DE1008488B - Process for removing catalyst residues from polyolefins - Google Patents

Description

The invention relates to a method for removing. Catalyst residues from polyolefins, the polymerization of olefins or olefin mixtures in the presence of organoaluminum compounds as catalysts with or without the addition of metal salts as cocatalysts are, which is characterized in that such polyolefins, preferably in the form of crude reaction product, with aluminum trichloride in an organic inert solvent for aluminum trichloride treated and then extracted with an aliphatic alcohol. It is special Process suitable for cleaning polyethylene.

The processes for producing the polyolefins used as starting material are described in German 878 560, in British patents 713 081 and 742 642, in French Patent specification 1,099,257 and in Belgian patent specification 533,362.

In one of the patents, the use of methanol or methanolic hydrochloric acid for the decomposition and removal of metal compounds.

By the invention; Procedure, on the other hand a more convenient and practically complete removal of residual metal compounds obtained from polyolefins prepared in the manner described above.

It is believed that the removal of catalyst residues is primarily through the reaction the organoaluminum compound with the aluminum trichloride to form a substance (which a compound, a complex or an adduct), which is easily soluble in an aliphatic alcohol is, is effected. Aluminum trialkyls react with aluminum trichloride in a molar ratio 1: 2 with the formation of aluminum mono-alkyl dichloride. The latter substance and aluminum trichloride are soluble in alcohols, while aluminum trialkyls and aluminum dialkyl chlorides are insoluble or only partially soluble in alcohols.

Any organic solvent in which aluminum trichloride is sufficiently soluble without decomposition can be used. Alcohols are therefore not usable as solvents for aluminum trichloride, since they form addition products with this. The preferred solvent is diethyl ether.

According to an advantageous embodiment of the process according to the invention, a solution of aluminum trichloride in diethyl ether is added to the crude reaction product, which contains the polyolefin, the polymerization catalyst and the original solvent, and the whole is stirred for a short time for thorough mixing. Purpose of removal procedure
of catalyst residues from polyolefins

Applicant:
Petrochemicals Limited, London

Representative: Dr. K. Sctiwarzhans, patent attorney,
Munich 38, Romanplatz 9

Claims Priority:
Great Britain December 24th. 1954

Edward Teggin Borrows, Bowdon, Chester,
and Norman Entwistle, Oldham, Lancaster

(Great Britain),
have been named as inventors

Heating can be used to facilitate mixing and shorten the time required. Then it will be an aliphatic alcohol is added to the total amount or to dissolve out the majority of the catalyst residues present. The preferred Alcohols are methyl alcohol and ethyl alcohol.

The amount of aluminum trichloride added is determined by the amount to be removed remaining metal compound or compounds. So much aluminum trichloride should be added, that the ratio of aluminum to halogen in the entire system (expressed in molecular Quantities) is 1: 2. The addition of excess aluminum trihalide is not detrimental as this forms a soluble product with the alcohol; but it is clear that a large excess is avoided shall be.

The invention is advantageously applied to polyolefins with mixed catalysts according to the British patent.

The invention is illustrated by the following examples. In these examples, those given relate to Parts by weight. The starting materials used are polymers as they are essentially obtained after the polymerization reaction according to Example 4 of Belgian patent 533,362 will.

example 1

The starting material was polyethylene, which is isooctane through the polymerization of ethylene in 420 parts

709 509/448

using 3.5 parts of aluminum triethyl and 1.15 parts of titanium tetrachloride as a catalyst (molar ratio of aluminum to titanium 5: 1). After the end of the polymerization, 7 parts of aluminum trichloride in 36 parts of diethyl ether were added and the mixture was stirred at 80.degree. ^{C. for 1 hour.} Then 125 g of methanol was added to the hot mixture and after 13 minutes the polymer was filtered off and washed with methanol.

The ash of the dried polymer was 0.2%, while without the aluminum trichloride treatment, but with a methanol treatment according to Example 4 of Belgian patent 533 362 Polymer with 3.4% ash is obtained.

Example 2

Example 1 was repeated using polyethylene which was polymerized in 420 parts Xylene has been obtained in place of the isooctane. The polymer gave 0.08% ash on incineration, while without the aluminum trichloride treatment, but with methanol treatment, as indicated in Example 1, the polymer gave 1% residue on ashing.

Example 3

It was purified polyethylene, which is by polymerization of ethylene in 400 parts with isooctane 6 parts of aluminum triisobutyl and 1.15 parts of titanium tetrachloride was formed as a catalyst. After finished Polymerization, 7 parts of aluminum trichloride in 36 parts of diethyl ether were added and that Mixture treated as in the previous examples. The obtained polymer contained on ashing 0.3% ash, while a polymer, which without treatment with aluminum trichloride solution with methanolic hydrochloric acid, gave 2.7% residue on ashing.

