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 method for molding a polypropylene or a propylene copolymer having a syndiotactic structure which comprises the steps of melting, molding, if desired, quenching and then stretching a propylene homopolymer or a copolymer of propylene and a small amount of ethylene or another .alpha.-olefin which has a substantially syndiotactic structure, or a mixture of the same and a small amount of a polypropylene having a substantially isotactic structure. The molded and stretched article can be heated at a temperature of a molding temperature or more, while a load is applied to the article. Furthermore, the molded and stretched article, if desired, can be treated with a hydrocarbon vapor, while a load is applied to the article. The molded article obtained by the method of the present invention has a novel crystalline structure.

Abstract: A method for increasing the intrinsic viscosity of polypropylene having a substantially syndiotactic structure is disclosed which comprises the step of irradiating the syndiotactic polypropylene with radiation in the absence of oxygen. After the irradiation, the polypropylene is preferably heated. Furthermore, the polypropylene having the substantially syndiotactic structure which remains in a melting state can be irradiated with radiation. The polypropylene having the substantially syndiotactic structure is preferably polypropylene in which any diffraction line is not substantially observed in a spacing of about 7.1 .ANG. by X-ray diffraction.

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 process for producing crosslinked polyolefins having improved physical properties is disclosed. The process comprises irradiating a copolymer of alkenylsilane and olefins, or a mixture of this copolymer and thereof with a polyolefin devoid of alkenylsilane segments.

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: A stretched film of polypropylene which is excellent in transparency, substantially free of an antiblocking agent and at least uniaxially stretched and which is characterized in that it has uniformly distributed projections having a height ranging from 0.05 to 0.50 .mu. and a width ranging from 10 to 100 .mu. at least on the surface thereof as well as a method for preparing the foregoing stretched film of polypropylene which comprises the steps of forming, into a sheet, polypropylene which comprises a nucleating agent in an amount selected so that the crystallization temperature of polypropylene is increased by 1.degree.to 10.degree. C. by the addition thereof and then stretching the sheet at a temperature ranging from 140.degree. to 165.degree. C. are herein disclosed.

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: The present invention relates to the use of a polyolefin resin composition comprising a random copolymer of an alkenylsilane compound and an .alpha.-olefin compound as a material for adhesion or a coating material.

Abstract: The present invention provides polyolefin resin compositions, comprising (i) a polymer containing an alkenylsilane compound and an inorganic filler and (ii) a polyolefin compound which provide molded articles having excellent Izod impact strength, tensile yield strength and stiffness and are also useful for the production of surface-coated molded articles.

Abstract: The invention relates to a block copolymer of propylene and a process for preparing the same comprising (a) polymerizing propylene or .alpha.-olefins mainly comprising propylene in the presence of a catalyst comprising a transition metal catalyst and an organometal compound; (b) copolymerizing .alpha.-olefins mainly comprising propylene and ethylene, wherein in at least one of steps (a) and (b) copolymerization is carried out with an alkenylsilane compound.

Abstract: The present invention relates to .alpha.-olefin block copolymers excellent in adhesive property to polar group-containing polymers and metals as well as in rigidity comprising an alkenylsilane and an .alpha.-olefin and processes for preparing the same, materials for adhesion and for easy coating comprising the same.

Abstract: A block copolymer of propylene can be obtained with its quality controlled uniform by conducting at first continuous polymerization of propylene in a polymerization system, receiving a polymer slurry, which has been discharged continuously from the polymerization system, in a batchwise polymerization tank, feeding ethylene to the tank to conduct batchwise polymerization of ethylene and propylene. Upon discharge of a copolymer slurry formed by the preceding batchwise polymerization, at least a predetermined amount of unreacted ethylene is left over in the tank. Into the tank with the unreacted ethylene still left over therein, there are simultaneously charged the polymer slurry from the polymerization system and a deactivator. During this charging, ethylene is not supplied.

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.

Abstract: In a copolymerization process of propylene, a mixture of unreacted propylene and ethylene is recovered. It is then fed to a distillation system which includes first and second distillation columns. The distillation system is operated in such a way that the temperature and pressure of the top of the second distillation column remain constant and an ethylene-propylene mixture can be recovered at a constant ethylene/propylene ratio from the top of the second distillation column. By using the thus-recovered ethylene-propylene mixture, the copolymerization reaction can be carried out under excellent control so that the ethylene-propylene copolymer can be obtained with uniform quality and properties.

Abstract: A propylene-ethylene block copolymer is produced by continuous bulk polymerization in which propylene alone is polymerized or propylene and ethylene are copolymerized at the ethylene/propylene reaction ratio of 6/94 using propylene as a liquid medium, and subsequently by batch-wise copolymerization in which propylene and ethylene are copolymerized at the ethylene/propylene reaction ratio from 85/15 to 5/95.

Abstract: Disclosed herein is a method for controlling the polymerization temperature in a polymerization apparatus equipped with a cooling system in which steam, which has occurred in the presence of a volatile liquid medium in a reaction system, is condensed in a reflux condenser and the resulting noncondensable gas and condensate are then returned to the reaction system, thereby removing the polymerization heat. A portion of the noncondensable gas is recirculated to the cooling system. The flow rate of the noncondensable gas to be recirculated and the flow rate of a cooling medium to be introduced into the reflux condenser are controlled in accordance with the temperature of the reaction system.