Laminated glass mfr. using polyvinyl butyral film

摘要

A conventional process for mfg. laminated glass comprising a polyvinylbutyral film (2) sandwiched between glass layers uses the roughness of the film at temps. >120 deg C to exclude air trapped at the glass/film interfaces. Additional air channels to enhance air exclusion are created by forming long thin areas (3) across the film (2) width at a much lower temp. than that at which the roughness is produced. The visco-elastic behaviour of the film (2) during or after pressing together of the glass/film layers ensures that the air channels (3) disappear before the assembled laminate is compressed under heat in an autoclave. In a claimed process for mfg. the polyvinylbutyral film the film surface is roughened during or after extrusion and the film passed at 50-120 deg C over a rotating cooled roll (4) with grooves (5). Cooling differences in the film (2) opposite the roll (4) surface and grooves (5) produce thin areas opposite the grooves (5).