DE1795272C2 - Process for homo- and mixed polymerization of ethylene - Google Patents

Description

30th

It is known that a-olefins and their Can polymerize mixtures according to the Ziegler low-pressure process. They are used as catalysts Compounds of the elements of IV. To VI. Subgroup of the periodic table mixed with organometallic Compounds of the elements of I. to III. Group of the periodic table and generally works in Suspension, in solution or in the gas phase.

There are also known methods in which the catalyst components in conjunction with a Carrier can be used.

So z. B. according to the method of French patent specification 11 98 422 the compounds of IV. to VI. Subgroup of the periodic table with carriers such as bentonite. Pumice stone, kieselguhr, calcium phosphate, Treated silica gel, etc. and then reduced with organoaluminum compounds. With this one In the process, the polymerization takes place independently of the composition of the carrier material; of importance is therefore only the composition of the catalysts fixed on the carrier. Is disadvantageous before above all, that a catalyst and carrier removal is essential for further processing of the polymers is.

Furthermore, on the basis of German patent specification 12 14 653, there is a process / ur production of supported catalysts became known in the metal oxides with an average particle size of less than 0.1 micron with compounds of the general formula

TO ₄ X ₄

implemented.

Here, T denotes a metal from groups IVa, Va, Via, VIIa or VIII of the Periodic Table, O = oxygen, <x 0 to 2, X a halogen and b a number from 1 to 6.

The metal oxide used must not contain any form of molecularly bound water. if If the metal oxide comes into contact with water vapors, a very low catalyst is produced Activity.

The polymerization yields by this process are, however, even when using anhydrous Metal oxides and so low, even at pressures as high as 190 atmospheres, that a subsequent catalyst or carrier removal from the polymer can not be dispensed with if one technically wants to get a usable product.

In technology, however, polymerizations according to the Ziegler process can only be carried out with carrier contacts then simply carry out if further processing of the polymers without removal of the catalyst and support is possible. However, the amounts of catalyst remaining in the polymer, in particular the chlorine content should only be very low, so that neither discoloration of the polymers nor corrosion damage occur on the processing machines.

A method for homopolymerization has now been found of ethylene and copolymerization of ethylene with up to 10 wt .-% of an α-olefin of Formula R-CH = CHi, where R is straight-chain or branched, substituted or unsubstituted Alkyl radical with 1 to 10 carbon atoms means, in solution, in suspension or in the gas phase, at Temperatures from 20 to 150 "C. At pressures up to 50 at, in the presence of a mixed catalyst, consisting of a titanium-containing component (component A) and an organoaluminum compound (component B), optionally with regulation of the molecular weight by hydrogen, characterized in that the polymerization in the presence of a Carries out mixed catalyst, the titanium-containing component by reacting a titanium compound of the formula

TiCI _n (OR) ₄ - ".

in which / 7 = 2 to 3 and R is iso-propyl, in the presence of an aliphatic, cyclophatic or aromatic hydrocarbon at temperatures from 0 to 60 ⁰ C with water in the presence of magnesium oxide and / or magnesium hydroxide, the molar ratio of titanium compound to Water is 1: 0.2 to 1: 6.

It was extremely surprising and by no means predictable for the person skilled in the art that the implementation of halogen-containing tetravalent titanium compounds with water in the presence of magnesium oxide and / or magnesium hydroxide, very active supported catalysts are formed; because in the German patent specification 12 14 653 it is expressly emphasized that no active supported catalyst due to the presence of water can be obtained. In contrast, supported catalysts are, according to the claimed Process are produced, but significantly more active than supported catalysts according to the German mentioned Patent specification.

Halogen-containing tetravalent titanium compounds of the general formula TiCl _n (OR) ₄ - ,,, in which n = 2 to 3 and R is iso-propyl, such as Ti (OiC ₃ H _{7 I 2} Cl ₂ .

