Wet-formed mat applications for cement backerboards

Abstract

A wet-formed permeable mat composed of wet use chopped strands (WUCS), chopped roving, and potentially unidirectional roving coupled with an alkaline resistant binder are combined to create an randomly oriented open mat structure with a high degree of openness that can be used in cement backerboard applications. The cement backerboard that is subsequently formed from the wet-formed permeable mat has lower binder content, superior decorative finish, and better permeability control than known glass scrim systems and can be produced in a single continuous step.

What is claimed is:  
     
         1 . A wet formed permeable mat for use in a cement backerboard comprising: 
 a randomly oriented open mesh glass filament network comprising approximately a mixture of a plurality of wet use chop strands and a plurality of dry chop glass fiber strands, wherein said plurality of wet use chop strands and said plurality of dry chop glass fiber strands each have lengths between approximately 0.75 and 1.5 inches and wherein the ratio by weight of said plurality of wet use chop strands and said plurality of dry use chop strands within said mixture is between approximately 3:1 and 1:3; and    an alkaline resistant binder.    
     
     
         2 . The permeable mat of  claim 1 , wherein said randomly oriented open mesh glass filament network further comprises a plurality of unidirectional rovings, said unidirectional rovings comprising approximately 20 to 50 percent by weight of said randomly oriented open mesh glass filament network.  
     
     
         3 . The permeable mat of  claim 1 , wherein said alkaline resistant binder comprises between approximately 20 and 50 percent by weight of the wet formed permeable mat.  
     
     
         4 . The permeable mat of  claim 1 , wherein said alkaline resistant binder is selected from the group consisting of phenolic binders, melamine binders, acrylic binders, styrene-acrylate binders, styrene butadiene binders, and ethylene vinyl acetate binders.  
     
     
         5 . The permeable mat of  claim 1 , wherein said alkaline resistant binder comprises Borden Chemical's 5901 phenolic binder.  
     
     
         6 . The permeable mat of  claim 1 , wherein said alkaline resistant binder comprises Rohm and Haas' GL618 acrylic copolymer binder.  
     
     
         7 . A method for forming a wet formed permeable mat for use in reinforced cement backerboards comprising: 
 forming a thick slurry of a whitewater chemical dispersion having a plurality of wet use chop strands and a plurality of dry chop glass fiber strands;    introducing said thick slurry to a thin stock stream slurry to form a lower consistency slurry;    introducing said lower consistency slurry to a former,    aligning said plurality of wet use chop strands and said plurality of dry chop glass fiber strands within said former to form a web;    partially drying said web;    introducing an alkaline resistant binder to said web; and    drying and curing said alkaline resistant binder and said web to form the wet formed permeable mat.    
     
     
         8 . The method of  claim 7 , wherein forming a thick slurry comprises forming a thick slurry comprising a cationic dispersant, an anionic viscosity modifier, a defoamer, a biocide, a plurality of wet use chop strands and a plurality of dry chop glass fiber strands.  
     
     
         9 . The method of  claim 8 , wherein forming a thick slurry of a whitewater chemical dispersion comprises: 
 (a) introducing a cationic dispersant to a tank under agitation;    (b) introducing a weight mixture of a plurality of wet use chop strands and a plurality of dry chop glass fiber strands to (a), wherein the ratio by weight of said plurality of wet use chop strands and said plurality of dry use chop strands within said mixture is between approximately 3:1 and 1:3;    (c) introducing a defoamer to (b);    (d) introducing an anionic viscosity modifier to (c).    
     
     
         10 . The method of  claim 8 , wherein said anionic viscosity modifier is selected from the group consisting of a polyacrylamide viscosity modifier, a hydroxyethyl cellulose viscosity modifier, and a polyamine viscosity modifier.  
     
     
         11 . The method of  claim 10 , wherein said polyacrylamide viscosity modifier is selected from the group consisting of Nalco 7768, Magnifloc 1886A, HyChem AE 874.  
     
     
         12 . The method of  claim 8 , wherein said cationic dispersant is selected from the group consisting of an ethoxylated alkylamine dispersant, an amine oxide dispersant, and a polyethyoxylated derivative of an amide condensated fatty acid dispersant.  
     
     
         13 . The method of  claim 12 , wherein said ethoxylated alkylamine dispersant is selected from the group consisting of Nalco 8493, Schercopol DS-140, and Rhodameen VP532.  
     
     
         14 . The method of  claim 8 , wherein said defoamer is selected from the group consisting of Nalco PP04-3840 and Nopco NXZ.  
     
     
         15 . The method of  claim 8 , wherein forming a thick slurry comprises forming a thick slurry of a whitewater chemical dispersion having a plurality of wet use chop strands, a plurality of dry chop glass fiber strands and a plurality of unidirectional rovings.  
     
     
         16 . The method of  claim 15 , wherein forming a thick slurry comprises forming a thick slurry of a whitewater chemical dispersion, wherein forming a thick slurry comprises: 
 (a) introducing a cationic dispersant to a tank under agitation;    (b) introducing a mixture of a plurality of wet use chop strands and a plurality of dry chop glass fiber strands to (a), wherein the ratio by weight of said plurality of wet use chop strands and said plurality of dry use chop strands within said mixture is between approximately 3:1 and 1:3;    (c) introducing a plurality of unidirectional rovings to (a), wherein said plurality of unidirectional rovings comprise between approximately 20 and 50 percent of the total weight of said mixture and said plurality of unidirectional rovings;    (d) introducing a defoamer to (c);    (e) introducing an anionic viscosity modifier to (d).    
     
