Preparation of Silica Hollow Spheres Used as Filler for Paper

Silica of hollow structure exhibits a number of special characteristics. In this paper, a new method for preparing hollow silica spheres, which can be used as filler for paper, was reported. In this approach, when silica shells were coated on polyvinylacetate (PVAc) template particles by the sol-gel method, the PVAc cores could be dissolved synchronously, forming hollow spheres. Neither additional dissolution nor a calcination process was needed to remove the PVAc cores. The morphology of the hollow silica spheres was characterized by TEM. It was shown that the hollow silica spheres with 130-400nm in diameter and 15-35nm in the shell thickness could be synthesized. The possible formation mechanism was also proposed. The possibility and potential advantages in usage as filler for paper were analyzed theoretically. It was believed that this filler can improve the printability of the paper, and reduce its density compared with traditional fillers.