DE2225690A1 - Process for the polymerization of propylene - Google Patents

Description

concerning
Process for the polymerization of propylene

The invention relates to a method for polymerizing Propylene in a liquid diluent in the presence of a catalyst system containing titanium trichloride and an aluminum dialkyl halide.

In this description, isotaktisohem polypropylene is meant a polypropylene in boiling ether (34.6 G) is not more than 5 wt .- ^ ₁ preferably no more be i, dissolved than 2 wt .-?. In the polymerization process of the present invention, a number of factors affect the isotacticity of the resulting polypropylene, such as the polymerization temperature and the catalyst system. A higher polymerisation temperature leads to an increase in ataktie. For this reason, temperatures of. more than 90 C generally avoided.

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A high polypropylene yield of e.g. more than 300 g / g TiCl, can lead to a product that does not have to be deashed any further. However, the method according to the invention is not based on the Production of such polypropylenes is limited.

A high yield can be obtained, for example, by using a suitable catalyst system and extreme conditions, such as a high polymerization temperature and a high propylene pressure. A very active catalyst system, which also leads to polypropylene with good isotacticity, is one in which TiGl is added to trialkylaluminum at low temperature, namely below -3O ⁰ C, for example at -7O ⁰ C, and the mixture is then added is heated to over 80 C. The resulting T-TiCl., Is activated with a dialkyl aluminum halide before the polymerization. If this catalyst system is used under extreme polymerization conditions, for example at 75 ° C. and a propylene pressure of 5 bar above atmospheric pressure, it has been found that the bulk density and the isotacticity of the polymer are substantially reduced. This is due to a change in the structure of the TiCl., Particles as a result of an excessively high rate of polymerization at the moment when a fresh catalyst particle comes into contact with the monomer under extreme conditions.

If less active catalyst systems are used, the disadvantages indicated above only become apparent when even more extreme polymerization conditions are used. For example, if T-TiCl., Is produced by treating TiCl, with (C ₀ IL-) _? AlCl is activated under certain conditions at a temperature of eg -30 ⁰ C and subsequent heating to eg 100 to 200 ⁰ C and then with (C ₂ IL) ₂ AlCl ₂ , a catalyst system for propylene polymerization which has certain advantages, but is less active than the one described above. The disadvantage of a reduction in isotacty and bulk density ^{only occurs with this "-30 0} C" system if

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even more extreme polymerization conditions are used, such as at a propylene pressure of 5 bar and a temperature of

80 ⁰ G.

The effect of extreme polymerization conditions can be seen in the table below. The catalyst component was prepared by adding Ä TIGL to (CpH ₁ -), Al at -70 ⁰ C. in a Kolverhältnis of 3: 1.15 and the product was then heated to 155 0 gradually. The catalyst component B was prepared by adding TiCl. to (CpH ^) ₂ AlCl at -3O ⁰ C in a molar ratio of 4: 3 and the product is then gradually heated to 1 55 C. The. resulting ι? -TiCl, -catalyst components A and B were activated with (CpHr-) pAlCl in a Mo Iv ratio of 1: 4 and used for the propylene polymerization. The polymerization time was 4 hours, the temperature was 70 ° C., the propylene pressure was 5 bar and the concentrations of TiCl and (CpHr-) pAlCl were 1 and 4 mmol / l of diluent (alkylated gasoline). The conditions used during the addition of the catalyst system were varied (Table A). Immediately after the addition, the conditions were brought to the values given above, namely to 70 ^° C. and an excess propylene pressure of 5 bar. The following results were obtained.

Table A.

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Table A.

