Extrusion & Post
11 조회수
Delamination of PP products overmolded with TPE/TPU
문제 현상
After two-shot molding (overmolding) of PP substrate with TPE/TPU soft rubber, the soft-hard rubber joint delaminates and peels.
원인 분석
PP and TPE/TPU have different shrinkage rates, and the mold is not designed for differential shrinkage, causing interfacial stress; during two-shot molding, the substrate temperature is low and the interface is not fully fused, or the soft rubber grade does not match PP—all cause insufficient bonding force and delamination.
해결 방법
①Select a special TPE/TPU grade that can chemically bond with PP; ②design the mold with differential shrinkage compensation for the two materials; ③preheat the PP substrate before two-shot molding to increase the interface temperature; ④optimize the soft rubber injection temperature and speed to ensure interfacial fusion; ⑤perform peel strength verification.
핵심 요약
For PP overmolding delamination, grasp the three points of 'grade matching + interface temperature + differential shrinkage': the soft and hard rubbers must be bondable, the substrate must be preheated, and the mold must be designed for differential shrinkage—all three are indispensable.
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