IE41546B1 - Catalyst composition for polymerization of conjugated dienes - Google Patents

Abstract

1516861 Catalyst for the polymerization of conjugated dienes MICHELIN ET CIE (COMPAGNIE GENERALE DES ETABLISSEMENTS MICHELIN) 4 June 1975 [5 June 1974] 24148/75 Heading C3P [Also in Division C2] A catalyst for the homopolymerization of conjugated dienes or copolymerization thereof with an aromatic vinyl compound consists of (a) lithium or an organo-lithium compound, (b) a compound of barium or strontium and (c) an organometallic compound of a metal of Group IIB or IIIB of the Mendeleef Periodic Table. The polymers formed have a high trans content and low content of 1,2 linkages. In the examples butadiene or isoprene are homopolymerized or copolymerized with styrene or butadiene is copolymerized vinyl toluene or t-butyl styrene in cyclohexane, heptane or toluene using as catalyst n-butyl lithium; cinnamone or dibenzoylmethane barium, barium acetylacetonate, hydride, naphthenate or nonyl phenate and aluminium triethyl,-diethyl chloride,-ethyl dichloride or-ethyl sesquichloride or diethyl zinc.

Description

The invention relates to homopolymerization of conjugated dienes or copolymerization of conjugated dienes either with one another, or with aromatic vinyl compounds to prepare polymers having a very low content of 1,2- or 3,4- linkages and having a high content of trans-1,4 linkages, and an elastomeric character.

The invention also relates to a catalytic composition for use in the polymerization, reactions.

Dienes polymers can be prepared in solution in hydrocarbons with a high degree of stereospecificity e.g. high contents of cis-1,4 linkages for example polybutadiene and polyisoprene, or of trans1,4, or again 1,2- or 3,4-linkages. The polymers with a high content of trans-1,4 linkages, i.e. greater than 95# as thus prepared have a very strong tendency to crystallisation at ordinary temperatures. They behave more like plastics materials than elastomers and for this reason they cannot be used as the principal component of a mixture used for the manufacture of elastic objects, particularly pneumatic tyres.

Homopolymars of conjugated dienes and copolymers of conjugated dienes with one another or with aromatic vinyl compounds when prepared in a hydrocarbon medium using a catalytic system containing lithium do not possess a high degree of steric purity. In point of fact, with lithium catalytic systems the homopolymers and copolymers obtained having viscosities of the order of 2 or 3, have a content of 1,2- or 3,4-linkages on the diene part of the polymer which is greater than 6#, and a content of trans-1,4 linkages which is less than 60#. For example polybutadienes and the copolymers of butadiene contain: 4154 6 to 55% of trans-1, 4 linkages 7 to 12% of 1,2 linkages; and 40 to 45% of cis-1,4 linkages; while polyisoprenes and copolymers of isoprene contain: to 25% of trans-1,4 linkages, to 10% of 3,4-linkages, and to ' 85% of cis-1,4-1inkages, For higher viscosities, i.e. at least equal to 6, particularly in 10 the case of isoprene copolymers, the content of cis-1,4 linkages increases up to 95% at the expense of trans-1,4 and 1,2- or 3,4-linkages With lithium catalyst systems it is possible to increase, within the above limits, the proportions of 1,2- or 3,4-linkages in relation to 1,4-linkages by, for example, modifying the polarity of the reaction medium. It has not been possible, however, to vary within a wide range the content of 1,4-trans linkages whilst maintaining the content of 1,2 or 3,4-linkages at a very low level.

It is, therefore, an object of the present invention to obtain diene homopolymers or copolymers having a high content of 1,4-trans linkages in the diene parts of these polymers, either over the entire length of the homopolymer or copolymer chain or over only a part of this length, while at the same time keeping a low content of 1,2- or 3,4-linkages.

Therefore, according to one aspect of the invention there is provided a catalyst composition suitable for use in the homopolymerization or copolymerization of olefins consisting essentially of a lithium initiator (as herein defined), and a co-catalyst containing a compound of barium or strontium and an organometallic compound of a metal of Group IIB or IIIA of the Periodic Table.

According to another aspect there is provided a process forsthe homopolymerization of conjugated dienes or the copolymerization of conjugated dienes with one another or with one or more aromatic vinyl compounds in which the monomers are reacted in the presence of a catalyst composition consisting of an organo-lithium initiator and of a composite co-catalyst containing a compound of barium or strontium and an organo-metallic compound of a metal (indluding boron) of Group IIB or IIIA of the Periodic Table. References to the Periodic Table herein refer to the Table on Page B3 in the Handbook of Chemistry and Physics 47th Edition published by the Chemical Rubber Company.

Using this catalyst composition and process of the invention it is possible to manufacture homopolymers of conjugated dienes and copolymers of conjugated dienes with one another, or with one or more aromatic vinyl compounds which are rich in trans-1,4 linkages and with a low content of 1,2 or 3,4 linkages.

These diene polymers are elastomers and are useful in the production of rubber compositions which have good green strength before vulcanisation and good strength properties after vulcanisation.

By lithium initiator as used herein means any organo-metallic compound containing one or more carbon-lithium bonds, any ionicradical adduct of lithium and multi-ring aromatic hydrocarbons and metallic lithium itself.

Examples of suitable organo-lithium initiators include the alkyl aliphatic organo-lithium compounds, such as ethyl lithium, n-butyl . lithium, isobutyl lithium, sec-butyl lithium, ter-butyl lithium, isopropyl lithium, n-aniyl lithium and isoamyl lithium, the alkenyl organo-lithium compounds such as allyl lithium, propenyl lithium and isobutenyl lithium, the living polymers polybutadienyl lithium, polyisoprenyl lithium, and polystyryl lithium, dilithium polymethylenes such as 1,4-dilithiobutane, 1,5-dilithiopentane and 1,20-dilithioeicosane, aromatic organo-lithium compounds such as benzyl lithiu, phenyl lithium and 1,1-dipehenyl-methyl lithium, the polylithium compounds resulting from the reaction of metallic lithium with aryl-substituted ethylenic compounds, such as 1,1diphenyl ethylene, transstilbene and tetraphenylethylene, and the radical ions such as lithium naphthalene, lithium anthracene, lithium chrysene and lithium diphenyl. Derivatives of the latter radical ion compounds substituted by one or more alkyl groups are also suitable as initiators. Oligomers of conjugated dienes or substituted styrenes containing lithium are also suitable as initiators.

