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: Provided herein is a propylene-ethylene copolymer composition which comprises (a) 10 to 25 parts by weight of a first propylene-ethylene copolymer containing 90 wt % or more of ethylene and (b) 75 to 90 parts by weight of a second propylene-ethylene copolymer containing 0.5 to 2.5 wt % of ethylene, the first copolymer having intrinsic viscosity of .eta..sub.a and the second copolymer having an intrinsic viscosity of .eta..sub.b, said intrinsic viscosities being defined by .eta..sub.a -.eta..sub.b =-0.2 to +1.2 dl/g.

Abstract: A thermoplastic resin composition having excellent heat resistance and impact resistance as well as having excellent rigidity, chemical resistance and processibility, comprising:(a) a polyphenylene ether resin or a resin composition containing a polyphenylene ether,(b)(i) a modified propylene polymer grafted with a styrene-based monomer and an unsaturated carboxylic acid or its derivative, or(ii) a propylene-based resin composition containing the modified propylene polymer and a propylene polymer, and(c) a rubbery substance. The thermoplastic resin compositions not only have good mold-processibility but also exhibit well-balanced physical properties when molded into articles.

Abstract: A process for producing a highly transparent and highly stiff polypropylene affording a superior molded product is provided,which process comprises using a catalyst obtained by combining1 a titanium trichloride composition (III) obtained by reacting TiCl.sub.4 with an organoaluminum compound (A.sub.1) or a reaction product (I) or (A.sub.1) with an electron donor (B.sub.1) to obtain a solid product (II), followed by subjecting the product (II) to a multi-stage polymerization treatment with a linear olefin and a non-linear olefin, each once or more times used, and further reacting the resulting linear olefin-non-linear olefin block copolymer with an electron donor (B.sub.2) and an electron acceptor,2 an organoaluminum compound (A.sub.2); and as a third component,3 an aromatic carboxylic acid ester (E) or an organosilicon compound (S) having a Si--O--C bond and/or a mercapto group.

Abstract: Disclosed are thermoplastic resin compositions comprising:(a) a polyphenylene ether resin or a resin composition containing a polyphenylene ether,(b) (i) a modified propylene polymer obtainable by grafting a propylene polymer with a styrene-based monomer or a mixture of a styrene-based monomer and a monomer copolymerizable with the styrene-based monomer or (ii) a composition comtaining said modified propylene polymer and a propylene polymer, and(c) a rubbery substance,wherein the number mean particle size of the component (a) and (c) in the dispersion phase being from 0.01 to 20 .mu.m, the proportion of the component (a) to the sum of the components (a) and (b) being 1 to 80% by weight, that of the component (b) to the sum of the components (a) and (b) being 99 to 20% by weight, and the proportion of the component (c) to the sum of the components (a) and (b) being 1 to 50 parts by weight per 100 parts by weight of (a) plus (b).

Abstract: Disclosed herein is a thermoplastic resin composition which comprises:(a) a polyphenylene ether resin or a polyphenylene ether-containing resin composition,(b) a polypropylene grafted with a styrene-based monomer and/or a propylene copolymer grafted with a styrene-based monomer,(c) an ethylene-.alpha.-olefin copolymer grafted with a styrene-based monomer, said ethylene-.alpha.-olefin copolymer having a density of 0.85-0.91 g/cm.sup.3 and a maximum melting peak temperature of 100.degree. C. and above measured with a differential scanning calorimeter (DSC), and(d) optionally, rubbery substance. Also disclosed herein is a process for producing a thermoplastic resin composition which comprises incorporating a preblend composed of:(a') a polyphenylene ether resin or a polyphenylene ether-containing resin composition,(b') a polypropylene and/or a propylene copolymer,(c') an ethylene-.alpha.-olefin copolymer having a density of 0.85-0.91 g/cm.sup.3 and a maximum melting peak temperature of 100.degree. C.

