US 12,291,640 B2
Flame-retardant polyorganosiloxane composition, flame-retardant cured product, and optical member
Kikuo Mochizuki, Tokyo (JP); and Hidefumi Tagai, Tokyo (JP)
Assigned to MOMENTIVE PERFORMANCE MATERIALS JAPAN LLC, Tokyo (JP)
Filed by MOMENTIVE PERFORMANCE MATERIALS JAPAN LLC, Tokyo (JP)
Filed on Dec. 11, 2020, as Appl. No. 17/118,940.
Application 17/118,940 is a continuation of application No. PCT/JP2019/023070, filed on Jun. 11, 2019.
Claims priority of application No. 2018-111812 (JP), filed on Jun. 12, 2018.
Prior Publication US 2021/0102070 A1, Apr. 8, 2021
Int. Cl. C08L 83/04 (2006.01); C08L 83/06 (2006.01); G02B 1/04 (2006.01); H10H 20/854 (2025.01)
CPC C08L 83/06 (2013.01) [C08L 83/04 (2013.01); G02B 1/041 (2013.01); C08L 2201/02 (2013.01); C08L 2205/025 (2013.01); C08L 2205/03 (2013.01); H10H 20/854 (2025.01)] 13 Claims
 
1. A flame-retardant polyorganosiloxane composition comprising:
(A) a straight-chain polyorganosiloxane represented by general formula:

OG Complex Work Unit Chemistry
wherein R1s represent an alkenyl group or a substituted or unsubstituted alkyl group, n represents the number of repeating units, and a sum of n and the number of end groups (n+2) defines an average polymerization degree, the straight-chain polyorganosiloxane having two or more alkenyl groups bonded to silicon atoms on average in one molecule and having a viscosity at 25° C. of 80,000 to 1,000,000 mPa s;
(B) 30 to 80 mass % of a polyorganosiloxane having a resin structure to a total of the component (A) and the component (B), the polyorganosiloxane having 1.5 or more alkenyl groups bonded to silicon atoms on average in one molecule, wherein the component (B) comprises at least one selected from the group consisting of phosphorus and an alkali metal, wherein the component (B) comprises potassium as the alkali metal, a content ratio of all alkali metals in the component (B) is 0.6 ppm by mass or more, and the polyorganosiloxane comprises:
a monofunctional siloxane unit represented by a formula: (CH3)2(CH2═CH) SiO1/2;
a monofunctional siloxane unit represented by a formula: (CH3)3SiO1/2; and
a tetrafunctional siloxane unit represented by a formula: SiO4/2;
(C) a polyorganohydrogensiloxane having three or more hydrogen atoms bonded to silicon atoms on average in one molecule, wherein an amount of the hydrogen atoms bonded to the silicon atoms in the component (C) becomes 1.0 to 3.0 mol to a total 1 mol of the alkenyl groups in the component (A) and the alkenyl groups in the component (B); and
(D) a catalytic amount of a hydrosilylation reaction catalyst,
wherein a total content of phosphorus and an alkali metal is 10 mass ppm or less, and
a total content of all alkali metals in the flame-retardant polyorganosiloxane composition is less than 0.4 mass ppm.