The halogen-containing, tetravalent titanium compound is in an aliphatic, cyclophatic or

dissolved aromatic hydrocarbon and in the presence of magnesium oxide and / or magnesium hydroxide with stirring at temperatures from 0 to 60 ⁰ C in portions with water in a molar ratio of titanium compound to water, such as 1: 0.2 to 1: 6, preferably 1: 0.5 to 1 : 3, implemented.

If the carrier does not react with water or only binds water in the form of crystal water, can you can also mix it with water before the reaction. Then the water-containing carrier with the Titanium compound reacted, and it is expediently added in portions to the titanium compound with stirring is given.

Water or aqueous bases react with halogen-containing titanium compounds to form in Hydrocarbons-insoluble titanium compounds. Since the reaction in the presence of a solid as Support for the insoluble titanium compound takes place, a titanium-containing supported catalyst is formed.

The titanium-containing supported catalyst, which is insoluble in hydrocarbons, is washed with it several times an inert solvent in which the halogen-containing titanium compound used dissolves easily, of no reacted titanium compound freed.

Advantageously, a magnesium oxide is used as the carrier, which by thermal decomposition of MgCOj or Mg (OH): arises and has a bulk density of less than 200 g / l. Mixtures of MgO can also be used other metal compounds are used.

Since tetravalent halogen-containing titanium compounds react very quickly with water, carriers can also be used that react with water, such as magnesium oxide, which is advantageously used, since the Reaction of the water with the halogenated titanium compound proceeds preferentially.

The titanium content in the supported catalyst is expediently 0.05 to 15 mg atoms, preferably 1 to 10 mg-atom Ti per gram of supported catalyst.

The titanium content in the supported catalyst can be determined by the molar ratio of titanium compound to water as well influence by the amount of carrier used.

The conversion of the tetravalent titanium compound in the supported catalyst into the polymerization-active, lower valence stage is expediently carried out during the polymerization by the organoaluminum compound at temperatures from 20 to 120 ^° C., preferably 50 to 100 ^° C.

However, the catalyst may also litanhaltige carrier prior to polymerization with the organoaluminum compound at temperatures from -30 to 100 ^0C, preferably 0 to 20 ⁰ C, treated. When using chlorine-containing organic aluminum compounds, however, it is advantageous to wash the reaction product obtained. This is followed by activation with organoaluminum compounds at temperatures of 20 to 150 ° C., preferably 50 to 100 ° C.

As organoaluminum compounds, the reaction products of aluminum trialkyl or aluminum dialkyl hydrides with hydrocarbon radicals having 1 to 16 carbon atoms, preferably Al (iBu) i or AlfJBu) ₂ H and diolefins containing 4 to 20 carbon atoms, preferably isoprene, can be used; for example, aluminum isoprenyl may be mentioned.

Also suitable are organoaluminum compounds containing chlorine, such as dialkylaluminum monochlorides of the formula R2AICI or alkylaluminum sesquichlorides of the formula R ₃ Al ₂ Cl ₃ , where R can be identical or different hydrocarbon radicals, preferably alkyl radicals having 1 to 16, preferably 2 to 12 carbon atoms. Examples are:

(C ₂ Hs) ₂ AlCl, (IC ₄ Hg) ₂ AlCl, (C ₂ H ₅ J ₃ Al ₂ Cl ₃ .

_{Aluminum trialkyls AIR 3} or aluminum dialkyl hydrides of the formula AI R ₂ H, in which R are identical or different hydrocarbon radicals, preferably alkyl radicals having 1 to 16, preferably 2 to 6 carbon atoms, such as Al (C ₂ Hs) ₃ , AI (C _{2), are advantageously used} Hs) ₂ H, Al (C ₃ H ₇ J ₃ , AI (C ₃ H ₇ J ₂ H,
Al (iC4H ₉ ) ₃ , Al (iC ₄ H,) ₂ H.

The organoaluminum component can be used in concentrations of 0.5 to 10 mmol, preferably 2 up to 4 mmol can be used per liter of dispersant or per liter of reactor volume.

