IE43671B1 - Olefin polymerisation catalyst components, catalysts comprising said components and olefin polymerisation process - Google Patents

Description

This invention relates to the polymerisation of olefins, and particularly to catalysts and catalyst components useful therein.

Recently, new highly-active supported transition metal compound catalyst components based upon the use of magnesium compounds have become available for the commercial production of polyolefins,, in particular, polyethylene. For example, German Offenlegungsschrift 2,123,356 teaches polymerization of ethylene and its mixtures with a catalyst component made from a magnesium dialkoxide, a titanium (IV) compound and an alkylaluminum halide.

Such catalyst components require a cocatalyst (promoter) such as an alkylaluminum compound when used for polymerization.

We have now developed a treatment which results in the production of catalyst components which when used in polymerization result in fewer product fines.

Thus according to one aspect of the invention there is provided a process for treating a solid olefin-polymerization catalyst component containing from 0.1 to 15 wt.%, calculated as the metal, of a transition metal-containing material and formed from: (1) a magnesium compound; (2) a transition metai-containing material which is a titanium (IV) alkoxide, alkoxychloride, or chloride; or a mixture thereof with a vanadium (V) alkoxide,alkoxychloride, or chloride; or with a zirconium (VI) alkoxide, alkxoychloride, or chloride wherein each alkoxy group contains 1-6 carbon atoms; and (3) an alkylaluminum compound to reduce the fines content of polymerized product formed by polymerizing one or more olefins in the presence of said soild catalyst component and added promoter, which process comprises contacting said catalyst component with at least one mole of - 2 43671 hydrogen chloride per mol of alkylaluminum compound.

The invention further provides an olefin polymerization catalyst component useful in the preparation of polyolefins containing reduced levels of fines comprising a solid prepared from: (a) the reaction product of (l) a magnesium compound; (2) a transition metal-containing material which is a titanium (XV) alkoxide, alkoxychloride, or chloride; or a mixture thereof with a vanadium (V) alkoxide, alkoxychloride, or chloride; or with a zirconium (XV) alkoxide, alkoxychloride, or chloride; and (3) a alkylaluminum compound wherein each alkoxy or alkyl group contains 1-6 carbon atoms, using a mol ratio of said alkylaluminum compound to total mols of said magnesium compound and transition metal-containing material between 0.2:1 and 10:1; and (b) at least one mol of hydrogen chloride per mol of said alkylaluminum compound used, said solid containing from 0.1 to 15 wt.7., calculated as the metal, of said transition metal-containing material.

I Olefin polymerization catalyst, especially such catalyst suitable for polymerizing ethylene or a mixture thereof with up to 20 mol 7, oi a polymerizable Cg to Cg olefin to produce a polymeric product containing reduced levels of fines, may be formed from the above-defined catalyst component and a promoter which is a trialkylaluminum, a dialkylaluminum hydride, or a dialkylaluminum chloride and forms a further aspect of the invention.

As indicated, at least three materials are employed in making the catalyst component. The first material is a magnesium compound such as, for example, a magnesium alkoxide, magnesium oxide, magnesium chloride or magnesium acetate. More preferably, a lower alkyl, magnesium dialkoxide having an alkyl radical of from one - 3 to six carbon atoms is used, and, most preferably, magnesium diethoxide is the first material.

The second material is preferably a transition-metal-containing material which at least contains a titanium (IV) alkoxide, alkoxychloride or chloride any alkoxy groups of which contain 1-6 carbon atoms. More preferably, it is a transition-metal-containing material which at least contains a titanium (IV) alkoxide or alkoxychloride. The second material can also contain a vanadium (V) alkoxide, alkoxychloride, or chloride, or a zirconium (IV) alkoxide alkoxychloride or chloride.

The third material is preferably a lower alkyl, alkylaluminum compound such as a trialkyl, a dialkylaluminum chloride Or an alkylaluminum dichloride. More preferably, it is a lower alkyl, alkylaluminium dichloride in which the alkyl group contains from one to six carbon atoms. Most preferably, the third material is ethylaluminum dichloride.

At least two modes of preparation of the solid catalyst component give good results. The first is to react, preferably in the presence of an inert diluent, the magnesium compound and the -θ transition-metal-containing material and thereafter react the product with the alkylaluminum compound. The second is to react the magnesium compound, the transition-metal-containing material and the alkylaluminum compound together, preferably in the presence of inert diluent. The solid product in each case is thereafter treated with the hydrogen chloride.

