Abstract: The present invention relates to grafted ethylene polymers and copolymers characterized in that they are thermoplastic and, if appropriate, crosslinkable and soluble at ambient temperature in organic solvents and/or aqueous media and in that they are prepared by polymerization of (in % by weight relative to the resin obtained):0.5 to 30% of at least one unoxidized polyethylene and/or an unoxidized ethylene copolymer based on at least 70% by weight of ethylene, the said polyethylene or ethylene copolymer being defined by the following properties:a weight average molecular weight (Mw) between 900 and 60,000,a Brookfield viscosity at 190.degree. C. of between 0.1 and 500 poises and/or a Brookfield viscosity at 140.degree. C. of between 0.1 and 2,000 poises.a crystallinity, measured using X rays, of between 10% and 80%,and, if desired, containing ester, anhydride or acid functional groups originating from the ethylene comonomers,70 to 99.

Abstract: New resins based on oxidized polyethylene, which are thermoplastic or thermosetting, soluble in solvents and/or aqueous media, are characterized in that they consist essentially of grafted polyethylene obtained by preparing a dispersion of a molten oxidized polyethylene in an organic solvent medium at a temperature above the softening range of the oxidized polyethylene. The oxidized polyethylene is employed in a proportion of 0.5 to 30% by weight of the resin and has a weight average molecular weight of between 900 and 25,000 and also contains side groups ending in functional groups capable of giving rise to free radicals. The dispersion is polymerized with a mixture of catalyzed monomers consisting essentially of acrylic and/or methacrylic monomers, in a proportion of 70 to 99.5% by weight based on the resin, the mixture being added gradually during the reaction.The resins according to the invention can be employed as a binder for coatings in paints, varnishes, glues, inks, adhesives and sealants.

Abstract: A crosslinking process wherein at a temperature of about 10.degree. to 160.degree. C., under a pressure of about 1 to 300 bars and for at least about 0.5 hour, a polymer, containing from about 42 to 99% by weight of units derived from ethylene and, where appropriate, also from an .alpha.-olefin, from about 1 to 8% by weight of units derived from maleic anhydride and from 0 to about 50% by weight of units derived from at least one additional monomer selected from an ester of an unsaturated carboxylic acid with an alcohol containing from 1 to 12 carbon atoms, is reacted with at least one polyepoxide compound, preferably present in an amount of from about 1 to 10 parts by weight, based on 100 parts by weight of the polymer, in the presence of at least one catalyst suitable for reacting the anhydride functions with the epoxide functions. The catalyst is preferably present in an amount from about 0.02 to 2 parts by weight, based on 100 parts by weight of the polymer.

Abstract: A crosslinking process wherein at a temperature of about 10.degree. to 160.degree. C., under a pressure of about 1 to 300 bars and for at least about 0.5 hour, a polymer, containing from about 42 to 99% by weight of units derived from ethylene and, where appropriate, also from an .alpha.-olefin, from about 1 to 8% by weight of units derived from maleic anhydride and from 0 to about 50% by weight of units derived from at least one additional monomer selected from an ester of an unsaturated carboxylic acid with an alcohol containing from 1 to 12 carbon atoms, is reacted with at least one polyepoxide compound, preferably present in an amount of from about 1 to 10 parts by weight, based on 100 parts by weight of the polymer, in the presence of at least one catalyst suitable for reacting the anhydride functions with the epoxide functions. The catalyst is preferably present in an amount from about 0.02 to 2 parts by weight, based on 100 parts by weight of the polymer.

Abstract: A process and apparatus for widening the molecular distribution of ethylene polymers produced at high pressure and at high temperature by polymerizing ethylene at a pressure between 600 and 3,000 bars and at a temperature between 160.degree. C. and 320.degree. C., in two reactors operating in parallel. In the first reactor, the reaction takes place in the presence of less than 0.1% of hydrogen for the purpose of producing a polymer of high molecular weight. In the second reactor, the reaction takes place in the presence of 0.2 to 5% of hydrogen for the purpose of fabricating a polymer of low molecular weight. The effluents from these two reactors are expanded and then moved to a set of two separators interconnected so as to efficiently mix the polymers produced in the two reactors by recycling the least possible amount of hydrogen into the supply circuit of the first reactor in such manner that the proportion of hydrogen in the first reactor remains less than 0.1% in moles.

Abstract: A process and apparatus for widening the molecular distribution of ethylene polymers produced at high pressure and at high temperature by polymerizing ethylene at a pressure between 600 and 3,000 bars and at a temperature between 160.degree. C. and 320.degree. C., in two reactors operating in parallel. In the first reactor, the reaction takes place in the presence of less than 0.1% of hydrogen for the purpose of producing a polymer of high molecular weight. In the second reactor, the reaction takes place in the presence of 0.2 to 5% of hydrogen for the purpose of fabricating a polymer of low molecular weight. The effluents from these two reactors are expanded and then moved to a set of two separators interconnected so as to efficiently mix the polymers produced in the two reactors by recycling the least possible amount of hydrogen into the supply circuit of the first reactor in such manner that the proportion of hydrogen in the first reactor remains less than 0.1% in moles.

Abstract: Ethylene is polymerized, in the presence of hydrogen, at a temperature of 180.degree. to 340.degree. C and a pressure of 200 2,500 bars with a Ziegler catalyst in a stirred reactor having at least one first reaction zone and at least one second reaction zone. The reaction mixture is fed to a separator at a pressure of 80 to 400 bars. The improvement results from partially liquifying at least a part of the gas coming from the separator at a temperature of -50.degree. to +20.degree. C, releasing the pressure to a value of 10 to 60 bars, separating the partially liquified gas into a gas phase and a liquid phase, and recycling the gas phase to the second reaction zone and the liquid phase to the first reaction zone. The resulting polymer has a low melt index, a high polydispersity index, and superior physical properties compared to polymers prepared by conventional processes.

Abstract: Modified copolymers which have viscosities which vary very markedly with changes in temperature are obtained by malaxating a statistical copolymer of ethylene and maleic anhydride containing between 0.5 and 20% by weight of units derived from maleic anhydride and having a melt index of between 0.1 and 500 dg/min, in the molten state with at least one chemical reagent containing at least two reactive groups which are amine or alcoholic --OH groups but at most primary or secondary amine group and at least one alcoholic --OH group.