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Copolyimides, their preparation and the use thereof

  • US 5,145,940 A
  • Filed: 08/12/1991
  • Issued: 09/08/1992
  • Est. Priority Date: 08/17/1990
  • Status: Expired due to Fees
First Claim
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1. A copolyimide having an inherent viscosity of 0.2 to 3.0 dl/g, measured at 25°

  • C. in a solution of 0.5% by weight of said copolyimide in N-methylpyrrolidone, and comprisingA) at least one structural repeating unit of aromatic tetracarboxylic acid radicals (a) which contain 10 to 30 carbon atoms and which are unsubstituted or substituted by halogen, nitro, C1 -C4 alkyl, C1 -C4 alkoxy or phenacyl, and aromatic diamine radicals (b) which contain 6 to 30 carbon atoms and which are unsubstituted or substituted by C1 -C4 alkyl or halogen; and

    at least one additional optional structural repeating unit of aromatic tricarboxylic acid radicals (c) of 9 to 30 carbon atoms, which radicals are unsubstituted or substituted as for (a), and of identical or different diamine radicals (b), andB) at least one structural repeating unit of identical or different tetracarboxylic acid radicals (a) and aromatic diamines (d) which contain 6 to 30 carbon atoms and which are unsubstituted or substituted by C1 -C4 alkyl, and which contain at least one --SO3 M group attached to the aromatic nucleus, wherein M is H.sup.⊕

    , a mono- to trivalent metal cation, NH4.sup.⊕

    or an organic ammonium cation of 1 to 30 carbon atoms; and

    additional optional structural repeating units of identical or different aromatic tricarboxylic acid radicals (c) and identical or different diamine radicals (d), with the proviso that at least one of said diamine radicals (b) or (d) is substituted by C1 -C4 alkyl in both ortho-positions to at least one N atom.

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