JPH022414B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a method for manufacturing fiber-reinforced plastic molded articles by cold working or warm working. Prior Art Generally, thermoplastic resins are molded by melt molding methods such as extrusion molding and injection molding, but they can also be molded by plastic processing (cold processing) such as rolling and rolling. This molding method using plastic working has advantages such as a simple molding device, molding in a short time, and molecular rearrangement occurring during the molding process, which improves the mechanical strength of the molded product. On the other hand, if the force applied during molding is too large, the material will break, and if the molded product is at the temperature during molding or at a temperature above the glass transition temperature, the shape will return to the state before plastic deformation. In particular, when fillers or reinforcing fibers are included, the ductility decreases, resulting in a decrease in plastic workability. Furthermore, even if plastic deformation is possible, the material may partially break and its strength decreases. Therefore, it is necessary to heat the resin to around its melting point before molding, which makes the process complicated and requires high-temperature energy. OBJECT OF THE INVENTION An object of the present invention is to provide a method for producing a plastic molded article that can be easily plastically deformed over a wide temperature range from low to high temperatures. Another object of the present invention is to provide a method for manufacturing fiber-reinforced plastic molded articles having excellent strength, heat resistance, and creep properties. Summary of the Invention The present invention proposes that by adding a relatively low molecular weight compound with a molecular weight of 3000 or less to a thermoplastic resin containing reinforcing fibers, the ductility of the thermoplastic resin can be increased, and the shape of the resin even when reinforcing fibers are contained. Furthermore, if the compound with a molecular weight of 3,000 or less has unsaturated bonds, it can be polymerized by irradiating it with radiation to form a crosslinked structure, thereby causing plastic deformation. It was completed based on the inventor's knowledge that deformation can be fixed. Therefore, the method for producing a fiber-reinforced plastic molded article of the present invention consists of (1) a thermoplastic resin and an average number of aliphatic unsaturated bonds in the molecule;
A step of kneading a composition containing an unsaturated compound having a ratio of 1.05 or more and a molecular weight of 3000 or more and reinforcing fibers to obtain a kneaded product; (2) After molding the kneaded product, the temperature is below the melting point of the composition. (3) a step of irradiating the molded product with radiation;
This achieves the above objective. The thermoplastic resin contained in the composition used in the present invention is a linear polymer compound. These include, for example, nylon 6, nylon 66, and nylon 12 (all trade names) that have amide bonds in their main chains; saturated polyester resins such as polybutylene terephthalate (PBT) and polyethylene terephthalate (PET); polyacetal resins; polycarbonate There is resin. These belong to engineering plastics. In addition, vinyl chloride, polypropylene, etc. may also be used. The unsaturated compound contained in the above composition has a molecular weight of 3000 or less, preferably 1500 or less. If the molecular weight exceeds 3000, compatibility with thermoplastic resins is poor. This unsaturated compound has a carbon-carbon double bond at the molecular end or side chain. For that,
For example, there are compounds in which a group represented by the following formula is bonded to the end of the molecule: -C=CH ₂ ,

