High tear strength polymers

A continuous process for making, in the gas phase and at a level of productivity of at least 700 pounds of polymer per pound of total catalyst, heterogeneous ethylene based hydrocarbon polymers having, in film form, high Elmendorf tear strength values which comprises interpolymerizing ethylene with C.sub.a and C.sub.b monomers maintained throughout the process in the molar ratios in said gas phase of C.sub.a /C.sub.2 of about 0.1 to 0.9 and C.sub.b /C.sub.2 of about 0.015 to 0.2

• wherein the C.sub.a monomer is selected from propylene, butene-1 and mixtures thereof and the C.sub.b monomer is one or more C.sub.5 to C.sub.8 alpha monoolefins which contain no branching closer than the fourth carbon atom,
• in a reaction zone having a pressure of about 50 to 1000 psi and a temperature of about 65.degree. to 105.degree. C., with an activated catalyst formed from an activator compound and a precursor compound,
• said activator compound having the structure
• Al(R").sub.c X'.sub.d H.sub.e
• wherein X' is Cl or OR'", R" and R'" are the same or different and are C.sub.1 to C.sub.14 saturated hydrocarbon radicals, d is 0 to 1.5, e is 1 or 0 and c+d+e=3, said precursor compound having the formula
• Mg.sub.m Ti.sub.l (OR).sub.n X.sub.p (ED).sub.q
• wherein
• ED is an electron donor compound which is an organic compound which is liquid at 25.degree. C. at atmospheric pressure, and in which the titanium compound and magnesium compound used to form said precursor compound are partially or completely soluble,
• m is .gtoreq.0.5 to .ltoreq.56
• n is 0, 1 or 2
• p is .gtoreq.2 to .ltoreq.116
• q is .gtoreq.2 to .ltoreq.85
• R is a C.sub.1 to C.sub.14 aliphatic or aromatic hydrocarbon radical or COR' wherein R' is a C.sub.1 to C.sub.14 aliphatic or aromatic hydrocarbon radical,
• X is selected from the group consisting of Cl, Br, I and mixtures thereof, and
• said precursor compound being impregnated in porous carrier material so as to provide a weight ratio of about 0.033 to 0.33 parts of precursor compound to one part of said carrier material, and said precursor compound being either
• completely activated in one step outside of said reaction zone in the absence of solvent, or
• is first partially activated outside of said reaction zone in the presence or absence of solvent and then completely activated inside of said reaction zone.