IE42880B1 - Anionic polymerization of conjugated dienes - Google Patents

Abstract

1531085 Catalyst system in anionic diene polymerization MICHELIN & CIE (COMPAGNIE GENERALE DES ETABS MICHELIN) 26 Feb 1976 [27 Feb 1975] 07677/76 Heading C3P Conjugated dienes are homopolymerized or copolymerized with one another and/or with a vinyl aromatic compound at 50‹ to 120‹ C. in the presence of a catalyst formed from (A) an organometallic compound of a Group IIIB element (boron, aluminium group) having the formula where Me1 is an alkali metal atom, Me2 is an alkaline earth metal atom, M is a metal of Group IIIB, R1 to R3 are alkyl or aralkyl, R4 is alkyl, aralkyl, or XB where X is O, S, NB, where B is alkyl, aralkyl, or M(R5R6) in which R5 and R6 are alkyl or aralkyl, and (B) an electron-donor compound. The monomers are typically butadiene or butadiene/styrene, while exemplified catalyst components include (A) Ba[AlEt 4 ] 2 , Ba[AlEt 3 OR] 2 , where R is nonyl phenyl, Li(AlEt 4 ], Li[AlEt 3 OiPr], LiOAlEt 2 , Li[AlEt 3 OAlEt 2 ], AlEt 3 , and Li[BEt 3 Bu], and (B) tetrahydrofuran, methanol, water, lithium isopropylate, tetramethylethylene diamine, picoline, acetonitrile, acetone, diisobutyl sulphide, hexamethylphosphoramide, lithium isopropylate/barium nonylphenate mixture, potassium t-amylate, the lithium salt of diethylene glycol monoethyl ether and the lithium salt of diethylaminoethanol.

Description

This invention relates to the production of homopolymers of conjugated dienes or copolymers of conjugated dienes, with other conjugated dienes and/or with an aromatic vinyl compound.

Such homopolymers or copolymers of conjugated dienes can be prepared as described in British Patent No. 1,246,914 by polymerization in solution in the presence of organo-metallic compounds of an alkaline earth metal of the formula: mWtW*, in which 2 M represents calcium, barium or strontium, M represents zinc or cadmium and R ,R^SR^3, and R^ each represent a hydrocarbon radical. However, the polymers obtained have a very low intrinsic viscosity which is between 0.24 and 0.62.

These homopolymers or copolymers can also be obtained as described in chemical abstracts, Vol.78; 85 514 (1973) and RAPRA No. 23 238 L (1974) by polymerization in solution in a hydrocarbon medium with the aid of an organometallic compound of an alkaline earth metal and aluminium. However, the polymers obtained by this process, just like the polymers mentioned above, have a very low viscosity and on this account do not have the sufficient elastomeric properties for use as the principal component in mixtures serving for the manufacture of pneumatic tyres. In addition, such a method of manufacture cannot be used industrially because of the very low polymerization rate speed.

Organic compounds of aluminium have an extremely low or even zero intrinsic catalytic activity and they are not considered as initiators for the homopolymerization or copolymerization of conjugated dienes.

We have now found a process by which it is possible to obtain industrially,·in relatively short times and with a good yield, homopolymers or copolymers of conjugated dienes and/or aromatic vinyl compounds which have an elasticity similar to that of rubber and which can be used in the manufacture of pneumatic tyres.

Therefore, according to the present invention there is provided a process of homopolymerization of a conjugated diene or of copolymerization of conjugated dienes with one another and/or with an aromatic vinyl compound, at a temperature of from 50° to 120°C in the presence of a catalyst system which consists only of the reaction product of (a) an organic compound of a metal of Group ΠΙΑ of the Periodic Table of Elements according to the Mendeleev classification, conforming to one of the following formulae: He1 M R1 R2 R3 R4 Me2 [M R1 R2 R3 R4] M R1 R2 R3 Me1 OMR1 R2 i 2 in which Me represents an alkali metal atom. Me represents an alkaline earth metal atom, M represents a metal of the Group IIIA of the Periodic Table of Elements according to the Mendeleev 12 3 classification, R , R , and R each represents an alkyl or aralkyl radical and R4 represents an alkyl radical, an aralkyl radical, or the radical XB in which X represents oxygen, sulphur^or NB where N is a nitrogen atom and B represents δη 5 6 alkyl radical, an aralkyl radical, or the radical M(R R ), in 5 5 which R and R each represents an alkyl or aralkyl radical, with (b) one or more electron donor compounds which contain one or more of the atoms, oxygen, sulphur, nitrogen and phosphorus which compounds are aprotic polar compounds, protic polar compounds, or compounds which are the reaction product of a protic polar compound with an alkali or alkaline earth metal, the catalyst system being the reaction product of component (a) with component (b) only and either being preformed by the reaction of components (a) and (b) at a temperature in the range 20 to 100°C or being formed in situ by the addition of components (a) and (b) to the monomer reaction mixture.

Thus we have surprisingly found that the reaction product of compounds which,taken individually, are not initiators for the homopolymerization or copolymerization of conjugated dienes or which have only an extremely low intrinsic initiating activity, forms a catalyst system capable of industrial use for initiating the homopolymerization and the copolymerization of conjugated dienes either alone or with aromatic vinyl compounds.

