Abstract: An inorganic polysilazane resin of the present invention has a Si/N ratio (i.e. a ratio of contained silicon atoms to contained nitrogen atoms) of 1.30 or more. The inorganic polysilazane resin having such a high Si content can be produced by, for example, a method in which an inorganic polysilazane compound containing both Si—NH and Si—Cl is heated to react NH with Cl, a method in which a silazane oligomer (polymer) that leaves no Si—Cl bond is synthesized and a dihalosilane is added to the synthesized silazane oligomer (polymer) to perform a thermal reaction, and the like. A siliceous film can be formed by, for example, applying a coating composition containing the inorganic polysilazane resin onto a base plate and then dried and the dried product is then oxidized by bringing the dried product into contact with water vapor or hydrogen peroxide vapor and water vapor under heated conditions.
Abstract: An object of the present invention is to provide a composite of silicon oxide nanoparticles and a silsesquioxane polymer, from which a cured film having a low refractive index can be formed inexpensively. Provided are a method of producing a composite of silicon oxide nanoparticles and a silsesquioxane polymer, the method comprising reacting a silsesquioxane polymer having a silanol group at a terminal or a silane monomer with silicon oxide nanoparticles having a hydroxyl group or an alkoxy group on the surface in a mixed solvent of an aqueous solvent and an organic solvent in the presence of a phase transfer catalyst, and a composite produced by the method.