The relative amounts of magnesium compound and transition metal compound used to make up the solid catalyst component are preferably 0.1 to 3 mols of the transition-metal compound per mol of magnesium compound used, and, more preferably, 0.5 to 1.5 mols of transition-metal-containing material per mol of magnesium compound used. The relative amount of the alkylaluminum compound preferably - 4 43671 used in the catalyst component preparation is 0.2 to 10 mols of alkylaluminum compound per total mols of magnesium and transition-metal containing-material More preferably, this ratio varies between 0.5 and 5 mols of alkylaluminum compound per total mols of magnesium and transition metal containing material employed.

The total amount of hydrogen chloride used to prepare the treated catalyst component depends upon the amount of alkylaluminum compound used to prepare such component and is preferably in the range between an effective amount to six mols for each mole of aklylaluminum compound used to prepare the catalyst component, and more preferably, between an effective amount and four mols for each mol of alkylaluminum compound used to prepare the catalyst component. Preferably, the mol ratio of hydrogen chloride to alkylaluminum compound is greater than one.

The hydrogen chloride is generally added to the catalyst compound suspended in an inert liquid diluent after insuring that the agent and diluent are dry and substantially free of polar compounds. It is convenient to bubble gaseous hydrogen chloride through the suspension with stirring. However, other methods of treatment such as passing hydrogen chloride over the surface of the solid catalyst component can be used.

Preferably, each reaction step involved in making the.solid catalyst component is carried out by heating in the temperature range from above ambient to 150°C. and, more preferably, in the range of from 30°C. to 120°C. Generally, reactions involving an alkylaluminum compound are carried out at the lower end of the above ranges whereas reactions involving alkoxides, particularly Ti(OR)^ compounds, are carried out at the upper end of the above ranges.

In the step wherein the catalyst component is treated with the hydrogen chloride, the temperature of reaction is preferably in the range from ambient to 70°C and, more preferably, in the range from ambient to 50°C. - 5 43671 It is generally efficacious and preferred to carry out each preparative step by heating the reactants in an inert, liquid diluent at slow reflux. However, where the transition-metalcontaining material is reacted with the magnesium compound in a j separate step, such materials if stable and liquid can be used neat. By inert liquid diluent is meant a diluent which at least partially dissolves some .of the reactants and is substantially unreactive with the reactants and the product at the reaction temperature. Hydrocarbons, aromatic or aliphatic, such as benzene or heptane and their halo derivatives are excellent for this purpose if they can be conveniently handled at the reaction temperature. Aliphatic hydrocarbons such as a hexane, an octane or a decane are preferred. It is important, for best results, that the inert liquid diluent chosen is purified prior to use from traces of moisture, oxygen, and traces of polar organic substances by, for example, percolating the diluent through silica gel or molecular sieves.

Preferably, each preparation step is allowed to continue for thirty minutes to forty eight hours and, more preferably, two hours to about twenty-four hours. The catalyst component treatment step ) with the chloride-affording-agent is faster and takes only a few minutes even at ambient temperature.

The amount of transition metal combined in the treatable solid catalyst components is relatively small being in the range of 0.1 to 15 weight percent, calculated as the metal, of the support weight. > More preferably, it is between 0.5 to 10 weight percent. Other things being equal, the more transition metal compound combined with the support material, the more active the supported catalyst becomes. Too much, however, can he wasteful of the transition-metal-containing material and also can lead to decreased yields. - 6 43 6 71 Use of the treated solid catalyst component for the polymerization of olefins is accompanied by the use of a promoter which is preferably an alkylaluminum compound. More preferably, it is a lower alkyl, trialkylaluminum, a dialkylaluminum hydride or a dialkylaluminum chloride and, most preferably, a lower alkyl, trialkylaluminum is the promoter used. By lower alkyl is meant an alkyl group containing from one to six carbon atoms.