References to the Periodic Table of Elements according to the Mendeleev classification refer to that table on page B3 of Handbook of Chemistry and Physics 47th Edition, Robert C. Weast, published by The Chemical Company.

The organic compounds of a metal of the Group III A which are particularly suitable as a constituent of the catalyst system are those in which the alkali metal is lithium, sodium or potassium and those in which the alkaline earth metal is magnesium, calcium, strontium or barium. Examples are A1(CH3)3, A1(C2H5)3, Al(i-C4Hg)3, Li[Al(C2H5)4j , .

Na £ A1(C2H5)4·] , K^Al(C2Hg)^, Li [A1(C2H5)3OC2H53 , LiW2H5)30Al(C2H5)2] ,Mg[Al(C2H5)J 2, Ca[Al(C2H5)4]2, Sr[Al 2> Ba[Al(C2H5)4]2j BarA1(C2H5)30C2H5]2> Ba(Al-(1so C4H9)^J2j LiOAl(C2H5)2> NaOAl(C2Hg)2i B(CH3)3> B(C2Hg)3( LiB(C2Hg)4> LiB(C2H.)3C4Hg, Ga(C2Hg)3# In (C2H5)3 and Tl(C2Hg)3t - 6 Especially suitable aprotic polar compounds are ethers and particularly cyclic ethers, such as tetrahydrofuran and dioxane, as well as the corresponding thioethers, tertiary amines such as Ν,Ν,Ν',Ν1 - tetramethyl - ethylene-diamine, aromatic amines and especially derivatives of pyridine and the corresponding oxides, phosphorised compounds such as the phosphines and their oxides, phosphites, phosphoramides and especially hexamethylphosphorotriamide, ketones and particularly acetone, nitriles and particularly acetonitrile, aldehydes, esters, amides, nitro-aliphatic or aromatic compounds, sulphoxides and especially dimethyl sulphoxide , sulphones and sulphites.

Especially suitable protic polar compounds are water, alcohols and particularly methanol, primary or secondary amines and thiols.

Particularly suitable as compounds of the products of reaction of a protic compound with an alkali or alkaline earth metal are the alcoholates and the phenates of alkali or alkaline earth metals, the alkali or alkaline earth mercaptophenates and thiophenates and also the ether-alcoholate and amine-alcohol ate compounds.

The organic compound of a metal of the Group III A and the polar compound or compounds can be introduced into the reaction medium, either separately in any desired order or in a preformed - 7 condition. According to the second variant the catalyst system is preformed by mixing the various constituents and then bringing the mixture to a temperature which is between 20 and 100°C for 5 to 60 minutes.

The two constituents of the catalyst system can be used in variable proportions, but it is preferable to use them in proportions such that the molar ratio between the polar compound or compounds and the organic compound of the metal of Group III A is from 0.01 to 100. For a given concentration of organic compound of the metal 10 of Group III A, a modification of the value of the molar ratio may at the same time modify the viscosity and the microstructure of the polymer formed, as well as the speed of the reaction.

Among the organic compounds of a metal of Group III A, it is the organo-aluminium compounds which are preferentially used, either because of their advantageous method of manufacture or because they are widely available industrially.

In the case of catalyst systems which are formed by an organic compound of aluminium conforming to the formula Me2[Al R1 R2 R3 R4]2, 2o as previously defined, and one or more aprotic polar compounds, for a given concentration of organic aluminium compounds, when the value of the molar ratio between the aprotic polar compound or compounds and the organo-aluminium compound increases, the speed of reaction and the viscosity of the polymer formed increase without the microstructure of the polymer being modified. This is all the more surprising, since the addition of polar compounds to organolithium initiators leads to a system not modifying the viscosity of the polymer but modifying the microstructure thereof.

In the case of catalyst systems which are formed by an organic compound of aluminium corresponding to- the formula Me2 (M R1 R2 R3 R4) 2, such as previously defined, and a polar compound selected from those which correspond to one of the following formulae: R(0CH2CH2)n 0 MeJ (R2) NCH2CH20 Me1, in which Me^ represents an alkali metal, R represents an alkyl radical and n is an integer, it is possible to obtain homopolymers and copolymers which have a very high content of 1, 4-trans chains (up to 92%) and a very small content of 1,2or 3,4-chains, that is to say, below 4%, so preserving an elastomeric character. The butadiene and styrene copolymers thus obtained have a resistance to elongation similar to that of natural rubber when they are in the crude (unvulcanised) state and when they are loaded in accordance with the usual formulations employed when manufacturing pneumatic tyres.

The homopolymerization or copolymerization reaction can be effected in an inert solvent, which may for example be an aliphatic or alicyclic hydrocarbon such as pentane, hexane, heptane, iso-octane, cyclohexane or an aromatic hydrocarbon such as benzene, toluene or xylene, or in bulk.

The reaction is carried out at a temperature which is from 50 to 120°C, preferably from 80 to 100°C, and is preferably conducted under a pressure which corresponds to the vapour pressure of the reactants. The process of the invention may be operated intermittently or continuously.

