DE1239854B - Process for the low-pressure polymerization or copolymerization of olefins - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C08f

German class: 39 c - 25/01

Number: 1239 854

File number: F25124IVd / 39c

Filing date: February 26, 1958

Open date: May 3, 1967

It is known, -olefins and diolefins, in particular ethylene, propylene and 1-butene and butadiene and isopropene, with catalysts of subgroups IV to VIII of the periodic system and reducing or alkylating compounds of I. to III. Group of the periodic table polymerize to high molecular weight polyolefins at relatively low pressures and temperatures. Particularly For such low-pressure polymerizations, catalyst mixtures made of titanium tetrachloride have been found or titanium subhalides with organoaluminum compounds. The ones with these Catalysts used in low-pressure polymerization processes are referred to as Ziegler catalysts and are z. B. in the Belgian patent 533,362 described.

In the polymerization of propylene and the higher -olefins with the aforementioned catalysts are in addition to well crystalline hydrocarbons used as dispersants also insoluble or sparingly soluble polymers under the polymerization conditions amorphous, readily soluble polymers and oils are obtained. According to Natta, those are well crystallizing Polymers are sterically ordered and are called "isotactic", while the soluble polymers are sterically disordered and are called "atactic".

Little is known about the mechanism of action of the Ziegler catalysts. It has been shown that the reaction of TiCl ₄ and organoaluminum compound results in a reduction of the tetravalent titanium. For example, the reaction of TiCl ₄ with AlR ₃ creates a trivalent titanium compound that can be further reduced to divalent titanium.

TiCl ₄ + AlR ₃ -v R '+ TiCl ₃ + AlR ₂ Cl · ■ - ** &

Equation IR '+ TiCl ₂ + AlR ₂ Cl

Equation Π

When using halogen-containing aluminum alkyl compounds, such as mono- or dialkyl halides of the type AlR ₂ Hal or AlRHaI ₂ (R = alkyl) or a mixture of these compounds, the sesquihalides, a reduction occurs only to the trivalent Ti compound, e.g. B.

TiCL + A1R "

AlR ₂ shark

TiCL + AlRHaL

TiCl ₃ + AlRHaI ₂ + R '

Equation ΙΠ

TiCl ₃ + AlHaI ₂ + R '

Equation IV

Process for the low pressure polymerization or copolymerization of olefins

Applicant:

Farbwerke Hoechst Aktiengesellschaft formerly Master Lucius & Brüning, Frankfurt / M.

Named as inventor:
Dr. Kurt Rust, Frankfurt / M.-Eschersheim; Dr. Siegfried Sommer, Unterliederbach; Dr. Günther Lehmann, Neuenhain (Taunus); Dr. Günther Peters, Frankfurt / M.-Höchst

When using AlR ₃ as reducing agent, the AlR ₂ Cl _{formed according to equation I reacts quantitatively with TiCl 4} according to equation III to form AlRHaI ₂ .

In the polymerization of α-olefins of the R — CH = CH _{2 type} , where R = H or a hydrocarbon radical of up to 8 carbon atoms, it has been found that the presence of aluminum monoalkyl dihalides in particular has an unfavorable influence on the rate of polymerization. According to German Auslegeschrift 1019 466, therefore, in ethylene polymerization, the TiCl ₃ contact obtained by reduction with organoaluminum compounds is used before polymerization with inert solvents, such as low-olefin petroleum fractions, saturated aliphatic

. table or cycloaliphatic hydrocarbons. Most of the aluminum monoalkyl dihalide is removed _{from the TiCl 3} suspension by an intensive washing process. In ethylene polymerization, such a contact gives more reproducible results in terms of polymerization rate and molecular weight than an unwashed TiCl _s contact. In the polymerization of α-olefins, in particular propylene, a well-washed TiCl ₃ contact with a suitable activation, e.g. B. obtained with aluminum dialkyl monochloride, a satisfactory space-time yield and a largely sterically uniform, isotactic polymer. According to an older, not part of the state of the art

709 578/335

The stereospecificity can be increased further if the TiCl ₃ contact is subjected to a thermal treatment and this contact is washed before and / or after the heat treatment.

