Permeable polymer film

Abstract

Films especially suitable for the packaging of fresh foodstuff, like salad and vegetables, due to their valuable balance of high permeability to oxygen and optimal permeability to water vapour, comprising at least one layer A) and at least one layer B), wherein the layer A) comprises a copolymer of propylene with hexene-1 containing from 3 to 9% by weight of recurring units derived from hexene-1, said copolymer having a melting temperature from 125° C. to 143° C., and the layer B) comprises a polyolefin composition containing (all percentages being by weight): a) 10-40% of one or more propylene homopolymers or copolymers containing over 85% of propylene and having a fraction insoluble in xylene at room temperature greater than 80%; and b) 60-90 of one or more copolymers of ethylene with α-olefin(s), containing ethylene in a quantity from 20 to 80%, and having solubility in xylene at room temperature greater than 70%.

1 . A film comprising at least one layer A) and at least one layer B), wherein the layer A) comprises a copolymer (i) of propylene with hexene-1 containing from 3 to 9% by weight, preferably from 5 to 9% by weight, more preferably from 6 to 9% by weight, in particular from 6.5 to 9% by weight, of recurring units derived from hexene-1, said copolymer having a melting temperature from 125° C. to 143° C., preferably from 128° C. to 143° C., and the layer B) comprises a polyolefin composition (ii) containing (all percentages being by weight):
 a) 10-40%, preferably 20-40%, more preferably 25-38%, of one or more propylene polymers selected from propylene homopolymers, copolymers of propylene with ethylene or a CH2═CHR α-olefin, where R is a C2—C8 alkyl radical, and copolymers of propylene with ethylene and said CH2═CHR α-olefin, said copolymers containing over 85% of propylene and having a fraction insoluble in xylene at room temperature greater than 80%; and 
 b) 60-90%, preferably 60-80%, more preferably 62-75%, of one or more copolymers of ethylene with propylene or a CH2═CHR α-olefin, where R is a C2—C8 alkyl radical, or a combination thereof, and optionally minor quantities of a diene, said copolymers containing ethylene in a quantity from 20 to 80%, preferably from 20 to 40%, more preferably from 20 to 38%, and having solubility in xylene at room temperature greater than 70%, preferably greater than 80%; 
 
       the amounts of (a) and (b) being referred to the total weight of (a) and (b). 
     
     
         2 . The film of  claim 1 , having a A)/B) or A)/B)/A) structure. 
     
     
         3 . The film of  claim 1 , having an overall thickness from 9 to 100 microns. 
     
     
         4 . The film of  claim 1 , prepared by using a blown film process. 
     
     
         5 . The film of  claim 1 , wherein the copolymer (i) has a Melt Flow Rate (MFR, measured according to ISO 1133, 230° C./2.16 kg) from 0.1 to 10 g/10 min., more preferably from 0.1 to 5 g/10 min., in particular from 0.1 to 3 g/10 min. 
     
     
         6 . The film of  claim 1 , wherein the intrinsic viscosity of the fraction soluble in xylene at room temperature of the composition (ii) is from 2 to 4 dl/g. 
     
     
         7 . Food packaging items comprising the film of  claim 1 .