Suitable compounds of barium or strontium forming part of the cocatalyst include the hydrides HgBa and H^Sr, the salts of mono or dicarboxylic organic acids of the formulae (R-COO),, Ba or 1 Sr, R—(COO)g Ba or Sr in which R and R are organic radicals, the former monovalent, the latter divalent, and the corresponding thio-acids, the monofunctional or polyfunctional alcoholates and the corresponding thiolates, the monofunctional or polyfunctional phenates and the corresponding thiophenates, the barium or strontium salts of acid alcohols and acid phenols and the corresponding thio-products and the beta-diketonates of barium or of strontium such as the products of the reaction of barium or strontium with acetylacetone, dibenzoylmethane, benzoyltrifluoroacetone and benzoyl acetone. Other suitable organic derivatives of barium or strontium include those of 1,1-diphenylethylene, 1,2-acenaphthylene, tetraphenyl butane, or alphamethyl-styrene, or again those such as diphenyl barium or strontium, biscyclo-pentadienyl barium or strontium, the trialkyl silyls of barium or strontium and barium or strontium triphenyl silys, the mixed organic derivatives such as phenyl barium iodide, methyl strontium iodide and the barium or strontium salts of secondary amines, the barium or strontium ketyls i.e. a compound containing a single ketone group such as barium or strontium benzophenone, barium or strontium cinnamone, and corresponding alkylated products as well as the sulphided homologues i.e. analogous compounds containing the group X=S, and barium and strontium naphthalene, anthracene, chrysene and diphenyl. 2o Representative examples of organo-metallic compounds of Group IIB or IIIA are the zinc or cadmium dialkyls such as diethyl zinc and diethyl cadmium, organo-aluminium compounds which may or may not be halogenated such as triethyl aluminium, triisobutyl aluminium, diethyl aluminium chloride, ethyl aluminium dichloride, ethyl aluminium sesquichloride and methyl aluminium sesquichloride, and dialkyl aluminium hydrides such as diethyl aluminium hydride and diisobutyl aluminium hydride.

The constituents of the catalyst composition may be conveniently uo dissolved or suspended in a hydrocarbon solvent for use. A preferred composition comprises Δ- butyl lithium as the lithium initiator and barium phenate and a trialkyl aluminium as the cocatalyst.

The co-catalytic system containing a compound of barium or strontium if and an organo-metallic compound of a metal of Group IIB and IIIA may be formed according to the two following preferred variants; Accordng to the first variant, the constituents of co-catalytic system are dissolved separately in a hydrocarbon solvent which is preferably identical with that which is to be used subsequently during the homopolymerization or copolymerization reaction, the separate constituents then being able to be added separately to the reaction. - 8 According to the second variant the co-catalyst is pre-formed by mixing the barium of strontium compound and the organometallic compound of the metal of Group IIB or IIIA in a hydrocarbon solvent. These pre-formed co-catalysts are noteworthy in that they are more soluble in hydrocarbon solvents and in that they preserve their high activity for long periods. In this mixture of the two constituents of the co-catalyst, there is total or partial solubilisation of the barium or strontium compound, and in particular of those which are normally insoluble in hydrocarbon media, such as the hydrides, the acetylacetonates and most of the alcoholates. The result is that in this way the use of the pre-formed co-catalyst system is particularly easy.

According to the first variant, the components of the co-catalytic system dissolved in the hydrocarbon solvent are introduced separately into the reaction medium,either at the beginning of the reaction at the same time as the organo-lithium initiator so as to form the soluble catalytic composition in situ, or during the polymerization jointly in small quantities or in one go, or again one after the other in either order. This mode of operation is suitable for the barium or strontium compounds which are soluble in the solvents concerned.

An increase in the content of trans-1,4 linkages and a decrease in the content of 1,2 or 3, 4 linkages of the resulting polymer is achieved when the whole of the co-catalyst and the lithium initiator has reacted. Thus, when the whole of the co-catalytic system is present right from the beginning of the polymerization reaction, one obtains products with a very high content of trans-1,4 linkages and with a very low content of 1,2 or 3,4-linkages over the entire length of the homopolymer or copolymer chain. On the other hand, when the constituents of the co-catalytic system are introduced during the reaction, either jointly in small quantities, or one after the other, it is possible to prepare polymers which have several sequences and which possess different stereo configurations, the addition of the co-catalytic system having the result of the formation of sequences which are rich in trans-1,4 linkages and poor in 1,2- or 3,4-linkages.

When one uses the co-catalytic system in the pre-formed form it is possible to add it to the organo-lithium initiator either at the commencement of the reaction so as to obtain a product with a constant content of trans-1,4 linkages from one end to the other of the macromolecular chains, or during the reaction in one or more goes, according to whether one desires to have no modification of the stereo configuration except after this addition or if one desires to have the modification of the configuration in a gradual form.

The catalytic system according to the invention has good activity over a wide range of concentrations of catalyst and relative proportions of the components of the catalytic system.

According to the conditions under which the reaction takes place, e.g. the nature of the solvent or monomer or monomers present, or the temperature, the molar ratios between each of the constituents of the co-catalytic system and between one of the latter with the lithium initiator may be varied so as to obtain desired contents of trans-1,4 and 1,2-linkages. It is therefore necessary to choose these various molar ratios according to the conditions under which one operates to obtain the the desired stereo configurations of the polymer products. In this way, for example, one can vary the trans-1,4 linkage content from 45 to 95% and the 1,2- linkage content from 12 to 3% in the case of butadiene homopolymers or copolymers and the trans-1,4 linkage content from 10 to 45% and the 3,4-linkage content from 10 to 5% in the case of isoprene homopolymers or copolymers.