Example 4

40

The starting material was polyethylene, which is isooctane through the polymerization of ethylene in 420 parts using 40 parts of aluminum diethyl monochloride and 1.15 parts of titanium tetrachloride as Catalyst has been recovered. (The molar ratio of aluminum to titanium was 5.5: 1.) After that finished Polymerization, 1.5 parts of aluminum trichloride in 36 parts of diethyl ether were added and the mixture heated to 100 ° for 1 hour. During this time, part of the diethyl ether evaporated the mixture. While the mixture was still hot, 120 parts of methanol were added, and gradually The polymer was filtered off for 15 minutes and washed with methanol.

The ash of the dried polymer was 0.08% while the polymer without the aluminum trichloride treatment Yielded 0.9% ash.

Example 5

Polyethylene was purified by polymerizing ethylene in 420 parts of petroleum ether (Boiling point 140 to 160 °) using 5.3 parts of aluminum diisobutyl monochloride and 1.15 parts of titanium tetrachloride (aluminum to titanium molar ratio 5: 1) has been prepared. After finished Polymerization, 7 parts of aluminum trichloride in 36 parts of diethyl ether were added and that Mixture stirred at 80 ° for 1 hour. Then 125 parts of methanol were added and the mixture became held at 60 ° for 30 minutes with stirring. The polymer was filtered and washed as in Example 1. The ash of the dried polymer was 0.02%, while the ash content without aluminum trichloride treatment was 0.14%.

Example 6

The starting material was polyethylene, which was obtained by polymerizing. Ethylene in 840 g of isooctane using 3.2 g of aluminum diethyl monochloride and 0.495 g of Ti Cl ₄ has been obtained. The brown reaction product slurry containing a total of 105 g of polymer was divided into 3 portions and these were treated as follows:

a) 1.25 g of AlCl ₃ in 6.25 g of ether were added to the first portion and the suspension was thoroughly stirred at 60 ° for two and a half hours. Then 75 g of methanol were added to the hot mixture, and after a further 10 minutes the polymer was filtered off and washed with methanol. After drying at 60 °, the ash content thereof was 0.05%.

b) 1.25 g of Al Cl ₃ in 6.25 g of ether were added to the second part, and this slurry, too, was thoroughly stirred for two and a half hours at 60 °. Then 75 g of methanol were added to the hot mixture, and then, after a further 10 minutes, the polymer was filtered off and washed with 5% of a NaOH solution and with water and methanol. The polymer filtered off was then dried at 60 ° and showed an ash content of 0.035%.

c) Only 100g of methanol and then 5% were added to the third portion of the slurry Sodium hydroxide solution was added, whereupon the polymer was filtered off and again with water and methanol washed. The ash content of the dried polymer was 0.18%.

Example 7

A dark brown reaction slurry obtained by polymerizing ethylene in 840 g of isooctane using 6.9 g of aluminum triethylene and 2.18 g of Ti Cl ₄ and containing a total of 104 g of polymer was divided into 3 parts and treated as follows:

a) 4.4 g of Al Cl ₃ in 22 g of diethyl ether were added to the first portion and the mixture was stirred at 60 ° for 1/2 hour. 100 g of methanol were then added and the mixture was stirred for a further 10 minutes, after which the polymer was filtered off, washed with further methanol and dried at 60 °. The ash content of the dry powder was 0.23%.

b) 4.4 g of Al Cl ₃ in 22 g of diethyl ether were also added to the second portion and this mixture was stirred thoroughly at 60 ° for 2 hours. Then 100 g of methanol and, after a further 10 minutes, 5% sodium hydroxide solution were added. The polymer was then filtered off, washed with water and methanol, and dried at 60 °. The ash content of the dried polymer was 0.15%.

c) Only 100 g of methanol and then 5% NaOH solution were added to the third portion. The polymer was filtered off, washed with water and methanol, and dried at 60 °. Of the The ash content of the dried polymer was 2.6%.

Claims (5)

PATENT APPLICATIONS: 1. Process for removing catalyst residues from polyolefins by polymerization of olefins or olefin mixtures in the presence of organoaluminum compounds as catalysts have been produced with or without the addition of metal salts as cocatalysts, thereby marked that one. the polyolefins, preferably in the form of the crude reaction product, with aluminum trichloride in an organic inert solvent for aluminum trichloride treated and then extracted with an aliphatic alcohol. 2. The method according to claim 1, characterized in that the aluminum trichloride in such Amount is added. That it is the total amount of the aluminum catalyst residue in aluminum monoalkyl dichloride converts. 3. The method according to claim 2, characterized in that that the amount of added AIu- mimumtrichlorids is so large that it can be used to adjust the ratio of aluminum to Chlorine to 1: 2 (expressed as a molecular amount) is sufficient if trialkyl aluminum is used as the catalyst has been used. 4. The method according to any one of the preceding claims, characterized in that as Solvent for the aluminum trichloride diethyl ether is used. 5. The method according to any one of the preceding claims, characterized in that for Extracting methyl or ethyl alcohol is used. Considered publications:
German Patent No. 878 560;
U.S. Patent No. 2,220,930.