NO145341B - PROCEDURE FOR POLYMERIZATION OR COPOLYMERIZATION OF CONJUGATED DIENES WITH OTHER CONJUGATED DIENES OR VINYLAROMATIC COMPOUNDS, AND CATALYST MIXER FOR EXECUTION OF THE PROCEDURE - Google Patents

Description

The present invention relates to a method by polymerization of conjugated dienes or copolymers of low conjugated dienes, either with each other or with vinyl aromatic compounds with a very low content of 1,2 or 3,4 bonds and a high content of 1,4 -trans bonds, while maintaining the elastomeric character, as well as a Jtåtalyzator for use in the method.

A number of catalytic systems are known which allow the preparation in solution in hydrocarbon environments, polymers of di-

ner with high stereospecificity, namely a high content of cis-

1,4 (example: polybutadiene, polyisoprene), or of trans-1,4 or even of 1,2 or 3,4 linkages. The polymers produced in this way with a high content of trans-1,4 (greater than 9596) have a very strong tendency to crystallize at ordinary temperatures. They behave more like plastic materials than like elastomers, and for that reason they cannot be used as the main component in mixtures used for the production of elastic objects, particularly pneumatic tires.

It is likewise well known that polymers of conjugated dienes

and copolymers of conjugated dienes, either with each other or with vinylaromatic compounds prepared in hydrocarbon mil-

using lithium-containing catalytic systems do not have high steric purity. Namely, with catalytic lithium-containing systems, the obtained polymers and copolymers, at viscosities of 2 or 3, have a content of 1,2- or 3,4-bonds in the diene part which is always greater than 6% and a content of trans-1 ,4 bonds which are always lower than 60%. These contents are sole-

as follows:

For polybutadienes and butadiene copolymers:

45 - 55% of trans-1,4 linkages

7 - 12% of 1,2 bonds

40 - 45% of cis-1,4 bonds.

For polyisoprenes and isoprene copolymers:

10 - 25% of trans-1,4 linkages

6 - 10% of 3,4 bonds

70 - 85% of cis-1,4 bonds.

For higher viscosities, at least equal to 6, one finds in the case of isoprene and its copolymers that the content of cis-1,4 bonds increases up to 95% at the expense of the content of trans-1,4 bonds and 1,2- or 3,4 bonds.

With lithium-containing catalytic systems, within the above-mentioned limits, the quantity ratio of 1,2- or 3,4-bonds in relation to 1,4-bonds can be increased by using certain tricks, e.g. by changing the polarity of the reaction medium.

However, there is no method to vary within

wide limits the content of 1,4-trans bonds while maintaining a very low content of 1,2- or 3,4 bonds.

The purpose of the present invention is to eliminate this disadvantage by providing a catalytic mixture which allows to obtain diene polymers or copolymers with a high content. of 1>4-iron T bonds in the dienic parts of these compounds, either over the entire length of the polymer chain or copolymer chain or only over part of this length, and with a very low content of 1,2- or 3, 4 bonds.

The invention thus relates, on the one hand, to a process for the polymerization or copolymerization of conjugated dienes with other conjugated dienes or vinyl aromatic compounds to give elastomeric polymers containing more than 70% 1,4-trans bonds and a content of 1,2- or 3, 4 bonds of up to 5%, in the presence of a catalytic mixture comprising _ an organo-lithium initiator and a compound of barium or strontium, and it is characterized by the use of a catalytic mixture which also comprises an organometallic compound. .., deise of metals from groups UB or HIA in Hendelejev's periodic table.

Another object of the invention is to provide a catalytic mixture for use in the method.

The present invention thus provides a catalytic mixture for the polymerization of conjugated dienes or for the copolymerization of conjugated dienes with other conjugated dienes or vinyl aromatic compounds, which mixture comprises an organolithium initiator and a barium or strontium compound, and is characterized by the fact that the mixture further contains an organometallic compound of metals from groups UB or HIA

in the periodic table.