To use for the preparation of TiCl ₃ -KOntaktes the reaction of TiCl ₄ with aluminum-organic compounds without further treatment (washing and thermal treatment), such as is described by Natta et al (Gazz. Chim. Ital., 87, Fase. V, S. 528, 549, 570 [1957]), this normally gives catalysts which are only slightly selective in the α-olefin polymerization. In contrast, according to Natta (cf. literature above), selectively acting contacts are obtained from aluminum triethyl and microcrystalline TiCl _{3 , which is produced from TiCl 4} and H ₂ by the technically more difficult method to be carried out at high temperatures. The rate of polymerization is, however, considerably slower than with a _{TiClg contact made from TiCl 4} and an organoaluminum compound which has been post-treated, as mentioned above.

Also in the laid out documents of Belgian patent 549 909 is a process for polymerisation of olefins using a catalyst system according to Ziegler, which from consists of two components:

1. The reaction mixture that arises when a compound of a metal of IV., V., VI. or VIII. Subgroup of the periodic system or of manganese with a organometallic compound of an alkali metal, alkaline earth metal, zinc, an earth metal or rare earth metal.

2. A halogen-free, organometallic compound of an alkali metal, alkaline earth metal, zinc, of an earth metal or rare earth metal.

When using an excess of halogen-free organometallic compounds as a catalyst component However, 2 becomes a when polymerizing -olefins with more than 2 carbon atoms higher proportion of undesired products which are soluble in the dispersant are obtained.

The invention relates to a process for the low-pressure polymerization of olefins of the formula CH ₂ = CHR, where R is hydrogen or a hydrocarbon radical with up to 8 carbon atoms, or copolymerization of these olefins with one another in an inert dispersant and / or in the presence of the liquid olefin a catalyst, which is produced by reacting titanium tetrachloride with aluminum _{diethyl monochloride or aluminum ethyl sesquichloride in a molar ratio of TiCl 4} to the organoaluminum compounds mentioned 1: 0.5 to 1: 2 at temperatures below 40 ° C in oxygen-free, desulphurized, dried olefin-free petroleum fractions, if necessary by subsequent thermal treatment of the formed TiCl ₃ containing suspension prepared at 40 at 150 ⁰ C, and by adding Alummiumtriäthyl after complete reduction of TiCl ₄ to TiCl _3, characterized in that polymerization in the presence of a catalyst prepared by train Abe of aluminum triethyl has been prepared in an equimolar amount of the aluminum monoethyl dichloride present.

The advantage of this procedure is that the aluminum ethyl dihalide contained in the contact mother liquor is converted into a polymerization-active compound and the _{organoaluminum compound used to reduce the TiCl 4 is} largely used for the polymerization, while it is discarded in the washing process. Another great advantage is that the difficult filtration of the _{TiCl 3} suspension can be avoided during the washing process and no solvent has to be used for a washing process.

The amount of aluminum triethyl which is added according to the invention depends on the content of aluminum monoethyl dihalide _{in the TiCl 3 suspension.} This depends on the type and amount of the organoaluminum compound that is used to reduce the TiCl ₄ . This can be explained with a few examples:

1. If you let z. B. 1 mole of titanium tetrachloride with

1 mole of aluminum diethyl monochloride react, so according to equation III I moles of TiCl ₃ and 1 mole of aluminum monoethyl dichloride are formed. To convert it into the polymerization-active aluminum diethyl monochloride, 1 mole of aluminum triethyl is required, and according to the invention it is precisely this amount that is added to the unwashed titanium trichloride suspension.

2. When reacting 1 mole of titanium tetrachloride with 1 mole of aluminum ethyl sesquichloride, d. H. an equimolecular mixture of aluminum diethyl monochloride and aluminum monoethyl dichloride, arise according to equation V.

2 moles of aluminum monoethyl dichloride, according to the invention 2 moles of aluminum triethyl to remove it be added to the titanium trichloride contact.

TiCl ₄ + A1 (C ₂ H ₅ ) ₂ C1 + Al (C ₂ H ₅ ) Cl ₂
-> TiCl ₃ + 2Al (C ₂ H ₅ ) Cl ₂ + C ₂ H ₅ '

Equation V

3. The reaction of 2 moles of titanium tetrachloride with 1 mole of aluminum ethyl sesquichloride is formed according to equation VI per mole of titanium trichloride 0.5 mole of aluminum monoethyl dichloride.

