FI58338C - FREEZING FOR POLYETHY WITH POLYETHYLES AND ENCLOSURES OEVER 500 000 - Google Patents

Description

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Patent · och registerstyrelsen '' Ameion utiigd oeh utUkrifwn pubUcured 30.09.80 (32) (33) (31) Pyydutty «tuolkuu» —Bugtrd prlorltut 11.12.73

Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) P 2361508.9 Proof-Styrkt (71) Ruhrchemie Aktiengesellschaft, Postfach 35 »* + 2 Oberhausen 13, Federal Republic of Germany-Förbundsrepubliken Tyskland (DE), Oberhausen, 72) Helmut, 72 Helmut Geiser, Oberhausen, Federal Republic of Germany Förbundsrepubliken Tyskland (DE) (7 * +) Antti Impola (5 * 0 Method for producing polyethylene with a molecular weight above 500 000 - Förfarande för framställning av polyeten med en molekylvikt över 500 000

It is known to polymerize ethylene at pressures of about 100 ° C at temperatures up to about 100 ° C with a catalyst consisting of mixtures of organometallic compounds, in particular aluminum alkyl compounds (and / or aluminum haloalkyl compounds) and periodic (group 4-6 side metal compounds, especially titanium compounds). (cf. Angewandte Chemie, 67, 1955i, pp. 541-547 and Belgian Patents BE 533 362 and BE 534 792.) .

In this method, the molecular weight of the polyethylenes can be varied, for example, by changing the molar ratio between the aluminum alkyl compounds and the titanium compounds, whereby the shift in the direction of the aluminum alkyl compound increases the molecular weight.

The ethylene-containing gas used for the polymerization must go far beyond the group of impurities such as moisture, acetylene, carbon monoxide or sulfur compounds. It has certainly been found that extremely complete removal of oxygen is not advantageous. The addition of small amounts of oxygen, for example 0.005 to 0.05 by volume of ethylene, improves the reaction of ethylene, while the complete removal of oxygen leads to poor yields (German patent publication DE 1 268 847).

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It is known from German patent DE 1 195 4-96 that alcohol can be added during the polymerization of ethylene without oxygen. In this case, the addition of oxygen with the addition of alcohol is adjusted quantitatively so that the addition of oxygen is increased to an amount where the amount of alcohol decreases. By adding alcohol, it is then also possible to adjust the molecular weight of the polyethylene to the desired value, and the higher the amount of alcohol added, the lower the molecular weight of the polyethylene formed.

The presence of alcohol during continuous polymerization on a technical scale is important because it prevents the formation of embarrassing films and fouls in the reactor, so as to avoid clogging of the discharge lines, which in known methods makes polymerization impossible for more than just a few days. On the contrary, the addition of alcohol allows continuous polymerization for several weeks and months without the above-mentioned disturbances and allows the molecular weight to be adjusted so that it can be kept within constant limits.

According to German patent publication DE 1 195 4-96, the aim is preferably to form polymers with viscometrically determined molecular weights of less than about 500,000 to 50,000, it being found that the lower the molecular weight of the polyethylene, the more abundant the film formation. As a result, it was concluded that polyethylenes having molecular weights greater than 500,000 can be produced without interfering with film formation. In the preparation of very high molecular weight polyethylenes using Ziegler's catalysts containing organoaluminum compounds and titanium III halides, it has now been found, quite surprisingly, that by adding alcohol and oxygen for polymerization the presence of the smallest amounts of oxygen leads to If ethylene contains more than 5 parts per million of oxygen, film formation, sintering and grafting occur in both discontinuous and continuous polymerization, so that in most cases it is not possible to carry out the polymerization continuously for more than just a few days. , which allows the preparation of high molecular weight polyethylenes without the addition of alcohol without the above-mentioned adverse effects. The alcohol added during the synthesis is not present as an alcoholate or as a component of the carrier. This is surprisingly possible with the method of the present invention.

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The invention comprises a process for the production of polyethylene having a molecular weight of more than 500,000 at a temperature of 50 to 130 ° C and a pressure of 1 to 100 under normal atmosphere using Ziegler's catalysts containing titanium III halides and organoaluminum compounds.

The invention is characterized in that catalysts containing titanium III halides and organoaluminum compounds in a molar ratio of 1: 0.2 to 1.5 are fed, the titanium III halide being prepared separately to feed ethylene with an oxygen content of less than 5 and that during the polymerization of the reaction mixture, alcohol is added in amounts of 2 to 10 moles per 1 kg of catalyst.

Preferably the molar ratio of titanium III halides to organoaluminum compounds is 1: 0.5 to 1: 1.5 *

The polymerization can be carried out the longer the oxygen-poor ethylene is. The polymerization of ethylene, which has an oxygen content of less than 1 ppm by weight, can be carried out without difficulty for many months without interruption. Mono- or polyhydric aliphatic alcohols having 2 to 5 carbon atoms in the molecule are added to the reaction mixture. The addition of butanol has proven to be very advantageous.

The process according to the invention is expediently carried out in the presence of hydrocarbons having a boiling point of 80 to 200 ° C and suitably purified by hydrogenation before being fed.

The following examples illustrate the invention.

Example 1

For discontinuous ethylene polymerization, a 5 L reactor with a stirrer, gas inlet and outlet line, heat transfer connection, contact initial connection and condenser was used. 2 L of a hydrocarbon fraction boiling at 130-180 ° C, obtained from rock oil and previously purified by hydrogenation with nickel, was poured into the reactor.

