DE2445355A1 - PROCESS FOR THE POLYMERIZATION OF ETHYLENIC NON-SATELLATED HYDROCARBONS - Google Patents

Description

"concerning:

" Process for the polymerization of ethylenic, unsaturated hydrocarbons"

The invention "relates to a method of polymerization of ethylenically unsaturated hydrocarbons in the presence of a catalyst which is a dialkyl aluminum halide and γ-TiCl ^.

TiCl ^ can be produced in various ways and can exist in several different forms (cf. Kirk-Othmer, 2nd edition, Vol. 20, pp. 385-387). Among these forms, the violet γ-form is most suitable for the polymerization of α-olefins such as propylene because it gives polymers that are highly crystalline. γ-TiCl ^ can be obtained, for example, by reducing TiCl ^, with organo-aluminum compounds at 150 to 200 ° 0; by reducing TiGl. with organo-aluminum compounds at low temperatures, for example between -20 and up to + 20 ° 0, and subsequent heating to over 80 ⁰ O

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or by reducing TiCl ^, with aluminum at high! temperature. IiOl. even at even lower temperatures, e.g. B. at -70 ° C, reduce with trialkylaluminum, whereupon it is then, as mentioned, ^{heated to over 80 0} C (see. US Pat. No. 3,562,239).

It is also known to pretreat γ-TiCl with diethylaluminum chloride (see Journal of Polymer Science, 1963, Part C, No. 4, pp. 49-69 and Journal of Polymer Science, 1967, Part A1, Volume 5, pp. 205-214). These pretreatments appear to increase the efficiency of the catalyst by 20 to 30 % .

It has now been found that a pretreatment of the initially by reduction of TiCl ^. γ-TiCl ^ obtained at very low temperatures can lead to an unexpectedly high increase in the catalyst efficiency of 50% and more, even of up to 100%. Apart from this considerable increase in the catalyst activity, the pretreatment also increases the overall activity of the process considerably, since the activity of the catalysts is very high right from the start.

The invention relates to a process for the polymerization of ethylenically unsaturated hydrocarbons in the presence of a catalyst comprising a dialkylaluminum halide and y-TiCl ^, which is characterized in that a γ-TiCL is used which has been obtained by reducing TiCl ^ with a Organo-aluminum compound at a temperature below -25 ° C, heating the resulting TiCl to a tempera ture between 80 and 300 ⁰ C, pretreatment of the TiCl, with a solution of a dialkyl aluminum halide in one

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liquid hydrocarbon and isolating the TiOl, from the hydrocarbon solution.

If the TiCl ^ is reduced at a temperature between -50 and -25 ° C, for example at -30 ⁰ C, a dialkyl aluminum halide, in particular diethyl aluminum chloride, is preferred and the molar ratio TiCl ^: dialkyl aluminum halide can be between 0.8: 1 and 2: 1, in particular between 0.85: 1 and 1.55 * 1. At lower temperatures, such as from -150 to-50 ⁰ C, for example at -70 or -100 ⁰ G, as the reducing agent is a trialkylaluminum, most preferably triethylaluminum the. In this EaIl the molar ratio TiGl ^: trialkylaluminum is expediently between 2: 1 and 3.3: 1 and in particular between 2.3: 1 and 2.85: 1.

The reduction is expediently carried out in a hydrocarbon which is at the reduction temperature is liquid. Examples of suitable hydrocarbons are propane, η-butane, isobutane, n-pentane, Hexane and isooctane (2,2,4-trimethylpentane). The reduction is carried out with advantage in such a way that one has a solution of TiCl ^, in the hydrocarbon of a solution of Organo-aluminum compound in the same hydrocarbon within at least one hour. The concentration of the TiCl ^ solution used is e.g. 1 to 6 moles per liter and that of the organo-aluminum solution is, for example, 0.1 to 5 moles per liter. During the reduction, the reaction mixture becomes expediently stirred vigorously, including a specific stirring force of 80 to 800 watts / ur reactor charge used (see Chemical Engineering Progress 46 (1950) 395-404 and 467-477.

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defining the term "specific stirring force").

Mach completion of the reduction is the mixture contains, the B-TiCl, preferably over several hours, to a temperature between 80 and 300 ⁰ C, preferably heated to 100 to 175 ° C to the ß-TiCl ₃ in γ-Tiou to convict.

In the pretreatment stage, the γ-TiCl is advantageously brought into contact with 0.05 to 10 mol, preferably 0.1 to 3 wt. Of dialkylaluminum halide per mol of TiCl. The dialkyl aluminum halide is used as a solution in a hydrocarbon solvent, for example as a 0.1 to 3 molar solution. The temperature of the pretreatment is between 0 and 100 ^° C., preferably 10 to 60 ^° C., and its duration is 0.1 to 5 hours. After the pretreatment, the TiCl is separated from the hydrocarbon solution, for example by decanting, filtering or centrifuging. If necessary, the isolated TiCl- can then be washed with a hydrocarbon.

