GB2160535A

GB2160535A - Zirconium and/or hafnium based catalyst for the polymerization of unsaturated compounds

Info

Publication number: GB2160535A
Application number: GB08515470A
Authority: GB
Inventors: Margherita Corbellini; Angelo Moalli
Original assignee: ECP Enichem Polimeri SRL
Current assignee: ECP Enichem Polimeri SRL
Priority date: 1984-06-22
Filing date: 1985-06-19
Publication date: 1985-12-24
Also published as: NL8501815A; LU85968A1; ZA854595B; DK279185D0; NO852451L; GB8515470D0; ES544981A0; PT80685B; DE3522295A1; BE902730A; IT8421559A1; RO92339B; IT8421559A0; JPS6114202A; GR851522B; ES8609372A1; IL75590A0; FR2566412A1; SE8503033D0; IT1176299B

Abstract

A catalyst comprising zirconium and/or hafnium is prepared by the following steps: (a) vaporization in vacuo of magnesium and reaction of the thus obtained vapour with a compound of quadrivalent titanium in the presence of a halogen donor and of a compound of zirconium and/or hafnium; (b) thermal treatment of a mixture comprising an alcohol of the formula ROH, wherein R is an aliphatic, linear or branched chain, containing from 1 to 10 carbon atoms, optionally substituted by one or more aromatic groups, and the solution prepared in step (a); (c) thermal treatment of a mixture comprising an organometallic aluminium compound of the formula AIR'3-yXy wherein R' is a hydrocarbon radical, X is a halogen atom and y is a number of from 0 to 2 inclusive, such that 1 </= halogen/Al </= 2, and the solution prepared in step (c). The catalyst is used for the polymerisation of unsaturated compounds.

Description

SPECIFICATION Zirconium and/or hafnium based catalyst for the polymerization of unsaturated compounds The present invention relates to a process for the homopolymerization or the copolymerization of a-olefins, comprehensive of ethylene, characterized by the use of a novel catalytic system based on a catalyst on the basis of titanium, magnesium, zirconium or hafnium.The catalytic system resulting from the association of such a catalyst with two further components, as specified hereinunder, has a so peculiar and surprising behaviour, as to result efficacious, among others, in the preparation of homopolymers having a broad molecular weight distribution, or of copolymers having also a high environmental stress cracking resistance (E.S.C.R,), property required for particular items, such as e.g. bottles, an addition to other characteristics, such as a so broad molecular weight distribution, as to render the products particularly suitable to the manufacturing of films or of tubes, as it will be better clarified hereinunder.

The polymerization of ethylene by means of titanium-based catalysts is largely described in Patent literature. For instance, in the UK Patent No 2068389 granted on June 1984 there is disclosed a process of homopolymerization (or of copolymerization) of unsaturated compounds, in particular of ethylene and higher a-olefins, to yield homopolymers (or copolymers) having a broad distribution of molecularweights (8 < Mw/Mn c 12) suitable to be formed by the blow-moulding technique, but not particularly suitable for items such as films or tubes.Such a process uses as the catalyst, in combination with an aluminium organometallic compound, a chemical composition on the basis of titanium trihalogenide of the following formula: Ti X3 mM'Yn q MW'p. cAl Y"3.sRs wherein Xis a halogen ion and m, q, c, M', M", Y, Y', Y", n, p, s, R have the meaning reported in the specification of the hereinabove mentioned Patent Application.

In the UK Patent No 2103226 granted on March 1985 a process is on the contrary disclosed for the polymerization and the copolymerization of a-olefins (including ethylene) also in the presence of conjugated diolefins, and in particular for the polymerization of ethylene with 1,3-butadiene, based on the use of a multi-component catalytic system, wherein one of such components contains titanium and magnesium, the polymers obtained by this process have anyway in a narrow molecular weight distribution (3 < Mw/Mn < 5).

We have now found, what is the object of the present invention, that it is possible to obtain a catalyst particularly suitable as the catalytic component in the homopolymerization of ethylene, or in the copolymerization of ethylene with o-olefins.

The catalyst being the object of the present invention is obtained by means of a method comprising the following steps: a) vaporization in vacuo of magnesium and reaction of the vapours obtained with a compound of quadrivalent titanium in the presence of a halogen atom donor compound and of a compound of zirconium and/or hafnium.

b) thermal treatment of the mixture obtained by means of the addition of an alcohol of formula ROH, wherein R is an aliphatic linear or branched chain containing from 1 to 10 carbon atoms, possibly substituted with aromatic groups, to the previously prepared cold solution.

c) thermal treatment of the mixture obtained by means of the addition of at least one organometallic compound of aluminum of formula AlR'3.yXy, wherein R' represents a hydrocarbon radical, X represents a halogen and Y is a number equal to or comprised within the range of from 0 to 2, such that 1 < Halogenide/Al < 2, to the previously prepared solution.

