AU622321B2 - Process for the preparation of ethylene (co) polymers - Google Patents

Description

Form COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-69 COMPLETE SPECIFICATION

(ORIGINAL)

62232 1 Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art Name of Applicant HOECHST AKTIENGESELLSCHAFT Address of Applicant: 50 Bruningstrasse, D-6230 Frankfurt/Main 80, Federal Republic of Germany Actual Inventor HARTMUT LUKER and RAINER FRANKE Address for Service WATERMARK PATENT TRADEMARK ATTORNEYS.

LOCKED BAG NO. 5, HAWTHORN, VICTORIA 3122, AUSTRALIA Complete Specification for the invention entitled: PROCESS FOR THE PREPARATION OF ETHYLENE (CO)POLYMERS The following statement is a full description of this invention, including the best method of performing it known to us 1. 1: i 1e o o 0^04 o 0 o 0o 0 0 00 0 01 00 0 i 1 0 0 ia 2o I- -1 i ~i LI -Y ii~i*'l';li I HOECHST AKTIENGESELLSCHAFT HOE 89/F 148 Dr.DA/gm Description Process for the preparation of ethylene (co)polymers.

The invention relates to a process for the (co)polymerization of ethylene to give coarse polymer particles having a narrow particle size distribution and high bulk density by using catalyst particles, the support component of which has been pretreated mechanically.

Processes which provide for mechanical conditioning of 0L the starting substances for Ziegler-Natta catalysts are known.

Grinding of MgC12 or Mg(OC 2

H

5 2 with TiC14 in a bead mill S is thus known (compare DE 26 00 593). The resulting solid is employed as a catalyst for ethylene polymerization and produces a polyethylene having increased bulk density and improved Izod impact strength.

oooc Catalyst preparation from MgCl, and organomagnesium o* substances as well as silicon compounds and titanium compounds is known (compare EP 148 614). The polymeriza- 0 00 .20 tion product has a high bulk density and a large average particle diameter. As can be seen from the examples, the use of chemicals which pollute the environment, for aa example tetrahydrofuran, is often necessary. The two processes mentioned for the preparation of polymerization catalysts therefore comprise many stages and are expensive.

The use of preground magnesium alcoholate is moreover known (compare EP 223 011).

The reaction of the magnesium alcoholate with the titanium component leads to a crude product which must be purified by several washing operations using organic solvents. The ethylene (co)polymers obtained by means of Cti I il 2 this catalyst have a broad molecular weight distribution.

Nothing is known of the polymer particle size and bulk density of these polymers.

The object was to discover a simple process for the preparation of catalysts, which allows catalysts which produce a polymer having a high average and uniform particle diameter and a high bulk density to be prepared.

It has now been found that this object can be achieved if a starting compound for the catalyst is pretreated in a 10 suitable manner.

o 0 ao The invention thus relates to a process for the prepara- 000 tion of an ethylene polymer having a uniform coarse a o particle shape and high bulk density by polymerization of o o ethylene or of ethylene having up to 10% by weight, based on the total amount of monomers, of a 1-olefin of the formula R 6

-CH=CH

2 in which R 6 is a straight-chain or branched alkyl radical having 1 to 12 C atoms, in suspension, in solution or in the gas phase at a temperature of 20 to 120"C and a pressure of 2 to 60 bar, in the presence of a catalyst consisting of the reaction product o o of a magnesium alcoholate with a tetravalent titanium compound and an organoaluminum compound, which comprises carrying out the polymerization in the presence of a catalyst which consists of a) the total product from the reaction al) of a magnesium alcoholate of the formula I Mg(OR) (OR 2

(I)

in which R 1 and R 2 are identical or different and are a C 1

-C

6 -alkyl radical, the particles of which have been brought to an average particle size of 60 to 125 pm by mechanical comminution, with 3 a2) a tetravalent titanium compound of the formula II TiX (OR3 in which R 3 is a C 1

-C

6 -alkyl radical, X is a halogen atom and m is an integer from zero to 4, and a3) an organoaluminum compound of the formula III AIlR (OR (III) o in which R' and R 5 are identical or different and are o a C 1