[Formula] -O-CH ₂ -CH=CH ₂ In the formula, R is hydrogen or an alkyl group. The number of double bonds in the molecule is on average 1.05 or more, preferably
1.5 or higher. If it is less than 1.05, linear polymerization will occur, but a sufficient crosslinked structure will not be formed, making it impossible to obtain a resin with excellent heat resistance and creep properties. This unsaturated compound is 1 to 45 parts by weight per 100 parts by weight of the thermoplastic resin.
It is contained in an amount of 5 to 30 parts by weight, preferably 5 to 30 parts by weight. 1
If it is less than 45 parts by weight, the intended purpose will not be achieved, and if it is more than 45 parts by weight, the shape of the molded product will not be stable. The reinforcing fibers contained in the above composition include glass fibers, carbon fibers, and aramid fibers.
The reinforcing fibers are contained in an amount of 5 to 65 parts by weight based on 100 parts of the total weight of the thermoplastic resin and unsaturated compound. The above-mentioned composition is kneaded with a filler added thereto as required, using a commonly used kneading machine such as an extruder or an injection molding machine at a temperature equal to or higher than the melting point of the composition. The resulting kneaded product is molded and then plastically deformed into a desired shape at a temperature below the melting point of the composition. Plastic deformation is performed by commonly used methods such as rolling, rolling, cold pressing, and plastic extrusion. The resulting plastically deformed product is subjected to radiation irradiation. Unsaturated compounds polymerize due to radiation irradiation. As the radiation, alpha rays, gamma rays, ultraviolet rays, electron beams, etc. are used. Gamma radiation and electron beams are preferably used. When irradiating with radiation, a sensitizer may be added to promote polymerization. Instead of irradiating with radiation, heat may be applied to the extent that the fibers do not deteriorate. Examples The present invention will be described below with reference to examples. Example 1 100 parts by weight of polyethylene terephthalate (PET; EFG-6 manufactured by Kanebuchi Chemical Co., Ltd.), an unsaturated compound having the following structure in which methacrylic acid was added to the molecular terminal of bisphenol type epoxide (average number of unsaturated groups
A composition containing 20 parts by weight (2.0; molecular weight 512), 120 parts by weight of glass fiber, and 1 part by weight of a thermal polymerization inhibitor was charged into an extruder, kneaded at 265°C, and extruded into a round bar with a diameter of 9 mm: This round bar was rolled at room temperature to obtain an M10 type screw.
This screw was irradiated with an electron beam of 10 Mrad. One M10-type iron nut was placed on each end of each screw before and after electron beam irradiation, and the maximum load (tensile strength of the screw) that could be withstood when the nut was pulled in opposite directions was measured. Table 1 shows the average values for each five screws. Five other screws were left standing in an atmosphere at 150° C. for 1 hour, and changes in shape were observed. Furthermore, five other screws were left standing in an atmosphere at 260° C. for 1 hour, and changes in shape were observed. Each of the above screws was soaked in a phenol-methylene chloride mixture (1:1) at 80°C.
The amount of insoluble matter was measured after 5 hours of immersion, and the presence or absence of crosslinking of the resin was examined. The results are shown in Table 1. Comparative Example 1 100 parts by weight of PET (same as in Example 1) and 100 parts by weight of glass fiber were charged into an extruder, and a screw was manufactured in the same manner as in Example 1. The tensile strength of the screw after electron beam irradiation and the shape stability at various temperatures as in Example 1 were examined. Table 1 shows the results.
Shown below.

[Table] Example 2 Using the same composition as in Example 1, a flat plate with a thickness of 3 mm was obtained using an extruder. This flat plate was rolled to a thickness of 2 mm at room temperature and irradiated with an electron beam of 10 Mrad.
Each flat plate was subjected to a bending test before and after the electron beam irradiation, and the shape stability at various temperatures and the presence or absence of crosslinking were examined in the same manner as in Example 1. The results are shown in Table 2. Comparative Example 2 The same formulation as in Comparative Example 1 was charged into an extruder to obtain a flat plate with a thickness of 3 mm. This flat plate was subjected to a bending test and its shape stability in an atmosphere of 150°C was investigated.
The results are shown in Table 2.

[Table] Effects of the Invention According to the method of the present invention, since the composition used contains an unsaturated compound with a relatively small molecular weight, even if it contains reinforcing fibers, the ductility of the resin decreases. After molding, the kneaded product can be molded in a short time using a simple molding device at a temperature below the melting point of the composition, and the mechanical strength of the molded product can be increased due to molecular rearrangement during the molding process. It can contribute to improvement. By irradiating the plastically deformed product with radiation, the unsaturated compounds can be polymerized to form a crosslinked structure, so that plastic deformation can be fixed. As a result, the molded product has excellent strength, heat resistance, and creep properties.

Claims (1)

[Claims] 1 (1) A thermoplastic resin having an average ratio of 1.05 or more aliphatic unsaturated bonds in its molecules and a molecular weight of
A step of kneading a composition containing an unsaturated compound of 3000 or less and reinforcing fibers to obtain a kneaded product; (2) A step of molding the kneaded product and then plastically deforming and molding it at a temperature below the melting point of the composition; and (3) a step of irradiating the molded article with radiation. A method for producing a fiber-reinforced plastic molded article. 2. The composition contains the unsaturated compound in a proportion of 1 to 45 parts by weight based on 100 parts by weight of the thermoplastic resin, and the reinforcing fiber has a total weight of 100 parts by weight of the unsaturated compound and the thermoplastic resin. The manufacturing method according to claim 1, wherein the content is 5 to 65 parts by weight.