DE1104699B - Process for the production of solid polyethylenes - Google Patents

Description

The subject of the main patent application is a process for the production of solid polyethylenes by polymerization of ethylene in an anhydrous liquid suspending medium in the presence of catalytically active titanium chlorides, which is characterized in that ethylene at increased pressure and optionally elevated temperature in the presence of titanium dichloride or one containing it Reaction mixture produced by reducing titanium tetrachloride to the titanium dichloride stage using aluminum or titanium is polymerized in the heat in a manner known per se. The one here The catalysts used are outside the polymerization room by heating the said Components shown at temperatures between 200 and 300 ° C. After the polymerization must then the catalyst can be separated from the polymer by treatment with solvents, since the Otherwise the end product is strongly colored and gives rise to signs of corrosion on the processing machines.

It has now been found that you can get an almost catalyst-free polyethylene directly and without special Work-up measures can be obtained if you put ethylene in an anhydrous liquid suspending agent at elevated pressure and temperature in the presence of a catalyst, which by reduction from titanium tetrachloride to titanium dichloride stage by means of aluminum or titanium in the heat in known Way is obtainable using a catalyst obtained by reducing titanium tetrachloride has been obtained on fixed aluminum or titanium in the reaction space and that resulting polymer after dissolution in the suspension medium at elevated temperature from the Reaction space removed. So there are catalysts used that, expediently in a pressure-resistant Flow tube, directly on the spot by heating metallic titanium or aluminum with titanium tetrachloride to temperatures z. B. from 200 to 300 ° C were produced. The catalytically effective one Titanium dichloride then forms a layer that adheres relatively firmly to the metallic support, on the surface of which the ethylene polymerizes. The polymerization temperature is chosen as follows high that the resulting polyethylene is dissolved, and pulls the resulting polymer solution continuously or discontinuously. The deposited polymer can pass through from the cooled solution Filtration, decanting, centrifuging or similar simple measures can be separated, whereby the recovered solvents immediately after a distillation to separate by-products in the process can be traced back.

Method of manufacture
of solid polyethylenes

Addition to patent application F 14922 IVb / 39 c
(Interpretation document 1 080 303)

Applicant:

Paint factories Bayer Aktiengesellschaft, Leverkusen-Bayerwerk

Dr. Gustav Pieper, Dr. Hans-Ferdinand Rickert,

Cologne-Stammheim,

and Dr. Eberhard Stein, Leverkusen,
have been named as inventors

The polymerization is particularly at pressures above 50 atmospheres and temperatures between 150 and 300 ° C carried out. Aliphatic, cycloaliphatic and aromatic hydrocarbons, e.g. B. petroleum ether, cyclohexane or xylene can be used. The solvent should be absolutely dry and as free of air as possible because otherwise the catalytic converter will be damaged. The semi-continuous mode of operation described in the examples has the advantage over the fully continuous that due to the pressure fluctuations when draining the viscous polymer solution also from the

4.0 pores of the catalyst is pressed out so that when filling the tube again and again fresh ethylene and solvent with the whole catalyst surface comes into contact.

The polymer which precipitates out when the drained solution cools down usually only contains so little Amounts of catalyst that it can easily be used for many purposes can. However, treatment with alcohols or dilute acids or else filtration can be used the hot polymer solution obtained an almost colorless, catalyst-free product.

The polyethylene produced by this process is characterized by a high pour point (NST value) and high tensile strength. It can e.g. B.

109 540/441

for the production of injection molded articles, pipes, plates and foils or in the electrical industry as insulating material be used.

example 1

A vertical, pressure-resistant steel tube with a clear width of 2 cm and a length of 55 cm was filled with aluminum turnings loosely filled. The tube was heated electrically and the temperature through a Thermocouple measured on the outside wall. A mixture of 50 ecm of titanium tetrachloride was poured into this tube and 100 ecm of paraffin oil were introduced, whereupon the tube was heated to 200 ° C. for 2 hours. Here, a coating of titanium dichloride was produced on the aluminum chips, which acts as a catalyst was used for the subsequent polymerization of ethylene.

For this purpose, ethylene was injected at the upper end of the tube at a pressure of 70 atm via a pressure equalization vessel fed and at the same time pumped in xylene as a solvent for the resulting polymer. You can then use a 1 to 2% solution of polyethylene at approximately every hourly intervals Drain through a tap at the lower end of the pipe. The polymer precipitated on cooling was sucked off and falls after boiling with alcohol (to remove entrained catalyst residues) as a colorless, fibrous mass. The solvent was removed by distillation in a vacuum evaporator cleaned and reused in the cycle. Table I below provides information on the amounts used and the yields achieved. At the end of each test section the aluminum chips by treatment with the reusable mixture of titanium tetrachloride and paraffin oil (2 hours at 300 ° C) regenerated. At the end of the series of tests, there were aluminum chips not yet consumed, so that a continuation of the polymerization is still possible would have been.

Technical data see table III.

Table I.

Lot temperature hours Xylene throughput liter
per hour yield Cjramm
per hour ⁰ C liter 0.400 Gram 2.0 a 250 7.5 3.0 0.46 15th 3.85 b 220 13th 6.0 0.533 50 2.3 C. 220 to 230 15th 8.0 0.38 35 2.0 d 250 20th 7.6 40

Example 2

In the same apparatus as in Example 1, 140 g of titanium sponge (grain size 5 mm) were treated with the titanium tetrachloride-paraffin oil mixture at 300 ° C. for 3 hours and then the ethylene was polymerized in the same way as in Example 1 (see Table II). In this case, the regeneration of the contact was only necessary after 62 operating hours and almost led to the initial yields being achieved. At the end of the test series, the titanium sponge was hardly changed, so that it can easily be reused with occasional regeneration.
Technical data see table III.

Table II

Lot temperature
⁰ C hours Xylene u
liter sentence
liter
per hour Aust
Gram > today
Gram
per hour a 255 to 260 17th 5.86 0.345 91 5.35 b 250 to 270 10.5 4.52 0.430 35 3.32 C. 250 to 280 24 8.50 0.352 55 2.30 d 260 to 280 21 5.67 0.270 38 1.80 e 250 to 270 21 8.41 0.400 75 3.58 f 280 to 290 23 4.82 0.210 85 3.70

The viscosity was determined in a falling ball viscometer at 125 ° C. in 1Voiger xylene solution. For standard methods were used for the remaining values.

Table III
Technical data for examples 1 and 2

example viscosity Tear
strength fracture
strain Pour point ?? rel kg / cm ² % NST value Ib 2.47 271 45 151 2a 3.54 279 640 137 2 B 4.20 287 373 150 2c 3.33 263 100 147 2d 3.28 268 250 150 2e 3.85 272 87 144 2f 3.74 263 70 145

Claims (2)

Patent claims: 1. Process for the production of solid polyethylenes by polymerizing ethylene in an anhydrous liquid suspending agent at elevated pressure and temperature in Presence of a catalyst produced by the reduction of titanium tetrachloride to the titanium dichloride stage by means of aluminum or titanium in the heat in a known manner, according to patent application F 14922 IVb / 39c (German Auslegeschrift 1 080 303), characterized in that one a catalyst is used that is produced by the reduction of titanium tetrachloride on fixed aluminum or titanium has been obtained in the reaction space, and the resulting polymer after Dissolution in the suspension medium removed from the reaction space at an elevated temperature. 2. The method according to claim 1, characterized in that the suspension medium used separated from the polymer after leaving the polymer chamber and returned to the polymer chamber. © 10 »540/441 4.61