JPH0140061B2 - - Google Patents

Description

[Detailed description of the invention]

This invention includes inorganic fiber as a reinforcing material,
This invention relates to a reinforced thermoplastic resin composition that exhibits excellent mechanical strength. BACKGROUND ART Conventionally, it has been widely practiced to blend inorganic fibers into thermosetting or thermoplastic resins in a predetermined proportion to improve their properties such as mechanical strength, heat resistance, and dimensional stability. Examples of inorganic fibers used for this purpose include carbon fiber, glass fiber, boron fiber, asbestos fiber, and rock wool.
It is known to exhibit excellent performance in properties such as conductivity. In addition, carbon fiber-reinforced resins containing carbon fiber as a reinforcing material are mainly used as a matrix of thermosetting resins, and the demand for them is expanding, mainly in the fields of aerospace equipment and sports equipment. However, due to molding problems, carbon fiber reinforced resins with thermoplastic resin matrices are now being used more widely, especially in mechanical parts, and demand is increasing. However, this carbon fiber is extremely expensive because it is produced by carbonizing organic fibers such as polyacrylonitrile fibers and pitch fibers by heating them to 700 to 1800°C in a nitrogen stream.
Despite the fact that it is well recognized that it can be blended into resins to exhibit excellent properties, it is currently not used for anything other than limited uses. In view of this point of view, the present inventors have conducted intensive research on reinforced thermoplastic resin compositions that are inexpensive and exhibit excellent mechanical strength, and have surprisingly found that The inventors discovered that by replacing some of the carbon fibers in carbon fibers with certain mineral fibers, they achieved better performance in terms of impact strength and weld strength than reinforced thermoplastic resins containing only carbon fibers, and thus completed the present invention. It is something. That is, the present invention is a composition mainly consisting of 65 to 95% by weight of a thermoplastic resin and 5 to 35% by weight of inorganic fibers, of which 40 to 90% by weight is carbon having a fiber length of 1 to 10 mm. The remaining 10~
A reinforced thermoplastic resin composition in which 60% by weight is mineral fiber with an average fiber length of 100 to 150μ and an average fiber diameter of 2 to 10μ, obtained by crushing rock wool and removing its particle portion, is provided. Particularly preferred embodiments provide reinforced thermoplastic resin compositions in which the thermoplastic resin is a crystalline thermoplastic resin such as polypropylene, polyamide, polyester, polyacetal, polyphenylene sulfide, polyphenylene oxide, polysulfone, etc. It is. In the present invention, thermoplastic resins include polymers of hydrocarbon compounds such as polyethylene and polypropylene, polymers of halogenated hydrocarbon compounds such as polyvinyl chloride and polyvinylidene fluoride, and unsaturated resins such as polyvinyl alcohol and polyvinyl ether. Polymers of alcohols or ethers, polymers of unsaturated carboxylic acids or their esters such as polymethyl acrylate, polymethyl methacrylate, and polyvinyl acetate, polymers of unsaturated nitriles such as polyacrylonitrile, polyvinylamine, polyacrylamide Polymers of unsaturated amines or amides such as, styrenic polymers such as polystyrene, polystyrene chloride, etc.
Alternatively, copolymers obtained by polymerizing two or more of the above monomers, polyamides, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetals, polyphenylene sulfides, polyphenylene oxides, polysulfones, etc. can be mentioned. These thermoplastic resins may be used alone or in combination of two or more. Particularly preferred thermoplastic resins include crystalline thermoplastic resins such as polypropylene, polyamide, polyester, polyacetal, polyphenylene sulfide, polyphenylene oxide, and polysulfone. Examples of polypropylene include propylene homopolymers produced by conventionally known methods, and random copolymers or block copolymers of propylene and α-olefin having 2 to 18 carbon atoms. Furthermore, the carbon fibers used in the present invention are organic fibers such as polyacrylonitrile and rayon, and pitch fibers made from pitches such as petroleum pitch and tar pitch, and heated at 700 to 1800°C in a nitrogen stream.
It is made by heating and carbonizing, and
It also includes so-called graphite fibers, which are graphitized by heating to 2500 to 2700℃, and their shape is 1 to 10 mm in length.
These are short fibers that have been cut into strands, so-called chopped strands. Furthermore, in the present invention, the mineral fiber refers to rock wool (also called rock wool, slag wool, mineral wool), and contains 20 to 45% by weight of CaO and 30 to 30% by weight _{of SiO2} .
The main components are 50% by weight and 5-20% by weight of Al ₂ O ₃ ,
It also contains other components such as MgO.
Rotsuk wool is a fiber made by melting natural stones such as basalt and blast furnace slag, which is a by-product during iron manufacturing, with a fiber length of several mm to several cm and a particle content of 30 to 40.
%, but in the present invention, this rock wool is crushed using a rotary disk crusher, a compression crusher, etc., and then the fibers and particles are classified using an air classifier, etc. to be used. The mineral fibers processed in this way have an average fiber length of 100~150μ and an average fiber diameter of 2~
It is within the range of 10μ. In the present invention, the amount of inorganic fiber blended into the thermoplastic resin varies depending on the type of thermoplastic resin used, but usually the thermoplastic resin
95% by weight, 5 to 35% by weight of inorganic fibers, preferably 70 to 90% by weight of thermoplastic resin and 10 to 30% by weight of inorganic fibers. If the amount of inorganic fiber exceeds 35% by weight, the molded product will become brittle, and if it is less than 5% by weight, the reinforcing effect of the inorganic fiber will be insufficient. In addition, the composition of the above inorganic fiber is usually 40
~90% by weight is carbon fiber and the remaining 10-60% by weight is mineral fiber, preferably 60-85% by weight carbon fiber and 15-40% by weight mineral fiber. If the mineral fiber content is 60% by weight or more, it will not be possible to obtain mechanical strength that is almost equivalent to that of a reinforced thermoplastic resin containing only carbon fibers, and
If it is less than 10% by weight, no significant economic effect will be achieved. The reinforced thermoplastic resin composition containing the above-mentioned thermoplastic resin, carbon fibers, and mineral fibers is prepared by uniformly mixing them within the range of the above-mentioned blending ratios using an appropriate blender or the like using a conventional method. Ru. Further, the reinforced thermoplastic resin composition thus prepared is molded into a desired product by conventional extrusion molding or injection molding. Note that the surfaces of the carbon fibers and mineral fibers may be treated with a treatment agent that improves adhesion to the thermoplastic resin. In addition, when preparing the composition, flame retardants, pigments, plasticizers, stabilizers, antioxidants, ultraviolet absorbers, crosslinking agents, and other additives that are usually added to thermoplastic resins,
A dispersing agent or the like used when blending inorganic fibers as a reinforcing material may be added. Hereinafter, the present invention will be specifically explained based on Examples and Comparative Examples. Example 1 Polypropylene (Tokuyama Soda Co., Ltd.) was used as a thermoplastic resin.
Co., Ltd. product name PS-750), 15 parts by weight of carbon fiber (manufactured by Mitsubishi Rayon Co., Ltd., chopped strand, average fiber length 3 mm) as an inorganic fiber, and mineral fiber (Nippon Steel Chemical Product name S-Fiber manufactured by Kogyo Co., Ltd.
FF average fiber diameter 4μ, average fiber length 120μ, particles (10μ
(Content: 1% or less) and 5 parts by weight were mixed in a Banbury mixer to prepare a reinforced polypropylene resin composition. This reinforced polypropylene resin composition was molded into test pieces by injection molding, and the tensile strength (JISK6871), bending strength (ASTM D-790), and impact strength (ASTM
D256) was measured to determine the strength of the test piece. Also,
This reinforced polypropylene resin composition was molded into a weld test piece by injection molding, and the weld strength was determined in the same manner. The results are shown in the table. Example 2 A test piece was formed in the same manner as in Example 1 by blending 80 parts by weight, 10 parts by weight, and 10 parts by weight of the polypropylene, carbon fiber, and mineral fiber used in Example 1 above, and its strength and weldability were determined. The strength was determined. The results are shown in the table. Comparative Example 80 parts by weight and 20 parts by weight of the polypropylene and carbon fiber used in each of the above Examples were mixed, test pieces were molded in the same manner as in each Example, and their strength and weld strength were determined. The results are shown in the table. Note that the numerical values of the above examples are expressed in comparison with the comparative example being set as 100.

