Automotive dash insulators containing viscoelastic foams

Abstract

Sound insulating systems including viscoelastic foams are described. The sound insulating system includes a sound-absorbing layer. The sound-absorbing layer can include viscoelastic foams. An optional barrier layer is adjacent to the sound-absorbing layer. Additionally, an optional substrate layer is adjacent to the sound-absorbing layer, and is spaced and opposed from the optional barrier layer. The sound insulating system is particularly well adapted to be employed as vehicle dashmats.

1 . A sound insulating system, comprising: 
 a sound-absorbing layer including an absorption coefficient in the range of about 0.2 to about 1.0, and a damping loss factor in the range of about 0.3 to about 2.0.    
   
   
       2 . A sound insulating system as set forth in  claim 1  wherein said sound-absorbing layer comprises viscoelastic foam.  
   
   
       3 . A sound insulating system as set forth in  claim 2  wherein said viscoelastic foam has a damping loss factor in the range of about 0.4 to 1.6.  
   
   
       4 . A sound insulating system as set forth in  claim 3  wherein said viscoelastic foam has an elastic modulus in the range of about 4×10 3  Pa to about 1×10 6  Pa.  
   
   
       5 . A sound insulating system as set forth in  claim 4  further comprising a barrier layer secured to said viscoelastic foam, said barrier layer substantially impermeable to fluid flow therethrough.  
   
   
       6 . A sound insulating system as set forth in  claim 5  wherein said absorption coefficient of said viscoelastic foam is preferably in the range of about 0.7 to about 1 at frequencies in the range of about 1000 Hz to about 6000 Hz.  
   
   
       7 . A sound insulating system as set forth in  claim 6  further comprising a substrate, said viscoelastic foam secured to said substrate.  
   
   
       8 . A sound insulating system as set forth in  claim 7  wherein said substrate is a metal structure on a vehicle.  
   
   
       9 . A sound insulating system, comprising: 
 a sound-absorbing layer including an absorption coefficient in the range of about 0.2 to about 1.0, and a damping loss factor in the range of about 0.3 to about 2.0; and    a barrier layer substantially impermeable to fluid flow therethrough connected to said sound-absorbing layer.    
   
   
       10 . A sound insulating system as set forth in  claim 1  wherein said sound-absorbing layer comprises viscoelastic foam.  
   
   
       11 . A sound insulating system as set forth in  claim 10  wherein said viscoelastic foam has a damping loss factor in the range of about 0.4 to 1.6.  
   
   
       12 . A sound insulating system as set forth in  claim 11  wherein said viscoelastic foam has an elastic modulus in the range of about 4×10 3  Pa to about 1×10 6  Pa.  
   
   
       13 . A sound insulating system as set forth in  claim 12  wherein said absorption coefficient of said viscoelastic foam is preferably in the range of about 0.7 to about 1 at frequencies in the range of about 1000 Hz to about 6000 Hz.  
   
   
       14 . A sound insulating system as set forth in  claim 13  further comprising a substrate, said viscoelastic foam secured to said substrate.  
   
   
       15 . A sound insulating system as set forth in  claim 14  wherein said substrate is a metal structure on a vehicle.  
   
   
       16 . A sound insulating system, comprising: 
 a sound-absorbing layer comprising a viscoelastic foam including an absorption coefficient in the range of about 0.7 to about 1 at frequencies in the range of about 1000 Hz to about 6000 Hz, and a damping loss factor in the range of about 0.4 to 1.6; and    a barrier layer substantially impermeable to fluid flow therethrough connected to said viscoelastic foam.    
   
   
       17 . A sound insulating system as set forth in  claim 16  wherein said viscoelastic foam has an elastic modulus in the range of about 4×10 3  Pa to about 1×10 6  Pa.  
   
   
       18 . A sound insulating system as set forth in  claim 17  further comprising a substrate, said viscoelastic foam secured to said substrate.  
   
   
       19 . A sound insulating system as set forth in  claim 18  wherein said substrate is a metal structure on a vehicle.