The present invention relates to thermoplastic compositions having; high
dimensional stability at high temperatures. In particular it is directed
to polyester compositions containing mica for use in dual-ovenable trays
and clear lids for hot food containers. According to one embodiment, the
present invention is directed to a polyester composition comprising a
polyester containing greater than about 2 to less than about 10 weight %
of a mica filler. According to another embodiment of the present
invention the mica containing polyester is prepared by the addition of
the mica during polymerization, using a buffer to minimize diethylene
glycol formation. According to another embodiment of the present
invention, the polyester composition containing greater than 2 to less
than 10 weight % mica also contains an additive package of impact
modifier, nucleating agent and pigment in a concentration from about 5
weight % to 20 weight of the total composition. According to another
embodiment of the present invention, the polyester composition containing
mica is thermoformed into a container, such as a food tray.