| 摘要 |
PROBLEM TO BE SOLVED: To provide a plastic ball having a high sphericity, enhanced in brightness and having a beautiful appearance at the time of irradiation with light and having bubbles in its center part. SOLUTION: Bubbles 3 are formed in the center part of the plastic ball, and further closed cells 2 are formed around the bubbles 3 by controlling a charging material, the mixing ratio thereof, the extrusion amount or heating and pressing degree of the material at the time of injection molding. The enhancement of brightness at the center part of the plastic ball can be achieved by the diffused reflection by the bubbles 3. COPYRIGHT: (C)2007,JPO&INPIT |
