GB1595252A - Catalyst for olefinic polymerization - Google Patents

Description

(54) CATALYST FOR OLEFINIC POLYMERIZATION (71) We, EXXON RESEARCH AND ENGINEERING COMPANY, a Corporation duly organised and existing under the laws of the State of Delaware, United States of America, of Linden, New Jersey, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to unique and novel catalyst systems for the conventional alpha-olefin type polymerization at significantly improved polymerization activity, wherein the resultant polymers have a high degree of isotactic stereoregularity.

It is well known in the art to use an alkyl metal compound of Groups I--III in combination with a transition metal compound of Groups IVA--VIII as a catalyst system for olefinic polymerization. Although nearly all of the alkyl metal compounds are effective for the polymerization of ethylene, only a few are effective for the preparation of isotactic polymers of propylene and higher alpha olefins and only Et2AlCl and AlEt3 have any important commercial utility.

A major cost involved in the polymerization of the alpha olefins is the cost of the catalyst components. Therefore, the cost of the manufacture of the polymer can be effectively reduced by the use of catalyst systems having a higher polymerization activity. A further concern is the ability to produce polymers having a minimum amount of catalyst residues thereby eliminating a costly deashing operation. A still further concern is the ability to produce polymers having a high degree of isotactic stereoregularity thereby enabling the manufacturer to eliminate the costly operation involving the removal and separation of atactic polymer from the isotactic polymer. The improved catalyst system of the present invention provides a means for the manufacturer to obtain these desirable realizations.

The improved catalyst compositions of the present invention which may be employed in alpha-olefin polymerizations comprise a Group IVA-VIlI transition metal chloride or bromide or mixture thereof supported on a chloride lattice compound, an organo compound of Al, Ga, or In, and a mono-organo-magnesium compound. The Periodic Table which applies in this specification is that appearing in 'Notes on the use of the Classification, Key of Abridgments of Patent Specification'.

The transition metal catalyst compound is a Group IVA--VIII transition metal chloride or bromide and may be in the form of solid crystalline compounds, solid solutions or compositions with other metal salts. For highest stereospecificity it is desirable to have the transition metal chloride or bromide supported on a chloride layer lattice structure with very small crystallites, high surface area, or sufficient defects or foreign components to facilitate high dispersion during polymerization. By chloride layer lattice compounds we mean those compounds having layer structures in which the anion layers are predominantly chlorides. The transition metal chloride or bromide may also contain various additives such as Lewis bases, pi bases, polymers, or organic or inorganic modifiers. Vanadium and titanium halides such as VCl3,VBr3, TiC13, TiC14, TiBr3 or TiBr4 are preferred, most preferably TiC13 or TiCl4 and mixtures thereof. The most preferred TiCI3 compounds are those which contain TiCl4 edge sites on the layer lattice support such as alpha, delta, or gamma TiCl3 or various structures and modifications of TiCI3 or MgCl2. The most preferred TiC14 compounds are those supported on chloride layer lattice compounds such as MgCl2. Minor amounts of other anions may be also present instead of chlorine anions such as other halides, pseudohalides, alkoxides, hydroxides, oxides, or carboxylates. Mixed salts or double salts such as K2TiCI6 or MgTiCl6 can be employed alone or in combination with electron donor compounds. Other supports besides MgCI2 which are useful are hydroxychlorides. The most preferred crystal structure of TiCl3 is delta or pseudo delta, the latter being a mixture of alpha and gamma crystallites. The TiCl3-type catalysts may be prepared from TiCl4 by any one of the reduction and crystallization procedures known in the art (H2, metal, metal hydrides, metal alkyls, etc.). "Low aluminum" containing TiCI3 refers to TiCI3 catalysts which have low Al content because of the method of formation or because a major portion of the aluminum was removed in subsequent reactions.

The most preferred transition metal compound is TiCI4 supported on MgCI2 and optionally together with one or more Lewis bases.

The organo metal compound is R2WY, R3W or a mixture thereof, wherein W is Al, Ga or In, R is a primary alkyl (e.g. C, to C20 alkyl), secondary alkyl, tertiary alkyl, branched alkyl, cycloalkyl, naphthenic, aryl aralkyl or alkenyl (e.g. alkyl) groups which may also contain a Lewis base functionality, Y is Cl, Br, I, OR", SR" or OOCR", wherein R" is a primary alkyl (e.g. Cl to C20 alkyl), branched alkyl, cycloalkyl, aryl, naphthenic, aralkyl or alkenyl group, Y is preferably Cl, Br or I and more preferably Cl. Typical but non-limiting examples are diethyl aluminum chloride, aluminum triethyl, diethylaluminum bromide, diethylaluminum iodide, diethylaluminum benzoate, dioctylaluminum chloride, diethylgallium butoxide, diethylindium neodecanoate, triethylindium, dibenzylaluminum chloride, and mixtures thereof. Mixtures of organo metal compounds can be readily employed.

