Abstract: A lanthanide based olefin polymerization catalyst and its use in polymerization are disclosed. The lanthanide based catalyst is prepared by contacting a lanthanide halide with an ether, then contacting the resulting lanthanide composition with an alkali or alkaline earth metal alkyl compound, and depositing the resulting lanthanide product on a particulate support.

Abstract: High cis-1,4-polybutadiene can be synthesized by polymerizing 1,3-butadiene monomer with a three component nickel catalyst system containing (a) an organonickel compound, (b) an organoaluminum compound, and (c) a fluorine containing compound. However, the molecular weight of the high cis-1,4-polybutadiene prepared is typically too high to be utilized as a non-oil extended rubber. This invention is based upon the discovery that halogenated phenols act to reduce the molecular weight and to increase the molecular weight distribution of high cis-1,4-polybutadiene prepared with such nickel based catalyst systems. The use of halogenated phenols as modifiers in such polymerizations does not change the microstructure of the high cis-1,4-polybutadiene produced.

Abstract: A process for the production of thermoset polymers comprising contacting at least one monomer of the formulae: ##STR1## with a metathesis catalyst system which comprises a tungsten catalyst and a tin or silicon hydride cocatalyst.

Abstract: Trans-1,4-polybutadiene is a thermoplastic resin by virtue of its high level of crystallinity. Because trans-1,4-polybutadiene contains many double bonds in its backbone, it can be blended and cocured with rubbers. Even through trans-1,4-polybutadiene is a thermoplastic resin, it becomes elastomeric when cured alone or when cocured with one or more rubbers. By utilizing the catalyst system and techniques of this invention, trans-1,4-polybutadiene can be synthesized continuously to a high level of conversion with only minimal amounts of gel formation.

Abstract: This invention relates to a two component catalyst system for polymerization of metathesis polymerizable cycloolefins, comprising(a) a tungsten compound of the formula WOCl.sub.4-x (OAr).sub.x wherein Ar represents a hindered phenyl ring having bulky alkyl, alkoxyl halogen or aryl groups in the 2,6 position, i.e., diisopropyl or phenyl group and x=1, 2 or 3; and(b) an activator compound that is triphenyl tin hydride or trialkyl tin hydride, preferably a tributyltin hydride.Among the preferred molecules or groups that are substituted on the phenyl ring of the tungsten compound include chlorine, bromine, phenyl, methoxy and isopropyl. Ar may also represent a multisubstituted phenyl group such as 2,4-dichloro-6-methyl phenyl.

Abstract: Disclosed is a method of moderating the catalyst activation characteristics of an alkyl aluminum compound by the use of hydrocarbon substituted acetylene. Preferred compounds are phenylacetylene, hexyne-1-and hexyne-2.

Abstract: A process for producing a polymer or copolymer of an olefin which comprises polymerizing or copolymerizing at least one olefin with or without a diolefin in the presence of a catalyst composed of (A) a magnesium-containing solid titanium catalyst component containing magnesium, titanium, a halogen and an electron donor as essential ingredients and (B) an organoaluminum compound catalyst component; characterized in that(1) said catalyst further comprises (C) an organic silicon compound catalyst component having an Si--O--C or Si--N--C bond, and(2) said electron donor in the catalyst component (A) is a cyclic mono- or poly-ester such as diethyl furane-3,4-dicarboxylate, di-n-butyl 3,4-dihydro-2H-pyrane-5,6-dicarboxylate, di-isobutyl pyrrole-2,3-dicarboxylic, di-n-butyl thiophene-2,3-dicarboxylate, n-octyl pyrrolidine-2,3-dicarboxylate, and so on.

Abstract: A process for producing a molded article by introducing a reactive liquid mixture which comprises a cycloalkene containing dicyclopentadiene, a norbornene-type monomer containing at least one N-substituted 5-membered cyclic imide group and a metathesis polymerization catalyst system and which has moderated metathesis polymerizability into a mold in which the liquid mixture is metathesis polymerized, and a multi-part polymerizable composition for producing the molded article.

Abstract: A process for the manufacture of a linear polyethylene with narrow molecular-weight distribution comprising polymerizing ethylene alone or a mixture of ethylene and an alpha-olefin in which ethylene represents at least about 70% by weight of the total monomers involved, in a gas-phase polymerization medium in the presence of a catalytic component containing at least one transition metal, magnesium, and a halogen, a co-catalyst comprising an alkylaluminum compound, and a monoether, the monoether having the general formula R'OR", wherein R' and R" are the same or different and each is a C.sub.1 to C.sub.8 linear or branched hydrocarbon radical or being a cyclic monoether with the oxygen forming a ring having 4 to 12 carbon atoms.

