Patent ID: 11951721
Assignee: BASELL POLIOLEFINE ITALIA S.R.L.
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC B  C | IPC B  C

Claim 0:
1. A biaxially oriented polypropylene multilayer film having at least three layers wherein each layer comprises a nucleated propylene polymer composition comprising:
A) from 77 wt % to 91 wt %, of a propylene homopolymer having a fraction insoluble in xylene at 25° C. higher than 95%, based upon the total weight of the propylene homopolymer;
B) from 9 wt % to 23 wt %, of a copolymer of propylene having from 28.0 wt % to 42.0 wt % of ethylene derived units, based upon the total weight of the propylene copolymer; and
C) from 300 ppm to 5000 ppm with respect to the nucleated propylene polymer composition, of a nucleating agent selected from the group consisting of aromatic or aliphatic carboxylic acids, aromatic metal phosphates, sorbitol derivatives and talc,
wherein the nucleated propylene polymer composition has (i) an intrinsic viscosity of the fraction soluble in xylene at 25° C. between 1.0 dl/g and 1.9 dl/g, (ii) a fraction soluble in xylene at 25° C. between 9.0 wt % and 21.0 wt %, based upon the total weight of the nucleated propylene polymer composition, (iii) a total melt flow rate (Melt Flow Rate according to ISO 1133, condition L, that is, 230° C. and 2.16 kg load) between 1.5 and 5 g/10 min, and (iv) a value of the relation (I):

22.5+0.2*MFR−1.2*Xs+0.2*IV  (I)

higher than 5.9; wherein
MFR is the melt flow rate of the nucleated propylene polymer composition (Melt Flow Rate according to ISO 1133, condition L, that is, 230° C. and 2.16 kg load);
IV is the intrinsic viscosity of the fraction soluble in xylene at 25° C.; and
Xs is the fraction soluble in xylene at 25° C.; and
wherein the amount of A+B is equal to 100 wt %.