The process of the invention not only allows one to achieve high yields of macro-molecular compounds per unit of weight of the catalyst system, but also allows the molecular weight of the prepared homopolymers and copolymers to be regulated within the desired range.

The process also allows one to obtain homopolymers and copolymers which may, during reaction, result in grafting reactions with all the reactants capable of reacting with living polymers. -10Examples of conjugated dienes suitable for homopolymerization or copolymerization according to the invention are buta - 1,3 diene, isoprene, 2,3 - dimethyl - buta - 1,3 - diene, penta 1,3 - diene and 2-ethyl butadiene.

Examples of aromatic vinyl compounds which may be copolymerized with the conjugated dienes are styrene, ortho-,meta-, and para-methyl styrene, di-and poly-methyl styrenes, paraand tert-butyl styrenes, vinyl naphthalenes, methoxystyrenes, halostyrenes ahd divinyl benzene.

The polymers obtained by the method of preparation making use of the catalyst system according to the invention have a microstructure which may be extremely variable, in addition to a wide distribution of the molecular weight and a high intrinsic viscosity, that is to say, sufficient for the products to be used as the principal constituent of mixtures Serving for the manufacture of pneumatic tyres. In effect, the content of 1,4trans chains can be between 20 and 90?! and the content of 1,2 chains can be between 1 and 60%. Furthermore, these products have a very good suitability for mechanical working on tools.

The invention will be illustrated by the following Examples, some' of which describe by way of illustration particular methods as regards procedure. In all the Examples, the inherent viscosities were established at 25°C in a solution of 1 g/litre in toluene, the concentrations of catalysts are expressed in micro-molecules - 11 per 100 g of monomers and the homopolymerization or copolymerization reactions were stopped, when the conversions reached 80£?except in the case of Examples 19,23 and 27?.by adding methanol in suitable quantities (12! by weight of monomers in the reaction). The percentages of 1,4-trans and of 1,2 are expressed in relation to the polybutadiene part, while the percentage of styrene is expressed in relation to the total quantity of polymer obtained.

Example I Into a reactor under rectified nitrogen pressure were introduced 2 litres of heptane as solvent, then 205 g of butadiene and 69 g of styrene, and the temperature was raised to 80°C,The catalyst system, formed by reacting Ba[Al (CgHg)^ and tetrahydrofuran (THF) was added in succession in variable quantities. When the desired degree of conversion was reached, the reaction was stopped and the copolymer recovered.

The results are set out in the following Table I. 880 Copolymers steric configurations % styrene incorp. in tn io io !— r— r“ t— CM CO CO CO 4-> &S i-? in r— © o co co 00 co inherent viscosities m CO 10 γ- Ο 1— CM CM Reaction time o PO X fi fi fi o ra· co co ra- Catalyst system THF ooo o o o o i— cm ra* p— cm ra* CM in X CM O r— ώ m CQ ο o o o CM Ο Ο Ο CO Γ— r— r— Test Control 1 2 3 - 13 It can be seen that reaction times are 5 to 10 times shorter using a catalyst as required according to the invention and that, as the value of the ratio of THF/Ba [A1(C2H5)J 2 increases, the speed of reaction and the viscosity of the copolymer increase, while the microstructure of the copolymer remains substantially unchanged.

Example 2 Four tests were carried out, repeating the working procedure of Example 1, with different catalyst systems. The results are set out in the following Table II. 22880 TABLE II polymers steric configurations 1 ; % styrene incorp. o oj io io r·» π·· r- i—» oj fc? Γ-* Γ» *d* to S- fc? * to oo o «3· Ν» h- 00 K Ο ο inherent j viscosities m TO *3· OJ o r- r— OJ Γ- Reaction time O © OJ TO jz jz sz TO 04 «3* OJ Catalyst system THF oooo OJ o o co cn in to in i— TO TO Ol amount o o o o cj- Ο O LO LO r— f— CO i— f— OJ 1^31 in X ou cj ou Φ ε OJ oj' *d·’ OJ OJ t—5 i—» r—1 in rt *4* «4* X S—» <—» z-> OJ in in in u XX X o oj oj oj ω ο ο ο ·ι- s ,< < < u—» 1—1 t_1 ίβ S- fO fO CJ (/) CQ CQ Test i— 0J TO 4· 428S0 - 15 Example 3 Three tests were performed. Into a 250 ml Steinie flask under rectified nitrogen pressure were introduced 100 ml of heptane, as solvent and 13.6 g of butadiene. The catalyst 5 system, formed by BajAl(C2Hg)4] 2 and methanol, was then added. The flask was placed in a tank thermostatically controlled at 80°C, in which it was agitated.

On completion of the reaction, the poly-butadiene was recovered by a conventional procedure. The results are set out in the following Table III. 0 Φ c φ •Γ” •Ό (0 Ρ 3 >) Γ- Ο α. steric configurations CJ co co co (Λ C fO S X- LD «qf- ιΟΟ CO CO inherent viscosities «3- cn © LD LO LO Reaction ι time Λ .E -C t·-. lo tn Catalyst system i methanol •5f CM ST IS Cd 'ί CM CM r_S- in X CJ o r— L<. (0 CQ OOO OOO r— r— r- Test r- CM CO - 17 Example 4.

