DE2600205A1 - METHOD OF PURIFYING OLEFINE POLYMERS - Google Patents

Description

Process for purifying olefin polymers

The invention relates to a process for purifying olefin polymers obtained by polymerization of one or more olefins with the aid of a catalyst comprising a titanium halide and an organic alurainium compound includes. The crude olefin polymers thus obtained can contain catalyst residues which may have an unfavorable effect on the properties of the polymer. Under "Catalyst residues" are next to the catalyst itself its decomposition products or derivatives, if applicable were formed during the polymerization.

Removal of these catalyst residues becomes common referred to as "deashing", and the efficiency of this process is generally judged by the percentage of titanium removed from the polymer during the cleaning process will. This degree of efficiency is given by the following expression:

_uirkunGScrad

Ash removal = 100

(Ti. = Ti at the beginning of the polymerization, Ti ₁ , = Ti at the end of the polymerization.)

609828/0921

ORIGINAL INSPECTED

This definition is usually chosen because the titanium can be determined more precisely than e.g. the aluminum and, in addition, the amount of other elements withdrawn is practically the same as that of ditan.

The inventive method for purifying olefin polymers, obtained by polymerizing one or more olefins with the aid of a catalyst containing a Titanium halide and an organic aluminum compound is characterized in that one

(a) Contacting a slurry of the polymer in a liquid hydrocarbon medium at 0.01 20 G-ew .- / j (calculated on the liquid phase) one Alcohol and with at least 0.1 Hol oxygen or aD? equivalent Kenge of a peroxide each in the Slurry present G-rammatom Qitan and that one

(b) the polymer with a liquid hydrocarbon oil ο diura in the presence of 0.01-20% by weight (calculated. on the 'washing liquid) of an alcohol washes out.

The detergent olefin polymers can be polymers of Be olefins which have, for example, 2 to 6 carbon atoms, such as ethylene, propylene, 1- or 2-butene, isobutene and 1-hexene. The method according to the invention is particularly suitable for deashing of polypropylene, as described in more detail below will.

Propylene is usually polymerized in the liquid phase, with the help of a trivalent titanium compound, in particular of üiGT ~, and an aluminum dialkyl halide as Activator as described, for example, in British Patents 1,120,079, 1,390, 335 and 1,372,440.

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9 π η η ο η c

/.UUU^UJ

Polymerization is usually carried out "in the presence of a liquid hydrocarbon in which the propylene is practically insoluble, as a diluent. A slurry of solid polypropylene, the catalyst residues and the diluent is formed. Suitable diluents include propane, pentano and Ilexa , the isooctanes and hydrocarbon mixtures, & .P .. "Aviation alkylate". J) The process according to the invention is of particular interest when it is a matter of slurries which, as a liquid hydrocarbon medium, contain an excess of the liquid olefin monomer (propylene ), possibly together with the corresponding saturated hydrocarbon (propane). The concentration of the slurry, i.e. its content of solid polypropylene _v can be 10 to 6_ ^r 3 ^! wt. - / ύ uurl is preferably 25 to 55 and in particular 30 up to 50 wt. - ',;.

The alcohol used in stage (a) can be a saturated aliphatic alcohol with up to 10 carbon atoms, for example a proanol, a butanol, a pentanol or a honanol. Alcohols with 3 or 4 carbon atoms, in particular isopropanol, 1-butanol and 2-butanol, are preferred. The use of 2-butanol has proven to be advantageous in that it avoids corrosion problems in the equipment used for the process. Mixtures of two or more alcohols can also be used.

When the slurry is contacted with the alcohol, the catalyst becomes inactivated and partially solubilized. The contact time is usually at least 2 minutes, preferably 3 to 15 minutes. De :: alcohol is used in an amount of at least 0.01 wt .-; i and preferably at most 7 wt .-? O, for example from 0.1 to 2 and especially from 0.1 to 1.0% by weight, the percentages being calculated on the liquid phase

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according to the invention also brought into contact with oxygen or a peroxide in order to achieve practically complete decomposition and solubilization of the catalyst residues. In general, oxygen is preferably used, although it is advisable to use a mixture of Op and an inert gas, in particular nitrogen. The gas mixture can be 0.1 to 25, preferably 0.3 to 20 YoI. - ','> Op contain; Mixtures of Op and Ii ₂ with 0.5 to 10 YoI .- ^ Op are particularly preferred. The Poroxid preferably has a half-life of a Stunae at a temperature within the range of 50 to 175 preferably from 60 to 140 particularly preferred ⁰ C. A peroxide is dilauroyl peroxide.

The amount of oxygen is expediently 0.1 to 50, preferably 0.2 to 2.5 and in particular 0.25 to 2 mol Op per g atom of Ti. If a peroxide is used, its amount is equivalent to the amount of oxygen mentioned; it is e.g. 0.25 up to 2 Hol dilauroyl peroxide per g-atom of Ti.