The vaporization of step a is carried out under pressures comprised between or equal to 100 and 104 tory, at a temperature ranging from 300 to 600 C. The reaction of the vapours thus obtained with the titanium compound in the presence of the halogen-donor is carried out at low temperature, usually at temperatures between or equal to -80 and + 20"C. To the purpose of maintaining the reaction mixture in the fluid condition, to the cooled reactants, generally within the range of from - 100 to + 10 C, an inert hydrocarbon diluent such as e.g. n.heptane or n.hexane may be added.

The thermal treatment of step b occurs at temperatures equal to or comprised within the range of from 50 to 100 C, for times equal to or comprised within the range of from 60 ' to 180 ', under stirring.

The organometallic compound of aluminium is added in the step c as such, or as a hydrocarbon solution, the preferred compound being Al2EtCl3.

The thermal treatment of stepc is carried out at a temperature equal to, or comprised within the range of from 80 to 100"C under stirring. The following molar ratios are used: 0.3% Mg/ROH < 2 5 < Mg/Ti 20 2Mg/Zr < -= 5 1 < Mg/Hf < 10 The compound of zirconium or of hafnium, which may be also introduced in the second step, is selected among the halogenides and the alkoxides, and in particular zirconium tetraalkoxide, zirconium tetrachloride, hafnium tetrachloride is used.

The alcohol ROH may be a primary, secondary or tertiary alcohol, wherein R is an aliphatic, linear or branched chain, containing from 1 to 10 carbon atoms, possibly substituted with aromatic groups, but preferably butyl alcohol, amyl alcohol, isoamyl alcohol, benzyl alcohol is used.

As the halogen donor, the organic halogenides can be used, in particular those of formula CmH2m+2-xXxf wherein X = Cl, Br, m represents a number equal to or comprised within the range of from 1 to 18 andx is a number equal to or comprised within the range of from 1 to 4, and in this case they may also constitute the said diluent medium, or inorganic halogenides can be used of elements in a high valence state, but capable of existing in at least two oxidation states, such as Snow4, SbCI5, POOl3, Viol4.

As for the titanium compound, this can be selected within a broad range of products such as, e.g.

trihalogenhides and tetrahalogenides of titanium, titanium tetraalcoxides and halogeno-alkoxides, titanium tetrabenzyl and halogeno-benzyl derivatives, titanium tetraallyl and halogeno allyls, titanium amides and amido-halogenides, chelates of titanium, and so on. Their use resulted to be particularly efficacious, and it is a second object of the present invention, as components of catalytic systems in the homolymerization of ethylene or in the copolymerization of ethylene with a-olefins.

We have indeed found that it is possible to prepare polymers or copolymers of ethylene by causing the polymerization to occur in the presence of a system constituted by a derivative of aluminum of formula AlRpX3.p, with R being a hydrocarbon residue, X halogen and p equal to or comprised within the range of from 1 to 3, and by a catalyst based on zirconium or hafnium as hereinabove defined.

The a-olefins to be copolymerized with ethylene are preferably butene-1, propene, hexene-1, octene-1.

Said composition can be directly used in the polymerization, as obtained from the hereinabove disclosed preparation method, without any filtration or separation. The polymerization is carried out in its turn in the presence of a hydrocarbon solvent which may of course be the same as the diluent used for the preparation of titanium derivative, at temperatures ranging from 20 to 200 C, and under pressures ranging from 1 to 60 atmospheres.

Alternatively, the polymerization may be accomplished by directly delivering the momomer or the monomers in the gaseous state, on the catalytic system. Polymers and copolymers of ethylene are obtained with high yields, with broad molecular weight distribution, as it appears from the values of Mw/Mn obtained by gel permeation chromatography (G.P.C.) comprised within the range of from 12 to 20.

Such polymers are particulary suitable to the extrusion and blow-moulding technology, in particular for film production.

Thanks to their high environmental stress cracking resistance, the products are particularly suitable for some applications such as containers for detergents and large containers.

Example 1 Preparation of catalytic Component The first preparation step is carried out in a rotary flask in whose center a spirally-wound tungsten filament is placed, which is connected to an electrical energy feeder.

into the flask about 500 cm3 of anhydrous heptane, 0.60cm3 (5.4 mmole) of TiCI4, 6 g (25.7 mmole) of ZrOl4 and 25 cm3 (237mmole) of chlorobutane are charged under a nitrogen atmosphere.

Around the tungsten spiral 3 g of mg (125 mgatoms) is wound. The flask is cooled to -70 C, the vacuum up to 10-2 torr is applied, and the spiral is heated so as to vaporize the magnesium.

