Polymeric films having one-sided cling and compositions useful in their preparation
AssigneeThe Dow Chemical Company
InventorLambertus P. P. M. van der Heijden
Life of this patent
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Abstract
A polymeric film prepared from a relatively crystalline polymer such as a copolymer of ethylene and an .alpha.-olefin having at least 3 carbon atoms, e.g., 1-octene (linear low density polyethylene); a relatively amorphous polymer such as low density polyethylene and a tackifying polymer such as a low molecular weight polybutene exhibits a substantially higher cling on one side than the other. A film of a low density polyethylene, linear low density polyethylene and a low molecular weight polybutene also exhibits excellent film strengths and as unexpectedly high resistance to tear, particularly in the cross-direction.
Claims12
A polymeric blend comprising from about 65 to about 80 weight percent of a low density homopolymer of ethylene, from about 20 to about 35 weight percent of a linear low density ethylene copolymer of ethylene and an .alpha.-olefin of 3 or more carbon atoms and from about 2 to 10 weight percent of a polyisobutylene or atactic polypropylene tackifying agent, said weight percents being based on the total weight of the ethylene polymers and tackifying agent, wherein, within the foregoing compositional limitations, the tackifying agent is employed in an amount and the linear low density ethylene copolymer has a sufficiently higher crystallinity than the low density polyethylene such that a film having preferential one-sided cling can be prepared from the blend without corona discharge treatment of the film.
A film having preferential one-sided cling without corona discharge treatment prepared from a polymeric blend comprising from about 65 to about 80 weight percent of a homopolymer of ethylene having a density from 0.91 to about 0.94 g/cc at 20.degree. C. and a degree of crystallinity from about 20 to 30 percent, from about 35 to about 20 weight percent of a copolymer of from about 85 to about 99 mole percent polymerized ethylene with from about 15 to about 1 mole percent polymerized .alpha.-olefin having 3 or more carbon atoms and having a degree of crystallinity from about 40 to about 50 percent and from about 3 to about 8 weight percent of a polymer of isobutylene having a number average molecular weight from about 800 to about 1200, said weight percents being based on the total weight of the first and second polymers and tackifying agent.
Dependencies are inferred from the claim text.