The operating procedure of Example 3 was repeated except that a catalyst system which was formed by Ba [Xl(CgHg)^]2 and water was used. The results are set out in the following Table IV. ω c ω »r* -ο (0 Ρ 3 .Ω >> r— Ο ο_ steric configurations CM CM CA C <0 $- P r— hs 00 inherent viscosities Ln in i Reaction time -c h*. r— o CM X O «0* Catalyst system CM Γ“» rn X CM O CO CQ 0011 4288ο - 19 Example 5 Three tests were carried out, the reaction taking place in a reactor under rectified nitrogen pressure. 2 litres of heptane were introduced as solvent, followed by 191 g of butadiene and 82 g of styrene. The temperature was raised to 80°C and the catalyst system, formed by Sa[Al(CgHg)^]2 and lithium iso-propylate was added. On completion of the reaction, the copolymer was recovered by a conventional procedure. The results are set out in the following Table V. - 21 Example 6 Two tests were performed. Into a reactor under rectified nitrogen pressure were introduced 2 litres of solvent (heptane) and then 205 g of butadiene and 69 g of styrene. The temperature was brought up to 80°C and then there were successively added the components of the catalyst system, Ν,Ν,Ν',Ν1 - tetramethyl - ethylene diamine (TMED) and Ba[Al(C2Hg)J2. The results are set out in the following Table VI. so - 22 ο Q. Ο Ο Ρ ε CD <Γ C Ο αι Ρ φ C α. φ s- S- ο ΙΛ ID >» υ r™ r— Ρ C (Λ ·Γ“ ss V5 OJ «4* *4* *— S- Ρ «4* *4* Γ“ CO CO SS ΙΛ Ο »— ρ σι S? Ρ (Λ >» Ρ ¢0 ο C ο »ι- Φ ρ ε ο «ίΠ3 Ρ ω 0£ «Μ ιη ο *4* «4· CVl ο <4* CSJ ο <4· «4- 23 42880 Example 7 Into a reactor under rectified nitrogen pressure were introduced 2 litres of heptane, 205 g of butadiene and 69 g. of styrene, whereafter the temperature was raised to 80°C and the following were added in succession: methyl - 4 - pyridine (γ-picoline) and BajAl(C2Hg)4]2 · ^he results are set out in the following Table VII. 380 - 24 TABLE VII - 25 42880 Example 8 Two tests were carried out, repeating the operating procedure of Example 3, but using the following catalyst system: Ba[Al (C2H5) 412 and acetonitrile. The results are set out in the following Table VIII. 02880 Polybutadiene steric configuration CM co ra (/) E ra ra P i— i·*·. inherent viscosities co r-» r— r— Reaction time LO ΙΛ ra r— -E fi co co Catalyst system acetonitrile ra cm r-·» cm CM CM Lf) X CM O ns cQ o o σ o Test r~ CM Example 9.

Three tests were carried out, repeating the operating procedure of Example 3 and using similar conditions, except that acetone and Ba[Al(C2Hg)4]2 were used as the catalyst system. The results are set out in the following Table IX.

CQ CO CT o 0) o o •r~ ε CO co +J r“ () -P -C _c JZ <0 <11 fv. co in oc CQ I— - 29 Example 10.

The operating procedure of Example 3 was repeated using similar conditions, except that thiodiisobutyl and Ba[Al(CgHg) were used as the catalyst system. The results are set out in the following Table X. >80 X Ul _J CQ < - 31 Example Π Three tests were performed repeating the operating procedure of Example 3 and using similar conditions, except that hexamethyl phosphorotriamide (HMPT) and Ba[a1 (CgHgj^g were use^ as the catalyst system. The results are set out in the following Table XI.

Polybutadiene steric configurations Ol fc? Ol TO co ω c «j «4· μ « •P r— fc? οί o co co co r> inherent viscosities to co co in to «4· r— i— 04 Reaction time LO Z £ JZ TO Oi OJ Catalyst system | HMPT οι co Ol *4» CO OJ «4· CO Ol tn X Ol o (0 CQ OOO ooo i— r·* r f*— r~ t~— Test r— 04 TO - 33 Example 12 Two tests were carried out repeating the operating procedure of Example 3 and using similar conditions, except that Ba[Al (C,Hc) Or] OR being a nonyl phenate radical, and lithium 5 3 2 isopropylate were used as the catalyst system. The results are set out in the following Table XII.

L388 0 Polybutadiene steric configurations CM r* 4- O ra ra 1/) E (0 s- ra a to co pR. P>. inherent viscosities 1.15 1.33 Reaction time fi fi co ρ-» Catalyst system lithium isopropylate 2900 5800 CM r—“i cd o co tn CM O tS re co o © .lo in «3· ra Test i— CM - 35 Under the same conditions, it was found that the use of Ba [Al(CgHgJgORjg by itself did not lead to any trace of polymer, even after 48 hours.

Example 13 Two tests were carried out, repeating the operating procedure of Example 3 and using similar conditions, except that Li^l(CgHg)^ and lithium isopropylate were used as the catalyst system. The results are set out in the following Table XIII.