Catalytic nominal catalytic converter component activity (g / g TiGlh -bar) , 4)

A 56

22nd

conditions while (bar) Polypropylene ether the addition of catalyst 5 Schütt soluble 5 density (Weight ~ fo) 5 (g / cm ⁵ ) 1.9 Temperature overpressure 2 0.38 3.4 door ( ⁰ G) 5 0.30 4.6 65 5 0.10 4.0 70 5 0.17 3.8 75 0.36 3.7 75 0.35 4.5 70 0.32 75 80

+) Measured under standard conditions: at 70 ⁰ G, a propylene ^ pressure of 3 bar (absolute) TiCl, and (C ^ EL ^ AICI, concentrations of 3 and 6 mmol / l, 0.75 $ H _? Gas, Polymerization time 4h.

A process has now been developed in order to reduce or avoid the disadvantages which occur when extreme polymerisation conditions are used. The invention relates to a process for the polymerization of propylene in a liquid diluent at a temperature of 62 to 9O ⁰ G and a propylene partial pressure of at least 2 bar (absolute), wherein a catalyst system is added at this temperature, the TIGL _0, and contains a dialkylaluminum and which has previously been brought together with sufficient propylene in a liquid diluent at a temperature below 62 ^° C. so that at least 0.1 g, preferably 0.5 to 5 g of polymer / g of TiCl- could form in the system processes are known in which a catalyst system based on TiCl., and diethylaluminum chloride with a small amount of propylene is brought at a temperature above 60 ⁰ C in contact. The catalyst treated in this way was then used for the polymerization at a temperature below 60 G. In this way, a catalyst and a polymer with a very small particle size are obtained. It is believed that the

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.j. ■

Catalyst parts disintegrate under the conditions mentioned, what is avoided according to the invention. For this "known process However, the conclusion could not be drawn that the prepolymerization according to the invention "at temperatures below 62 C leads to a catalyst system which, under extreme polymerisation conditions does not lead to a loss of bulk density and isotacty.

The process according to the invention is particularly suitable for producing a propylene homopolymer. However, copolymers of propylene with other oC-alkenes, such as ethylene, butene-1 and pentene-1, can advantageously be produced by the process according to the invention. In this I'alle is usually not used more than 1 times the other aC alkene per mole of propylene in the feedstock. The process according to the invention leads at most to minor advantages in the homopolymerization of ethylene.

In principle, any catalyst system can be used which as such has a nominal activity during the first 4 h under standard conditions of at least 10 g, preferably at least 30 g polymer / g TiCl., And h and bar propylene. A number of these systems have already been described above. “Under 'standard conditions” means without the pretreatment according to the invention at a polymerization temperature of 70 ° C. and a propylene pressure of 3 bar (absolute) in the presence of oxygen in isooctane at a
(C ₀ H ^) ₀ AlCl of 3 or 6 mmol / l.

Oxygen in isooctane at a concentration of TiCl ^ and

In preparing a preferred catalyst system, a TiCl, catalyst component is used which has been obtained by gradually adding TiCl. a trialkyl aluminum at temperatures lower than -30 C, particularly - ■ has added -50 to -90 ⁰ C and the resulting mixture brought to temperatures above 80 ⁰ C. In space-

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a molar ratio of TiGl 1: trialkylaluminum between 3: 0.9 and 3: 1.5 is generally used. The reaction is preferably allowed to proceed -50 to -90 ⁰ G, optionally an inert liquid dilution agent is used. After the reduction of the TiGl. the temperature is increased to over 80 ⁰ G _1, for example to 155 ° G. To activate the resulting TiCl-, molar ratios of dialkylaluminum halide: TiGl of 2: 1 × 3 5: 1 are favorable.

Another catalyst system is obtained by

Dialkyl aluminum halide, preferably diethyl aluminum chloride, with TiCl. at a temperature between -5 and -45 ° C in one Molar ratio between 0.5: 1 and 1.2: 1, preferably from 0.65: 1 to 0.85: 1, in a paraffinic diluent mixed with a specific stirring power of 50 to 2000 V / m reactor volume.

