Abstract: A syndiotactic polypropylene copolymer is disclosed which comprises 70 to 99.9 mole % of propylene and 0.1 to 30 mole % of an olefin other than propylene; in the 13C-NMR spectrum of the syndiotactic polypropylene copolymer, a ratio of the intensity of a peak at about 20.2 ppm to the sum of the intensities of the total peaks attributable to methyl groups in propylene units at about 19-22 ppm being 0.3 or more. Also disclosed are extrusion-molded high-transparency articles, especially films and sheets and blown films, obtained by the extrusion of a polypropylene substantially having a syndiotactic structure.

Abstract: An insulating composition comprising a syndiotactic polypropylene (s-PP) having a syndiotactic pentad ratio of not less than 0.7 and an MFR of 0.05-2.0 g/10 min. The composition of the present invention comprising a specific s-PP can provide an article having superior electric properties and mechanical properties. In particular, the article can retain superior electric properties and mechanical properties even after rapid cooling or gradual cooling for re-processing of said article. Accordingly, the composition of the present invention can be suitable used for insulating layer, coating layer of various power cables inclusive of high voltage wires and low voltage wires, coating layer of optical fibers and insulator of wire-connecting structures.

Abstract: A fiber excellent in strength and having an average size of 10,000-0.1 denier can be obtained by extruding a new material composed mainly of a polypropylene having a syndiotactic pentad fraction of 0.7 or more and optionally stretching the resulting extruded material. By using as the raw material a composition consisting of two kinds of polypropylenes each having an intrinsic viscosity .eta..sub.1 or .eta..sub.2, the log(.eta..sub.2 /.eta..sub.1) being more than 0.05 or less than -0.05, and a syndiotactic pentad traction of 0.7 or more at a weight ratio of 95:5-5:95 or a composition consisting of at least 50 parts by weight of a syndiotactic polypropylene having the intrinsic viscosity .eta..sub.1 and a syndiotactic pentad fraction of 0.7 or above and at most 50 parts by weight of an isotactic polypropylene having the intrinsic viscosity .eta..sub.2, the extrudability is improved and the fiber stretching conditions are broadened.

Abstract: A radiation-resistant polypropylene resin composition is disclosed which comprises a polypropylene having a substantially syndiotactic structure, and if desired, a phosphorus-containing anti-oxidant, an amine-containing anti-oxidant and/or a nucleating agent. Molded articles obtained from this resin composition can be utilized as containers for foods and medicines, and their physical properties scarcely deteriorate during sterilization by radiation.

Abstract: A radiation-resistant polypropylene resin composition is disclosed which comprises a polypropylene having a substantially syndiotactic structure, and if desired, a phosphorus-containing anti-oxidant, an amine-containing anti-oxidant and/or a nucleating agent. Molded articles obtained from this resin composition can be utilized as containers for foods and medicines, and their physical properties scarcely deteriorate during sterilization by radiation.

Abstract: A fiber excellent in strength and having an average size of 10,000-0.1 denier can be obtained by extruding a raw material composed mainly of a polypropylene having a syndiotactic pentad fraction of 0.7 or more and optionally stretching the resulting extruded material.By using as the raw material a composition consisting of two kinds of polypropylenes each having an intrinsic viscosity .eta..sub.1 or .eta..sub.2, the log(.eta..sub.2 /.eta..sub.1) being more than 0.05 or less than -0.05, and a syndiotactic pentad fraction of 0.7 or more at a weight ratio of 95:5-5:95 or a composition consisting of at least 50 parts by weight of a syndiotactic polypropylene having the intrinsic viscosity .eta..sub.1 and a syndiotactic pentad fraction of 0.7 or above and at most 50 parts by weight of an isotactic polypropylene having the intrinsic viscosity .eta..sub.2, the extrudability is improved and the fiber stretching conditions are broadened.

Abstract: Disclosed herein is a process for preparing a syndiotactic polypropylene comprising washing with a hydrocarbon solvent a polymer obtained by polymerizing propylene in the presence of a catalyst comprising a transition metal compound having an asymmetric ligand. The slurry of the polymer obtained by the polymerization is treated with a .beta.-dicarboxy compound and an alcohol or with an alcohol containing hydrochloric acid gasunder non-aqueous conditions prior to the washing with a hydrocarbon solvent so that the residue of the catalyst used in the polymerization reaction may be rendered soluble in the hydrocarbon solvent, the properties of the resulting syndiotactic polypropylene are improved greatly.

Abstract: A radiation-resistant polypropylene resin composition is disclosed which comprises a polypropylene having a substantially syndiotactic structure, and if desired, a phosphorus-containing anti-oxidant, an amine-containing anti-oxidant and/or a nucleating agent. Molded articles obtained from this resin composition can be utilized as containers for foods and medicines, and their physical properties scarcely deteriorate during sterilization by radiation.

Abstract: Disclosed herein is a polypropylene resin composition of a high syndiotacticity comprising a substantial homopolymer of propylene, in which the ratio of the intensity of the peak attributable to the syndiotactic pentad bonds to the sum of the intensities of all the peaks attributable to the methyl groups in the spectrum of the methyl groups measured by .sup.13 C-NMR is 0.7 or more, and a copolymer of ethylene and propylene, and a preparation process thereof.

Abstract: A syndiotactic polypropylene resin composition comprising a polypropylene having a substantially syndiotactic structure and a nucleating agent. The syndiotactic polypropylene may be a homopolymer of the propylene, a copolymer of the propylene and a smaller amount of another olefin or a mixture of the above-mentioned (co)polymer and an isotactic polypropylene. The resin composition preferably has a higher crystallization temperature than a polypropylene containing no nucleating agent by 5.degree. C. or more, as measurement is made by a differential scanning thermal analysis.