The C2-C4 alkyl aluminum compounds are preferred for high stereospecificity, and the dialkyl aluminum chlorides are most preferred.

The mono-organomagnesium compound has the general formula R'MgX wherein R' is a C, to C20 primary alkyl, C3 to C20 branched alkyl, C4 to C20 cycloalkyl, C2 to C20 alkenyl, C6 to C20 aryl, C, to C, aralkyl, or naphthenic group.

X is an anion which cannot initiate polymerization of olefins, such as Cl, Br, I, OR", SR" or OOCR", wherein R" is a primary alkyl, branched alkyl, cycloalkyl, alkenyl, aryl, aralkyl or naphthenic group. Typical examples are s-BuMgC1, t BuMgC1, s-BuMgOOCC6H, s-BuMgOC,5H31, EtMg neodecanoate, n BuMgOOCC6Hss, n-hexyl MgCI, n-hexyl MgOOCC9HI9, benzyl MgCI, crotyl MgOOCC6H,, and mixtures thereof. Mixtures of organomagnesium compounds can be readily employed. The most preferred X groups are OR" and OOCR" and the most preferred R' groups are secondary or tertiary alkyls.

Additionally, Lewis bases can be employed in the combination with the organo metal compound of Al, Ga and In, the organomagnesium compound and/or the Group IVA--VIII transition metal compound as long as they do not cause excessive cleavage of metal-carbon bonds, or loss of active sites. The Lewis base is defined as a tertiary amine, an ester, a phosphine, a phosphine oxide, a phosphate (alkyl, aryl), a phosphite, a hexa-alkyl phosphoric triamide, dimethyl sulfoxide, dimethyl formamide, a secondary amine, a dialkyl ether, an epoxide, a saturated or unsaturated heterocycle, a cyclic ether or a mixture thereof. Typical examples are diethyl ether or tetrahydrofuran.

Magnesium salts may also be employed with the catalysts of the invention if they are partially or wholly solubilized by reaction with the organo metal components. Examples include MgBr2, ClMgOR", R"OMgOOCR" and Mg(OR' '),.

The molar ratio of the organomagnesium compound to the organo metal compound (R2WY or R3W) is 10:1 to 1:10, preferably 2:1 to 1:2, more preferably 1:1. The number of moles of Lewis base can vary widely but is preferably equal to or less than the sum of the moles of the organo metal compound and the organomagnesium compound. The molar ratio of the organo metal compound or the organomagnesium compound to the transition metal compound is less than 20:1 and more preferably less than 10:1.

The catalyst system of the invention enables the process for making alpha olefin polymers having a high degree of isotactic stereoregularity to be carried out at a temperature of 250 to 1500C, preferably 40 to 800C, at pressures of 1 atm to 50 atm. The reaction time for polymerization is 0.1 to 10 hours, preferably 0.5 to 3 hours. Due to the high catalyst activity, shorter times and temperatures below 80"C can be readily employed.

The reaction solvent for the system can be any inert paraffinic, naphthenic or aromatic hydrocarbon such as benzene, toluene, xylene, propane, butane, pentane, hexane, heptane, cyclohexane or mixtures thereof. Preferably, excess liquid monomer is used as solvent. Gas phase polymerizations may also be carried out with or without minor amounts of solvent.

Typical examples of C2-C20 alpha-olefinic monomers employed in the present invention for the manufacture of homo-, co- and terpolymers are ethylene, propylene, butene- 1, pentene- 1, hexene- 1, octadecene- 1, 3-methylbutene- 1, styrene, vinylidene norbornene, 1,5-hexadiene and mixtures thereof. Isotactic polymerization of propylene and higher olefins is especially preferred.

The organo metal alkyl compound and organomagnesium compound can be added separately to the reactor containing the transition metal compound but are preferably premixed before addition to the reactor. Employing either the metal alkyl compound or the organomagnesium compound alone with the transition metal compound does not provide the improved catalyst efficiency and stereospecificity as envisioned in this application. In order to attain this, it is necessary to employ both the metal alkyl compound and organomagnesium compound in combination with the transition metal compound in the proportions previously defined. The concentration of the transition metal in the polymerization zone is 0.001 to 5 mM, preferably less than about 0.1 mM based on the amount of liquid monomer or liquid monomer plus diluent where a diluent is used, wherein mM represents millimolar, i.e. millimoles per litre of liquid monomer plus diluent if present.

