| 摘要 |
<p>PURPOSE: To obtain a transparent core material good in workability, easy in the confirmation of a bracket, and enabling an accurate correction. CONSTITUTION: This core material comprises a silicone rubber obtained by curing by an addition reaction, and has a viscosity of 300-1000Pa.s at 20 deg.C in a non-cured state, a ratio of 1.05-1.20 between viscosities measured in rotation numbers of 2min<-1> and 4min<-1> , respectively, a hardness (JISA) of 20-60 after cured, a tear strength of 5-20kgf/cm, and a 400nm wavelength light transmittance of >=70% in a thickness of 2mm.</p> |
