JPS5861149A - Reinforced thermoplastic resin composition - Google Patents

Abstract

PURPOSE:The titled inexpensive composition exhibiting improved performances such as mechanical strength, especially impact strength and welding strength, obtained by substituting partially carbon fibers as reinforcing fibers with mineral fibers. CONSTITUTION:A reinforced resin composition comprising essentially 65-95wt% crystalline thermoplastic resin such as especially PP, polyamide, polyester, polyacetal, etc., and 5-35wt% inorganic fibers consisting of 40-90wt% carbon fibers and 10-60wt% mineral fibers. Rock wool is crushed classified into fibers and granules by an air classifying machine, etc. to give rock wool fibers having an average fiber length of 100-150mu and an average fiber diameter of 2-10mu are used as the mineral fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reinforced thermoplastic resin composition that contains inorganic fibers as a reinforcing material and 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. Inorganic fibers used for this purpose include carbon fibers, glass fibers, poron fibers, asbestos fibers, rock wool, etc. Carbon fibers have particularly excellent properties such as specific strength, specific modulus of elasticity, and electrical conductivity. It is known to exhibit good performance. In addition, thermosetting resins (carbon fiber reinforced resins containing carbon fibers as reinforcing materials) and thermosetting resins are mainly used as matrices, and the demand for them is expanding, mainly in the fields of secret aviation equipment and sports equipment. However, due to problems in molding, carbon fiber reinforced resins with a thermoplastic resin matrix are now being used more widely, especially in mechanical parts, and demand is increasing.

However, this carbon fiber is manufactured by heating organic fibers such as polyacrylonitrile fibers and pitch-based fibers to 700 to 1 soo Celsius in a nitrogen stream to carbonize them, and is therefore extremely expensive. Despite the fact that it is well recognized that it can be used in combination with skin to achieve excellent properties, it is currently not used for anything other than limited purposes.

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. The inventors discovered that by replacing some of the carbon fibers used in carbon fibers with mineral fibers, they achieved superior performance in terms of impact strength and weld strength (both of which were superior to reinforced thermoplastic resins containing only carbon fibers), and completed the present invention. This is what I did.

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, 40 to 90% by weight of the inorganic fibers being carbon fibers, and the remainder being carbon fibers. The purpose of the present invention is to provide a reinforced thermoplastic resin composition in which 10 to 60% by weight of mineral fiber is mineral fiber, and in a particularly preferred embodiment, the thermoplastic resin is polypropylene,
The present invention provides a reinforced thermoplastic resin composition that is a crystalline thermoplastic resin such as polyamide, polyester, polyacetal, polyphenylene sulfide, polyphenylene oxide, polysulfone, or the like.

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 polystyrene, styrenic polymers such as polystyrene chloride, copolymers obtained by polymerizing two or more of the above monomers, polyamides, polyethylene terephthalate Examples include polyesters such as polybutyrezoterephthalate, polyacetal, polyphenylene sulfide, polyphenylene oxide, polysulfone, and the like. These thermoplastic resins may be used alone or in combination of two or more.

Particularly preferred thermoplastic resins include polypropylene, polyamide, polyester, polyacetal, polyphenylene sulfide, polyphenylene oxide,
Crystalline thermoplastic resins such as polysulfone can be mentioned. Among these, examples of polypropylene include propylene homopolymers produced by conventionally known methods, and random copolymers or block copolymers of propylene and an α-olefin having 2 to 18 carbon atoms.

The carbon fibers used in the present invention are made from organic fibers such as polyacrylonitrile and rayon, and pitch-based fibers made from pitches such as petroleum pitch and tar pitch. It is made by heating and carbonizing, and it is also made by heating and carbonizing.
It also includes so-called graphite fibers that have been graphitized by heating to 0.degree. C., and the shape thereof is short fibers cut into lengths of 1 to 10 pieces, so-called t-hopped strands.

Furthermore, in the present invention, mineral fiber refers to rock wool (also called rock wool, slag wool, mineral wool), Ca020-45% by weight, 5i0230-50% by weight.
and Al2O35 to 20% by weight as main components, and also contains components such as MgO.

Rock wool is made by melting natural stones such as basalt and blast furnace slag produced during iron manufacturing into fibers, and has a fiber length of several meters to several meters and a particle content of about 30 to 4 inches.

Therefore, this rock wool is crushed using a rotating disc type crusher, a compression crusher, etc., and then #1! Particularly suitable is one in which the fibers and particles are classified using an air classifier or the like. Like this (=
The processed mineral fibers have an average fiber length of 100-150μ and an average fiber diameter of 2-10μ.

