To provide a simple method for producing nanoparticles which can be used as an additive for a polymer material to raise the refractive index of the polymer material without increasing colors and deteriorating other optical characteristics.
A metal alkoxide is hydrolyzed with an acidic alcohol solution containing an alkyl alcohol, water and an acid to form a first sol containing metal oxide nanoparticles. A second sol is formed by treating the first sol with an organosilane. A third sol is formed by treating the second sol with an organic base whose quantity is shown by the molar ratio of the organic base to the acid of a value between approximately 0.1 and approximately 0.9. The thus treated nanoparticles are a high refractive index additive to be useful for producing optical articles.
Hirokazu Ogura
Nobukazu Ito
Toshihisa Kurokawa
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