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US 5,846,659 AGranted
UV-protected, multilayer polycarbonate sheets
AssigneeBayer Aktiengesellschaft
InventorsHartmut Lower, Siegfried Anders, Helmut Schmid, Wolfgang Nising
Life of this patent
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Abstract
The present invention relates to UV-protected, multilayer polycarbonate sheets containing a base sheet, at least one outer layer and optionally at least one additional protective layer, and to the production of the polycarbonate sheets according to the invention by coextrusion.
Claims4
UV-protected, multilayer polycarbonate sheets containing:
- 1.1 a base sheet of thermoplastic polycarbonate having two sides which contains 0 to 1 t by weight of UV absorber and which has a viscosity of 500 Pa.multidot.s to 2500 Pa.multidot.s at 280.degree. C. and at a shear rate of 100 s.sup.-1 ;
- 1.2 a second layer of thermoplastic polycarbonate on one or on both sides of the base sheet, which has a content of UV absorber of 2% by weight to 20% by weight and which has a viscosity of 200 Pa.multidot.s to 2300 Pa.multidot.s at 280.degree. C. and at a shear rate of 100 s.sup.-1, characterized in that the viscosity of the second layer 1.2 is at least 50 Pa.multidot.s lower than the viscosity of the base sheet 1.1.
Dependencies are inferred from the claim text.