Abstract: Ethylene homopolymers or copolymers having a very low molecular weight are continuously prepared in a fluidized bed in the presence of high concentrations of hydrogen, while maintaining high catalyst activity, by means of a vanadium-based catalyst.

Abstract: A catalyst comprising (A) a solid catalyst component obained by reacting a homogeneous solution containing (i) at least one member selected from the group consisting of a combination of metallic magnesium and a hydroxyl organic compound, and an oxygen-containing organic compound of magnesium, (ii) an electron donor compound and (iii) an oxygen-containing organic compound of titanium with (iv) at least one aluminum halide compound and further reacting the obtained solid product with (v) an electron donor compound and (vi) a titanium halide compound, (B) at least one member selected from the group consisting of organic metal compounds of metals of the groups Ia, IIa, IIb, IIIb and IVb of the periodic table, and (C) an electron donor compound, is valuable as the catalyst for preparing a stereoregular polyolefin by homopolymerization or copolymerization of an .alpha.-olefin having at least 3 carbon atoms.

Abstract: Olefins are polymerized under solution polymerization conditions in the presence of the solid catalytic product resulting from removing the liquid components from the product resulting from admixing in an inert diluent and in an atmosphere which excludes moisture and oxygen (A) at least one hydrocarbon soluble organomagnesium compound; (B) at least one organic hydroxyl-containing compound; (C) at least one reducing halide source; (D) at least one transition metal (Tm) alkoxide.

Abstract: Alternating copolymers having a high alternating degree and high isotacticity, which can be produced by copolymerizing ethylene and an aromatic vinyl monomer in the presence, as a catalyst, of a transition metal compound, aluminoxane and a specific organic compound having at least two hydroxyl groups.

Abstract: A catalyst system comprising(A) a halogen compound of trivalent titanium,(B) an organo-aluminum compound of the formula,R.sub.3-(m+n) AlY.sub.m X.sub.nwhereinY is a group having at least one of oxygen, nitrogen, sulfur and phosphorus atoms linked to the aluminum atom, R is a hydrogen atom, an alkyl having 1 to 18 carbon atoms, an alkenyl having 2 to 18 carbon atoms, a cycloalkyl having 3 to 18 carbon atoms, an aryl having 6 to 18 carbon atoms, or an aralkyl having 7 to 18 carbon atoms,X is a halogen atom, and m and n are numbers satisfying the equations, 0<m<1, 0.ltoreq.n<2, 0<m+n.ltoreq.2, and(C) an electron-donor, and a method for producing an olefin polymer which comprises polymerizing olefins using said catalyst system. According to this method, highly crystalline olefin polymers having a broad melecular weight distribution can be produced.

Abstract: There is disclosed a highly active catalyst composition for polymerizing alpha-olefins prepared by treating a support with an organomagnesium composition and contracting the thus formed solid support, containing magnesium, in a liquid medium with a transition metal compound, e.g., a tetravalent titanium compound. This catalyst is particularly useful for the production of linear low density polyethylene polymers. Also disclosed are methods of preparing polymers with the catalyst composition and the resulting polymers.

Abstract: A process for preparing molded objects wherein a liquid reaction mass comprised of a metathesis polymerizable cycloolefin, a metathesis polymerization catalyst, a catalyst activator and a reaction rate moderator are charged to a mold wherein polymerization will take place, the improvement wherein said catalyst activator comprises a dialkylzinc compound. Significantly increased gel and cure times are obtained with the dialkylzinc compounds as compared to the use of aluminum alkyl activator compounds. The gel and cure times may be further controlled by the addition of a phenolic compound to the tungsten or molybdenum compound or by the addition of a Lewis base.

Abstract: Pure syndiotactic 1,2-polybutadiene is a thermoplastic resin which has double bonds attached in an alternating fashion to its polymeric backbone. Films, fibers and molded articles can be made utilizing syndiotactic 1,2-polybutadiene. It can also be blended into rubbers and cocured therewith. Syndiotactic 1,2-polybutadiene can be made by solution, emulsion or suspension polymerization. It typically has a melting point which is within the range of about 195.degree. C. to about 215.degree. C. However, it is often desirable for the syndiotactic 1,2-polybutadiene to have a melting point of less than about 195.degree. C. This invention discloses a process for preparing syndiotactic 1,2-polybutadiene having a melting point of less than about 195.degree. C.

