IL33680A - Catalysts for the polymerization of olefins - Google Patents

Description

Catalysts for the polymerization of olefins MONTECATINI EDISON S.p.A.

C: 31822 - 2 - 33680/2 The invention relates to the polymerisation of olefins and particularly to catalysts for the polymerization of ethylene or a mixture thereof with an -olefin and/or diolefln. The term α-olefin as Used herein excludes ethylene. More than one of each such class of co-monomers may of course be used.

The invention provides a catalyst for the polymerization of olefins which comprises a reaction product of a hydrated magnesium halide of the formula Mg£2 i nH20 Wherein X is a halogen atom (ether than fluorine) and n is a number -■©£ greater than C^wlth a halogen-containing titanium or vanadium compound under conditions such that the hydrated magnesium halide is transformed at least on the surface into an anhydrous magnesium halide, which product is activated with a hydride or organomatallic compound of a metal of Groups 1, ΪΪ or III of the Periodic System. Such catalysts have been found to show high activity.

Preferably the hydrated magnesium halide is a hydrated magnesium chloride or bromide containing from 1 to 6 and more preferably from 1 to 4 mols of water.

Examples of these halides are those of the formulae MgClg . 6H20^M 012 . 2H20»iOgCl2 . lHgO, MgBr . 6KgO and MgBr2 . H20. - 3 - 33680/2 The titanium or vanadium compounds suitable for the preparation of the catalysts include the normally liquid halogen containing titanium or vanadium compounds and also the normally solid halogen containing compounds which are soluble in solvents inert with respect to the magnesium halides. Representative examples are those of the formulae tflB 4, V014, V£ 4, 33il4{ Tl(0-1-0^)^01, $1(0-1-0^)2C12, ¾l(0-n-C4H9)2Cl2, ° ( alo-alcoholates) .

The preparation of the catalysts is preferably carried out by reacting the hydrated magnesium hallde i a stoichiometric excess of liquid or dissolved halogen containing titanium or vanadium compound preheated to its boiling temperature, and in general to a temperature greater than 100°0, and then removing the liquid phase. Another method comprises dissolving the titanium or vanadium compound in a solvent inert with respect to the hydrated magnesium hallde and/or the anhydrous hallde formed during the reaction and then reacting the hydrated magnesium hallde with the solution so obtained preheated at a temperature greater than 70 - 80°C and preferably than 100°0. In this case it is convenient to use the titanium or vanadium compound in an amount sufficient to react with the water contained in the hydrated magnesium hallde. - 4 - 33680/2 which remains on the support can vary from ver low values such as 0.01$ by weight to higher Values such as 20 ° or higher. It depends on the reaction conditions and on the percentage of water which is present in the hydrated magnesium halide. Preferably the conditions are such that the amount is from 0.1 to 10$ by weight expressed as titanium or vanadium tetrahalide.

Preferably the organometallic compound or hydride is of the formula A1(02H5)3, A1(02H5)2C1, AKiO^)^ Al(i04Hg)201, Al^H^Cl^ A1(C2H5)2H, Al(i04Hg)2Ii, LIB, CaH2, or¾tfg(C2H5)2. these the molar ratio between compoundsand the titanium or vanadium compound is not critical. For polymerizing ethylene the molar ratio Al/Ti is preferably from 50 to 1000.

Catalysts according to the invention are particularly useful for polymerizing ethylene or a mixture thereof with an a-olefin such as propylene or butene-1 and/or a diolefln, particularly with regard to the yield of polymer obtained.

They ca also be used in polymerizing a-olefins such as propylene or butene-1. The polymerization can be carried out in the liquid phase and in the presence or absence of an inert solvent or in the gaseous phase. The polymerization temperature may be from -80° to 200°P, preferably between 50° and 100°C, and the pressure atmospheric or elevated.

The molecular weight of the polymer may be regulated for example by carrying out the polymerization - 5 - 33680/2 in the presence of an alkyl halide, organometallic compound of cadmium or ¾inc, or hydrogen. Catalytic activity is only slightly influenced by the presence of the molecular weight regulators. For instance when polymerizing ethylene, it is possible to regulate the molecular weight of the polyethylene in a range of practically useful intrinsic viscosities (determined in tetralin at 135°C) from about 1.5 to 3*0 dl/g without a decrease in the polymer yield to a value below which it would be necessary to purify the polymer of catalyst residues.

The polyethylene obtained is a substantially linear and highly crystalline polymer, having a density of 0.96 g cc or more and having excellent workability, especially as far as injection moulding is concerned. The titanium content of polyethylene so prepared is generally lower than 20 parts by weight per million.