[Table] As is clear from the table above, in the case of Example 1, the tensile strength and bending strength were almost the same as those of the comparative example, and there was a significant improvement in impact strength. Both tensile strength and bending strength were improved. In addition, in the case of Example 2, although there is a slight decrease in tensile strength and bending strength compared to the comparative example, it can be said that they are almost the same, and a significant improvement in impact strength is observed. Furthermore, improvements in both tensile strength and bending strength were observed in the weld strength. As described above, according to the present invention, among the inorganic fibers blended into the thermoplastic resin as a reinforcing material,
40 to 90% by weight is carbon fiber with a fiber length of 1 to 10 mm,
By making the remaining 10 to 60% by weight of the specified mineral fiber, that is, mineral fiber with an average fiber length of 100 to 150μ and an average fiber diameter of 2 to 10μ, which are obtained by crushing rock wool and removing the particle portion. This provides a reinforced thermoplastic resin composition that maintains the same mechanical strength as when only carbon fiber is blended, but has even better weld strength, reducing the amount of expensive carbon fiber used. Since the amount of mineral fibers can be reduced and cheaper mineral fibers can be used, it is possible to provide a reinforced thermoplastic resin composition that is inexpensive and exhibits excellent mechanical strength.

Claims (1)

[Claims] 1. 65 to 95% by weight of thermoplastic resin and 5 to 95% by weight of inorganic fibers.
Of the above inorganic fibers, 40-90% by weight are carbon fibers with a fiber length of 1-10 mm, and the remaining 10-60% by weight is made from crushed rock wool. 1. A reinforced thermoplastic resin composition comprising mineral fibers having an average fiber length of 100 to 150 μm and an average fiber diameter of 2 to 10 μm after particle portions are removed. 2 The thermoplastic resin is polypropylene, polyamide, polyester, polyphenylene sulfide,
The reinforced thermoplastic resin composition according to claim 1, which is a crystalline thermoplastic resin such as polyphenylene oxide or polysulfone.