DE1495278C - Process for working up low-pressure polyolefin dispersions - Google Patents

Description

3 4

hydrogen phase, and the running rotor-stator or rotor-anti-rotor principle work,

Wash solution contains 25 to 90% methanol. z. B. pin mills or disk mills; you are

The new work-up process is known as Disper under the name Ultra-Turrax, Kotthoff mixtures of polyethylene and polypropylene and siren or Supraton mill. An additional dispersions of copolymers, for example 5 advantage when using the disintegrators mentioned from ethylene and propylene, ethylene and a-butylene, is that with otherwise the same equipment in which the proportion of propylene or butylene 0.1 to expenditure the amount of dispersion passed is more than 10 percent by weight, accessible. As a dispersant can be doubled without increasing the sion medium, the usually used carbon ash values in the end product occur,
ο The purified, practically methanol and water-aromatic hydrocarbons. The methanol-free polymer dispersion is then treated in a treatment of the dispersion, for example in a stirrer-suitable separating device, ζ. Β. a centrifuge, take place in kettles and preferably run separately in continuous solids and dispersants. According to the natural mode of operation. Drying gives polymers with an ash content

After the methanol treatment, the mixture is 15 th of less than 0.01% and chlorine contents of

to temperatures below 40 ° C., preferably to 20 to 0.001 to 0.005 ¹⁰ zo. The hydrocarbon filtrate is

30 ° C, cooled and placed in a suitable device, holds when using methanol as a washing

for example a separating bottle, transferred. In the solution in addition to small amounts of wax ingredients only

Separating bottle separates the alcoholic phase, less than 0.006 ¹⁰ Ia methanol. Therefore, the

which is now the bulk of the decomposed mixed hydrocarbon after a simple distillation

contains catalyst, use of the hydrocarbon again.

Phase. From the products processed according to the invention, the solubility of the methanol in the co-dispersions is obtained from the reaction products which are additionally greatly reduced, so that they can be processed in this stage as early as 80 to without causing corrosion 90%> of the catalyst residues 25 and have good electrical properties,
be separated. If desired, you can do that. .
Mixture 0 to 30%, preferably 10 to 25%> What- Example J
Add water, based on the polymer dispersion, to a reactor equipped with a stirrer and cooling system in order to continue the separation and phase separation, and 2,000 per hour are continuously perfected. 30 parts by weight of hexane and a catalyst mixture

The hydrocarbon phase is then introduced in 2.4 parts of dichloro-di-n-propoxytitanate and 25 Ge countercurrent, advantageously continuously, at parts by weight of aluminum sesquichloride,
Doors below 40 ° C, preferably at 20 to 30 ° C, with At the same time, 500 parts by weight of water or methanol-water mixtures are washed every hour. Ethylene initiated. The resulting poly-water-methanol mixtures are particularly effective and ethylene dispersion is continuously withdrawn while maintaining the 25 to 90, preferably 40 to 75,% degree of methanol and in one content. It has proven to be particularly advantageous to add 100 parts by weight of the hydrocarbon phase to the downstream stirred tank per hour, first of all with methanol by weight, continuously pure methanol at 80 to 90 ° C., and to add this mixture. After an average dwell time of 30 mixing holes, expediently in countercurrent, with 40 slots of water, the suspension is washed in a downstream. Here, too, the washing solution running off should be cooled to 20 to 35 ° C. and passed into a 25 to 90, preferably 40 to 75% alcohol separating bottle, in which the alcoholic one is kept. The total amount of washing solution in the phase from the hydrocarbon-polyethylene disperser is usually 10 to 40, preferably 10 to 20%, separately. To increase the specific drawn on the hydrocarbon phase. 45 weight of the alcoholic phase and to reduce

It has also proven to be particularly advantageous if the solubility of the alcohol in the hydrocarbon of the polymer dispersion prior to the countercurrent washing is supplemented by 400 parts by weight of water after adding small amounts of suitable washing. The aqueous-alcoholic phase is withdrawn from continuous solutions with a crushing action of shear and vibration at the bottom of the separating vessel, to be exposed to centrifugal forces. As washing solutions, the hydrocarbon-polyethylene dispersion amounts of about 1 to 20, preferably 5 to 10%, in the upper part after the addition of 750 parts by weight based on the polymer dispersion, methanol is applied through an overflow into a downstream, water and methanol are suitable. This countercurrent washer is running and alkaline agents such as water at 25 ° C can also be washed here with 750 Ge washing solutions. The alkali hydroxide with glycidyl ether or acetylene polyethylene is contained in a centrifuge dissolved from the disperalcohols. Sioning agent is particularly advantageous separately and dried. It takes hours to add the pure Hch 490 parts by weight of a white powder with methanol before the disintegration of the dispersion and after treatment in an ignition residue below 0.1% and a chlorine disintegrator in the countercurrent wash with water content of 0.005%.
to wash. - The shear and vibration forces 60. .
are able to homogenize the dispersions, example
by dividing agglomerates into the individual dispersion particles and bringing about an intimate contact of the 4,000 parts by weight of hexane, 4.75 parts by weight of the detergent every hour with the catalyst residues. Because parts by weight of dichloro-di-n-propoxytitanate and 5 parts by weight, they also ensure the removal of 65 parts by weight of aluminum sesquichloride with 1000 possibly trapped catalyst residues. major ethylene implemented. The dispersion will

The shear and vibration forces can be continuously subtracted and kept at 80 to 90 ° C

caused by disintegrators who after. stirred the 200 parts by weight of methanol. After 30 minutes

After the residence time, the suspension is cooled to 20 to 35 ° C. and mixed with 800 parts by weight of water and in a separating bottle into an aqueous alcoholic and a dispersed polyethylene containing hydrocarbon phase separated. The dispersion that runs off the top of the separating bottle becomes mixed with 1500 parts by weight of methanol and runs through a so-called Kotthoff siren. The middle The residence time of the dispersion in the Kotthoff siren is about one minute. The dispersion is then displayed in a countercurrent washer, which is charged with 1500 parts by weight of water every hour. The centrifuged and dried polyethylene falls in an amount νου, 980 parts by weight per hour and contains an Glührüekstand below 0.01% and a chlorine content of. 0.005%.

