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1. AU1999058553 - Polymeric films

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters
THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:
1.        An opaque biaxially oriented film comprising a substantially non-voided pigmented core layer of a propylene homopolymer; at least one intermediate layer of a voided propylene homopolymer; and two outer layers of a heat sealable olefin polymer,
wherein the film has density of more than 0.8 g/cm and the voided intermediate layer being from 10 to 30% of the overall film thickness and wherein the pigment of the core layer is T1O 2.
2.        A film according to claim 1 , having at least one intermediate layer.
3.        A film according to claim 1, having an intermediate layer between the core layer and each of the said outer layers.
4.        A film according to any one of the preceding claims, wherein the at least two intermediate layers comprise a voided propylene homopolymer.
5.        A film according to any one of the preceding claims, wherein the core layer contains a substantially non-voiding pigment.
6.        A film according to claim 5, wherein the pigment comprises titanium dioxide.
7.        A film according to any one of the preceding claims, wherein the intermediate layer or layers contains a pigment in addition to a voiding agent.
8.        A film according to any one of the preceding claims, wherein the heat seal layers comprise the same or different heat sealable polyolefins.
9.        A film according to claim 8, wherein the heat sealable polyolefins comprise a copolymer or a terpolymer containing a major amount of units derived from propylene and minor amounts of at least one of ethylene and butene-1 , or a blend of such copolymers and terpolymers.
10.      A film according to any one of the preceding claims, wherein the intermediate layer or layers in total represent from 10 to 30% of the total thickness of the film.
11.      A film according to any one of the preceding claims, wherein the intermediate layer or layers are each up to 5 μιτι thick.
12.      A process for producing a pack with good seal integrity on a vertical form fill-seal packaging machine from a biaxially oriented film comprising a substantially non voided pigmented core layer of a propylene homopolymer, at least one intermediate layer of a voided propylene homopolymer and two outer layers of a heat sealable olefin polymer
wherein the film has a density of more than 0.8 g/cm 3 and the voided intermediate layer being from 10 to 30% of the overall film thickness.