Polyesters are well-known commercially available resinous materials which are high temperature, high performance thermoplastic engineering polymers with a combination of good thermal and good mechanical properties. These resins which are typically prepared by the condensation reaction of dihydroxy compounds and aromatic dicarboxylic acids are suitable in a variety of applications.
The art has long recognized the advantages of modifying the properties of resinous polymers by copolymerization techniques. In this regard, the preparation of block copolymers based on polyether/polyester carbonate has been disclosed in U.S. Pat. No. 5,169,907. In the process thus disclosed a polyether ketone (or other polyaryl ether)/polycarbonate block copolymer is prepared by transesterification of an ester containing polyaryl ether and a polycarbonate. Also relevant is U.S. Pat. No. 4,517,354 which disclosed certain polysulfone which may upon reacting with polyols or with polyamines yield the corresponding polyesters or polyamides. Blends of a poly(aryl ether), a polyalkylene terephthalate and a nucleating agent have been disclosed in U.S. Pat. No. 4,906,500. Blends of polyether sulfone with polyalkylene terephthalate have been disclosed in U.S. Pat. No. 5,151,462. Also relevant is European Patent Application 133,907, which disclosed a blend of polyarylether sulfone with a thermoplastic polyester. Polyarylates having improved hydrolytic stability were disclosed in U.S. Pat. No. 5,036,150. The arylates have repeating units derived from bis-(3,5-dimethyl-4-hydroxyphenyl)-sulfone optionally a dihydric phenol and a mixture of isophthalic acid and terephthalic acid or their derivatives.
It is an object of the present invention to provide block copolymers of polyethersulfone/polyester which have a predictable block length.
It is another object of the present invention to provide polyethersulfone sulfone/polyester block copolymers which may be formed in an extruder.
It is also an object of the present invention to provide a process for producing polyethersulfone sulfone/polyester block copolymer via reactive melt blending.
Another object of the present invention to provide a process for producing polyethersulfone sulfone/polyester block copolymers which may be carried out in a relatively short period of time.
These and other objects which will be apparent to those skilled in the art are accomplished by copolymerizing an ester group containing polyethersulfone (herein ePSU) with a thermoplastic polyester. This copolymerization is carried out, with or without a catalyst, by reactive melt blending of the components.