In-reactor stabilization of polyolefins via coated stabilizers

Claim 1

A process for providing in-reactor stabilization of a polyolefin during a polymerization reaction comprising the steps of: forming a particulate adapted for use in polyolefin polymerization reactions, by the steps consisting of heating until liquid a polyolefin wax; fluidizing with a hot gas, additive particles selected from the group consisting of an antioxidant, a processing stabilizer, an acid acceptor, and mixtures thereof; spraying the liquid polyolefin wax on the heated fluidized additive particles; and maintaining the fluidized additive particles at a temperature which is sufficient to prevent the formation of fibers and adequate to form discrete substantially coated additive particles; adding said discrete substantially coated additive containing particles to a polymerization reactor and using a magnesium supported titanium halide/aluminum alkyl catalyst system wherein said system comprises (i) a procatalyst compound obtained by halogenating a magnesium compound of the formula MgR'R" wherein R' is an alkoxide or aryloxide group or halogen, and R" is an alkoxide, alkyl carbonate, aryloxide, or halogen with a halide of tetravalent titanium and electron donor, contacting the halogenated product with a tetravalent titanium halide, washing it to remove unreacted titanium and an electron donor, contacting the halogenated product with a tetravalent titanium halide, washing it in an inert solvent to remove unreacted titanium compounds and recovering the solid product; (ii) a cocatalyst component comprising an organoaluminum compound selected from the group comprising diethyl aluminum chloride, ethyl aluminum dichloride, ethyl aluminum sesquichloride and tri-ethyl aluminum; and (iii) a selectivity control agent selected from the group comprising; diphenyl dimethoxy silane, paraethoxy benzoate, ethyl paratoluate, paramethoxy ethyl benzoate, phenyl triethoxysilane and 2,2,6,6-tetramethyl piperidine.