ZIEGLER-TYPE CATALYST COMPOSITION

Abstract: A catalyst system for alpha-olefin type polymerizations, which includes at least one metal alkyl compound having the formula R n MR′ 3-n in combination with a Group IVA-VIII transi­ tion metal compound on a support and at least one Lewis base wherein R is C₃ to C₂₀ secondary or tertiary alkyl, cycloalkyl, alkenyl araralkyl groups; R′ is C₁ to C₂₀ primary alkyl, alkenyl or aralkyl groups, or hydrogen, M is aluminum, gallium, or indium; and n = 0-3. The improved catalyst system provides polymers having increased isotactic stereoregularity as well as lower catalyst residue.

Description: Title: TRIALKYL ALUMINIUM COCATALYST The present invention relates to catalyst systems for the conventional alpha olefin type polymerisation at significantly improved polymerization activity, wherein the resultant polymers have a high degrae of isotactic stereoregularity. An object of the present invention is to provide improved catalyst systems having a major increase in polymerization activity while being able to control over a wide range the polymer crystallinity, e.g., isotacticity, wherein the catalyst system includes a transition metal compound and a metal trialklyl compound of Al, Ga or In having at least one secondary or tertiary alkyl group. A further object of the present invention is to provide an improved process for alpha-olefin type polymerizations, wherein the polymerization activity is increased and the formed polymer has a high degree of isotactic stereoregularity and a minium amount of catalyst residues are formed. A still further object of the present invention is to use directly the new improved catalyst with various &num;types of supported transition metal compounds without substantial modification of the commercial catalyst preparation or the polymerizatiuon plant. A still, further object of the present invention i. to provide new improved catalyst composition wherein the isotacticity of the formed polymer is much less sensitive to a ratio of the cocatalyst (trialkyl metal compound) to the transition metal compound tn when the correspcnding primary alkyl compounds are used, thereby greatly facilitating process control to make higher quality polymers at more efficient production rates. Additionally, another object of the present invention is to provide a process and Compositions whereby R MR'2 or R2MR' are produced as cocatalysts in situ by the reactions: EMI3.1 It is well knows in the art to use an alkyl metal compound of Groups I-TII in combination with a transition metal compound of Groups IV4-VIII as a catalyst system for olefinic polymerization. While 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 rt2AlC1 AlEt3 and i-Bu2AlH have any important commercial utility. A major cost involved in the polymerization oX 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 pro- duce polymers having a thigh degree of isotactic stereoregularity thereby enabling the manufacturer- to eliminate or reduce 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 to the manufacturer of obtaining these desirable realizations. The improved catalyst systems of the present invention which are employed in alpha olefin polymerizations include a Group IVA-VIlI transition metal compound, one or more Lewis bases, and at least one metal alkyl compound at least one of which is a metal trialkyl compound of Al, Ga or In, wherein at least one of the alkyl groups is. selected from the group consisting of C3 to C20 secondary or tertiary alkyl, cycloalkyl, alkenyl or aralkyl groups. The transition metal catalyst compound is a Group UA -VIII transition metal halide, wherein the halide group is chloride or bromide and the transition metal halide is in the form of solid crystalline compounds, solid solutions or compositions with other metal salts or supported on the surface of a wide range of solid supports. For highest stereospecificity it is desirable to have the transition metal halide, or its support composition, in the layer lattice structure with very small crystallites, high surface area, or sufficient defects or foreign components to facilitate high dispersion during polymerization. The transition metal halide may also contain various additives such as Lewis bases, pi bases, polymers or organic cr inorganic modifiers. Vanadium and titanium halides such as VC13, VBr3, TiC13, TiCl47 TiBr3 or TiBr are treferred, most preferably TiC13 or TiC14 and mixtures thereof. The most preferred TiC13 compounds are those which contain TiC14 edge sites on G layer lattice support such as alpha, delta, or gamma TiC13 or various structures and modifications of TiC13 MgCl2 or other inorganic compounds having similar layer lattice structures. The most preferred TiC14 compounds are those supported on chloride layer lattice compounds such as MgC12. Other anions may be also present, such as other halides, pseudo-halides, alkoxldes, hydroxides, oxides orcarboxylates, etc., providing that sufficient chloride is available for isospecific site formation. Mixed salts or double salts such as K2TiCl6 or MgTiCl6 can be employed alor or in combination with electron donor compounds. Other supports besides MgCl2 which are useful are Hydroxychlorides, oxides or other inorganic or organic supports. The most preferred transition metal compound is TiC14 containing MgCl2 especially in the presence of Lewis bases (electron donor compounds). The Lewis bases can be employed in combination with the trialkyl metal compound or with the Group IVA -VIII transition metal compound or with both components as long as they do no cause excessive cleavage o metal-carbon bonds cr loss of active sites. A wide variety of Lewis bases may be used including sucn types as tertiary amines, esters, phosphines, phosphine oxides, phosphates (alkyl, aryl), phosphites, hexaalkyl phosphoric triamides, dimethyl suloxide, dimethyl formamide, secondary amines, ethers, epoxies, ketones, saturated and unsaturated heteroxycles, or cyclic ethers and mixtures thereof. Typical but nonlimiting examples are diethyl ether, dibutyl ether, tetrahydrofuran, ethyl acetate, methyl p-tcluate, ethyl p-anisate, ethyl benxoate, phenyl acetate, amyl acetate, methyl octanoate, acetophenone, benzophenone, triethyl amine, tributylamine, dimethyl decylamine, pyridine, N-methylpiperidine, 2,2,6,6-tetramethylpiperidine and the like. Especially useful in combination with the trialkyl metal cocatalyst are Lewis bases whose complexing ability toward the cocatalyst is hindered sufficiently by steric and/or electronic effects to cause appreciable dissociation of the trialkyl metal Lewis base complex under polymerization conditions. A1- though a wide range of mole ratios may be used, dissociation measured on a 1:1 complex is normally in the range of 5-95, preferably greater than iO and less