-C

12 -alkyl radical, X is a halogen atom, n is a S. number from zero to 2 and p is a number from zero to .i0 1, in a ratio of Mg:Ti:Al of 1 0.05 to 2 0.3 to oo 5, and 0 o 0 0 0 f b) an aluminumtrialkyl having 1 to 12 C atoms in the alkyl radicals or the reaction product of an aluminumtrialkyl or aluminumdialkyl hydride with iso- 1o6C 5 prene.

ooD 00 0 To prepare the mixed catalyst component a to be employed so 0 according to the invention, a magnesium alcoholate of the formula I E:Mg(OR 1

(OR

2

(I)

4 '0 iIo is used. In this formula, R 1 and R 2 are identical or different and are an alkyl radical having 1 to 6, preferably 2 to 4, carbon atoms.

Examples are Mg(OCH 3 2 Mg(OC 2 H 2 Mg(O-i-C 3 H7) 2 Mg(O-n-CH) Mg(O-n-C 4

H,)

2 Mg(OCH 3

(OC

2

H

5 and Mg(OC 2

H

5 (O-n-CA 3 H) The simple magnesium alcoholates, such as magnesium diethylate, magnesium di-n-propylate and magnesium diisobutylate, are preferably used.

The magnesium compound is employed in a mechanically -u ^amm L~ 1 pcomminuted form. The comminution of the coarse original material is preferably effected by grinding, particularly advantageously by grinding in a bead mill, until the product has an average particle size of 60 to 125 pm, PreearAly47 noregrinding being carried out for about 10 to presferabl o t1ore a: to 25 hours,,at a temperature of -20 to 120, preferably 20 to If required, the product thus obtained can be divided into fractions each of even narrower particle size distribution by customary measures, such as, for example, by sieving.

o o o The ground magnesium alcoholate is then reacted, in an eo. inert dispersing agent, with a tetravalent titanium 0 4 0 compound of the formula II o 0 0 o 0 TiX,(OR 3 4

(II)

in which R 3 is an alkyl radical having 1 to 6, preferably 1 to 3, C atoms, X is a halogen atom, preferably chlorine, and m is zero to 4, preferably 2 to 4.

S. Examples which may be mentioned are: Ti(OC 2

H

5 )C1 3 Ti(OC 2

H

5 2

C

2 Ti(OC 2

H

5 3 C1, Ti(O-i-CH 7 3 Cl, Ti(O-i-C 3

H

7 2Cl 2 Ti(O-n-C 4

H))

3 C1, Ti(O-n-C 4

H,)

2 zC 2 Ti(O-i-

C

4

H

9 3 C1, Ti(O-i-CH 9 2 C1 2 Ti(O-n-C 4

H

9 4 and Ti(O-n-CH,) 4 TiCl 4 and Ti(o-n-C 4

H,)

2 C1 2 are preferably used.

The reaction of the magnesium alcoholate with the titanium compound is carried out at a temperature of 0 to 150, preferably at 50 to 120 0 C. The titanium compound is brought together with the magnesium alcoholate in the course of 0.5 to 20, preferably 3 to 10 hours preferably by addition of a solution of the titanium compound to a suspension of the magnesium alcoholate.

The solid formed is then reacted, without removal of the i TF ,4 5 by-products and the dispersing agent, with a halogencontaining organoaluminum compound of the formula III AlR' (OR 5

(III)

in which R and R 5 are identical or different and are an alkyl radical having 1 to 12, preferably 1 to 4, carbon atoms, X is a halogen atom, preferably chlorine, n is a number greater than zero and less than 2, preferably 1 tp 2, and p is a number greater than zero and less than 1, preferably Suitable organoaluminum compounds are Al(C 2

H

5 C1, Al(C 2

H

5 )C1 2 Al (n-C 3

H

7 2 C1, Al (n-C 3

H

7 C1 2 Al (n-C 4 H) C1 2 O Al(i-C 4

H

9 )Cl, Al(i-C 4 H,)C12, Al(n-C 4 Hg) and (OCzHs 5 C1 and o equimolar mixtures of the mono- and dihalides, the so- Socalled aluminumalkyl sesquichlorides or mixtures of monoand dihalides of different composition. Fi.om this group, Al(C 2

H

5 )Cl2 and A1 2

(C

2

H,)

3

CI

3 are preferably used.