Abstract: A cross-linked copolymer containing repeating units derived from a mixture comprising the following monomers: ##STR1## and occasionally other repeating units derived from other metathesis polymerizable cyclic compounds such as dicyclopentadiene, a process for producing the copolymer, a process for producing a molded article from the copolymer and a polymerizable composition therefor.

Abstract: The processability of a polybutadiene with a high content of 1,4-cis-structure is improved by means of the addition of PCl.sub.3 before the polymerization reaction is quenched and when Mooney viscosity of polybutadiene has reached a prefixed value, preferably lower than, or equal to 30; the polymerization of butadiene is carried out in a solution in an aliphatic or cycloaliphatic solvent, in the presence of a catalytic system based on rare earths, preferably a neodymium-based catalytic system.

Abstract: An ethylene polymerization catalyst comprising a supported precursor of vanadium trihalide/electron donor complex and alkylaluminum or boron halides, when combined with alkylaluminum cocatalyst and alkyl halide promoter, provides enhanced polymerization and productivity plus superior polyethylene.

Abstract: There is provided a process for polymerization of an .alpha.-olefin which comprises polymerizing an .alpha.-olefin in the presence of a catalyst which is a combination of a solid component (A), which is obtained by subjecting a composition (A.sub.O) comprising as the essential ingredients titanium, magnesium and a halogen to preliminary polymerizatoin of the .alpha.-olefin conducted in the presence of said composition in a slurry and an organoaluminum compound, and an organoaluminum compound (B), said preliminary polymerization being conducted in two steps: the first step wherein the concentration of said composition (A.sub.O) in the slurry is adjusted to 10-100 g/lit.-solvent and polymerization of the .alpha.-olefin is conducted at 30.degree. C. or lower so that the amount of a polymer produced is 0.001 to 1 g per gram of said composition and the second step wherein polymerization of the .alpha.-olefin is conducted at 60.degree. C.

Abstract: A process for the regulation of the molecular weight of a high cis 1,4-polybutadiene prepared by polymerizing 1,3-butadiene in a solution of an aliphatic and/or cycloaliphatic solvent system employing as a catalyst system a mixture of (1) an organonickel compound, (2) an organoaluminim compound and (3) a fluorine containing compound selected from the group consisting of hydrogen fluoride and hydrogen fluoride complexes prepared by complexing hydrogen fluoride with ketones, esters, ethers, alcohols, phenols and water, said polymerization being conducted in the presence of small amounts of alpha olefins such as ethylene and propylene.

Abstract: An olefin, particularly alpha-olefin, supported catalyst composition, containing a transition metal or a compound thereof and an activator, has an average pore diameter of about 20 to about 300 Angstroms, at a substantially constant catalyst particle size for a given range of average pore diameters. The catalyst produces polymers having gradually decreasing molecular weight distribution with decreasing pore size of the catalyst at a constant particle size.

Abstract: A highly crystalline polypropylene is provided having:(A) (i) a melt flow rate (MFR) in the range of 0.1-200 g/10 minutes 230.degree. C. and (ii) an absorbance ratio determined by infrared absorption spectroscopy, IR-.rho., of wave-number 997 cm.sup.-1, A.sub.997, to wave-number 973 cm.sup.-1, A.sub.973, which satisfies the equation:IR-.tau..gtoreq.0.0203 log MFR+0.950; and(B) (i) an IR-.tau. value of at least 0.97 of a component deposited initially in an amount of 2 to 3% by weight from a dilute, slowly cooled and stirred xylene solution of the polypropylene and (ii) a ratio of the weight average molecular weight of the deposited component (M.sub.w1) to that of the polypropylene (M.sub.w0), M.sub.w1 /M.sub.w0, of at least 3.

Abstract: A method of producing a polyolefin. An olefin is polymerized in the presence of a catalyst containing (A) a catalyst component containing magnesium, titanium, halogen and an electron donor, (B) an organoaluminum compound and (C) an external electron donor which is an ether compound (C.sup.1) of the formula [1a]: ##STR1## or formula [1b]: ##STR2## wherein R.sup.1, R.sup.2, R.sup.4 and R.sup.7 are saturated or unsaturated aliphatic hydrocarbyl group having 1 to 7 carbon atoms; R.sup.3 and R.sup.6 are a hydrogen atom or a saturated or unsaturated aliphatic hydrocarbyl group having 1 to 7 carbons and R.sup.5 is a divalent aliphatic hydrocarbyl group having 1 to 7 carbon atoms. The catalyst used in the polymerization may also contain a carboxylate, organosilicon compound and/or an azo compound.

