JPH05295190A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE:To provide the objective compsn. having a high heat distortion temp. and improved bending modulus, impact strength, and gloss by compounding a specific PP resin with a BaSO4 powder and a nucleating agent. CONSTITUTION:100 pts.wt. PP resin comprising 60-95wt.% propylene homopolymer having a melt flow rate (JIS K 7210, 230 deg.C, 2.16kgf-load) of 1-30g/10min, a number-average mol.wt. of 10,000-50,000, and a density of 0.88-0.92g/cm<3> and 5-40wt.% ethylene-propylene block copolymer having a melt flow rate of 1-30g/10min and a number-average mol.wt. of 10,000-100,000 is compounded with 10-50 pts.wt. BaSO4 powder having a mean particle size of 0.04-0.7mum and 0.1-3 pts.wt. nucleating agent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene resin composition.

[0002]

2. Description of the Related Art Polypropylene resin has a flexural modulus,
Since it has excellent mechanical strength such as impact resistance and heat resistance, it is used in various molded products. However, as the size of a molded product becomes larger, higher flexural modulus and impact resistance are required, and a molded product used outdoors requires a high heat distortion temperature. In order to solve these problems, JP-A-1-
Japanese Patent No. 129052 describes adding talc, mica, glass fiber and the like to a polypropylene resin.

[0003]

However, a molded product obtained from a polypropylene resin composition to which talc, mica, etc. are added has a higher flexural modulus than a molded product obtained from a polypropylene resin alone. However, the impact resistance and glossiness are deteriorated. Further, the molded product obtained from the polypropylene resin composition to which the glass fiber is added has an improved heat distortion temperature, but the glossiness of the surface is lowered, and it is large in rain gutters, automobile parts, etc. It could not be used for molded products requiring surface gloss.

The object of the present invention is to solve the above-mentioned problems and to obtain a molded article which is excellent in mechanical strength such as flexural modulus and impact resistance, has a high heat deformation temperature and is excellent in surface property.
A polypropylene resin composition is provided.

[0005]

The polypropylene resin used in the present invention comprises a propylene homopolymer and an ethylene propylene block copolymer. When the melt flow rate of the propylene homopolymer becomes small, molding becomes difficult, and when it becomes large, not only the dispersion of the barium sulfate powder becomes poor, but also when obtaining a molded product by injection molding, burrs occur at the time of molding and extrusion molding. Therefore, when a molded product is obtained, problems such as difficulty in taking out the extruded kneaded product occur. Therefore, JIS K 7
230 ° C measured according to 210, 2.16 kgf
Melt flow rate under 1 to 30g / 1
0 minutes is preferred. The number average molecular weight of the propylene homopolymer is 10,000 in order to obtain a molded product having a high flexural modulus.
~ 50,000 is preferred. The propylene homopolymer is preferably crystalline and has a density of 0.88 to 0.92 g / cm ³ . When the amorphous propylene homopolymer is added, the impact strength of the obtained molded article increases, but the elastic modulus of the molded article decreases, so the addition amount of the amorphous propylene homopolymer is 30% in the polypropylene resin. It is preferably not more than wt%. The number average molecular weight of the amorphous propylene homopolymer is 1,000 to
50,000 is preferred. The density of the amorphous propylene homopolymer is preferably 0.85 to 0.87 g / cm ³ .

In the above ethylene propylene block copolymer, the impact strength of the molded product decreases as the ethylene content decreases, and the elastic modulus of the molded product decreases as the ethylene content increases. Therefore, the ethylene content depends on the ethylene propylene block copolymer. It is preferably 5 to 30% by weight in the combined product. When the melt flow rate of the ethylene propylene block copolymer becomes low, molding becomes difficult, and when it becomes high, not only the dispersion of the barium sulfate powder becomes poor, but also burrs are generated at the time of molding when obtaining a molded article by injection molding, When a molded product is obtained by extrusion molding, problems such as difficulty in collecting the extruded kneaded product occur. Therefore, JIS K 72
Melt flow rate under a load of 2.16 kgf at 230 ° C. measured in accordance with 10 is 1 to 30 g / 10
Minutes are preferred. The number average molecular weight of the ethylene propylene block copolymer is preferably 10,000 to 100,000.

When the amount of the ethylene propylene block copolymer added is small, the impact strength of the molded product becomes low,
Since the flexural modulus of the molded product decreases as the amount increases, it is limited to 5 to 40% by weight, preferably 10 to 30% by weight in the polypropylene resin.

When the average particle size of the barium sulfate powder used in the present invention is small, the particles aggregate during molding and the dispersibility is poor, and the impact strength of the resulting molded article is low, and when it is large, the resulting molded article is Since the flexural modulus decreases, it is limited to 0.04 to 0.7 μm, preferably 0.1 to 0.6 μm.

If the amount of barium sulfate powder added is small, the flexural modulus of the resulting molded article will be low, and if it is too large, the impact strength of the molded article will be low. Therefore, 10 to 50 parts by weight relative to 100 parts by weight of the polypropylene resin. And is preferably 20 to 40 parts by weight.

The nucleating agent used in the present invention is not particularly limited as long as it is a substance which becomes a nucleus of the polypropylene resin crystals and is effective in growing the crystals, and examples thereof include dibenzylidene sorbitol, adipic acid and benzoic acid. Examples include sodium acidate. Further, a crosslinked polypropylene resin obtained by irradiating the polypropylene resin itself with a high energy electron beam may be used. These may be used alone or in combination of two or more kinds.

