JPH0115526B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a polyolefin resin composition used for industrial materials, particularly automobile bumpers, instrument panels, various trims, and various housings for light electrical equipment. [Prior Art] Polyolefin composite materials are widely used mainly in the automobile and light electrical fields. In recent years, as the field of use has expanded, the various performances required have become extremely sophisticated. And while increasing the conflicting physical properties of impact strength and rigidity, we also achieved flow marks,
A good appearance without welded appearance or silver streaks is required. In the prior art, various methods have been proposed to satisfy these requirements, such as the following. A method for specifying the particle size of talc (Special Publication Act 1983
3417, Publication No. 60-3413). Products that use a combination of rubbery substances and talc (JP-A-Sho
53-64257, 55-34271, 58-17139). Those using calcium carbonate with a specific particle size (Japanese Patent Application Laid-open Nos. 55-120643 and 56-120742). Those using grafted polypropylene (Japanese Unexamined Patent Publication Nos. 57-125234 and 58-83043). Those using a combination of calcium carbonate and talc or calcium carbonate and glass fiber (Unexamined Japanese Patent Publication No. 1983-
145746, Publication No. 59-100149). However, although these methods have shown some improvement, they are still not sufficient, and on the contrary, the following drawbacks occur. Since talc is used, flow marks occur and the weld appearance is poor. Although impact strength is improved, the effect of improving rigidity is low. In this case, the improvement effect on both impact strength and rigidity is small. If there is a lot of talc, flow marks and weld appearance will be bad, and if there is a lot of calcium carbonate, the effect of improving rigidity will be small. Furthermore, since glass fibers have long fiber lengths, surface roughness is likely to occur, resulting in significantly poor dimensional stability and reduced impact strength. [Problems to be Solved by the Invention] The present invention aims to provide a polyolefin resin composition that has high impact and rigidity, and has a good appearance (flow marks, welds, silver streaks). [Means for Solving the Problems] One aspect of the present invention solves the above problems by blending polyolefin with a mixed inorganic filler consisting of a fibrous reinforcing agent, talc, and calcium carbonate in a predetermined shape and in a predetermined ratio. It is resolved. Polyolefins used in the present invention include polyethylene, polypropylene, polybutene-1,
Polymethylpentene-1 and mixtures thereof are used. Preferably, polyethylene, polypropylene, polybutene-1 and mixtures thereof are used. High-density polyethylene as polyethylene,
Medium or low density polyethylene or linear low density polyethylene is used, preferably one having an MI of 3 to 50 g/10 min. There are no particular restrictions on the polypropylene, but the following polypropylene polymers containing an ethylene component are preferred. Ethylene-propylene random copolymer. A copolymer composition consisting of an ethylene-propylene random copolymer and homopolypropylene (commercially available as a so-called propylene-ethylene block copolymer). A composition of the above or with a propylene homopolymer. Among these polypropylenes, those having an MI of 2 to 70 g/10 min are preferred. The mixture of polyethylene and polypropylene is preferably a mixture consisting of 5 to 30% by weight of polyethylene and 95 to 70% by weight of the above copolymer composition. The mixed inorganic filler of the present invention has an A fiber diameter of 0.1 to 2μ.
A fibrous reinforcing agent selected from fibrous magnesium oxysulfate, gypsum fiber, magnesium hydroxide fiber, and magnesium oxide fiber, B: talc with an average particle size of 0.3 to 3μ, and C: an average particle size of 0.1 to 1.0μ. It is made of calcium carbonate. Even if a fibrous reinforcing agent made of another material is used as the fibrous reinforcing agent A, a product that is satisfactory in terms of appearance and strength cannot be obtained. If a fiber diameter of less than 0.1μ is used, the effect of improving rigidity cannot be obtained, and if a fiber diameter of more than 2μ is used, the appearance will be poor. If talc (B) has an average particle size of less than 0.3μ, it will result in poor dispersion and lower impact strength.
Even if it is blended with a material exceeding 3μ, the impact strength will decrease. If the calcium carbonate (C) has an average particle size of less than 0.1 μm, it will result in poor dispersion and the impact strength will decrease, and if it has an average particle size of more than 1.0 μm, the impact strength will decrease. The polyolefin resin composition of the present invention contains 50 to 99% by weight, preferably 60 to 95% by weight, of the polyolefin and 50 to 1% by weight, preferably 40 to 5% by weight of the mixed inorganic filler. 50% mixed inorganic filler
If the amount exceeds the weight percentage, poor moldability, decreased flowability, and decreased impact strength will occur, and the specific gravity will increase, causing practical problems. Furthermore, if it is less than 1% by weight, the effect of improving rigidity and impact strength is small. Here, when the blending amounts of A, B, and C are respectively a part by weight, part b, and part by weight, a/a+b+c≧0.2 b<a<3c. That is, when a/a+b+c<0.2, the rigidity tends to decrease, when b≧a, the appearance deteriorates, and when a≧3c, the impact strength tends to decrease. Another invention of the present invention is a polyolefin resin composition using a polyolefin resin containing less than 50% by weight of a thermoplastic elastomer, which is a mixture of a polyolefin and a thermoplastic elastomer, instead of the polyolefin. The type and blending ratio of the mixed inorganic filler to be blended therein are the same as those described above. Impact strength is improved by incorporating a thermoplastic elastomer into a polyolefin. If the blending amount of the thermoplastic elastomer in the polyolefin is 50% by weight or more, the rigidity will be significantly lowered and the moldability will be lowered. The thermoplastic elastomers used in the present invention include ethylene propylene rubber, ethylene propylene diene rubber, styrene-ethylene-butadiene-styrene rubber (S-E-B-S), and styrene-butadiene-styrene rubber (S-B-S). ), styrene-isoprene-styrene rubber (S-I-
S), styrene-butadiene rubber (S-B), etc., with ethylene propylene rubber, ethylene propylene diene rubber, and styrene butadiene rubber being preferred. In addition, other resins such as nylon, polycarbonate, acrylonitrile-styrene-butadiene resin, polystyrene, polyvinyl chloride, polyphenylene oxide, ethylene-
Other thermoplastic resins such as vinyl acetate copolymers can be blended. Furthermore, in the present invention, in addition to the above components,
Adding commonly used additives such as antioxidants, ultraviolet absorbers, antistatic agents, lubricants, pigments, nucleating agents, dispersants, coupling agents, plasticizers, etc. and other organic or inorganic additives as appropriate. Can be done. In producing the composition of the present invention, each component may be blended in a predetermined amount and sufficiently kneaded by a combined dry blending/melting blending method, a multistage melt blending method, a simple melt blending method, or the like. The kneading can be carried out using a Banbury mixer, a co-kneader, an extruder, a twin-screw extruder, etc., and is carried out at a temperature of 180°C or higher, preferably 210°C or higher.
There are no particular restrictions on the addition and mixing order of each component during mixing and melt mixing. When manufacturing a molded article from the composition of the present invention,
Various molding methods such as injection molding, extrusion molding, blow molding, compression molding, lamination molding, roll processing, stretching processing, and stamp processing can be applied. [Examples] The present invention will be explained below with reference to Examples, but the scope of the present invention is not limited to these Examples. Predetermined amounts of polyolefin, mixed inorganic filler, and thermoplastic elastomer shown in the table were blended and pelletized using an extruder. Also, 140 for external measurement.
A square plate with a grid measuring mm x 140 mm x 3 mm was made by injection molding. Using the obtained pellets, test pieces were prepared using an injection molding machine, and various physical properties were measured. The results are shown in the table. Izotsu impact strength Conforms to ASTM-D-256 Falling weight impact strength Conforms to JIS K 7211 Receiver 50φ, striking center 1/4 inch R, load 2Kg Bending strength Conforms to ASTM-D-790 Flexural modulus Conforms to ASTM-D-790 Compliant appearance Visually observed