If necessary, the polymer can be combined with oxygen and with the alcohol at the same time, but it is preferred to first add the alcohol and only then the oxygen or the peroxide. The mass is expediently stirred vigorously in order to bring about an intimate contact between gas and liquid. However, the Iiontaktzeit can vary within wide limits, in general between 1 and 50 ^a inutes and in particular between 5 and 50 minutes. If a peroxide is used, this can also be added, for example, with the alcohol, either all at once or in portions, for example within a period of 1 to 50 or preferably 5 to 50 minutes.

Since the decomposition of the catalyst can release hydrogen halide, which can lead to signs of corrosion,

609828/0921

It is recommended to use gin scavengers along with the alcohol for the hydrogen halide, preferably propylene oxide, to be added. The scavenger is preferably used in an amount which is 0.5 to 20, in particular 1 to 15 Hol per g-atom of Ti.

The temperature is carrying out step (aj preferably from 20 to 80, in particular at 20 to 6O ⁰ C.

In order to keep the reaction medium liquid, it may be useful to maintain an overpressure, for example when propylene or a mixture of propylene and propane is used as the diluent.

After performing the step ο (, aj, the slurry in the presence of an alcohol with a liquid hydrocarbon washed out what the stage (bj of the process uarstGi.lt.

It lu11 itself air; Proven beneficial to wash out one Hydrocarbon to use, the dom used in Stufo (aj corresponds to, z.] 3. the Olufiumouomer, which optionally the contains a saturated compound, i.e., ProTjylen or a mixture of propylene and propane.

Surprisingly, it has been found that the efficiency during ash removal is increased quite considerably if in the Washing liquid is alcohol auwesoud. The alcohol is preferred of the same type as that in stage (a), i.e. one uses preferably a saturated alcohol with 5 or 4 carbon atoms, e.g. iGopropyl alcohol, 1-butanol or 2-butanol.

The amount of the washing in step (b) alcohol used is preferably not more than 7 wt ^f />, for example from 0.1 to 2 and especially 0.1 to 1.0 wt .- '>, relative / to the washing liquid . The washing out can be carried out at a temperature from 10 to 00, preferably from 50 to 50 ^0C . Preferential

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-G-

Sometimes washing is carried out with stirring. With batch-wise The liquid phase is worked out, e.g. by filtration the slurry is separated and the polymer is then mixed with fresh portions of liquid rOhlenrjstoff and alcohol brought into contact. In general, the desired degree of purity can be achieved with a few, usually two Ash processes. You can also get the slurry through a Column lead, uuroh which the 7 / asohmediurn in countercurrent α ur c hg e 1 e i t e t w i r d.

The in-aungsgomliche procedure is noisy without carry out further batchwise, but it is preferably carried out continuously or semi-continuously Are you working? ; a ng.

The purified polypropylene obtained after separating the liquid phase has excellent mechanical properties; for example, its yield stress is 37 ₉ 5 Ml / τα

example Slurry of polypropylene

The tests were carried out in a 2 1/2 liter stainless steel autoclave with external heating and a stirrer Steel (AIoI;> 16). JTahe the bottom of the autoclave was a "Hoke" filter (40-55 / n) arranged, with the help of which the slurry filtered and the filtrate through an opening in the bottom the autoclave can be sucked off.

The polypropylene slurry was obtained through Polymerization of propylene in the cash register, using a catalyst which had been prepared by reducing [DiOl. with Al (ü., II,) ·, -, as described, for example, in US Pat

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_ π -

G-B-PS 1 390 355} where pentane was used as a diluent.

According to G-B-PS 1,372,440, the polymerization lasted six hours

Lang "was carried out at 60 C and yielded about 3000 g of polypropylene (PP) per g of TiCl ₅ /. 600 g of this', quietly obtained slurry of polypropylene in propylene monomer were placed in the autoclave after this was 15 hours at 90 ^° C flushed with nitrogen and cooled ^{to 20 ° C.}

Decomposition of the catalyst

After the slurry had been diluted to the desired concentration with propylene fed in from a cylinder under nitrogen pressure, it was never heated to 45 ° C. with stirring, whereupon an appropriately dosed mixture of 1-butanol (ROH) and propylene oxide (PO) was pumped into the autoclave . Stirring was continued at the same temperature for a further 15 minutes, after which an oxygen-nitrogen mixture with 0.5 volume percent Op was introduced gradually, ie within 30 minutes. Then, the autoclave was cooled within about 10 minutes at 40 ⁰ C, after which the liquid was abfiltrinrt Destandteile within about 30 seconds.