After 20', nitrogen is introduced into the flask and in the second step of the cool suspension 7.43cm3 of isoamyl alcohol are added under stirring. The flask is brought back to room temperature and the reaction mass is then heated at boiling temperature for 2 hours, a brown-coloured suspension being obtained.

In the third preparation step, to the previously obtained suspension 108 mmole of Al2Et3CI3 are added, and the whole reaction mass is heated at boiling temperature for 3 hours. The colour of the suspension turns into green-blue.

The catalyst thus obtained is washed with heptane and has the following elemental composition: Ti = 1.55% Mg = 14.65% Zr = 14.34% Cl = 69.4% Example 2 Polymerization Into a 5 1 autoclave, free from air and moisture and provided with a magnetic-keeper stirrer, 2 1 of anhydrous and deaerated n.heptane and 8 mmole of Al(iso.bu)3 are charged. The temperature is raised to 80"C and then into the flask are charged, in the order shown: 5.6 bars of H2, 8 g of butene-1, an amount of catalyst suspension prepared according to Example No 1 equivalent to 0.0212 mgat of titanium, and ethylene up to a total pressure of 9.4 bars. The ethylene feed into the autoclave is continued for 2 hours, while maintaining the pressure at a constant value. After this period of time, the reaction is stopped and the autoclave is vented.An amount of 359 g of polymer is obtained, equivalent to 355,000 g per g of metal titanium. The characteristics of the product are: - melt flow index under a load of 2.16kg (MFl216 ASTM Standard 1238/E) = 0.35 g/10'.

- Shear sensitivity (S.S., MF121.6/MF12.16) = 101.

- density (d, ASTM Standard D 1505) = 0.9548 kg/dm3.

- shear rate (y,, ASTM Standard D 1703) = 1000 s~1.

-Environmental stress cracking (ESC, ASTM Standard D 1693) = 220 hours.

-MLv/Mn = 14.5 (G.P.C.) Example 3 Preparation of Catalytic Component The preparation of the catalyst is carried out as disclosed in Example 1. Into the flask 300 cm3 of anhydrous heptane, 0.6 cm3 of TICL4 (5.4 mmole), 6 g of ZrCI4 (25.7 mmole) and 26 cm3 of 1-chlorohexane (790 mmole) are loaded under nitrogen atmosphere. Around the tungsten spiral, 2.45 g of magnesium (100 mgatoms) are wound, and the vaporization is carried out as in Example 1.

To the cold suspension 7.5 cm3 of butyl alcohol are added under stirring. In the third separation step, to the suspension 100 mmole of Al2Et3Cl3 are added and the suspension is heated for 3 hours. The product is washed with heptane, and after having been dried it has the following elemental compositions: Ti = 1.78% Mg = 13.36% Zr = 16.38% Cl = 68.15% Example 4 Polymerization The equipment oand the same operating way as described in Examples 2 are used.

At 80"C: 5.6 bars of H2, 6 g of butene-1, an amount of catalyst suspension prepared according to Example 3 equivalent to 0.02 mgat of titanium and ethylene up to a total pressure of 9.4 bars are added. After two hours of polymerization, 320, g of polymer, equal to a yield of 333,000 g/g of titanium are obtained. The characteristics of the product are the following: MFl216= 169/10' S.S = 95 d = 0.9565 kg/dm3 ,'c=850s1 ESC = 500 hours.

Mw/Mn = 16.

Example 5 Polymerization The polymerization is carried out as in Example 4, with the exception of the comonomer which is in this case propene in an amount of 5 g. The product obtained, 360 g, has the following characteristics: MFl2.16 = 0.32 g/10' S.S = 105 d = 0.9572 kg/dm3 zz = 1800 so1 ESC = 100 hours Mw/Mn = 13.5 Example 6 Preparation of Catalytic Component The preparation of the catalyst is carried out by loading into the flask under a nitrogen atmosphere, 300 cm3 of anhydrous heptane, 0.48 cm3 of TiC14 (4.3 mmole), 3.2 cm3 of chlorobutane (30 mmole). Around the tungsten spiral 0.6 g of magnesium wire (25 mgat) are wound and are vaporized as in Example 1.To the cold suspension, 4.6 g of HfC14 (14.4 mmole) and 5.2 cm3 of n.butanol (57.6 mmole) are added under stirring. In the third preparation step, to the suspension 42.5 mmole of Al2Et3Cl3 are added and the suspension is heated at boiling temperature for 3 hours.

The product is washed with heptane and after drying it shows the following elemental composition: Ti = 2.7% Mg = 7.66% Hf = 34.2% Cl = 55.3%.

Example 7 Polymerization The equipment and the reaction procedures as of Example 2 are used. Six bars of H2, 6 g of butene-1, an amount of catalyst suspension obtained according to Example 6 equivalent to 0.0374 mgat of titanium, and ethylene up to a total pressure of 9.4 bars are loaded.