than 90%. Steric hinderance is achieved by bulky substituents around the heteroatom which reduces the accessibility of the base functionality to the Lewis acid, that is, the trialkyl metal compound. Electronic hindering is obtained by placing electron withdrawing substituents on the heteroatom to reduce the electron density on the basic heteroatom. Aromatic substituents are especially useful because they are relatively unreactive toward other catalyst Components. Hindered Lewis bases derived from siperldines, pyrrolidines, ketones, tetrahydrofurans, secondary and tertiary aromatic amines and tertiary aliphatic amines are preferred, with the hindered nitrogen bases being most referred. Non-limiting examples of sterically hindered bases include 2,2,6,6tetramethylpiperidine, 2,2,5,5-tetramethylpyrrolidine, 2,2, 5,5,-tetramethyltetrahydrofuran, di-tert-butylketone, 2,6di-isopropyl-piperidine, ostho-tolyl t-butylketone, methyl 2,6-di-tert-butylphenylketone, diisopropylethylamine, t-butyldimethylamine, 6-methyl-2-isopropyl pyridine, and the like. Electronically hindered Lewis bases include diphenylamine, di-ortho-tolylamine, N,N-diethylaniline, di-orthotolylketone, and the like. Since aromatic substituents are also bulky, some of the electronically hindered bases also have a steric contribution to the hinderance. Especially preferred hindered amines are 2,2,6,6-tetramethyl-piperidine, 2,2,5,5-tetramethylpyrrolidine and the diarylamines. Com- pletely hindered bases, such as 2,6-di-tertiary-butylpyridine and the like, which complex the alkyl metal cocatalyst too weakly, are ineffective for improving stereospecificity and are excluded iron this invention. Salts of Group IA-IITB metals may also be employed with the present catalysts if they are partially or wholly solubilized by reaction with the alkyl metal components. Particularly useful are the carboxylates, alkoxides and aryloxides of magnesium and aluminum. Non-limiting examples include Mg(OOCR")2, R"MgOOCR", ClMgOR", Mg(OR")2, R"2AlOOCC6H5, R"Al(OOCR")2, R"2AlOR", and the like, where R" is a hydrocarbyl group. Most preferred are the alkoxide and carboxylate salts of magnesium and aluminum prepared in situ by reacting the crganometal compounds with R"OH or carboxylic acids in hydrocarbon solvents, Sterically hindered alkoxides and aryloxides are especially preferred, where R" = t-butyl, t-amyl, 1,1-diethylpropyl,1,1-diethyl benzyl, 2,6-di-tert-butylphenyl, 1,1-diphenylpropyl, triphenylmethyl, and the like. These salts of Group IA-IIIB are preferably used with the trialkyl metal compounds having the formula R"'3M wherein 1M = Al, Ga or In, and R"' is selected from the group consisting of a C1-C20 primary, secondary or tertiary alkyl branched primary alkyl, cycloalkl, alkenyl cr aralkyl group and mixtures thereof, more pre ferably at least one alkyl group having at least two carbon atoms, and most preferably having 2 to 4 carbon atoms, , The salt of the Group IA-IIIB metal is used at a molar ratio of 1 to 50 to 50 to 1 moles of the salt of Group IA-II metal per mole of the trialkyaluminium compound R"3Al, preferably 1 to 10 to 10 to 1 moles when the oxygen-contain- ing group is alkoxide or aryloxide. When the group is carboxylate, the ratio is 0.1 to 1, preferably 0.1 to 0.5 carboxylate groups per mole of the trialklyl metal compound. The use of these Group IA-IIIB metal salts is preferably with the supported titanium catalyst systems as embodied in the present invention. The improved cocatalyst of the present invention have the general formula RnMR'3-n wherein M = Al, Ga, or In, R is selected from the group consisting of a C3-C20 secondary or tertiary alkyl cycloalkyl, alkenyl or aralkyl group, R' is selected from the group consisting of C1-C20 primary alkyl, alkenyl or aralkyl or hydride; and n = 0-3, preferably 1-2, and most preferably n = 2. Preferably, R' is C2-C10 primary alkyl or aralkyl, or hydride; most preferably R' is C2-C4 primary alkyl or hydride with the restriction that not more than one hydride group may be present. The group is preferably about a C4-C16 secondary or tertiary alkyl group cr cycloalkyl group and is most preferably one which is not readily susceptible to elimination or displacement by monomer during polymerization. In addition to the simple secondary alkyl groups, other groups are also effect- ive in which the aluminium is attached to a secondary or tertiary carbon atoms, i.e., cxclohexyl, cyclooctyl, tert butyl, tert-amyl, s-norbornyl, and the like. The most preferred compositions have the formula RnAlR'3-n in which the secondary and tertiary alkyl groups contain 4-10 carbons and n = 2. Mixtures of the cocatalysts cf this invention with conventional alkyl metal cocatalysts also yields improved results. Suitable non-limiting examples include i-Pr2AlEt, s-BuAlEt2, s-Bu2AlEt, t-BuAlEt2, t-Bu2AlEt, s-Bu3Al, 1,1dimethylheptyl AlEt2, s-Bu2Aln-C16H33, t-Bu2AlCH2C6H5, s-Bu(t-Bu)Aln-Bu, cyclohexyl2AlEt, s-pentyl Ali-Bu2, t-Bu2AlMe, t-Bu2Aln-C8H17 (2-ethylcyclopentyl)2AlEt, 2 (3-ethylnorbornyl)AlEt2, 2-norbornyl Ali-Bu2, (2-norbornyl)2 All-Eu, acenaphthyl Ali-Bu2, cyclooctyl (i-Bu) A1E, 3-ethyl5-ethylidinenorbornyl AlEt2, 9-i-bu-9-alumino-3,3,1-bicyclononane, s-Bu2AlH, t-Bu2AlH, t-Bu2InEt, s-Bu2GaEt, neopentyl AlEt2, neopentyl2 AlEt and the like. Preferred compounds include those in the above list which have the formula R1-2AlR'2-1, The most preferred compounds in the above list have the formula R2A1R'. One method of preparing these secondary alkyl aluminum compounds is to react internal olefins with AliBu3 or i-Bu2AlH to add Al-H across the double bcnd to form alkyl aluminum compounds. ?7hen the double bond is in a strained ring compound, AlR3 may be used to add- Al-R across the double bond and obtain preferred compound which are very resistant to displacement or elimination. Strainea ring olefins include cyclopentene, norbornene, norbornadiene, ethylidine norbornene, dicyclopentadiene, and the like. This method is preferred because of raw material availability and simplicity of reaction, although this invention is not limited by the method of synthesis Other methods include the direct synthesis from the reactive metals and the secondary or tertiary halides, the various organometallic svntheses involving liana eschange between Al, Ga or in compounds and secondary cr tertiary alkyl metal compounds of cre electropositive metal@ @@@ @@@@@@@@@@@@ @@@@@@@@@@ reaction of the metal@@ @@@@@@@@@@@ @@@@@@@@@@@ @ends. Particularly useful is the general @erm@@ of secondary or tertiary alkyl lithium compounds with R'HX2 or R2 MX because it takes place readily in dilute hydrocarbon solutions. Through di-secondary alkyl aluminum compounds are preferred of mono-secondary alkyl compounds, the monoalkyl types become more effective the greater the steric bulk of are