Viscoelastic plastic interlayer for vibro-acoustic damping and glazing comprising such an interlayer

Abstract

A viscoelastic plastic interlayer intended to be incorporated between two glass sheets to form a laminated glazing with vibro-acoustic damping properties, the interlayer comprising at least one layer made of viscoelastic plastic with vibro-acoustic damping properties, the interlayer being such that the resonant frequency f 2 of the second resonance mode of a laminated glazing bar with a surface area of 25 mm×300 mm composed of two glass sheets each 2.1 mm thick, between which is incorporated the interlayer, determined by measuring the mechanical impedance (MIM) at 20° C. according to standard ISO 16940, is between 760 Hz and 1000 Hz and the loss factor r 12 of the second resonance mode of the same bar, determined by MIM under the same conditions, is greater than or equal to 0.25.

1 . A viscoelastic plastic interlayer to be incorporated between two glass sheets to form a laminated glazing with vibro-acoustic damping properties, the interlayer comprising at least one layer made of viscoelastic plastic with vibro-acoustic damping properties, the interlayer being such that the resonant frequency f 2  of the second resonance mode of a laminated glazing bar with a surface area of 25 mm×300 mm composed of two glass sheets each 2.1 mm thick, between which is incorporated the interlayer, determined by measuring the mechanical impedance (MIM) at 20° C. according to standard ISO 16940, is between 760 Hz and 1000 Hz and the loss factor η 2  of the second resonance mode of the same bar, determined by MIM under the same conditions, is greater than or equal to 0.25. 
     
     
         2 . The interlayer according to  claim 1 , in which the layer is based on polyvinyl butyral and plasticizer. 
     
     
         3 . The interlayer according to  claim 1 , in which the resonant frequency f 2  is between 800 and 900 Hz and preferably between 800 Hz and 850 Hz. 
     
     
         4 . The interlayer according to  claim 1 , in which the loss factor η 2  is greater than 0.30. 
     
     
         5 . The interlayer according to  claim 1 , also comprising two outer layers made of standard PVB, the layer being between the two outer layers. 
     
     
         6 . The interlayer according to  claim 1 , in which the measurement of the mechanical impedance is performed at least one month after assembly of the laminated glazing bar, the laminated glazing bar having itself been assembled at least one month after the manufacture of the interlayer. 
     
     
         7 . A glazing comprising:
 a glass sheet between 0.5 mm and 2.6 mm thick,   a glass sheet between 0.5 mm and 1.6 mm thick,   an interlayer according to  claim 1 , the interlayer being between the glass sheets,   in which the total thickness of the glass sheets is strictly less than 3.7 mm.   
     
     
         8 . A motor vehicle comprising glazing according to  claim 7 , the glass sheet between 0.5 mm and 2.6 mm thick being turned facing the exterior of the vehicle and the glass sheet between 0.5 mm and 1.6 mm thick being turned facing the interior of the vehicle. 
     
     
         9 . A motor vehicle windscreen comprising a glazing according to  claim 7 .