DESIGN OF CLARIFIED POLYPROPYLENE UTILIZING A NOVEL CLARIFIER

摘要

NA-71, a newly developed "Advanced clarifier" ADV-1 exhibited a higher crystallization temperature, shorter crystallization half time resulting in providing the a-form PP crystal, a higher crystallization rate and degree of crystallinity. A lower molding temperature was preferred to maximize the clarifying ability of ADV-1. The clarifier improved haze effectively and provided excellent transparency even at lower loading levels of around 0.1 wt%, and exhibited the superior clarity in thin molded articles. Higher stiffness of 25% increase in flexural modulus can be achieved by using the clarifier. Thus, ADV-1 gave an excellent balance between clarity and stiffness. A similar tendency was confirmed in PP film application. On the other hand, the haze of molded articles with the clarifier varied with a comonomer randomness referred as comonomer sequence distribution or run numbers. Polydispersity also affected the haze values. ADV-1 provided superior transparency when used with polypropylenes of higher randomness and a broader molecular weight distribution. This suggests that appropriate design of base resin in combination with the clarifier is essential for the design of superior clarified polypropylene grades. In summary, ADV-1 is expected to diversify the design of clarified polypropylene and to expand the application range for these grades.