Papers Having Low Density and High Average Specific Modulus

Abstract

A paper comprising polymeric fibers and polymeric binder, the polymeric fibers comprising a first polymer that is a copolymer having a structure derived from the reaction of para-oriented aromatic diamine monomer and benzimidazole monomer with a para-oriented aromatic diacid monomer, and the polymeric binder comprising a second polymer that is a copolymer having a structure derived from the reaction of para-oriented aromatic diamine monomer and benzimidazole monomer with a para-oriented aromatic diacid monomer, the paper having a density of 0.5 grams per cubic centimeter or less and an average specific modulus of 8500 Pa-m3/g or higher.

1 . A paper comprising polymeric fibers, and polymeric binder, the polymeric fibers comprising a first polymer and the polymeric binder comprising a second polymer,
 wherein the first polymer is a copolymer having a structure derived from the reaction of para-oriented aromatic diamine monomer and benzimidazole monomer with a para-oriented aromatic diacid monomer, and   wherein the second polymer is a copolymer having a structure derived from the reaction of para-oriented aromatic diamine monomer and benzimidazole monomer with a para-oriented aromatic diacid monomer,   the paper having an average specific modulus of 8500 Pa-m 3 /g or higher and a density of 0.50 grams per cubic centimeter or less.   
     
     
         2 . The paper of  claim 1 , wherein the benzimidazole monomer of the first polymer is 5(6)-amino-2-(p-aminophenyl) benzimidazole. 
     
     
         3 . The paper of  claim 1 , wherein the para-oriented diamine monomer of the first polymer is paraphenylene diamine. 
     
     
         4 . The paper of  claim 1 , wherein the para-oriented aromatic acid monomer of the first polymer is terephthaloyl dichloride. 
     
     
         5 . The paper of  claim 1 , wherein the benzimidazole monomer of the second polymer is 5(6)-amino-2-(p-aminophenyl) benzimidazole. 
     
     
         6 . The paper of  claim 1 , wherein the para-oriented diamine monomer of the second polymer is paraphenylene diamine. 
     
     
         7 . The paper of  claim 1 , wherein the para-oriented aromatic acid monomer of the second polymer is terephthaloyl dichloride. 
     
     
         8 . The paper of  claim 1 , wherein the first and second polymer are the same polymer. 
     
     
         9 . The paper of  claim 1  comprising 40 to 90 weight percent of the polymeric fibers comprising the first polymer and 10 to 60 weight percent of the polymeric binder comprising the second polymer, based on the combined weight of said polymeric fibers and said polymeric binder. 
     
     
         10 . The paper of  claim 1 , wherein the polymeric binder includes non-granular polymer fibrids that are fibrous, film-like or a mixture thereof, made from the second polymer. 
     
     
         11 . The paper of  claim 1 , wherein the paper has a 2 theta (2θ) x-ray diffraction angle peak of 20.2 (+/−0.5) degrees, the integrated intensity of said x-ray diffraction angle peak being greater than 4 percent of the total diffraction pattern intensity, after background subtraction. 
     
     
         12 . The paper of  claim 1 , wherein voids in the paper comprise a matrix resin. 
     
     
         13 . The paper of  claim 12 , wherein the matrix resin is epoxy, phenolic, polyurea, polyurethane, melamine formaldehyde, polyester, polyvinyl acetate, polyacrylonitrile, alkyd, polyimide, diallyl phthalate, or bismaleimide-triazine. 
     
     
         14 . A process for making a paper, comprising the steps of
 a) forming an aqueous slurry comprising polymeric fibers comprising a first polymer and polymeric binder comprising a second polymer,
 wherein the first polymer is a copolymer having a structure derived from the reaction of para-oriented aromatic diamine monomer and benzimidazole monomer with a para-oriented aromatic diacid monomer, and the polymeric fibers have a 2 theta (2θ) x-ray diffraction angle peak of 20.2 (+/−0.5) degrees, and 
 wherein the second polymer is a copolymer having a structure derived from the reaction of para-oriented aromatic diamine monomer and benzimidazole monomer with a para-oriented aromatic diacid monomer; 
   b) removing water from the slurry on a paper machine to form a wet paper composition;   c) drying the wet paper composition to form a dried sheet; and   d) thermally consolidating the dried sheet in one or more steps between nipped rolls heated to a surface temperature of 260° C. or more, using a nip pressure of 700 to 5000 lbs./inch (268 to 894 kg/cm);   to form a paper having an average specific modulus of 8500 Pa-m 3 /g or higher and a density of 0.50 grams per cubic centimeter or less.   
     
     
         15 . The process of  claim 14 , wherein the first polymer comprises benzimidazole monomer that is 5(6)-amino-2-(p-aminophenyl) benzimidazole, para-oriented diamine monomer that is paraphenylene diamine, and para-oriented aromatic acid monomer that is terephthaloyl dichloride. 
     
     
         16 . The process of  claim 14 , wherein the second polymer comprises benzimidazole monomer that is 5(6)-amino-2-(p-aminophenyl) benzimidazole, para-oriented diamine monomer that is paraphenylene diamine, and para-oriented aromatic acid monomer that is terephthaloyl dichloride. 
     
     
         17 . The process of  claim 14 , wherein the first polymer comprises benzimidazole monomer that is 5(6)-amino-2-(p-aminophenyl) benzimidazole, para-oriented diamine monomer that is paraphenylene diamine, and para-oriented aromatic acid monomer that is terephthaloyl dichloride, and wherein the second polymer comprises benzimidazole monomer that is 5(6)-amino-2-(p-aminophenyl) benzimidazole, para-oriented diamine monomer that is paraphenylene diamine, and para-oriented aromatic acid monomer that is terephthaloyl dichloride. 
     
     
         18 . The process of  claim 14 , wherein the first and second polymer are the same polymer. 
     
     
         19 . The process of  claim 14  wherein in step a) the slurry comprises 40 to 90 weight percent of the said polymeric fibers comprising the first polymer and 10 to 60 weight percent of said polymeric binder comprising a second polymer, based on the combined weight of the said polymeric fibers and said polymeric binder. 
     
     
         20 . The process of  claim 14 , wherein the polymeric binder includes non-granular polymer fibrids that are fibrous, film-like or a mixture thereof, made from the second polymer. 
     
     
         21 . The process of  claim 14 , wherein in step a), the polymeric fibers have been exposed to an environment of 260° C. or higher. 
     
     
         22 . The process of  claim 14 , wherein the paper has a 2 theta (2θ) x-ray diffraction angle peak of 20.2 (+/−0.5) degrees, the integrated intensity of said x-ray diffraction angle peak being more than 4 percent of the total diffraction pattern intensity, after background subtraction. 
     
     
         23 . The process of  claim 14 , further comprising impregnating the paper with a matrix resin of epoxy, phenolic, polyurea, polyurethane, melamine formaldehyde, polyester, polyvinyl acetate, polyacrylonitrile, alkyd, polyimide, diallyl phthalate, or bismaleimide-triazine.