For polymerizations in which polymer particles are formed the total amount of organoaluminum promoter used depends upon whether the promoter is mixed with the polymerization diluent as well as the treated catalyst component. For preferable results employing a process using a diluent, the ratio of total millimols of organoaluminum compound used to grams of supported catalyst component should be at least two to one. More preferably, it is at least ten to one and, most preferably, it is at least twentyfive to one. This ratio depends upon polymerization temperature somewhat, increasing as polymerization temperature decreases and also upon diluent purity and the amount of diluent used. For vapor phase polymerization the amount of alkylaluminum compound required can be substantially less. - 7 43671 I The treated catalyst component described above can he used in the particle form variation, preferably in the temperature· range from , above ambient to 130θϋ and, more preferably in the temperature range 40°C. to llO^C. The treated catalyst component may be used also in an essentially media-less process wherein the olefin is polymerized directly from che vapor or liquid phase. The polymerization temperature using an essentially solventless process should be large enough to give an adequate polymerization rate but not too large to raise the pressure above that which is normally used in this type of process, i.e., several hundred p.s.i.g. In vapor state polymerizations wherein supported catalyst component, alkylaluminum promoter, monomer and quench liquid, if used, are Important components, the preferable temperature range is from 0°C. to 130°C< and, more preferably, °C to 120°C.

Whereas the preferred olefin is ethylene, the treatment can he useful in the preparation of other C to Co . olefins as well. o Such Cj to Cg olefins are, e.g., propene, 1-butene, 1-pentene, ή-methylpentene-l, or Styrene, or a polymerizable diolefin such as butadiene, or isoprene. Obviously, the treated solid catalyst components can be used also for the polymerization of mixtures of such olefins.

It is of particular importance, for best results, that the olefin, for example ethylene, be substantially free of catalyst poisons. Thus, it is preferred to use polymerization grade ethylene and to pass it through a molecular sieve prior to use to remove the remaining traces of moisture, oxygen, carbon dioxide and polar organic compounds.

I'he polymerization diluent employed ln a particle form process can be an aliphatic alkane or cycloalkane such as isohutane, pentane, hexane, heptane or cyclohexane or a hydrogenated aromatic compound such as tetrahydronaphthalene or decahydronaphthalene or a high molecular weight - 8 43671 liquid paraffin or mixture of paraffins which are liquid at the reaction temperature. The nature of the diluent is subject to considerable variation, although the diluent employed should be liquid under the conditions of polymerization and relatively inert.

The polymerization diluent employed in practicing this invention should be purified, for best results, from traces of moisture, oxygen, carbon dioxide and polar organic compounds prior to use in the polymerization reaction by contacting the diluent, for example, in a distillation procedure or otherwise, with e.g. an organoaluminum compound prior to or after percolating the solvent through silica gel or molecular sieves.

The polymerization time is not critical and will usually be of the order of thirty minutes to several hours in hatch processes. Contact times of from one to several hours are commonly employed in autoclave type reactions. When a 'continuous process is employed, the contact time in the polymerization zone can also he regulated as desired, and in some cases it is not necessary to employ reaction or contact times much beyond one-half to several hours since a cyclic system can be employed by removal of the polymer and return of the diluent, If used, and unreacted monomer to the charging zone where the 'catalyst can be replenished and additional monomer introduced.

The treated solid polymerization catalyst component of this invent! ls normally used with an additive to control molecular weight such as hydrogen. Solid polymers having molecular weights greater than 50,000 and less than 2,000,000 result thereby. The amount of hydrogen to be used depends upon the molecular weight distribution to be obtained and is well known to those skilled in the art.

The polyolefins prepared in accordance with this invention can be extruded, mechanically melted, cast or molded as desired. They can be used to form plates, sheets, films or a variety of molded objects. - 9 43 6 7 1 Preferably, the pressure range for the polymerization process using the treated catalyst component ia atmospheric to over 1000 p.s.i.g More preferably, the pressure range varies from 100 p.s.i.g. to 800 p.s.i.g. and, most preferably, the pressure range used in the instant process is 200 p.s.i.g. to about 700 p.s.i.g While the invention is described in connection with the specific Examples below, it is to be understood that these are for illustrative purposes only. Many alternatives, modifications and variations will be apparent to those skilled in the art in the light of the below Examples and such alternatives, modifications and variations fall within the scope and spirit of the appended claims.

