Abstract: Disclosed are a flexible polypropylene resin suitable as thermoplastic elastomer, a propylene based elastomer composition containing the flexible polypropylene resin, and a process for producing the above flexible polypropylene resin and the propylene based elastomer composition. The above flexible polypropylene resin is composed of specific boiling heptane-soluble polypropylene and specific boiling heptane-insoluble polypropylene. The above propylene based elastomer composition comprises the above flexible polypropylene resin and an ethylene/propylene copolymer or an ethylene/propylene/polyene copolymer. The above process for the production of olefin polymers may be carried out by non-solvent polymerization methods such as a gas phase one-step polymerization method, and a gas phase multi-step polymerization method, using a specific catalyst.

Abstract: Disclosed are a flexible polypropylene resin suitable as thermoplastic elastomer, a propylene based elastomer composition containing the flexible polypropylene resin, and a process for producing the above flexible polypropylene resin and the propylene based elastomer composition. The above flexible polypropylene resin is composed of specific boiling heptane-soluble polypropylene and specific boiling heptane-insoluble polypropylene. The above propylene based elastomer composition comprises the above flexible polypropylene resin and an ethylene/propylene copolymer or an ethylene/propylene/polyene copolymer. The above process for the production of olefin polymers may be carried out by non-solvent polymerization methods such as a gas phase one-step polymerization method, and a gas phase multi-step polymerization method, using a specific catalyst.

Abstract: A solid product as a catalyst component for an olefin polymerization catalyst is obtained by the reaction of metallic magnesium, an alcohol, and a halogen in an amount ranging from 0.019 to 0.06 gram-atom per one mole of metallic magnesium. Alternatively, the halogen component is a halogen-containing compound which contains not less than 0.0001 gram-atom of a halogen atom per one gram-atom of metallic magnesium.

Abstract: Disclosed is a process for producing a polyolefin which comprises contacting an olefin with a catalyst comprising:(A) a solid catalyst component comprising, as essential components, (a) a magnesium compound, (b) halogenated titanium and (c) an electron donor compound;(B) an organoaluminum compound; and(C) an organosilicon compound selected from a group consisting of an organosilicon compound (C-1) having the general formula:(R.sup.1 O)(R.sup.2 O).sub.3-n Si(OR.sup.3).sub.n (I)wherein R.sup.1 is a branched hydrocarbon residue; R.sup.2 and R.sup.3 may be the same as or different from each other, and are linear or branched hydrocarbon residues, respectively; and n is from 2 to 3;an organosilicon compound (C-2) having the general formula: ##STR1## wherein R.sup.4 is a hydrocarbon residue in which a carbon atom adjacent to Si is a tertiary carbon atom; and R.sup.5 is a linear or branched hydrocarbon residue; andan organosilicon compound (C-3) having the general formula:R.sup.6 R.sup.7 Si(OR.sup.8).sub.