Thus, the optimum concentration for a constituent of the catalyst depends upon the concentration of the other constituents of the catalyst. However, one may assign certain limits to the different molar ratios between which one will achieve the optimum contents of trans-1,4 linkages and minimum contents for 1,2 or 3,420 linkages. These limits can be defined as follows: moles R3 Me IIIA or R2 Me IIB 0.2 <- < 10 mole of compound of Ba or Sr in which 0.25 and preferably: mole of compound of Ba or Sr < _;< 5 gram atom of Li moles R3 Me IIIA or R2 Me IIB 0.5 in which 0.5 in which R3Me IIIA mole of compound of Ba or Sr mole of compound of Ba or Sr _ < 1-5 gram atom of Li represents the organo-metallic compound of a metal 2 of Group IIIA and R Me IIB represents the organo-metallic compound of a metal of Group IIB.

By gram atom of lithium we mean the quantity of active organolithium compound used which represents the difference between the io total actually introduced and the minimum necessary to obtain initiation of polymerization, a quantity which serves inter alia to neutralise the residual impurities in the reaction media.

The polymer products obtained by a process in accordance with the invention have a very high content of trans-1,4 linkages and a low 15 contentof 1,2-or 3,4-linkageswhilstretaining an elastomer character - 12 for the polymer. According to one variant, a product with a high content of trans-1,4 linkages and a low content of 1,2- or 3,4-linkages over the entire length of the homopolymer or copolymer may be obtained, by introducing the catalytic composition at the commencement of the reaction. According to another variant, homopolymers and copolymers which possess different or even gradual sequences and stereo configurations may be obtained according to whether the constituents of the catalytic composition are added to the reaction medium in one or more goes either jointly or separately.

Representative examples of the dienes are the conjugated dienes 1,3butadiene isoprene, 2,3-dimethyl-l,3-butadiene, 1,3-pentadiene, 2,3methyl-pentadiene and 2,4-hexadiene.

Representative examples of the aromatic vinyl compounds are styrene, ortho-, meta-,para-methyl styrene or the commercial mixture known as vinyl toluene, the dimethyl and polymethyl styrenes, p-tert, butyl styrene, the vinyl naphthalenes, the methoxystyrenes, the halogenostyrenes, vinylmesitylene vinyldurene and di vinyl benzene.

The polymers products having the high content of trans-1,4 linkages prepared according to the invention are elastomers and so can be used in the production of rubber mixtures and so they are unlike other polymers with a very high content of trans-1,4 linkages prepared hitherto using different catalytic systems which are plastic and brittle at ordinary temperature because they are crystalline.

The mixtures of the polymers of the invention in the unvulcanised state possess, because of their high content of trans-1,4 linkages characteristics such as improved green strength, very high tensile strength and elongation at break, and better dimensional stability. These mixtures with improved properties are then capable of giving better rubbers which can be used in particular for the manufacture of tyres.

The invention will now be illustrated by the following Examples. Example I Copolymerisation of Butadiene/Styrene using n-Butyl Lithium/Cinnamone Barium/Triethyl Aluminium.

Preparation of the co-catalyst.

The cinnamone barium complex being soluble in toluene it has been possible to study the influence of each of the constituents of the co-catalyst, the ratio Ba/Al was varied using a constant amount of Ba.

The cinnamone barium complex was prepared in a 250 ml Steinie flask 415 46 under an atmosphere of rectified nitrogen, by dissolving 0.1 mole of cinnamone (1,5 diphenyl penta 1,4 diene 3 one) in 50 ml of tetrahydrofuran in which there were suspended 1,5 g of finely-divided metallic barium. (Rectified nitrogen is nitrogen of the quality that is commercially available from Air Liquide under the trade mark Nitrogen R). After agitating the mixture at ambient temperature for about 20 hours there was obtained a red solution which is filtered. This solution was evaporated in vacuo. The resultant reddish-brown deposit was taken up in toluene after two washings, in heptane, these operations being effected under an atmosphere of rectified nitrogen, so as to obtain a solution which was 0.025 M in the barium complex.

Copolymerization Two series of copolymerisation experiments were carried out by intro15 ducing into 250 ml Steinie flasks, as a catalytic system: -fi -variable quantities in the range of 0 to 200x10 moles, of triethyl aluminium, and -fi - 50x10 moles of active n-butyl lithium, as defined above.

In the first series, no barium compound was used. In each of the -6 flasks of the second series there were introduced 50x10 moles of barium cinnamone.

A copolymerization was carried out in the presence of cyclohexane - 15 (123 g per 250 ml Steinie flask) with 9.225 g of butadiene and 3.075 g of styrene per flask.

The reaction flasks were placed in a thermostatically controlled tank at 70°C, where they are agitated for a variable period of time so as to obtain samples corresponding to increasing conversion percentages.

The results obtained at 50? conversion are given in Tables IA and IB below which show respectively the results of the first series without barium and the second series with barium.