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〔Effect of the invention〕

The polyolefin resin composition of the present invention has improved rigidity and impact strength compared to conventional compositions, while also producing molded products with excellent appearance, and its industrial effects are extremely large.

Claims (1)

[Scope of Claims] 1. A polyolefin resin composition comprising 50 to 99% by weight of polyolefin and 50 to 1% by weight of the following mixed inorganic fillers A, B and C. A is a fibrous reinforcing agent with a fiber diameter of 0.1 to 2μ and selected from fibrous magnesium oxysulfate, gypsum fiber, magnesium hydroxide fiber, and magnesium oxide fiber, and B is a fibrous reinforcing agent with an average particle diameter of 0.3 to 3μ.
Talc and C are calcium carbonate with an average particle size of 0.1 to 1.0μ, and A, B, and C are respectively a parts by weight, b parts by weight, and c.
When expressed as parts by weight, the following relationships are satisfied: a/a+b+c≧0.2 and b<a<3c. 2. The polyolefin resin composition according to claim 1, wherein the polyolefin is polyethylene, polypropylene, or a mixture thereof. 3 50-99% by weight polyolefin resin which is a mixture of polyolefin and thermoplastic elastomer and contains less than 50% by weight thermoplastic elastomer
and the following mixed inorganic fillers A, B and C50~1
A polyolefin resin composition consisting of % by weight. A is a fibrous reinforcing agent with a fiber diameter of 0.1 to 2μ and selected from fibrous magnesium oxysulfate, gypsum fiber, magnesium hydroxide fiber, and magnesium oxide fiber, and B is a fibrous reinforcing agent with an average particle diameter of 0.3 to 3μ.
Talc and C are calcium carbonate with an average particle size of 0.1 to 1.0μ, and A, B, and C are respectively a parts by weight, b parts by weight, and c.
When expressed as parts by weight, the following relationships are satisfied: a/a+b+c≧0.2 and b<a<3c. 4. The polyolefin resin composition according to claim 3, wherein the polyolefin is polyethylene, polypropylene, or a mixture thereof. 5. The polyolefin resin composition according to claim 3 or 4, wherein the thermoplastic elastomer is ethylene propylene rubber, ethylene propylene diene rubber, or styrene butadiene rubber.