DE2314412A1 - PROCESS FOR POLYMERIZING OLEFINS - Google Patents

Description

"Process for polymerizing olefins

The invention relates to the polymerization of olefins using a catalyst system, which with a AliuainiuEialkyl has been activated. The preferred catalyst system contains chromium t3: io>: id on a carrier material together with a reduced transition metal compound, activated with aluminum alkyl; but it is also chromium trioxide alone, activated with a suitable aluminum trialkyl, for example. wise aluminum trioctyl for certain olefin polymerizations

suitable.

The invention further relates to the manufactured Polymers including fibrous polymers. In this Form, the polymer is ideally suited for the production of synthetic paper.

Accordingly, the invention features a process for making an olefin polymer - wherein in the specification

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"Polymer" is used in the broadest sense and thus also includes copolymers, in which the olefin monomer is brought into contact with a catalyst system which consists of chromium trioxide, activated with an aluminum alkyl, on a carrier material. The chromium trioxide can be used alone; but it is preferably 'a ■' Übergangsmetallverbiadung reduced, for example reduced with an organomagnesium compound in admixture with Titantetrahäbgenid and activated with aluminum alkyl such as an aluminum trialkyl, Aluminiumdialkylhalogenid · or a combination of both used.

The chromium trioxide is used in conjunction with a carrier material; The preferred carrier material is a silicon-containing material, for example silica (silica, SiOp) or an alumosilicate. The carrier-containing chromium trioxide catalyst is expediently prepared as follows: CrO is dissolved in the water, namely in the amount of Cr in the activated catalyst for the desired Cr content necessary amount and wherein the amount of water is just sufficient to be completely absorbed by the wearer. The aqueous Cro ^ solution is then mixed with the carrier material and heated, with stirring, reaching 150 ⁰ C to the temperature. It, the whole is placed in a column for swirling and dryer in a stream of air for 5 hours at the desired activation temperature, for example 350 to 1000 ⁰ C, preferably heated 450 to 75O ° C. The air flow rate is 20 volumes of air / volume of catalyst beads / h. The activated catalyst is then cooled in dry air, the air is displaced by dry nitrogen and the catalyst is stored either as a solid or as a slurry in isooctane.

The combination of carrier-chromium trioxide is expedient activated with an aluminum alkyl, preferably with one

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Aluminum trialkyl containing 4 to 12 carbon atoms, in particular Contains 8 to 12 carbon atoms in the alkyl group; are suitable but also aluminum dialkyl halides or mixtures of aluminum trialkyl and aluminum dialkyl halide.

The olefin polymerization using the carrier-containing Chromium trioxide catalyst in the absence of a cocatalyst is usually carried out at temperatures above 100 ° G; aluminum alkyls are used as cocatalysts, the polymerization proceeds well at temperatures below T 100 ° 0 and at lower pressures. Hydrogen, which is generally very effective in the molecular weight distribution of the polymer when used controls by Ziegler catalysts is in the presence the supported chromium trioxide catalyst is not as effective, however, the molecular weight distribution can be adequately controlled when a transition metal halide is in a, lower Valence level used together with the chromium trioxide system will.

The combination of carrier, chromium trioxide and aluminum trialkyl activator leads to polymers with a very broad molecular weight distribution, while transition metal halides activated in the same way lead in a lower valence level to a narrow molecular weight distribution in the polymer. Purely certain For product applications, it is advantageous to set the molecular weight distribution within these wide limits to be able to. This is possible with the catalyst system provided according to the invention by increasing the ratio of chromium trioxide to transition metal halide is adjusted accordingly.

Any transition metal compounds or mixtures thereof that can be reduced from their maximum valency, for example using an organoaluminum or organomagnesium compound and in the presence of an ac-

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tivators as catalysts for the polymerization of olefins can act as a mixture with the combination of carrier material "and chromium trioxide for carrying out the invention Procedure are used. Suitable transition metal compounds are the halides of titanium, vanadium, chromium, molybdenum and zircon. A particularly suitable Ziegler catalyst is obtained by titanium tetrachloride is reduced to a catalyst consisting entirely or predominantly of titanium trichloride. Accordingly, the method of the present invention is described below with particular reference to this type of catalyst system; However, the claimed method does not apply to these Systems limited but generally applicable to the manufacture of all types of reduced Ziegler catalysts.

The actual polymerization can be carried out in accordance with the usual procedures in customary Ziegler polymerization processes be performed. Generally, the catalyst or catalyst components are in a hydrocarbon solvent introduced into a polymerization kettle, in which then the monomer or monomer mixture, if a copolymer is desired The polymerization is carried out under a suitable pressure: at atmospheric pressure, the Yield, while at high pressures the device cost increases very high. Accordingly, the polymerization in Presence of the intended catalyst activator system at superatmospheric pressure, preferably below 100 bar and expediently carried out at about 2 to 15 bar.

