摘要:
In a process for the polymerization or copolymerization of ethylenically unsaturated monomers in the presence of polymerization initiators which decompose to form free radicals in a continuously operated polymerization apparatus comprising a fresh gas feed line, a precompressor, a postcompressor, a reactor, a pressure maintenance valve, a high-pressure circuit having a high-pressure product separator and a high-pressure circulation gas return line, a product valve and a low-pressure circuit having a low-pressure product separator and a low-pressure circulation gas return line, nitrogen monoxide or oxygen is introduced as inhibitor into the high-pressure circuit, into the low-pressure circuit and/or the precompressor.
摘要:
A process for compressing ethylenically unsaturated monomers at a pressure of 200-5000 bar in the absence of a polymerization initiator comprises carrying out compression in the presence of a sterically hindered amine derivative.
摘要:
A process for compressing ethylenically unsaturated monomers at a pressure of 200-5000 bar in the absence of a polymerization initiator comprises carrying out compression in the presence of a sterically hindered amine derivative.
摘要:
Disclosed is a process for pressurizing ethylenically unsaturated monomers to 200-5000 bar in the absence of a polymerization initiator, which comprises effecting said pressurizing in the presence of nitroxyl compounds of the formula I where R1 and R2 are singly C1-C4-alkyl or combine with the joining carbon atom to form a 5- or 6-membered saturated hydrocarbon ring, R3 is C1-C4-alkyl, and R4 is hydrogen or C1-C12-alkyl. Also disclosed are a process for preparing copolymers by such pressurization and subsequent polymerization and copolymers obtainable thereby.
摘要:
A process for preparing ethylene polymers by the high-pressure method comprises dissolving one or more free-radical initiators in one or more ketones of the formula I where R1 and R2 are identical or different and are selected from among C1-C6-alkyl and C3-C12-cycloalkyl and R1 and R2 may also be covalently linked to one another to form a 4- to 13-membered ring, prior to the polymerization, compressing the solution, metering it into the polymerization reactor at one or more points and subsequently carrying out the polymerization at from 150 to 380° C. and from 500 to 4500 bar.
摘要:
A process for preparing ethylene homopolymers and copolymers in a tubular reactor having two or more polymerization zones at temperatures of between 150° C. and 350° C. and pressures in the range from 500 to 5000 bar, using oxygen as initiator, which comprises using, as molar mass regulator, one or more aliphatic ketones of the formula I, where the variable R1 is a C1-C6-alkyl or C3-C12-cycloalkyl, ethylene homopolymers and copolymers obtainable therefrom and their user for producing injection-molded products in the cosmetics, medical and food sectors are described.
摘要:
A process for preparing ethylene polymers by the high-pressure method comprises dissolving one or more free-radical initiators in one or more ketones of the formula I where R1 and R2 are identical or different and are selected from among C1-C6-alkyl and C3-C12-cycloalkyl and R1 and R2 may also be covalently linked to one another to form a 4- to 13-membered ring, prior to the polymerization, compressing the solution, metering it into the polymerization reactor at one or more points and subsequently carrying out the polymerization at from 150 to 380° C. and from 500 to 4500 bar.
摘要:
In a process for preparing polyethylene waxes at from 200 to 350° C. and pressures in the range from 500 to 4 000 bar using molar mass regulators, a peroxide mixture comprising from 5 to 95% by weight of at least one cyclic peroxide of the formula I, where the radicals R are identical or different and are selected from among alkyl groups and aryl groups, is used as free radical initiator and a molar H2/ethylene ratio of from 1:2 000 to 1:40 000 is employed.
摘要:
The invention relates to a method and an apparatus for the polymerization of gaseous olefins, in particular of ethylene and at least one &agr;-olefin, in the gas phase in a stirred or fluidized, catalyst-containing polymerization zone (2) and at least one decompression zone (6, 10) downstream of the polymerization zone (2). The mixture of solid (co)polymer and unreacted monomers leaving the polymerization zone (2) flows through a settling zone, in particular in the form of a settling leg (14), before the decompression zone.
摘要:
In a process for producing Phillips catalysts in which an oxidic support material is treated in suspension with a chromium salt solution and subsequently, after removing the solvent, calcined in an oxygen-containing atmosphere at above 300° C., the oxidic support material and/or the catalyst after calcination are/is, according to the present invention, comminuted until a mean particle size of