TABLE XIII Polybutadiene steric configurations CM P O 00 00 ω c s- P « o o tn to inherent viscosities CM <3* CM CM r—- p— Reaction time 3 h 30 3 h 30 Catalyst system lithium isopropylate 725 1450 rgi ty** in X CM O l£Li P σ o in in <5f Test t— CM Under the same conditions, the use of either (CgHg)^J by itself, or of lithium isopropylate by itself, did not lead to any trace of polymer, even after a reaction time of 48 hours.

Example 14 A test was carried out, repeating the operating procedure of Example 3 and using Li^Al(CgHg)^, lithium isopropylate and barium nonyl phenate as components of the catalyst system. The results are set out in the following Table XIV.

TABLE Polybutadiene steric figurations J 04 M- O d* uoo ΙΛ c <3· <0 « £4 e•P fc* σ» fx inherent viscosities 2.3 Reaction time o co -C r— Catalyst system I--- I lithium isopropylate 2900 barium nonyl phenate 725 =c OJ o o m - 39 As compared with the preceding Example, the addition of the barium nonyl phenate has the effect of orienting the microstructure.

Example 15.

The operating procedure of Example 3 was repeated except that the catalyst system Li^l (CgHgj^and sodium tert.-amylate was used. The results are set out in the following Table XV. 380 s, Φ p «Ρ (O i3 <4 Ρ JQ 5S σι Φ •Ρ ·ι— C «Ρ φ >r~ i. (Λ Φ O -c u s σι •° & <0 -P Φ az JZ «4* Φ •p (0 i. φ •P - 41 Example 16 Two tests were carried out, repeating the operating procedure of Example 3, except that a catalyst system which was formed by Nc^l(C2Hgand potassium tert.-amylate (ROK) was used. The results are set out in the following Table XVI. - 42 TABLE XVI GJ C 1 Ο 0. steric configurations CM «— 4- O CO U3 CO CO w c re S- +5 ra i— pR. O co ra inherent viscosities 3.12 2.55 Reaction time j 5 h 5 h Catalyst system bd O Cd 725 1450 ηη m X CM O ΐ 3» 1450 1450 1- Test ι— CM 4288C - 43 Under the same conditions, the use of NejKl(c2H5)]jJby itself did not lead to any trace of polymer, even after 48 hours.

Example 17 A test was carried out, repeating the operating procedure of Example 3, except that a catalyst system formed by ^(^Hg)^ and potassium tert.-amylate (ROK) was used. The results are set out in the following Table XVII. 580 diene ons CM 4— O 26 steric configurati ω c •P r- 50 ro P 3 JD >) O Cu inherent viscosities 1 1.37 Reaction time © CO JZ «ςί- Catalyst system 5Z o OC 1 360 c? LO ΠΣ CM O © LO r— - 45 42880 Under the same conditions, the use of l£l(C2H5)4Jby itself did not lead to any trace of polymer, even after hours.

Example 18.

A test was carried out, repeating the operating procedure of Example 3 and using the catalyst system. and barium nonyl phenate. The results are set out in the following Table XVIII. (8 8 0 TABLE XVIII Φ c φ ό (Ο Ρ Λ >> SΦ +> W CM Ο- Ο < • rans f^· O Ρ co ι— Ρ C φ Sφ J= o ·<- Φ P ε o •r— <0 P Φ Q£ .Ε ο <ΰ ρ <β ο Er- Ρ □ >) 0 •γ- C C £- Ο Φ co χ ο co χ ο CM ιη χ CM V5-J - 47 42880 Under the conditions, the use of by itself did not lead to any trace of polymer, even after 48 hours.

Example 19 A test was carried out, repeating the operating procedure of Example 3 and using the catalyst system LiOAl(C2Hg)2_and barium nonyl phenate. The polymerization reaction was stopped when the conversion reached 60%. The results are set out in the following Table XIX. 5880 - 48 TABLE ω c Φ «ι- Ό nJ Ρ 3 JO >> Γ*· ο ο. ω C ο •Γ Ρ Ο: ίθ •ι- Si. =3 Φ στ Ρ <ι<Ό 4C ο ο CM Γ“ Μ- Ο LO ΙΛ C <4 £· *4* Ρ * ^5 63 inherent viscosities cn r“ ί Reaction time J= LO Catalyst system barium nonyl phenate © «4* Ρ-» CM Lf) 3Z CM O r“ g •r“ —J 2960 - 49 42880 Under the same conditions, the use of LiOAl(CgHgJg by itself did not lead to any trace of polymer, even after a reaction time of 48 hours.

Example 20 Two tests were carried out, repeating the operating procedure of Example 3, but using the following catalyst system. lt[ai(c2h5)3o ai(c2h5)2] and lithium isopropylate. The results are set out in the following Table XX. 880 - 50 TABLE Polybutadiene steric configurations 4— O CM RQ ffi ffi (Λ C Π3 s- ra +3 « (5¾ CO ffi tn tn inherent viscosities co in pR. ffi r™ Reaction time 5 h 30 5 h 30 Catalyst system lithium isopropylate £ S CO r— r- tn X CM O P“ O CO ZPR in X CSJ U r“ lS •r· O O ο σ ρ— i— r— r~ Test i— CM Under the same conditions, the use of Li [ai (C2Hg)30 Al(C^Hg)23 by itself did not lead to any traces of polymer, even after 48 hours.

