Flame retardant resin compositions

A flame retardant resin composition comprising

• (A) 100 parts by weight of a synthetic resin containing an aromatic ring in a molecule, and
• (B) 0.1 to 10 parts by weight of an organosiloxane containing phenyl and alkoxy radicals, represented by the following average compositional formula (1):
• R1mR2nSi(OR3)p(OH)qO(4−m−n−p−q)/2 (1)
• wherein R1 is phenyl, R2 is a monovalent hydrocarbon radical of 1 to 6 carbon atoms excluding phenyl, R3 is a monovalent hydrocarbon radical of 1 to 4 carbon atoms, and letters m, n, p and q are numbers satisfying 0.5≦m≦2.0, 0≦n≦0.9, 0.42≦p≦2.5, 0≦q≦0.35, and 0.92≦m+n+p+q≦2.8, said organosiloxane (B) containing at least 50 mol % of units of formula (2):
• R4—SiX3 (2)
• wherein R4 is as defined for R1 or R2, X is —OH, —OR3 or siloxane residue, at least one of the three X radicals attached to one silicon atom is a siloxane residue, said siloxane residue is represented by O1/2, O2/2, and O3/2 when one, two and three of the X radicals are siloxane residues, respectively and these oxygen atoms bond with other silicon atoms to form siloxane bonds.