The monoalkylaluminum dihalide formed during the reaction between the two components can be removed from the mixture, for example by decanting, or e3. can, for example, be converted into dialkyl aluminum halide or into a complex with a Lewis base such as dibutyl ether. The temperature of the mixture is then increased to at least + 15G, further with a. Stirring power is stirred within the specified limits. The mixture is then heated to 70 to 20O ⁰ C. The polymerization with the resulting TiCl ^ component can then after the addition of an aluminum alkyl activator, preferably an amount of dialkyl aluminum halide, s ° that the

The final atomic ratio between Al and Ti is 1.5: 1 to 10: 1.

The alkyl groups in the aluminum alkyl compounds, which according to the invention are used for the reduction of TiGl ₄ or the activation of TiCl, can be branched or unbranched. As a rule, they contain no more than 12 carbon atoms. Ethyl groups are preferred. The halogen in the dialkyl ⁺ takes place,

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aluminum halide is preferably chlorine.

The polymerization with the aid of the "described catalyst systems, generally takes place in an inert liquid medium. Suitable solvents or diluents are "especially hydrocarbons and halogenated hydrocarbons. The hydrocarbons can be aliphatic ^, cycloaliphatic or aromatic compounds or mixtures of Be aliphatics and aromatics. Appropriate concentrations of Titanium compounds during the polymerization are generally 0.1 to 20 mmol Ti / l (1 mmol Ti = 154 mg TiCl-). As above said, it is desirable that the final atomic ratio of Al: Ti in the catalyst system is from 1.5: 1 to 10: 1. Higher however, lower concentrations are also possible. If desired, the polymerization can be carried out in the presence of substances which lower the molecular weight of the polymer, for example hydrogen.

Before the catalyst system is used for polymerization, however, it should be contacted with an amount of propylene into contact at a temperature below 62 C, preferably between 50 and 6O ⁰ C, so that at least 0.1 g, preferably 0.5 to 5 g, Polypropylene / g TiCl, are formed in the system. During this "prepolymerization ¹¹ it is favorable that the components of the catalyst system are present in a relatively high concentration (preferably 10 to 10,000 mmol / l) in a solvent or diluent such as isooctane.

The prepolymerization can be carried out in a simple manner by adding the desired amount of propylene to the catalyst system initiates, which has been brought to the desired temperature. While overpressure is not essential, can be used as long as it is below-Λτοη 2 bar. However, it is advantageous to carry out the prepolymerization - and also the polymerization - in an inert atmosphere, such as

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Nitrogen atmosphere.

The catalyst system used for the prepolymerization is adapted to bar (absolute) for propylene polymerizations under extreme conditions, ie, "at a temperature of 65 to 9O ⁰ C, preferably 70 ms 85 G and a propylene pressure of at least 2, preferably 4 to 45 bar to be applied.

If the polymerization is carried out in batches, can The prepolymerization can be carried out in the reaction vessel by first adding a small amount of propylene at a temperature below 65 G and a pressure below 2 bar to polymerize and then bring the temperature and pressure to the desired Polymerization conditions increased. In the preferred continuous polymerization, the prepolymerization takes place in a separate reaction vessel instead. The catalyst system used for the prepolymerization is introduced into the polymerization vessel under the polymerization conditions. One continuous polymerization is preferably carried out in a reaction vessel with stirring and homogeneous equilibrium conditions carried out.

When the polymerization is complete, the polymer can be further processed in any known manner. So can Catalyst residues can be removed by treatment with an acid and an alcohol.,

The propylene homo- or copolymer obtained according to the invention has a good bulk density, which is necessary for the polymerization, processing, transport and handling of the polymer is cheap. The polymerization can be continued up to a higher polymer concentration until the suspension fails more can be stirred. In addition, a higher bulk density leads to an increase in the capacity of the drying devices, transport devices and processing devices, such as strand

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pressing devices. The resulting polymer, which has a high isotactie owns, can with stabilizers, pigments, fillers etc. are mixed before further processing.