The polymerization can be in solution, at temperatures of 20 to 150 ° C, preferably 50 to 100 ⁰ C, carried out in suspension or in the gas phase, continuously or batchwise. The pressures are up to 50 at, preferably 1.5 to 8 at.

The inert ones customary for the Ziegler low-pressure process are suitable for suspension polymerization Solvents such as aliphatic or cycloaliphatic hydrocarbons; as such are for example Pentane, hexane, heptane, cyclohexane, methylcyclohexane are given. Furthermore, aromatic hydrocarbons, such as benzene, xylene, or gasoline or hydrogenated diesel oil fractions, which are used carefully have been freed from oxygen, sulfur compounds and moisture.

For the copolymerization, olefins of the general formula R-CH = CH ₂ are used, where R is a straight-chain or branched, substituted or unsubstituted alkyl radical having 1 to 10, preferably 1 to 8, carbon atoms. For example, propylene, butene- (I), pentene- (I), 4-methylpentene- (I), octene- (I) may be mentioned.

There are ethylene or mixtures of ethylene with up to 10 percent by weight, preferably up to 5 Percentage by weight of α-olefins of the general mentioned Polymerized formula.

The molecular weights of the polymers can be regulated in a known manner; preferably will do so Uses hydrogen.

The use of the claimed supported catalysts represent a major technical advance because the supported catalysts can be prepared very easily and already in one for the Ziegler polymerization The usual pressure range of 4 to 9 atm gives such high polymerization yields that the supported catalyst may remain completely in the polymer.

In the case of suspension polymerization, such complex operations as catalyst decomposition, Catalyst and support removal. After filtration from the dispersant, it is dried and further processing directly. The extremely low catalyst and amounts of carrier cause neither discoloration of the polymers nor corrosion damage on the processing machines.

In addition, when the TiCl ₂ (OiCjHy) ₂ mentioned as preferred is reacted with water in the specified molar ratio in the presence of magnesium oxide or magnesium hydroxide, a supported catalyst is formed, which after activation with aluminum trialkyls or aluminum dialkyl hydrides in the polymerization of ethylene or of ethylene with up to 10 percent by weight of Λ-olefins polymers with very close

Molecular weight distribution and interesting application technology Provides properties, where the

Values between 2 and 6 are.

The products obtained in this way have excellent color and corrosion properties and are particularly suitable for the production of injection molded articles.

example 1
I. Representation of the carrier analyzer

40 g of magnesium oxide ( "easy", Merck AG) with a bulk density of about 120 g / l at 10 ^Q C in 500 ml of a 1 molar TiCl ₂ (OiC3H _7)> - solution suspended in cyclohexane and with stirring and Nitrogen blanket was added dropwise with 11 ml (= 560mMol) of water within 30 minutes. Stirring is continued for 2 hours at 20 ⁰ C. Subsequently, the precipitate is washed by decanting and stirring ten times with 200 ml of cyclohexane. The cyclohexane above the solid should be free of titanium compounds. The volume of the suspension is made up to 600 ml.

The titanium content of the suspension is determined colorimetrically with hydrogen peroxide (G. O. Müller, internship of quantitative chemical analysis, 4th ed. [1957], p. 243). 10 ml of suspension contain 4.3 mM oil Titanium compound.

II. Polymerization of ethylene

a) 100 liters of diesel oil with a boiling range of 140 to 200 ° C are placed in a 150-liter boiler, the air is displaced by flushing with pure nitrogen and the boiler contents are heated to 80 to 85 ° C. A solution of 54 g (400 mmol) of aluminum triethyl in 500 ml of diesel oil and 120 ml of a suspension of the supported catalyst (prepared according to I.) is then added. The polymerization is carried out at 85.degree. With stirring, 6 kg of ethylene per hour and so much hydrogen are introduced that the hydrogen content in the gas phase is 30 percent by volume. The pressure rises to about 7 al in the course of the polymerization. After 7 hours, the polyethylene formed is separated off from the dispersant by filtration and dried. About 41 kg of polyethylene with a η _{ψι /} / σ value = 2.1 (measured in 0.1% igcr dcahydronaphthalene solution at 135 ° C.) are obtained. A polyethylene with a very narrow molecular weight distribution | - ^ - = 3.6) is obtained.