2TiCl ₄ + A1 (C ₂ H ₅ ) ₂ C1 + Al (C ₀ H ₅ ) Cl ₁ ,

-> 2TiCl ₃ + Al (C ₂ H ₅ ) Cl ₂ + AlCl ₃ + C ₂ H ₃ -

Equation VI

that is, 0.5 mole of aluminum triethyl is added per mole of TiCl _{3 according to the invention.}

With other ratios of TiCl ₄ to organoaluminum compound when making the contact, the content of aluminum monoalkyl dihalide can accordingly be easily calculated or determined analytically.

When TiCl _{4 is} reacted with halogen-containing organoaluminum compounds in inert solvents, titanium tetrachloride, aluminum trichloride (when using aluminum monoethyl dichloride, equation IV) and aluminum monoalkyl dichloride (equation III when using aluminum dialkyl monochloride as reducing agent) are produced, as can be seen from the above equations. Of these reaction products, TiCl ₃ and AlCl _{3 are} insoluble in the inert hydrocarbons

I 239 854

and get out. The mother liquor can theoretically _{contain unreacted TiCl 4} , aluminum monoalkyl dichloride and aluminum diethyl monochloride, the presence of TiCl ₄ in the presence of organoaluminum compounds being unlikely, especially in the case of contacts which are subjected to thermal treatment after the reaction. In fact, no soluble titanium compound in the mother liquor could be found in the contacts. The analytical determination of the content of halogen-containing organoaluminum compounds in the mother liquor is carried out by determining the Al content (decomposition with alcohol — benzene, hydrolysis with HoO and in H ₀ SO ₄ in the presence of KF, back titration with NaOH) and the Cl content Vol-hard (decomposition and hydrolysis as with Al determination) and the alkyl group content (hydrolysis with H ₂ O, volumetric measurement and gas chromatographic analysis of the split off reaction products). _{The content of AlR 2} Cl and AlRCl ₂ in the mother liquor can easily be calculated from the content of Al, Cl and alkyl groups. In the event that no AlR ₂ Cl (R = C ₂ H ₅ ) can be detected in the IR spectrum in the contact mother liquor (bands at 18.35; 15.92 and 14.81 after prior complexation of the Al (C ₂ H ₅ ) Cl ₂ with NaCl by heating for 1 hour at 80 ° C), Al and alkyl group determination can be dispensed with. A simple titration according to Vo lh ard is sufficient.

The reaction of the TiCl ₄ with the mentioned chlorine-containing aluminum alkyl compounds is carried out in oxygen-free, desulphurized, well-dried, olefin-free petroleum fractions. The molar ratio of VOnTiCl ₄ to the chlorine-containing aluminum alkyl compound varies between 1:> 0.5 and 1: 2.

When making the contacts, the reaction rate is strongly dependent on the concentration the reactant and the temperature. The higher the concentration, the greater it is and the temperature are. You can establish contact z. B. in 0.1 to 3 molar concentration make. It is advantageous to work in an imolar concentration.

The temperature at which the contact is made is of great importance. If you take z. B. the implementation the heavy metal compound with the organometallic compound at higher temperatures, z. B. at 40 to 100 ° C, then the conversion rate is high, but during the polymerization of «-olefins, activated with the organometallic compound, such a contact shows one low polymerization rate and leads to mixtures of amorphous and crystalline polymers. It is therefore necessary to carry out the reaction at temperatures below 40 ° C., which is advantageous below 20 ° C.

When carrying out the reduction of the TiCl ₄ with the said halogen-containing organoaluminum compounds, one can proceed in such a way that one reactant, for example the titanium tetrachloride, is initially introduced and the other is added, but one can also proceed in such a way that both components are put into the reaction vessel at the same time smuggled in.

The addition of the aluminum ethyl takes place after the reduction of the titanium tetrachloride to titanium trichloride is complete. It is advantageous to subject the unwashed _{TiCl 3} suspension to a thermal treatment at 40 to 150 ° C. before the trialkyl addition (cf. patent application F 22922 IVb / 39 c, German Auslegeschrift 1109 894). As a result of this thermal treatment, aluminum ethyl dichloride included _{in the TiCl 3 particle diffuses out and dissolves.}

After the addition of the aluminum triethyl to such an unwashed, thermally treated _{TiCl 3} suspension, the mixture can advantageously be heated to 60 to 100 ° C. for 10 to 60 minutes to complete the reaction. The conversion of the aluminum monoethyl dichloride with the aluminum triethyl takes place according to the known equation VII.