TABLE IA Moles of tri? ethyl AIxlO 0 (per Steinie flask) Time to obtain a rate of conversion of 50%(min) trans-1,4 1i nkages ( *) 1,2 1i nkages ( *) ?by weight of total styrene present in the copolymer 9 0 30 53 8 2 2.6 100 <30 54 8 2 1.2 200 < 30 54 8 2 0.9 TABLE IB Moles of triethyl AlxlO-6 (per Steinie flask) Time to obtain a rate of conversion of 50% (min) trans-1,4 linkages W 1,2 linkages (%) % by weight of total styrene present in the copolymer 9 0 300 54.0 9.0 16.0 2.0 25 210 62.5 6.0 12.5 1.6 50 150 75.0 4.0 11.5 1.3 75 105 80.0 3.5 9.0 1.1 100 90 78.0 5.5 7.5 1.0 200 50 76.0 6.0 5.5 0.9 On examining these results one can see the effect of each of the compounds introduced on the stereo configuration of the copolymers obtained (i.e. % of trans-1,4 and % of 1,2 linkages) and correspondingly on the kinetics of the reaction, the inherent viscosity attained and the mode of incorporation of the styrene. As regards the affect on the stereo configuration and particularly on the contents of trans-1,4 and 1,2 linkage one can see that the only obtains the desired effect when the three components of the catalytic system are all present together in the reaction medium; if one or other of them is absent, one obtains a stereo configuration which is fairly close to that obtained with n-butyl lithium used alone as a catalyst.

Example 2 Polymerization of butadiene with n-butyl lithium and a pre-formed co41546 - 17 catalytic system: barium acetylacetonate-trialkyl aluminium.

Preparation of the co-catalysts Barium acetylacetonate was prepared direct by the reaction of acetylacetone and baryta in an anhydrous methanol medium.

The product prepared was insoluble in hydrocarbons. A soluble co-catalytic system was obtained by mixing, under a rectified nitrogen atmosphere, for 15 minutes at ambient temperature, the barium acetylacetonate and trialkyl aluminium in the presence of a hydrocarbon solvent.

Three systems were prepared: System A: after 5.32 millimoles of barium acetylacetonate had been suspended in 170 g of normal heptane, 23.4 millimoles (0.92 M) of commercial triethyl aluminium were added to it. After agitation a clear solution was obtained having a content of 2,9x10 M of *2 barium and 11.3x10 M of aluminium.

System B: to 5.85 millimoles of barium acetylacetonate suspended in 170 g of toluene there were added 26.3 millimoles (0.92 M) of commercial triethyl aluminium. After agitation a clear solution with a content of 3.2x10 M of barium and 11.6x10 M of aluminium was obtained.

System C: to 5.58 millimoles of barium acetylacetonate suspended in 170 g of heptane were added 25.1 millimoles (0.79 M) of commercial triisobutyl aluminium. After agitation a clear solution with a -2 -2 content of 2.4x10 M of barium and 11.8x 10 M of aluminium was obtained.

Polymerization These three co-catalyst compositions were used in combination with normal butyl lithium to polymerize butadiene dissolved in heptane in a first series of experiments and in toluene in a second series of experiments.

Both series of experiments were effected in 250 ml Steinie flasks closed by a rubber stopper through which the various ingredients necessary for the polymerization were introduced. Into these flasks, under a pressure of rectified nitrogen (approximately 1 bar) there were introduced 123 g of solvent (heptane or toluene), 12.3 g of butadiene, then one of the above co-catalyst systems and finally the n-butyl lithium. The flasks were then placed in a thermostatically controlled tank at 60°C, where they were agitated for three hours.

After three hours, polymerization was stopped by the introduction into each flask of 0.25 ml of a solution of methanol in toluene containing 60 g per litre. Also introduced were 2 mis of a solution containing 240 g per litre of a phenolic anti-oxidant (Agerite Geltrol manufactured by the Vanderbilt Company).

The polymers were then recovered after coagulation by means of a metahnol/ acetone mixture and they were dried in vacuo in the stove at 80°C under a pressure of 0.2 bars for 15 hours.

For the samples thus obtained the conversion of butadiene to polybutadiene, the inherent viscosities at 25°C in a solution containing 1 g per litre in toluene and the stereo configurations were determined and the results obtained are set out in Table IIA and IIB which respectively relate to the first series of experiments using heptane and the second series of experiments using toluene.

TABLE IIA Co-catalyst system Active initiator n-BuLi (x 10 6moles) % conversion V trans-1,4 linkages W 1.2 linkages (%) Reference 50 100 2.4 51 8 Λ2χ10-6 moles Ba 66 54 1.6 77 4tA^Cl64xlO_t> moles Al 85 61 1.5 83 3 /rX45x10-6 moles Ba 41 59 1.8 73 4w£163x10-6 moles Al 77 71 1.6 82 4 £34xl0®moles Ba 45 56 1.7 73 4(C)£167xl0'6 moles Al 81 70 1.5 83 3 * In addition to the quantities indicated, which were counted as active, there were added additional quantities of n-butyl lithium intended to destroy the residual impurities of the reaction media TABLE IIB Co-catalyst system Active * initiator n-BuLi (x 106 moles % conversion V trans-1>4 linkages σ») 1,2 linkages (%) Reference 50 100 2.5 51 12 (A) 42X10-6 moles Ba 28 24 0.8 74 5 : 164x10 6moles Al 66 78 1.3 72 5 45x10~6 moles Ba 50 58 l.C 72 5 163xl0’6 moles Al 77 83 1.1 70 5 (qj 34x10-6 moles Ba 7 167X10-6 moles Al 50 40 1.0 76 5 86 70 1.2 78 5 * See above in connection with Table IIA.

Example 3 Polymerization of butadiene by means of n-butyl lithium and a preformed co-catalyst system: dibenzoylmethane barium - triethyl aluminium.

Preparation of the co-catalyst Dibenzoylmethane barium chelate was prepared directly from dibenzoy1 methane and baryta in an anhydrous methanol medium.

The product as prepared was insoluble in hydrocarbons. The co5 catalyst system was prepared by mixing, under an atmosphere of rectified nitrogen, suspended in 123 g of heptane, 5.2 millimoles of dibenzoylmethane barium and 26 millimoles (0.84 M) of commercial triethyl aluminium. This mixture was brought to 60°C for half an hour, agitating so that the chelate became soluble. A yellow solution was obtained which remained clear after return to ambient temperature. Its -2 -2 content was approximately 3x10 M of barium and 15x10 of aluminium.