After two hours of polymerization, 206 g of polymer, equal to a yield of 115.000 g/g of titanium are obtained.

The characteristics of the product are: MFl2.16 = 0.219/10' S.S = 145 d = 0.9579 kg/dm3 zC = 750 s 1 ETC = 500 hours Mw/Mn = 15.

Claims

1. A method for the preparation of a catalyst comprising zirconium and/or hafnium, which method comprises the following steps: (a) vaporization in vacuo of magnesium and reaction of the thus obtained vapour with a compound of quadrivalenttitanium in the presence of a halogen donor and of a compound of zirconium and/or hafnium; (b) thermal treatment of a mixture comprising an alcohol of the formula ROH, wherein R is an aliphatic, linear or branched chain, containing from 1 to 10 carbon atoms, optionally substituted by one or more aromatic groups, and the solution prepared in step (a);; (c) thermal treatment of a mixture comprising an organometallic aluminium compound of the formula AlR'3 yXy wherein R' is a hydrocarbon radical, Xis a halogen atom and yisa number of from 0 to 2 inclusive, such that 1 s halogen/Al s 2, and the solution prepared in the step (c).

2. A method according to claim 1, wherein the vaporization of magnesium is carried out under a pressure of from lotto lOAtorrinclusive.

3. A method according to claim 1 or 2, wherein the vaporization of magnesium is carried out at a temperature of from 300 to 600"C inclusive.

4. A method according to any of claims 1 to 3, wherein the reaction between the vapour of magnesium, the compound of quadrivalent titanium, the halogen donor and the compound of zirconium and/or hafnium is carried out at a temperature of from -80 to 20"C inclusive.

5. A method according to any of claims 1 to 4, wherein the thermal treatment in step (b) is carried out at a temperature of from 50 to 10000 inclusive.

6. A method according to any of claims 1 to 5, wherein the thermal treatment in step (b) is carried out for a time of from 60 to 180 minutes inclusive.

7. A method according to any of claims 1 to 6, wherein the thermal treatment in step (c) is carried out at a temperature of from 80 to 100"C inclusive.

8. A method according to any of claims 1 to 7, wherein the process is carried out using one or more of the following molar ratios: 0.3 s Mg/ROH s 2.0 5 sMg/Tis20 2 SMg/Zrs5 1 sMg/Hfs10

9. A method according to any of claims 1 to 8, wherein the organometallic aluminium compound is Al2Et3CI3

10. A method according to any of claims 1 to 9, wherein the compound of zirconium and/or hafnium is a halide or alkoxide thereof.

11. A method according to claim 10, wherein the compound of zirconium and/or hafnium is a zirconium tetraalkoxide, zirconium tetrachloride or hafnium tetrachloride.

12. A method according to any of claims 1 to 11, wherein the alcohol ROH is butyl alcohol, amyl alcohol, isoamyl alcohol or benzyl alcohol.

13. A method according to any of claims 1 to 12, wherein the halogen donor is an organic halide.

14. A method according to claim 13, wherein the halogen donor has the general formula CmH2m+2-xXX wherein Xis Cl or Br, m is a number of from 1 to 18 inclusive, and xis a number of from 1 to 4 inclusive.

15. A method according to any of claims 1 to 12, wherein the halogen donor is the higher of highest valency inorganic halide of an element capable of existing in at least two valency states.

16. A method according to claim 15, wherein the halogen donor is Snow4, SbCls, POOl5 or Viol4.

17. A method according to any of claims 1 to 16, wherein the compound of titanium is a titanium trihalide, a titanium tetrahalide, a titanium tetraalkoxide, a titanium haloalkoxide, titanium tetrabenzyl, a titanium halobenzyl derivative, titanium tetraallyl, a titanium haloallyl, a titanium amide, a titanium amido halide or a chelate of titanium.

18. A method according to claim 1, substantially as hereinbefore described in any of the foregoing Examples 1,3 and 6.

19. A catalyst when prepared by a process according to any of claims 1 to 18.

20. A process for the homopolymerization of ethylene or for the copolymerization of ethylene with one or more a-olefins, which comprises contacting the ethylene and optionally the a-olefin(s) with a catalytic system comprising(a) a derivative of aluminium of the formula Al Bp X3.p wherein R is a hydrocarbon residue, Xis a halogen atom and p is from 1 to 3 inclusive, and (b) a catalyst according to claim 19.

21. A process according to claim 20, substantially as described in any of the foregoing Examples 2,4,5 and 7.

22. A homopolymer of ethylene, or a copolymer of ethylene with one or more oc-olefins, when prepared by a process according to claim 20 or 21.