\ Mn I.

Mw

10

15th

20th

25th

30th

th.
The-

Mn

• Values were taken from the fractionation data of the

Gel permeation chromatograph from Waters (US) in 1.2.4-trichlorobenzene as solvent and elution medium determined at 130 C.

The polymer shows excellent color and corrosion values and can be injection-molded process well.

Example 2
Copolymerization of ethylen-bulk

In a 150-l-Kcsscl there are 1001 diesel oil with submitted to a Sicdcbercich from 140 to 200 ° C, displaced the air by flushing with pure nitrogen and the Kessclinhall is heated to 80 to 85 ° C. Then a solution of 79.2 g (400 mmol) of aluminum triisobulyl in 500 ml of diesel oil and 110 ml of suspension of the support catalyst (prepared according to 1 I.) are added.

50

55

60

65 The polymerization is carried out ^{at 85 ° C.} B kg of ethylene and 1:80 g of butene (1) per hour and so much hydrogen are introduced that the hydrogen content in the gas phase is 20 percent by volume. The pressure rises to about 7 atm in the course of the polymerization. After 7 hours, the resulting ethylene-butene mixed polymer is separated from the dispersant by filtration and dried. About 42 kg of an ethylene-butene mixed polymer with a value = 2.6 (measured in 0.1% strength decahydronaphthalene solution at 135 ° C.) and a density of 0.933. The product shows excellent color and corrosion values.

Example 3
I. Representation of the supported catalyst

10 g of magnesium oxide ( "easy", Merck AG) with a bulk density of about 120 g / l at 20 ⁰ C in 140 of a 1 molar TiCl ml ₂ (OiCjH ₇₎ suspended 2 solution in cyclohexane, and with stirring and With a nitrogen blanket, 5.04 ml (= 280 mmol) of water were added dropwise within 20 minutes. The mixture is stirred for a further 1 hour at 20 ° C. The precipitate is then washed 7 times with 100 ml of cyclohexane by decanting and stirring. The cyclohexane above the solid should be free of titanium compounds. The volume of the suspension is made up to 140 ml. The titanium content of the suspension is determined colorimetrically with H2O2. 10 ml of the suspension contain 6.1 mmol of titanium compound.

II. Polymerization of ethylene

1 l of diesel oil mil a boiling range from 140 to 200 C \ orgini. the Air is displaced by purging with pure nitrogen and the contents of the autoclave are heated to 85 C. Then a Solution of 1.0 g of aluminum triisobutyl in 50 ml of diesel oil and 0.2 ml of suspension of the supported catalyst (prepared after 3 I.) added. The polymerization is carried out at 85 ° C., while stirring, 50 g of ethylene initiated per hour. The pressure subsides in the course of the Polymerization to about 4 at. After 8 hours, the resulting polyethylene is filtered off from The dispersant is separated off and dried. 380 g of polyethylene are obtained.

Example 4
I. Representation of the supported catalyst

ll.bg Mg (OH) 2 are rubbed in a mortar with 2.7 ml (= 150 mmol) of water and added in portions at 50 ° C to 200 ml of a 1 molar TiCb (OiCiH7) 2 solution in cyclohexane with stirring and nitrogen blanketing. Stirring is continued for 5 hours at 50 ⁰ C. Then the precipitate by decanting and stirring ten times with 150 ml of cyclohexane is washed. The cyclohexane above the solid should be free of titanium compounds. The volume of the suspension is made up to 200 ml. The titanium content of the suspension is determined colorimetrically with H2O2. 10 ml of suspension contain 3.8 mmol of titanium compound.