EXAMPLE I Polymerizations were carried out in a 1 liter baffled resin flask fitted with a reflux condenser and stirrer. In a standard procedure for propylene polymerizations, 475 ml n-heptane ( < 1 ppm water) containing the alkyl metal co catalysts were charged to the reactor under N2, heated to reaction temperature (65"C) while saturating with propylene at 765 mm pressure. The powdered transition metal catalyst was charged to a catalyst tube such that it could be rinsed into the reactor with 25 ml n-heptane from a syringe. The propylene feed rate was adjusted to maintain an exit gas rate of 200500 cc/min. After one hour at temperature and pressure, the reactor slurry was poured into 1 liter isopropyl alcohol, stirred 2--4 hours, filtered, washed with alcohol and vacuum dried.

A titanium catalyst supported on MgC12 was prepared by combining 5 moles MgCl3, 1 mole TiCl4 and 1 mole ethylbenzoate, dry ball milling 4 days, heating a slurry of the solids in neat TiCI4 2 hours at 800 C, washing with n-heptane and vacuum drying. The catalyst contained 3.78% Ti. Portions of this catalyst preparation were used in the experiments shown in Table 1. Various control runs are shown for comparison with the cocatalysts of this invention (Runs A-F).

The sec-butyl magnesium was obtained from Orgmet and contained 72% non volatile material in excess of the s-Bu2Mg determined by titration, IR, NMR and GC analyses showed the presence of butoxide groups and 0.07 mole diethyl ether per s-Bu2Mg. The various s-BuMgX compounds were prepared directly by reacting an equimolar amount of ROH, RSH, RCOOH, etc. with the s-Bu2Mg.

TABLE 1 (0.2 g Catalyst, 500 ml n-C7, 65"C, 1 hr.) Mmoles Mmolks Mmoles Rate Run Al Cpd Mg Cpd Base g/g Cat/hr % HI Control I AlEt2Cl - - 47 67.1 Control I AlEt - 326 82.6 Control I AlEt2CI 0.83 (s-Bu)2Mg - 165 80.5 Control 1 AlEt3 0.83 (s-Bu)2Mg - 6 Control - 0.83 (s-Bu)3Mg O 0 Control - 0.83 s-BuMgC1 O G A 1 AlEt2Cl 1 s-Bu Mg OOCP 165 95.2 B 1 AlEt2Cl l-s-Bu MgOC,5H31 - 276 91.7 TABLE I (Continued) (0.2 g Catalyst, 500 n1l n-C7, 65 C, I hr.) Mmoles Mnioles Mmoles Rate un Al Cpd Mg Cpd Base g/g Cat/hr % HI 1 AlEt2CI I s-BuMgOC2H5 - 261 91.4 ) 1 AlEt2Cl 1 s-Bu MgSC12H25 - 310 93.2 1 AlEt2CI 0.83 s-Bu MgCI I Et3N 100 94.6 1 Et2AlOOC 1 s-BuMgCl - 351 90.5 + I Et (s-Bu)AlCl Compared to the control runs, which gave either low activity or low percent heptane insolubles (% HI), the new cocatalyst combinations gave high activity and stereospecificity ( > 90% HI).

EXAMPLE II A second catalyst preparation 2.68% Ti was made following the procedure of Example I except that a preformed 1:1 complex of TiCl4 . fCOOEt was used. In Runs G and H, the s-BuMgCl . Et2Owas obtained by vacuum stripping an ether solution of the Grignard reagent. In Run I, the n+s BuMgO()(S) was made by reacting pure (n+s Bu)2Mg with benzoic acid. Propylene polymerizations were carried out as in Example I (Table 2).

TABLE 2 Mmoles Mmoles Mmoles Rate Run Al Cpd Mg cpd Base g/g Cat/hr % HI G 1 AlEtCl2 1 s-BuMgCl 1 Et2O 0 H 1 AlEt2Cl 1 s-BuMgCl 1 Et3O 132 93.1 I AlEt3 I n+s-BuMgOOC - 123 89.7 Run G shows that monoalkyl aluminum compounds are not effective in combination with the mono-organomagnesium compounds in this invention. In contrast, our copending patent application 2353/78 (Serial No. 1,593,934) shows that such monoalkyl aluminum compounds are preferred when diorganomagnesium compounds are used.

