Provided is a novel olefin polymer which is excellent in lightness and moldability, has high rigidity and yields molded products excellent in flexural elasticity. The olefin polymer includes a propylene initial polymerization product formed in the presence of an olefin polymerization catalyst which is a contact reaction product of an olefin polymerization solid catalyst component containing a titanium atom, a magnesium atom, a halogen atom and an internal electron donating compound, at least one organoaluminum compound selected from the compounds of the general formula (I), and a first external electron donating compound; and a polypropylene part formed of a propylene polymerization product formed in the presence of the olefin polymerization catalyst and a second external electron donating compound higher in adsorption to the surface of the olefin polymerization solid catalyst component than the first external electron donating compound.

Provided is a novel olefin polymer which is excellent in lightness and moldability, has high rigidity and yields molded products excellent in flexural elasticity. The olefin polymer includes a propylene initial polymerization product formed in the presence of an olefin polymerization catalyst which is a contact reaction product of an olefin polymerization solid catalyst component containing a titanium atom, a magnesium atom, a halogen atom and an internal electron donating compound, at least one organoaluminum compound selected from the compounds of the general formula (I), and a first external electron donating compound; and a polypropylene part formed of a propylene polymerization product formed in the presence of the olefin polymerization catalyst and a second external electron donating compound higher in adsorption to the surface of the olefin polymerization solid catalyst component than the first external electron donating compound.

The invention relates to isoprene and butadiene and/or pentadiene stereoblock copolymers in which the different stereoregular blocks, joined to each other by means of a single junction point, have different structures and thermal properties. The invention also relates to a process for the preparation of the aforesaid copolymers which comprises the formation of stereoblocks in successive steps but in the presence of a single catalytic system obtained from cobalt dichloride, a phosphine and an organic compound of aluminum.

A 4-methyl-1-pentene polymer particle (X) which satisfies the following requirements (X-a), (X-b) and (X-c): (X-a) being composed of a 4-methyl-1-pentene polymer which has a content of a constitutional unit derived from 4-methyl-1-pentene being 30.0 to 99.7% by mol, and a content of a constitutional unit derived from at least one olefin selected from ethylene and an -olefin having 3 to 20 carbon atoms (except for 4-methyl-1-pentene) being 0.3 to 70.0% by mol; (X-b) having, when measured in a cross fractionation chromatograph apparatus (CFC) using an infrared spectrophotometer as a detector part, at least one peak A of an amount of a component eluted present in the range of 100 to 140 C., and at least one peak B of an amount of a component eluted present at lower than 100 C.; and (X-c) having a meso diad fraction (m) measured by .sup.13C-NMR falling within the range of 95.0 to 100%.

A 4-methyl-1-pentene polymer particle (X) which satisfies the following requirements (X-a), (X-b) and (X-c): (X-a) being composed of a 4-methyl-1-pentene polymer which has a content of a constitutional unit derived from 4-methyl-1-pentene being 30.0 to 99.7% by mol, and a content of a constitutional unit derived from at least one olefin selected from ethylene and an -olefin having 3 to 20 carbon atoms (except for 4-methyl-1-pentene) being 0.3 to 70.0% by mol; (X-b) having, when measured in a cross fractionation chromatograph apparatus (CFC) using an infrared spectrophotometer as a detector part, at least one peak A of an amount of a component eluted present in the range of 100 to 140 C., and at least one peak B of an amount of a component eluted present at lower than 100 C.; and (X-c) having a meso diad fraction (m) measured by .sup.13C-NMR falling within the range of 95.0 to 100%.

A block copolymer composition is disclosed herein. In some embodiments, the block copolymer composition includes a diblock copolymer and a triblock copolymer which each include a polyolefin-based block and a polystyrene-based block. A content of the diblock copolymer is less than or equal to 19% by weight, based on the total weight of the block copolymer composition, the polyolefin-based block includes a repeating unit represented by Formula 1, and the polystyrene-based block includes one or more selected from the group consisting of Formulas 2 and 3.

A method for producing a block copolymer composition including a diblock copolymer and a triblock copolymer each containing a polyolefin-based block and a polystyrene-based block is disclosed herein. In some embodiments, the method includes reacting an organic zinc compound with one or more kinds of olefin-based monomers in the presence of a transition metal catalyst to form an intermediate having an olefin-based polymer block, reacting the intermediate styrene-based monomer in the presence of an alkyllithium compound to form a product having a styrene-based polymer block, and reacting the product with water, oxygen, or an organic acid to form a block copolymer wherein the number of moles of the alkyllithium compound used to form the product is larger than the number of moles of the organic zinc compound used to form the intermediate.

A block copolymer composition is disclosed herein. In some embodiments, a block copolymer composition includes a diblock copolymer and a triblock copolymer, each including a polyolefin-based block and a polystyrene-based block, wherein the polyolefin-based blocks are present between 45 wt % to 90 wt %, wherein the polystyrene-based blocks are present between 10 wt % to 55 wt %, wherein the difference (T) between a thermal decomposition initiation temperature and a thermal decomposition termination temperature (T) measured by Thermo-Gravimetric Analysis (TGA) is 55 C. or greater, and the diblock copolymer and the triblock copolymer do not have a residual unsaturated bond.

The purpose of the present invention is to provide a propylene-based block copolymer, the deposition thereof on the inner wall of the polymerization vessel having been sufficiently inhibited. The propylene-based block copolymer of the present invention has a flowability evaluation value of 40% or less, the value being calculated with the following equation wherein X (sec) is the number of seconds over which 100 g of the copolymer having ordinary temperature falls from a stainless-steel funnel having an inner diameter of 11.9 mm and Y (sec) is the number of seconds over which 100 g of the copolymer which has been held at 80 C. for 24 hours under a load of 10 kg falls from the funnel having an inner diameter of 11.9 mm.

Flowability evaluation value (%)={(Y/X)1}100.

An ethylene-propylene block copolymer resin is provided that is suitable as an insulation layer of an electric power cable. The ethylene-propylene block copolymer is obtained by polymerization of a propylene homopolymer or an ethylene-propylene random copolymer with an ethylene-propylene rubber copolymer in stages in reactors in the presence of a Ziegler-Natta catalyst obtained using two internal electron donors, wherein one of the two internal electron donors is a compound comprising an ester group and an alkoxy group, the ethylene-propylene block copolymer has a melting temperature of 150 to 160 C., the content of the solvent extract thereof when extracted at room temperature with xylene is 30 to 50% by weight, and the intrinsic viscosity of the solvent extract is 1.5 to 3.0 dl/g.