During the pretreatment, the aluminum trichloride present in the γ-TiCl, is partially converted into an alkyl aluminum dichloride by reaction with the dialkyl aluminum halide. Lowering the molar ratio AlCl, / TiCl ₇ . seems from about 0.3 to 0.1 to 0.2

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to have a beneficial effect on catalyst activity. The aluminum dichloride formed is though a catalyst inhibitor, but it is soluble in the hydrocarbon solvent and therefore becomes in the isolation of the TiCl, largely removed. The last traces can be removed by washing out the TiCl, remove with a hydrocarbon solvent.

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Before the polymerization itself, it is often advantageous to carry out a prepolymerization using the γ-TiCl. To this end, the TiCl ^ is brought into contact with a sufficient amount of ethylenically unsaturated hydrocarbon in an inert hydrocarbon medium at a temperature below 62 ° 0, for example at 10 to 55 ° C, so that at least 0.1 g, in particular 1 to 50 g, of polymer per g of TiGl. It is advantageous if a certain amount _{of dialkyl aluminum halide, for example 0.75 to 1 mol per mole of TiCl 7} , is present during the prepolymerization. The prepolymerization can be carried out after the pretreatment, or if it is effected in the presence of a dialkylaluminum halide, it can also be carried out simultaneously with this pretreatment.

The ethylenically unsaturated hydrocarbons that polymerize with the aid of the process according to the invention are in particular alkenes with 2 to 6 carbon atoms, such as ethylene, propylene, butene-1 and pentene-1, vinyl aromatic compounds such as styrene, or dienes such as butadiene. The process according to the invention is also of interest for production of copolymers of 2 or more ethylenically unsaturated compounds.

The polymerization can be carried out with or without a diluent. Aliphatic, cycloaliphatic, and aromatic hydrocarbons are particularly suitable as diluents. Will the procedure If carried out "without diluent", no diluent is used except for the ethylenically unsaturated hydrocarbon are used, except that the latter contain small amounts of inert impurities can.

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During the polymerization, the TiOIz is used in a concentration which is expediently between 0.1 and 20 milliatoms Ti per liter. The molar ratio of dialkyl aluminum halide to TiCl? is expediently between 0.5: 1 and 10: 1, preferably between 2: 1 and 5: 1. The temperature is vorzugsweisejzwischen 20 and 150 °, in particular between 50 and 90 ⁰ G and the pressure between 1 and 50 bar abs. If no diluent is used, the pressure and temperature can be adjusted so that the polymerization medium is gaseous or liquid.

To ensure sufficient fluidity of the polymerization mixture, the solids content is maintained in the polymerization zone preferably below 60% by weight and in particular between 25 and 55% by weight.

The polymerization can optionally be carried out in the presence of hydrogen gas, whereby the molecular weight of the polymer is reduced. _{For example, 0.1 to 1% by volume of H 2 is} expediently present in the gas-filled part of the polymerization vessel during the polymerization of propylene.

The examples serve to explain the invention in more detail.

Example 1

A. Reduction of titanium tetrachloride

The reduction of TiCl. was under nitrogen in a 700 ml reactor (diameter about 9 cm) carried out. The reactor was equipped with a stirrer of the largest diameter 5 cm, whereby the

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Stirrer "moving volume was about 5% of the internal volume of the reactor. A solution of aluminum triethyl (19> 8 ml, 140 mmol) in n-pentane (155» 2 ml) was introduced into the reactor and this was then mixed with a mixture of liquid n-pentane and liquid nitrogen cooled to -100 ⁰ G. Within 3 hours of Aluminiumtriäthyllösung total of 400 millimoles of titanium tetrachloride in n-pentane was fed, which is a TiCl ^ concentration in the mixture of 2 mol / revealed liter. During the addition, the stirring speed was 300 rpm. Within a further 3 hours, the temperature of the mixture was now raised to room temperature, the stirring speed remaining unchanged. The mixture was then transferred to an autoclave, within 2 hours under nitrogen and with stirring to 155 to 160 ^° C. and held at this temperature for a further hour, whereupon it was finally allowed to cool to room temperature over 11/2 hours, the titanium trichloride was then separated off and examined microscopically. The particle size distribution was found to be very narrow and the average particle size was 12 µm.