By "organo-lithium initiator" is understood here primarily all organometallic compounds containing one or more carbon-lithium bonds, secondarily all ion radical adducts of lithium and certain aromatic polynuclear hydrocarbons,

thirdly, the metallic lithium itself, and finally oligomers formed by the addition of lithium to conjugated dienes or substituted styrenes.

As representative examples of organo-lithium initiators, the following compounds can be mentioned: Aliphatic organo-lithium compounds, such as ethyllithium, n-butyllithium, isobutyllithium, sec.-butyllithium, tert-butyllithium, isopropyllithium, n-amyllithium, isoamyllithium, alkenic organolithium compounds, such as allyllithium, propenyllithium, isobutenyllithium, "living" polybutadienyllithium polymers, polyisopropenyllithium, polystyryllithium, dilithium polymethylenes, such as 1,4-dilithiumbutane, 1,5-dilithiumpentane, 1-20-dilithiumeicosane, aromatic organolithium compounds, such as benzyllithium, phenyllithium, 1,1-diphenylmethyllithium, polylithium compounds resulting from the reaction of metallic lithium with ethylenic aryl-substituted compounds, such as 1,1-diphenylethylene, trans-stilbene, tetraphenylethylene, radical ions such as lithium naphthalene, lithium anthracene, lithium chrysene, lithium dephenyl, as well as derivatives substituted with one or more alkyl groups.

With regard to the components included in the composition of the cocatalyst, "barium or strontium compound" is understood to mean H2Ba and H2Sr hydrides, salts of mono- or polyfunctional organic acids with formulas (R-COO)2Ba or-Sr, R1- (COO)2Ba or-Sr in which R and R^ are organic radicals, the first monovalent, the second divalent, which do not carry other functions capable of inactivating the organolithium initiator, and the corresponding thioacids, also corresponding mono- or polyfunctional alcoholates and thiolates, corresponding mono- or polyfunctional phenates and thiophenates, salts of alcoholic acids and phenolic acids of barium or strontium and the corresponding thio products, barium or strontium p-diketonates, such as reaction products of barium or strontium with acetylacetone, dibenzoylmethane, thenoyltrifluoroacetone, benzoyltrifluoroacetone, benzoylacetone, organic barium or strontium derivatives, such as derivatives of 1,1-diphenylethylene, 1,2-acenaphthylene, tetra-phenylbutane, a-met ylstyrene or such derivatives as diphenyl-barium or -strontium, barium- or strontium-bis-cyclopentadienyl, barium- or strontium-trialkylsilyls, barium-

or strontium-triphenylsilyl and mixed organic derivatives, such as phenylbarium iodide, methylstrontium iodide, barium or strontium salts of secondary amines, cetyl metals, such as barium or strontium benzophenone, barium or strontium

cinnamon and corresponding alkyl products as well as sulphurised homologues, radical ions of barium or strontium such as those of naphthalene, anthracene, chrysene, diphenyl etc.

As representative examples of organometallic compounds from group II B or III A, one can mention: Dialkylzinc or dialkylcadmium, such as diethylzinc, diethylcadmium, halogenated or non-halogenated organoaluminum compounds such as triethylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum dichloride, ethylaluminum sesquichloride, methyl aluminum -sesquichlorid, dialkylaluminum hydrides such as diethylaluminum hydride, diisobutylaluminum hydride, etc.

The cocatalytic system can be formed in accordance with the following two preferred variants: According to the first variant, the various components of the cocatalytic system are brought into solution separately in a hydrocarbon solvent which is preferably identical to that which is to be used later during polymerization - or the copolymerization reaction, so that they can be introduced separately into the reaction system. According to the second variant, the cocatalyst is "preformed" by mixing the barium or strontium compound and the organometallic compounds of metals from group II B or III A in a hydrocarbon solvent. These preformed cocatalysts have the property that they are more soluble in hydrocarbon solvents and that they retain their high activity for a longer period of time. This mixture of the two components of the co-catalyst is indeed accompanied by a complete or partial dissolution of the barium or strontium compound and especially of the compounds which are normally not soluble in hydrocarbon environments, such as hydrides, acetyl-acetonates and the majority of alcoholates. It results from this that the use of the preformed cocatalytic system is particularly advantageous. According to the first variant, the components of the co-catalytic system are introduced in solution in a hydrocarbon solvent separately into the reaction medium, either at the beginning of the reaction together with the organolithium initiator to form "in situ" the catalytic mixture, or during the course of the polymerization in small doses or all at once or one after the other in any order. This method of working is used in principle for the barium or strontium compounds that are loose

directly in the relevant solvents.

