DE1520113C - Process for the polymerization of ethylene - Google Patents

Description

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The polymerization of ethylene at high pressures, pressure concerns, the advantage of the process of generally above 500 at, with the help of free invention is that it is possible to use the usual radical-forming catalysts is known. There are high-pressure apparatuses for the production of high catalysts are known to use polyethylene having a density in their presence. Ethylene can be polymerized at atmospheric pressure 5 Here, high conversion rates can be achieved. That achieved by the low-pressure process, so that in certain cases even an ethylene has a higher density than that in the older ash removal of the product can be dispensed with. High pressure process produced polymer. In the British patent 799 392, the process of the invention results in a polyethylene, high-density catalysts, ie a polymer with a specific specification, which by mixing aluminum io fish weight of at least 0.935 at 20 ° C.
The preparation of the catalyst for the process in which the alkyl groups of the invention contain 2 to 12 carbon atoms is carried out by mixing the two with compounds of IV. to VI. Minor constituents are formed before injection into the ethylene poly group of the periodic table. This merization vessel in the presence or absence of catalysts is suitable for use with a hydrocarbon diluent. If atmospheric pressure, however, is stated that the ingredients are mixed too early before the injection with the effect of the catalysts basically the same, a precipitate can form, if the pressure is below a technically possible level before the catalyst is injected, and it represent value is increased. However, these catalysts develop the aforementioned disadvantages. The catalyst generally insoluble precipitates which are present in a 20 is conveniently prepared by making the two high pressure reaction vessels difficult to disperse constituents or their solutions are one. In continuous processes at high screw presses or other pumps, they cannot be used in pressures, since it is very difficult to mix and match suspensions of solids in liquid catalyst into the polymerization reactor under high pressures handle lines 25 will. The catalyst will preferably become clogged and the injection mechanism can be disrupted by abrasion reaction vessel within a minute of mixing. introduced. Injecting a catalyst mixture

In addition, in the French patent schung that no hydrocarbon as diluent 1161737 a process for the polymerization of medium contains, requires due to the higher Ethylene at pressures of at least 500 atm and a concentration of the catalyst is more careful Temperatures of at least 175 ° C by means of catalyst control than in the absence of a diluent of aluminum trialkylene and titanium tetrachloride means, but it has the advantage that that generated described. Those in the examples of the French polyethylene not with the lower boiling coal patent 1 161 737 specified catalyst hydrogen is contaminated and possible disadvantages combinations result in any case immediately 35 in the subsequent processing avoided who-Precipitation, so this procedure is the same as that. The catalyst is powered by oxygen and Has disadvantages as it decomposes above in relation to British water. For this reason, his patent specification 799 392 have been set out. After position in the absence or only in the very presence the information in the description of the said limited amounts of air and moisture by French Patent specification 1161 737 is supposed to be made of aluminum.

Miniumtrialkyl, including aluminum The polymerization can be according to any of the known

trimethyl come into question. But if in this process for the polymerization of ethylene at high

In the same way as in the examples, the pressure mentioned can be carried out. You can discount

Patent specification, the mixing of the catalyst work in a pressure-resistant container,

long before the actual use of the 45, however, there is the special advantage of the inventive

Catalyst takes place, a lower catalyst is also formed according to the fact that it is used

blow. useful in continuous reactions of the normal

The subject matter of the invention is a method of the type of technical manufacture that is sometimes used

for the polymerization of ethylene at pressures of over position of polyethylene can introduce. Such

450 at using catalysts that can run through 50 continuous reactions in either one

Mixing of aluminum trimethyl with titanium tetra stirred autoclave or in a reaction tube

chloride have been obtained, which is characterized by a large length compared to the cross-section

is drawn is that the catalyst can be carried out after mixing. In both cases, the

of the aluminum trialkyl with the titanium tetrachloride catalyst introduced at one or more points,

Immediately or in good time in the polymerization vessel 55 The polymer and unreacted ethylene

is introduced that the reaction mixture containing no precipitate is formed from the reac-

has. In the method of the invention, the catalyst vessel is through a pressure relief valve in a

Sator thus passed into the reaction vessel in liquid form separator, in which the ethylene from

injected. As soon as it entered the reaction vessel, the polymer was separated off and the feed gas

is splashed, it will easily 60 can be fed back into the reaction mass. The polymer can

dispersed. In this way, the disadvantages of being brought into an extruder and granulated or

Process of French patent 1161 737 can be converted to any other desired shape,

avoided. The molecular weight, the density, the fluid properties

Compared to the procedures of the Belgian patent shops and other properties of the product

543 941 and the German Auslegeschrift 65 depend mainly on the reaction conditions

1,026,964, which supports the use of aluminum genes, i.e. H. the temperature, the pressure and the

trimethyl and titanium tetrachloride produced cataly- essence or absence of modifiers,

Sators in the ethylene polymerization under low z. B. comonomers and chain transfer agents.

