Poly amic acid system for polyimides

Abstract

A poly amic acid precursor containing a combination of tetrahydrofuran and N-methylpyrrolidinone as cosolvents is described. Utilizing the combination of tetrahydrofuran and N-methylpyrrolidinone allows for the removal of significant portions of the solvent during the formation of the polyimide. The removal of tetrahydrofuran and N-methylpyrrolidinone can be done without the use of preheating zones so as to allow for the large scale production of polyimide articles.

1 - 13 . (canceled)  
     
     
         14 . A polyimide laminate comprising: 
 a polyimide layer; and    a metal foil, wherein said polyimide laminate is produced by casting a polyamic acid precursor comprising at least one diamine and at least one anhydride in a cosolvent of tetrahydrofuran and N-methylpyrrolidinone onto a surface of the metal foil, followed by heating the polyamic acid solution to form the polyimide layer.    
     
     
         15 . The polyimide laminate of  claim 14  wherein said polyamic acid precursor contains an amount of tetrahydrofuran ranging from about 1% to about 90% by volume of solvent of tetrahydrofuran and N-methylpyrrolidinone.  
     
     
         16 . The polyimide laminate of  claim 14  wherein said polyamic acid precursor further contains at least 1% weight of an inorganic filler selected from the group consisting of mica, silica, calcium carbonate, calcium phosphate, calcium silicate, talc, and a combination thereof.  
     
     
         17 . The polyimide laminate of  claim 14  wherein the at least one anhydride comprises 4,4′-oxydiphthalic anhydride and 3,3′-biphenyltetracarboxylic dianhydride.  
     
     
         18 . The polyimide laminate of  claim 17  wherein the mole ratio of 3,3′,4,4′-biphenyltetracarboxylic dianhydride to 4,4′-oxydiphthalic anhydride ranges from about 25% to about 75% 3,3′,4,4′-biphenyltetracarboxylic dianhydride.  
     
     
         19 . The polyimide laminate of  claim 17  wherein the mole ratio of 3,3′,4,4′-biphenyltetracarboxylic dianhydride to 4,4′-oxydiphthalic anhydride is about 50% 3,3′,4,4′-biphenyltetracarboxylic dianhydride.  
     
     
         20 . The polyimide laminate of  claim 14  wherein the diamine is 3,4′-oxydianiline.  
     
     
         21 . The polyimide laminate of  claim 14  wherein the polyamic acid precursor is quantitatively pumped and fed through a slit die and cast onto a surface of a metal foil.  
     
     
         22 . The polyimide laminate of  claim 14  wherein the metal foil is copper.  
     
     
         23 - 26 . (canceled)