Acoustical gypsum board for ceiling panel

Abstract

Low density acoustical gypsum boards having a perforated cover sheet that have good sound absorption properties and are generally clear of falling gypsum dust. The invention optionally provides a cover sheet having a pattern producing a textured visual effect particularly when viewed from a distance. The acoustical gypsum boards can be produced on modified existing gypsum board lines.

1 . A gypsum-based acoustical board having a set gypsum core disposed between two substantially parallel cover sheets comprising: 
 a set gypsum core made from a core formulation having about 75% to about 90% by weight stucco based on the total weight of the core formulation, about 0 to about 15% by weight perlite based on the total weight of the core formulation, about 2% to about 12% by weight paper fiber based on the total weight of the core formulation, and about 0.5% to about 5% by weight starch based on the total weight of the core formulation; and    a multiplicity of sound-absorbing perforations extending through a cover sheet and into the set gypsum core.    
   
   
       2 . The acoustical board of  claim 1 , wherein the core formulation includes stucco in an amount from about 80% to about 85% by weight based on the weight of the core formulation, perlite in an amount from about 5% to about 8% by weight based on the weight of the core formulation, paper fiber in an amount from about 6% to about 10% by weight based on the weight of the core formulation, and starch in an amount from about 0.5% to about 2% by weight based on the weight of the core formulation.  
   
   
       3 . The acoustical board of  claim 1 , wherein the perlite has a density of from about 3.0 pcf to about 5.0 pcf.  
   
   
       4 . The acoustical board of  claim 1 , wherein the paper fiber is hydropulp.  
   
   
       5 . The acoustical board of  claim 1 , wherein the starch is pregelatinized corn starch.  
   
   
       6 . The acoustical board of  claim 1 , including cover sheets comprising a face paper and a back paper, the perforations extending through the face paper and into but not through the set gypsum core.  
   
   
       7 . The acoustical board of  claim 6 , wherein the face paper has a pattern that creates a visual appearance of a texture when viewed from a distance.  
   
   
       8 . The acoustical board of  claim 1 , wherein the perforations have a diameter of about 0.062 inch and are present at about 1800 pins per square foot.  
   
   
       9 . The acoustical board of  claim 1 , wherein the board is about 0.54 inch thick and the perforations are from about ¼ inch to about ½ inch deep.  
   
   
       10 . The acoustical board of  claim 1 , wherein the board density is from about 16 pcf to about 20 pcf.  
   
   
       11 . The acoustical board of  claim 1 , wherein the board density is from about 16 pcf to about 17 pcf.  
   
   
       12 . The acoustical board of  claim 1  having an NRC value from about 0.50 to about 0.65.  
   
   
       13 . The acoustical board of  claim 1  wherein the perlite in the core formulation is present at a weight ratio of perlite to paper fiber of about 1:1.1 to about 1:2.  
   
   
       14 . The acoustical board of  claim 1  wherein the perlite in the core formulation is present at a weight ratio of perlite to paper fiber of about 1:1.4 to about 1:1.6.  
   
   
       15 . A gypsum-based acoustical board having a set gypsum core disposed between a face paper and a back paper comprising: 
 a set gypsum core made from a core formulation having about 75% to about 90% by weight stucco based on the total weight of the core formulation, about 0 to about 15% by weight perlite based on the total weight of the core formulation, about 2% to about 12% by weight paper fiber based on the total weight of the core formulation, and about 0.5% to about 5% by weight starch based on the total weight of the core formulation; and    a multiplicity of sound-absorbing perforations extending through the face paper and into but not through the set gypsum core.    
   
   
       16 . A method of making gypsum-based acoustical board, comprising the steps of: 
 (a) mixing a slurry of water, stucco in an amount from about 75% to about 90% by weight based on the total solids weight, perlite in an amount up to about 15% by weight based on the total solids weight, paper fiber in an amount from about 2% to about 12% by weight based on the total solids weight, and a starch in an amount from about 0.5% to about 5% by weight based on the total solids weight;    (b) adding a soap foam having a density of about 10 pcf to the slurry;    (c) depositing the slurry on a first cover sheet;    (d) maintaining the slurry under conditions sufficient for the stucco to form a set gypsum core;    (e) placing a second cover sheet over the set gypsum core to form an acoustical board;    (f) drying the formed board;    (g) cutting the dried board; and    (h) perforating one of the cover sheets of the dried board in such a manner that the perforations extend into but not through the set gypsum core.    
   
   
       17 . The method of  claim 16 , further comprising applying a pattern on the second cover sheet prior to step (g).  
   
   
       18 . A method of making gypsum-based acoustical board, comprising the steps of: 
 (a) mixing a slurry comprising water, stucco in an amount from about 75% to about 90% by weight based on the total solids weight, perlite in an amount up to about 15% by weight based on the total solids weight, paper fiber in an amount from about 2% to about 12% by weight based on the total solids weight, and a starch in an amount from about 0.5% to about 5% by weight based on the total solids weight;    (b) adding a soap foam having a density of about 10 pcf to the slurry;    (c) depositing the slurry on a first cover sheet;    (d) maintaining the slurry under conditions sufficient for the stucco to form a set gypsum core;    (e) placing a second cover sheet over the set gypsum core to form an acoustical board;    (f) drying the formed board to constant weight to produce a dried board having a density of not more than about 20 pcf;    (g) cutting the dried board; and    (h) perforating one of the cover sheets of the dried board using pins with a pin count of about 1800 pins per square foot and a pin diameter of about 0.062 inch, in such a manner that the perforations extend into but not through the set gypsum core.    
   
   
       19 . The method of  claim 18 , further comprising applying a pattern on the second cover sheet prior to step (g).