II. Polymerization of ethylene

Under the conditions given in Example 3 II is polymerized with 0.3 ml of carrier contact suspension (prepared according to 4 I.) ethylene.

There are 8 hours of 50 g of ethylene per hour

initiated. The pressure rises to about 5 at. After filtering off the dispersant and drying 390 g of polyethylene were obtained.

Example 5
1. Representation of the supported catalyst

a) 20 g Mg (OH) 2 are added at 20 ⁰ C in 280 of a 1 molar TiCl2 (OiC3H7) 2 ml solution in cyclohexane suspended and added dropwise with stirring within 30 minutes with 5.04 ml (280 mmol) of water . The mixture is stirred at 20 ° C. for a further 2 hours. The precipitate is then washed 10 times with 200 ml of cyclohexane by decanting and stirring. The cyclohexane above the solid should be free of titanium compounds. The volume of the suspension is made up to 300 ml. The titanium content of the suspension is determined colorimetrically with H2O2. 10 ml of suspension contain 4.2 mmol of titanium compound.

b) Implementation of the supported catalyst
with ethyl aluminum sesquichloride

A solution of 10OmMoI AI _{2 (C 2} H ₅ ) JCb in 250 ml of diesel oil is added dropwise to 100 ml of the supported catalyst suspension prepared under 6 La) with exclusion of air and moisture at ⁰ ° C. over the course of 2 hours and then at 20 ° C. for 2 hours C. A blue-black precipitate forms, which is washed out 4 times with 300 ml of diesel oil each time. The volume of the suspension is made up to 100 ml.

c) Polymerization of ethylene

Under the conditions specified in Example 3 II., 0.25 ml of carrier contact suspension (prepared after 6 l.b) ethylene polymerized. 45 g of ethylene per hour are passed in for 8 hours. The pressure increases to about 4 at. After filtering off the dispersant and drying, 350 g of polyethylene are obtained.

Example 6
Gas phase polymerization of ethylene

In a horizontal 10-1 reactor with a stirrer that passes through the wall, 500 g of polyethylene ( _ipc Jc-'Y / 'en = 1.5, weight 450 g / l) are placed. The reactor is freed of air by evacuating it several times and rinsing it with an ethylene-hydrogen mixture for several hours and then heated to 85 ° C. 5.7 g of Al (C ₂ H _{5 I 3} (50 mmol) and 17 ml of suspension of the supported catalyst (prepared according to Example 11) are placed in the reactor.

400 g of ethylene per hour and sufficient hydrogen are introduced so that the hydrogen content is always 30 percent by volume during the polymerization. The pressure rises to about 9 atm in the course of the reaction. The approach is terminated after 12 hours. There are approximately 5.2 kg of polyethylene with a ij _{i / AEV} ./oWert=1,9 (measured in 0.1% Dekahydronaphthalinlösung at 135 ⁰ C).

Claims (1)

Claim: Process for the homopolymerization of ethylene and copolymerization of ethylene with up to 10% by weight of an α-olefin of the formula R-CH = CH ₂ , λνοπη R denotes a straight-chain or branched, substituted or unsubstituted alkyl radical with 1 to 10 carbon atoms, in solution, in suspension or in the gas phase, at temperatures from 20 to 150 ^° C., at pressures up to 50 atm, in the presence of a mixed catalyst consisting of a titanium-containing component (component A) and an organoaluminum compound (component B), if appropriate with regulation of the molecular weight by hydrogen, characterized in that the polymerization is carried out in the presence of a mixed catalyst, the titanium-containing component of which is carried out by reacting a titanium compound of the formula TiCI _n (OR) .. - «. in which n = 2 to 3 and R is iso-propyl, in the presence of an aliphatic, cyclophatic or aromatic hydrocarbon at temperatures from 0 to 60 ⁰ C with water in the presence of magnesium oxide and / or magnesium hydroxide, the molar ratio of titanium compound to water Is 1: 0.2 to 1: 6.