Abstract: Disclosed is a thermoplastic resin composition, comprising:(a) a polyphenylene ether resin or a resin composition containing a polyphenylene ether,(b) (i) a modified propylene polymer obtainable by grafting a propylene polymer with a styrene-based monomer or a mixture of a styrene-based monomer and a monomer copolymerizable with the styrene-based monomer or (ii) a composition containing said modified propylene polymer and a propylene polymer, and(c) two or more rubbery substances, at least one rubbery substance being compatible with the component (a), and at least one rubbery substance being not compatible with the component (a). The thermoplastic resin composition has good moldability and yields molded articles having well-balanced physical properties.

Abstract: Impact-modified polymeric materials are produced by visbreaking certain reactor blends. In a preferred embodiment, impact-modified polypropylene materials are produced by visbreaking a reactor blend of polypropylene and thermoplastic polyethylene. The polypropylene material is preferably homopolypropylene having a melt flow rate of less than about 1 dg/min. Such impact-modified polymeric materials manifest unexpected compatibility characteristics, increased impact resistance at low temperatures, improved antiblush characteristics and improved flow characteristics.

Abstract: A process for producing a propylene polymer having good flowability with an MFR of at least 10 g/10 minutes comprises a first polymerization stage consisting of at least two steps and a subsequent second polymerization stage. It is important to control the intrinsic viscositites of a crystalline propylene polymer obtained from the first step of the first polymerization stage and a crystalline propylene polymer obtained from the final step of the first polymerization stage.

Abstract: A solid catalyst component for .alpha.-olefin polymerization containing as catalyst components at least titanium, magnesium and chlorine which are impregnated into an organic porous polymer carrier having a mean particle diameter of 5 to 1,000 .mu.m and a pore volume of 0.1 ml/g or above at a pore radius of 100 to 5,000 .ANG., a catalyst system comprising at least said solid catalyst component (A) and an organoaluminum compound (B), as well as a process for producing .alpha.-olefin polymers using said catalyst system.

Abstract: Slit film yarn based on propylene polymer, resistant to postfibrillation. The propylene polymer is a block copolymer of propylene and ethylene made up of chain segments consisting of propylene homopolymer and of chain segments consisting of random copolymer of propylene and ethylene.This slit film yarn is suitable for the manufacture of synthetic lawn.

Abstract: A thermoplastic olefin comprising an alloy of an olefin copolymer elastomer and a propylene/comonomer random copolymer is provided. The comonomer is selected from one or more of ethylene and C.sub.4 to C.sub.10 alpha-olefins. Polypropylene is an optional component of the alloy. The alloy may be produced by melt blending, reactor blending or a combination thereof, of the various components.

Abstract: Propylene/ethylene polymers are prepared by a process in which, in each case in the presence of hydrogen and by means of gas phase polymerization, first (A), in a first polymerization zone, propylene is homopolymerized, and the resulting propylene homopolymer is introduced into (B) a second polymerization zone, where a mixture of propylene and ethylene is then polymerized with the reaction product obtained in (A). In this process, ethylene is homopolymerized in a further polymerization zone (C), likewise by gas phase polymerization, with certain provisos, and the resulting reaction product is likewise fed to the second polymerization zone (B).

Abstract: Disclosed is a polymer alloy consisting essentially of a composition of a polyphenylene ether, a crystalline propylene resin, and an alkenyl aromatic monomer modified propylene-dialkenylbenzene compound copolymer. The composition excels in heat resistance and resistance to oils.

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 for producing a propylene-.alpha.-olefin block copolymer, which comprises polymerizing propylene in the presence of a catalyst and then polymerizing in a gas phase an .alpha.-olefin other than propylene, or propylene and other .alpha.-olefin without deactivating the catalyst, wherein at least one compound selected from the group consisting of an aromatic carboxylic acid ester, a phosphorous ester, an unsaturated dicarboxylic acid diester, an amine compound and an amide compound, is supplied to the latter gas phase polymerization system.

Abstract: Propylene/ethylene block copolymers are prepared by a continuous process in which, in each case in an agitated fixed bed of finely divided polymer from the gas phase, first (I) in a first polymerization zone, propylene is homopolymerized by feeding in a Ziegler-Natta catalyst system consisting of (1) a titanium component which contains titanium, magnesium, chlorine and a phthalic acid derivative, (2) an aluminumalkyl component and (3) a silane component, and (II) in a second polymerization zone, a mixture of propylene and ethylene is polymerized with the propylene homopolymer present in the reaction mixture obtained in the first polymerization zone by feeding in the said reaction mixture. In the process, (A) a titanium component (1) is used which is obtained by a method in which (1.1) first, (1.1.1) in a liquid hydrocarbon, (1.1.2) a finely divided magnesium halide, (1.1.3) an alkanol, (1.1.4) a certain phthalic acid derivative and (1.1.

