Addition curable type silicone resin composition, process for producing composition, and optical semiconductor apparatus

An addition curable type silicone resin composition which comprises:

• (a) an organopolysiloxane having two or more alkenyl groups bonded to a silicon atom(s) in one molecule, and having a viscosity at 25° C. of 50 to 100,000 mPa·s,
• (b) an organopolysiloxane represented by the following average composition formula (1), and is a liquid having a viscosity at 25° C. of 1,000 mPa·s or more or a solid:
• an amount of the component (b) being more than 0 part by mass and less than 80 parts by mass based on 100 parts by mass of a total of the component (a) and the component (b),
• (R1R22SiO1/2)m(R1R2SiO2/2)n(R22SiO2/2)p(R1SiO3/2)q(R2(OR3)SiO2/2)r(SiO4/2)s (1)
• wherein, R1 represents a monovalent hydrocarbon group which may contain an alkenyl group;
• R2 represents a monovalent hydrocarbon group which does not contain an alkenyl group, and 80% or more of the whole R2 is a methyl group;
• R1 represents a hydrogen atom or an alkyl group;
• “m”, “n”, “p”, “q”, “r”, and “s” are numbers satisfying m≥0, n≥0, p≥0, q≥0, r≥0, s≥0, and are numbers satisfying m+n>0, q+r+s>0, m+n+p+q+r+s=1,
• (c) an organohydrogen polysiloxane represented by the following average composition formula (2), having two or more SiH bonds in one molecule, and having a viscosity at 25° C. of 1,000 mPa·s or less:
• in an amount that a number of the SiH bonds of the component (c) being 0.5 to 5.0-fold based on a total of a number of the alkenyl groups of the component (a) and the component (b),
• R4aHbSiO(4-a-b)/2 (2)
• wherein, R4 represents a monovalent hydrocarbon group which does not contain an alkenyl group, and 50% or more of the whole R4 is a methyl group;
• and “a” and “b” are numbers satisfying 0.7≤a≤2.1, 0.001≤b≤1.0, and 0.8≤a+b≤3.0,
• (d) a platinum group metal catalyst:
• in an amount of 1 to 500 ppm in terms of a mass of metal atoms based on a total of the components (a) to (c), and
• (e) a polyorganometallosiloxane containing an Si—O—Ce bond, and an Si—O—Ti bond, a Ce content of which is 50 to 5,000 ppm, a Ti content of which is 50 to 5,000 ppm, and having a viscosity at 25° C. of 10 to 10,000 mPa·s:
• in an amount of 0.01 to 5 parts by mass based on 100 parts by mass of a total of the components (a) to (d),
• which cures by heating,
• wherein a total light transmittance of a sheet having a thickness of 2 mm of a cured product of the composition at a wavelength of 400 nm of 80% or more, and a weight reduction ratio of the cured product after storage at 250° C. for 500 hours of within 10%.