Claims (2)

1 2 claims: ", E * hJ has been proposed with normal Ziegler catalysts with polyethylene 1. Process for working up lower alcohols and subsequently with acetone Printing polyolefin dispersions, produced with washing. This process is not very economical Mixed catalysts made from halogen orthotitanic acid 5 and required for the modified ester catalysts 'Esters and organoaluminum compounds, complex alcohols with three or more carbon through Decomposition of the dispersions with an aico-atom, in order to achieve low-ash polymers, fetch at a temperature of up to 90 ° C and continuously. You can also use anhydrous if necessary thorough washing, thereby identifying low-pressure polyolefins with pre-cleaned alcohols draws that the alcohol used is 0.1 to l () per cent. solutions of alkaline substances and of epoxy treat the dispersant, methyl alcohol compounds or acetylene alcohols, used, the mixture cools below 40 ° C, it is still from the German Auslegeschrift if desired up to 30Vo, based on the poly 1,028,319 known, polyethylene dispersions with 0.5 merisate dispersion, adding water, decomposing the alcohol to 5% of an alcohol and then Separate the table phase in a separating vessel and wash it with water and alkaline media. the The dispersions should be both in the dispersant and alcohols either first mixed with methanol and ^[n of the aqueous phase to be sufficiently soluble. Alkodann with water ^{hole 'which we} 8 ^{s at} low hydrocarbon or with a 25 to 90 »Ar methanol corresponds solubility are ^inrer not readily usable, verwendhaltenden methanol-water mixture is ^{30 bar} _T'. ^m _u ^d , ^em " ¹ ^ ¹⁶ working temperature and thus the Solubility increased. This procedure has the washes out in countercurrent, with the total part that the solubilizer, despite the excess amount of the washing solution 10 to 40%, based on the times of washing stubbornly in the hydrocarbon on the hydrocarbon phase, and which tends to hold, entrains catalyst residues and in draining washing solution 25 to 90% methanol 25 unfavorably in the hydrocarbon, i.e. in contains. of the phase containing the polyolefin. 2. The method according to claim 1, characterized in that the required number of washing processes is obtained indicates that the pre-cleaned suspension is made with a large amount of water and a little alcohol sion contains comminuted in the presence of washing solutions and is very expensive to work up. shear and vibration forces 30 also exposed to the addition of wetting and emulsifying agents. teln was suggested (German Auslegeschrift 1,091,333); it is obvious that this leads to one creates the same difficulties. These procedures bring so because of the relatively large lo-35 The possibility of the alcohols in the dispersant does not have adequate ash values, especially when using the It is known to use polyolefins, in particular poly-titanic acid ester mixed catalysts, ethylene and its copolymers, by low A satisfactory removal of the residues from the Pressure polymerization of the corresponding mono-modified mixed catalysts has hitherto been possible With the help of mixed catalysts, reduce the low saponification rate of the ble heavy metal compounds, in particular titanium halogen orthotitanic acid ester only by time-consuming tetrachloride, and organometallic compounds, operations, such as separation of the decomposing alcohol Aluminum alkyl halides, suspension to be produced, subsequent mashing, len. However, these catalysts give polymers, re-separation, etc., can be achieved. For wermit very broad molecular weight distribution, which in 43 den but expensive separation apparatus and large Their mechanical properties are the ones required for many amounts of alcohol, making this process Turning areas today required values are not economically hardly sustainable. always be fair. It has therefore been found that low-pressure poly- beat, as catalyst components halogen-ortho-olefin dispersions, prepared with mixed catalyst titanic acid ester and organoaluminum compounds of haloorthotitanic acid esters and alumines to use, the titanium half esters either organonium compounds, by decomposing the by partial esterification of the titanium tetrachloride with dispersions with an alcohol at a Temperadem Desired alcohol (ethanol, n- and i-propa door up to 90 ° C and continuous washing out nol, isobutanol) or by mixing the titanium tetra in a particularly advantageous manner to polyolefins with Process the chloride with the corresponding titanium tetraester. 55 excellent ash and chlorine values can be asked. Which can be produced in this way if the alcohol is 0.1 to 10% The polymers used in their structure are very much based on the dispersant, methyl alcohol, linear, have a narrow molecular weight distribution, the mixture cools below 40 ° C; if desired and are characterized by good mechanical intrinsic up to 30%>, based on the polymer dispersion, develop. 60 water added, the alcoholic phase in one The polymerizations are usually separated off in a continuous separation vessel and the dispersions are nuier or discontinuously under air and. either _{first mixes with methanol and} Exclusion of moisture in indifferent solvents. _t water like hydrocarbons. ⁿ . _{Contain a 25 to 9Q0 / o MathanQl} . The resulting in finely divided form polymer 6 ₅ methanol-water mixture must be freed from adhering or trapped catalyst residues and washed out of solvent and in countercurrent, the total amount Wash liquid are separated. of the washing solution 10 to 40%, based on the Koh-