Thermoplastic copolyimides and composites therefrom

A process for improving the melt processibility of a thermoplastic copolyimide comprising the steps of:

• (a) reacting one or more of dianhydrides of formula (I) ##STR10## where Z is a tetravalent organic radical selected from the group consisting of a carbocyclic aromatic containing radical and a heterocyclic aromatic containing radical where each anhydride group is located on an aromatic ring with the carbonyl units in an ortho orientation relative to one another with an alcohol to form a dialkyl diester;
• (b) dissolving the dialkyl diester in a solvent containing at least one first diamine of formula (II) wherein the first diamine has a basicity constant of less than 10.sup.-10,
• H.sub.2 N--Q--NH.sub.2 (II)
• and at least one second diamine of formula (III) wherein the second diamine has a basicity constant of at least 10.sup.-10,
• H.sub.2 N--Q'--NH.sub.2 (III)
• where Q is divalent organic radical selected independently from the group consisting of a carbocyclic aliphatic radical, a carbocyclic aromatic containing radical, and a heterocyclic containing radical, the term carbocyclic aromatic containing radical and heterocyclic aromatic containing radical used to define Q includes any radical which has the anhydride groups attached to one or more aromatic ring(s) and has the amine groups attached to one or more aromatic ring(s), and where Q' is an electron-deficient divalent heterocyclic group having a 5- or a 6-membered ring containing from 1-3 heteroatoms, at least one of the heteroatoms being nitrogen and further wherein a first diamine is capable of a transimidization reaction upon incorporation into the polyimide backbone, and wherein a second diamine is not capable of undergoing a transimidization reaction upon incorporation into the polyimide backbone, the first diamine being added in an amount of about 1-50 mole percent in relation to the second diamine;
• and
• (c) heating until the dialkyl diester and the first and second diamines react thereby forming from about 1-50 mole percent of a thermoplastic polyimide of repeating unit formula (IV), ##STR11## a balance of the thermoplastic polyimide of repeating unit formula (V), ##STR12## the thermoplastic polyimide being melt processible at a pressure less than or equal to 250 psi, and capable of undergoing transimidization in the melt allowing for enhanced melt flow and the rearrangement of repeat unit sequences along the polymer backbone.

A process for improving the melt processibility of a thermoplastic copolyimide having comprising the steps of:

• (a) reacting one or more of dianhydrides of formula (I) ##STR13## where Z is a tetravalent organic radical selected from the group consisting of a carbocyclic-aromatic containing radical and a hetero-cyclic aromatic containing radical where each anhydride group is located on an aromatic ring with the carbonyl units in an ortho orientation relative to one another with an alcohol to form a dialkyl diester;
• (b) reacting the dialkyl diester with at least one first diamine of formula (II) wherein the first diamine has a basicity constant of less than 10.sup.-10,
• H.sub.2 N--Q--NH.sub.2 (II)
• in a solvent to form a precursor oligomer solution;
• (c) reacting at least one second diamine of formula (III) wherein the second diamine has a basicity constant of at least 10.sup.-10,
• H.sub.2 N--Q'--NH.sub.2 (III)
• with the oligomer solution, where Q is divalent organic radical selected independently from the group consisting of a carbocyclic aliphatic radical, a carbocyclic aromatic containing radical, and a heterocyclic containing radical, the term carbocyclic aromatic containing radical and heterocyclic aromatic containing radical used to define Q includes any radical which has the anhydride groups attached to one or more aromatic ring(s), and has the amine groups attached to one or more aromatic ring(s), and where Q'is a highly electron-deficient divalent heterocyclic group having a 5- or a 6-membered ring containing from 1-3 heteroatoms, at least one of the heteroatoms being nitrogen and further wherein a first diamine is capable of a transimidization reaction upon incorporation into the polyimide backbone, and wherein a second diamine is not capable of undergoing a transimidization reaction upon incorporation into the polyimide backbone, the first diamine being added in an amount of about 1-50 mole percent in relation to the second diamine to form a viscous oligomer solution;
• (d) coating the viscous solution on a substrate;
• (e) drying the coated substrate to remove the solvent thereby forming from about 1-50 mole percent of a thermoplastic polyimide of repeating unit formula (IV), ##STR14## a balance of the thermoplastic polyimide of repeating unit formula (V);
• and ##STR15## (f) consolidating the coated substrate in an autoclave by subjecting the substrate to a heating and pressure cycle wherein the pressure is less than or equal to 250 psi.

A thermoplastic copolyimide melt-processible at a pressure less than or equal to 250 psi, comprising:

• (a) from 1-50 mole percent of a thermoplastic polyimide of repeating unit formula (IV);
• and ##STR16## (b) a balance of the thermoplastic polyimide of repeating unit formula (V) ##STR17## wherein the thermoplastic copolyimide is the product of a reaction of one or more dianhydrides of formula (I) ##STR18## where Z is a tetravalent organic radical selected from the group consisting of a carbocyclic-aromatic containing radical and a hetero-cyclic aromatic containing radical where each anhydride group is located on an aromatic ring with the carbonyl units in an ortho orientation relative to one another, with at least one first diamine of formula (II) wherein the first diamine has a basicity constant of less than 10.sup.-10,
• H.sub.2 N--Q--NH.sub.2 (II)
• and at least one second diamine of formula (III) wherein the second diamine has a basicity constant of at least 10.sup.-10,
• H.sub.2 N--Q'--NH.sub.2 (III)
• where Q is divalent organic radical selected independently from the group consisting of a carbocyclic aliphatic radical, a carbocyclic aromatic containing radical, and a heterocyclic containing radical, the term carbocyclic aromatic containing radical and heterocyclic aromatic containing radical used to define Q includes any radical which has the anhydride groups attached to one or more aromatic ring(s) and has the amine groups attached to one or more aromatic ring(s), and where Q' is an electron-deficient divalent heterocyclic group having a 5- or a 6-membered ring containing from 1-3 heteroatoms, at least one of the heteroatoms being nitrogen and further wherein a first diamine is capable of a transimidization reaction upon incorporation into the polyimide backbone, and wherein a second diamine is not capable of undergoing a transimidization reaction upon incorporation into the polyimide backbone, the first diamine being added in an amount of about 1-50 mole percent in relation to the second diamine, and capable of undergoing transimidization in the melt allowing for enhanced melt flow and the rearrangement of repeat unit sequences along the polymer backbone.