In many optical items (computer displays, transparent plastic lenses etc), there is a need for the outer layer to provide an anti-reflective quality to improve visibility. This requires the layer to have a low refractive index. Although fiuoro-plastics can be used, because of their low refractive index and alkali resistance, they do not provide sufficient mar resistance. Mixtures do exist that require curing above 100°C, which is seen as a disadvantage due to deformation of the substrate. Mixtures of porous and/or hollow inorganic oxide fine particles, hydrolytic condensates of organosilicon compounds comprising a bis-silane compound of a specific structure, and compounds capable of generating acid upon light exposure can be used to overcome the described limitations. As silanol can be cured under the action of the generated acid, the system does not require functional groups which may cause an increase in the refractive index.
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