Abstract: A block copolymer of polyalkylene and halogenated polystyrene comprises the formula:S'--A--(A--S').sub.min which m is 0, 1, 2, 3 or 4, A is a saturated polyalkylene, and S' is a nuclear brominated polystyrene having from about 0.5 to about 5 bromines per styrene unit. The polystyrene blocks are substantially free of halogen other than bromine and chlorine, and the polyalkylene is substantially free of halogen. The compositions retain the elastomeric properties of the non-halogenated form of the compounds while having significantly reduced flammability.

Abstract: The present invention relates to novel copolymers of alpha-olefins comprised of intramolecularly heterogeneous and intermolecularly homogeneous copolymer chains.

Abstract: A modified polypropylene having a substantially isotactic homopolypropylene and a propylene/olefin random copolymer, the modified polypropylene including up to about 50 chain disruptors per 1000 propylene repeat units. The chain disruptors are racemic polypropylene diads and olefin, the olefin being incorporated into the high end of the molecular weight distribution of the modified polypropylene.

Abstract: The present invention relates to a propylene polymer composition comprising:65 to 95% by weight of a propylene homopolymer having (a) an intrinsic viscosity ([.eta..sub.1 ]) of 0.5 to 3.5 dl/g, (b) a xylene soluble content at ordinary temperature (Xs) of not more than 3% by weight, and a difference (.DELTA.[.eta..sub.1 ]) between ([.eta..sub.1 ]) of xylene insoluble portion at the ordinary temperature and ([.eta..sub.1 ]) of xylene soluble portion at the ordinary temperature of not more than 0.5 dl/g, (c) an isotactic pentad fraction (IP) falling within the range represented by the following equation:IP.gtoreq.-0.624[.eta..sub.1 ]+97.5,and (d) a crystallization temperature (Tc) falling within the range represented by the following equation:Tc.gtoreq.-2.33[.eta..sub.1 ]+116.0;and5 to 35% by weight of a propylene-ethylene random copolymer having (e) an intrinsic viscosity ([.eta..sub.2 ]) of less than 2.8 dl/g and (f) an ethylene content of 10 to 35% by weight.

Abstract: The present invention relates to a propylene polymer composition comprising:60 to 94% by weight of a propylene homopolymer having (a) an intrinsic viscosity ([.eta..sub.1 ]) of 0.5 to 5 dl/g, (b) a xylene soluble content at ordinary temperature (Xs) of not more than 3% by weight, and a difference (.DELTA.[.eta..sub.1 ]) between ([.eta..sub.1 ]) of xylene insoluble portion at the ordinary temperature and ([.eta..sub.1 ]) of xylene soluble portion at the ordinary temperature of not more than 0.5 dl/g, (c) an isotactic pentad fraction (IP) falling within the range represented by the following equation:IP.gtoreq.-0.624[.eta..sub.1 ]+97.5,and (d) a crystallization temperature (Tc) falling within the range represented by the following equation:Tc.gtoreq.-2.33[.eta..sub.1 ]+116.0; and6 to 40% by weight of a propylene-ethylene random copolymer having (e) an intrinsic viscosity ([.eta..sub.2 ]) of not less than 2.8 dl/g and (f) an ethylene content of 30 to 80% by weight.

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 novel block copolymer consisting essentially of ethylene and propylene and comprising 1 to 20 parts by weight of block (A) having an ethylene content of 0 to 4% by weight, 5 to 49 parts by weight of block (B) having an ethylene content of more than 4% and less than 25% by weight, and 50 to 94 parts by weight of block (C) having an ethylene content of 25 to 85% by weight. The block copolymer is characterized by less formation of flow marks in molding, and also has excellent tensile characteristics.

