Appeal No. 2004-2292
Application No. 09/747,537
the group consisting of ethylene-propylene random
copolymers, ethylene-propylene-butene random terpolymers,
propylene-butene copolymers, and low density polyethylene;
(b) a core layer comprising polypropylene, a polymeric
modifier, and a hydrocarbon resin wherein the core layer has
a first side and a second side and the first side of the core layer
is adjacent to the second side of the first skin layer; and
(c) a second skin layer having a first side and a second side
wherein the first side of the second skin layer is adjacent to the
second side of the core layer,
wherein the core layer comprises up to about 15 percent
weight of the polymeric modifier and up to about 15 percent
by weight of the hydrocarbon resin, wherein said film is
biaxially oriented so as to be shrinkable in both the machine
direction (MD) and the transverse direction (TD), and wherein
said film has greater than 20% overall area reduction shrinkage
at 135oC.
The specification discloses that the core layer comprises “a blend of
a more isotactic polypropylene with modifiers which are polyolefin
materials which are less crystallizable due to a higher degree of chain
imperfections or lower isotacticity.” (Specification, p. 3). Suitable modifiers
include polyolefins other than isotactic polypropylene. (Specification, p. 3).
The specification also discloses that hydrocarbon resins are well known
processing aids for polypropylene based films. The hydrocarbon resins are
said to enhance certain physical properties such as stiffness and gloss.
(Specification, p. 1).
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