Extraction (washing)

Was the extraction of the solubilized Katalysatorrückstiüide from the fes'uen polypropylene was carried out by introducing fresh propylene in the held at 40 ⁰ C autoclave within 30 sec., The Propylenraenge corresponded to the stripped propylene and the ^ required uautitat of 1-butanol was pumped simultaneously . The mixture was then stirred for an additional 60 seconds. The washing liquid was then filtered off and the operation repeated. ! laugh - a total of two extraction processes, the remaining propylene was driven off and the cleaned polypropylene removed from the autoclave. .

609828/0921

The propylene was evaporated from the filtrates obtained and the residue worked up to determine the titanium content, which took place with the help of X-ray Pluoreszeuz.

I) aG polypropylene powder obtained in a vacuum oven at 60 to 70 C until the weight icons dance dried, what it was examined for its contents of Ti, Δ1 and Gl with X-ray fluorescence.

The test conditions and the results are shown in the table.

When comparing the experiments 1 and 2, so the sharp rise in the "efficiency of deashing becomes clear when 1-butanol was added to the washing liquid (propylene), while a comparison of Example 'j with eng Examples 4 ·, 5 and 6, the shows astonishing effect of an oxidizing agent in the decomposition stage on the degree of efficiency during ash removal. Both results together show that both measures are necessary if one wants to achieve a good degree of efficiency during ash removal.

Tabel

609828/0921

Tabel

Conc. Ash removal conditions AufBohl. ■

Components of the "ashes"

Effect s gr a el ^ϋ · Ash removal

-before. Ash removal! after ash removal

solid
PP in
On sc hl.
Gev /.^/ ό RAW in
flow.
phase Yerh. Yerh. Introductory
0 ₉ / Ti PO / Ti time fO ₉
(Hol / (Hol / (rain)
G-At) g-At) approx 3 30th RAW
in d.
flow.
phase Ti
ν ppm Al Cl
pp ppm Ti
ppra Al
ppm Cl deprived
Ti in -S 1 34.3 0.44 0.43 approx 8 30th 0.5 90 293 "- 5 28 63 94 2 31.5 0.42 0.49 approx 9 - 0 90 293 - 31 47 72 ■ 66 3 39.4 1 .3 0 approx 9 15th approx 1 137 567 - 34 17th 160 39 4th 44.8 1.2 0.36 approx 16 30th approx 1 129 336 - 16 33 55 88 VJl 24.9 1.0 1.1 ^a ) approx 10 15 °) approx 1 100 190 - 8th .19 50 92 6th 32.6 1.0 o.o °) 1 113 316 - 9 20th 18th 92

a) The mixture of O _{2 and} ITg contained 5 YoI.-Ja Og.

ti) Instead of O v / a 5-S-ice solution you uilauroyl peroxide (DLP) in isooctane was used;

IVi ¹ I = 0.3 Hol per G-Atera. c) Contact time τπΐΐ DLJ ?.

PatennansOrücho

Claims (10)

a t e η t a η s rr r ü c h e Process for purifying olefin polymers obtained were made by polymerizing one or more olefins using a. Titanium halide and a catalyst organic aluminum compound, characterized that he (a) contacting a slurry of the polymer in a liquid hydrocarbon medium at 0.0.1 to 20 wt .-, ο (calculated on the liquid phase) one Alcohol and with at least 0.1 hol oxygen or an equivalent length of period, per g-atom in the Slurry titanium present and that one (b) the polymer with a liquid hydrocarbon medium washes out in the presence of 0.1 to 20 wt .- / * (calculated on the washing liquid) of an alcohol. 2. The method according to claim 1, characterized in that g e Ic e η η, that the polymer is polypropylene. 3. The method according to claim 1 or 2, characterized g e k e η η draw t that the liquid olefin monomer itself is used as the liquid hydrocarbon medium in step (a) or (b), possibly saturated with the onliDprcciieiiueu Hydrocarbons like together. 4. The method according to eiuem of claims 1 to 3, characterized g e k e η>. ζ e i c h η c t that the alcohol in stage (a) or (b) a saturated alcohol having 3 or 4 carbon atoms used. 609828/0921 5. The method according to any one of claims 1 to 4, characterized in that in step (a) or (b) the alcohol in an amount of not more than 7 G-evi.-jS,
calculated on the liquid phase, v / ends. 6. The method according to any one of claims 1 to 5, characterized geke η η ζ eich η et that the oxygen is used in a mixture with an inert gas. 7. The method according to any one of claims 1 to 6, • characterized in that the slurry is first in contact with the alcohol and then with the oxygen brings. ■ * o 8. The method according to any one of claims 1 to b, characterized characterized in that the peroxide used is bilauroyl peroxide verv / ends. 9. The method according to any one of claims 1 to 8, characterized in that step (a) in
Carries out the presence of a trap for the hydrogen halide formed. 10. Ancestors according to any one of claims 1 to 9 »thereby geke η 'η ζ η et calibration, which comprises carrying out the step (a) at 20 to 8O ⁰ C and step (b) at 30 to 50 ⁰ C. 8682 609828/0921