P rex-e'oAv ]t The reaction is carried outlat a teperature of 0 to 150, SrTore preferably 50 o 120 0 C, the reaction partners being °0o° 1 morebrought together in the course of 0.5 to 20,.preferably 2 to 8 hours.

Suitable inert dispersing agents for the abovementioned reactions are aliphatic and cycloaliphatic hydrocarbons, 0 4 4 S such as butane, pentane, hexane, heptane, cyclohexane and 0 4 4 4 isooctane, and aromatic hydrocarbons, such as benzene and xylene. Gasoline and hydrogenated diesel oil fractions which have been thoroughly freed from oxyg.en, sulfur compounds and moisture can also be employed.

The magnesium alcoholate, tetravalent titanium compound and organoaluminum compound are employed in a ratio of Mg:Ti:Al of 1:0.05 to 2:0.3 to 5, preferably 1:0.2 to 1:0.4 to I The suspension thus prepared of the catalyst component a

I

-6is used directly for the polymerization without removal of the dispersing agent and the by-products.

The catalyst component b used is an aluminumtrialkyl having 1 to 12 C atoms in the alkyl radicals, such as, for example, triethylaluminum, triisobutylaluminum, triisooctylaluminum or the reaction product, known as aluminumisoprenyl, of an aluminumtrialkyl or -dialkyl hydride with isoprene. Triethylaluminum is preferred.

The polymerization is carried out in one or two stages, o0.10 preferably as suspension polymerization, in an inert oo dispersing agent. Suitable dispersing agents are the same organic solvents as have been described for the preparation of the catalyst component a. However, polymerization in the gas phase is also possible.

The polymerization temperature is 20 to 120, preferably to 90°C; the pressure is in the range from 2 to preferably 4 to 20 bar.

In the case where the reaction is carried out in two stages, the ratio of the amounts of polyolefins formed in each of the stages 1 and 2 is in the range from 30:70 to 70:30, the polymer formed in stage 1 being transferred continuously into stage 2. The final polymer mixture is stripped off continuously from stage 2.

Ethylene or ethylene containing up to 10% by weight, based on the total amount of monomers, of a 1-olefin of the formula R 6

-CH=CH

2 in which R 6 is a straight-chain or branched alkyl radical having 1 to 12, preferably 1 to C atoms is polymerized with the catalyst system used according to the invention. Examples of the 1-olefin are propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 4methyl-1-pentene. Propylene, butene and hexene are preferably employed.

In this reaction, the comonomer is preferably introduced A®i' in the first stage in which a polymer having the higher e 7 molecular weight is formed.

The total polymer from the second stage is separated off from the dispersing agent and dried in a known manner.

One advantage of the process according to the invention is the very easy preparation of the transition metal component of the catalyst. This is obtained by simply bringing together the individual components under the corresponding reaction conditions.

Washing with an inert hydrocarbon as a rule is not necessary.

o000 This also means that no wash liquor which only decomposes 00again in subsequent process steps and has to be worked up, effluent being obtained, is formed.

0000 300 Moreover, no polymer deposits occur on the kettle walls 0 -615 and in the connecting lines during prolonged continuous 00 operation, and the content of particles having a particle size of less than 100 pm in the product is significantly lower.

0 ,00 coo 0 2 The great advantage of the process according to the invention is, however, that the specifically modified O~ magnesium alcoholate allows preparation of a catalyst Gan which produces an ethylene polymer having a very high average particle diameter of 250 to 300 pm and a high bulk density of 400 to 500 g/dm 3 0 ,100 oo o The particle size distribution is highly uniform.

Another advantage results if the ground magnesium alcoholate is subjected to additional classification. The main fractions (in pm): less than 63 63 to 100 100 to 125 (11I) and greater than 125 (IV) also provide catalysts which each in themselves produce a very coarse grit-like product, the resulting polymer powder being even more uniform in particle size.

Regulation of the molecular weight of the polyolefins by j "i -8 means of hydrogen can furthermore be carried out considerably more efficiently than in conventional processes.

The examples which follow are intended to illustrate the invention.

The symbols in the examples have the following meanings: 00 o 00$4 0 1 000 6 o oo.