B. Pretreatment with diethyl aluminum chloride

The pretreatment was carried out in one of the following three ways:

1) The titanium trichloride was mixed with a diethylaluminum chloride solution stirred in isooctane, while propylene was passed into the solution until per g of TiGl ;, 3 g of polypropylene had formed. That

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TiCl, was then filtered off and suspended in isooctane.

2) The titanium trichloride was stirred with a solution of diethyl aluminum chloride, then filtered off, washed with isooctane and resuspended in isooctane. The suspension was used in a prepolymerization reaction at 55 ⁰ C until per g TiCl, 20 g of polypropylene were formed was brought whereupon the polymerization at 70 ⁰ C in motion.

3) The titanium trichloride was based on that described under 2) Treated with diethylaluminum chloride, but without subsequent prepolymerization.

C. Polymerization of Propylene

The homopolymer! On of propylene was in isooctane in the presence of 0.6 vol .-% hydrogen under a pressure of 2 ^ bar (abs.) And carried out at a temperature of 70 ⁰ C. The catalyst consisted of 9 mmoles of diethylaluminum chloride and 4.5 mmoles of TiOl in 1.5 liters of isooctane. The polymerization time was 4 hours, followed by the addition of a

Solution of butanol in hydrochloric acid was terminated. The polymer was diluted with HCl and then with water washed and dried.

The table shows the results of several tests, with test a being a comparative test in which the TiCl, was not pretreated with diethylaluminum chloride.

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TABEL

Attempt.

Pretreatment

according to method - B. 3 B.1 B.2 B.2 B.2 B.1 B.1

Time, h - 5 0.5 3 3 5 0.17 0.5

Temp., ⁰ C - 25 40 25 25 25 40 40

Molar ratio

₂₃ - 1.2 1.0 0.15.0.5 0.6 1.2 0.75

Et ₂ AlCl solution

mmol / liter - 300 300 45 50 165 100 100

Polypropylene yield 44 68 86 57 83 84 79 75 g / g TiCl, / h / bar

Example 2

To in Example 1 A. described manner and in the same reactor titanium trichloride was prepared in isooctane at -30 ⁰ C. A 2 molar TiCl ^ solution in isooctane was added dropwise to a 0.8 molar solution of diethylaluminum chloride over a period of 4 hours. The ratio Al / Ti was finally 0.75 * The mixture was heated over 4 hours from -30 to +40 ⁰ C and within a further hour from 40 to 155 ⁰ C, at which latter temperature was maintained for one hour, after which it Was cooled to room temperature within a further hour. The resulting TiCl ₅ had an average particle size

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size of 16 / um.

The TiCl ^ was then pretreated with diethylaluminum chloride and prepolymerized according to Example 1 B.2, whereupon it was used for a propylene polymerization according to Example 10. The yield of polypropylene was 45 g / g TiOl, / h / bar, while without pretreatment they only offer 30 g / g TiCl, / h / bar fraud.

PATENT CLAIMS:

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Claims (9)

PATENTAL SPEECH Process for the polymerization of ethylenically unsaturated hydrocarbons in the presence of a catalyst composed of a dialkyl aluminum halide and γ-TiCl ,,, characterized in that a γ-TiCl, which was obtained by reducing TiCl ^, with an organoaluminum compound at a temperature below is used -25 ⁰ C, heating the resulting tiol, to a temperature between 80 and 300 ⁰ C, pretreating the TiCIv with a solution of Dialkylaluminiumhalogenides in a hydrocarbon and isolating the TiCl, from the hydrocarbon solvent. 2) The method according to claim 1, characterized ge was features to -50 ⁰ C reduced. that the TiCl ₄ at -I50 3) Method according to claim 2, characterized in that the TiGK with a Trialkylaluminum, preferably with triethylaluminum, was reduced. 4) Method according to one of claims 1 to 3 »characterized in that the resulting TiCl5 heated to a temperature of 100 to 175 ° C will. 509814/1044 -η - 5) Method according to one of claims 1 to 4 ·, characterized in that the Pretreatment using 0.1 to 3 moles of dialkyl aluminum halide per mole of TiOIv carried out. 6) Method according to one of claims 1 to 5> characterized in that the pretreatment using diethylaluminum chloride " performs. 7) Process according to one of claims 1 to 6, characterized in that the pretreatment is carried out at a temperature between 10 and 60 ^° C. 8) Process according to one of claims 1 to 7> characterized in that the TiCl _{2 is brought} into contact in an inert hydrocarbon medium at less than 62 ° with so much ethylenically unsaturated hydrocarbon that per g TiCl ;, 1 to 50 g polymer form. 9) Method according to one of claims 1 to 8, characterized in that as Ethylenically unsaturated hydrocarbon propylene is used. 50981 4/1 OU