Laminated glazing material

Abstract

A laminated glazing material with properties of acoustic insulation and mechanical strength. The laminated glazing material including two glass sheets and a single-ply intermediate layer of a thickness having the form of a polymer film. The thickness of the intermediate layer being defined as a function of a variable which is specific to the material, and which defines the critical energy value of the intermediate layer and is representative of the energy necessary for propagation of a crack initiated in the intermediate layer.

What is claimed as new and desired to be secured by Letters Patent of the United States is:  
     
         1 . A laminated glazing material with properties of acoustic insulation and mechanical strength, said glazing material comprising two glass sheets and a single-ply intermediate layer in the form of a polymeric film and having a thickness, wherein the thickness of the intermediate layer is equal to at least d ref  J ref /J c , where: 
 J c  is a critical energy value specific to a material of the intermediate layer and representative of an energy necessary for propagation of a crack initiated in the intermediate layer;    J ref  is a reference critical energy value which corresponds to a critical energy value of a polyvinyl butyral (PVB) film and is equal to 35,100 J/m 2  for a temperature of 20° C. and for a drawing rate of 100 mm/min applied to the PVB film; and    d ref  is a reference thickness which corresponds to that of the PVB film and is equal to 0.38 mm.    
     
     
         2 . The laminated glazing material according to  claim 1 , wherein the intermediate layer satisfies acoustic property criteria defined by a bar of 9 cm length and 3 cm width, made of laminated glass comprising two glass sheets of 4 mm thickness joined by the intermediate layer having a thickness of 2 mm, has a critical frequency which differs at most by 35% from that of a glass bar having a same length, a same width and a thickness of 4 mm.  
     
     
         3 . The laminated glazing material according to  claim 1 , wherein the intermediate layer has a loss factor greater than 0.6 and a shear modulus of between 1×10 8  and 2×10 7  N/m 2  in a temperature range of between 10 and 60° C. and in a frequency range of between 50 and 10,000 Hz.  
     
     
         4 . A laminated glazing material with properties of acoustic insulation and mechanical strength, said laminated glazing material comprising two glass sheets and a single-ply intermediate layer, wherein the intermediate layer is made of a composite material, said composite material comprising a polymer and reinforcing fibers embedded in the polymer.  
     
     
         5 . The laminated glazing material according to  claim 4 , wherein the intermediate layer satisfies acoustic property criteria defined by a bar of 9 cm length and 3 cm width, made of laminated glass comprising two glass sheets of 4 mm thickness joined by the intermediate layer having a thickness of 2 mm, has a critical frequency which differs at most by 35% from that of a glass bar having a same length, a same width and a thickness of 4 mm.  
     
     
         6 . The laminated glazing material according to  claim 4 , wherein the intermediate layer has a loss factor greater than 0.6 and a shear modulus of between 1×10 8  and 2×10 7  N/m 2  in a temperature range of between 10 and 60° C. and in a frequency range of between 50 and 10,000 Hz.  
     
     
         7 . A polymer film having a thickness for use as an intermediate layer of a laminated glazing material, wherein the thickness is equal to at least d ref J ref /J c , where: 
 J c  is a critical energy value specific to a material of the intermediate layer and representative of an energy necessary for propagation of a crack initiated in the intermediate layer;    J ref  is a reference critical energy value which corresponds to the critical energy value of a polyvinyl butyral (PVB) film and is equal to 35,100 J/m 2  for a temperature of 20° C. and for a drawing rate of 100 mm/min applied to the PVB film; and    d ref  is a reference thickness which corresponds to that of the PVB film and is equal to 0.38 mm.    
     
     
         8 . A polymer film for use as an intermediate layer of a laminated glazing material, wherein the polymer film is a composite comprising a polymer and reinforcing fibers embedded in the polymer.  
     
     
         9 . A process for evaluating a tearing strength of a polymer film of thickness d 1 , for use as an intermediate layer of a laminated glazing material, said process comprising the steps of: 
 determining a critical energy value J c  of the intermediate layer, the critical energy value representing an energy necessary for propagation of a crack initiated in the intermediate layer;    calculating a critical energy value {tilde over (J)} c  relative to the thickness using a relationship {tilde over (J)} c =J c d 1 ;    comparing {tilde over (J)} c  with a reference value {tilde over (J)} ref , representative of a polyvinyl butyral film of 0.38 mm thickness and equal to 13.3 J/m; and    determining when the intermediate layer satisfies a tearing strength criterion when {tilde over (J)} c >{tilde over (J)} ref .