Abstract: The present invention relates to a butene-1 copolymer composition which has excellent heat sealing properties, mechanical characteristics, moldability, and transparency without lowering its surface characteristics, and is characterized by containing 75 to 99.5% by weight of a butene-1 copolymer comprising butene-1 unit and .alpha.-olefine having a carbon number of 2 to 3, and 25 to 0.5% by weight of a propylene polymer, the said butene-1 copolymer has an .alpha.-olefine unit content of 1 to 35 mol %, intrinsic viscosity of 0.9 to 7.2 dl/g, weight-average molecular weight/number-average molecular weight of 4 to 15, and the content of the boiling diethyl ether soluble component is 3 to 15% by weight of the copolymer.

Abstract: Ultra-high-molecular-weight polyolefin fine powder characterized in that said fine powder has an intrinsic viscosity measured in decalin at 135.degree. C. of at least 10 dl/g and an average particle diameter in the range of 1-80 .mu.m, at least 20 weight % of the powder passing through 350 Tyler mesh screen.

Abstract: A catalyst component for the polymerization of olefins which is prepared by contacting a reaction product of dihydrocarbyl magnesium and a halogen-containing alcohol held in contact with a titanium compound.

Abstract: Process for adjusting the cis-trans-double bond configuration in polyalkenamers produced by ring-opening polymerization of cis,cis-1,5-cyclooctadiene or 2-norbornene wherein the polymerization is performed in the presence of isoprene and/or a cyclic olefin with a double-bond pair in the 1,3-position.

Abstract: Methods of preparing storage stable components useful for metathesis bulk polymerization of cycloolefin monomers are provided. These components contain cycloolefins with norbornene-functional groups and cocatalysts activated with a halometal compound. In these methods, the cocatalyst is completely formed before the halometal activator is added to prevent the formation of unwanted hydrogen halides, which catalyze undesired crosslinking reactions which destabilize the cocatalyst component. Bulk polymerization systems are provided wherein these storage stable cocatalyst components are paired with catalyst components that together form the complete metathesis catalyst system. For some embodiments, storage stability is aided by the removal of water.

Abstract: The invention concerns copolymers of propylene and but-1-ene in which the proportion of units derived from but-1-ene is from 10 to 40% by weight and the proportion of isolated ethyl branches which they contain is at least equal to the square of the proportion [P] of units derived from propylene contained in said copolymers. The copolymers of the invention can be used for the production of heat-sealable films.

Abstract: A vanadium-based catalyst is treated with certain oxygen-containing compounds as a means of narrowing and effectively regulating the molecular weight distribution of the polymers produced with the catalyst.

Abstract: A metathesis polymerization catalyst composition comprising a binuclear catalyst, wherein said binuclear catalyst is a mixture of at least two transition metal components, wherein a first transition metal component is a halide complex of tungsten, an oxyhalide complex of tungsten or a mixture thereof and a second transition metal component is a halide complex of a transition metal selected from the group consisting of high valent transition metals belonging to Groups IV or V of the Periodic Table, from about 1 to about 3 moles of phenolic compound per mole of tungsten component, activated by a metathesis catalyst activator and containing a rate moderator.

Abstract: High vinyl polybutadiene rubber is utilized in a variety of applications. For instance, high vinyl polybutadiene is utilized in tire tread rubber compositions because it provides both good traction and rolling resistance. The present invention discloses a technique for synthesizing high vinyl polybutadiene utilizing a molybdenum catalyst system. This molybdenum catalyst system can be utilized in aliphatic solvents with high yields of about 75% being attained. The molybdenum catalyst systems of this invention are comprised of (a) a molybdenum containing compound which is prepared by modifying molybdenum pentachloride, molybdenum trichloride, or molybdenum tetrachloride with an alkyl carboxylic acid or an aryl carboxylic; and (b) an aluminum containing compound which is prepared by modifying a trialkyl aluminum compound with a phenol. The molecular weight of the high vinyl polybutadiene being prepared can be reduced by modifying the trialkyl aluminum compound with an allylphenol, such as 2-allylphenol.

