Hollow microspheres

摘要

A process of forming hollow microspheres containing carbon or a polymer which is a carbon precursor. The process comprises forming a solution in a liquid solvent of a polymer having the following properties (a) a molecular weight of at least 10,000 and a long chain structure; (b) an ability to be coagulated by or precipitated from the solution by a non-solvent for the polymer; (c) an ability to form a continuous stretchable film when coagulated or precipitated from solution; (d) a chemical structure which is infusible or capable of being rendered infusible, and (e) a high carbon yield of at least 30% by weight upon being carbonized in a non-reactive atmosphere. An insoluble particulate blowing agent is incorporated into the solution and the solution is then divided into droplets and the droplets are introduced into a liquid bath containing a suitable non-solvent for the polymer. The non-solvent causes the polymer to precipitate or coagulate rapidly and simultaneously the blowing agent is decomposed to generate a gas within the droplets so that hollow microspheres are formed. The microspheres are then optionally subjected to carbonization in a non-reactive atmosphere at high temperature to convert the polymer to carbon. Uniformly-sized relatively large hollow microspheres can be produced by this process.