Example 21 Two tests were carried out, repeating the operating procedure of Example 3 but using the catalyst system Al(C2Hg)3, lithium isopropylate and barium nonyl phenate. The results are set out in the following Table XXI. 380 TABLE Polybutadiene steric configurations % of 1.2 TO TO (Λ C G3 *4 S- •P r- fc? co in co co inherent viscosities 1.7 1.35 Reaction time 5 h 5 h 1 Catalyst system harium nonyl phenate 360 720 lithium isopropyl ate 3600 1 3600 TO LO X CM O 2900 2900 Test 1— CM 4288C - 53 Under the same conditions, the use of Al(C2Hg)3 by itself did not lead to any trace of polymer, even after 48 hours.

Example 22.

A test was carried out,repeating the operating procedure of 5 Example 3 except that LiB(C2H5)3 C^Hg and barium nonyl phenate were used as the catalyst system. The results are set out in the following Table XXII.

SO - 54 TABLE XXII utadiene ic ations t % of 1.2 c*5 ster configur 1Λ C re S- «3* p « 1“ cc co fi >) o . a. inherent viscosities co a r— Reacti on time fi Catalyst system barium nonyl phenate 0011 Sn ty** in XCM CJ S’ •r* P 5900 - 55 42880 Under the same conditions, the use of LiB(C2Hg)3C4Hg by itself did not lead to any trace of polymer, even after 48 hours.

Example 23.

Into a reactor was continuously introduced a mixture of heptane, butadiene and styrene, having a ratio by weight of monomers to solvent of 1:5 and of butadiene to styrene of 3. BafAl(CgHg)^g and lithium isopropylate were also introduced continuously in a molar ratio of 1:10 at such a rate of flow that there were in the reactor 960 μ moles of Ba [Al(C2Hg)4]2 per 100 g of monomers and an average residence time in the reactor of IJ hours. The copolymerization was effected at 90°C and the conversion achieved was 60%. The copolymer was recovered at the outlet of the reactor. This copolymer contained 16% of styrene and had an inherent viscosity of 1.64, a content of 1,4-trans chains of 81% and of 1,2 chains of 3%.

Example 24 Into a reactor under rectified nitrogen pressure were introduced 2 litres of heptane, 191 g of butadiene and 82 g of styrene and the temperature was raised to 80°C. A catalyst system was then added in succession, that system being formed by 460 μ moles - 56 12880 of Ba[Al(C2Hg)4]2 per 100 g of monomers and 1380 μ moles of lithium isopropylate per 100 g of monomers. When the conversion had reached 80% (2 hours), 50 cc of copolymer were recovered and in that portion the polymerization was stopped by adding methanol. A quantity of diphenyl carbonate (CDP) such that the ratio CDP_ Ba[Al(C2H5)4]2 was equal to 0.5 was then introduced into the reactor.

The copolymer obtained was recovered by a conventional process.

The microstructure of the copolymer obtained, before grafting, and of the grafted copolymer, was as follows: 81% of 1,4trans chains, 4% of 1,2 chains and 24% of incorporated styrene.

The viscosity of the non-grafted copolymer was 1.7 and that of the grafted copolymer was 2.6.

Example 25. 1. Preparation of the copolymer: Into a reactor under rectified nitrogen pressure were introduced 2 litres of heptane, 191 g of buta - 57 43880 diene and 82 g of styrene and then the temperature was raised to 80°C. A catalyst system formed by BaCftl(CgHg)^],, and lithium isopropylate was then added in succession. When the conversion was 80%, the reaction was stopped and the copolymer recovered in a conventional way. The elastomer as obtained was then diluted with 37.5 parts of aromatic oil (Exarol MX 140, marketed by Compagnie Francaise de Raffinage) per 100 parts of dry elastomer. The results are set out in the following Table XXV A.

Stearic configuration I % styrene incorp. CM CM fc? CM Ct w I c *t fO * sfc? r- -P «4· co i nherent viscosity before | after dilution with the oil 1 2.67 1.96 Reaction time ( 5 h 30 Catalyst system o o r— Γ*» CM r^.· LO X CM ω «μ* («Β uS ra co OOOL - 59 2. Rubber industry mixture: The elastomer as described above was used for preparing a mixture which corresponds to the following formula: Elastomer diluted with 37.5 parts of aromatic oil 100 Stearic acid 2 ZnO 3 AntioxidarifcfSantoflex 13: N(dimethyl)1,3-butyl)N'10 phenyl-p-phenylene diamine] 1 HAF carbon black (Philblack 0) 50 Aromatic oil (Sundex 8125, mole weight 380, density 0.995) marketed by Sun Oil 5 Santocure (n-cyclohexyl-mercaptobenxthiazole sulphenamide) 1 Sulphur ' 1.8 The same mixture was prepared with a commercial butadienestyrene copolymer (SBR 1712), to serve as a control. The two mixtures are then vulcanised for 60 minutes at 144°C.

The mechanical properties which are obtained are set out in the following Table XXV B.