Abstract: A catalyst for polymerizing olefins is the product resulting from mixing in an inert hydrocarbon diluent, a mixture of (A) an inorganic oxide, (B) an organomagnesium material, (C) an organic hydroxyl-containing material, (D) a reducing halide source, and (E) a transistion metal compound.

Abstract: Disclosed is a method of reducing the activation rate of an alkyl aluminum activator in the metathesis polymerization of polycyclic cycloolefins. Activation rate is reduced by use of a bidentate Lewis base as the reaction rate moderator.

Abstract: A process for preparing molded objects wherein a liquid reaction mass comprised of a metathesis polymerizable cycloolefin, a metathesis polymerization catalyst, a catalyst activator and a reaction rate moderator are charged to a mold wherein polymerization will take place, the improvement wherein said catalyst activator comprises a dialkylzinc compound. Significantly increased gel and cure times are obtained with the dialkylzinc compounds as compared to the use of aluminum alkyl activator compounds. The gel and cure times may be further controlled by the addition of a phenolic compound to the tungsten or molybdenum compound or by the addition of a Lewis base.

Abstract: A catalyst composition for polymerizing alpha-olefins is prepared by treating a carrier containing OH groups with a liquid solution containing an excess of an organomagnesium composition with respect to the OH groups and contacting the thus-formed magnesium-containing carrier with a hydrocarbyl alcohol and at least one transition metal compound. Prior to contacting the magnesium-containing carrier with the alcohol, most of the liquid must be removed therefrom, so that it comprises not more than about 6% of the liquid. The amount of the transition metal compound is such that the molar ratio thereof to magnesium in the reaction mixture is about 0.3 to about 0.9. Also disclosed is a process for polymerizing alpha-olefins in the presence of the catalyst of the invention.

Abstract: Olefins are polymerized under slurry conditions in the presence of a cocatalyst and a catalyst prepared by a method wherein a mixture (A) containing the product resulting from mixing in an inert hydrocarbon diluent (1) a hydrocarbon soluble magnesium alkyl compound, (2) an aliphatic alcohol and (3) a titanium compound is reacted with (B) a reducing halide source. Components (A) and (B) are mixed at a constant initial temperature. When the concentration of components (A) and (B) in said hydrocarbon solvent is relatively low and when the ratio of the number of moles of aliphatic alcohol:total number of hydrocarbyl groups attached to the metal atom in component (1) is relatively low, the resultant polymer has a relatively small average particle size and a relatively narrow particle size distribution.

Abstract: Ethylene and alpha-olefins are homopolymerized or copolymerized with another olefin monomer in the presence of a catalyst system comprising an organo metal cocatalyst and a titanium-containing catalyst component, said titanium-containing catalyst component being obtained by reacting together a porous particulate material, an organic magnesium compound, an oxygen-containing compound, an acyl halide, titanium tetrachloride and Cl.sub.2, Br.sub.2 or an interhalogen compound and treating the solids with an aluminum alkyl.

Abstract: Process of polymerization of unsaturated hydrocarbons, with an initial induction period, by means of a catalyst constituted by a halogeno-phenate of tungsten, of which the phenate group carries one or more substituents, in the presence of an organometallic co-catalyst; the halogeno-phenate is chosen from amongst those represented by the formula ##STR1## where X is a halogen, especially Cl or Br, n is a whole number 2, 3 or 4, R.sup.1 is H or a C.sub.1 to C.sub.8 straight- or branched-chain alkoxy group, R.sup.2 is H or a C.sub.3 to C.sub.9 branched-chain alkyl group, R.sup.1 and R.sup.2 never being hydrogen simultaneously.

Abstract: A process for the stereoregular polymerization of alpha olefins which comprises polymerizing an alpha olefin having from 2 to 8 carbon atoms in the presence of a catalyst comprising: (a) a solid supported titanium tetrahalide complex, wherein said complex is prepared by contacting a mechanically pulverized solid support with titanium tetrahalide in the absence of mechanical pulverization, and (b) a cocatalyst comprising a mixture of a dialkyl aluminum halide and a dialkyl magnesium or alkyl lithium compound.