In the present invention, - thermoplastic resin (2) The blending amount of inorganic fibers varies depending on the type of thermoplastic resin used, but usually 65 to 95% by weight of thermoplastic resin and 7% inorganic fibers are blended. 5 to 35% by weight, preferably 70 to 90% by weight of thermoplastic resin and 10 to 35% by weight of inorganic fiber.
It is a 30-fold oath. 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 and 17 are usually 40 to 9
0% by weight is carbon fiber and the remaining 10 to 60% by weight is mineral fiber, preferably carbon fiber 60% by weight.
-85% by weight and mineral fibers 15-40% by weight. If the mineral fiber content is 60% by weight or more, it will not be possible to obtain mechanical strength that can be said to be almost the same as that of a reinforced thermoplastic resin containing only carbon fibers, and if the mineral fiber content is 10% by weight or less, there will be a significant economical It has not reached the point where it is effective.

The reinforced thermoplastic resin composition containing the thermoplastic resin, carbon fibers, and mineral fibers is prepared by a conventional method (mixing the two more uniformly (mixing the two) within the range of the above-mentioned blending ratio using an appropriate blender, etc. 2.

Further, the reinforced thermoplastic resin composition thus prepared can be molded into a desired product C by ordinary extrusion molding or injection molding.
- Molded.

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, in the preparation of the composition (1) flame retardants, pigments, plasticizers, stabilizers, antioxidants, ultraviolet absorbers, crosslinking agents, and other additives that are usually added to thermoplastic resins, A dispersant 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] 80 parts by weight of polypropylene (Tokuyama Soda ■ split product name PS-750) as a thermoplastic resin and 15 parts by weight of carbon fiber (manufactured by Mitsubishi Rayon ■, chopped strand, average fiber length a) as an inorganic fiber. Part and mineral fiber (Nippon Steel Chemical Industry ■Split product name Varnish fiber FF Average fiber diameter 4μ,
An average fiber length of 120 μm and 5 parts by weight of particles (10 μm or less, particle content: 1% or less) were mixed in a Banbury mixer to prepare a reinforced polypropylene resin composition. Regarding this reinforced polypropylene resin composition, a test piece was molded by injection molding, and the tensile strength (JIsK 6871),
Bending strength (A, STM D-790) and impact strength (A
STMD256) was measured to determine the strength of the test piece. Further, a weld test piece was molded by injection molding for this reinforced polypropylene resin composition, and the weld strength was determined in the same manner using 4 pieces, and 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, respectively, and its strength was determined. and weld strength were 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 the strength and weld strength of the test pieces 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 　　　　　　　　() represents weld strength.

As is clear from the above table (2. In the case of Example 1, the tensile strength and bending strength are almost the same as those of the comparative example, and there is a significant improvement in impact strength. Both tensile strength and bending strength (2) were improved. In addition, in the case of Example 2, there was a slight decrease in tensile strength and bending strength (=) compared to the comparative example, but they were almost the same. It can be said that a significant improvement was observed in the impact strength (-), and an improvement was observed in both the tensile strength and the bending strength in the weld strength.

As described above, according to the present invention, 40 to 90% by weight of the inorganic fibers blended into the thermoplastic resin as a reinforcing material are carbon fibers, and the remaining 10 to 60% by weight is mineral fibers. This method provides a reinforced thermoplastic resin composition that maintains mechanical strength (-) equivalent to that obtained when only carbon fiber is blended, but has improved weld strength. Since the amount of mineral fibers used can be reduced and the mineral fibers can be used, it is possible to provide a reinforced thermoplastic resin composition that is inexpensive and exhibits excellent mechanical strength.

Claims (3)

[Claims] (1) Thermoplastic resin 65-96% by weight and inorganic fiber 5-5%
35% by weight of the inorganic fibers, 40 to 90% by weight of the inorganic fibers are carbon fibers, and the remaining 10 to 60% by weight are mineral fibers. Resin composition. (2) The reinforced thermoplastic resin composition according to claim 1, wherein the thermoplastic resin is a crystalline thermoplastic resin such as polypropylene, polyamide, polyester, polyphenylene sulfide, polyphenylene oxide, or polysulfone. (3) Mineral fibers are obtained by crushing rock wool and removing the particle portion, with an average fiber length of 100 to 150μ and an average fiber diameter of 2 to 1
The reinforced thermoplastic resin composition according to claim 1, which has a bruise within the range of 0μ.