Examples

a) Preparation of TiCl: A 1 l reaction vessel which was filled with nitrogen gas was cooled to -70 ° C. with the aid of a mixture of dry ice and acetone. The reaction vessel was fitted with a stirrer rotating at a speed of 750 rpm. 290 cm of a mixture aus.triethylaluminum and isooctane (2,2,4-trimethylpentane) with an Al (GpR ₁ -) , concentration of 0.8 mol / l were added to the reaction vessel. 300 cnr of a mixture of TiCl. and isooctane (2 mol TiCl./l) were added dropwise within 4 h. The temperature was then ^{increased to 20 °} C. over the course of 2 h and then to this for 1 h. The value was held and then increased to 155 ° C. in 2 h and held at this value for 1 h. Then the reaction mixture was cooled min at 5O ⁰ C within 15 minutes.

b) Prepolymerization: Sufficient diethylaluminum chloride and isooctane were added to an amount of the desiananized. TiCl, was added, which was under a nitrogen atmosphere in a glass flask which was stirred, a concentration of 0.1 mol TiCl ₅ A being obtained. The molar ratio TiCl: Al (G ₂ H ₅ J ₂ Cl was 0.4 · The mixture was heated to 55 ° C. and 1 g propylene / g TiCl was added over the course of 10 minutes.

c) Example b) was repeated with the exception that 0.25 g propylene / g TiCl were added within 2.5 minutes.

d) Sufficient (CgHj-KAlOl and isooctane were added under nitrogen to an amount of TiCl obtained according to Example a), so that a concentration of 1 mol of TiCl ₃ and (C ₂ ^) ₂ AlCl (ratio Al: Ti 1 : 1) he

_{3 2} ^ ₂ held. 1.2 g of propylene / g TiCl, with stirring at 6O ⁰ C

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added within 1 h. It was found that 1.02 g polymer / g TiGl- had been formed.

e) Example d) was repeated, with the exception that 6.4 g propylene / g
were formed.

6.4 g propylene / g TiGl were added. 6.3 g polymer / g TiCl,

f) For comparison, example b) was repeated, with the exception that no propylene was added, so that no prepolymerization took place.

g) Polymerization: Investigations were carried out in a 3.2 liter metal reaction vessel carried out, which was provided with a stirrer and a heating or cooling jacket. The reaction vessel was with

3
1500 cm of isooctane filled, which had been flushed with nitrogen gas for 30 minutes. The stirrer was set to a speed of 330 μPM and then 6 mmol (GpH ₁ -) ₂ A1C1 were added. The reaction vessel was then filled with propylene to an overpressure of 5 bar (tests 2 to 5 inclusive) and brought to an addition temperature as indicated in Table B below, the nitrogen gas escaping from the reaction vessel. Then one of the TiCl, catalyst components which had been obtained in accordance with examples b) to f) was added. After 1 min the reaction vessel to the polymerization was, ie, a temperature of 7O ⁰ C and a propylene pressure of 7 bar accommodated. After the reaction vessel had been kept at these conditions for 4 hours, the pressure was released and 100 cm of isopropyl alcohol was added. The polymer was then isolated, washed twice with water, treated with steam to remove the volatile constituents, filtered and ^{dried under nitrogen at 65 °} C. and 160 mm Hg. Table B shows the bulk density and isotacticity of the resulting polymer.

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These polymerizations are repeated (experiments 6 and 7) with TiCl ^ catalyst components, which according to the examples d) and e) had been obtained at a higher pressure, namely a propylene pressure of 15 bar and a temperature of 65 C. The Addition of the TiCl ~ was also carried out at 65 C and a propylene overpressure carried out by 15 bar.

Table B.

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Table B.

