mass or more of plant-derived polyethylene and 3% by mass or more of high melt tension polypropylene relative to 100% by mass of the resin material.

2. 2. The method for manufacturing a resin product according to claim 1, wherein the surface roughness Rz of the resin product is 30 μm or less.

3. The method for producing a resin product according to claim 1, wherein the resin product does not contain a fluorescent whitening agent.

4. The method for manufacturing a resin product according to claim 1, wherein the resin product is a blow-molded container or a tube container.

5. A resin product formed by extrusion blow molding or extrusion molding, A resin product comprising 50% by mass or more of plant-derived polyethylene and 3% by mass or more of high melt tension polypropylene relative to 100% by mass of a resin material forming the resin product.

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