Abstract: A process for the production of a product comprising ethylene/propylene copolymer incorporated into a matrix of propylene homopolymer or copolymer comprising the following steps:(a) contacting propylene or propylene and at least one alpha-olefin having 2 to 8 carbon atoms, and hydrogen, wherein the alpha-olefin is present in a ratio of about 0.01 to about 0.06 mole of alpha-olefin per mole of propylene and the hydrogen is present in a ratio of about 0.001 to about 0.

Abstract: Nodular copolymer and method of preparing a nodular copolymer by preparing a copolymer chain and coupling it with a coupling agent. The copolymers which form the nodular copolymer are formed of first and second segments, of which the second segments, containing the coupling agent, react to form the nodular region. The nodular copolymer is particularly useful as a lube oil additive.

Abstract: A novel low-crystalline propylene random copolymer composition comprising[I] 60 to 95% by weight of a propylene random copolymer and[II] 5 to 40% by weight of a low-crystalline propylene random copolymerwhich has excellent heat-sealability, heat-seal imparting property, transparency and antiblocking property and containing a reduced amount of a hydrocarbon-soluble component, a process for production thereof, and polypropylene composite laminated structure having improved heat-sealability and heat seal strength at low temperatures.

Abstract: A process for the production of .alpha.-olefin block copolymer particles having excellent impact resistance at low temperature and excellent molding and processing characteristics, is disclosed. The process includes a two step gas phase polymerization procedure under specific conditions in the presence of a specific catalyst system.

Abstract: The present invention relates to novel copolymers of alpha-olefins comprised of intramolecularly heterogeneous and intermolecularly homogeneous copolymer chains.

Abstract: The invention relates to a process for the controlled polymerization of alpha-olefins selected from the group consisting of propylene and butylene in order to form a polymer containing by weight about 10% to 30% isotactic polyolefin, 25% to 70% atactic polyolefin and 0% to 65% by weight of an amorphous ethylene/olefin copolymer which process comprises combinations of the steps of:(a) homopolymerizing the alpha-olefin at a temperature of from about 0.degree. C. to about 90.degree. C. (preferably from about 20.degree. C. to about 60.degree. C.) in the presence of a high yield catalyst comprising a titanium compound supported on activated MgCl.sub.

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: A process for continuously producing a propylene-ethylene block copolymer having well-balanced qualities such as high-impact properties, stiffness, processability, etc., with a good productivity, through two polymerization stages using a stereoregular catalyst comprising a Ti-containing solid catalyst and an organoaluminum compound, is provided, which process is characterized in that at the first stage, propylene is mainly fed into two or more polymerization vessels connected in series, to produce 60 to 95% by weight of the total polymerization quantity, and at the second stage, a specified quantity of a glycol ether is added to the polymerization reaction mixture obtained above and ethylene is fed in a relatively large quantity into one or more polymerization vessels, to produce 5 to 40% by weight of the total polymerization quantity.

Abstract: Block copolymers of ethylene and/or alpha-olefins, in particular propylene, with vinyl aromatic monomers, comprising at least two polymeric blocks, one of which being a polyolefinic block and the other having a stereoregular structure and being formed by vinyl aromatic monomer units.

Abstract: A continuous polymerization process for producing a high-melt viscoelastic ethylene-propylene copolymer by the use of Ziegler-Natta catalyst, which process make it possible to stably produce an ethylene-propylene block copolymer having superior physical properties suitable to sheet molding and blow molding and capable of producing large-size molded products is provided,which process comprises(a) feeding propylene and ethylene in a weight proportion of ethylene in the total of propylene and ethylene of 0-5% into 3 or more polymerization vessels among 4 or more polymerization vessels connected in series, to carry out continuous polymerization step (i) and successively feeding ethylene and propylene in a weight proportion of ethylene in the total of ethylene and propylene of 10-100% into one or more polymerization vessels, to carry out continuous polymerization process (ii); (b) feeding the total quantity of the catalyst only to the first polymerization vessel; (c) feeding the total quantity of hydrogen substant

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: The present invention relates to a multistage, continuous process for the preparation of propylene-ethylene impact copolymers comprising the use of a recirculating pipe-loop reactor for homopolymerizing propylene, a cyclone separator for removing fines, a gas-phase fluidized bed reactor for additional propylene homopolymerization, and a gas-phase fluidized bed reactor for propylene/ethylene copolymerization.

