摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要翻译:在将烯键式不饱和羧酸,羧酸酐和/或其衍生物过氧化物接枝到密度小于0.930g / cm 3的乙烯的均聚物或共聚物的方法中,待接枝的单体的浓度为 在常规挤出机或混合器中,在不存在自由基引发剂的情况下,接枝反应在210-300℃下进行。 接枝共聚物用于制备离聚物和粘合促进剂。
摘要:
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.4, where R is alkyl, aryl or cycloalkyl, and (1.1.5) finally evaporating the suspension obtained in (1.1.4) to dryness, and then (1.2) in the second stage first (1.2.1) treating the catalyst intermediate obtained in the first state (1.1) with a nitrogen stream, thereupon (1.2.2) heating the intermediate obtained in (1.2.1) in an oxygen-containing gas stream, and finally (1.2.3) treating the intermediate obtained in (1.2.2) with a nitrogen stream; and as (2) with an alkyllithium.
摘要:
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.
摘要:
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 (1.2.2) a solution of an organoaluminum compound (V) to form a suspension, the resulting suspended solid-phase product (VI) being the transition metal catalyst component (1).
摘要:
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.