| 摘要 |
A method for preparing a ball is provided to use the ball for preventing the flatness of a tire by injecting a ball having a plurality of projections on the surface of a ball into a tire. A method for preparing a ball comprises the steps of injecting 60 wt% of PET, 10 wt% of a stone powder and 30 wt% of an iron powder into an extruder containing ABS, PP or PS to extrude it, cutting the extruded one by a size of 3 mm, and drying it; injecting the obtained one to form a ball having a diameter of 40-70 mm and a thickness of 3 mm; punching a hole having a diameter of 7 mm at the upper part of the obtained ball, injecting a neodymium magnet powder into the hole, shaking it to allow the neodymium magnet powder to be stuck to the inside of the ball uniformly, injecting a foaming urethane into the hole to cure it, injecting water, and sealing the hole; and coating the surface of the ball with silicone, spraying an iron powder, and secondly coating it with silicone.
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