Method for producing molded article
To provide a production method with which a molded article excelling in surface appearance can be produced. The method for producing a molded article containing a thermoplastic resin and reinforcing fibers having a number-average fiber length of 1 mm or longer, wherein the method includes molding a material containing a thermoplastic resin and reinforcing fibers having a number-average fiber length of less than 30 mm using a first closed mold, and then molding only the molded material once again using a second closed mold.
1. A method for producing a molded article, the molded article comprising a thermoplastic resin and reinforcing fibers having a number-average fiber length of 1 mm or longer, the method comprising:
molding in a first closed mold a material containing the thermoplastic resin and reinforcing fibers having a number-average fiber length of less than 30 mm;
after molding with the first closed mold, removing only the molded article molded in the first closed mold from the first closed mold;
applying only the molded article molded from the first closed mold to a second closed mold which is a different mold than the first closed molded; and
then molding only the molded material once again in the second closed mold;
wherein a shape of the second closed mold is identical to a shape of the first closed mold.
2. The method for producing a molded article according to claim 1 , wherein a shape of the second closed mold differs from a shape of the first closed mold.
3. The method for producing a molded article according to claim 2 , wherein a material temperature when the material is applied to the second closed mold is from 0.1 to 7° C. lower than a material temperature when the material is applied to the first closed mold.
4. The method for producing a molded article according to claim 3 , wherein a difference between a mold temperature when molding is performed using the first closed mold and a material temperature when the material is applied to the second closed mold is from 20 to 320° C.
5. The method for producing a molded article according to claim 2 , wherein a difference between a mold temperature when molding is performed using the first closed mold and a material temperature when the material is applied to the second closed mold is from 20 to 320° C.
6. The method for producing a molded article according to claim 1 , wherein a material temperature when the material is applied to the second closed mold is from 0.1 to 20° C. lower than a material temperature when the material is applied to the first closed mold.
7. The method for producing a molded article according to claim 1 , wherein a difference between a mold temperature when molding is performed using the first closed mold and a material temperature when the material is applied to the second closed mold is from 30 to 340° C.
8. The method for producing a molded article according to claim 1 , wherein the material is heated and then applied to the first closed mold.
9. The method for producing a molded article according to claim 8 , wherein the material is applied to the first closed mold by injection molding.
10. The method for producing a molded article according to claim 1 , wherein the material is a UD tape cut to a length of less than 30 mm, and the cut UD tape is applied to the first closed mold.
11. The method for producing a molded article according to claim 1 , wherein the thermoplastic resin comprises a polyamide resin.
12. The method for producing a molded article according to claim 1 , wherein the thermoplastic resin comprises a polyamide resin constituted from diamine-derived constituent units and dicarboxylic acid-derived constituent units; and 50 mol % or more of the diamine-derived constituent units are derived from xylylenediamine, and 50 mol % or more of the dicarboxylic acid-derived constituent units are derived from an α,ω-linear aliphatic dicarboxylic acid having from 4 to 20 carbons.
13. The method for producing a molded article according to claim 1 , wherein the thermoplastic resin comprises a polyolefin resin.
14. The method for producing a molded article according to claim 1 , wherein the reinforcing fibers include at least one type selected from the group consisting of glass fibers and carbon fibers.
15. The method for producing a molded article according to claim 1 , wherein the number-average fiber length of the reinforcing fibers having a number average fiber length of less than 30 mm and included in the material is from 10 to 25 mm.
16. The method for producing a molded article according to claim 1 , wherein the number-average fiber length of the reinforcing fibers having a number-average fiber length of 1 mm or longer and included in the molded article is 1 mm or longer and less than 30 mm.
17. The method for producing a molded article according to claim 1 , wherein the number-average fiber length of the reinforcing fibers having a number-average fiber length of 1 mm or longer and included in the molded article is 10 mm or longer and less than 30 mm.
18. The method for producing a molded article according to claim 1 , wherein a mold temperature when molding is performed using the second closed mold is from 0.1 to 7° C. lower than the mold temperature when molding is performed using the first closed mold.
19. The method for producing a molded article according to claim 1 , wherein the material is heated and then applied to the second closed mold.