J3880 TABLE XXV Β Properties Control (SBR 1712) SBR of the test 2 Modulus at 100% elongation (kg/cm ) 16 14.9 2 Modulus at 3G0& elongation (kg/cm ) 67.5 58 Hysteretic loss at 60°C 29 24.6 Index of coefficient of friction at 20°C (SRT) 100 84 Scott rupture index -elongation at break (%) 570 540 -breaking force (kg/cm ) 231 222 -Shore hardness A 1 62 60 SBR 1712 is a copolymer of butadiene-styrene with 23.5% of styrene, 15-16% of 1,2,60% of 1,4-trans,37.5 parts of aromatic oil.

It can be seen that the elastomer according to the invention has properties substantially equal to those of a conventional copolymer.

It is therefore capable of being used as the principal component of a mixture serving for the manufacture of pneumatic tyres.

Example 26 Six butadiene-styrene copolymers were prepared.

The copolymerisation was effected in a reactor under inert atmosphere - 61 (rectified nitrogen) at 80°C, in the presence of heptane as solvent. The ratio by weight of monomers to solvent was 1:5. The reaction was stopped when conversion reached 80%. The six test conditions and the results obtained are set out in Table XXVI. 880 - 63 Using test elements of the copolymer of test 5 and natural rubber (NR), loaded in accordance with the formulation of Example 25, but not vulcanised, force-elongation measurements (measurement of the green strength) were carried out at °C. The force-elongation measurements were carried out on dumb-bell“test elements with a thickness of 2.5 mm and effected with the assistance of an Instron electronic dynamometer 24 hours after moulding and with a traction speed of 10 cm/min. The results obtained are represented in the accompanying figure of which the ordinates represent the force exerted in g/mtn and the abscissae represent the elongation (in 3>). It is seen that the co-polymer prepared according to the invention has a resistance to elongation which is similar to that of natural rubber.

Example 27 Continuously introduced into a reactor was a mixture of toluene, butadiene and styrene in proportions such that the ratio by weight of monomers to solvent was 1:5 while the butadiene/ styrene ratio was 3.

Ba[Al(C2H5)4]2 and C2Hg(0CH2CH2)20Li were also continuously introduced in quantities such that their - 64 sso molar ratio was 0.5. The ratio of flow was such that there were in the reactor 1000 micromoles of BafAl(CgHg^l2 per 100 g of monomers and an average residence time in the reactor of 1 hour. The copolymerisation was effected at 90°C and the conversion reached 65%. The copolymer formed was continuously recovered at the outlet from the reactor. This copolymer contained 15% by weight of styrene and had an inherent viscosity of 1.6. The content of 1,2-chains was 3% and the content of 1,4- trans chains was 83%.

Example 28 100 ml of heptane as solvent and 13.6 g of butadiene were introduced into a 250 ml Steinie flask under the rectified nitrogen pressure. BafAl (C2Hg)4l2 f (C2Hg)2NCH2CH20Li as catalyst system was then added, after which the flask was placed in a tank thermostatically controlled at 80°C, in which it was agitated.

On completion of the reaction, when the conversion reached 80%, the polybutadiene which had formed was recovered.

The results are set out in Table XXVIII. - 66 so --: .Example 29 A test was carried out, repeating the operational procedure of Example 28 and using similar conditions, except that the catalyst employed was Ba[Al(C2H5)4]2 +- C2H5(0CH2CH2)20Na The results are set out in the following Table XXIX. - 67 ^2880 •σ <4 P Ρ c OJ P ω P c σ o c ta sP P c Φ sΦ P* TABLE XXIX o •Γ φ P ε o 14 P ω ce x: co P w >) r— (4 P Π3 ta z © CM CM □X o CM X u © tn CM to □X CM O 380 - 68 Example 30.

A test was carried out, repeating the operational procedure of Example 29 using similar conditions, except that the catalyst system used was Ba[/Vl(C2H5)4] 2 4- C2H5(0CH2CH2)a0Li.

The results are set out in the following Table XXX. - 69 438S0 TABLE XXX 880 - 70 The words Santoflex, Philblack, Santocure and Instron are .

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Claims (15)

CLAIMS:

1. A process of homopolymerization of a conjugated diene or of copolymerization of conjugated dienes with one another and/or with an aromatic vinyl compound, at a temperature of from 50° to 120°C in the presence of a catalyst system which consists only of the reaction product of (a) an organic compound of a metal of Group IIIA of the Periodic Table of Elements according to the Mendeleev classification, conforming to one of the following formulae: Me 1 M R 1 R 2 R 3 R 4 Μθ 2 [μ r 1 r 2 r 3 r 4 ] 2 M R 1 R 2 R 3 Me 1 0 M R 1 R 2 • 1 2 in which Me represents an alkali metal atom, Me represents an alkaline earth metal atom, M represents a metal of the Group IIIA of the Periodic Table of Elements according to the Mendeleeve 12 3 classification, R , R , and R each represents an alkyl or aralkyl radical and R represents an alkyl radical, an aralkyl radical, or the radical XB in which X represents oxygen, sulphur,or NB where N is a nitrogen atom,and B represents an alkyl radical, an aralkyl radical, or the radical M(R 3 R 3 ), in which R 3 and R 3 each represents an alkyl or aralkyl radical, with (b) one or more electron donor compounds which contain one or more of the atoms, oxygen, sulphur, nitrogen and phosphorus, which compounds are aprotic polar compounds, protic polar compounds, or compounds vzhich are the reaction product of a protic polar compound vzith an alkali or alkaline earth metal, the catalyst system being the reaction product of component (a) with component (b) only and either being preformed by the reaction of components (a) and (b) at a temperature in the range 20 to 100°C,or being formed jn situ by the addition of components (a) and (b) to the monomer reaction mixture.