group among as it does not interfere with active salt formation or lead to decomposition under reaction conditions. For one alkyl metal @@catalysts of this invention, the most prferred transition metal compounds contain TiCl4 supported on MgCl2 and one or more Lewis bases. The concentration of the transition metal in the polymerization zone is 0.001 to 5 ml, preferably less than 0.1 mM. The molar ratio of the trialkyl metal compound to the transition metal compound is 0.5:1 to 200:1 or higher, more preferably 5:1 to 100:1. The molar ratio of Lewis base to organometal compound can vary widely but is preferably 0.1:1 to 1:1. However, the hindered Lewis bases may be added in gerater than equimolar amounts, from 0.1 to 1 to 10 to 1 moles per mole of organometal compound to obtain higher stereospecificity without a major loss of activity which would occur with unhindered bases. Surprisingly, it has been found that the Group IA-IIIB salts may be limitted when a hindered Lewis base is used together with th trialkyl metal cocatalyst. Both high activity and high stereospecificity are obtained when the Lewis base is sufficiently hindered to prevent poisoning the spereospecific catalyst sites. In such cases, an excess of the hindered base over the alkyl metal cocatalyst still produces high activity, thereas an excess of the less hindered metal complating@, kills the catalyst. The desired steric @@@@@@@@@@@ @@@@@@@@ @@ and name as defined above for dissociation @@@@ and @@@@ling bound compound in this system, the less hindered trialkyl metal compounds are preferred (MR The catalyst system o- tne invention enables the process or making alpha olefin polymers having a high degree of isotactic stereoregularity to be carried out at a temperature of about 250 to about 150 C., more preferably about 400 to about 30 C., at pressures of about 1 atm. to about 50-atm. The reaction time for polymerization is about 0.1 to about 10 hours, more preferably about 0.5 to about 3 hours. Due to the high catalyst activity, shorter times and temperatures below SOOC. can be readily employed. The reaction solvent for the system can be any inert paraffinic, naphtenic or aromatic hydrocarbon such as benzene, toluene, xylene, propane, butane, pentane, hexane, heptane, cyclohexane, and mixtures thereof. Preferably, excess liquid monomer is used as solvent. Gas phase polymerizations may also be carried out with or with- out minor amounts of solvent. Typical, but non limiting examples of C2-C20 alpha olefinic monomers employed in the present invention for the manufacture of homo-, co- and terpolymers are ethylene, propylene, butene-l, pertene-l, hexene-l, octadecene-l, 3methylbutene-1, styrene, ethylidene norborene, 1,5-hexadiene and the like any mixtures thereof. Isotactic polymerization of propylene and higher olefins is especially preferred, including block copolymerizations with ethylene. The trialkyl metal compound and the supported transition metal compound can be added separately to the reactor or premixed before addition to the reactor, but are preferably added separately. Replacing the secondary or tertiary alkyl groups by bulky or hindered alkoxy, phenoxy cr dialkylamide groups does not provide the improved catalyst activity achieved by the cocatalyst in this -invention. An alternative embodiment of the present invention with respect to the cocatalysts (RnMR'3-n) is to use directly the reaction product ci EMI10.1 exemplified in French Specification 2360303; or RMgX' + R2'MX RMR'2 + MgXX' as exemplified in French Specification 238030 wherein the present application is related to both or these French Specifications. 2380303 and 2380304 In the case of the rormation of R2MR', the metal di- or trihalide compounds which are used are selected from the group consisting essentially of a metal halide compound selected from the group consisting of R'MX2, MX3 and mixtures thereof, wherein M is selected from the group consisting of Al, Ga, and In, R' is selected from the go consisting of C1 to C20 primary alkyl, alkenyl or aralkyl groups or hydride; ; X is selected from the group consisting of chloride, bromine or a mcnovalent anion which cannot initiate polymer ratio of olefinic monomers, wherein the anion is selected from the group consisting of alkoxide, phenoxide, thioalkoxide, carboxylate, etc. and mixtures thereof. Typical but non limiting examples are ethyl aluminum dichloride, aluminum trichloridem ethyl aluminum dibromide, ethyl chloroaluminum bromide, octyl aluminum dichloride, ethyl indium dichloride, butyl aluminum dichloride, benzyl aluminum dichlorice, ethyl chloroaluminum butoxide, and mixtures thereof. fixtures or metal halide compounds can be readily employed. The C2-C4 all aluminum dihalides are most preerred for high stereospecificitv and the monoalkylaluminum dichlorides are most preferred. The diorganomagnesium compound has the general formula R2Mg wherein R can be the same of different and is selected from the group consisting of C3 to C20, secondary or tertiary alkyl, cycloalkyl, aralkyl or alkenyl groups. Typical, but non limiting examples are (s-Bu)2Mg, (t-Bu)2Mg or (iPr)2Mg. Mixtures of diorganomagnesium compounds can be readily employed providing at least one secondary or tertiary group is resent. The most trererred organic groups are secondary ann tertiary alkyl groups, e.g. t-Bu s-Bu. The molar ratio of the alkyl metal halide compound (R'MX2) to the diorganomagnesium compound is 0,5:1 to 2:1, more preferably 0.7:1, and most preferably 1:1. or the MX3 compound the ratio is 1:1 1 to 1:3, most preferably 2:3. The nmhber of moles of Lewis base can vary widely but is preferably equal to or less than the sum of the moles of the metal halide compound and the diorganomagnesium compound. The molar ratio cf the metal halide compound or the diorganomagnesium compound to the transition metal compound is less than 200:1 or higher and more preferably less than 100:1. The metal halide compound and diorganomagnesium compound can be added separately t the reactor containing the transition metal compound but are preferably premixed before addition to the reactor. Employing either the metal halide compound or the diorganomagnesium compound alone with the transition metal compound does not provide the impoved catalyst efficiency and stereospecificity as envisioned in this application. In order to attain this, it is necessary to employ both the metal halide compound and diorganomag- nesium compound in combination with te transition metal compound in the critical proportions as previously defined. The concentration of the transition metal in the polymerization zone is 0.001 to 5mM, preferably less than 0.1 mM. In the case of the formation of RMR2', the metal alkyl compounds which are used are selected from the group consisting essentially of a metal