Papers Having High Average Specific Modulus and Ultimate Tensile Strength

Abstract

A paper comprising polymeric fibers and a binder, wherein the polymeric fibers comprise first fibers and second fibers, the first fibers comprising an aramid 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 second fibers comprising poly(para-phenylene terephthalate) homopolymer, and the binder comprising a third polymer that is either an aramid homopolymer or aramid copolymer; the paper having an ultimate tensile strength of 21 N-m/g or greater and average specific modulus of 4950 Pa-m 3 /g or greater.

1 . A paper comprising polymeric fibers and a binder, wherein the polymeric fibers comprise first fibers and second fibers,
 the first fibers comprising a first polymer, wherein the first polymer is an aramid 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 second fibers comprising poly(para-phenylene terephthalate) homopolymer, and the binder comprising a third polymer that is either an aramid homopolymer or aramid copolymer;   wherein the paper comprises 85 to 40 parts by weight polymeric fibers and 15 to 60 parts by weight binder, based on the combined weight of said polymeric fibers and said binder in the paper,   the polymeric fibers comprising 12.5 to 75 parts by weight first fibers and 25 to 87.5 parts by weight second fibers, based on the combined weight of said first and said second fibers in the polymeric fibers, and   wherein the paper has an ultimate tensile strength of 21 N-m/g or greater and average specific modulus of 4950 Pa-m 3 /g or greater.   
     
     
         2 . The paper of  claim 1  wherein the polymeric fibers comprise 12.5 to 60 parts by weight first fibers and 40 to 87.5 parts by weight second fibers, based on the combined weight of said first and said second fibers. 
     
     
         3 . The paper of  claim 2  wherein the polymeric fibers comprise 12.5 to 50 parts by weight first fibers and 50 to 87.5 parts by weight second fibers, based on the combined weight of said first and said second fibers. 
     
     
         4 . The paper of  claim 1  comprising 80 to 50 parts by weight of the polymeric fibers and 20 to 50 parts by weight of the binder, based on the combined weight of said polymeric fibers and said binder. 
     
     
         5 . The paper of  claim 1 , wherein the benzimidazole monomer of the first polymer is 5(6)-amino-2-(p-aminophenyl) benzimidazole. 
     
     
         6 . The paper of  claim 1 , wherein the para-oriented diamine monomer of the first polymer is paraphenylene diamine. 
     
     
         7 . The paper of  claim 1 , wherein the para-oriented aromatic acid monomer of the first polymer is terephthaloyl dichloride. 
     
     
         8 . The paper of  claim 1 , wherein the binder includes non-granular polymer fibrids that are fibrous, film-like or a mixture thereof. 
     
     
         9 . The paper of  claim 1 , wherein the third polymer is poly(meta-phenylene isophthalamide) homopolymer. 
     
     
         10 . The paper of  claim 1 , wherein the third polymer is an aramid copolymer having a structure derived from the reaction of para-oriented aromatic diamine monomer and benzimidazole monomer with a para-oriented aromatic diacid monomer. 
     
     
         11 . The paper of  claim 10 , wherein the third 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. 
     
     
         12 . The paper of  claim 1 , wherein the ultimate tensile strength is 22 N·m/g or greater. 
     
     
         13 . A process for making a paper, comprising the steps of
 a) forming an aqueous slurry comprising 85 to 40 parts by weight polymeric fibers and 15 to 60 parts by weight binder, based on the combined weight of said polymeric fibers and said binder,
 wherein the polymeric fibers comprise first fibers and second fibers,
 the first fibers comprising a first polymer, wherein the first polymer is an aramid 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 second fibers comprising poly(para-phenylene terephthalate) homopolymer, and 
 the binder comprising a third polymer that is either an aramid homopolymer or aramid copolymer; and 
 the polymeric fibers comprising 12.5 to 75 parts by weight first fibers and 25 to 87.5 parts by weight second fibers, based on the combined weight of said first and said second fibers; 
 
   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 (125 to 894 kg/cm);   
       to form a paper having an ultimate tensile strength of 21 N-m/g or greater and average specific modulus of 4950 Pa-m 3 /g or greater. 
     
     
         14 . The process of  claim 13 , wherein the polymeric fibers comprise 12.5 to 60 parts by weight first fibers and 40 to 87.5 parts by weight second fibers, based on the combined weight of said first and said second fibers. 
     
     
         15 . The process of  claim 14 , wherein the polymeric fibers comprise 12.5 to 50 parts by weight first fibers and 50 to 87.5 parts by weight second fibers, based on the combined weight of said first and said second fibers. 
     
     
         16 . The process of  claim 13  comprising 80 to 40 parts by weight of the polymeric fibers and 20 to 60 parts by weight of the binder, based on the combined weight of said polymeric fibers and said binder. 
     
     
         17 . The process of  claim 13 , 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. 
     
     
         18 . The process of  claim 13 , wherein the binder includes non-granular polymer fibrids that are fibrous, film-like or a mixture thereof. 
     
     
         19 . The process of  claim 13 , wherein the third polymer is poly(meta-phenylene isophthalamide) homopolymer. 
     
     
         20 . The process of  claim 13 , wherein the third polymer is an aramid copolymer having a structure derived from the reaction of para-oriented aromatic diamine monomer and benzimidazole monomer with a para-oriented aromatic diacid monomer. 
     
     
         21 . The process of  claim 20 , wherein the third 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. 
     
     
         22 . The process of  claim 13 , wherein step a) the first fibers have a 2 theta (2θ) x-ray diffraction angle peak of 25 (+/−0.5) degrees 
     
     
         23 . The process of  claim 13 , wherein step a) the first fibers have not been exposed to any environment of 260° C. or higher