High-density polyethylene resin composition and its molded article

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a high-density polyethylene resin composition and a molded product injection-molded using the high-density polyethylene resin composition. More specifically, a high-density polyethylene resin composition obtained by blending a specific nucleating agent with a high-density polyethylene resin in a specific amount to obtain an injection-molded product having excellent low-temperature impact strength, and the high-density polyethylene resin composition. The present invention relates to a molded product having excellent low-temperature impact strength, which is injection-molded using an object.

【0002】

[Conventional technology]

Conventionally, high-density polyethylene resin has excellent low-temperature impact strength, so it is injected into the field of daily necessities such as transport containers for motorcycle parts, beer, drinking water, containers for parts storage and storage transportation, tars, buckets, snow scraping tools, etc. It is well known that molded products by the molding method are widely used.

【0003】

In recent years, even in the molding of high-density polyethylene resin by the injection molding method, the thickness of the molded product (product) has been reduced in order to shorten the molding time and pursue economic effects. Improvement of strength is required. If the melt flow rate (190 ° C, 21.18N) is less than 1g / 10 minutes high-density polyethylene resin, a molded product with sufficient low-temperature impact strength can be obtained, but the melt flow rate used in the injection molding method ( Molded products using high-density polyethylene resin with a temperature of 190 ° C, 21.18N) of 1g / 10 minutes or more have the drawback of insufficient low-temperature impact strength.

【0004】

Japanese Patent Application Laid-Open No. 1-126352 and Japanese Patent Application Laid-Open No. 8-32545 report olefin-based resin compositions containing a sorbitol-based nucleating agent. Japanese Patent Application Laid-Open No. 1-126352 improves the transparency of the polyolefin resin, the non-bleeding property and the odorlessness of the nucleating agent by using a specific sorbitol-based nucleating agent coated with a higher fatty acid. .. Although a high-density polyethylene resin is described as the olefin resin, only an example of an ethylene-propylene random copolymer is described in the examples. In addition, there is no description about impact strength here.

【0005】

Japanese Patent Application Laid-Open No. 8-32545 describes shortening of molding time of polyolefin resin, prevention of fish eye generation due to incomplete melting of nucleating agent, dimensional stability of stretched film, improvement of transparency of molded product, gloss of molded product. A composition combining a specific sorbitol-based nucleating agent is used for the purpose of improving the elastic modulus, impact resistance, and thermal deformation temperature of the molded product. A high-density polyethylene resin is also described as the olefin resin, but in the examples, only the haze value and the gloss obtained by blending the nucleating agent composition with the polypropylene resin are described, and the high-density polyethylene resin is described. No mention is made of improving impact strength.

【0006】

[Problems to be Solved by the Invention]

The present invention provides a high-density polyethylene resin composition which uses a high-density polyethylene resin as a material and can obtain an injection-molded product having excellent low-temperature impact strength, and a molded product which is injection-molded using the high-density polyethylene resin composition. The purpose is.

【0007】

[Means for solving problems]

The present inventors have studied diligently to solve the above problems. As a result, it was found that the high-density polyethylene resin composition in which a specific nucleating agent was blended in a specific amount in the high-density polyethylene resin had the desired performance, and the present invention was completed based on this finding. The present invention has the following configuration.

【0008】

(1) A high-density polyethylene resin composition in which a nucleating agent is blended in a ratio of 0.15 to 0.6 parts by weight with respect to 100 parts by weight of the high-density polyethylene resin.

【0009】

(2) Nucleating agents are 1,3,2,4-dibenzylidene sorbitol, 1,3,2,4-bis (p-methylbenzylidene) sorbitol, 1,3-p-chlorobenzylidene-2,4- p-Methylbenzylene sorbitol, 1,3,2,4-bis (p-ethylbenzylidene) sorbitol, bis (2,4,8,10-tetra-tert-butyl-6-hydroxy-12H-dibenzo [d, g] ] [1,3,2] Dioxaphosphocin-6-oxide) Aluminum hydroxide salt, sodium-bis (pt-butylphenyl) phosphate, and sodium-2,2-methylenebis (4,6-di-t) The high-density polyethylene resin composition according to the above item 1, which is one or more nucleating agents selected from the compound group consisting of -butylphenyl) phosphate.

【0010】

(3) A molded product that is injection-molded using the high-density polyethylene resin composition according to any one of the above items 1 and 2.

