Polyethylene foam

Abstract

To provide a polyethylene foam capable of reducing an environmental load.SOLUTION: The polyethylene foam of the present invention contains recycled polyethylene, plant-derived polyethylene, and petroleum-derived polyethylene.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to polyethylene foams. [Background technology]

[0002] BACKGROUND ART Polyethylene foam made from petroleum-derived polyethylene has been used for packaging containers and the like (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-289494 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in recent years, concerns about global warming due to an increase in carbon dioxide in the atmosphere and the depletion of fossil fuel resources have led to calls for petroleum products to have a reduced environmental impact.

[0005] Therefore, an object of the present invention is to provide a polyethylene foam that can reduce the environmental load. [Means for solving the problem]

[0006] In order to achieve the above object, the polyethylene foam of the present invention comprises: This includes recycled polyethylene, plant-derived polyethylene, and petroleum-derived polyethylene. [Effects of the Invention]

[0007] The polyethylene foam of the present invention contains recycled polyethylene and plant-derived polyethylene in addition to petroleum-derived polyethylene, thereby reducing the environmental load. DETAILED DESCRIPTION OF THE INVENTION

[0008] The polyethylene foam of the present invention contains recycled polyethylene, plant-derived polyethylene, and petroleum-derived polyethylene. The polyethylene foam may be composed of only the recycled polyethylene, the plant-derived polyethylene, and the petroleum-derived polyethylene, or may further contain other components (for example, fillers (including colorants such as pigments)).

[0009] The recycled polyethylene may include post-industrial waste resin, post-consumer resin, reground polymer resin, and combinations thereof. The recycled polyethylene may be prepared in-house or may be commercially available. Commercially available products are available from, for example, Tobu Kogyo Co., Ltd.

[0010] The amount of recycled polyethylene in the total amount of the polyethylene foam is not particularly limited, and is, for example, 50 parts by weight or more. If the amount is 50 parts by weight or more, the foam can obtain Eco Mark certification from the Japan Environment Association, a public interest incorporated foundation.

[0011] The plant-derived polyethylene may be, for example, a commercially available product manufactured by Braskem, such as "SEB853," "SHC7260," "SHD7255LSL," "SLH218," or "SLL118." One type of plant-derived polyethylene may be used alone, or two or more types may be used in combination.

[0012] The amount of the plant-derived polyethylene in the total amount of the polyethylene foam is not particularly limited, and is, for example, 25 parts by weight or more. If the amount is 25 parts by weight or more, it is possible to obtain permission to use the Biomass Pla (BP) mark from the Japan Bioplastics Association.

[0013] The petroleum-derived polyethylene may be one that has been conventionally used in polyethylene foams, such as the Novatec LD series manufactured by Japan Polyethylene Co., Ltd., the MIRASON series manufactured by Mitsui Dow Polychemicals Co., Ltd., and the Suntech series manufactured by Asahi Kasei Corp. One type of petroleum-derived polyethylene may be used alone, or two or more types may be used in combination.

[0014] The blending amount of the petroleum-derived polyethylene in the total amount of the polyethylene foam may be, for example, the remainder of the other components.

[0015] The polyethylene foam can be obtained by, for example, the following method, but is not limited to this method.

[0016] First, the recycled polyethylene, the plant-derived polyethylene, the petroleum-derived polyethylene, a foaming agent, a crosslinking agent, and, if necessary, a foaming aid, a lubricant, a filler, etc. are kneaded using a heated mixing roll, a pressure kneader, an extruder, etc. to obtain a compound.

[0017] Examples of the foaming agent include azo compounds such as azodicarbonamide and barium azodicarboxylate; nitroso compounds such as dinitrosopentamethylenetetramine and trinitrotrimethyltriamine; hydrazide compounds such as p,p'-oxybisbenzenesulfonylhydrazide; and sulfonylsemicarbazide compounds such as p,p'-oxybisbenzenesulfonylsemicarbazide and toluenesulfonylsemicarbazide.

[0018] Examples of the crosslinking agent include organic peroxides such as ketone peroxide, dialkyl peroxide, hydroperoxide, peroxyester, peroxymonocarbonate, diacyl peroxide, peroxycarbonate, peroxyketal, and dicumyl peroxide.

[0019] The foaming aid may be appropriately selected depending on the type of foaming agent, and examples thereof include compounds containing urea as a main component; metal oxides such as zinc oxide and lead oxide; and compounds containing salicylic acid, stearic acid, or the like as a main component.

[0020] Examples of the lubricant include compounds containing stearic acid as a main component.

[0021] Examples of the filler include metal oxides such as zinc oxide, titanium oxide, calcium oxide, magnesium oxide, and silicon oxide; carbonates such as magnesium carbonate and calcium carbonate; fibrous materials such as pulp; various dyes, pigments, and fluorescent materials; and rubber compounding agents.

[0022] Next, the compound is filled into a mold and subjected to a pressure of 20 kgf / cm 2 (20×0.098MPa)~150kgf / cm 2 The mixture is heated in a sealed container under pressure (150×0.098 MPa) at 140° C. to 170° C. for 40 to 80 minutes. During this pressurizing and heating process, the foaming agent and the crosslinking agent are partially decomposed.

[0023] Next, the mold is opened to obtain an intermediate foam.

[0024] Next, the intermediate foam is placed in the center of a non-airtight, openable metal mold with a flow path for heated steam around the periphery, and heated to 150°C to 170°C under normal pressure to decompose the remaining foaming agent and crosslinking agent, and then cooled to obtain the polyethylene foam.

[0025] The polyethylene foam can be widely used in a variety of applications where polyethylene foam has conventionally been used, such as packaging containers. [Example]

[0026] Using the compound having the composition shown in Table 1, polyethylene foams of Example 1 and Reference Examples 1 to 3 were obtained using the method exemplified in the above-mentioned detailed description of the invention.

[0027] The apparent density, tensile strength, elongation, compression stress at 10%, compression stress at 20%, compression stress at 50%, 25% compression set (after 30 minutes), 25% compression set (after 24 hours), and thermal stability of the polyethylene foams of Example 1 and Reference Examples 1 to 3, measured in accordance with JIS K 6767, are shown in Table 1.

[0028] [Table 1]

[0029] As shown in Table 1, in Example 1, physical properties comparable to those of Reference Example 1, which used only petroleum-derived polyethylene, Reference Example 2, which used plant-derived polyethylene and petroleum-derived polyethylene, and Reference Example 3, which used recycled polyethylene and petroleum-derived polyethylene were obtained, confirming that it is possible to realize a polyethylene foam that contains recycled polyethylene, plant-derived polyethylene, and petroleum-derived polyethylene and that can reduce the environmental impact.

[0030] Although the present invention has been described above with reference to the embodiments and examples, the present invention is not limited to the above-described embodiments and examples. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

Claims

1. A polyethylene foam comprising recycled polyethylene, plant-derived polyethylene, and petroleum-derived polyethylene.

2. The polyethylene foam according to claim 1, wherein the amount of recycled polyethylene blended is 50 parts by weight or more.

3. The polyethylene foam according to claim 1 or 2, wherein the blending amount of the plant-derived polyethylene is 25 parts by weight or more.

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