Polymerization This co-catalyst composition was used in combination with normal butyl lithium to polymerize butadiene dissolved in heptane. The polymeriz15 ation conditions were the same as those described above (250 ml Steinie flasks, 123 g of heptane and 12.3 g of butadiene, 3 hours at 60°C).

The results obtained as set out in Table III below TABLE III Co-catalyst system Active initiator* n-BuLi (xlO 6moles) % conversion *9 trans-1,4 linkages W 1,2- linkages m f 20x105 moles Ba 12 55 2.0 77 2.9 (100xl0'b moles Al II (1 20 65 1.9 81 2.6 II II 28 70 1.9 82 3.0 ( 40x1o'6 moles Ba (200x10-b moles Al 40 63 1.2 86 2.0 (60x1 O'6 moles Ba (300xl0-b moles Al 28 47 1.2 78 2.6 II II 36 51 1.1 87 2.8 II II 59 61 1.1 90 2.4 II ii 75 65 1.1 90 2.7 II II 122 74 0.9 81 4.2 * See above In connection with Table IIA.

Example 4 Copolymerization of butadiene and styrene with the help of nbutyl lithium and the pre-formed co-catalyst system used in Example 3 An identical di benzoylmethane barium/triethyl aluminium co-catalyst composition to that used in Example 3 was employed.

Copolymerization was effected in 250 ml Steinie flasks as above, under the same experimental conditions.

Into each of these reaction flasks were introduced: - 123 g of heptane, - 12.3 g of monomers: 9.225 g of butadiene and 2.075 g of styrene (or 25? of the charge) - 65x10 moles of active n butyl lithium, and «6 - 60x10 moles of the co-catalyst complex reckoned as barium 15 (therefore accompanied by 300x10 6 moles of Al) At 80°C, the results obtained according to the duration of the reaction were as given in Table IV below.

TABLE IV Time ’/conversion achieved Overall ’/ by weight of styrene present in the copolymer Stereo configuration of the polydiene part trans-1,4 linkages (%) 1,2 linkages (%) 25 min 28 9 86 4 60 min 56 10 86 4 120 min 71 13 85 4 180 min 84 15 86 4 18 hours 94 21 86 4 The final copolymer obtained after 18 hours had an inherent viscosity of 1.1.

Example 5 Copolymerization of butadiene and styrene using n-butyl lithium/barium 5 nonyl-phenate/triethyl aluminium or diethyl zinc Preparation of the co-catalyst Barium nonylphenate was prepared by reacting nonylphenol (0.02 mole) and baryta (0.01 mole of Ba(0H)2) in the presence of 100 ml of toluene. The mixture was agitated whilst hot (60 to 80°C) until the baryta has completely disappeared. About one half of the solvent was evaporated under vacuum so as to entrain the whole of the water formed and the concentrated solution was made up to 100 ml by adding fresh toluene. In this way an approximately M/10 solution of anhydrous barium nonylphenate in toluene was obtained.

Copolymerization Butadiene and styrene were copolymerized in 250 ml Steinie flasks in the presence of: - heptane -butadiene - styrene - n-butyl lithium - barium nonylphenate 123 g, 9.225 g, 3.075 g, 50x10 3 moles (reckoned as active product),;nd -fi 50x10 0 moles. -fi To complete the catalyst system there were added either 100x10 -fi moles of triethyl aluminium or 100x10 moles of diethyl zinc.

For a comparison test, neither of these two compounds were added.

Copolymerization is effected at 70°C for varying time as set out in Table V which also lists the results obtained.

TABLE V Aluminium or zinc compound Time (min) conversion Overall ? by weight of styrene present in the copolymer trans linkages σ) 1,2 linkages w 45 60 45 13 52 11 [Al) = [Zn] = 0 90 120 58 16 53 10 180 45 60 46 9 71 5 [Al] = lOOpmoles 90 120 180 72 12 72 4 45 37 8 75 5 60 = lOOgmoles 90 59 8 75 4 120 180 72 13 77 4 41846 Copolymerization of butadiene/styrene and copolymers possessing two different sequences with their own stereo configuration.

This copolymer was obtained by adding during the polymerization one of the three constituents of the catalyst system, namely the triethyl aluminium, the normal butyl lithium and the barium compound being added together at the start of the reaction.

Into a 250 ml Steinie flask kept constantly under an atmosphere of rectified nitrogen there were introduced 123 g of heptane, 9.225 g of butadiene, 3.075 g of styrene, 50x10® moles of active n-butyl -fi lithium and 50x10 moles of barium nonyl phenate prepared as in Example 5. The mixture was allowed to copolymerize for one hour and thirty minutes at 70°C.

The percentage conversion reached 54% and the copolymer contained 16% styrene and had the following stereo configuration; 53% of trans15 1,4 linkages and 10% of 1,2 linkages (in its polybutadiene part). lOOxlO-6 moles of triethyl aluminium were then added to each Steinie flask and copolymerization allowed to continue at 70°C for one hour and thirty minutes. The final copolymer contained 14% of styrene. Furthermore, on an average 61% of the butadiene links were joined together as trans-1,4 linkages and 8% as 1,2 linkages. The overall conversion was 76%.

Thus the resultant copolymer possessed two sequences: -the first, representing 71% of the total copolymer contained on the one hand 16% of styrene and on the other hand 53% of trans-1, linkage and 10% of 1,2 linkage for the stereo configuration of the polybutadiene part, and -the second, representing 29% of the total copolymer contained on. the one hand 9% of styrene and on the other hand 79% of tRans-1,4 linkage and 4% of 1,2 linkages for the polybutadiene part.

