Fibrous products and methods of manufacture

Abstract

Fibrous materials made from multiple populations of fibers, and compositions related to preparing such, are disclosed. In some instances, fiber populations can have different native surfaces, in which at least one of the populations can be surface modified, for example by the use of a polycation (e.g., a polyamine), secondary polymers, complementary polymers, and/or other agents. These populations can be combined to form a fibrous composition, where the surface treatments can enhance properties of the end product. Populations of fibers can also have other physically varying characteristics (e.g., shapes and sizes). Such compositions can be utilized in a variety of applications such as paper products, filters, fire-retardant fibrous products, protein adsorbing fibrous materials, and fibrous sheets having conducting properties. Methods of preparing portions or the entirety of such fibrous materials are also disclosed.

1 . A fibrous composition of mixed fibers, comprising:
 a first population of fibers;   a second population of fibers having native surface characteristics differing from native surface characteristics of the first population of fibers,   at least one population of fibers being surface modified by a polycation, the first and second population of fibers being mixed together in the form of a porous composition.   
     
     
         2 . The composition of  claim 1 , wherein the fibrous composition comprises a sheet structure. 
     
     
         3 . The composition of any preceding  claim 1 , wherein the polycation comprises a polyamine. 
     
     
         4 . The composition of  claim 1 , wherein at least one surface modified population of fibers comprises synthetic fibers. 
     
     
         5 . The composition of  claim 1 , wherein at least one surface modified population of fibers comprises fibers exhibiting a native hydrophobic surface. 
     
     
         6 . The composition of  claim 5 , wherein the native hydrophobic surface is surface modified to a hydrophilic surface. 
     
     
         7 . The composition of  claim 1 , wherein at least one population of fibers comprises natural fibers. 
     
     
         8 . The composition of  claim 1 , wherein at least one population of fibers comprises at least one of microfibers and larger fibers. 
     
     
         9 . The composition of  claim 1 , wherein at least one population of fibers comprises fibers having dissimilar sizes. 
     
     
         10 . The composition of  claim 1 , wherein the polycation is bound to at least one fiber using a coupling agent. 
     
     
         11 . The composition of  claim 1 , wherein at least one population of surface modified fibers is attached to the polycation by at least one of electrostatic interactions, covalent bonding, hydrogen bonding, and hydrophobic interactions. 
     
     
         12 . The composition of  claim 1 , wherein the polycation couples at least two fibers together. 
     
     
         13 . The composition of  claim 1 , further comprising:
 a complementary polymer capable of attractively interacting with the polycation.   
     
     
         14 . The composition of  claim 13 , wherein the complementary polymer comprises at least one of a pectin, xanthan gum, carboxymethyl cellulose, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyethylene glycol, polymers derived from maleic anhydride, and copolymer having at least one segment comprising any of the aforementioned polymers. 
     
     
         15 . The composition of  claim 13 , wherein the complementary polymer comprises at least one of an epoxide, an anhydride, a carboxylic acid, and an isocyanate. 
     
     
         16 . The composition of  claim 1 , further comprising a wet strength component. 
     
     
         17 . The composition of  claim 16 , wherein the wet-strength component comprises at least one of a melamine-formaldehyde resin, a urea-formaldehyde resin, and an epoxidized polyamine-polyamide resin. 
     
     
         18 . The composition of  claim 1 , wherein the polycations comprises polycations modified with hydrophobic side groups. 
     
     
         19 . The composition of  claim 1 , wherein at least one surface modified population of fibers comprises a polysaccharide coupled to at least one of the fibers. 
     
     
         20 . The composition of  claim 1 , wherein at least one surface modified population of fibers comprises synthetic fibers having a cellulose-based material coupled thereto. 
     
     
         21 . The composition of  claim 19 , further comprising: a crosslinker for coupling the surface modification to at least one of a fiber and another portion of the surface modification. 
     
     
         22 . The composition of  claim 1 , wherein at least one population of fibers comprises at least one of a fire-retardant material, an electrically conductive material, a nanofibrillated cellulose-based material. 
     
     
         23 . The composition of  claim 1 , wherein at least one surface modified population of fibers exhibits protein adsorption resistance relative to a native surface of the surface modified population of fibers. 
     
     
         24 . The composition of  claim 1 , wherein the composition is at least a portion of a filter paper. 
     
     
         25 . A method for forming a mixed fiber composition, comprising:
 attaching polycations to a first population of fibers;   providing a second population of fibers having native surface characteristics differing from native surface characteristics of the first population of fibers;   forming a precursor fiber composition comprising the first population of fibers and the second population of fibers; and   creating a sheet structure from the precursor fiber composition.   
     
     
         26 . The method of  claim 25 , wherein the step of attaching polycations comprises precipitating the polycations onto the first population of fibers. 
     
     
         27 . The method of  claim 26 , further comprising:
 attaching a coupling agent to the polycations.   
     
     
         28 . The method of  claim 25 , further comprising:
 adding a wet strength component to the fiber composition.   
     
     
         29 . The method of  claim 28 , wherein the step of adding the wet strength component comprises adding the wet strength component after mixing the first population of fibers and the second population of fibers together. 
     
     
         30 . The method of  claim 25 , further comprising:
 adding a complementary polymer having an anionic portion to the first population of fibers; and   attaching the complementary polymer to the at least one of the polycations.   
     
     
         31 . The method of  claim 25 , wherein at least one population of fibers comprises synthetic fibers and at least one population of fibers comprises natural fibers.