Abstract: The present invention relates to high molecular weight homopolymers and copolymers of ethene, which homopolymer or copolymer is obtained by polymerizing the monomer(s) at a temperature of from 70.degree. to 150.degree. C. and under a pressure of from 2 to 150 bar in contact witha chromium trioxide catalyst,(1) loading a support based on silicon dioxide with(2) either chromium trioxide or a chromium compound capable of being converted to chromium trioxide under the conditions of stage (3) below and then(3) heating the resulting intermediate in a gas stream containing oxygen,the support (1) being a special silica xerogel obtained by extracting not more than 30% of the water from a silica hydrogel by means of an alkanol, an alkanone or a mixture thereof followed by drying, comminution and fractional screening.

Abstract: A novel Phillips catalyst for the homopolymerization of ethylene and the copolymerization of ethylene with .alpha.-olefins contains, as a catalytically active component, a chromium catalyst supported on a finely divided aluminum silicate gel, modified with a fluoride and activated in an oxidizing atmosphere at elevated temperatures. The finely divided aluminum silicate gel (carrier gel) used here has an alumina content of from 0.5 to 6% by weight, the alumina being concentrated in the surface region of the carrier gel particles. The novel Phillips catalyst has high productivity and gives high molecular weight ethylene homopolymers and copolymers which have excellent low temperature impact strength and do not tend to swell in the blow molding process on emergence from the extruder die.

Abstract: In a novel process for the preparation of a supported catalyst for the polymerization of .alpha.-olefins, a carrier gel (1) is first prepared by a method in which a sodium or potassium waterglass solution is introduced into a stream of an aqueous mineral acid which is subjected to angular momentum and may contain aluminum ions, longitudinally and tangentially to the stream, the resulting silica hydrosol sprayed in the form of drops into a gaseous medium and allowed to solidify into a hydrogel, and the resulting hydrogel is freed from salts by washing without prior aging and, if necessary, freed from some of the water by extraction with alcohols and/or ketones and is then dried. This gives the carrier gel (1), which is milled and is fractionated according to particle size. In a second process step, the carrier gel (1) is laden with chromium trioxide or with a chromium compound which can be converted into chromium trioxide, after which the resulting chromium-containing carrier gel (2) is heated at from 400.

Abstract: In a process for the peroxide-free grafting of ethylenically unsaturated carboxylic acids, carboxylic anhydrides and/or their derivatives to a homopolymer or copolymer of ethylene having a density equal to or greater than 0.930 g/cm.sup.3, the monomers to be grafted are used in a concentration of from 0.01 to 0.5% by weight and the grafting reaction is carried out at from 210.degree. to 300.degree. C. in a conventional extruder or mixer in the absence of a free radical initiator. The graft copolymers are used for the preparation of ionomers and adhesion promoters.

Abstract: In a process for the peroxide-free grafting of ethylenically unsaturated carboxylic acids, carboxylic anhydrides and/or their derivatives to a homopolymer or copolymer of ethylene having a density less than 0.930 g/cm.sup.3, the monomers to be grafted are used in a concentration of from 0.01 to 0.5% by weight and the grafting reaction is carried out at from 210.degree. to 300.degree. C. in a conventional extruder or mixer in the absence of a free radical initiator. The graft copolymers are used for the preparation of ionomers and adhesion promoters.

Abstract: The present invention relates to a novel catalyst for the preparation of high molecular weight homopolymers and copolymers of ethene, which catalyst is obtainable by(1) loading a support based on silicon dioxide with(2) either chromium trioxide or a chromium compound capable of being converted to chromium trioxide under the conditions of stage (3) below and then(3) heating the resulting intermediate in a gas stream containing oxygen.the support (1) being a special silica xerogel obtained by extracting not more than 30% of the water from a silica hydrogel by means of an alkanol, an alkanone or a mixture thereof followed by drying, comminution and fractional screening.

Abstract: Ethylenically unsaturated carboxylic acids and/or carboxylic anhydrides are grafted onto polyolefin blends by a process in which the polyolefin blend consists of from 5 to 49 parts by weight of an ethylene/propylene block copolymer having an ethylene content of less than or equal to 20% by weight and from 51 to 95 parts by weight of a homopolymer or copolymer of ethylene, and the resulting graft copolymer blends are used as adhesion promoters, in particular for polyethylene/adhesion promotor/steel composites, and for the preparation of ionomers.