Example 7 Polymerization of Butadiene by Means of n-Butyl Lithium and a Pre-formed Co-Catalyst System: Barium Hydride - Chlorinated or Unchlorinated Organo-Aluminium Compound Preparation of the co-catalyst systems Barium hydride and various organo-aluminium compounds were used to pre-form different co-catalyst systems under the following general conditions. g of barium hydride were placed in 250 ml Steinie flasks under an atmosphere of rectified nitrogen. 100 ml of heptane were added and then a quantity of aluminium alkyl or chloro-alkyl as given in the following Tables VII A and VIIB. The flasks were then placed in a thermostatically controlled tank at 60°C, where they were agitated for 6 hours. Any barium hydride which was not solubilized was then filtered off .'under an atmosphere of rectified nitrogen and the amount of barium in solution was determined.

A second series of co-catalyst system was produced using, in place of the heptane (100 ml per Steinie flask), toluene (20 ml per flask).

In Tables VIIA and VIIB below are listed for the heptane and 5 toluene series, respectively, the amounts of reactants used per Steinie flask, the final content of barium in the solution obtained after filtration, as well as the yield of barium per Steinie flask and the reference number give to the preparation.

Table VIΙΑ Organo-aluminium compound used Gram atoms of aluminium (xlO'3) Moles of HgBa (xlO-3) Final content of HgBa in moles/litre (xio-2) Yield % Reference 20.7 20.7 1.5 9.0 1 tri-ethyl aluminium 53.6 26.8 2.4 12.0 II 58.2 19.4 1.7 12.0 III 24.9 24.9 0.21 1.2 IV ethyl aluminium sesqui-chloride 53.2 26.6 4.2 24.0 V 78.3 26.1 6.4 43.0 VI 23.6 23.6 0.06 0.3 VII ethyl aluminium 46.4 23.2 0.1 0.6 VIII di chloride 90.3 30.1 0.1 0.5 IX 20.2 20.2 0.15 0.9 X diethyl aluminium 30.4 15.2 0.18 1.4 XI chloride — 43.2 14.4 0.6 5.8 XII TABLE VIIB Organoaluminium compound used Gram atoms of aluminium (xio“3) Moles of HzBa (xlO3) Final content of HgBa in moles/litre (χ io'2) Yield % Reference triethyl 21.0 21.0 7.3 11.5 XIII aluminium 15.8 XIV 43.4 21.7 7.2 58.2 19.4 5.2 25.1 XV 17.3 17.3 18.6 39 XVI ethyl aluminium 61 XVII sesqui- 41.8 20.9 21.3 chloride 56.1 18.7 22.7 89 XVIII 19.9 19.9 10 17 XIX ethyl aluminium 49.5 XX dichloride 25.8 17.9 19.4 51.6 17.2 21.7 70.5 XXI 21.0 21.0 1.3 2 XXII diethyl 2.8 XXIII aluminium 35.8 17.5 1.2 chloride XXIV 55.2 18.4 1.4 4.1 Polymerization With certain of the various co-catalyst systems 1 to XXIV butadiene was polymerized by introducing into 250 ml flasks 123 g of heptane, 12.3 g of butadiene, the co-catalyst system to give 50xl0-6 moles of barium eind active n-butyl lithium in the quantity stated in the Table VIIC below. The polymerization reaction was carried out with agitation for 24 hours at 70°C.

The results obtained, according to the quantities of n-butyl lithium used, are set out in Table VIIc below.

TABLE VIIC Organoaluminium compound used Co-catalyst system used Moles of active BuLi x IO6 % conversion V trans -1,4 linkages % 1,2 linkages % tri ethyl I 418 84 0.72 90 3.0 aluminium II 836 100 0.48 86 3.0 III 1,265 100 0.34 86 3.0 ethyl V 1,522 100 0.57 85 3.0 aluminium sesqui- chloride VI 1,458 100 0.57 84 4.0 triethyl XIII 340 100 0.71 88 2.4 aluminium XIV 654 100 0.50 89 2.8 XV 1,064 100 0.39 84 4.0 XVI 556 100 1.07 87 3.0 ethyl aluminium XVII 610 97 0.91 78 3.7 sesqui- chloride XVIII 740 83 0.74 86 2.7 ethyl XIX 540 92 1.15 70 5.0 aluminium chloride XX 497 100 1.14 71 5.0 Example 8 Polymerization of Butadiene by Means of n-Butyl Lithium/Barium Naphthenate/Diethyl Zinc Preparation of the catalyst Barium naphthenate, prepared from commercial naphthenic acid by neutralisation with sodium in an aqueous medium and precipitation with barium chloride, is a salt which is soluble in a toluene medium. Consequently, a solution of barium naphthenate in toluene containing 0.113 mole per litre of barium was used.

Polymerization Butadiene was polymerized under the same conditions as in Example 7 in 250 ml Steinie flasks, 12.3 g of butadiene to 123 g of heptane “6 “6 with 50x10 moles of barium naphthenate and 50x10 moles of active n-butyl lithium per flask, for 6 hours at 70°C.

The results, in relation to the quantities of diethyl zinc introduced, are set out in Table VIII.

TABLE VIII Moles of diethyl zinc x 10-6 % conversion trans-1,4- 1inkages (%) 1,2 linkages W 100 54 1.72 77 5 200 57 1.45 79 5 Example 9 Polymerization of Isoprene by Means of n-Butyl Lithium/Barium Nonylphenate/Triethyl Aluminium or Diethyl Zinc A solution of barium nonylphenate in toluene was prepared as in Example 5. Isoprene (12.3 g) was polymerized in 250 ml Steinie flasks in heptane(123 g) for 6 hours at 70°C with, per reaction flask: . -6 -50x10 moles of active n-butyl lithium, “fi -0 to 50x10 moles of barium nonylphenate, and 10 -0,100 or 200x10“® moles of triethyl aluminium or diethyl zinc.

In Table IX one can compare the affect of the combination of these various additives.