Abstract: A process for polymerizing or copolymerizing a member of the group consisting of an alpha olefin or mixtures thereof, consisting of the steps of:polymerizing an alpha olefin in a polymerization reactor using a polymerization catalyst, a cocatalyst, and an amount of hydrogen adjusted for molecular weight control as measured by melt flow;rapidly changing the melt flow of the polymerized alpha olefin from high to low melt flow by reacting a portion of the unreacted hydrogen in the reactor with a quantity of the alpha olefin present therein by interaction with a hydrogenation catalyst; andremoving the hydrogenation catalyst from the reactor through continuous exchange of the reactor contents.

Abstract: A process for producing a polymer or copolymer of an olefin which comprises polymerizing or copolymerizing at least one olefin with or without a diolefin in the presence of a catalyst composed of (A) a magnesium-containing solid titanium catalyst component containing magnesium, titanium, a halogen and an electron donor as essential ingredients and (B) an organoaluminum compound catalyst component; characterized in that(1) said catalyst further comprises (C) an organic silicon compound catalyst component having an Si--O--C or Si--N--C bond, and(2) said electron donor in the catalyst component (A) is a cyclic mono- or poly-ester such as diethyl cyclohexene-1,2-dicarboxylate, di-n-butyl 1,3-cyclohexadiene-1,2-dicarboxylate, diethyl furane-3,4-dicarboxylate, di-n-butyl 3,4-dihydro-2H-pyrane-5,6-dicarboxylate, diethyl ester of cyclohexene-1,6-dicarboxylic acid, and so on.

Abstract: A supported alpha-olefin polymerization catalyst composition is synthesized by reacting (1) a slurry of a solid catalyst carrier in a non-polar solvent, e.g., hexane, with a dialkyl organomagnesium composition; (2) contacting the slurry of step (1) with a hydroxyl group-containing compound, e.g., an alcohol; (3) contacting the slurry of step (2) with at least one transition metal compound; (4) contacting the slurry of step (3) with a halogenated alkyl aluminum compound, e.g., ethyl aluminum dichloride, and, (5) activating the product of step (5) with trimethylaluminum. The resulting catalyst composition is extremely active in polymerizing C.sub.2 -C.sub.10 alpha-olefins and exhibits very good higher (C.sub.3 -C.sub.10) alpha-olefins incorporation properties.

Abstract: Disclosed is a method of reducing the activation rate of an alkyl aluminum activator in the metathesis polymerization of polycyclic cycloolefins. Activation rate is reduced by use of a bidentate Lewis base as the reaction rate moderator.

Abstract: A process for the preparation of linear low density polyethylene by the copolymerization of ethylene and 1-butene which comprises contacting ethylene with a feedstock comprising 1-butene in the presence of a catalyst comprising:(a) a solid supported titanium tetrahalide complex, wherein said complex is prepared by contacting a mechanically pulverized solid support with titanium tetrahalide in the absence of mechanical pulverization, and(b) a cocatalyst comprising a mixture of dialkyl aluminum halide and a dialkyl magnesium or alkyl lithium compound.

Abstract: Olefins are polymerized in the presence of, as a catalyst therefor, the unseparated catalytic reaction product resulting from heating a mixture of(A) at least one hydrocarbon soluble organomagnesium material;(B) at least one organic hydroxyl-containing material;(C) at least one reducing halide source; and(D) at least one transition metal (Tm) compound.

Abstract: A supported solid catalyst composition for polymerizing alpha-olefins is prepared by treating a carrier with a transition metal compound. The carrier utilized in the synthesis must have such an average pore diameter that the resulting catalyst composition has an average pore diameter of at least about 170 Angstroms. The catalyst composition has higher productivity than similar catalyst compositions of lower average pore diameter, and it produces polymers of lower density and higher melt and high load melt indexes than such similar catalyst compositions of lower average pore diameter. Also disclosed is a process for polymerizing alpha-olefins in the presence of the catalyst of the invention.

Abstract: A packaging transparent propylene copolymer film stretched in at least one direction, which consists of a copolymer of propylene and an .alpha.-olefin having 4 or more carbon atoms or a copolymer of propylene, an .alpha.-olefin having 4 or more carbon atoms and ethylene. The copolymer satisfies the following conditions;(1) the content of the .alpha.-olefin having 4 or more carbon atoms in the copolymer is 8-25 mole %,(2) the content of ethylene in the copolymer is 5 mole % or less,(3) the content of a cold xylene-soluble portion in the copolymer is 15-50% by weight, and(4) the flexural modulus of the copolymer is 2,500-7,000 kg/cm.sup.2.