In the polymerization of olefins with a Ziegler catalyst, the use of a fluidized bed system is in the absence aimed at by solvent. However, until now, Ziegler-type catalysts have generally not had a sufficiently high activity Developed to make working in the fluidized bed practicable, as the end product contained too much catalyst residues,

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difficult to remove. In contrast, the Ziegler chromium trioxide catalysts provided according to the invention are due to their high activity potentially suitable for gas phase polymerizations. The activators provided according to the invention can be used advantageously in such methods.

The process according to the invention is particularly suitable for the polymerization of ethylene or the copolymerization of ethylene with other polymerizable 1-olefin monomers, for example propylene. The invention therefore also encompasses the catalyst suitable for olefin polymerization itself as well as a method of producing such a catalyst.

The on a process for the production of olefin polymers directed invention also includes the olefin polymers prepared in the manner described, especially polyethylene, polypropylene and copolymers of ethylene and propylene and molded products made from these polymers.

An advantage of the method according to the invention is that that the polyolefins produced then do not have to be deashed. For this reason, inter alia, that is according to the invention intended catalyst system ideally suited for the production of polyolefin fibers directly in the reactor; the fibers are suitable is used to a large extent in the manufacture of synthetic paper. Different approaches are used in other proposals for the production of synthetic paper described.

The invention is further illustrated by the following examples explained.

example 1

a) Production of the chromium catalyst containing the carrier material 0.384-8 g of CrO- were ionized in 33.76 cm ^ deionized water

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• (SiO ₂ )

dissolved and added 8 g of silica /. The mixture was slowly heated on a hot plate while gently stirring until 'to 150 ^0th The whole thing was then placed in a vertical reactor tube and swirled there with a stream of dry air and at the same time heated to a temperature of 550 ° C. The air flow rate was 20 l / h and the heating time was 5 h. It was then cooled to room temperature while dry air was passed through at the same time; then, the air was displaced with dry nitrogen. The activated catalyst was discharged from the reactor under nitrogen and divided into two parts:

Part A was made as a dry powder under dry nitrogen kept. .

Part B was slurried in dry isooctane; the slurry contained 30 ml / l CrO ^ and was dried under dry conditions Stored nitrogen.

b) Polymerization ■ ■

1.5 l of dry isooctane was fed into a 2 l stainless steel autoclave and the air was displaced by purging with nitrogen. 3 mmol of aluminum alkyl were then added in the form of a molar solution in isooctane. The reactor temperature was increased to 90 ° C. and 0.075 mmol of CrO ₅ , in the form of slurry B in isooctane, was added. The nitrogen was displaced by a gas mixture that contained 40% by volume of ethylene and 60% by volume of hydrogen. The reactor was closed airtight, the pressure was increased to 7.9 bar by means of the ethylene-hydrogen mixture and the gas mixture was fed in at a constant rate of 300A / h for 3 hours. At the same time, gas was continuously blown off in order to keep the pressure at 7 * 9 bar. After 3 h, the pressure was released and the reactor contents were discharged.

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The results obtained with three different aluminum alkyls are summarized in the table below and explain the advantages of using a long-chain Aluminum alkyl as cocatalyst "are effected.

c) In another series of polymerizations in the same
The reactor temperature was reduced ^{to 80 ° C. in the autoclave}
and the composition of the gas mixture fed in in 50
Vol .-% ethylene and 50 vol .-% hydrogen changed. Otherwise, the conditions described above were complied with. The results obtained with aluminum triisobutyl, aluminum trioctyl and aluminum tritetradecyl as cocatalysts are shown in FIG
Table 2 below. They show the further advantage in terms of activity when an alkyl with more than 8 carbon atoms is used.

As a measure of the molecular weight distribution, it was found that the logarithm of the ratio of polymer melt index under a load of 21.6 kg to polymer melt index under a load of 2.16 kg ("flow parameter") is related to Mw / Mn = Q (Mw = MW weight average, Mn = MW number average). Flow parameters above 2.2 thus correspond to Q values above 730;
Flow parameters of about 2.0 correspond to Q values of about 15; Flow parameters of around 1.8 correspond to Q values of around 10
and flow parameters of 1.6 correspond to "Q values of 5 to 6. ^

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TABEL

polymer

Co-Kataly- Yield Melt Index Flow Parameter- Density Sator (Kg ^ g ^- ICrO _x ) (dg mih ~ 1) ter. (G

2.8 0.21

0.17 2.40 0.960

Polymer test not possible

2.16 kg load)

TABLE 2

yield
(Kg.g ~ 1CrO _x ) polymer I. Flow parameters—
ter Co-catalysis
s at or y 2.3
8.5
17.0 *
Melt index
(.ag mm '; 2.56
2 43
2 43 Al (is0-C ₄ Hg) _: 0.06
0.05
0.08

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The very broad molecular weight distribution of the polymers obtained is indicated by the high flow parameters.