Runs H and I show that dialkyl and trialkyl aluminum compounds are required for this invention.

EXAMPLE III The procedure of Example II was followed except that various magnesium compositions were used in combination with AlEt2CI and in some cases with Lewis base (Table 3). The Mg compounds were prepared as in Example I and II except for Run N in which pure s-Bu2Mg was reacted with s-butanol.

TABLE 3 Mmoles Mmols Run Mmoles Mg Cpd AlEt2CI Base Rate % HI J 1 n+s-BuMg neodecanoate 2 0 480 73.9 K Same as J 1 0 381 90.8 L I n-CI0H2,MgBr 1 1/3 Et2O 60 95.5 M 1 n-C6H,3MgOOCX 1 0 84 93.0 N 1 s-BuMgOs-Bu 1 1/3 Et2O 107 94.6 O 0.45 n+s-BuMgOOC# 1 0.6 Et2O IOI 95.9 0.55 n+s-BuMgOsBu 0.55 s-BuOMgOOC) Comparison of Runs J and K shows that decreasing the Al/Mg ratio from 2:1 to 1:1 gave a large increase in the percent heptane insolubles. Runs L-N show the results obtained with a variety of organic groups and anions on the magnesium component, as well as with added diethyl ether. Run 0 shows that excellent results were obtained with a mixture of the various components.

EXAMPLE IV Propylene was polymerized at 690 kPa pressure in a 1 liter stirred autoclave at 50"C: for 1 hour using the supported TiCI4 catalyst of Example Ill (table 4). lhe Mg compound was made as in Example I, Run A.

TABLE 4 g. Mmoles Run Cat Mmoles Mg Cpd AlEt2CI Solvent Rate % HI P 0.05 0.5 s-BuMgOOC) 0.5 n-C, 1292 89.9 Q 0.10 0.4 s-BuMgOOC) 0.4 n-C7 317 96.9 R 0.10 0.4 s-BuMgOOC) 0.4 Xylene 517 96.5 Comparison of Runs P and Q shows that the lower alkyl metaUcatalyst ratio in Q gave higher heptane insolubles. Run R in xylene diluent gave higher activity than Q in heptane.

WHAT WE CLAIM IS: 1. A catalyst composition suitable for use in an alpha-olefin polymerisation which comprises a mixture of: (a) a group IVA to VIII transition metal chloride, bromide or mixture thereof supported on a chloride layer lattice compound (as herein before defined); (b) an organo metal compound which is R2WY, R3W or a mixture thereof, wherein R is a primary alkyl, secondary alkyl, tertiary alkyl, branched alkyl, cycloalkyl, aryl, aralkyl or alkenyl group, W is Al, Ga or Ir and Y is Cl, Br, I, OR", SR" or OOCR", wherein R" is a primary alkyl, branched alkyl, cycloalkyl, aryl, naphthenic, aralkyl or alkenyl group; and (c) a mono-organomagnesium compound having the formula: R'MgX wherein R' is selected from a Cl to C20 primary alkyl, C3 to C20 branched alkyl, C4 to C20 cycloalkyl, C2 to C20 alkenyl, C6 to C aryl, C, to C20 aralkyl or naphthenic group and X is an anion which cannot itself initiate polymerisation of olefins wherein the molar ratio of the organomagnesium compound to the organo metal compound is from 10:1 to 1:10 and wherein the molar ratio of the organo metal compound or the organomagnesium compound to the transition metal compound is less than 20:1.

2. A composition according to Claim 1, wherein X is Cl, Br, I, OR", SR" or OOCR".

3. A composition according to either of Claims 1 and 2, wherein the metal of said transition metal chloride or bromide is trivalent titanium, trivalent vanadium or tetravalent titanium.

4. A composition according to Claim 3, wherein said transition metal chloride is TiCI3.

5. A composition according to any one of the preceding claims, wherein said support is MgCl2.

6. A composition according to Claim 3, wherein said transition metal chloride is TiCl4 on an MgCI2 support.

7. A composition according to any one of the preceding claims, wherein said organo metal compound is a dialkyl aluminium chloride.