It is clear that only from the moment when the entire co-catalytic system that is installed in the reaction environment has reacted with organo-lithium compounds can the desired effect be exploited, i.e. increase the content of 1,4-trans bonds and decrease the content of 1,2- or 3,4 bonds. It appears from this that when the entire co-catalytic system is present from the beginning of the reaction, products with a very high content of 1,4-trans bonds and a very low content of 1,2- or 3,4-bonds over the entire length will be obtained of the polymer or copolymer.

On the other hand, when the components of the cocatalytic system are introduced into the course of the reaction either simultaneously in small doses or one after the other, one can prepare the products in different steric configurations, the addition of the cocatalytic system causing the formation of products rich in trans- 1,4 bonds and poor in 1,2 or 3,4 bonds.

When, according to the second variant, the cocatalytic system is used in "preformed" form, it can be added to the organo-lithium initiator either at the beginning of the reaction to obtain a product with a constant content of 1,4-trans bonds from one end to the other end of the macromolecular chains, or in the course of the reaction in one or more doses, depending on whether one wishes to achieve a change of the steric configuration only from this addition of, or whether one wishes to achieve the change of the steric configuration in a progressive manner.

The catalytic system according to the invention has an activity

which extends over a large concentration range of the catalyst and over a large range of quantity ratios of components in the catalytic system.

Depending on the reaction conditions (the nature of the solvent,

of the monomer or monomers present, the temperature, etc.) the molar ratio of each of the constituents of

the co-catalytic system, and between one of these constituents and either the organo-lithium initiator or the lithium polymer or the "living" copolymer be different to achieve specific contents of trans-1,4- and 1,2 bonds. One must therefore set these different molar ratios depending on the conditions under which one works and depending on the desired steric configurations. In this way, e.g. these contents are continuously regulated to between 45% and 95% trans-1,4 bonds and from 12% to 3% of 1,2 bonds in the case of polybutadiene or butadiene copolymers and from 25% to 45% trans- 1,4 linkages and from 10% to 5% of 3,4 linkages in the case of polyisoprene and isoprene copolymers.

It appears from this that the optimum concentration of a constituent of the catalyst is dependent on the concentration of the other constituents of the catalyst. One can, however, mention certain limits for different molar ratios between which an optimal content of "trans-1,4-bonds" and a minimal content of 1,2- or 3,4-bonds will be achieved.

These limits are as follows:

and preferably within the limits:

where R Me HIA is an organometallic compound of a UTA metal, and R Me UB is an organometallic compound of a UB metal.

Aromatic lithium is understood to mean the amount used of the active organolithium compound which represents the difference between the total amount actually introduced and the minimum required to achieve a beginning of the polymerization (amount which, among other things, serves to neutralize the remaining impurities of reaction environments).

In the present invention, products are obtained

with a very high content of 1,4-trans bonds and a low content of 1,2- or 3,4-bonds such as yet retain their elastomeric character, and a process by which monomers are polymerized and copolymerized to form these products.

According to a first embodiment, a product with a high content of 1,4-trans bonds and a low content of 1,2- or 3,4-bonds is obtained over the entire length of the polymer or copolymer by introducing the catalytic mixture at the beginning of the reaction .

According to another embodiment, the method leads to the formation of polymers and copolymers with different or progressive steric configurations by adding the specified parts of the catalytic mixture to the reaction medium in one or more doses simultaneously or separately.

The method according to the invention relates to polymer

rization of dienes and copolymerization of dienes and vinyl aromatic compounds.

