對押出結構發泡之向核心發泡程序加工之研究

Abstract

押出結構發泡產品，由於具質輕、抗彎曲剛性佳，且有絕熱隔音的特性及 良好的外觀，因此廣用於建築、廣告、傢具、電器工業、汽車、航空．． ．．等方面。文獻方面對於押出發泡產品之加工研究，大多限於不具皮層 之發泡產品，有關具有皮層的押出發泡產品，其加工之研究在文獻方面仍 然很少，尤其是向核心發泡程序，僅有少部份的專利及文獻略有介紹。本 論文擬針對向核心發泡程序進行開發研究，以期對此程序朝向最佳化提供 良好的導引。由實驗得知要維持不溢料的操作，押出機必須有穩定的輸出 ，配合適切的引取操作，真空度亦不可太高。定型模內的抽真空位置，從 離模頭一定距離後開始較為恰當,可避免因膠料由模頭押出後,即被分離而 冷卻定型,造成成品橫斷面生成空洞。定型模入口押條必須具有小的導角, 以使在開機時將膠料引取進入定型模，且避免表面產生不規則折紋。改變 定型模溫度比改變模頭溫度或發泡劑濃度對產品內部發泡形態有較顯著的 影響。 Extruded structural foam with the characteristics of lightweight, enhanced resistance to bending, good insulation to heat and sound and better surface appearance,the extruded structural foam are therefore widely used in the application of construction, adverstisement, furniture, electric housing, car industry, aerospace etc. There are several literatures available in the studies on the processing of extruded foaming. However ,most of reports are limited to the foamed parts with unskined structure.For the extruded structural foams,even few literatures are available; especially for the process of foaming toward the core, only limited patents and reports were introduced. Hence, the processing of extruded structural foams were investigated in this work to achieve a better guidence for optimizing the process. Results showed that the process must operate under the following conditions to prevent the leakage flow between the calibrator and die;(i)stable output rate must be maintained, (ii)take-off speed must be in proper range,(iii) the extent of vacuum suction cannot be keep too high. The start location of vacuum suction and solidifying in the calibrator, leading to the formation of hollow space in the interior of the part. The side wall of calibrator near the the entrance region must poss the small curvature, allowing the melt to smoothly enter the calibrator and preventing the formation of irregular wrinkles. The effect of varying the calibrator temperatures on the morphology of structural foam is more prouced than that of varing the die temperature or chemical blowing agent concentration.