2. A process as claimed in Claim 1 in which the electron donor compound or compounds is an ether, thioether, tertiary amine, a phosphorus-containing compound, a ketone, nitrile, aldehyde, ester,amide, sulphoxide, alcohol, thiol, phenol, water, a primary or secondary amine, the reaction product of an alcohol ? thiol, phenol, or primary or secondary amine, with an alkali or alkaline earth meta1 ? or a compound having one of the formulae: R(0 CH 2 CH 2 ) 0 Me 1 , (R) 2 N CH 2 CH 2 0 Me 1 in which Me^ represents an alkali metal atom, R represents an alkyl radical, and n is an integer.

3. A process as claimed in Claim 1 or Claim 2 in which the electron donor compound is tetrahydrofuran, lithium isopropylate, water, methanol, acetone, acetonitrile, hexamethyl phosphorotriamide, - 73 42880 Ν,Ν,Ν 1 ,Ν 1 -tetra-methyl ethylene diamine, barium nonyl phenate, lithium alcoholate of ethyl diglycol, or Ν,Ν, - diethylamino -2 ethanolate of lithium.

4. A process as claimed in any preceding claim in which the 5 molar ratio of the electron donor compound or compounds to the organic compound of the metal of Group IIIA is from 0.01 to 100. 5. 8, any Test of Example 9, Example 10, any Test of Example 11, either Test of'Example 12, either Test of Example 13, Example 14, t Example 15, either Test of Example 16, any of Examples 17 to 19, either Test of Example 20, either Test of Example 21, Examples 22 to 24, the copolymer of Example 25, any Test of Example 26, 5 is the reaction product of Li [Al^Hg)^ barium nonyl phenate and lithium isopropylate.

5. A process as claimed in any preceding claim in which the organic compound of the metal of Group IIIA is a compound of

6. A process as claimed in Claim 5 in which the aluminium or boron compound is Ba[/Vi (C 2 Hg) 4 l 2 , Li^Sl(CgHg^OAl (CgHg)^, A1(C 2 H 5 ) 2 , Ba[Al(i-C 4 H 9 ) 4 ] 2j Sl f A1 (C 2 H 5 ) 4 ] 2 , Ca[Al(C 2 H 5 ) 4 ] 2 , Ll ' ί Α1 < ε 2 Η 5)Λ Na[AI(C 2 H 5 ) 4 ], k[a1(C 2 H 5 ) 4 ], LiOAl(C 2 H 5 ) 2j NaOAl(C 2 H g ) 2 , B(C 2 Hg) 3 or LiB(C 2 H 5 ) 3 C 4 H 9 .

7. A process as claimed in claim 1 in which the catalyst system 20 is the reaction product of Ba[Al(C 2 Hg) 4 J 2 and tetrahydrofuran, lithium isopropylate, Ν,Ν,Ν 1 ,Ν'-tetramethyl ethylene diamine, hexamethyl phosphorotriamide, the lithium alcoholate of ethyl diglycol ; or lithium N,N - diethylamino - 2 - ethanol ate

8. A process as claimed in Claim 1 in which the catalyst system

9. A process as claimed in Claim 1 in which the catalyst system is the reaction product of Al(C 2 Hg) 3 , barium nonyl phenate and lithium isopropylate.

10. Or any of Examples 27 to 30. 15. A homopolymer or copolymer of a conjugated diene when prepared by a process as claimed in any preceding claim. 16. Rubber articles comprising a homopolymer or copolymer as claimed in Claim 15. 10 10. A process as claimed in Claim 1 in which the catalyst system is the reaction product of LiOAl(C 2 Hg) 2 and barium nonyl phenate. 10 aluminium or boron.

11. A process as claimed in Claim 1 in which the catalyst system is the reaction product of Li8(C 2 Hg) 3 C 4 Hg and barium 15 nonyl phenate.

12. A process as claimed in any preceding claim in which the conjugated diene is butadiene.

13. A process as claimed in any preceding claim for the preparation of a copolymer in which the aromatic vinyl compound 20 is styrene.

14. A process for the preparation of homo-polymers of conjugated dienes or copolymers of conjugated diene with one another and/ - 75 42880 or with aromatic vinyl compounds substantially as herein described with reference to any of Tests 1 to 3 of Example 1, any Test of Example 2, any Test of Example 3, Example 4, any Test of Example 5, either Test of Example 6, Example 7, either Test of Example

15. 17. Pneumatic tyres and pneumatic tyre treads comprising a homopolymer or copolymer as claimed in Claim 15.