Abstract: The present invention relates to a multistage, continuous process for the preparation of propylene-ethylene impact copolymers comprising the use of a plug flow pipeline reactor for homopolymerizing propylene, a gas-phase fluidized bed reactor for additional propylene homopolymerization, and a gas-phase fluidized bed reactor for propylene/ethylene copolymerization.

Abstract: A process for producing a propylene block copolymer in the presence of a highly stereospecific olefin polymerization catalyst which comprises producing a crystalline polymer or copolymer of propylene in a first stage and random-copolymerizing propylene and another alpha-olefin in a mole ratio of from 10:90 to 90:10 in the presence of the propylene polymer or copolymer in a second stage; wherein in the random copolymerization, 0.0001 to 0.5 mole, per gram atom of aluminum in the catalyst, of an oxygen-containing compound being gaseous in a standard condition or 0.001 to 1 mole, per gram atom of aluminum in the catalyst, of an active hydrogen-containing compound being liquid or solid in a standard condition is fed into the random-copolymerization reaction system.

Abstract: Disclosed are polypropylene compositions having high impact resistance at low temperatures, and improved whitening resistance. They comprise:(a) 60-90 parts by weight of polypropylene with an isotacticity index >90; and(b) 10-40 parts by weight of an ethylene/butene-1 polymeric mixture containing 50-95% by weight of polymerized ethylene, and consisting essentially of:20-95% by weight of a crystalline fraction (I) with crystallinity of the polyethylene type, that is insoluble in xylene at 23.degree. C.; and5-80% by weight of an ethylene/butene-1 amorphous copolymeric fraction (II), that is soluble in xylene at 23.degree. C., and contains 40-70% by weight of ethylene;and in which the weight ratio between total polymerized ethylene and the amorphous fraction (II) is 0.6-8.

Abstract: A process for producing a propylene copolymer having improved transparency and rigidity, which comprises carrying out (A) the polymerization of a vinyl cycloalkane having at least 6 carbon atoms and (B) the polymerization of propylene either alone or with ethylene in a multiplicity of steps in the presence of a catalyst system composed of a titanium compound and an organoaluminum compound. The content of the vinyl cycloalkane unit in the resulting copolymer is 0.05 to 10,000 weight ppm.

Abstract: The invention concerns elastomeric copolymers of ethylene and propylene wherein the proportion by weight of units derived from ethylene is from 34 to 67% and the proportion by weight of units derived from propylene is from 33 to 66%. The copolymers are characterized in that 60% at least of the units derived from propylene are disposed in sequences of at least three successive units and that their fusion enthalpy, as measured after a given heat treatment, is lower than 15 cal/g (calories per gram) and in most cases is from 5 to 10 cal/g. The copolymers of the invention can be used in particular for the production of isotactic polypropylene compositions.

Abstract: Polypropylene interior parts for autocars having overcome the drawback of their permanent bulge or secondary deformation due to high temperature exposure is provided, which parts are obtained by molding a material comprising a propylene-ethylene block copolymer prepared by polymerizing propylene at a first stage so that the resulting propylene homopolymer can have a relation between its isotactic pentad ratio (P) and MFR of1.00.gtoreq.P.gtoreq.0.015 log MFR+0.955and can occupy 70 to 95% by weight of the total polymerization quantity, followed by polymerizing ethylene or ethylene and propylene in 30 to 5% by weight of the total polymerization quantity at at least one stage, so as to give an ethylene content occupying 3 to 12% by weight of the total polymerization quantity.

Abstract: A high-rigidity, whitening-resistant ethylene-propylene copolymer is provided, which is obtained by copolymerizing propylene with ethylene at three successive stages wherein at the respective first, second and third stages, a copolymer fraction having a specified ethylene content is formed in a specified amount based on the total polymerization amount, in the presence of a catalyst obtained by reacting an organoaluminum compound (L) or a reaction product thereof with an electron donor (E) with TiCl.sub.4 ; reacting the resulting solid product (I) with an (E) and an electron acceptor; and combining the resulting solid product (II) with an (L) and an aromatic carboxylic acid ester (R), the molar ratio of (R) to (II) being specified, and in the presence of hydrogen.

