Flame and hot wire resistant polycarbonate compsn. useful in electrical industry - using an aromatic polycarbonate contg. 1,1-bis(4-hydroxyphenyl)-3,3,5-tri:methyl-cyclohexane units and an aromatic bromine cpd. as flame retardant

摘要

Thermoplastic, hot-wire resistant, polycarbonate composition contains an aromatic polycarbonate with MW of at least 10,000 and contg. units of formula (1); an aromatic bromine cpd. making up 0.5-6 wt.% of the mixture; and opt. 0.05-5 wt.% of other customary flame retardants. In formula (I), R1, R2 = H halogen, esp. Cl, Br, 1-8C alkyl, 5-6C cycloalkyl, 6-10C aryl esp. phenyl and 7-12C aralkyl pref phenyl- 1-4C alkyl and esp. benzyl; m = 4-7, pref. 4-5; R3, R4 = H, or 1-6C alkyl; and X = carbon; with the proviso that on at least one X atom R3 and R4 are both alkyl. Also claimed in the use of the composition to form hot-wire resistant injection mouldings. The polycarbonate pref. contains at least 10% of the structure (1) and pref. more than 30 mol.%. The pref. Br-contg. cpd. is a bromine-substd. divalent phenol, a brominate phthalimide or phthalimide sulphate or a brominated polymer. USE/ADVANTAGE - In the electrical and electronics industries. The composition fulfils both the flame-proof requirements of UL 94 and the hot-wire resistant properties of French standard C20-455. In an example, 98.53 pts.wt. of polycarbonate from 35 mol.% of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane and 65 mol.% of bisphenol A, 1 pt.wt. of an oligocarbonate from tetrabromobisphenol A, 0.15 pts.wt. of N,N-hexamethylene-bis-tetrabromobisphenol A, 0.15 pts.wt. of N,N-hexamethylene-bis-tetrachlorophthalimide and 0.5 pts.wt. of PTFE were mixed in an extruder and injection moulded. The composition showed a UL 94 figure of V-2 and a C20-455 result of tm = 14 and S5 = 18, with an oxygen index of 36.