Method for the production of a thermoplastic film, film produced according to the method and composite safety glass produced by using the film

摘要

A plastic sheet, which initially is biaxially stretched above its glass transition temperature and heat-set, is stretched a second time monoaxially or biaxially at temperatures below its glass transition temperature, the stretching ratio in the two directions being in the range from about 0.5 to 10%. The secondary stretching is carried out at temperatures between about 30 DEG C. and 60 DEG C. This sheet which has been stretched twice is integrated into a laminated safety glass comprising a laminate, in which the plastic sheet carrying a function layer is disposed between two polyvinylbutyral sheets which, in turn, are enclosed between glass panes.