GENERAL EXPERIMENTAL PROCEDURE The magnesium ethoxide used was a commercial product from Alfa Products. The aluminum'alkyl compounds were approximately 25 weight percent in heptane and were purchased from Texas Alkyls. The titanium tetrachloride was purchased from Matheson, Coleman and Bell-and is 99.5% by analysis, and the titanium tetrabutoxide was purchased from the Stauffer Chemical Company. Melt Indices were determined according to ASTM 1238. Particle size determinations were made by sieving which was done by placing ten grams of dried polymer product on a screen of the appropriate mesh size and gently shaking the screen for five minutes 3 6 71 EXAMPLE 1 A mixture of 13.9 grams of Mg(C^H,^ and 16.5 milliliters of Ti(0C^H9)^ was heated for 19 hours at 130-150°C. The mixture was cooled to 100°C and 35 milliliters of octane was added. The mixture was then allowed to cool to 35^0 and 385 milliliters of an ethylaluminum dichloride solution (25 weight percent in hexane) was added over a two hour period. The result was treated by passing 3,5 grams of hydrogen chloride gas through a stirred suspension of the catalyst at 21-29’C over a period of 110 minutes. Samples of the mixture were withdrawn several times and the final molar ratio, HC1/A1, of the slurry was 3.6.

A 0.67 milligram sample of the solid catalyst component was tested by activating it with 22 milligrams of triethylaluminum and placing the combination in a stirred autoclave reactor containing 225 milliliters of hexane and 22 milligrams of triethylaluminum at 180°C. The reactor contained a partial pressure of 80 p.s.i.g. of hydrogen and a total pressure of 300 p.s.i.g. which was maintained throughout the one hour reaction by addition of ethylene. A polymer yield of 53.5 grams was obtained which contained 52.5 percent fines (material passing through a 70-tnesh screen) compared to 75 percent fines for polyethylene made from a catalyst comprising triethyaluminum and untreated solid catalyst component. - 11 ι 436 71 EXAMPLE II Λ mixture of 114 grams of Mg(0C2H5)2, 136 grams of TiiOC^Hg),, and 100 milliliters of octane was heated at 129°C for 20 hours, after which one liter of hexane was slowly added and the mixture allowed to cool to room temperature. After the solid material was removed by filtration, 3.1 liters of Al(C2Hg)Cl2 solution (25 weight percent in hexane) uas added over a three-hour period and, after the mixture stood overnight, milliliters of a dilute triethylaluminum solution (24 weight percent in hexane) was added. An 80 milliliter portion of this mixture was diluted with 250 milliliters of hexane and hydrogen chloride was bubbled through It at a measured rate. The Table below indicates the amount of hydrogen chloride absorbed by the slurry at the time each of four 25 milliliter portions were removed for polymerization.

TABLE Solid Catalyst Temperature HCl Added Molar Ratio Component No. (°C.) (grams) HC1/A1(C,H5)C19 1 19 0 0 2 27.4 3.00 1.27 3 28.6 3.78 1.70 4 25.0 4.58 2.27 - EXAMPLE III Each of catalyst components from Example II numbers 1, 2, 3 and 4 and 22 milligrams of AlCCjH^lg, dissolved in 1-4 milliliters hexane, was used for the polymerization of ethylene employing a stirred autoclave reactor, 80 p.s.i.g. of hydrogen and a total pressure of 300 p.s.i.g. Polymerization time was one hour and polymerization temperatur 80 to 84°C in each run. The Table below sets out the polymerization results.

TABLE Solid Catalyst Component Polymer Weight Percent Amount Yield Through a 70 Mesh Number (milligrams) (grams) Screen (Percent 1 0.91 50.1 73.2 2 0.91 48.3 63.0 3 1.86 42.8 5.0 4 1.84 32.1 4.0 EXAMPLE XV 671 A mixture of 116.4 grams of magnesium ethoxide and 277 grams of tetrabutyltitanate was heated at 140°C until the solid had dissolved and then the flask was cooled to 110°C and one liter of hexane was added, cooling and diluting the solution to a final volume of 870 milliliters.

A 105 milliliter portion of the above mixture, 100 milliliters of hexane, 46.1 grams of zirconium tetrachloride and 360 milliliters of an ethylaluminum dichloride solution (50 weight percent in hexane) were heated at the reflux temperature of the solvent for one hour and 200 milliliters of hexane added when the mixture had cooled. A 200 milliliter sample of the resulting mixture was removed for testing and designated solid catalyst component 1.

