VERFAHREN ZUR HERSTELLUNG VON POLYOLEFINFOLIEN ODER -PLATTEN MIT HOHER FESTIGKEIT.

摘要

High-strength polyolefin film or sheet (I) is mfd. from a mixt. or alloy of at least 2 different polyolefins (II) with m.pt. differing by 5-80 deg.C or of which at least one has MFI value 1.2-20 times higher than that of the other, at a processing temp. 3-80 (pref. 5-70) deg.C above the m.pt. of the lower-m pt. or lower-viscosity polymer up to a max. of 50 (pref. 25 deg.C above that of the higher-melting polymer; the shear rate in the roll gap or slit is 100-10,000 s-1 for film and 10-5000 s-1 for above 0.8-mm sheet. Specifically, (II) are poly(1-4C olefins) with a 10-70 deg.C difference in m.pt. or a 1.5-15 fold different in MFI, processed at 10-50 (10-60 for sheet) deg.C above the lower m.pt. and up to 40 (pref. 20) deg.C above the higher m.pt. with corresp. shear rates of 300-9000 s-1 or 30-4800 s-1 above 1mm), to produce flat film or tube, (I) is mono- or bi-axially stretched at a temp. between the two m.pts. pref. up to 2 deg.C below the higher m.pt., pref. such that the film does not cool to the lower m.pt.