AlRCl ₂ + AlR ₃ ■

2AlR ₂ Cl

Equation VII

The polymerization of olefins of the CH ₂ = CHR type, where R represents hydrogen or a hydrocarbon radical of up to 8 carbon atoms, or the interpolymerization of these olefins with one another can be carried out batchwise or continuously at low pressures of, for example, 1 to 30 atm so that either the _{TiCl 3} -SuS-pension, which after the inventive treatment with aluminum triethyl contains the activator necessary to initiate the polymerization in the form of aluminum diethyl monochloride, is initially introduced or is added during the polymerization. The polymerization can be carried out in an inert dispersant and / or in the liquid olefin. The polymerization temperature is generally below 100 ° C.

example 1

A. Catalyst manufacture

In a 6-1 four-necked flask are placed under exclusion of air and moisture 3535 ecm of an olefin-free diesel oil fraction from boiling point 200 to 250 ° C and 613.35 ecm of aluminum ethyl sesquichloride (= 2.75 mol [1 mol of aluminum ethyl sesquichloride = 1 mol Al diethyl monochloride + 1 mol Al monoäthyldi-

4S chloride]), the solution was cooled to -3 ° C and then 550 ecm of distilled titanium tetrachloride (= 5 mol) were uniformly added dropwise within 2V2 hours with stirring. An internal temperature of 0 ° C. is maintained by cooling. A red-brown, fine precipitate of titanium trichloride separates out. For post-reaction, the batch is kept at 0 ° C. for 4 to 5 hours and left to stand at room temperature overnight. A solution of 387.25 ecm aluminum triethyl (= 2.75 mol) is then added dropwise with stirring at room temperature. The TiCl ₃ content is determined after hydrolysis with dilute sulfuric acid by titration with a cerium (rV) solution.

Q B. Ethylene Polymerization

In a stirred vessel contents of 3.51, equipped with stirrer, gas inlet tube and thermometer, a well deoxygenated saturated hydrocarbon mixture of boiling range 200 to 250 ⁰ C are introduced at 50 ° C 21st 20 mmol of the organoaluminum compound-containing TiCLj catalyst described under A are added under nitrogen. Then you pass ethylene

into the reaction mixture and allows the temperature to rise to 80.degree. The polymerization starts after a few minutes. After 6 hours, the polymerization is stopped by adding 50 ecm of n-butanol. In order to completely remove the dispersant, the polyethylene is subjected to steam distillation after suction on a suction filter. 600 g of polyethylene were obtained, which corresponds to a space-time yield of 50 g / l · h. The polyethylene thus obtained has a y _spec ic ^of 20 (measured 0.5% in tetrahydronaphthalene at 120 ° C). The bulk density is 300 g / l. When pressed to form sheets, the polymer exhibits a tensile strength of 280 kg / cm 2 and a ball indentation hardness of 470 kg / cm 2.

C. Propylene Polymerization

In a 3.5-1-polymerization vessel provided with a thermometer, gas inlet tube and stirrer, olefin-free diesel oil fraction are presented to the boiling point of 200 to 250 ° C as a dispersant at 50 ⁰ C with the exclusion of atmospheric oxygen and water 21 and under nitrogen, 20 mmol the TiCl ₃ suspension contained in Example 1 under A, containing organoaluminum compound. Propylene is then passed into the reaction mixture. The polymerization starts immediately. The temperature is kept at 50 ° C. by cooling. After 5 hours, the polymerization is stopped by adding 100 ecm of butanol, the mixture is stirred twice with water, the suspension is suctioned off on a suction filter and the residue on the suction filter is washed twice with a warm dispersant the end. Steam distillation is carried out to completely remove the dispersant from the insoluble polypropylene. After drying (in a vacuum at 50 ° C.), 250 g of crystalline polypropylene are obtained. _spi , _{2 / t} . = 5.3 (measured in 0.1% decahydronaphthalene solution at 135 ° C).

