Patent ID: 7820253

Claim:
A negative birefringence film prepared from a poly(aryletherimide) which is the reaction product of a dianhydride and a diamine; where the dianhydride is 4,4′-[4,4′-(p-phenyleneoxy)isopropylidene]bis(phthalic anhydride) (BisADA),bis(3,4-dicarboxyphenyl)ether dianhydride (ODPA), 4,4′-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride (BPEDA), or 1,4-bis(3,4-dicarboxyphenyloxy)phenyl dianhydride (BPQDA), or a mixture of BisADA, ODPA, BPEDA, or BPQDA and one or more dianhydride(s) chosen from the group consisting of: 3,3′,4,4′-tetracarboxylicbiphenyl dianhydride (BPDA) and 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride (6FDA), and where the diamine is 1,4-bis(2-trifluoromethyl-4-aminophenoxy)-2,5-di(t-butyl)benzene (BTBDA), or mixtures thereof with one or more diamine(s) chosen from the group consisting of 4,4′-diaminophenyl ether, 2-trifluoromethyl-4,4′-diaminophenyl ether, 2-trifluoromethyl-2′-methyl-4,4′-diaminophenyl ether, 1,4-bis(4-aminophenoxy)benzene, 4,4′-bis(4-aminophenoxy)biphenyl, 4,4′-bis(3-aminophenoxy)biphenyl, 4,4″-bis(4- aminophenoxy)terphenyl, 4,4′-bis(3-aminophenoxy)terphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl] 1,1,1,3,3,3-hexafluoropropane, 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, 2,2′-bis(trifluoromethyl)-4,4′-diaminophenyl ether (6FODA), 4,4′-bis(4-amino-2-trifluoromethylphenoxy)biphenyl (6FOBDA), 4,4′-bis(4-amino-2-trifluoromethylphenoxy)-3,3′,5,5′-tetramethylbiphenyl, 4,4′-bis(4-amino-2-trifluoromethylphenoxy)-3,3′,5,5′-tetra(tert-butyl)biphenyl, 4,4′-bis(3-amino-trifluoromethylphenoxy)biphenyl, 4,4″-bis(4-amino-2-trifluoromethylphenoxy)terphenyl, 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)-phenyl]propane, 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl] 1,1,1,3,3,3-hexafluoropropane, 3,3′-dimethyl-4,4′-diamino biphenyl (OTOL), and 1,4-bis(2-trifluoromethyl-4-aminophenoxy)-2-t-butylbenzene, wherein when a mixture of dianhydrides is present, they are present in a molar amount of between 99 to 1 (99:1) and 1 to 99 (1:99); and the film has a negative birefringence greater than 0.01, at a thickness of less than 15 μm, when the poly(aryletherimide) is solution cast or coated onto a substrate.