JPH06271722A - Resin composition for injection molding - Google Patents

Abstract

PURPOSE:To provide the subject composition which can give a molding excellent in rigidity and impact resistance. CONSTITUTION:This resin composition comprises 100 pts.wt. polypropylene resin and 5-100 pts.wt. inorganic filler comprising 2-50wt.% whiskers having an average fiber length of 10-300mum and an aspect ratio of 15-80 and 50-98wt.% talc having a mean particle diameter of 3-15mum.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition for injection molding.

[0002]

2. Description of the Related Art Conventional containers, such as containers and pallets, have been designed on the assumption that they will be carried by a person, so that they should not be damaged by a malfunction such as a drop or a collision, and the performance required for that purpose. Was only impact resistant.

However, with the recent popularization of industrial robots, the size and weight of luggage that can be carried at one time increases,
Along with this, the transportation container has become larger and heavier, and therefore, the transportation container has been required to have excellent rigidity.

For the purpose of improving the rigidity, for example, a resin composition in which an inorganic filler is added to a polypropylene resin is generally used, but the transport container obtained from these resin compositions has an improved rigidity. However, since the impact resistance is lowered, in JP-B-1-24815, a polypropylene resin is used as an injection molding resin composition capable of obtaining a transport container excellent in rigidity and impact resistance.
It has been proposed that the whiskers have a short diameter having an average fiber diameter of 0.1 to 2 μm and talc have a small particle diameter having an average particle diameter of 0.3 to 3 μm. However, the rigidity of the transportation container molded using the above resin composition has not been sufficient yet.

[0005]

SUMMARY OF THE INVENTION In view of the above drawbacks, an object of the present invention is to provide a resin composition for injection molding, which enables to obtain a molded article excellent in rigidity and impact resistance.

[0006]

The polypropylene resin used in the present invention is a resin mainly composed of polypropylene. Examples of the polypropylene-based resin include propylene homopolymer and ethylene-propylene copolymer. When the ethylene content in the ethylene-propylene copolymer is low, the impact resistance of the obtained molded article is low, and when it is high, the rigidity of the obtained molded article is low. , And more preferably 1 to 7% by weight.

When the melt flow rate (MFR) of the above polypropylene resin is small, the fluidity of the resin is low and the moldability is low, and when it is high, the dispersibility of the talc to be added is low and the obtained molded product is Since the rigidity decreases,
1 to 50 g / 10 minutes is preferable, and 2-1 is more preferable.
It is 5 g / 10 minutes.

The inorganic filler used in the present invention is
It consists of whiskers and talc. The average fiber length of the whiskers is 10 to 300 μm because the shorter the rigidity of the obtained molded article is, the longer the whisker has, the lower the dispersibility of the whiskers in the resin and the lower the impact resistance of the resulting molded article.
Limited to m.

When the aspect ratio of the whisker is small, the rigidity of the obtained molded article is low, and when it is large, the dispersibility of the whisker in the resin is low and the impact resistance of the obtained molded article is low. Limited to 80.

Examples of the whiskers include wollastonite, gypsum fiber, PMF (Processed Mineral Fiber).
r), xonotlite and the like. When the content of the above whiskers decreases, the rigidity of the obtained molded product decreases, and when the content of the whiskers increases, the moldability of the resin decreases.
Limited to ~ 50% by weight.

The average particle size of the above talc is 3 to 15 μm, since the dispersibility of the talc in the resin decreases and the rigidity of the obtained molded product decreases as the average particle size increases or decreases.
Limited to When the content of the above talc decreases, the rigidity of the obtained molded article decreases, and when the content of the talc increases, the impact resistance of the obtained molded article decreases.
Limited to wt%.

The above whiskers and talc may be used as they are without treatment, but for the purpose of improving the dispersibility, for example, titanate or silane coupling agents, saturated or unsaturated fatty acids, vinyl-based non-functional compounds are used. It may be used after being coated with a carboxylic acid having a saturated bond, a fatty acid metal salt, a fatty acid ester, a fatty acid amide or the like. The coating treatment may be performed in advance before kneading the resin composition, or may be performed at the time of kneading the resin composition.

When the amount of the above-mentioned inorganic filler added is small, the rigidity of the obtained molded article is low, and when it is large, the impact resistance of the obtained molded article is low. Therefore, it is 5 to 100 parts by weight of the polypropylene resin. It is limited to 100 parts by weight, preferably 10 to 70 parts by weight. In addition to whiskers and talc, the inorganic filler may contain, for example, calcium carbonate, mica, carbon fiber, boron fiber, silica, etc. within a range that does not impair the physical properties of the obtained molded product. .