【0011】

BEST MODE FOR CARRYING OUT THE INVENTION

The high-density polyethylene resin used in the present invention is an ethylene homopolymer, an ethylene-propylene copolymer composed of 95% by weight or more of ethylene and 5% by weight or less of propylene (total 100% by weight), 95% by weight or more of ethylene, and 1 -An ethylene-butene copolymer consisting of 5% by weight or less of butene (100% by weight in total), with a melt florate (190 ° C, 21.18N) of 1 to 40 g / 10 minutes and a density of 0.942 to 0.965 g. /cm³belongs to. In particular, the melt flow rate (190 ° C, 21.18N) is 1 to 5 g / 10 minutes, and the density is 0.942 to 0.965 g / cm.³ High-density polyethylene resin is preferred.

【0012】

The nucleating agents used in the present invention are 1,3,2,4-dibenzylidene sorbitol, 1,3,2,4-bis (p-methylbenzylidene) sorbitol, 1,3-p-chlorobenzylidene-2, 4-p-Methylbenzylidene sorbitol, 1,3,2,4-bis (p-ethylbenzylidene) sorbitol, bis (2,4,8,10-tetra-tert-butyl-6-hydroxy-12H-dibenzo [d] , g] [1,3,2] dioxaphosphocin-6-oxide) aluminum hydroxide salt, sodium-bis (pt-butylphenyl) phosphate, and sodium-2,2-methylenebis (4,6-di) It is one or more nucleating agents selected from the compound group consisting of -t-butylphenyl) phosphate.

【0013】

The blending ratio of these nucleating agents is 0.15 to 0.6 parts by weight, preferably 0.2 to 0.4 parts by weight, based on 100 parts by weight of the high-density polyethylene resin. If the blending ratio is less than 0.15 parts by weight, the effect of improving the impact strength is insufficient, and if it exceeds 0.6 parts by weight, the effect of improving the impact strength is saturated, the economic efficiency deteriorates, and it is not practical.

【0014】

The high-density polyethylene resin composition of the present invention includes polypropylene resin, low-density polyethylene resin, linear low-density polyethylene resin, ethylene-propylene rubber, styrene-butadiene rubber, and poly, as long as the effects of the present invention are not impaired. Polymers such as vinyl acetate, ethylene-vinyl acetate copolymer and its partial saponified products; inorganic fillers such as talc, mica, glass fiber, wallastonite, zeolite, calcium carbonate, magnesium hydroxide, etc. You can do this.

【0015】

Further, in the high-density polyethylene resin composition of the present invention, various stabilizers, additives, modifiers and fine crystals usually used for polyolefins are produced, and a rigid nucleating agent exhibiting a rigidity improving effect. Etc. can be added. Examples of the stabilizer include a phosphorus-based antioxidant, a phenol-based antioxidant, and a light stabilizer, and examples of the additive include a higher fatty acid calcium, an antiblocking agent, and an antistatic agent. Examples of the modifier include radical generators and various coupling agents (silane-based, titanate-based, boron-based, and aluminate-based), and examples of the rigid nucleating agent include aluminum Pt-butylbenzoate. Can be done. These stabilizers and the like are blended in a ratio of 0.01 to 2.0 parts by weight, respectively, with respect to 100 parts by weight of the high-density polyethylene resin.

【0016】

In the high-density polyethylene resin composition of the present invention, predetermined amounts of the above-mentioned various compounding components are mixed using a normal mixing device such as a Henschel mixer (trade name), a super mixer, a ribbon blender, a tumbler mixer, and a Banbury mixer. Can be obtained by doing. The obtained mixture is pelletized at a melt-kneading temperature of 150 to 300 ° C., preferably 180 to 250 ° C. using a single-screw or twin-screw extruder or roll to obtain a pellet-like composition. You can also do it.

【0017】

The high-density polyethylene resin composition of the present invention is an injection molding method and has a molding temperature in the range of 150 to 300 ° C, preferably 180 to 260 ° C, and a mold temperature of 0 to 80 ° C, preferably 20 to 60 °. Under the molding conditions of C, motorcycle parts such as fenders; transport containers such as beer and drinking water; containers for storing and transporting parts; containers such as talls and buckets; various household appliances; industrial parts such as containers and parts cases; Daily necessities such as snow shovels, snow shavings, tool boxes, bath products, kitchen products, sanitary products; caps such as chemicals, oil, drinking water containers; ice cream containers such as shaved ice; pudding, jelly, drinking water containers It can be widely used in various fields of molded products that require low temperature impact strength.