TABLE IX Moles Et,Al or Et2Zn x ^10-6 moles.Ba ' x IO’6 % conversion P trans-1,4 . linkages (%) 3,4 linkages (%) 0 0 100.0 1.54 18 8 0 50 84.5 1.19 14 10 100 Et3Al 0 100 1.15 22 6 100 EtgAl 50 ' 93.5 1.06 35 8 200 EtgAl 0 100.0 0.83 21 6 200 EtgAl 50 97.5 0.74 40 8 TOO Etz Zn 0 100.0 1.35 21 7 100 Et2Zn 50 96.5 1.05 25 7 200 EtgZn 0 100.0 1.21 23 6 200 EtgZn 50 93.5 0.87 25 7 Example 10 Copolymerization of Isoprene and Styrene using the same Catalyst System as in Example 9 Operating under the same polymerization conditions as in Example 7 in 250 5 ml Steinie flasks in a heptane medium (123 g) with 9.24 g of isoprene and 3.08 g or styrene (25% reckoned on the isoprene and styrene), copolymerization was continued for 2 hours at 70°C in the presence of SOxlO-6 moles of active n-butyl lithium. The copolymers resulting had the properties out in the following Table X.

TABLE X Moles of EtgAl or EtgAn x 10 Moles Ba x 10'® % conversion V % styrene Trans 1,4 linkages (%) 3,4 linkages (%) 0 50 57 0.96 18 13 12 100 EtgAl u 38 0.63 17 24 7 200 EtgAl 11 70 0.71 15 38 9 100 Et2Zn II 73 0.87 17 26 7 200 EtgZn II 73 0.80 17 25 8 Example 11 Copolymerization of Butadiene and Vinyl Toluene by Means of n-Butyl Lithium/ Barium Nonylphenate/Triethyl Aluminium In 250 ml flasks were copolymerized for 3 hours at 70°C: -9.24 g of butadiene, -3.08 g of vinyl toluene (commercial mixture of 2/3 metamethylstyrene and 1/3 of paramethylstyrene), -123 g of heptane, -50x10® moles of active n-butyl lithium, -50x10® moles of barium nonylphenate, and -200x10® moles of triethyl aluminium.

The results obtained were as follows: -conversion obtained: 64%, -n=0,97, -9% of vinyl toluene present in the copolymer, and -82% of trans-1,4 linkages and 3% of 1,2 linkages in the polybutadiene.

Example 12 Copolymerization of Butadiene and Tert-Butyl styrene using the 5 Same Catalyst System as that of Example 11 Into a 250 ml Steinie flask were introduced: -9.24 of butadiene, -3.08 g of tert-butyl styrene (95% of para and 5% of ortho), -123 g of heptane, -50xl0“6 moles of active n-butyl lithium, 50x10-6 moles of barium nonylphenate, and -fi -200x10 moles of triethyl aluminium.

The resulting polymerization was continued for 5 hours 30 minutes at 70°C. The results obtained were as follows: -7% of tert-butyl styrene present in the copolymer, and -85% of trans-1,4 linkages and 3% of 1,2 linkages.

Example 13 Mechanical Properties of Rubber Mixture based on Butadiene/Styrene Copolymer with a High Content of Trans 1,4 linkages and a Low Content of 1,2 linkages 1. Preparation of the copolymer The catalyst system described in Example 3, namely n-butyl lithium and a pre-formed co-catalyst system of dibenzoylmethane barium/ triethyl aluminium was used.

Polymerization was carried out in a 10 litre reactor under an atmosphere of rectified nitrogen with: -solvent: heptane;. 5040 g, /butadiene: 378 g, -monomers l J Ϊ (styrene: 126 g, -catalyst: active n-butyl lithium: 1.64x10 moles, /’barium: 1.64xl0-3 moles, -co-catalyst system / I aluminium: 8.2xl0_3mo1es, for 2 hours at 80°C.

The percentage conversion obtained was 75% and the viscosity reached was 1.4 dl/g at 25°C.

A 3-chain grafting ie attracting 3 chains of polymer to a single carbon atom, was then carried out by introducing into the medium whilst still active 1.64x10 moles of di phenyl carbonate, in accordance with our French Patent No. 2,053,786. Reaction was allowed to continue for a further 20 minutes at a temperature of 80°C. Methanol was added to stop the reaction and also an antioxidant (0.5 per cent by weight, reckoned on the rubber) and the elastomer (approximately 380 g) recovered by the steam distillation of the solvent and drying in vacuo.

The final viscosity after grafting had changed to 1.9 dl/g at 25°C. The Mooney viscosity (1+3 at 100°C) was then 45.

The resultant copolymer had the following stereo configuration: - 40 -75% of trans-1,4 linkages for the butadiene part - 5% of 1,2 The content of styrene incorporated was 8%. 2. Rubber Mix The elastomeric polymer described above was used for making a mix of the following formula: -elastomer 100 -stearic acid 2 -ZnO 3 -anti-oxidant (4010 NA) 1 -HAF black, Phil black 0 50 -Sundex 8125 processing oil (aromatic) 5 -Santocure 1 -Sulphur 1.6 The same mixture was prepared with a commercial butadiene/styrene copolymer (SBR 1500), by way of reference. On unvulcanised test pieces of these mixtures strength/elongation measurements (measurement of the green strength) were made and the results obtained are as follows: TABLE XIIIA Property SBR 1500, reference SBR of the test Elongation at break (%) 380.0 1,490 2 Breaking force (g/mm ) 20.0 92 2 Maximum force (g/mm ) 36.5 105 Thus the mixture obtained with the elastomer prepared in accordance with the invention had an improved mechanical behaviour as compared with the reference mixture.

The two mixtures were then vulcanised for 60 minutes at 144°C, The 5 mechanical properties obtained are set out in Table XIIIB.