Abstract: Olefinic polymers characterized by the presence of free carboxylic groups arranged along the polymeric chain, obtained by radicalic grafting of unsaturated carboxylic acids onto the chain of the olefinic polymer. The products so obtained exhibit in particular a high adhesion to metals. The manufacturing process is based on the use of at least two different organic peroxides, having different reactivities.

Abstract: A polypropylene molding composition with a good hardness and good impact strength at low temperatures is formed by two-stage polymerization of propylene and ethylene in liquid propylene in the presence of a special supported catalyst.

Abstract: A propylene-ethylene block copolymer from which molded products having high rigidity and superior high-impact properties can be prepared even without adding any particular additive, is provided, which copolymer is obtained by (i) polymerizing propylene in 70 to 95 weight % based on the total polymerized amount, using a catalyst obtained by reacting an organoaluminum compound (I) or a reaction product of (I) with an electron donor (A), with TiCl.sub.4, further reacting the resulting solid product (II) with (A) and an electron acceptor (B), and combining the resulting solid product (III) with an organoaluminum compound (IV) and an aromatic carboxylic acid ester (V), the molar ratio of (V) to (III) being 0.1 to 10.0, and then (ii) polymerizing ethylene or ethylene and propylene in 30 to 5 weight % based on the total polymerized amount, at one or more stages, using the same catalyst as above, the ethylene content being 3 to 20 weight % based on the total polymerized amount.

Abstract: A process for producing a propylene block copolymer by a three-step reaction in the presence of a stereoregular catalyst. At the first step, propylene is polymerized at a temperature of 55.degree. C. or more to form polypropylene having an intrinsic viscosity of from 0.5 to 3.5 in the prescribed amount. At the second step, propylene is polymerized at a temperature of from 30.degree. to 90.degree. C. to form polypropylene having an intrinsic viscosity of at least 4 in the prescribed amount. And at the third step, ethylene and propylene are copolymerized at a temperature of from 30.degree. to 90.degree. C. to form an ethylene-propylene copolymer having an intrinsic viscosity of at least three in the prescribed amount. The propylene block copolymer formed by the three steps is superior and well balanced in impact resistance and stiffness.

Abstract: A process for producing a chemically blended propylene polymer composition having an ethylene content ranging from 3 to 40% by weight and being greater than the weight of the rubbery propylene copolymer formed in stage (II) below, which comprises the following stages (I) and (II):(I) a first stage of polymerizing propylene containing 0 to 5 mole % of another olefin in the presence of a catalyst composed of (A) a solid titanium catalyst component consisting essentially of titanium, magnesium, halogen, and an electron donor, (B) an organoaluminum compound, and (C) an organic silicon compound having an Si--O--C bond or an Si--N--C bond to thereby form a crystalline propylene polymer or copolymer; and(II) a second stage of polymerizing propylene and ethylene, or propylene, ethylene and another olefin in the presence of the reaction product of the first stage and the same catalyst as used in the first stage to form a rubbery propylene copolymer and a crystalline ethylene polymer or copolymer.

Abstract: A process for the preparation of ethylene-propylene impact copolymers at improved catalyst productivity rates involving the formation of a propylene prepolymer by polymerization of propylene in liquid phase in the presence of a catalyst system containing titanium halide supported on magnesium halide and aluminum alkyl complexed with an electron donor. Ethylene and propylene are block polymerized onto the prepolymer in a vapor phase reaction zone in the presence of a second catalyst system comprising a solution of a C.sub.5 -C.sub.9 polyalpha-monoolefin/catalyst/diluent.

Abstract: Improved impact modifier composition comprising elastomeric impact modifier polymer and dunkelsperser in a weight ratio of about 99.5/0.5 to 96/4 which is subject to substantially reduced gel formation in rigid thermoplastic matrix polymer formulations. Also disclosed are such formulations, as well as processes for preparing the improved impact modifier compositions.