Fibrous material having densified surface for improved air flow resistance and method of making

Abstract

The present invention provides a fibrous veil having a plurality of densified portions formed thereon for improved airflow resistance. The airflow resistance may be tuned to meet the needs of a particular application by selecting the size, density and location of the densified portions. The veil may be used independently or in combination with other sound control materials. The present invention also provides a fibrous blanket having a plurality of densified portions formed on one or both major surfaces thereof for improved airflow resistance. The airflow resistance may be tuned to meet the needs of a particular application by selecting the size and density of the densified portions. A method of manufacturing the materials of the present invention by applying heat and/or pressure to portions of the material is also presented.

1 . A patterned acoustical web, comprising: 
 a fibrous web having a plurality of areas of a first density formed thereon and at least one area of a second density formed thereon, wherein the combination of the first density and the second density form a web having a predetermined acoustical impedance.    
     
     
         2 . The patterned acoustical web of  claim 1 , wherein said first density is greater than said second density.  
     
     
         3 . The patterned acoustical web of  claim 1 , wherein said second density is approximately equal to a density of the fibrous web prior to densification.  
     
     
         4 . The patterned acoustical web of  claim 1 , wherein the fibrous web is formed of a material having a material density and said first density is equal to at least 75% of the material density.  
     
     
         5 . The patterned acoustical web of  claim 1 , wherein said first density is greater than said second density.  
     
     
         6 . The patterned acoustical web of  claim 1 , wherein said acoustical impedance has a value between about 300 and 3500 Rayls.  
     
     
         7 . The patterned acoustical web of  claim 6 , wherein said acoustical impedance has a value between about 1300 and 3500 Rayls.  
     
     
         8 . The patterned acoustical web of  claim 1 , wherein said second density is greater than said first density.  
     
     
         9 . The patterned acoustical web of  claim 1 , wherein the area the first density is between about 40 and 90 percent of the surface area of the fibrous web.  
     
     
         10 . The patterned acoustical web of  claim 1 , wherein said densified area extends from a first major surface of the fibrous web to a second major surface of the fibrous web.  
     
     
         11 . A lofted fibrous acoustical insulation product, comprising: 
 a lofted fibrous acoustical material having formed on the surface thereof, a plurality of areas of a first density; and at least one area of a second density, wherein acoustical material has an acoustical impedance greater than about 300 Rayls.    
     
     
         12 . The fibrous acoustical insulation product of  claim 11 , wherein said first density is greater than said second density.  
     
     
         13 . The fibrous acoustical insulation product of  claim 11 , wherein said first density is greater than said second density.  
     
     
         14 . The fibrous acoustical insulation product of  claim 11 , further comprising at least on additional layer of an acoustical material.  
     
     
         15 . The fibrous acoustical insulation product of  claim 14 , wherein said acoustical impedance has a value of about 500 to 3500 Rayls.  
     
     
         16 . The fibrous acoustical insulation product of  claim 11 , wherein area of a first density is between about 40 and 90 percent of the surface area of the fibrous web.  
     
     
         17 . A method of manufacturing an acoustical product comprising the steps of: 
 providing a fibrous material;    densifying at least 40% of the surface of said fibrous material; and    forming a patterned densified surface, to provide an acoustical product having acoustical impedance has a value greater than about 300 Rayls.    
     
     
         18 . The method of  claim 17 , wherein said acoustical impedance has a value between about 300 and 3500 Rayls.  
     
     
         19 . The method of  claim 18 , wherein said acoustical impedance is between 1300 and 3500 Rayls.  
     
     
         20 . The method of  claim 17 , wherein said acoustical product includes a substantially undensified bulk material underlying said patterned densified surface.