     
         17 . The method of  claim 15 , wherein said anionic viscosity modifier is selected from the group consisting of a polyacrylamide viscosity modifier, a hydroxyethyl cellulose viscosity modifier, and a polyamine viscosity modifier.  
     
     
         18 . The method of  claim 17 , wherein said polyacrylamide viscosity modifier is selected from the group consisting of Nalco 7768, Magnifloc 1886A, HyChem AE 874.  
     
     
         19 . The method of  claim 15 , wherein said cationic dispersant is selected from the group consisting of an ethoxylated alkylamine dispersant, an amine oxide dispersant, and a polyethyoxylated derivative of an amide condensated fatty acid dispersant.  
     
     
         20 . The method of  claim 19 , wherein said ethoxylated alkylamine dispersant is selected from the group consisting of Nalco 8493, Schercopol DS-140, and Rhodameen VP532.  
     
     
         21 . The method of  claim 15 , wherein said defoamer is selected from the group consisting of Nalco PP04-3840 and Nopco NXZ.  
     
     
         22 . A method for making a cement backerboard comprising: 
 forming a wet formed permeable mat, said wet formed permeable mat comprising a randomly oriented open mesh glass filament network and an alkaline resistant binder, wherein said randomly oriented open mesh glass filament network has approximately a mixture of a plurality of wet use chop strands and a plurality of dry chop glass fiber strands each have lengths between approximately 0.75 and 1.5 inches and wherein the ratio by weight of said plurality of wet use chop strands and said plurality of dry use chop strands within said mixture is between approximately 3:1 and 1:3;    introducing a first layer of said wet formed permeable mat to a form;    introducing a first amount of a cement slurry onto said first layer sufficient to cover said first layer;    introducing a layer of a core material onto said first amount of said cement slurry sufficient to cover said first amount of said cement slurry;    introducing a second layer of said wet formed permeable mat onto said layer of said core material;    introducing a second amount of said cement slurry onto said second layer sufficient to cover said first amount;    curing said first amount and said second amount of cement slurry.    
     
     
         23 . The method of  claim 22 , wherein forming a wet-formed permeable mat comprises: 
 forming a thick slurry of a whitewater chemical dispersion having a plurality of wet use chop strands and a plurality of dry chop glass fiber strands;    introducing said thick slurry to a thin stock stream slurry to form a lower consistency slurry;    introducing said lower consistency slurry to a former,    aligning said plurality of wet use chop strands and said plurality of dry chop glass fiber strands within said former to form a web;    partially drying said web;    introducing an alkaline resistant binder to said web; and    drying and curing said alkaline resistant binder and said web to form the wet formed permeable mat.    
     
     
         24 . The method of  claim 23 , wherein forming a thick slurry comprises forming a thick slurry comprising a cationic dispersant, an anionic viscosity modifier, a defoamer, a biocide, a plurality of wet use chop strands and a plurality of dry chop glass fiber strands.  
     
     
         25 . The method of  claim 24 , wherein forming a thick slurry of a whitewater chemical dispersion comprises: 
 (a) introducing a cationic dispersant to a tank under agitation;    (b) introducing a mixture of a plurality of wet use chop strands and a plurality of dry chop glass fiber strands to (a), wherein the ratio by weight of said plurality of wet use chop strands and said plurality of dry use chop strands within said mixture is between approximately 3:1 and 1:3;    (c) introducing a defoamer to (b);    (d) introducing an anionic viscosity modifier to (c).    
     
     
         26 . The method of  claim 23 , wherein said randomly oriented open mesh glass filament network further comprises a plurality of unidirectional rovings, said plurality of unidirectional rovings comprising approximately 20 to 50 weight percent of said randomly oriented open mesh glass filament network.  
     
     
         27 . The method of  claim 26 , wherein forming a thick slurry comprises forming a thick slurry of a whitewater chemical dispersion having a plurality of wet use chop strands, a plurality of dry chop glass fiber strands and a plurality of unidirectional rovings.  
     
     
         28 . The method of  claim 27 , wherein forming a thick slurry comprises forming a thick slurry comprising a cationic dispersant, an anionic viscosity modifier, a defoamer, a biocide, a plurality of wet use chop strands, a plurality of unidirectional rovings and a plurality of dry chop glass fiber strands.  
     
     
         29 . The method of  claim 28 , wherein forming a thick slurry comprises forming a thick slurry of a whitewater dispersion, wherein forming a thick slurry comprises: 
 (a) introducing a cationic dispersant to a tank under agitation;    (b) introducing a mixture of a plurality of wet use chop strands and a plurality of dry chop glass fiber strands to (a), wherein the ratio by weight of said plurality of wet use chop strands and said plurality of dry use chop strands within said mixture is between approximately 3:1 and 1:3;    (c) introducing a plurality of unidirectional rovings to (a), wherein said plurality of unidirectional rovings comprise between approximately 20 and 25 percent of the total weight of said mixture and said plurality of unidirectional rovings;    (d) introducing a defoamer to (c);    (e) introducing an anionic viscosity modifier to (d).