| 摘要 |
PURPOSE:To form a single-layer hollow foamed body in a short period with good productivity, by adding a foaming agent and a crosslinking agent to a thermopolastic resin made up of an ethylene/vinyl acetate copolymer that has a specific vinyl acetate content or made up mainly of said ethylene/vinyl acetate copolymer to prepare a composition, and molding the composition by rotational molding. CONSTITUTION:A forming agent and a crosslinking agent are added to a thermoplastic resin made up to an ethylene/vinyl acetate copolymer that has vinyl acetate content of 5-49wt% or made up mainly of said copolymer to prepare a composition. The composition is worked by rotational molding. The amount of the foaming agent to be added will be depend on the amount of the gas that will be released from the foaming agent, the decomposition temperature thereof or the foaming ratio of the intended item, and is preferably 1-15pts.wt. to 100pts.wt. of the EVA base resin. The crosslinking agent can retain a viscosity of the EVA suitable for the foaming thereof by the crosslinking, examples, of the crosslinking agent are dicumyl peroxide, 1,3-bis-t-peroxyisopropylbenzene, etc. and the amount of the crosslinking agent used will preferably be 0.3-1.5pts.wt. to 100pts.wt. of the EVA base resin. In the rotational molding, it is required that the composition should be stuck to the inner wall of the mold uniformly, and a multiaxial rotation is preferred. The rotational frequency is generally 1-100 rotations/min that would not generate a centrifugal force. |