Abstract: Ethene polymers are prepared by Phillips catalysis using (1) a supported catalyst which is loaded with chromium and titanium and (2) a co-catalyst, (1) having been obtained by preparing (1.1) a chromium- and titanium-loaded catalyst intermediate from (1.1.a) a silicate carrier material, (1.1.b) a selected chromium compound and (1.1.c) a selected titanium compound and then (1.2) heating said catalyst intermediate in an oxygen-containing gas stream, the (1) used having been obtained by, in general terms, (1.1) preparing in the first stage (1.1.1) a suspension from (1.1.1.1) a finely divided silicate carrier material and (1.1.1.2) a liquid alkane, (1.1.2) then (1.1.2.1) combining the suspension resulting from (1.1.1.) with (1.1.2.2.) a finely divided chromium trioxide, (1.1.3) thereupon (1.1.3.1) combining the suspension obtained from (1.1.2) with (1.1.3.2) an alkanol, (1.1.4) thereafter (1.1.4.1) combining the suspension formed in (1.1.3) with (1.1.4.2) a titanium compound of the formula Ti(OR).sub.

Abstract: Homopolymers and copolymers of ethene are prepared using a Ziegler catalyst system comprising (1) a transition metal catalyst component, (2) an organoaluminum catalyst component and (3) an organohalogen catalyst component, by a method in which the transition metal catalyst component (1) employed is a solid-phase product (VI) obtained by (1.1) first combining (1.1.1) an inorganic oxidic substrate (I), as the carrier, with (1.1.2) a solution (II) consisting of (IIa) a certain oxahydrocarbon and (IIb) a mixture of (IIb1) a vanadium trichloride/alcohol complex, (IIb2) a titanium trihalide or titanium trihalide/alcohol complex and, if required, (IIb3) a zirconium tetrahalide to form a suspension (III), evaporating down this suspension to form a solid-phase intermediate (IV), and (1.2) then (1.2.1) combining the solid-phase intermediate (IV) obtained from (1.1) with (1.2.

Abstract: A process for the manufacture of ethylene polymers by polymerizing ethylene under high pressures and at high temperatures in the presence of from 0.01 to 0.5 percent by weight of an alkyl ester (alkyl being of 1 to 8 carbon atoms) of an alkenemonocarboxylic acid of 3 or 4 carbon atoms. n-Butyl acrylate is a particularly suitable polymerization activator. Although the start temperature of the ethylene polymerization is relatively low, there is no difference in mechanical and optical properties of a blown film manufactured from the resulting ethylene polymer and of a blown film of pure polyethylene.

Abstract: The invention relates to a process for rapidly letting-down the pressure in continuous high pressure polymerization systems for the polymerization of ethylene. In this process, the let-down hot reaction mixture is passed into an expansion vessel in such a way that the jet of let-down hot reaction mixture issuing from the let-down line is led into the partially water-filled expansion vessel at an angle of from 0.degree. to 45.degree. to the water surface, so that the jet does not enter below the surface but must touch or strike it. The method described makes it possible to let the mixture down partially and thus to slow down the decomposition in the case of explosive decomposition reactions occurring in the polymerization system.

Abstract: Ethylene polymers are manufactured in a tubular reactor under high pressure and at high temperatures in the presence of polymerization initiators. The polymerization is carried out in two different zones of the reactor, a mixture of ethylene, oxygen and regulator being fed into the first zone and a co-initiator having a half-life temperature, measured in benzene, of above 140.degree. C being additionally fed into the second zone. The co-initiator may be a peroxide or a hydroperoxide. The melt index, or the haze and gloss of a film produced from the resulting ethylene polymer, can be varied advantageously through the choice of the co-initiator.

Abstract: Ethylene polymers are manufactured by polymerizing ethylene under high pressure at high temperatures in an autoclave reactor. The heat of reaction generated by the polymerization is removed, within the reactor, by a cooling system in which the cooling medium is ethylene; the pressure of the monomer in the cooling system should differ by from 0 to 200 bars from the pressure prevailing in the polymerization system, and the temperature of the monomer on entering the cooling system is at least 40.degree. C. lower than the temperature prevailing in the autoclave. The process permits an increase in the conversion achieved in the polymerization reaction.

Abstract: A process for the manufacture of copolymers of ethylene with vinyl acetate at pressures above 800 atmospheres and at from 150.degree. to 350.degree. C, using mean residence times of up to at most 100 seconds. The reaction mixture obtained from the polymerization is kept for from 2 to 10 minutes at from 150.degree. to 250.degree. C under a pressure below 500 atmospheres. Homogeneous ethylene/vinyl acetate copolymers are obtained without the formation of substantial amounts of free acetic acid by decomposition of the vinyl acetate.

Abstract: Ethylene polymers are produced at pressures between 1000 and 4000 atmospheres and temperatures of from 120.degree. to 300.degree. C in a reaction zone having an 1/d ratio of from 10:1 to 20:1 while shear forces act on the reaction mixture. The ethylene is fed continuously and radially to the reaction zone at a velocity of from 2 to 20 m/sec. The average residence time of the reaction mixture in the reaction zone is from 20 to 90 seconds. The products show a broad molecular weight distribution and are particularly advantageous for use as extruded coatings.