0110 a a oo 00 I 0415 CTAred reduced catalyst-time activity MFI 190/5 melt flow index according to DIN 53735, measured at 190"C under a load of 5 kg MFI 190/15 measured at 190"C under a MFI 190/21.6 load of 15 and 21.6 kg respectively d 50 average particle size, obtained by sieve fractionation BD bulk density, measured in accordance with DIN 53468 Example 1 Preparation of the catalyst )i a) In each case 10 to 20 dm 3 about 10.4 to 20.8 kg) of Mg(OC 2

H

5 2 were ground at -20 to 120"C for 10 to 30 hours in a bead mill which had a volume of 25 dm 3 and was charged with 500 beads of diameter 19.05 mm.

The finely divided material obtained could be separated into individual particle size fractions by sieving as required.

b) 500 mmol of Mg ethylate (57 g, particle size 63 to 100 pm) were initially introduced into 500 cm 3 of a hydrogenated diesel oil fraction in a 2 dm 3 stirred vessel with exclusion of air and moisture. 500 cm 3 of a 0.2 molar solution of TiCl 4 were added to the diesel oil fraction at a temperature of 100 0 C in the course of 2 hours, while stirring and covering with a layer of argon. 500 mmol of AlClI(C 2 Hs) in 1000 cm 3 of diesel oil were then added dropwise in the course of 2 hours. The batch was

I"

9 subsequently stirred for a further 2 hours. The reaction batch became brownish in color and contained 0.065 mol of Ti3+/dm 3 One portion of this suspension was diluted with the diesel oil fraction to a Ti concentration of 0.01 mmol/dm 3 Example 2 Ethylene polymerization o -10 o o 3 0 o 0 o 0 0 o 0 0 00 0' 0 0 dr) 0.02 mmol of catalyst according to Example 1 were initially introduced into 1500 cm 3 of diesel oil with 3 mmol of triethylaluminum in a 2 dm 3 pressure reactor. After forcing in 3.15 bar of H2 and 3.85 bar of ethylene, polymerization was carried out at 85"C for 2 hours.

Result Yield: 140 g CTAred.: 909 g/mmol of Ti.h.bar MFI 190/5: 30 g/10 minutes MFI 190/15: 151 g/10 minutes ds 5 240 pm Portion <100 pm: 1% BD: 0.33 kg/dm 3 Example 3

OI

oo o oei s o The procedure was as in Example 2, but an Mg ethylate of particle class 100-125 pm was used in the preparation of the catalyst. This catalyst was used for the polymerization.

Polymerization result: Yield: 170 g CTAred.: 1120 g/mmol of Ti.h.bar MFI 190/5: 34 g/10 minutes MFI 190/15: 167 g/10 minutes do 0 236 minutes Portion <100 pm: 1% BD: 0.34 kg/dm 3 i 10 Example 4 A non-sieved ground Mg ethylate having an average particle diameter of 60 pm was used to prepare the catalyst.

A polymerization was carried out in accordance with Example 2 using the catalyst thus prepared.

Polymerization result: Yield: CTAred.: 1025 g/mmol of Ti.h.bar .,10 MFI 190/5: 31.1 g/10 minutes 0 0 MFI 190/15: 147 g/10 minutes ds0: 210 pm Portion <100 pm: 2% SBD: 0.345 kg/dm o 0 o o 0 0 000 0 Comparison Example A The procedure was initially as in Example Ib, using a non-ground Mg ethylate having a d 50 of 540 pm.

The procedure was then as in Example 2.

Polymerization result: Yield: 162 g CTAed.: 1056 g/mmol of Ti-h-bar MFI 190/5: 17 g/10 minutes MFI 190/21.6: 166 g/10 minutes o ds 0 142 pm Portion <100 pm BD: 0.33 kg/dm 3 Example 1000 mmol of Mg ethylate (114 g) of particle size class 63 to 100 pm were initially introduced into 500 cm 3 of a hydrogenated diesel oil fraction in a 2 dm 3 stirred vessel, with exclusion of air and moisture. 2.2 mol of TiC14 in 1000 cm 3 of diesel oil were added at a ,1I lc 11 temperature of 100°C in the course of 5 hours, while stirring and covering with a layer of argon.

After the addition, the white reaction product was kept at 100 0 C for 12 hours. The composition of the catalyst component thus obtained was Mg:Ti:Cl 1:0.11:2.05.

