JPS607658B2 - Polypropylene resin composition for molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polypropylene resin composition for molding, and more particularly to a resin composition containing a large amount of iron sand and having excellent moldability.

Conventionally, compositions in which fillers such as metals and high-density inorganic substances are blended with polyolefin have been developed, but no examples of using iron sand as a filler have been known at all.

In other words, even if a large amount of iron sand is blended into polyolefin as a filler, it is difficult to form the composition into pellets, and when forming pellets, there is significant abrasion and damage to the machinery, and furthermore, moldability is poor. Therefore, it could not be put to practical use. Therefore, the present inventors conducted intensive research to develop a polyolefin resin composition that contains a large amount of iron sand, has good moldability, and has excellent mechanical strength. They discovered that the objective could be achieved by blending a certain proportion of iron sand having a particle size within a specific range, and completed the present invention.

That is, the present invention provides isotactic polypropylene 2
The present invention provides a molding polypropylene resin composition comprising at least 2% by weight of atactic polypropylene and 80-95% by weight of iron sand having a particle size of 50-200 mesh. The isotactic polypropylene used in the present invention is a crystalline polypropylene polymer produced by polymerization using a typical Ziegler catalyst, and has a melt index of 1.0 to 15.0, particularly 6 to 12. The one that is the best. Further, it is necessary that the amount of isotactic polypropylene blended is 2% by weight or more based on the total composition. In other words, if the blending amount of isotactic polypropylene is less than 2% by weight or is not included, the molded product will lack rigidity during injection molding of the composition, resulting in poor moldability from the mold, resulting in deformation or It is undesirable that it may be damaged. The atactic polypropylene used in the present invention is an amorphous polypropylene polymer created during the production of the above-mentioned isotactic polypropylene, and preferably has an average molecular weight of 10,000 to 50,000.

Appropriate blending of the atactic polypropylene improves the kneading properties, moldability, especially injection moldability of the composition, and also increases the blending amount of iron sand, which has the advantage of providing a material with high specific gravity and low cost. has. The amount of atactic polypropylene blended for this purpose is preferably 2% by weight or more based on the total composition. Furthermore, the iron sand used in the present invention refers to alluvial deposits whose main constituent minerals are sandite, titanite, hematite, and limonite, among which the average grain size is 50 to 200 mesh, and the iron content is 50.
~6% by weight of natural or artificially prepared iron sand is preferably used.

In other words, it is difficult to increase the blending amount of iron sand with a particle size larger than 50 mesh, and causes damage due to abrasion of the Z mixer and molding machine, and iron sand smaller than 200 mesh reduces the flow of the composition. It is undesirable because it significantly reduces the performance. In addition, the above-mentioned iron sand accounts for 80 to 95% of the total composition.
Blend in weight percent. Even when the iron sand content is small, the Z obtained from the composition has little meaning in using iron sand as a filler, and addition of more than 95% by weight makes it difficult to mold the composition. In the present invention, if necessary, a suitable amount of metal soap such as barium stearate, calcium stearate, etc. can be added as a boar agent.

The composition of the present invention can be manufactured, molded, and processed by conventional methods. For example, the above-mentioned isotactic polypropylene, atactic polypropylene, iron sand, and a thickener are mixed in a predetermined proportion using an intermixer, Banbury, etc. A molded article can be obtained by thoroughly blending and kneading the ingredients using a kneader such as a mixer, then forming pellets, and then extruding, injection or compression molding the pellets using a molding machine.

According to the present invention, the polypropylene resin composition hardly causes wear and tear of a machine such as a beletizer when it is made into a pellet, and has good moldability, especially injection moldability.

Moreover, the obtained molded product has a glossy appearance and does not generate flow marks. Furthermore, the molded product has the characteristic that by adjusting the blending ratio of polypropylene and iron sand, various products with textures ranging from soft to hard can be obtained. Therefore, the polypropylene resin composition of the present invention can be effectively and widely used for marine materials such as fishing gear, toys, etc., and also as a raw material for condensate.

Next, examples of the present invention will be shown.

Examples Isotactic polypropylene (melt index 7.0), atactic polypropylene (intrinsic viscosity 0.45 in 135o0 tetralin solution, specific gravity 0.8)
7) and iron sand (iron content 51%) with 100% passing through 60 mesh and 98% remaining on 150 mesh were kneaded in a predetermined ratio using an intermixer, and then pelletized.

Using this, injection moldability, finished appearance, and performance of the molded product were investigated. The results are shown in Table 1. Table 1 Comparative Example In the example, the same operations as in the example were performed except that the blending ratio of each raw material was outside the range of the present invention.

The results are shown in Table-2. Table-2

Claims (1)

[Claims] 1 Isotactic polypropylene 2% by weight or more, atactic polypropylene 2% by weight or more and particle size 50
A polypropylene resin composition for molding comprising 80 to 95% by weight of iron sand of ~200 mesh.