Method for the manufacture of a poly(imide) prepolymer powder and varnish, poly(imide) prepolymer powder and varnish prepared thereby, and poly(imide) prepared therefrom

Abstract

A method for manufacturing a poly(imide) prepolymer varnish includes combining a bisanhydride powder or organic diamine and a solvent to form a mixture, and adding an organic diamine or bisanhydride powder to the mixture to form a poly(imide) prepolymer. The method of manufacturing the varnish further includes at least one of adding an effective amount of a secondary or tertiary amine to solubilize the poly(imide) prepolymer powder, heating the mixture to a temperature effective to provide the varnish, or agitating the mixture to provide the varnish. The poly(imide) prepolymer varnish can have a residual organic diamine content of less than or equal to 1000 ppm. A poly(imide) polymer prepared from the prepolymer varnish is also disclosed.

1 . A method for the manufacture of a poly(imide) prepolymer varnish, the method comprising,
 combining a bisanhydride powder or an organic diamine and a solvent comprising a C 1-6  alcohol, water soluble ketone, water, or a combination comprising at least one of the foregoing to form a mixture; and   adding an organic diamine or a bisanhydride powder to the mixture under conditions effective to form a poly(imide) prepolymer, provided that when the bisanhydride powder is combined with the solvent, the organic diamine is added to the mixture to form the poly(imide) prepolymer, and when the organic diamine is combined with the solvent, the bisanhydride powder is added to the mixture to form the poly(imide) prepolymer;   wherein the method further comprises at least one of the following process steps:
 adding an effective amount of a secondary or tertiary amine to solubilize the poly(imide) prepolymer in the solvent; 
 heating the mixture comprising the poly(imide) prepolymer to a temperature effective to provide a varnish; and 
 agitating the mixture under conditions effective to provide a varnish; and 
   wherein the poly(imide) prepolymer varnish has a residual organic diamine content of less than or equal to 1000 ppm.   
     
     
         2 . The method of  claim 1 , wherein the method further comprises
 adding a secondary or tertiary amine to provide the varnish,   heating the mixture comprising the poly(imide) prepolymer to a temperature effective to provide a varnish.   
     
     
         3 . The method of  claim 1 , wherein the method further comprises
 agitating the mixture under conditions effective to provide a varnish, or   agitating the mixture under conditions effective to provide a varnish and heating the mixture to a temperature of greater than or equal to 25° C.   
     
     
         4 . The method of  claim 1 , wherein a secondary or tertiary amine is excluded from the varnish. 
     
     
         5 . The method of  claim 1 , wherein the solvent comprises acetone, methyl ethyl ketone, or a combination comprising at least one of the foregoing and water. 
     
     
         6 . The method of  claim 1 , wherein the C 1-6  alcohol comprises methanol, ethanol, n-propanol, isopropanol, or a combination comprising at least one of the foregoing. 
     
     
         7 . The method of  claim 1 , wherein
 combining the bisanhydride powder or the organic diamine and the solvent is at a temperature of 5 to 30° C.;   adding the organic diamine or the bisanhydride powder is at a temperature of 5 to 30° C.; and   wherein a reaction time sufficient to provide the poly(imide) prepolymer is greater than 5 minutes.   
     
     
         8 . The method of  claim 1 , further comprising adding
 an end-capping agent to the slurry;   a branching or crosslinking agent;   or both.   
     
     
         9 . A poly(imide) prepolymer varnish prepared according to the method of  claim 1 . 
     
     
         10 . A poly(imide) prepolymer varnish, comprising
 a poly(imide) prepolymer powder;   a secondary or tertiary amine; and   a solvent comprising water, a C 1-6  alcohol, a water soluble ketone, or a combination comprising at least one of the foregoing;   wherein the poly(imide) prepolymer varnish has a residual organic diamine content of less than or equal to 1000 ppm.   
     
     
         11 . A poly(imide) prepolymer varnish, comprising
 a poly(imide) prepolymer powder; and   a solvent comprising acetone and water;   wherein
 the poly(imide) prepolymer varnish has a residual organic diamine content of less than or equal to 1000 ppm; and 
 the prepolymer varnish excludes a secondary or tertiary amine. 
   
     
     
         12 . The poly(imide) prepolymer varnish of  claim 10 , wherein the secondary amine comprises dibutylamine, and the tertiary amine comprises triethylamine, dimethylethanolamine, or a combination comprising at least one of the foregoing. 
     
     
         13 . The poly(imide) prepolymer varnish of  claim 10 , wherein the poly(imide) prepolymer varnish comprises
 less than 1 wt % of a halogenated solvent;   less than or equal to 25 wt % of N-methyl pyrrolidone, dimethylacetamide, N,N-dimethyl formamide, tetrahydrofuran, sulfolane, anisole, cyclohexanone, cyclopentanone, dimethylsulfoxide, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 1-methoxy 2-propanol acetate, glycol ethers, glycol esters, or a combination comprising at least one of the foregoing;   or both.   
     
     
         14 . A method of making a poly(imide), the method comprising heating the poly(imide) prepolymer varnish of  claim 9  to a temperature of greater than 150° C. to provide the poly(imide). 
     
     
         15 . A method of making a prepreg, laminate, or composite, the method comprising
 contacting the poly(imide) prepolymer varnish of  claim 9  with a fiber, fabric, veil, or mat and optionally removing at least a portion of the solvent by heating to a temperature of 22 to 150° C.; and   heating to a temperature of greater than 150° C. to provide the prepreg, laminate or composite comprising the poly(imide);   wherein the poly(imide) has a weight average molecular weight of 5,000 to 200,000 grams per mole, and a polydispersity index of less than or equal to 3.