The following Examples illustrate the invention. Where not specifically indicated the percentages are by weight. The intrinsic viscosity of the polymers was measured in tetralin at 135°<3.

Example 2, Into a glass autoclave provided with a stirrer and fitted with a filter plate on the bottom there were introduced 300 cc of titanium tetrachloride. The temperature was brought up to 135°C. 70 g of magnesium chloride hexahydrate (MgCl2 . H20) free from magnesium oxychloride - 6 - 33680/2 were added. After one hour of reaction, the excess of titanium tetrachloride was removed by hot filtration.

The solid product left behind in the autoclave was repeatedly washed with boiling titanium tetrachloride and with cyclo-hexane at 80°C until the disappearance of the titanium tetrachloride from the wash liquid. The product was discharged from the autoclave and dried at 100°C under vacuum. Analysis of the dried product gave Ti - .28$, .01 = 52.7$.

X-ray analysis showed that no magnesium oxychlorlde was present and revealed the presenoe of anhydrous magnesium chloride. 50 mg of the product thus obtained were suspended in 30 cc of n-heptane and used to polymerize ethylene under the following conditions} into a stainless steel 1.8 litre autoclave purified with dry nitrogen, there were introduced 1000 cc of technical n-heptane and then 2 g of aluminium trl-iso-butyl . Thereupon the temperature was brought up to 75°C and 0.050 g of the catalyst suspended in 50 cc of n-heptane were added. Hydrogen was introduced until the pressure reached 3 atm. and then ethylene was added until the pressure increased to 10 atm. The temperature rose to about 85°C and was maintained at 80°G + 5 during the polymerization. The total pressure was kept constant by continuously feeding ethylene. After two hours the suspension wa discharged from the autoclave.

The polymer was separated b filtration and dried at 100°C under vacuum. There were obtained 355 g of polyethylene - 7 33680/2 having an intrinsic viscosity of 2.5 dl/g. The yield in polymer was 222,000 g/g of titanium.

The preparation of the catalyst of Example 1 was repeated with the variant however that the reaction took place at 100°C instead of 135 0. - Analysis of the product thus obtained gave: Ti - 5.045&, 01 * 52.5$. X-ray chloride and that no magnesium analysis showed the presence of m&ghesium/hydroxychloride (K (OH)CI) was formed. 0·059 g of the product was used to polymerize ethylene as in Example 1. There were obtained 334 g of polymer having an intrinsic viscosity of 2.7 dl/g.

The yield of polymer was 209,000 g/g titanium.

Example 3 75 g of magnesium chloride hexahydrate were dehydrated for 8 hours at 110°C in a nitrogen stream in such a way as to remove all the absorbed water and some of the water of crystallization. X-ray examination showed the presence of significant amounts of the monohydrate (MgCl2 · lHgO). 70 g of the product were reacted with titanium tetrachloride as in Example 1. The Analysis of the washed "and dried product gave a titanium content of 10.0$ and a chlorine content of 54.6 . On X-ray analysis magnesium hydroxy-chloride Mg(0H)Cl was not found to be present. 0.015 g of this product was used to polymerize ethylene as in Example 1. After 4 hours there were obtained 196 g of polymer with an intrinsic viscosity of 2.4 dl/g The yield in polymer was 151>000 g/g titanium. - 8 - 33680/2 Example 4 A catalyst prepared as in Example 1 was used in the polymerization of propylene carried out under the following conditions: 1800 cc of technical n-heptane, 4*7 g of aluminium diethyl monochloride 0.037 g of the catalyst were introduced into a 5 litre autoclave purified with dry nitrogen* 2.5 atin of propylene and 0.3 atm of hydrogen were introduced. The temperature was maintained at 70°C. The total pressure was kept constant during the polymerization by continuously feeding propylene* After 4 hours the reaction mixture was discharged from the autoclave. The polymer was separated by filtration and dried under vacuum at 100?C. There were obtained 200 g of partially crystalline polypropylene. The yield in V*. '!''·'■··■ polymer was 71»000 g/g titanium.

Example 5 7 g magnesium chloride hexahydrate were reacted with 50 cc of titanium tetrachloride as in Example 1* Analysis of the washed and dried product showed Tl = 4.55% and 01 = 6 .9 · X-ray analysis showed that the product was substantially anhydrous magnesium chloride* 0.034 g of this product was used to polymerize ethylene as in Example 1. After 6 hours there were obtained 284 g of polymer having intrinsic viscosity of 2.3 d /g. The yield in polymer was 248,000 g/g titanium. - 9 - 33680/2 Examle n 23 g of magnesium chloride dihydrate (MgCl2 . H20) were reacted with 400 cc of titanium tetrachloride as in Example 1* Analysis of the washed and dried product showed Ti = 3.75$ and 01 « 68.5$. X-ray analysis showed that the product Is substantiall anhydrous magnesium chloride. Ο.Ο425 g of this product were used to polymerize ethylene as in Example 1. After 4 hours there were obtained 452 g of polymer in a yield of 283,000 g/g titanium.

