Aqueous dispersions of olefin copolymers

DETAILED DESCRIPTION OF THE INVENTION The olefin polymer used to prepare the aqueous dispersion of the present invention is from a family of olefin polymers, which are described in U.
S.
Pat.
Nos.
3,645,992, 5,272,236, and 5,278,272 all incorporated herein by reference.
The class of olefin polymers described in U.
S.
Pat.
No.
3,645,992, hereinafter referred to as the Elston olefin polymer, is characterized by being a copolymer of ethylene and at least one other alpha-olefin having four or more carbon atoms, such as 1-butene, 1-hexene, 1-octene, and 1-octadecene.
Interpolymers, such as ethylene-octenebutene or ethylene-octene-propylene are also suitable for the preparation of the aqueous dispersions of the present invention.
The Elston olefin polymer is further characterized by a narrow molecular weight distribution and a homogeneity index of at least 75 as described in the '992 patent.
The olefin polymers described in U.
S.
Pat.
Nos.
5,272,236 and 5,278,272 (collectively referred to as substantially linear olefin polymers) are ethylene-C.
sub.
3 -C.
sub.
20 alpha-olefin copolymers characterized by having 1) high melt elasticity; 2) high processability; 3) a polydispersity index of less than about 3.
5; 4) about 0.
01 to about 3 long chain branches per 1000 carbon atoms along the polymer backbone; and 5) a melt flow ratio that is essentially independent of the polydispersity index.
The olefin polymer of the '236 patent is further characterized as having a critical shear stress rate at onset of gross melt fracture of greater than about 4.
times.
10.
sup.
6 dyne/cm.
sup.
2 ; and the olefin polymer of the '272 patent is further characterized by having a critical shear rate at onset of surface melt fracture of at least 50 percent greater than the critical shear rate at the onset of surface melt fracture of a linear olefin polymer having about the same I.
sub.
2 and M.
sub.
w /M.
sub.
n.
The substantially linear olefin polymers from which the aqueous dispersions are prepared can be homopolymers of C.
sub.
2 -C.
sub