Hydrostability of polycarbonate polybutylene terephthalate composition
Disclosed is a process for the manufacture of a modified polyalkylene terephthalate such as modified polybutylene terephthalate. In particular, the process comprises employing a titanium-containing catalyst formed by the reaction product of tetraalkyl titanate and a complexing agent comprising a phosphorous, nitrogen or boron atom. The process is used to prepared modified polyalkylene terephthalates characterized by improved hydrostability, as well as compositions and compositions derived therefrom.
1. A compounded thermoplastic composition with improved hydrostability, comprising:
31.2 percent by weight of a modified polybutylene terephthalate, wherein the modified polybutylene terephthalate contains phosphoric acid (PA) and 115 ppm of tetraisopropyl titanate (TPT), wherein the molar ratio of TPT to PA (TPT:PA) is 1:0.8;
56.6 percent by weight of a bisphenol A polycarbonate;
2 percent by weight of linear low density polyethylene;
10 percent by weight of methylmethacrylate-butadiene styrene;
0.05 percent by weight of pentaerythritol betalaurylthiopropionate; and
0.08 percent by weight of pentaerythritol-tetrakis(3-(3,5-di-tert-butyl-4-hydroxy-phenyl-) propionate);
wherein all weight percents are based on the total weight of the compounded thermoplastic composition;
the composition is free of transesterification between the polybutylene terephthalate and bisphenol A polycarbonate;
no quencher for the catalyst complex is added to the compounded thermoplastic composition; and
the notched impact strength is maintained at 100 percent after 1000 hours of hydroaging at 80° C. and 80% relative humidity when measured according to ASTM method D256.