10 0 0D 0 0 o o o oo o a S0 1 5 o o 0 0 0 af 0 This catalyst component was used for polymerization under the conditions of Example 2, but the amount of catalyst employed was 0.015 mmol, based on titanium, and 3.5 mmol of triisobutylaluminum was used as the activator. The result of the polymerization was: Yield: 134 g CTAred.: 1163 g/mmol of Ti-h.bar MFI 190/5: 3.65 g/10 minutes MFI 190/21.6: 41.4 g/10 minutes ds 5 233 pm Portion <100 pm: 1% BD: 0.31 kg/dm 3 s: F" 0009 0 0 000 00 9 0 09 0 Q9 .,20 o o.2 6 oo? Example 6 The procedure was as in Example 5, Mg ethylate of particle class 100-125 pm being employed to prepare the catalyst.

Polymerization of ethylene: Yield: 91 g CTAed.: 790 g/mmol of Ti.h.bar MFI 190/5: 2.77 g/10 minutes MFI 190/15: 17.2 g/10 minutes dso: 232 pm Portion <100 pm: 1% BD: 0.3 kg/dm 3 Example 7 The procedure was as in Example 5, ground non-sieved Mg TiXm(0R 3 4 -m (I I) /2

I.

4 1 0 12 ethylate having an average particle size of 60 um being employed to prepare the catalyst.

The result of the polymerization was: Yield: 143 g CTAedj: 1241 g/Mniol Of Ti-h-bar MFI 190/5: 3.8 g/10 minutes MJFI 190/21.6: 44.4 g/10 minutes d 50 248 Am Portion <100 pm: 1% BD: 0.32 kg /dIM 3 *tat to4 0 8 4 oo*

A

I

'I

Claims (3)

1. A process for the preparation of an ethylene polymer having a uniform coarse particle shape and high bulk density comprising polymerization of ethylene or of ethylene having up to 10% by weight, based on the total amount of monomers, of a 1- olefin of the formula R6-CH=CH 2 in which R6 is a straight-chain or branched alkyl radical having 1 to 12 C atoms, in suspension, in solution or in the gas phase at a temperature of 20 to 12000C and a pressure of 2 to 60 bar, in the presence of a catalyst consisting of a) the total product from the reaction of al) a magnesium alcoholate of the formula I Mg(OR1)(OR2) (I) o: o Sin which RI and R2 are identical or different and are a C 1 -C-alkyl radical, the particles of which have been brought to an average particle size of 60 to 125 prm a2) a tetravalent titanium compound of the formula II TiXm(OR 3 )4-m (II) in which R 3 is a C 1 -Cs-alkyl radical, X is a halogen atom and m is an integer from Szero to 4, in an inert dispersing agent at a temperature of 0 to 1500C for 0.5 to hours and then of the product of the reaction of al) and a2) with a3) an organoaluminum compound of the formula III 4 5 (III) A1R n (OR X3-n-p in which R4 and Rs are identical or different and are a C 1 -C 1 2 -alkyl radical, X is a halogen atom, n is a number from zero to 2 and p is a number from zero to 1, in a ratio of Mg:Ti:Al of 1 0.05 to 2 0.3 to 5, and then of the total reaction product a) with b) an aluminumtrialkyl having 1 to 12 C atoms in the alkyl radicals or the reaction Sproduct of an aluminumtrialkyl or aluminumdialkyl hydride with isoprene. bU±LVt:11IL6Z .LILU t!I.J1Y±M11t kU)jpO.yII-Lb U1LC1J.11WU Li)' 1LL=C1JaW 9, 9 I

2. using to The process as claimed in claim 1, wherein a catalyst which has been prepared a ground magnesium alcoholate having a particle size distribution narrower than 125 gm. ne.s l

3. The process as claimed in claim 2, wherein a 1 i~qgnsium alcoholate ground in a bead mill is used. DTDthis 12th day of December, 1991 HOECHST AKTIENGESELLSCHAFT Cl *4* o a 44,4,. 9 9 00*0 a a a 00 CO 0$ 04 04~ 9 4 0 94*,. 00 a o op a. WATERMARK PATENT TRADEMARK ATTORNEYS THE ATRIUM 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA AU005507090.WPC