【0018】

[Example]

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The evaluation of physical properties in Examples and Comparative Examples was performed by the following method.

【0019】

1) Melt flow rate of high-density polyethylene resin: Compliant with JIS K 6760 (190 ° C, 21.18N).

【0020】

2) Izod impact strength (23 ° C): Complies with the impact test method specified in JIS K7110 (Unit: KJ / m)²). Using pellets granulated at a melt-kneading temperature of 230 ° C in a nitrogen atmosphere using a single-screw extruder, the primary injection pressure is 1000 kg / cm.²The test piece, which was injection-molded under the molding conditions of a mold temperature of 50 ° C and a cycle time of 25 seconds, was allowed to stand in a constant temperature room at 23 ± 2 ° C for 48 hours, and then conformed to the impact test method specified in JIS K7110. To measure.

【0021】

3) Izod impact strength (-30 ° C): Complies with the impact test method specified in JIS K7110 (Unit: KJ / m)²). Using pellets granulated at a melt-kneading temperature of 230 ° C in a nitrogen atmosphere using a single-screw extruder, the primary injection pressure is 1000 kg / cm.², The test piece injection-molded under the molding conditions of mold temperature 50 ° C and cycle time 25 seconds was allowed to stand in a constant temperature room at 23 ± 2 ° C for 48 hours, and then -30 ° C using methyl alcohol as a refrigerant. After allowing to stand in a constant temperature bath for 30 minutes to cool, measure according to the impact test method specified in JIS K7110.

【0022】

Examples 1-33 Each of the various nucleating agents, phenolic antioxidants, and higher fatty acid calcium (neutralizing agent) listed in each of the tables below is blended into the high-density polyethylene resin in the proportions shown in Tables 1 to 5 below. , Phenol mixer (trade name) for 2 minutes, and the obtained mixture was extruded at a melt-kneading temperature of 230 ° C. using a single-screw extruder having a diameter of 40 mm and pelletized into pellets. Using the pellets obtained in each of the examples, a predetermined test piece was prepared, and the Izod impact strength was evaluated by the above evaluation method. The results are shown in Tables 1 to 5 described later.

【0023】

Comparative Examples 1 to 7 Phenolic antioxidants and neutralizers are mixed with various high-density polyethylene resins in the proportions shown in Table 6 below, mixed according to Examples 1-33, pelletized, and pelletized. Obtained. Using the pellets obtained in each of the comparative examples, a predetermined test piece was prepared, and the Izod impact strength was evaluated by the above evaluation method. The results are shown in Table 6 below.

【0024】

The relationship between the various polyethylene resins and compounding agents used in Examples and Comparative Examples and the abbreviations used in the table is shown in the lower part of Tables 1 and 2. The blending amount is a part by weight with respect to 100 parts by weight of the high-density polyethylene resin.

【0025】

[table 1]

<img file="JP2001192513A_D0001.tif" />【0026】

[Table 2]

<img file="JP2001192513A_D0002.tif" />【0027】

[Table 3]

<img file="JP2001192513A_D0003.tif" />【0028】

[Table 4]

<img file="JP2001192513A_D0004.tif" />【0029】

[Table 5]

<img file="JP2001192513A_D0005.tif" />【0030】

[Table 6]

<img file="JP2001192513A_D0006.tif" />【0031】

[Effect of the invention]

The high-density polyethylene resin composition of the present invention is a composition in which a specific amount of a nucleating agent is blended with the high-density polyethylene resin, and by using the composition, an injection-molded product having excellent low-temperature impact strength can be obtained. Can be fenders and other motorcycle parts; beer, drinking water and other transport containers; parts storage or storage and transport containers; tars, buckets and other containers; various household appliances; containers, parts cases and other industrial parts; snow shovels , Snow warp, tool box, bath supplies, kitchen supplies, sanitary supplies and other daily necessities; chemicals, oil, drinking water containers and other caps; ice cream, shaved ice and other ice cream containers; pudding, jelly, drinking water and other food products It can be widely and suitably used for molded products in various fields that require low-temperature impact strength, such as containers.