Hoechst Celanese Corporation

Paul J Harget

Paul N Chen, Sr

Tai-Shung Chung

Thomas J Dolce

A composite comprising a polyarylate or an aromatic polybenzimidazole article and a coating on at least one surface of the article comprised of a blend of from about 5 to about 95 weight percent of a polyarylate and from about 95 to about 5 weight percent of an aromatic polybenzimidazole. A process for preparing the composites comprises dissolving in a mutual solvent from about 5 to about 95 weight percent of the aromatic polybenzimidazole to about 95 to about 5 weight percent of the polyarylate, based on the total weight of those polymers, heating a polyarylate or aromatic polybenzimidazole article to a surface temperature over 100.degree. C., e.g., from about 120.degree. C., to about 180.degree. C., and then coating the polyarylate or aromatic polybenzimidazole article with the solution and subsequently evaporating the solvent, thereby producing a dried coating of a blend of a polyarylate and an aromatic polybenzimidazole on at least one surface of the article. The composites, particularly in the form of films, fibers or fibrets, may be post-treated with heat or sulfuric acid in order to minimize their shrinkage when subsequently subjected to heat and in order to increase their resistance to solvents and acid.

Composites of aromatic polybenzimidazoles and polyarylates

A novel miscible composition comprising from about 5 parts by weight to about 95 parts by weight of a polyarylate and from about 95 parts by weight to about 5 parts by weight of an aromatic polybenzimidazole. In a composition mostly comprised of an aromatic polybenzimidazole, it is preferred that the polyarylate be present in the composition in an amount sufficient to make the aromatic polybenzimidazole more thermally processable and also less susceptible to moisture. More preferably, such compositions are comprised of from about 60 parts by weight to about 95 parts by weight of an aromatic poloybenzimidazole and from about 40 parts by weight to about 5 parts by weight of a polyarylate. Most preferably, such compositions are comprised of at least about 10 parts by weight of a polyacrylate. In a composition mostly comprised of a polyarylate, it is preferred that the aromatic polybenzimidazole be present in an amount sufficient to render the polyarylate less sensitive to solvents, and to increase the thermal stability of the polyarylate. Preferably, the aromatic polybenzimidazole is present in such compositions in an amount sufficient to result in a composition with greatly enhanced solvent resistance. More preferably, such compositions are comprised of from about 60 parts by weight to about 95 parts by weight of a polyarylate and from about 40 parts by weight to about 5 parts by weight of an aromatic polybenzimidazole. Most preferably, such compositions should contain at least about 25 to about 30 parts by weight of a polybenzimidazole in order to render the polyarylate component much more resistant to solvents at room temperature. In addition to improving solvent resistance, greater amounts of aromatic polybenzimidazole in the composition substantially increase the thermal and physical properties of the composition, giving excellent price-performance characteristics. The compositions, particularly in the form of films or fibers, may be post-treated with heat or sulfuric acid in order to minimize their shrinkage when subsequently subjected to heat and in order to increase their resistance to solvents and acid.

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West Milford, NJ, United States of America

Paul J Harget