When the amount of the nucleating agent added is small, the crystallization of the polypropylene resin does not proceed during molding and the flexural modulus of the resulting molded article is low, and when it is large, the impact strength of the resulting molded article is low. So, polypropylene-based resin 10
It is limited to 0.1 to 3 parts by weight, preferably 0.2 to 1 part by weight, relative to 0 parts by weight.

In the present invention, the impact resistance, heat distortion temperature, heat flowability of the composition, etc. of the molded product obtained as required are not impaired, and the resistance of polyisobutylene, etc., which has been conventionally used, is improved. Impact modifier, calcium carbonate, calcium carbonate, calcium silicate, talc, mica, clay, magnesium carbonate, alumina, silica, calcium sulfate, silica sand, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, zeolite, graphite, hydroxide Inorganic fillers such as calcium, calcium sulfite, quartz, bentonite, asbestos, carbon fiber, metal whiskers, glass fiber, glass beads, glass powder, glass flakes, styrene-butadiene rubber, 1,2-polybutadiene, butyl rubber, styrene- Butadiene / styrene block copolymer, Nitrile-butadiene rubber,
Polyisobutylene, polybutadiene, polyisoprene,
Copolymer of α-olefin other than ethylene and polypropylene, homopolymer of α-olefin other than polypropylene, copolymer of α-olefins other than polypropylene, ethylene / vinyl acetate copolymer, maleic anhydride grafted polyethylene Α-olefin-based graft polymer such as polyamide, polycarbonate, acrylonitrile butadiene styrene resin, polyvinyl chloride, thermoplastic resin such as polyphenylene ether, antioxidant, lubricant, colorant, ultraviolet absorber, antistatic agent, A dispersant, a neutralizing agent, a plasticizer, a foaming agent, a flame retardant, a crosslinking agent, etc. may be added.

The method for producing the polypropylene resin composition of the present invention is not particularly limited, and any conventionally known method may be employed. For example, propylene homopolymer, ethylene propylene block copolymer, barium sulfate powder. And the nucleating agent can be obtained by kneading with a usual kneading machine such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll, a Brabender platograph, a kneader or a plastomill.

The method for obtaining a molded product from the polypropylene resin composition of the present invention is not particularly limited, and any conventionally known method can be adopted, for example, extrusion molding method, injection molding method, blow molding method, A compression molding method, a vacuum molding method or the like is used.

[0015]

EXAMPLES Details of the present invention will be described with reference to examples. Examples 1 to 3 and Comparative Examples 1 to 5 Predetermined amount of crystalline polypropylene homopolymer (trade name; MA2A, manufactured by Mitsubishi Yuka Co., Ltd., melt flow rate 25 g / 10 minutes, number average molecular weight 30, 000, density 0.90 g / cm ³ ), amorphous polypropylene homopolymer (manufactured by Eastman Chemical Co., trade name; M-5H, melt flow rate 15 g / 10 minutes, number average molecular weight 4,40).
0, density 0.85 g / cm ³ ), ethylene propylene vilock copolymer (manufactured by Mitsubishi Petrochemical Co., Ltd., trade name; BC8, ethylene content 9% by weight, number average molecular weight 57,000, melt flow rate 1.8 g / 10 minutes), polyethylene (made by Asahi Kasei, trade name; Suntec M1820), barium sulfate powder 1 (average particle size 0.6 μm), barium sulfate powder 2
(Average particle size 0.8 μm), barium sulfate powder 3 (average particle size 0.06 μm), talc (manufactured by Sobueclay, trade name; Mistron Vapor: average particle size 3 μm) and dibenzylidene sorbitol plastomill (Toyo Seimitsu Co., Ltd.) Made)
And kneaded for 5 minutes to obtain a polypropylene resin composition.
The composition obtained is heated at a temperature of 210 ° C. under a pressure of 1
Molded at 50 kg / cm ³ , 150 mm × 150 mm ×
A 3.2 mm molded body was obtained.

The flexural modulus, Izod impact strength, heat distortion temperature and glossiness of the molded product thus obtained were measured by the following methods, and the results are shown in Table 2.

Flexural Modulus The obtained molded body was cut into a length of 120 mm and a width of 12.7.
mm, thickness 3.2 mm test piece was obtained, ASTM D-7
According to 90, the flexural modulus was measured.

Izod impact strength The obtained molded body was cut, and the central portion had a radius of curvature of 0.25 m.
65 mm long, 12.7 mm wide, with m notches
A test piece having a thickness of 3.2 mm was obtained, and the Izod impact strength was measured according to ASTM D-256.

Heat Deformation Temperature A test piece was obtained by cutting the obtained molded body, and JIS K 7
According to 207, the heat distortion temperature was measured with a load of 4.6 kg / cm ² .

Glossiness The obtained molded product was cut to obtain a test piece, and JIS K 7
According to 105, the glossiness was measured at an incident angle of 60 ° and a reflection angle of 60 °.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

As described above, the polypropylene resin composition of the present invention comprises a polypropylene resin composed of a polypropylene homopolymer and an ethylene propylene block copolymer, barium sulfate powder having a specific average particle diameter, and a nucleating agent. Therefore, it is possible to obtain a molded article having excellent flexural modulus, impact strength and heat distortion temperature and high gloss.

Therefore, the obtained molded product is suitably used for large-sized molded products such as rain gutters and automobile members.

Claims (1)

[Claims] 1. Propylene homopolymer 60 to 95% by weight
100 parts by weight of a polypropylene resin composed of 5 to 40% by weight of ethylene propylene block copolymer and barium sulfate powder 10 to 5 having an average particle diameter of 0.04 to 0.7 μm.
A polypropylene resin composition comprising 0 parts by weight and 0.1 to 3 parts by weight of a nucleating agent.