Try TiCl, -

Catalyst component according to "Beisüiel

If activity (g polymer / g

TiCl ₃ "bar * h)

54

55

54

53

Addition conditions temperature pressure

( ⁰ C)

54

53

65 70

75 80

85 90

75 80

75 80

70 75

85

(bar)

15th

15th

Rubble
(gfcnr polymer
ichther extract
). (Wt .- ^) 0.36
0.29
0.13 1.9 _n
5.0 +)
6.4 +) 0.33
0.34
0.34
0.31 1.4.
1.3
1.4- _x
2.3 +) 0.29
0.29 2.0 +)
4.5 +) 0.33
0.35 1.2
1.5 0.35
0.34
0.35 0.7
1.9
1.7 0.36 0.7

0.39

0.9

+) The polymer had a wool-like appearance, which indicates a decomposition of TiCl, particles.

cn cn co

Claims (1)

Pat ent demands Method at a temperature of from 62 to 9O ⁰ G and a propylene partial pressure of at least 2 bar (absolute) in the polymerization vpn propylene in a liquid diluent "by addition of a catalyst system comprising TiCl, and a dialkylaluminum halide at this temperature, characterized in that the catalyst system had previously been contacted with sufficient propylene in a liquid diluent at a temperature below 62 O that at least 0.1 g polymer / g TiCl 2 was formed. 2. The method according to claim 1, characterized in that g e k e η η - ζ ei chnet that the catalyst system with so much propylene had been brought together that 0.5 to 5 g polymer / g TiCl., were formed. 3. The method according to claim 1 to 2, characterized in that propylene is homopolymerized. 4. The method according to claim 1 to 3, characterized in that there is a catalyst system with a characteristic activity of at least 30 g polymer / g TiGl ^ and h and bar propylene is used. 5. Method according to Claims 1 to 4, characterized in that indicates that a TiCl-z catalyst component is used used that has been obtained by-gradual 209851/10 59 ~ «" - 1A-41 474 Adding TiCl. to a trialkyl aluminum at temperatures
was then placed between -50 and -9O ⁰ C and the resulting mixture to temperatures of about 8O ⁰ C. 6. The method according to claim 5, characterized in that the molar ratio of TiCl. : Aluminum trialkyl 3: 0.9 to 3: 1.5. 7. The method according to claim 1 to 4, characterized in that one uses a TiCl ^ -Katalysatorkomponente which has been prepared by mixing dialkyl aluminum halide with TiCl. at a temperature of -5 to
-45 ° C in a molar ratio of 0.5: 1 to 1.2: 1 in one
paraffinic diluent using a specific stirring power of 50 to 2000 W / cm reactor volume and
then increasing the temperature to at least 15 ° C with further stirring with a specific stirring power in the
specified limits. 8. The method according to claim 1 to 7, characterized in that there is used as the dialkyl aluminum halide
Diethylaluminum chloride is used. 9. The method according to claim 1 to 8, characterized in that the titanium compound is in a consentration from 0.1 to 20 mmol Ti / l used in the polymerization . 10. The method according to claim 1 to 9, characterized in that there is an atomic ratio in the polymerization Al: Ti in the catalyst system from 1.5: 1 to 10: 1 applies. 209851/1059 - V- 1Α-41 474 IS * 1-1. , The method of claim 1 Ms 10, characterized by bringing the catalyst system "in the prepolymerization with propylene" at temperatures of 50 to 6O ⁰ C into contact. 12. The method according to claim 1 to 11, characterized in that the prepolymerization with propylene the catalyst components are used in a concentration of 10 to 10,000 mmol / l diluent. 13. Method according to claims 1 to 12, characterized in that g e k e η η ζ ei chnet that in the prepolymerization with propylene a propylene pressure of not more than 2 bar (absolute) applies. 14. Process according to Claims 1 to 13, characterized in that the polymerization is carried out at temperatures from 70 to 85 ° 0. 15. The method according to claim 1 to 14, characterized in that the polymerization is carried out at a propylene pressure from 4 to 45 bar (absolute). 16. The method according to claim 1 to 15, characterized in that the polymerization under homogeneous Performs equilibrium conditions with stirring in a reaction vessel. 17. Use of the process products according to claim .1 to 16 for the production of moldings. 20985 1/1059