| 摘要 |
PURPOSE:To obtain a foamable synthetic resin molding unit of high dimensional accuracy by heating foamable preliminary synthetic resin particles under pressure to thermally deforming temperature of higher of resin to reduce the volume of the particles by thermal shrinkage, simultaneously generating internal pressure in the air bubbles in the particles, then cooling it to the temperature lower than the thermally deforming temperature of the resin to obtain high internal pressure foamable particles having internal pressure higher than the atmospheric pressure, heating to expand in the mold, and fusion-bonding it. CONSTITUTION:Preliminary foamable particles already foamed are heated to the thermally deforming temperature or higher of the resin of the particles under pressure, the expansion of gas in the particles by heating is suppressed by pressure to cause thermal shrinkage of air bubble film for forming the foamable particles without leaking the gas in the particles out of the particles to reduce the substantial volume of the particles, the foaming magnification of the particles is decreased, and cooled to the temperature lower than the thermally deforming temperature of the resin. As a result, the particles become high internal pressure foamable particles having particle internal pressure higher than the atmospheric pressure. The particles are filled in an injection mold, heated to the thermally deforming temperature or higher of the resin, expanded, fusion-bonded, thereby obtaining a foamable molding unit. |