8. A composition according to Claim 7, wherein said organo metal compound is Et2AICI.

9. A composition according to any one of the preceding claims, wherein said organomagnesium compound is s-BuMgOOCC6H5.

10. A composition according to any one of the preceding claims, which includes a Lewis base (as hereinbefore defined).

11. A process for the polymerisation of a C2 to C20 alpha olefinic monomer or a mixture thereof to a solid homo-, co-, or terpolymer which comprises contacting said monomer with a catalyst composition according to any one of the preceding claims at a temperature of 25"C to 1 500C, a pressure of 1 atm to 50 atm and for 0.1 to 10 hours, the concentration of the transition metal compound being 0.001 to 5 mM based on the amount of liquid monomer or liquid monomer plus diluent where a diluent is used.

12. A process according to Claim i 1, wherein the organo metal compound and the organomagnesium compound are premixed before addition to the reactor.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (14)

**WARNING** start of CLMS field may overlap end of DESC **. 50"C: for 1 hour using the supported TiCI4 catalyst of Example Ill (table 4). lhe Mg compound was made as in Example I, Run A. TABLE 4 g. Mmoles Run Cat Mmoles Mg Cpd AlEt2CI Solvent Rate % HI P 0.05 0.5 s-BuMgOOC) 0.5 n-C, 1292 89.9 Q 0.10 0.4 s-BuMgOOC) 0.4 n-C7 317 96.9 R 0.10 0.4 s-BuMgOOC) 0.4 Xylene 517 96.5 Comparison of Runs P and Q shows that the lower alkyl metaUcatalyst ratio in Q gave higher heptane insolubles. Run R in xylene diluent gave higher activity than Q in heptane. WHAT WE CLAIM IS:

1. A catalyst composition suitable for use in an alpha-olefin polymerisation which comprises a mixture of: (a) a group IVA to VIII transition metal chloride, bromide or mixture thereof supported on a chloride layer lattice compound (as herein before defined); (b) an organo metal compound which is R2WY, R3W or a mixture thereof, wherein R is a primary alkyl, secondary alkyl, tertiary alkyl, branched alkyl, cycloalkyl, aryl, aralkyl or alkenyl group, W is Al, Ga or Ir and Y is Cl, Br, I, OR", SR" or OOCR", wherein R" is a primary alkyl, branched alkyl, cycloalkyl, aryl, naphthenic, aralkyl or alkenyl group; and (c) a mono-organomagnesium compound having the formula: R'MgX wherein R' is selected from a Cl to C20 primary alkyl, C3 to C20 branched alkyl, C4 to C20 cycloalkyl, C2 to C20 alkenyl, C6 to C aryl, C, to C20 aralkyl or naphthenic group and X is an anion which cannot itself initiate polymerisation of olefins wherein the molar ratio of the organomagnesium compound to the organo metal compound is from 10:1 to 1:10 and wherein the molar ratio of the organo metal compound or the organomagnesium compound to the transition metal compound is less than 20:1.

2. A composition according to Claim 1, wherein X is Cl, Br, I, OR", SR" or OOCR".

3. A composition according to either of Claims 1 and 2, wherein the metal of said transition metal chloride or bromide is trivalent titanium, trivalent vanadium or tetravalent titanium.

4. A composition according to Claim 3, wherein said transition metal chloride is TiCI3.

5. A composition according to any one of the preceding claims, wherein said support is MgCl2.

6. A composition according to Claim 3, wherein said transition metal chloride is TiCl4 on an MgCI2 support.

7. A composition according to any one of the preceding claims, wherein said organo metal compound is a dialkyl aluminium chloride.

8. A composition according to Claim 7, wherein said organo metal compound is Et2AICI.

9. A composition according to any one of the preceding claims, wherein said organomagnesium compound is s-BuMgOOCC6H5.

10. A composition according to any one of the preceding claims, which includes a Lewis base (as hereinbefore defined).

11. A process for the polymerisation of a C2 to C20 alpha olefinic monomer or a mixture thereof to a solid homo-, co-, or terpolymer which comprises contacting said monomer with a catalyst composition according to any one of the preceding claims at a temperature of 25"C to 1 500C, a pressure of 1 atm to 50 atm and for 0.1 to 10 hours, the concentration of the transition metal compound being 0.001 to 5 mM based on the amount of liquid monomer or liquid monomer plus diluent where a diluent is used.

12. A process according to Claim i 1, wherein the organo metal compound and the organomagnesium compound are premixed before addition to the reactor.

13. A catalyst composition according to Claim 1 substantially as hereinbefore

described with reference to the Examples.

14. A process for the polymerisation of a C2 to C20 alpha olefinic monomer according to Claim 11 substantially as hereinbefore described with reference to the Examples.