alkyl compound selected from the group consisting of R2'MX or R'3M and mixtures thereof, wherein M is selected from the group consisting of Al, Ga and In, R is selected from the group consisting of C1 to C20 primary alkyl, alkenyl, aralkyl or hyride groups; X is selected from the group consisting of monovalent anion which cannot initiate polymerization of olefins, such as F, Cl, Sr, O", SR" and COCR", wherein " is selected from the group consisting of Cl to C20 alkyl, branched alkyl, cycloalkyl, aryl, naphthenic, aralkyl and alkenyl groups, X is more preferably Ci or Er and most preferably Cl. Typical but non limiting examples are diethyl aluminum chloride, aluminum triethyl, diethylaluminum bromide, diethylaluminum iodide, diethylaluminum benzoate, diisobutylaluminum hydride, dioctylalumimum chloride, diethylgallium butoxide, diethylindium neodecanoate, triethylindium, dibenzylaluminum chloride and mixtures thereof. Mixtures of metal alkyl compounds can be readily employed. The C2-C4 alkyl aluminum compounds are preferred for high stereo- specificity, and the dialkyl aluminum chlorides are most pre-errec:. The mono-organomagneslum compound has the general formula RigX wherein R is selected from the group consisting of C3 to C20 secondary or tertiary alkyl, cycloalkyl, aralkyl or alkenyl groups. X is selected from the group consisting of an anion which cannot initiate polymerization of olefins, such as C1, Br, OR", SR", and OOCR", wherein R" is selected from the group consisting of C1 to C20 alkyl, branched alkyl, cycloalkyl naphthenic, acryl, aralkyl, allyl and alkenyl groups. Typical, but non limiting examples are s-BuMgCl, t-BuMgCl, s-BuMgOOCC6H5, or s-BuMgOC15H31, and mixtures thereof. Mixtures of organomagnesium compounds can be readily employed. The most preferred X groups are OR" and COCR" and the most preferred R groups are secondary or tertiary alkyl. The molar ratio of the organomagnesiun RMgX compound to the metal alkyl compound (R'2MX or R'3M) is 2:1 to 1:2, most preferably 1:1. The number of mcles of Lewis base can vary widely but is preferably equal to or less than the sum of the moles of the metal alkyl compound and the organomagnesium compound. The molar ratio of the metal alkyl compound or the organomagnesium compound to the transition metal compound is less than 200:1 or higher and more preferably less than 100:1. The metal alkyl compound (R'2MX or R'3M) and organomagnesium compound RMgX can be added separately to e reactor containing tre 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 desirable to employ both the metal alkyl compound and organomagnesium compound in combination with t transition metal compound in the proportions previously defined. he concentratIon of the transition metal in the polymerization zone is 0.001 to about 5mM, preferably less than 0.1 mM. The advantages of the catalyst system and the process for the alpha olefin polymerizations of the present invention can be more readily appreciated by reverence to the following Examples and tables. EXAMPLE 1 An aluminum alkyl compound containing both secbutyl and ethyl groups was prepared by mixing equimolar amounts of (sec-butyl)2Mg'0.16 EtO and ethyl aluminum dichloride in heptane, heating to 65 C, 15 min., separating the magnesium chloride solids and vacuum stripping the clear solution. N:R analysis indicated the composition sBu2AlEt 0.45Et2O. Petals analysis showed that only 0.50% Mg was present in this faction. The above liquid alkyl aluminum compound (0.2g) was used as cocatalyst with 0.2 g catalyst prepared by reacting anhydrous MgCl2 (5 moles) with TiCl4#C6H5COOEt (1 mole) in a ball mill 4 days, followed by a neat TiC14 treat at SOOC, 2 hours, washed with heptane and vacuum dried. The catalyst contained 2.68% Ti. Propylene was polymerized in 500 ml n-heptane at 65 C., 1 hour at 765770mm. Polymerization rate was 130 g/g catalyst/hour and the polymer insoluble in boiling heptane = 97.6%. EXAMPLE 2 Three alkyl aluminum compounds containing sec-butvl groups were prepared by reacting the proper stoichiometric amounts of sec-butyl lithium in heptane with either ethyl aluminum dichloride or diethylaluminum chloride, heating to boiling, filtering the insoluble LiCl, and vacuum stripping the clear solutions. Nearly theoretical yields were obtained of s-BuETAlCl (A), s-Bu2EtAl (B) and s-BuEt2Al (C). Compositions were established by ÚH and 13C NMR and by G.C. analysis of the alkyl fragments. Polymerizations were carried out as in Example 1 using 1 mmole aluminum alkyl compound and 0.2 a of the supported TiCl4 catalyst. The results summarized in Table I are compared to those obtained using the control ethyl aluminum compounds. In all tree runs with sec-butyl alkyls, both activity and stereospecificity (heptane insoiubles) were higher than those obtained with the conventional ethyl aluminum compounas. The trialkyls were far superior to the dialkyl aluminum chlorides and the di-sec-butyl aluminum ethyl was clearly superior to the mono-sec-butyl aluminium diethyl compound. TABLE I Rate Run Al Alkyl 2 Cat/hour 7. HI A vt2AlC1 control 4809 68.0 B s-Bu1.07EtAlCl0.93 64.6 79.1 C Et3Al control 344 83.1 D s-BuEt2Al 380 90.3 E s-Bu2EtAl 357 93.0 EXAMPLE 3 Sec-pentyl aluminium diisobutyl wasprepared by reacting 19.57 g i-Bu2AlH with 75 ml pentene-2 in a glass lined 300 cc bomb at 135-140 C. for 15 hours, then 150 C. for 7 hours. The solution was vacuum stripped at 250C., yielding 28.1 g of the neat sec-pentyl aluminum compounds. Propylene was polymerized as in Example 2 using 0.212 g (1 mole) sec-pentyl aluminium diisobutyl as cocatalyst. Polymerization rate was 383 g/g Cat/hr and %HI = 92.7. Comparison with AlEt3 control (Ex. 2, Run C) shows that the sec-pentyl aluminum compound gave substantial improvement, particularly in stereospecificity. EXAMPLE 4 The alkyl metal cocatalysts of the Invention are particularly advantageous in having a much smaller effect of concentration (or alkyl metal/Ti) on stereospecificity, thereby simplifying plant operation and permitting better control of product quality. The results are summarized in Table II for ni-sec-butyl aluminium ethyl in contrast to AlEt3 using the propylene polymerization procedure of Example 2. TABLE II Run Al Alkyl Conc. mM Rate % HI F s-Bu2AlEt 2 357 93.0 G s-Bu2AlEt 4 484 83.4 H AlEt3 Control 2 344 83.1 I AlEt3 Control 4 290 64.9 The above examples illustrate that trialkyl aluminum compounds containing at least one secondary alkyl group are superior cocatalysts in Ziegler type polymerizations of alpha olefins and that di-secondary alkyl aluminum compounds are preferred. EXAMPLE 5 Various secondary norbornyl aluminum n-alkyl compounds were prepared by reacting the stoichlometric proportions of a norbornene compound with either i-Bu2AlH or AlEt3 at elevated temperatures and removing