The gas used for the polymerization had an ethylene content of 99-95 #, and impurities such as acetylene, carbon monoxide, carbon dioxide, sulfur compounds and water totaled 8 ppm. The oxygen content was less than 1 ppm.

Titanium trichloride used as a catalyst component was prepared as follows:

In a mixing vessel with a volume of about 1 l, 0.5 l of the same gasoline fraction, which was also used for polymerization, 31-6 g of diethylaluminum monochloride and 25.0 g of titanium t etchachloride were placed under type protection. The molar ratio of titanium tetrachloride to diethylaluminum monochloride is 1: 2. The mixture was then suitably stirred for 1 hour at room temperature 58358. The hydrocarbon-insoluble titanium chloride was filtered off and washed several times with a well-purified gasoline fraction. So much gasoline was then added that the original volume was reached again.

To prepare the catalyst used for the polymerization, titanium chloride insoluble in gasoline was added to the suspension with stirring, and then 9 to 5 g of diethylaluminum monochloride was added. The molar ratio of titanium trichloride to diethylaluminum monochloride is 1: 0.6.

The discontinuous polymerization was performed at 80 ° C. 2.0 g of the above catalyst were taken and then 0.8 cm 3 of butanol was added. The ethylene reaction was practically complete after a reaction time of 5 hours. This had resulted in the formation of 685 g of polyethylene having a viscometrically determined molecular weight of about 1,300,000.

Example 2

In the discontinuous polymerization of ethylene, the procedure was as described in Example 1. In contrast, ethylene gas containing 10 parts per million of oxygen was now used. After a reaction time of 5 hours, 569 g of polyethylene having a viscometrically determined molecular weight of 1,100,000 had formed. At the end of the experiment, all pipelines and agitators showed films and adhesions which, as the polymerization continued, resulted in severe polymerization inhibition and arrest.

Example 3

A enamelled and water-jacketed reactor with a volume of about 14 No. was used for the continuous polymerization of ethylene, with a stirrer, a gas inlet and outlet line, a heat transfer connection, a contact initial connection and an outlet line through which part of the reaction mixture was continuously drained. The reactor was charged with 14 ml of a hydrocarbon fraction boiling at 130-180 ° C obtained from rock oil and pre-purified by hydrogenation with nickel.

The ethylene content of the gas used for the polymerization was 99 »95 # · Impurities» such as acetylene, carbon monoxide, carbon dioxide »sulfur compounds and water totaled 8 ppm. The oxygen content was less than 1 ppm.

The spent catalyst was prepared as follows: A reaction vessel having a volume of about 800 lsn was charged with 31 to 6 kg of diethylene aluminum monochloride dissolved in 500 l of the same gasoline-5 58338 fraction, which was also used for polymerization. 25 kg of titanium tetrachloride dissolved in 100 l of petrol were then added over a period of 4 hours with stirring at 20-22 ° C. The molar ratio of titanium tetrachloride to d ± ethylaluminum monochloride is 1: 2. Stirring was then continued for 8 hours at 20-22 ° C and after stirring the catalyst solution was allowed to stand for a further 12 hours. The mother liquor on top of the precipitated titanium trichloride was then carefully wiped off with a spatula and the titanium trichloride was washed twice more with gasoline. The titanium trichloride was then diluted with 500 L of gasoline and pressurized with nitrogen into a about $ 000 L contact storage tank. 9.5 kg of diethylaluminum monochloride was then added and the storage tank was filled with 5,000 l of gasoline. The catalyst mixture contained 10 g of catalyst / l solution. The molar ratio of titanium trichloride to diethylaluminum monochloride is 1: 0.6.

The polymerization was carried out at a temperature of 80 ° C. The catalyst prepared above was continuously fed to a 500 g / h reactor. In addition, react Torun was charged with 100 cnr of butanol per hour. The average amount of ethylene obtained was about 250 m 2 / h. The reaction product was continuously removed from the reactor and divided into polyethylene and auxiliary liquid in an associated filter apparatus. The auxiliary liquid was returned to the polymerization reactor. The polyethylene was released from the gasoline and catalyst residues still trapped in the included ash remover. After drying, a white powder with a viscometrically observed molecular weight of 1,000,000 to 1,200,000 over months was obtained. Also, during several months of operation, no difficulties with the films and deterioration in the reactor were observed.

Claims (3)

58338 A process for the production of polyethylene having a molecular weight of more than 500,000 at temperatures of 30 to 130 ° C and pressures of 1 to 100 under normal atmospheres using Ziegler's catalysts containing titanium III halides and organoaluminum compounds, characterized in that that catalysts containing titanium III halides and organoaluminum compounds in a molar ratio of 1: 0.2 to 1: 5 are prepared, the titanium III halide being prepared separately, that ethylene having an oxygen content of less than 5 ppm is fed, and that polyhydric aliphatic alcohols having 2 to 5 carbon atoms are added to the reaction mixture during the polymerization, alone or as a mixture of two or more alcohols in amounts of 2 to 10 moles per 1 kg of catalyst. Process according to Claim 1, characterized in that the molar ratio between titanium III halides and organoaluminum compounds is 1: 0.5 to 1: 1.5. Process according to Claims 1 and 2, characterized in that the oxygen content of the ethylene is less than 1 ppm.