Claims (5)

Normally the temperature and the pressure are B is ρ ie 1 1
chosen so as to obtain a desired product obtained, and the quantitative ratio of catalyst to a 300 ml high pressure stirred autoclave Ethylene, which is used in the reaction, is mixed with dry, oxygen-free ethylene up to one controlled in such a way that the desired temperature 5 pressure of 450 at is charged and heated to 30 ° C, door or the temperature range at the exothermic After the desired conditions of pressure Response. The heat transfer is obtained to and the temperature will be lo- Mainly by the entering into the autoclave solutions of aluminum trimethyl (0.1 mmol / ml) and cool gas or, in the case of a tubular reaction vessel, titanium tetrachloride (0.1 mmol / ml) in n-heptane in the same Dissipation of heat caused by the wall. io chen volumes at the entry point of a spindle Preferably, the reaction temperature is allowed to mix, and the mixture is then in Do not exceed 100 ° C. Injected into the autoclave for economic reasons. Within a period of time If reaction temperatures of 30 to 80 ⁰ C were from 69 minutes, 32 ml of this mixture preferred. The reaction is injected at temperatures below. During this time the pressure was on 30 ⁰ C slows down, and the performance of the 15 at 450 to 600 at and the temperature at 30 to 65 ⁰ C Catalyst goes at temperatures kept above. After the autoclave and the 80 ° C lost. If you put the reaction in a pressure relief device, 79 g of solid polymer were removed. Carries out a stirred autoclave, one can separate the reac. The polymer had a density of 0.940 . tion vessel supplied ethylene, if necessary, at 2O ⁰ C. cool to provide adequate cooling. 20 B e i s η i e 1 2 If in the method according to the invention relatively low temperatures are used. _{The procedure of Example 1 was carried out using} The polymer tends to have an undesirably high _{consumption of} solutions of aluminum trimethyl Molecular weight and thus a low melting point _{(015 mmol / ml) and} titanium tetrachloride (0.018 mol / ml) to have flux mdex and poor processability. 25 _{in petroleum} ether repeated. Within a period of time This disadvantage can be overcome by _yon 3 _{hours, 18 ml of this} mixture in the polymerization is injected in the presence of a chain over _the autoclave. The pressure was at 890 Tragers carried out to the molecular weight of _{up to 1200 at and the temperature from 16 to} 370 _c generated polymer to reduce hydrogen is _held . _{There were 45 g of solid} polymer _{A 3 ° density of Q96Q at 2Q} o _{C was obtained} under the preferred reaction conditions.
suitable chain subcarrier. The separation of the catalyst residues from the Polyethylene produced can optionally be carried out by Example 3
Wash the polymer with a suitable one Complexing agents, e.g. B. an alcohol, ketone or 35 ^The procedure of Example 1 was carried out using Diketone, or a mixture of these compounds, uses solutions of aluminum trimethyl be performed. The metal residues react (0.15 mmol / ml) and titanium tetrachloride (0.026 mmol / ml) repeated with the complexing agent to form grain ether in petroleum ether. Within a period of time plexes, which one with each diluent, in ^y on 34 minutes were 12.5 ml of this mixture in which they are soluble, e.g. B. a hydrocarbon 40 injected into ^{the autoclave.} The pressure was at 950 or a further amount of the complexing agent, up to 1000 atm and the temperature at 68 to 79 ⁰ C. can wash out. However, it is kept a special one. There were 15 g of solid polymer Feature of the method of the invention that the density of 0.962 obtained at 2O ⁰ C,
conversion achieved (i.e., the moles polymerized Ethylene per mole of catalyst) under suitable conditions
conditions is so high that it is necessary for numerous Applications of the product not required The procedure of Example 1 was carried out using is to separate the catalyst residues. application of solutions of aluminum trimethyl The advantages of the method according to the invention (0.14 mmol / ml) and titanium tetrachloride (0.016 mmol / ml) consist, apart from those already mentioned, in _{repeating 50 J n of} a high-boiling gasoline fraction. that it is possible for the high pressure polyethylene producer within a period of 36 minutes to greatly expand its range of polyethylenes, injecting 24 ml of this mixture into the autoclave, without special machinery and equipment for manufacturing T _he pressure was at in 1750-2150 and the tem- position of higher density polyethylene. temperature kept at 30 to 110 ° C. There were 42 g This is an important advantage, since the products with 55 solid polymer have a density of 0.960 at 20 °. C. lower density that obtained after the conventional one.
Letterpress processes are still generated for
numerous uses are preferred. In addition, elasticity is desirable in the production, claims:
to a demand for these polymers 60 as well as the higher density polymers. 1. Process for the polymerization of ethylene to fill. when using pressures above 450 at In the examples below, the process of catalysts made by mixing of the invention on the basis of batchwise obtained by aluminum trimethyl with titanium tetrachloride guided experiments explained. It can be seen, however, 65 have been characterized that the catalyst in the same way in a continuous that the catalyst after mixing the A natural polymerization process is introduced with trimethyl aluminum with titanium tetrachloride can, which is carried out in the usual way. immediately or in good time in the polymerization 5 6 vessel is introduced so that there is still no precipitation mixing of the trimethyl aluminum with the has formed. Introduces titanium tetrachloride. 2. The method according to claim 1, characterized in 3. Method according to claim 1 or 2, characterized draws that the catalyst is in the poly- characterized in that at a temperature of merization vessel within 1 minute after the '5 at most 100 ⁰ C is polymerized.