unreacted materials by vacuum stripping. Structures were shown by 1H and 13C NMR to be the expected addition products of Al-H or Al-Et across the norbornene double bond. These mono and di-secondary alkyl aluminum compounds were used in propylene polymerization following the procedure of Example 2. TABLE III Run Al Alkyl Rate % HI J 2-Norbornyl AliBu2* 344 90.2 K (2-Norbornyl)2AliBu* 247 91.8 L 3-Ethyl-2-norbornyl AlEt2* 322 92.5 M 3-Ethyl-5-ethylidene-2- 247 93.7 * Other isomers may also be present. Comparison with the AlEt3 control (Run C, Example 2) shows that all of the secondary norbotnyl aluminum alkyls gave markedly higher heptane insolubles while retaining high activity. EXAMPLE 6 Sec-alkyl aluminum hydrides also give improved results compared to the closely related primary alkyl aluminium halide (i-Bu2AlH), following the procedure of Example 2. TABLE IV Run Al Alkyl Rate % HI N i-Bu2AlH control 456 83.1 O s-Bu2.6AlH0.4 462 85.8 Alet3 control 241 82.3 Q* iBu3Al control 264 89.3 R* s-Bu2.6AlH0.4 284 90.7 S* s-Bu2.3AlH0.7 223 90.1 * Another catalyst preparation was used. It was made by ball milling 5 moles MgCl2 with 1 mole ethylbenzoate for one day, adding 1 mole TiC14 and milling 3 days, then treating with neat TiCl4 at 800C., for 2 hours, washing with heptane and vacuum dried. The catalyst contained 3.44% Ti. Run 0 using sec-butyl groups gave higher activity and stereospecificity than Run N using the closely related, but primary, isobutyl groups. Improved results are also seen versus the AlEt3 control using the same supported titanium catalyst (Example 2, Run C). Runs R and S show substantially higher heptane insolubles using two different sec-butyl aluminum hydrides compared to control Runs P and Q using AlEt3 and iBu3Al with the same catalyst. EXAMPLE 7 The procedure to Example 2 was followed except that various Lewis bases were mixed with the aluminum alkyl solution before charging to the reactor. TAB Run Al Alkyl mmoles Base Rate % HI T AlEt3 control 0.16 Et23O 358 84.7 U s-3u2AiEt 0.16 Et2O 289 94.4 V t-Bu2AlEt 0.1 Me p-toluate 327 94.0 W t-Bu2AlEt 0.3 Et p-anisate 79 97.3 x t-Bu2AlEt 0.9 .Et20 56 98.0 Y t-BuAlEt2 0.9 Et2O 101 97.1 z* t-BuilEt 0.2 acetophenone 196 94.2 AA* t-Bu2AlEt 0.2 ethylacetate 74 97.6 *Used catalyst preparation described in Example 6, Runs P-S. The improved stereospecificities obtained with the cocatalysts of this invention are further increased by the addition of Lewis bases (Runs U-AA versus control Runs T and Example 2, Run C). At the higher amounts of base, 97-98% HI was obtained, which is sufficiently high to eliminate the need for rejection of atactic polymer and greatly simplify the process. Activity is decreased somewhat, but it is still 3-5 times that the the Et2AlCl/TiCl30.33AlCl3 commercial catalyst (rate = 20, HI = 93). At somewhat lower base concentrations, activity is 10-20 times higher than the commercial catalyst while still achieving 1-2% higher heptane insolubles. XAMPLE 8 Following the procedures of Example 2 and Example 7, improved stereospecificity is also obtained using t-Bu2InEt cocatalyst. EXAMPLE 9 The procedure of Example 6, Runs P-S was followed except that 9-i-Bu-9-alumino-3,3,1-bicyclononane was used as cocatalyst. Polymerization rate = 97.5 g/g catalyst/hour; =85.1%. Example 10 The procedure of Example 9 was ollowed except that t-Bu2Al (n-octyl) was used as cocatalyst. The rate was 212 g/g catalyst/hour; HI = 93.0%. EXAMPLE 11 Polymerizations were carried out in a 1 liter baffled resin flask fitted with an efficient reflux con dense and a high speed stirrer. In a standard procedure for propylene polymerizations, 475 ml h-heptane (1 ppm water) containing 10 mmole EtnAlCl (1.20 g), or the mixture of cocatalysts, was charged to the reactor under dry N2, heated to reaction temperature (65 C.) and saturated with pure propylene at 765 mm pressure. The TiC13 (1.00 g) (6.5 mmole) was charged to a catalyst tube containing a stopcock and a rubber septum cap. Polymerization started when the TiC13 was rinsea into the reactor with 25 ml n-heptane from a syringe. Propylene feed rate was adjusted to maintain an exit gas rate of 200-500 cc/min at a pressure of 765 mm. after one hour at temperature and pressure, the reactor slur was poured into one liter isopropyl alcohol, stirred 2-4 hours, filtered, washed with alcohol and vacuum dried. The TiC13 was prepared by reduction of TiC14 with Et2AlCl followed by treatment with diisopentyl ether and TiCl4 under controlled conditions, yielding a high surface area delta TiC13 under controlled conditions, yielding a high surface area delta TiCl3 having low aluminum content. The sec-butyl magnesium in Runs B. D. and E 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 dimethyl ether per s-Bu2Mg. A second sample of (s-Bu)2Mg was used in Runs G and I. It was substantially pure s-Bu2Mg but contained 0.33 mole diethyl ether per s-Bu2Mg (Table VI). TABLE VI Mmoles Rate Run TiCl3 EtAlCl2 (s-Bu)2Mg Et2AlCl g/g/hr % H1 A(Control) 1(a) 0 0 10 33 95.2 B 1(a) 5 5 0 152 52.6 C(Control) 1(b) 0 0 10 85 96.3 D 0.2(b) 0.4 0.2 1.6 123 88.0 E 0.2(b) 2 2 0 210 49.2 F(Control) 1(c) 0 0 5 8 79.5 G 1(c) 2.5 2.5 0 36 57.6 H(Control) 1(d) 0 0 10 20 91.7 I 0.2(d) 1 1 0 200 57.4 (a) and (b) were different preparation sof low aluminium TiCl3 catalyst. (c) Stauffer HA grade TiCl3 (hydrogen-reduced, dry ball milled). (d) Stauffer AA grade TiCl3#0.33 AlCl3 (aluminium-reduced, dry ball milled). Comparison of Runs B,D,E,G and I with their respectiv control runs A,C,F and H shows that each type cf TiCl3 catalyst the nove cocatalyst combination gave 2-10 times higher activity than the customary Et2AlCl cocatalyst. The percent heptane insoluble (%HI) decreased substantially using the new cocatalysts. Thus, these high activity catalysts are attractive for making low crystallinity homopolymers or propylene and higher alpha olefins. They are particularly attractive for making thermoelastic polymers and amorphous copolymers and terpolymers for elastomers. EXAMPLE 12 A titanium catalyst containing MgCl2 was prepared by dry ball milling 4 days a mixture of anhvdrous MgCl2 (1 mole), TiCl4 (1 mole) and #-TiCl3 (0.1 mole). Propylene was polymerized using the conditions in Example 11, Run B and the quantities shown in Table VII. Activity with the cocatalysts of this Invention (Run L) was intermediate tween those of the AlEt3 and AlEt2Cl controls (Runs J and v but the stereospecificity as shown by %HI was much higher than tne controls. The large increase in %HI I obtained with this MgCl2-containing catalyst is in contrast to the results i Example 1 using TiC13 catalysts in which activity increased sharply but %HI decreased. TABLE VII Alkyl Rate Run Catalyst Metals g/g Cat/hr % HI J(Control) 1 10 AlEt3 79 54.4 K(Control) 1 10 alEt2Cl 18 35.8 L 0.2 1 AlEtCl2 + 42 81.0 1 (s-Bu)2Mg XAMPLE 13 A titanium catalyst was prepared by dry ball milling 4 days a fixture of 5 MgCl2, 1 TiC14 and 1 ethyl benzoate, heating a slurry of the solids in neat TiCl4 2 hours at 800C., washing with n-heptane and vacuum drying. The catalyst contained 3.78% Ti. Propylene was polymerized following the procedure of Example 11, Run B except that supported catalyst was used. As shown in Table VIII, all the control runs (M through S) gave substantially lower activity and/or %HI than the AlwtC12 + s-Bu2Mg combination (Run T) or AlCl3 + s-Bu2Mg (Run U). If the new cocatalysts simply reacted as the separate alkyl metal compounds, the results should have been like Runs M + Q. If the new cocatalysts simply reacted according to the equation: AlRCl2 ' R2Mg AlR2Cl + RMgCl, then the results should have been like Runs N + P. However, the results in Run T and U are dramatically better, showing the completely unexpected formation of R2AlR' as previously defined. A much smaller synergistic effect was obtained by combining AlEt2Cl + s-Bu2Mg (Run S), but the results were poorer tan those obtained with AlEt3. Combining s-Bu2Mg with AlEt3 (Run R) destroyed the activity shown by AlEt3 alone (Run o). Thus, the outstanding results were obtained only when R2Mg was combined with RAlCl2 or AlCl3. TABLE VIII Mmoles Mmoles Time Rate Run Catalyst Al Cpd Mg Cpd Hrs. g/g Cat/hr % HI M(Control) 0.2 1 AlEtCl2 -- 0.5 0 - N(Control) 0.2 1 AlEtCl2 -- 1 47 61.1 O(Control) 0.2 1 AlEtCl2 -- 1 326 82.6 P(Control) 0.2 -- 0.83 s-Bu MgCl 0.25 0 - Q(Control) 0.2 -- 0.83(s-Bu)2Mg 0.25 0 - R(Control) 0.2 1 AlEt3 0.83(s-Bu)2Mg 0.25 -- - S(Control) 0.2 1 AlEt2Cl 0.83(s-Bu)2Mg 1 165 80.5 T 0.2 1 AlEtCl2 0.83(s-Bu)2Mg 1 367 91.9 U 0.2 1 AlCl3 0.83(s-Bu)2Mg 1 220 88.9 EXAMPLE 14 The procedure of Example 13 was followed using 0.2g of the supported TiC14 catalyst together with (s-Bu)2Mg and variations aluminum compounds. TABLE IX Mmoles Mmoles Time Rate Run A1 Cpd (s-Bu)2Mg Hrs. g/g Cat/hr % HI V 0.4 A1EtCl2 0.33 1 60 94.5 W 1 A1EtCl2 0.41 1 64 76.6 X 0.5 A1EtCl2 0.83 1 260 87.2 Y 0.5 AlCl3 0.83 2 136 90.7 Z 1 A1EtCl2 + 1 AlEt2Cl 0.83 1 404 86.9 AA 0.4 AlEtBr2 0.83 1 220 88.9 BB 1 AlC8H17Cl2 0.83 1 425 88.0 CC 0.63 EtC1A1N(iPr)2 0.53 1 6 - DD 1 Br2A1N(iPr)2 0.83 1 16 -- Comparisons of Runs V, W, and X shows that the highest %HI is obtained at approximately equimolar amounts of RAlCl2 and R2Mg (Run V), that a large excess of RAlCl2 is undesirable (Run W) and that a small excess of R2Mg increase activity (Run X). Activity also increased upon addition of AlEt2C1 to the AlEtCl2-(s-Bu)2Mg system (Run Z). The remainder of the experiments show that the dibromide may be used in place of chloride (Run AA), that long chain alkyl aluminum compounds are very effective (Run BB), but that dialkyl amide groups on the aluminum compound destroy catalyst activity (Runs CC and DD). EXAMPLE 15 The procedure of Example 13, Run T was followed except that Lewis bases were also added to the AlEtCl2- (s-Bu)2Mg cocatalysts. Addition of Lewis bases causes a decrease in catalyst activity until it becomes zero at a mole ratio of one strong base per mole of RA1C12 + R2Mg (Table X). TABLE X Rate Run Mmoles Base/8sec-Bu)2Mg Time, Hrs, g/g Cat/hr %HI EE 0.24#COOEt(a) 0.5 174 94.3 FF 0.5 EtN(b) 1 62 85.5 GG 2 Diisopentyl ether 1 127 78.8 HH 2 Tetrahydrofuran(c) 1 0 - (a) Added to the (s-Bu)2Mg. (b) Premixed total catalyst in 100 ml n-heptane at 65 C., 5min. before adding Et3N. (c) Added to premixed AlEtCl2-(s-Bu)2Mg. As shown in Run E, small auantities of Lewis base are effective in improving isotacticity (94.3% HI vs. 91.9 in Run T) while maintaining high activity (nearly 9 times the conventional AlEt2Cl/TiC13-0.33 AlCl3 catalyst, Example 11, Run H). EXAMPLE 16 The procedure of Example 13, Run T was followed except that xylene diluent was used for polymerization insteat of n-heptane. Activity was 676 g/g Cat/hr and the polymer gave 90.98 heptane insolubles. The polymer was precipitated with 1 liter isopropyl alcohol, filtered, driec and analyzed for metals. Found 13 ppm Ti and 83 ppm Mg. Thus at high monomer concentration and longer polymerization times the high efficiency would yield verv low catalyst residues without deashing. EXAMPLE 17 The procedure of Example 13, Run T was followed except that polymerization was carried out at 500C. and 800C Both polymerization rate and % HI decreased with Increasing temperature, with the largest decrease taking place above 650C. (Table XI). m XI Polymer Time Run Temp. C. Hours Rate %HI II 50 1 474 90.4 T 65 1 367 91.9 JJ 80 0.5 148 74. b EXAMPLE 18 Propylene was polymerized at 690 kpa pressure in a stirred autoclave at 50 C, 1 hour. A second preparation of MgCl2-containing TiCl4 catalyst (2.68 Ti), made as in Example 13 except that TiCl4-ethylbenzoate complex was preformed, was used in combination with AlRCl2-R2Mg. Hig stereospecificity was obtained at high rates and catalyst efficiencies (Table XII). TELE XII g Mmoles Mmoles Run Cat. AlEtCl2 (s-Bu2)Mg Rate % HI KK 0.10 0.5 0.5 1672 88.8 LL 0.10 0.25 0.25 696 95.0 EXAMPLE 19 The procedure of Example 13, Run T was followed except that the catalyst of Example 18 was used and 1 mmole di-n-hexyl magnesium was used instead of 0.83 minole (s-Bu)2Mg. The (n-hexyl)2Mg in Soltrol #10 was obtained from ethyl Corporation (Lot No. BR-516). Polymerization rate was 551 g/g Cat/hr but the polymer gave 76.9% EI which unnacceptable. Thus n-alkyl magnesium compounds do not yield the high stereospecificity of the secondary and tertiary alkyl compounds of this invention. EXAMPLE 20 The procedure of Example 15 Run EE was followed except that a new pure sriple of (sec-Bu)2Mg was used with 0.33 mole diethyl ether instead of ethyl benzoate and the reaction time was 1 hr. Rate was 268 g/g Cat/hr and % HI = 92.2. EXAMPLE 21 A catalyst was prepared by dry ball milling 4 days a mixture of 10 MgCl2, 2 TiC14, 2 ethylbenzoate and 1 Mg powder, heating the solids in neat TiCl4 2 hours at 800C., washing with n-heptane and vacuum drying (Ti = 2.16%). Propylene was polymerized 1 hour at 650C. and atmospheric pressure using 0.20 g c this catalyst under the conditions of Example 13, Run T except only 0.4 mmole (s-Bu)2Mg and 0.4 mmole AlEtCl2 was used. Rate was 240 g/g Cat/hr and % HI = 93.9. EXAMPLE 22 A catalyst was prepared by dry ball milling 1 day a mixture of 5 MgCl2 and 1 ethylbenzoate, adding 1 TiC14 and milling an additional 3 days, then treating the solids with neat TiCl4 2 hours at 800C., washing with n-heptane and vacuum drying (3.44 % Ti). Propylene was polymerized following the procedure of Example 13, Run T, except that 1 mmole (s-Bu)2Mg was usf instead of 0.83 mmole; Rate was 298 g/g Cat/hr and W HI = 89. EXAMPLE 23 Following the procedure in Example 18, two catalysts were made at different Mg/Ti ratios. Catalyst A was made with 