Molded articles comprising reinforcement fibers and a thermoplastic resin are lightweight and have excellent mechanical properties, and thus have been widely used, for example, in sports applications, aerospace applications, and general industrial applications. Examples of such reinforcement fibers include metal fibers such as aluminum fibers and stainless fibers, inorganic fibers such as silicon carbide fibers and carbon fibers, organic fibers such as aramid fibers and poly p-phenylene benzoxazole (PBO) fibers, and the like. Among these, carbon fibers are suitable in terms of the balance between specific strength, specific rigidity and lightness; and in particular, polyacrylonitrile-based carbon fibers are suitably used.
The mechanical properties of a carbon fiber reinforced thermoplastic resin molded article can be enhanced, for example, by increasing the content of carbon fibers, but an increased content of carbon fibers tends to result in uneven distribution of the carbon fibers in the carbon fiber reinforced thermoplastic resin molded article, often causing a reduction in impact strength. Thus, alternatively, the mechanical properties of a carbon fiber reinforced thermoplastic resin molded article can be enhanced, for example, by adding organic fibers having flexibility and high elongation at break in addition to the carbon fibers.
As a long-fiber reinforced composite resin composition having a high mechanical strength and provided with conductivity, a long-fiber reinforced composite resin composition comprising an olefin resin, organic long fibers, and carbon fibers is disclosed (see, for example, JP 2009-114332 A). Further, as a fiber reinforced plastic excellent in impact resistance, a fiber reinforced plastic composed of reinforcement fibers and a thermoplastic resin is proposed, wherein the reinforcement fibers are composed of carbon fibers and heat-resistant organic fibers (see, for example, JP 2014-62143 A). In addition, as a fiber reinforced thermoplastic resin molded article excellent in impact strength and low-temperature impact strength, a fiber reinforced thermoplastic resin molded article including carbon fibers, organic fibers and a thermoplastic resin is proposed, wherein the carbon fibers and the organic fibers each have an average fiber length within a specific range, and the average straight-line distance between two edges of a single fiber and the average fiber length of the carbon fibers and the organic fibers are in a specific relationship (see, for example, WO 2014/098103).
However, a molded article obtained using the technique disclosed in JP 2009-114332 A or JP 2014-62143 A has an improved impact strength but yet has a problem of deteriorating a surface appearance of molded article by adding organic fibers. Further, although the technique disclosed in WO 2014/098103 permits production of a molded article with a significantly improved impact strength and an improved surface appearance by adjusting fiber length to the specific range. However, a further improvement in surface appearance along with maintaining impact strength of members and parts is expected with expanding various applications in recent years.
It could therefore be helpful to provide a fiber reinforced thermoplastic resin molded article excellent in impact strength and surface appearance.
USPTO Backgrounds
USPTO Backgrounds