example

a) Production of TiCl, catalysts

A titanium trichloride catalyst was prepared as follows: A molar solution of Al (CpHc) Cl in iso-octane was cooled to -30 ° C. and stirred well in a reactor under nitrogen. An equimolar amount of titanium tetrachloride, also dissolved in isooctane, was slowly added. The temperature was kept at -30 ° C. by controlling the feed rate. After the addition was complete, the mixture was warmed to room temperature with constant stirring and then to 160 ° C. under nitrogen pressure in order to convert the TiCl formed from the β form into the purple ~ f ~ form. The catalyst slurry was washed with isooctane to remove aluminum ethyl dichloride.

b) polymerization

The polymerization process according to Example 1b was carried out with the following modifications:

0.15 mmoles of CrO ^ catalyst B and 0.15 mmoles of TiCl ^ catalyst 2 a) were added; * -

the polymerization ^{temperature was 80 °} C .;

the volume ratio of hydrogen to ethylene was 50:

The polymer obtained had the following properties:

Yield = 3.5 kg / g (TiCl, + CrO,),

Melt index = 0.04 dg / min.

The flow parameter was 2.10. Became TiCl ^ catalyst alone used, a polymer with a flow parameter of

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Example 5 '·'

a) Preparation of a TiCl, catalyst

A one molar solution of TiCl. in isooctane was reduced ^{at 30 °} C. with a molar solution of butyl magnesium chloride monobutyl etherate in isooctane. The catalyst slurry was settled five times and the catalyst reslurried in dry isooctane.

b) polymerization

The procedure described in Example 1b) was followed the following amendments applied:

0.075 mmol CrO ₅ -Eat alys at or B and 0.00-5 mmol TiCl, -Catalyst 3 a) were added; .

the polymerization temperature was 80 ° C;

the volume ratio of hydrogen to ethylene was 50:50.

The polymer obtained had the following properties:

Yield = 9.8 kg / g (CrO, + TiCl ₅ );
Melt index = 0.46 dg / min;
Density = 0.962 P

The flow parameter was 1.91. When using TiCl, catalyst all of them gave a polymer with a flow parameter of 1.65.

Two similar polymerizations, carried out without TiCl, catalyst and with a volume ratio of ethylene to hydrogen of 40:60 and 60:40, respectively, gave polymers with a significantly lower melt index of 0.07 and 0.01 dg / min, respectively.

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Example 4

Copolymerization of ethylene and propylene

The procedure was as in Example 1b) with the following modifications :

0.075 mmole CrO ^ catalyst B and 0.00375 mmole TiClj catalyst 3 a) were added;

the polymerization temperature was 80 ° C;

the composition of the gas mixture fed in was:

Ethylene 48 vol .-%
Propylene 2% by volume
Hydrogen 50% by volume.

The copolymer obtained had the following properties:

Yield = 7.3 kg / g (TiCl ₅ + CrO ₅ ); Melt index = 0.42 dg / min;
Density = 0.954 g / cm ⁵ ;
Flow parameter = 2.10.

Example 5

Polymerization to form fibers.

In the 2 1 stainless steel autoclave, 1.3 1 Pure dry isooctane presented and the air displaced by pure dry nitrogen.

The reactor temperature was increased to 90 ° C. and 3 * 0 mmol of aluminum trioctyl and then 0.075 mmol of CrO ₅ in the form of the support material-containing catalyst A suspended in 200 cnr dry isooctane were added. The nitrogen was

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displaced by ethylene and the pressure increased to 7.9 bar. The reactor ^{temperature was increased to 120 °} C. and ethylene was passed in to maintain the pressure. After three hours of polymerisation, the ethylene was displaced with nitrogen and the reactor contents cooled with stirring slowly over a period of 80 min to 4-0 ⁰ C.

The polymer was obtained in fibrous form and could be synthetic Paper to be processed.

Claims

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Claims (1)

Claims 1. Process for polymerizing olefins "in the presence of a catalyst system dadurcli, that chromium trioxide, activated with an aluminum alkyl, applied to a support material is used as a catalyst. 2. The method according to claim 1, characterized in that the catalyst is also a reduced transition metal compound contains. 5. The method according to claim 2, characterized in that one is used as a reduced transition metal compound Titanium tetrahalide reduced with an organomagnesium compound is used. 4. The method according to claim Λ to 3, characterized in that an aluminum trialkyl and / or an aluminum dialkyl halide is used as the aluminum alkyl. 5. The method according to claim 1 to 4, characterized in that there is a silicon-containing carrier material Material used. 6. The method according to claim 1 to 5 »characterized in that the carrier material used is silica . 7. The method according to claim Λ to 5, characterized in that an aluminosilicate is used as the carrier material. 30 9839/1155 -2- 42 659 8. The method according to claim 2 to 7 »characterized in that as with an organomagnesium compound reduced titanium tetrahalide, titanium trichloride used. 9. The method according to claim 1 to 8, characterized in that polyethylene, polypropylene and ethylene-propylene copolymers manufactures. - ... 10. Use of the polyolefin fibers produced according to claims 1 to 9 for the production of synthetic paper. 309839/1155