A 505 milliliter portion of the supernatant liquid was removed from the remainder and replaced with an equal volume of hexane. Thereafter, the result was treated by passing 28.3 grams of gaseous hydrogen chloride through the slurry which retained 15.6 grams and thus was designated solid catalyst component 2. The HCl/ΑΙ ratio was 1.06.

Polymerization activity was tested by putting a mixture of the solid catalyst component and triisobutylaluminum in a stirred autoclave reactor containing 86 milligrams of triisobutylaluminum, 235 milliliters hexane, 200 p.s.i.g. hydrogen and enough ethylene, to maintain the total pressure at 300 p.s.i.g. After one hour at about 180°F the polymerization was terminated.

Weight Percent' Through a Solid Catalyst Component (i-Bu)3Al Promoter (milligrams) Polymer Yield (grams) M.I. (grams/ 10 min.) 70 Mesh Screen (percent) Number Amount (milligrams) 1 8.2 172 24.4 0.14 35 2 3.3 86 10.9 0.09 22 EXAMPLE V A mixture of 11.4 grams of magnesium ethoxide and 2.2 milliliters of titanium (IV) chloride in 100 milliliters of nonane was heated at 140°C for 45 minutes, cooled to ambient temperature, and 144 milliliters of ethylaluainum dichloride solution (50 weight percent in hexane) was slowly added to make solid catalyst component 1. After a sample of catalyst 1 was removed for testing, the supernatant liquid was decanted and replaced with hexane. Hydrogen chloride (4.04 grams) was passed through the stirred mixture which retained 2.37 grams to make solid catalyst component 2. The HC1/A1 molar ratio was about 1.45. The poly- merization runs were made in the same way as set out in Example V. Weight Percent iolid Catalyst Component Polymer M.I. Through a 70 Mesh Amount Yield (grams/ Screen Number (milligrams) (grams) 10 min.) (percent) 1 2.5 44.2 0.68 11 2 1.91 25.2 0.21 4 EXAMPLE VI A mixture of 11.4 grams of magnesium ethoxide, 2.7 milliliters of tetrabutyltitanate, 2.2 milliliters of titanium (IV) chloride, and 100 milliliters of nonane was heated at 140°C for one hour, cooled to ambient temperature, and 144 milliliters of ethylalumlnum dichloride solution (50 weight percent In hexane) added to make solid catalyst component 1. After a sample of solid catalyst composition 1 was removed for testing, the supernatant liquid was decanted and replaced with hexane. A 9.43 gram quantity of hydrogen chloride was passed with stirring through the - 14 4 3 6 71 remaining mixture which retained 5.85 grams Co make solid catalyst component 2. The HCl/Al molar ratio Is 1.44. The polymerization results using the procedure of Example I with the catalyst components/are shown below In the Table.

Claims (26)

1. WHAT WE CLAIM IS:

1. A process for treating a solid olefin-polymerization catalyst component containing from 0.1 to 15 wt./,, calculated as the metal, of a transition metal-containing material and formed, from: Cl) a magnesium compound; 2. (2) a transition metal-containing material which is a titanium (IV) alkoxide, alkoxycliloridc, or chloride; or a mixture thereof with a vanadium (V) alkoxide, alkoxychloride, or chloride; or with a zirconium (VI) alkoxide, alkxoychloride, or chloride v/herein each alkoxy group contains 1-6 'carhon atoms; and (3) an alkylaluminum compound to reduce the fines content of polymerized product formed by polymerizing one or more olefins in the presence of said soild catalyst component and added promoter, which process comprises contacting said catalyst component with at least one mol of hydrogen chloride per mol of alkylaluminum compound.

2. A process according to Claim 1 wherein the mol ratio of said alkylaluminum compound to the to Lal number of mols of said magnesium compound and transition-metal-containing material is between 0.2:1 and 10:1.

3. A process according to any preceding claim wherein the alkylaluminum compound is an alkylaluminum dichloride.

4. A process according to any preceding claim wherein the magnesium compound is a magnesium lower alkoxide.

5. A process according to Claim 1 and substantially as hereinbefore described.

6. A process for treating an olefin polymerization catalyst component which is substantially as described herein as a specific embodiment of the process defined in Claim 1,

7. A solid olefin polymerization catalyst component whenever treated by a process according to any preceding claim.

8. An olefin polymerization catalyst comprising (a) a catalyst component as defined in Claim 7 and (b) an effective amount of a promoter comprising a trialkyl aluminum, a dialkyl aluminum hydride or a dialkyl aluminum chloride.

