Heat resistant clear polycarbonate-polysiloxane compounds

A polycarbonate blend composition comprising:

• (a) a first polycarbonate, which is a copolycarbonate having a glass transition temperature of 170° C. or greater as measured using differential scanning calorimetry and derived from a combination of bisphenol-A and a second monomer that is free of halogens and having the structure HO-A1-Y1-A2-OH wherein each of A1 and A2 comprises a monocyclic divalent arylene group, and Y1 comprises at least one of the following:
• —O—, —S—, —S(O)—, —S(O)2—, methylene, cyclohexyl-methylene, 2-[2.2.1]-bicycloheptylidene, ethylidene, isopropylidene, neopentylidene, cyclohexylidene, cyclopentadecylidene, cyclododecylidene, and adamantylidene, wherein A1, A2 and Y1 are free of halogen atoms;
• and
• (b) a second polycarbonate, which is a polysiloxane block copolycarbonate derived from at least bisphenol-A and
• wherein the average value of E is between 30 and 50, or
• wherein the average value of E is between 30 and 50,
• wherein the siloxane content in the polysiloxane block co-polycarbonate is between 2 wt % and 10 wt % siloxane based on the total weight of the polysiloxane block co-polycarbonate
• wherein the polycarbonate blend composition comprises between 10% and 20% of the first polycarbonate and between 90 wt % and 80 wt % of the second polycarbonate based on the sum of the first and the second polycarbonate being equal to 100 wt %
• wherein the polycarbonate blend composition has a glass transition temperature (Tg) of between 148° C. and 155° C. as measured using a differential scanning calorimetry method,
• wherein the polycarbonate blend composition has a % haze of less than 3% and a % transmission of greater than 80% as measured using the method of ASTM D 1003-07;
• and,
• wherein the polycarbonate blend composition possesses at least 75% ductility in a notched izod test at −20° C. at a thickness of 0.125 inches according to ASTM D 256-10.

A polycarbonate blend composition comprising:

• (a) a first polycarbonate comprising carbonate units derived from bisphenol-A and 3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one (PPPBP), wherein the first polycarbonate has a mole % of carbonate units derived from PPPBP between 30-35 mole % and a mole % carbonate units derived from Bisphenol-A between 65 and 70 mole %, and
• (b) a second polycarbonate comprising carbonate units derived from Bisphenol-A and carbonate units derived from
• wherein, E has an average value of between 40 and 50 and wherein the wt % siloxane in the second polycarbonate is between 5 wt % and 7 wt % based on the weight of the second polycarbonate being 100%;
• wherein, the first polycarbonate comprises between 10-20 wt % and the second polycarbonate comprises between 80-90 wt % based on the wt % of the first and the second polycarbonate being 100%;
• wherein, the polycarbonate blend composition comprises between 10% and 20% of the first polycarbonate and between 80 wt % and 90 wt % of the second polycarbonate based on the sum of the first and the second polycarbonate being equal to 100 wt %;
• wherein, the polycarbonate blend composition has a glass transition temperature (Tg) of between 148° C. and 155° C. as measured using a differential scanning calorimetry method;
• wherein, a molded article of the polycarbonate blend composition has a % haze of less than 3% and a % transmission of greater than 80% as measured using the method of ASTM D 1003-07 at 0.125 inches in part thickness;
• wherein the polycarbonate blend composition possesses at least 75% ductility in a notched izod test at −20° C. at a thickness of 0.125 inches according to ASTM D 256-10.