In addition to the above-mentioned inorganic filler, rubber such as ethylene-propylene copolymer rubber is added to the resin composition for injection molding of the present invention within a range that does not impair the physical properties of the obtained molded product. May be. The composition of the resin composition for injection molding of the present invention is as described above, but within a range that does not impair the physical properties of the obtained molded product, a lubricant, an antioxidant, an antistatic agent, an ultraviolet absorber, a flame retardant, a release agent. A mold agent, a coloring agent, etc. may be added.

The resin composition for injection molding of the present invention melts a polypropylene resin and an inorganic filler by, for example, a single screw extruder, a twin screw extruder, a Banbury mixer, a roll, a Brabender, a plastograph, a kneader and the like. , Obtained by kneading.

[0016]

EXAMPLES Next, examples of the present invention will be described. In addition, "part" below means "part by weight". Example 1 (1) Production of pellets As a polypropylene resin, ethylene content is 4.1.
% By weight, melt florate (MFR) 7.0 g
As a whisker, 100 parts of an ethylene-propylene copolymer (“MS640” manufactured by Tokuyama Soda Co., Ltd.) having a length of / 10 minutes, a wollastonite having an average fiber length of 200 μm and an aspect ratio of 30 (“FUWALIP” manufactured by Kansai Gravel Co., Ltd.). ))
As 20 parts and talc, 20 parts of talc having an average particle size of 3.5 μm (“K-1” manufactured by Nippon Talc Co., Ltd.), and
0.1 part of a hindered phenolic antioxidant (“CYANOX1790” manufactured by Ciba-Geigy) and a sulfur-based antioxidant (“SEENOX412S” manufactured by Cypro Kasei) 0.
Two parts were supplied to a twin-screw extruder (“PCM87” manufactured by Ikegai Tekko Co., Ltd.) and extruded at a temperature of 220 ° C. and a screw rotation speed of 150 rpm to obtain a resin sheet, and the obtained resin sheet was pelletized to obtain pellets.

(2) Manufacture of container The obtained pellets are injected into a molding machine (T85 manufactured by Toshiba Machine Co., Ltd.).
-M2 ”), injection molding at a temperature of 40 ° C. and a mold clamping pressure of 850 t, and a length of 592 mm, a width of 384 mm, and a height of 20.
A container with a size of 0 mm was obtained.

Examples 2 to 9 and Comparative Examples 1 to 9 Except that the predetermined amounts (parts) of ethylene-propylene copolymer, inorganic filler and ethylene-propylene copolymer rubber shown in Tables 1 and 2 were used. A container was obtained in the same manner as in Example 1.

[0019]

[Table 1]

[0020]

[Table 2]

Using the containers obtained in Examples 1 to 9 and Comparative Examples 1 to 9, a bottom surface deflection measurement test was conducted to evaluate rigidity, and a drop test was conducted to evaluate impact resistance. The obtained results are shown in Tables 3 and 4. In the bottom surface deflection measurement test, the container is placed on two rails having a width of 100 mm, which are installed in parallel at an interval of 270 mm, with the long sides of the bottom surface parallel to the rail, and then placed on the bottom surface of the container. Apply a load of 50 kg evenly at a temperature of 50 ° C,
This state was maintained for 2 weeks at a humidity of 50%, and the deflection (mm) of the central portion of the bottom surface of the container was measured.

The drop test was carried out in accordance with JIS Z 0602. That is, the container was dropped from a height of 2 m onto a concrete floor so that the container would land from the bottom or a corner, and the case where the container was not broken was marked with ◯, and the case where it was broken was marked with x. In addition, if the container was cracked or cracked even a little, it was considered as destruction.

[0023]

[Table 3]

[0024]

[Table 4]

[0025]

Since the constitution of the resin composition for injection molding of the present invention is as described above, a molded article excellent in rigidity and impact resistance can be obtained by using the resin composition for injection molding.

Claims (1)

[Claims] 1. A polypropylene-based resin, 100 parts by weight;
5 to 100 parts by weight of an inorganic filler composed of 2 to 50% by weight of whiskers having an average fiber length of 10 to 300 μm and an aspect ratio of 15 to 80 and 50 to 98% by weight of talc having an average particle size of 3 to 15 μm. A resin composition for injection molding, comprising: