Hoechst Aktiengesellschaft

Horst Eberhardt

Herbert Peiffer

Gerhard Grolig

Werner Roth

Peter Lang

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.degree. C. and 60.degree. 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.

Thermoplastic sheet produced by multiple stretching steps at different

Disclosed is a screw extruder comprising a feed bush having a screw extruder coaxially mounted therein, and which, around its circumference, is provided with several longitudinally extending grooves distributed evenly in the circumferential direction. Adapters are disposed in the grooves which can be adjusted radially in the grooves relative to the extruder screw with the aid of adjustment mechanisms. Each adapter is connected to several bolts connected over the length of the adapter. The bolts pass through holes in the feed bush and are surrounded by helical springs, each of which is supported on the one side against a collar of the bolt and on the other side against a face of the hole. The bolts are of one-piece or two-piece design and may include at the outer bolt ends, rollers which are pressed against cam rings or a cam segment, which surround the extruder barrel in annular or semi-annular shape. The adjustment mechanisms adjust the cam rings or the cam segment and thus, through the bolt, the adapters in the grooves. The adapters may be adjusted in the grooves parallel or inclined to the inner circumferential surface of the feed bush. Also disclosed is a method for controlling extrusion in a screw extruder.

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Walluf, Germany

Horst Eberhardt