Example 7 Into the autoclave of Example 1 were Introduced 300 cc of titanium tetrachloride. Uhe temperature was brought up to 135°C. 70 g of magnesium bromide hexahydrate ( gBr2 . 6H20) were introduced. After 1 hour of heating the excess of titanium tetrachloride was removed by hot filtration. The solid product left behind in the autoclave was repeatedly washed with boiling titanium tetrachloride, and then with boiling cyclohexane until the total disappearance of the titanium tetrachloride., Analysis of the solid product dried under vacuum at 100°C showed TI » 4. 5$ and 01 and Br respectively * 53^ and 10.5$.

X-ray analysis of the product showed that it is formed of prevailing quantities of magnesium chloride. 0*041 of the product was used to polymerize ethylene as in Example 1.; After 3 hours there were obtained 545 g of polymer having an intrinsic viscosity of 2.3 dl/g. The polymer yield was 310,000 g/g titanium. - 10 - 33680/2 Example, 6 70 g of magnesium chloride monohydrate (MgCl2 , HgO) were reacted with 300 cc of titanium tetrachloride as in Example' 1. Analysis of the washed and dried product showed 3?i = 0.75S& and CI « 60.2$. X-ray analysis showed is that the product/substantially anhydrous magnesium chloride. Ho hydroxy-chloride was found. 0.031 g of this product was used to polymerize ethylene as in Example 1, After 4 hours there were obtained 159 g of polymer. ihe yield was 757»000 g/g titanium. - 11 - 33680/2

Claims (18)

1. A catalyst for the polymerization of olefins which comprises a reaction product of a hydrated magnesium halide of the formula KtgX2 . nH20 wherein X is a halogen atom (except fluorine) and n is a number greater than 0 with a halogen-containing titanium or vanadium compound under conditions such that the hydrated magnesium halide is transformed at least on the surface into an anhydrous magnesium halide, which product is activated with a hydride or organometallic compound of a metal of Groups I, II or III of the Periodic System.

2. A catalyst according to Claim 1 in which in the hydrated magnesium halide X is CI or Br and n is from 1 to 6.

3. A catalyst according to Claim 2 in which n is from 1 to 4.

4. A catalyst according to Claim 1 or Claim 2 in which the hydrated magnesium halide is of the formula MgCl2 . 6H20, gCl2 . 2H20, M Clg ... 1H20, KgBr ., 6H20 or M Br2 . H20.

5. A catalyst according to any of the preceding claims in which the halogen containing titanium or vanadium compound is a normally liquid compound. - 12 - 33680/2

6. A catalyst according to Claim 5 in which the titanium or vanadium compound is a tetrahalide or halo-alcoholate.

7. A catalyst according to any of Claims 1 to 4 in which the titanium or vanadium compound is a solid compound soluble in a solvent which is Inert with respect to the hydrated and/or anhydrous magnesium hallde.

8. A catalyst according to any of the preceding claims in which the amount of titanium or vanadium compound on the support expressed as tetrahalide is from 0.01 to 20$ by weight.

9. A catalyst for the polymerization of Olefins substantially as herein described.

10. A catalyst for the polymerization of olefins substantially as herein described in any of the Examples.

11. A method of preparing a Catalyst aeoordin to any of the precedin claims in which the hydrated magnesium hallde is reacted with a stoichiometric excess of the titanium or vanadium compound In a liquid phase preheated to its boiling temperature and then the liquid phase is removed from the reaction zone, and the reaction product is activated with the hydroxide of an organic metallic compound.

12. A method of preparing a catalyst for the polymerization of olefins substantially as herein described. - 13 - 33680/2

13. 15· A method of preparing a catalyst for the polymerization of olefins substantially as herein described in any of the Examples.

14. A catalyst prepared by a method according to any of Claims 11 to 13.

15. A process of polymerizing olefins which is carried out in the presence of a catalyst according to any of Claims 1 to 10 or 14.

16. A process of polymerizing olefins substantially as herein described.

17. · A process of polymerizing olefins substantially as herein described in any of the Examples.

18. An olefin polymer prepared by a process according to Claims 15 to 17. PC/rb