JPH0140854B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polypropylene composition reinforced with short glass fibers, and more particularly to a reinforced polypropylene composition with improved falling ball impact resistance characterized by incorporating short glass fibers with an extremely small diameter. Traditionally, short glass fibers (hereinafter referred to as GF) have been added to polypropylene in order to improve its physical properties, and various proposals have been made to improve the properties of polypropylene, such as modification of polypropylene and surface treatment of GF. is being done. However, although GF-reinforced polyolefin compositions can provide excellent tensile strength, rigidity, dimensional stability, etc., improvements in falling ball impact resistance are generally insufficient. Adding a rubber-like substance to polypropylene or using a copolymer of ethylene and propylene may be considered in order to improve resistance to falling ball impact, but this would result in a decrease in rigidity. When GF is added to improve rigidity, the falling ball impact resistance decreases, making it difficult to obtain a composition with well-balanced physical properties. As a result of intensive research to improve the physical properties of GF-reinforced polypropylene compositions, the present inventors found that by blending extremely thin GF and modified polypropylene in place of the conventionally used GF with a diameter of approximately 13μ, the present inventors achieved increased rigidity and falling ball impact resistance. The present invention was completed by discovering that it is possible to improve the following in a well-balanced manner. In the present invention, the polypropylene is an ethylene propylene copolymer containing propylene as a main component, or a copolymer obtained by adding ethylene propylene rubber, and the ethylene component content is 5 to 5.
20wt% is preferably used. The modified polypropylene blended into polypropylene in the present invention to improve its affinity with GF is
Publication No. 27422 or Polymer Chemistry Vol.25, No.174,
It is a product obtained by graft polymerizing an unsaturated carboxylic acid or its acid anhydride to polypropylene, as disclosed in p107. The blending amount of such modified polypropylene is 5 to 5% based on the obtained composition.
30wt% is preferred. If it is less than 5wt%, the improvement in tensile strength and rigidity will not be sufficient, and if it exceeds 30wt%, the effect of improving physical properties will not increase and it will be economically disadvantageous. The GF used in the present invention has a diameter of 3 microns or less, preferably 2.5 microns or less, more preferably a maximum diameter of 3 microns or less and an average diameter of 1 micron or less. It is effective to subject GF to surface treatment with a coupling agent to improve its adhesion to polypropylene and cutting treatment to homogeneously disperse it in polypropylene in order to improve its physical properties. The amount of GF added to the polypropylene is preferably 5 to 40 wt% based on the resulting composition. If it is less than 5wt%, the improvement in tensile strength and rigidity is not sufficient, and if it is less than 40wt%,
%, uniform kneading becomes difficult and falling ball impact resistance decreases, both of which are unfavorable. The present invention will be further explained below with reference to Examples and Comparative Examples. The method for measuring the physical property values and the sample preparation method are as follows. Izotsu impact strength: JIS K7110 (notched) Flexural modulus: JIS K7203 Tensile strength: JIS K7113 Falling ball impact strength: Using a Dupont impact tester manufactured by Toyo Seiki, 1.50 inch inner diameter, 50 specimens
The 50% fracture energy was measured at mm x 50 mm x 2 mm and a test temperature of -20°C. GF surface treatment: By mixing the GF mass impregnated with 0.2 wt% water and an alcoholic solution of γ-aminoproptriethoxysilane equivalent to 0.5 wt% of the glass fiber using a Henschel mixer. , GF grinding, solvent evaporation and surface treatment were performed. GF without surface treatment was only ground. The fiber lengths after pulverization were all within the range of 0.1 to 1.0 mm. Mixing: Predetermined amount of polypropylene, modified polypropylene (polypropylene grafted with 2wt% maleic anhydride), EPR, and
After premixing GF with a blender, it was kneaded and granulated using a single screw extruder. Test piece: Each test piece was produced by injection molding according to the above test method. The materials used, their blending ratios, and their physical properties are listed in Table 1.

【table】

[Table] As is clear from the data shown in Table 1, when the ethylene propylene copolymer is blended with ordinary GF, the falling ball impact resistance decreases significantly (Comparative Examples 2, 7 to 9). When GF is blended, the degree of this decrease can be greatly reduced (Examples 1 to 3). Furthermore, it has been shown that surface treatment of GF with a coupling agent and mixing of EPR with polypropylene can further improve the falling ball impact resistance. For reference, polyamide (nylon 6, nylon 66), polycarbonate and ABS (acrylonitrile/butadiene/styrene resin) are usually
Table 2 shows the changes in physical properties when GF was added. The Izotsu impact strength is determined by the GF composition.
It improves with amorphous resins and decreases with crystalline resins. On the other hand, the falling ball impact strength was significantly reduced for all resins as in Comparative Example 2 and Comparative Examples 7 to 9, and the compositions of each example using ultra-fine GF showed no such reduction. is prevented.

【table】

【table】

Claims (1)

[Claims] 1 Ethylene-propylene copolymer whose main component is propylene, or a product obtained by adding ethylene propylene rubber to the copolymer, and polypropylene 90 to 90% with an ethylene component content of 5 to 20 wt%.
50 wt%, modified polypropylene 5-30 wt%, and ultra-fine short glass fibers with a diameter of 3 microns or less
40wt% (total 100wt%).