To determine the amorphous or oily content in the polymerization dispersant, a Sample processed as follows:

The polymer dispersion is filtered off with suction, the residue is washed out well and the mother liquor is removed and the combined washing solutions were concentrated to dryness in vacuo. A waxy one is obtained Residue in an amount of 10%, based on the total polymer.

Example 2 5 <>

A. Catalyst manufacture

The catalyst preparation described in Example 1 under A is modified so that the mixture is ^{heated to 100 °} C. for 3 hours before the addition of the aluminum triethyl. After cooling, the specified amount of aluminum triethyl is added.

C. Propylene Polymerization

B. Ethylene polymerization

60

The polymerization is carried out in a 3.5-1 polymerization vessel under the same conditions and with the same amount of the catalyst prepared according to A, as indicated in Example 1 under B. After an hour of polymerization, 500 g of polyethylene are obtained. rj _spec i _c = 25 (measured in 0.5% tetrahydronaphthalene solution at 120 ° C.).

The polymerization is carried out in a 3.5-1 polymerization vessel under the same conditions and with the same amount of the catalyst described under A, as indicated in Example 1, B. 290 g of polypropylene are obtained with a polymerization time of 5 hours. >] _{spec: t:} = 10.37 (measured 0.1% in decahydronaphthalene at 135 ° C). A soluble polypropylene content of 3.7% is found in the mother liquor (based on the total polymer).

The crystalline polypropylene shows by compression into plates (190 ⁰ C) has a ball indentation hardness of 715 kg / sq cm and a flexural strength of 460 kg / sq cm.

Example 3
A. Catalyst manufacture

2.831 n-heptane and 981.2 ecm of aluminum ethyl sesquichloride (= 4.4 mol) are placed in a 6-1 four-necked flask with the exclusion of air and moisture. The solution is cooled to -2 ⁰ C and then at a dropping rate of 10 cc per minute 438.4 cc of titanium tetrachloride (= 4.0 mol) was added dropwise. A red-brown, fine precipitate of titanium trichloride separates out. The suspension is stirred for a further 8 hours at 0 to -2 ° C, then left to stand overnight at room temperature and then heated for 3 hours at 100 ° C with stirring. The suspension is then cooled to 0 ° C. At this temperature and at a rate of about 10 ecm per minute, 1.185 liters (= 8.4 mol) of aluminum triethyl are added dropwise with stirring.

B. Propylene Polymerization

990 ecm of n-heptane are placed in a 2-1 four-necked flask equipped with a stirrer, thermometer and gas inlet tube and the air is displaced by nitrogen. _{Then 10 mmol of the TiCl 3} catalyst described under A are pipetted in at 50 ° C. and propylene is immediately introduced. The polymerization starts after a few minutes. The temperature is kept at 50 ° C. by cooling. After a polymerization time of 5 hours, the polymerization is terminated by adding 50 ecm of n-butanol. The work-up is carried out as indicated in Example 1 under C. 250 g of polypropylene are obtained. % _pez / _c = 8.7 (measured 0.1% in decahydronaphthalene at 135 ° C). A soluble polypropylene content of 3.5% is found in the mother liquor (based on the total polymer).

Claims (1)

Claim: Process for the low-pressure polymerization of olefins of the formula CH ₂ = CHR, where R denotes hydrogen or a hydrocarbon radical with up to 8 carbon atoms, or copolymerization of these olefins with one another in an inert dispersant and / or in the liquid olefin in the presence of a catalyst which by Implementation of titanium tetrachloride with aluminum diethyl monochloride or aluminum ethyl sesquichloride in a molar ratio of 9 10 TiCl ₄ to the mentioned organoaluminum characterized in that one in Ge Compounds 1: 0.5 to 1: 2 polymerized at temperatures in the presence of a catalyst which below 4O ⁰ C in oxygen-free, desulfurized, by adding aluminum triethyl in one dried, olefin-free petroleum fractions, ge the existing aluminum monoethyl dichloride if necessary, has been produced by a subsequent thermal equimolar amount. treatment of the formed TiCl _{3 containing sus-} pension at 40 to 150 ° C and by adding pamphlets considered: Aluminum triethyl after complete reduction. Interpretative documents of the Belgian patents of the TiCl _{4 has been produced} to TiCl ₃ , there- no. 549 909, 553 478. 709 578/335 4.67 © Bundesdruckerei Berlin