Patent ID: 7892629

Claim:
A method for manufacturing a monolayer interlayer to be inserted in a laminated glazing with acoustic insulation and mechanical strength properties, said glazing comprising two glass sheets and the monolayer interlayer in the form of a polymeric film, the method comprising: selecting a material for the monolayer interlayer for its acoustic insulation properties, such that said monolayer interlayer material satisfies acoustic insulation properties when a critical frequency of a reference bar 9 cm long and 3 cm wide, consisting of a laminated glass comprising two glass sheets 4 mm thick joined by the interlayer with a reference thickness of 2 mm, is compared to a critical frequency of a glass bar having a same length and same width as the reference bar and a 4 mm thickness, and the critical frequency of the reference bar differs by at most 35% from that of the glass bar; measuring a J c critical energy value specific to the selected material of the monolayer interlayer and representative of an energy needed to propagate a crack initiated in the monolayer interlayer; and manufacturing the monolayer interlayer with a thickness such that it satisfies mechanical strength criteria when its thickness is equal to at least d ref J ret /J c , where J ref is a critical reference energy which corresponds to a critical energy of a film of polyvinyl butyral (PVB) and is equal to 35,100 J/m 2 for a temperature of 20° C. and for a pull rate on the PVB film of 100 mm/min applied to the PVB film, and d reg is a reference thickness which corresponds to that of the PVB film and is equal to 0.38 mM.