表面エネルギー成分に基づく硬質コーティングの離型性評価に関する研究

抄録

Most of plastic products are made by injection moldings, in wich there often is a problem of demoulding charactetristics, i.e. adhesion or too large/small friction between moulded parts and mould cavitiy or core surfaces. Hard coatings such as chromium nitride (CrN), titanium nitride (TiN) etc. are often applied to the surfaces to improve demoulding characteristics as well as abrasive resistance against hard fillers in plastic pellets. However, there is little systematic study showing advantages and disadvantages of such coatings in terms of demoulding characteristics and selection of coatings often depends on experience of engineers. In this study, we aim to establish a method to predict demoulding characteristics on the basis of interfacial tension estimated by contact angle measurement. The surface tension and dispersive and polar components of some hard coatings (TiN, CrN, DLC) deposited by PVD and polycarbonate (PC) were determined by a sessile drop method using some probe liquids. A largest interfacial tension against PC was obtained for the TiN, which may indicate smaller demoulding forces.