Stabilizer mixtures and their use in polycarbonates

Mixtures comprising

• A) phosphines of formula (I) ##STR10## in which R is an unsubstituted or substituted C.sub.6 -C.sub.14 -aryl group and
• in which R.sup.1 is one of the following groups (Ia) to (Ih) ##STR11## in which R has the meaning quoted for formula (I), "n" and "m" are a whole number from 1 to 7, independently of each other in each case,
• and wherein the H-atoms of the groups (Ia) to (Ic) can also be replaced by ##STR12## and wherein R.sup.1 can also be 4-phenyl-phenyl or .alpha.-naphthyl when both R's in formula (I) are also 4-phenyl-phenyl or .alpha.-naphthyl in each case,
• wherein the 4-phenyl-phenyl and the .alpha.-naphthyl groups can also be substituted, and
• B) silicon compounds of formula (II)
• R.sup.2.sub.a --Si(OR.sup.3).sub.b (II)
• in which a+b=4, b is at least 1, R.sup.2 is H or C.sub.1 -C.sub.18 -alkyl, C.sub.2 -C.sub.18 -alkenyl, C.sub.6 -C.sub.24 -aryl, C.sub.7 -C.sub.24 -alkylaryl or C.sub.7 -C.sub.24 -aralkyl and R.sup.3 is C.sub.1 -C.sub.18 -alkyl, C.sub.2 -C.sub.18 -alkenyl, C.sub.5 -C.sub.10 -cycloalkyl or C.sub.7 -C.sub.24 -aralkyl,
• wherein the molar ratio of (A) to (B) is between 0.01 and 3.5.