Abstract: Copolymers of butene-1 and propylene, having specific physical properties and substantially a syndiotactic structure; and easily heat-sealable polypropylene resin compositions comprising 5-50 parts by weight of one of the copolymers and 95-50 parts by weight of a stereoregular crystalline propylene-ethylene copolymer or propylene ethylene-C.sub.4-12 -.alpha.-olefin copolymer having specific compositions and melt flow index.

Abstract: According to the present invention, molded articles can be provided in which a melting point attributed to a syndiotactic polypropylene and measured at a temperature rise rate of 10.degree. C./minute by differential scanning thermal analysis is indicated by a substantially single peak, the aforesaid molded articles being obtained by heating, melting and molding a substantially syndiotactic homopolymer of propylene, a substantially syndiotactic copolymer of propylene and a small amount of another olefin, or a mixture of these polymers and a small amount of a substantially isotactic polypropylene, and then subjecting the molded products to a heat treatment. Furthermore, a method for preparing the above-mentioned molded articles is also provided. The molded articles have high stiffness and impact resistance.

Abstract: Disclosed herein is a polypropylene resin composition of a high syndiotacticity comprising a substantial homopolymer of propylene, in which the ratio of the intensity of the peak attributable to the syndiotactic pentad bonds to the sum of the intensities of all the peaks attributable to the methyl groups in the spectrum of the methyl groups measured by .sup.13 C-NMR is 0.7 or more, and a copolymer of ethylene and propylene, and a preparation process thereof.

Abstract: Copolymers of butene-1 and propylene, having specific physical properties and substantially a syndiotactic structure; and easily heat-sealable polypropylene resin compositions comprising 5-50 parts by weight of one of the copolymers and 95-50 parts by weight of a stereoregular crystalline propylene-ethylene copolymer or propylene-ethylene-C.sub.4-12 -.alpha.-olefin copolymer having specific compositions and melt flow index.

Abstract: A poly-.alpha.-olefin of novel structure which is an addition polymer of an .alpha.-olefin having 4 carbon atoms or more, wherein (a) by the analysis of the peaks attributable to the side chain methylene groups directly bonded to the main chain in the .sup.13 C-NMR spectrum produced by the measurement in 1,2,4-trichloro-benzene, (i) a novel main peak not attributable to the isotactic structure thereof is positioned on the side of higher magnetic field than is the peak attributable to the isotactic structure, and (ii) the intensity of said main peak is 0.3 or more relative to the sum of the intensities of the total peaks attributable to the side chain methylene groups directly bonded to the main chain, and (b) the molecular weight measured by gel permeation chromatography and calculated as polypropylene is not less than 1,000.

Abstract: An improved method for preparing block copolymers of propylene which comprises providing a polymerizer composed of at least two reaction vessels connected to one another, substantially homopolymerizing propylene in a first step and then copolymerizing ethylene and propylene in a second step in the presence of a stereoregular catalyst, characterized by carrying out the homopolymerization of propylene in the polymerizer composed of at least two reaction vessels connected to one another in series, then introducing the resulting polymer slurry into a countercurrent washing column and countercurrently washing the slurry with propylene, introducing the washed slurry withdrawn from the lower part of the washing column into a reaction vessel in the second step connected to the washing column and performing the polymerization of ethylene and propylene, of which ratio ranges from 15/85 to 95/5. According to this method, a block copolymer of propylene exhibiting excellent physical properties can be obtained efficiently.

Abstract: A copolymer of propylene and butene-1, the constituent monomer units of which comprise 20-63 wt. % of propylene and 37-80 wt. % of butene-1, and which exhibits 0.5 or more in the ratio of the sum of the intensities of absorptions observed at about 20.0-21.0 ppm to the sum of the intensities of total absorptions attributable to the methyl groups in the propylene units observed at about 19.0-22.0 ppm in the .sup.13 C-NMR spectrum measured in a 1,2,4-trichlorobenzene solution and 0.05 or more in the intrinsic viscosity measured at 135.degree. C. in a tetralin solution.

Abstract: A polymer of 4-methylpentene-1 having a substantially syndiotactic structure, which polymer contains 0 to 30 mol % of the .alpha.-olefin unit other than the 4-methylpentene-1 unit and has excellent physical properties.

Abstract: Disclosed herein is a method for controlling the molecular weight of a propylene homo- or co-polymer at a constant level upon subjecting propylene alone or a mixture of propylene and another .alpha.-olefin copolymerizable with propylene as a monomer or monomer mixture to bulk polymerization in the presence of hydrogen as a molecular weight modifier in a reaction tank equipped with a reflux condenser.

Abstract: A block copolymer of propylene is produced by using propylene itself as a liquid medium, conducting continuous polymerization (former-stage polymerization) of propylene alone or propylene and a small amount of ethylene at first and then conducting batchwise copolymerization (latter-stage polymerization) of ethylene and propylene. The amount of an activity improver to be added to a polymerization tank for the latter-stage polymerization and/or the polymerization time of the latter-stage polymerization are controlled in accordance with the amount of a slurry transferred from a polymerization tank for the former-stage polymerization to the polymerization tank for the latter-stage polymerization so as to maintain the ratio of the amount of the polymer polymerized by the former-stage polymerization to the amount of the polymer polymerized by the latter-stage polymerization constant in the block copolymer.