1 MgCl2 + 1 TiCl4-ethylbenzoate and B (2.10% Ti) was made with 10 MgCl2 + 1 TiCl4-ethylbenzoate complex. Propylene was polymerized following the procedure of Examp 13, Run T (Table XIII). TABLE XIII g Mmoles Mmoles Run Cat AlEtCl2 (s-Bu)2Mg Rate % HI MM 0.107A 2 1.66 60 72.0 NN 0.316B 0.25 0.25 512 60.4 00(a) 0.316B 0.25 0.25 124 84.2 (a) Added 0.25 mmole triethylamine to the alkyl metal cocatalysts. These results show that the 1:1 and 10:1 riC14 catalyst preparations were not as effective as the 5:1 preparations in preceding examples. EXAMPLE 24 Polvmerizations were carried out in a 1 liter baffled resin flask fitted with a reflux condenser and stirrer. In a standard procedure for propylene polymer- izations, 475 ml n-heptane ( 1 ppm water) containing the alkyl metal cocatalysts was charged to the reactor under 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 200-500 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 MgCl2, 1 TiCl4 and 1 ethylbenzoate, dry ball milling 4 days, heating a slurry of the solids it neat TiCl4 2 hours at 80 C., washing with n-heptane and vacuum drying. The catalyst contained 3.785 Ti. Portions of this catalyst preparation were used in the experiments shown in Table XIV. Various control runs are shown for comparison wit 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-nu2Mg determined by titration. IR, NMR and GC analyses showed the presence of butoxide groups and 0.07 mole d- ethyl 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. 1 TABLE XIV 2 (0.2 g Catalyst, 500 ml n-C7, 65 C., 1 hr.) 3 Mmoles Mmoles Mmoles Rate 4 Run Al Cpd Mg Cpd Base g/g Cat/hr % HI 5 Control 1 AlEt2Cl -- -- 47 67.1 6 Control 1 AlEt3 -- -- 326 82.6 7 Control 1 AlEt2Cl 0.83 (s-Bu)2Mg -- 165 80.5 8 Control 1 AlEt3 0.83 (s-Bu)2Mg -- 6 -9 Control -- 0.83 (s-Bu)2Mg -- 0 -10 Control -- 0.83 s-BuMgCl -- 0 -11 A 1 AlEt2Cl 1 s-Bu Mg OOC# -- 165 95.2 12 B 1 AlEt2Cl 1 s-Bu Mg OC15H31 -- 276 91.7 13 C 1 AlEt2Cl 1 s-Bu Mg OC2H5 -- 261 91.4 14 D 1 AlEt2Cl 1 s-Bu Mg SC12H25 -- 310 93.2 15 E 1 AlEt2Cl 0.83 s-Bu MgCl 1 Et3N 100 94.6 16 F 1 Et2AlOOC# 1 s-BuMgCl -- 351 90.5 17 + 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 25 A second catalyst preparation 2.68% Ti was made following the procedure of Example 24 except that a preformed 1:1 complex of TiCl4##COOEt was used. In Runs G and H, the s-BuMgCl#Et2O was obtained by vacuum stripping an ether solution of the Grignard reagent. In Run I, the n + s BuMgOOCC6H5 was made by reacting pure (n + s Bu)2Mg with benzoic acid. Propylene polymerizations were carried out as in Example 24 (Table XV). TABLE XV Mmoles Mmoles Mmoles Rate Run Al Cpd Mg Cpd Base g/g Cat/hr. % HI G 1 AlEtCl2 1 s-BuMgCl 1 Et2O O - H 1 AlEt2Cl 1 s-BuMgCl 1 Et20 132 93.1 I 1 AlEt3 1 n + s-Bu -- 123 89.7 MgOOCC6H5 Run G shows that monoalkyl aluminum compounds arenot effective in combination with the mono-organomagnesium compounds in this invention. In contrase, Example 13, Run T, 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 with monoalkyl magnesium compounds. EXAMPLE 26 Propylene was polymerized at 690 kPa pressure in a 1 liter stirred autoclave at 500C. for 1 hour using the supported TiCl4 catalyst of Example 25 (Table XV). The Mg compound was made as in Example 24, Run A. TABLE XVI g Mmoles Run Cat. Mmoles Mg Cpd AlEt9Cl Solvent Rate % HI J 0.05 0.5 s-BuMgOOC# 0.5 n-C7 1292 89.9 K 0.10 0.4 s-BuMgOOC# 0.4 n-C7 317 96.9 L 0.10 0.4 s-BuMgOOC# 0.4 xylene 517 96.5 Comparison of Runs J and K shows that the lower alkyl metal/catalyst ratio o in K gave higher heptane in solubles. Run L in xylene diluent gave higher activity than K in heptane. EXAMPLE 27 The procedure of Example 25 was followed except that organomagnesium compounds containing alkoxy and benzoate groups were used in combination with A1Et2Cl together with diethyl ether. The s-BuMgOsBu was prepared by reactin a dilute solution of sBu2Mg containing 0.33 Et20 with one mole s-3uOH and used without isolation (Run M). The mixtur in Run N was prepared in a similar manner by reacting 1.55 mmole n + s Bu2Mg with 1.10 s-butanol, adding 0.066 Et2O, then adding this product to a solution of 1 benzoic acid in 275 ml n-heptane. TABLE XVII Mmoles Mmoles Run Mmoles Mg Cpd AlEt2Cl Et2O Rate % Hi M 1 s-BuMgOs-Bu 1 1/3 107 94.6 N 0.45 n+s BuMgOOC# 0.066 0.066 101 95.9 0.55 n+s BuMgOsBu 0.35 s-BuOMgOOC# Comparison with Example 25, Run E shows that superior results were obtained wit smaller amounts of diethyl ether by using alkoxide and carboxylate salts instead of the chloride. C. EXAMPLE 28 The procedure of Example 7, Run Z was followed except that 0.25 mmole Mg(OOCC6H5)2 was used in place of acetophenone as the third component. The magnesium benzoate was prepared from a dilute heptane solution of benzoic acid and n+ s Bu2Mg. The t-Bu2AlEt was added to the milky slurry of Mg(OOCC6H5)2, charged to the reactor and heated to 650C., 5 min,. after which the supported titanium catalyst was added. The propylene polymerization rate was 122 g/g Cat/hr and polymer HI - 97.7%.- EXAMPLE 29 The procedure of Example 6, Run P, was followed except that magnesium benzoate was used as a cocatalyst modifier. The magnesium salt was made in situ by reacting a hydrocarbon solution of (n + s-Bu)2Mg with two moles of benzoic acid. The salt slurry was reacted with the alkyl metal cocatalyst in 500 ml n-heptane at 250 to 650C. to obtain a soluble product before the catalyst was added. TABLE XVIII Mmoles Mmoles Run Al Cpd Mg(OOC0)2 Rate % HI A(Control) 1 AlEt3 s 241 82.3 B 1 AlEt3 0.25 210 93.0 C 1 AlEt3 0.50 0 - D(Control) 1 t-Bu2AlEt -- 248 93.8 E 1 t-Bu2alEt 0.25 125 97.7 When used in small amounts relative to the aluminum trialkyl cocatalyst, the magnesium benzoate sharply increased stereospecificity as measured by the percent boiling heptane insolubles (Runs B and E vs. A and D). Activity decreased somewhat, but the results for both rate and % HI were superior to those of conventional tiCl3 catalysts (Example 11, Runs A, C, F, and S). At a ratio of 0.5 Mg(OOC0)2 to AlEt3, the catalyst was Inactive (Run C). The modifier was effective with both types of aluminum trialkyls, but it gave the highest stereospecificity with the novel trialkyl aluminum cocatalysts of this invention. EXAMPE 30 The procedure of Example 29, Run B, was followed using various metal carboxylates as cocatalyst modifiers. TABLE XIX Run Mmoles Salt Rate % HI F 0.25 Mg acetate 175 94.7 G 0.25 Mg neodecanoate 235 91.8 H 0.25 Na stearata 206 92.4 I 0.25 K neodecanoate 211 90.8 Comparison with control Run A, Example 29, shows that much higher % HI was obtained while still retaining high avctivity. EXAMPLE 31 The procedure of Example 29 was followed except that various dialkyl aluminum carboxylates were used instead of the magnesium salt. The aluminum trialkyl and carboxylate were premixed 3-5 minutes