9. An olefin polymerization catalyst component useful in the preparation of polyolefins containing reduced levels of fines comprising a solid prepared from: (a) the reaction product of (l) a magnesium compound; (2) a transition-metal-containing material which is a titanium (IV) alkoxide, alkoxychloride, or chloride; or a mixture thereof with a vanadium (V) alkoxide, alkoxyehloride, or chloride; or with a zirconium (IV) alkoxide, alkoxyehloride, or chloride; and (3) an alkylaluminum compound wherein each alkoxy or alkyl group contains 1-6 carbon atoms, using a mol ratio of said alkylaluminum compound to total mols of said magnesium compound and transition metal-containing material between 0.2:1 and 10:1; and (b) at least one mol of hydrogen chloride per mol of said alkylaluminum compound used, said solid containing from 0.1 to 15 wt.%, calculated as the metal, of said transition metal-containing material.

10. A catalyst component according to Claim 9 wherein said alkylaluminum compound is an alkylaluminum dichloride.

11. A catalyst component according to Claim 9 or Claim 10 wherein said magnesium compound is a magnesium di-lower alkoxide.

12. A catalyst component according tc any one of Claims 9 to 11 wherein said transition-metal-containing material comprises a titanium (IV) alkoxide. - 17 4 3 6 71

13. A catalyst component according to any one of Claims 9 to 12 promoted by a lower alkyl trialkyl-aluminum.

14. A catalyst component according to Claim 9 and substantially as hereinbefore described. 5

15. A catalyst component which is substantially as described herein as a specific embodiment of the catalyst component defined in Claim 9.

16. A catalyst for polymerizing ethylene or a mixture thereof with up to 20 mol % of a polymerizable Cj to Cg olefin to produce a 10 polymeric product containing reduced levels of fines comprising: (A) a solid component containing from 0.1 to 15 wt.%, calculated as the metal, of a transitional metalcontaining material and prepared from (1) the reaction product of (a) a magnesium 15 dialkoxide; (b) a transition metai-containing material which is a titanium (IV) alkoxide, alkoxychloride, or chloride; or a mixture thereof with a lower alkyl vanadium (V) alkoxide, alkoxychloride, or chloride; or with a zirconium (IV) alkoxide, alkoxychloride, or chloride; and (c) a alkylaluminum compound wherein each alkoxy or alkyl group contains '1-6 carhon atoms; and (2) at least one mol of hydrogen chloride per mol of alkylaluminum compound; and (B) a promoter which is a trialkylaluminum, a dialkylaluminum hydride, or a dialkylaluminum chloride.

17. A catalyst according to Claim 16 wherein (A) is prepared in the presence of an inert liquid diluent by reacting said magnesium 50 dialkoxide with said transition metal compound, reacting the product thereof with said alkylaluminum compound and thereafter treating with hydrogen chloride. 4 3 6 71

18. A catalyst according to Claim 16 wherein (A) is prepared in the presence of an inert liquid diluent by together reacting said magnesium dialkoxide, said transition metal compound, and said alkylaluminum compound and thereafter reacting with hydrogen 5 chloride.

19. A catalyst according to any one of Claims 16 to 18 wherein said promoter is a tri-lower alkylaluminum.

20. A catalyst according to any one of Claims 16 to 19 wherein said transitional metal compound comprises a titanium (IV) lower *|Q alkoxide.

21. A catalyst according to any one of Claims 16 to 20 wherein said magnesium dialkoxide is magnesium ethoxide.

22. A catalyst according to Claim 16 and substantially as hereinbefore described. ]5

23. A catalyst which is substantially as described herein as a specific embodiment of the catalyst component defined in Claim 16.

24. A process for polymerizing an olefin or mixture of olefins which comprises effecting said polymerization in the presence of a catalyst as claimed in any one of Claims 8 and 16 to 23. 20

25. A process for polymerizing an olefin according to Claim 24 and substantially as hereinbefore described.

26. Polyolefin whenever produced by a process according to Claim 24.