TABLE XIIIB Property SBR 1500 reference SBR according to the invention 2 Modulus at 100% elongation (kg/cm ) 20.0. 22.5 2 Modulus at 300% elongation (kg/cm ) 95.0 110.0 Hysteresis loss at 60°C (%) 32.8 24.7 Shore hardness 68.0 70.0 Elongation at break (%) 665.0 500.0 Breaking force(kg/cm ) 250.0 225.0 It will be seen that the elastomer prepared in accordance with the invention, that is to say SBR with a high content of trans-1,4 linkages and a low content of 1,2 linkages had the properties of a rubber and even of a good rubber if one considers the level of hysteresis losses achieved.

The word Santocure is a registered Trade Mark.

Claims (1)

1. CLAIMS 1. A catalyst composition suitable for use in the homopolymerization or copolymerization of olefins consisting essentially of a lithium initiator (as herein defined), and a co-catalyst containing a 2. A catalyst composition as claimed in Claim 1, in which the lithium initiator is an alkyl aliphatic organo-lithium compound, an alkenyl organo-lithium compound a living polymer of poly10 butadlenyl lithium, polyisoprenyl lithium, or polystyryl lithium or an aromatic organo-lithium compound. 3. A catalyst composition as claimed in Claim 1 in which the lithium initiator is a polymethylene dilithium compound, a compound resulting from the reaction of metallic lithium with an aryl-substituted IE ethylenic compound or lithium anthracene, lithium naphthalene, lithium chrysene or lithium diphenyl. 4. A catalyst composition as claimed in any of Claims 1 to 3 in which the barium or strontium compound is BaH 2 or Sr H 2> a salt of a mono or dibasic carboxylic acid or the corresponding monofunctional or difunc» tional thioacid, a monofunctional or polyfunctional alcoholate or thiolate, or a monofunctional phenate or thiophenate, a β-diketonate of barium or strontium, diphenyl barium or strontium, biscyclopentadienyl barium or strontium, trialkyl silyl or triphenyl silyl barium or strontium, a barium or strontium salt of a secondary amine, a barium 15 or strontium ketyl, or barium or strontium naphthalene, anthracene or chrysene. 5. Composition is added in such a manner as to regulate the content of trans-1,4 linkages in the resulting polymer at from 45 to 95%, and the content of 1,2-linkages at from 3 to 12%. 5 the constituents are dissolved or in suspension in a hydrocarbon solvent 5 aluminium hydride. 5. A catalyst composition as claimed in any preceding claim in which the organo-metallic compound of Group IIB or IIIA is a zinc or cadmium dialkyl, a halogenated or non-halogenated organoaluminium compound, an organo boron compound, or a dialkyl 5 compound of barium or strontium and an organo-metallic compound of a metal of Group IIB or IIIA of the Periodic Table. 6. A catalyst composition as claimed in any preceding claim in which the constituents are present in quantities such that the ratios fall within the following limits: moles R 3 Me IIIA or R 2 Me IIB 0.2<- $ 10 moles of compound of Ba or Sr moles of compound of Ba or Sr 10 0,25$ $ 5 gram atoms of Li in which R Me IIIA represents the organo-metallic compound of a metal 2 of Group IIIA and R Me IIB represents the organo-metallic compound of a metal of Group IIB. 7. A catalyst composition as claimed in Claim 6 in which the 15 constituents are present in quantities such that the ratios fall within the following limits: moles R 3 Me IIIA or R 2 Me IIB 0.5 < - <6 moles of compound of Ba or Sr and moles of compound of Ba or Sr 0.5 _ ^1.5 gram atoms of Li 8. A catalyst composition as claimed in any preceding claim in which 9. A catalyst composition as claimed in any preceding claim in which the lithium initiator is n-butyl lithium and the cocatalyst comprises barium phenate and a trialkyl aluminium. 10. Catalyst composition is added in such a manner as to regulate the content of trans-1,4 linkages in the resulting polymer at from 10 to 45% and the content of 3,4-1inkages at from 5 to 10%. 10 polymerization reaction which has previously been initiated by the addition of the lithium compound. 10. A catalyst composition as claimed in claim 1 suitable for use in lo the homopolymerization of copolymerization of olefins substantially as herein described in any Example. 11. A process for the homopolymerization of conjugated dienes or the copolymerization of conjugated dienes with one another or with one or more aromatic vinyl compounds in which the monomers are reacted 15 in the presence of a catalyst composition consisting of an organolithium initiator and of a composite co-catalyst containing a compound of barium or strontium and an organo-metallic compound of a - 46 metal of Group IIB or IIIA of the Periodic Table. 12. A process as claimed in Claim 11 in which the catalyst composition is as cl aimed in any of claims 3 to 10. 13. A process as claimed in claim 11 or claim 12 in which the 5 co-catalyst has been pre-formed and then added at the same time as the lithium initiator at the commencement of the polymerization reaction. 14. A process as claimed in Claim 11 or Claim 12 in which the preformed co-catalyst is added in one or more portions during the 15. Styrene. 20. A process as claimed in claim 11 for the homopolymerization of conjugated dienes or the copolymerization of conjugated dienes with one another or with one or more aromatic vinyl compounds substantially as herein described with reference to any of the Examples. 15 in one or more portions simultaneously with the lithium initiator, b) one after the other in either order during the polymerization reaction which has been previously initiated by the lithium initiator, or c) jointly in one or more portions during the polymerization 20 reaction which has been initiated previously by the lithium initiator. - 47 15. A process as claimed in claim 11 or claim 12 in which the components of the co-catalyst system are added:a) . separately at the commencement of the polymerization reaction 16. A process as claimed in any of claims 11 to 15 in which the conjugated diene is butadiene. 17. A process as claimed in any of claims 11 to 16 for the preparation of a butadiene homopolymer or copolymer in which the catalyst 18. A process as claimed in any of claims 11 to 15 for the preparation of an isoprene homopolymer or copolymer in which the 19. A process as claimed in any of claims 11 to 18 for the preparation of a copolymer in which the aromatic vinyl compound is 20 21. A homopolymer or copolymer when prepared by a process as claimed in any of claims 11 to 20.