Patent ID: 8647679
Filing Date: 2014-02-11
Classification: A61K,A61Q,B82Y,C01G,C01P,C09C

Abstract:
1. Core-shell type zinc oxide microparticles, wherein the 1) a core portion thereof is a secondary particle formed by a spherical aggregation of primary particles of zinc oxide, 2) the secondary particle is of spherical shape and is not of a non-spherical shape, 3) a polymer layer that forms a shell portion exists on a surface of the secondary particle, wherein the polymer layer is composed of polymer crosslinked between polyvinylpyrrolidone (PVP) and PVP, or polymer crosslinked between hydroxypropyl cellulose (HPC) and HPC, or polymer crosslinked between PVP and HPC, or polymer of PVP or HPC crosslinked between PVP or HPC and polyethylene glycol (PEG), or polymer of PEG crosslinked between PEG and PEG, and 4) the microparticles have an average particle diameter of from 50 nm to 1,000 nm, wherein the microparticles are made by heating and refluxing a mixture comprising a zinc salt hydrate and one or more polymers selected from the group consisting of PVP, HPC, and PEG, in a polyol as a high-boiling-point organic solvent, in the absence of water.