| 摘要 |
An addition curable silicone resin composition is provided to obtain a cured product of a hard resin having excellent flexibility and impact resistance and low surface tackiness, and to obtain a lens having excellent impact resistance, flexibility and transparency. An addition curable silicone resin composition comprises: (A) a resin-structured organopolysiloxane comprising R1SiO1.5 units, R22SiO units and R3aR4bSiO(4-a-b)/2 units (wherein each of R1, R2 and R3 is OH, methyl, ethyl, propyl, cyclohexyl or phenyl, R4 is vinyl or allyl, a is 0, 1 or 2, b is 1 or 2 and z+b is 2 or 3), wherein at least a part of the R22SiO units are repeated continuously and the number of repeated units is 5-50; (B) a resin-structured organohydrogenpolysiloxane comprising R1SiO1.5 units, R22SiO units and R3cHdSiO(4-c-d)/2 units (wherein each of R1, R2 and R3 is as defined above, c is 0, 1 or 2, d is 1 or 2, and c+d is 2 or 3), wherein at least a part of the R22SiO units are repeated continuously and the number of repeated units is 5-50, and component (B) is used in such an amount that the molar ratio of the hydrogen atoms bonded to Si in (B) to the combined moles of the vinyl and allyl groups in (A) is 0.1-4.0; (C) an organopolysiloxane other than (A), which has at least two alkenyl groups per molecule, and is present as a liquid or solid at 25 deg.C; (D) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to Si per molecule, and showing a viscosity of 0.5-50,000 mPa.s at 25 deg.C but a viscosity of 10-100,000 mPa.s at 25 deg.C in the state of a mixture with the organopolysiloxane(C), wherein components (C) and (D) are used in such an amount that the molar ratio of the hydrogen atoms bonded to Si in (B) and (D) to the combined moles of the alkenyl groups in (A) and (C) is 0.1-4.0; and (E) a curing effective amount of a Pt-based metal catalyst. |