at 25 C. in 30 ml n-heptanes. TABLE XX Run Mmoles Al Cod Mmoles Carboxylate Rate % HI J 1 AlEt3 1 Et2AlOOC0 130 97.4 K 1 AlEt3 1 s-Bu2AlOOC0 232 95.5 L 1 s-Bu2AlEt 1 Et2AlOOC0 246 94.4 M 1 s-Bu2AlEt 1 s-Bu2AlOOC0 276 91.4 N 1 AlEt3 1 Et2AlOOCC6H3Me2-2,6 262 89.1 O 1 s-Bu2AlEt 1 Et2AlOOCC6H3Me2-2,6 310 77.7 P 1 AlEt3(a) 1 Et2AlOOC0(a) 70 97.8 Q 2 AlEt3(b) 1 Et2AlOOC0(b) 239 93.1 R -- 1 s-Bu2AlOOC0 O - (a) Premixed 5 minutes in 30 ml n-heptane at 40-50 C. (b) Premixed in 30 ml n-heptane at 60 C, 30 minutes. Comparison witn control Run A, Example 29, shows that increased stereospecificity was obtained with all o the alkyl aluminium carboxylates except in Run 0. Higher activities were else obtained In some cases, especially with the s,6-dimethylbenzoates (Runs N and 0). The ortho substituents are believed to hinder the carboxyl addition reaction which leads to lower activity by consumption of the aluminium trialyl. Support for this type of side reaction can be seen in the low activity in Run p, premixed in concentrated solution, compared to Run Q which was tre- mixed in 500 ml n-heptane. When sufficient excess AlR3 is used in a concentrated premix with the aluminium benzoate, one regains activity, but the modifier is presumed to be the aluminium alkoxide products from the carbonyl addition reaction. Run R shows that the carboxylate compound alone is not a cocatalyst, so that the improved results obtained when mixted with AlR3 must be due to the reaction of the AiR3 with the carboxylate modifier. EXAMPLE 32 The procedure of Example 29 was followed except that tertiary butyl aluminum compounds were used and the ratio of aluminum trialkyl to aluminum benzoate was varied. TABLE XXI Run Mmoles Al Cpd Mmoles Carboxylate(a) Rate % Hi S 1 t-Bu2AlEt 0.25 t-Bu2AlOOC0 221 93.4 T 1 t-Bu2Alet 0.50 t-Bu2AlOOC0 227 94.8 U 1 t-Bu2AlEt 1.0 t-Bu2AlOOC0 184 94.6 (a) May contains some t-Bu EtAlOOC0 as it was prepared by reacting t-Bu2AlEt with 0COOH. Comparison with Example 29 shows that the dialkyl aluminum benzoates were not as efficient as magnesium benzoate, and higher ratios were needed to achieve higher stereospecificity. EXAMPLE 33 The procedure of Example 6, Run P, was followed except that dialkyl aluminum alkoxides were used as cocatalyst modifiers. TABLE XXII Run Mmoles Al Cpd Mmoles Carboxylate(a) Rate % Hi V 0.8 t-Bu2AlEt 0.2 t-Bu2AlOCMeEt0 196 94.2 W 0.8 t-Bu2AlEt 0.2 t-Bu2AlOCEt0 191 94.6 X* 1 AlEt3 -- 506 81.6 Y* 1 AlEt3 10 Et2AlOC15H31 113 95.5 * Another catalyst preparation was used (contained 3.167. Ti). Comparison of Runs V and-W with control run D, Example 29, shows that the alkoxide additives increased stereospecificity as measured by heptane insolubles. This was also true for Run Y versus its control (Run X). In this case, a large excess of alkoxide was used relative to the A1R3. These results are opposite to those using unsupported TiCl3 catalysts in which it is known that dialkyl aluminum alkoxide cocatalysts produce low heptane insoluble products. EXAMPLE 34 The procedure of Example 33 was followed using another catalyst preparation having 3.38% Ti and using a hindered Lewis base in place of the'Al alkoxide. TABLE XXIV tholes Run AlEt3 Mmoles Hindered Base Rate * HI E 1 2 Tetramethyl TES (1) 277 94.1 F 1 1 Tetramethylpiperidine (2) 402 95.5 G 1 2 i Pr2NEt 289 95.3 H 1 1 Di-tolylamine 309 93.4 Mmoles Unhindered Base Control 1 1 MeOt-Bu 129 91.3 Control 1 1 Met-BuNE 11 95.5 Control 1 1.06 Et3N 38 97.0 Control 1 1 2,6-Di-t-butylpyridine 487 84.8 (1) 2,2,5,5-tetramethyltetrahydrofuran. (2) 2,2,6, 6-tetramethylpiperidine. Comparison with Control Run Z of Example 34 shows that the hindered bases (Runs E-H) gave both high activity and high HI, whereas the control runs with unhindered bases gave improved HI but with a serious loss of activity. The completely hindered 2,6-di-t-butylpyridine had little effect on either rate or HI. EXAMPLE 35 The procedure of Example 34 was followed except that the catalyst preparation of Example 33, Run X, was used TABLE XXV voles Run AlR3 Mmoles Hindered Base Rate 8 HI I 1 AlEt3 1 Diphenylamine 233 95.6 J 1 AlEt3 2 Tetramethylpiperidine 292 97.1 K 1 sBu2AlEt 1 Tetramethylpiperidine 302 95.0 L 1 i Eu3 Al 1 Tetramethylpiperidine 423 97.1 Mmoles Unhindered Base Control 1 sBu2AlEt 1 2,6-Dimethylpiperidine 4 85.4 Control 1 AlEt3 1 Ethylbenzoate O - Control 5 AlEt3 4 Tetrahydrofuran 100 83.0 Comparison with Control Run X of Example 33 shows that the hindered based gave both high activity and high HI, whereas the unhindered bases gave both low activity and HI. Since many modifications and variations of this invention may be made without departing from the spirit or scope of the invention thereof, it is not intended to limit the spirit or scope thereof to the specific examples thereof

Claims: CLAIMS: 1. A catalyst composition which comprises a mixture of: (a) at least one alkyl metal compound having the formula R"'3M, wherein M = Al, Ga or'In, R"' is a C1 to C20 primary, branched primary, secondary, or tertiary alkyl, cycloalkyl, alkenyl or aralkyl group or hydrogen or a mixture thereof, the molar ratio of said R"'3M to said transition metal compound being 0.5:1 to 200:1; (b) a titanium metal compound on a support, said titanium metal compound being TiC13, TiC14, TiBr3, TiBr4 or a mixture thereof; and (c) at least one hindered Lewis base, said Lewis base not causing excessive cleavage of metal-carbon bonds or loss of active sites, said Lewis base complexing ability towards said R3"'M being hindered sufficiently by steric and/or electronic effects to cause appreciable dissociation of the complex of said R3'11M and said Lewis base under polymerization conditions. 2. A composition according to claim 1 wherein said titanium compound is TiC14 or TiC13. 3. A composition according to either of claims 1 and 2 wherein said support is MgC12 4. A composition according to any one of the preceding claims wherein said Lewis base is a piperdine, a pyrrolidine, a ketone, a tetrahydrofuran, a secondary or tertiary aromatic amine or a tertiary aliphatic amine. 5. A composition according to any one of claims 1 to 3 wherein said Lewis base is 2,2,6,6-tetramethylpiperidine,2,2,5,5-tetramethylpyrrolidine, 2,2,5,5-tetramethyltetrahydrofuran, di-tert-butylketone,2-6-diisopropylpiperidine, ortho-tolyl t-butylketone, methyl 2,6-di-tert-butylphenylketone, diisopropylethylamine, t-butyl-dimethylamine, 6-methyl-2- isopropylpyridine, diphenylamine, di-ortho-tolylamine, N-N-diethylaniline, or di-ortho-tolylketone. 6. A composition according to any one cf the preceding claims wherein said R3""M contains at least one of said alkyl groups having 2 to 4 carbon atoms.

Inventors: LANGER, ARTHUR WALTER JR.
Applicants: EXXON RESEARCH AND ENGINEERING COMPANY
Application year: 1980
Main classification: C08F10
IPC codes: C08F10, C08F4