Copolyimides from aliphatic and aromatic anhydrides and diamines

#The field of this invention relates to copolyimides prepared from mixtures of tetramethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride (TMCDA) and aromatic or aliphatic dianhydrides. These dianhydride mixtures are then reacted with aliphatic or aromatic diamines. These novel copolyimides are useful in the preparation of molded articles, fibers, films, laminates and coatings.

#It is known to make polyimides from pyromellitic dianhydride and diamines. (See U.S. Pat. No. 3,179,634 (1965).) British Pat. No. 570,858 discloses various processes for making fiber forming polyimides. The following Japanese patents disclose the preparation of polyimides starting with cyclobutane-1,2,3,4-tetracarboxylic dianhydride. F. Nakanishi and M. Hasegawa, Polymers, 14, 440 (1973). JA7123917-S27, JA7137733-S44, JA137734-S44, JA7219710-T23 and JA7219908-T23. In reviewing the references, it is clear the use of TMCDA and aromatic or aliphatic dianhydrides to form copolyimides useful as moldings, fibers, laminates, and coatings has not been contemplated in the prior art. The general object of this invention is to provide novel copolyimides based on mixtures of TMCDA and other dianhydride moieties that are then reacted with either aliphatic, cycloaliphatic, araliphatic or aromatic diamines. Another object is to provide a process for the manufacture of copolyimides from TMCDA-other dianhydrides and diamines.

#We have found that novel copolyimides can be prepared by reacting TMCDA and aromatic or aliphatic dianhydrides with diamines. In this process TMCDA and another dianhydride are mixed together in proportions of about 1:10 to 10:1 and these are then reacted with a diamine in a polar nitrogen containing solvent to form high molecular weight copolyimides. In this process both aliphatic, cycloaliphatic, araliphatic and aromatic diamines can be copolymerized with TMCDA and aromatic or aliphatic dianhydrides to form high molecular weight copolyimides.

#The following examples illustrate the preferred embodiment of the invention. It will be understood that the examples are for illustrative purposes only and do not purport to be wholly definitive with respect to conditions or scope of the invention. Furthermore, the structures given are not intended to convey block-type copolymers but are shown here to illustrate one possible arrangement.

#The polycondensation reaction was carried out under a nitrogen atmosphere and anhydrous conditions. 4,4'-oxydianiline (ODA) (0.0125 mole) was placed in a three-neck flask containing a teflon-coated magnetic stirrer; it was then dissolved in 30-50 ml 1-methyl-2-pyrrolidinone (NMP). The equimolar mixture (0.0125 mole) of tetramethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride (TMCDA) and pyromellitic dianhydride (PMDA) was then added to the flask through a dried powder funnel over a 10 minute period. The funnel was then washed with enough NMP to make approximately a 10% solution. The reaction vessel was heated in an oil bath to 190.degree.-200.degree. C. for 4 hours. The copolyimides were generally precipitated from solution by mixing with water in a blender, then dried in a vacuum oven at 100.degree. C. for 10 hours. The yields were in excess of 80%, usually 95%. Elemental Analysis was the following:

#______________________________________ C H N ______________________________________ Found: 68.36 4.79 7.02 Calcd: 69.17 3.76 7.02 ______________________________________