As representative examples of dienes, one can mention conjugated dienes, such as 1,3-butadiene, isoprene, 2,3-dimethyl-butadiene-1,3, pentadiene-1,3, methyl-2-pentadiene-1,3 and 2, 4-hexadiene.

As representative examples of vinyl aromatic compounds, one can mention: styrene, ortho-, meta-, para-methyl-styrene or the commercial "vinyl-toluene" mixture, di- and polymethylstyrenes, p-tertiarybutylstyrene, vinyl naphthalene, methoxystyrenes , halogenated styrenes, vinylmesitylene, vinyldurol, divinylbenzene.

Products with a high content of trans-1,4 bonds produced according to the method on the basis of the lithium catalytic system - have the property that they are elastomeric and thereby suitable for use in the form of a mixture to produce rubbers, in contrast to other polymers with a very high purity of trans-1,4 bonds which were produced until now by means of other catalytic systems, which products are plastic and brittle at ordinary temperature as they are crystallized.

Mixtures in a non-vulcanized state obtained with products obtained by the method have, due to their high content of trans-1,4 bonds, improved properties, namely increased strength in the raw state "green-strength"), very high breaking strength and elongation, and better dimensional stability.

These mixtures with improved properties thus lead to better rubbers which can be used in particular for the production of pneumatic tyres.

The following examples shall illustrate the invention:

EXAMPLE 1

Copolymerization of butadiene-styrene by means of

the system n- butyllithium cinnamon- barium- triethylaluminum.

Preparation of the cocatalyst.

As the cinnamon-barium complex was soluble in toluene, it was possible to study the effect of each component of the co-catalyst, the Ba/Al ratio not being fixed due to the solubility in the reaction medium.

The cinnamon-barium complex is prepared in 250 cm 3 Steinie bottles in a nitrogen atmosphere by dissolving 0.1 mol of cinnamon (diphenyl-1,6-pentadien-1,4-one-3) in 50 cm 3 tetrahydrofuran in which is suspended 1.5 g of finely divided metallic barium. After stirring this mixture at ambient temperature for 20 hours, a red solution is obtained which is filtered. This solution is evaporated under vacuum. The resulting brown precipitate is collected after two washes with heptane in toluene, still under a nitrogen atmosphere, to give a 0.025 M barium solution.

Copolymerization

Two series of copolymerization experiments are carried out by introducing into Steinie flasks of 250 cm 3 as a catalytic system: - varying amounts of 0 to 200.10 — 6 mol of triethylaluminium.

- 50.10 mol of active n-butyllithium as defined above.

In the first series of experiments, no barium compound is used. IN

— 50.10 mol of cinnamon-barium are introduced into each bottle in the second series of experiments.

The copolymerization is carried out in the presence of cyclohexane (123 g per 250 cm Steinie bottle) with 9.225 g of butadiene and 3.075 g of styrene per bottle.

The reaction bottles are placed in a thermostatic container at 70°C

and they are stirred for varying times, so that samples are obtained that correspond to increasing conversion percentages.

Tables IA and IB show the results obtained at 50% conversion.

First series ([Ba] = 0) ...

By studying these results, one ascertains the effect of each of the introduced compounds on the steric configuration of the obtained copolymers (% of trans-1,4-bonds and % of 1,2-bonds) and also the effect on the reaction kinetics, the obtained specific viscosity and the mode of introduction of the styrene.

With regard to the effect on the steric configuration, and in particular on the content of trans-1,4-bonds and 1,2-bonds, it can be seen that the expected effect is only achieved when the three components of the catalytic system are present simultaneously in the reaction environment . If one of them is absent, a steric configuration is obtained that is very similar to that obtained with n-butyllithium used alone.

EXAMPLE 2

Polymerization of butadiene using n-butyllithium and av

a "preformed" cocatalytic system: barium acetylacetonate

- trialkylaluminium.

Preparation of cocatalysts.

Barium acetylacetonate is produced directly by the reaction of acetylacetone and barite in anhydrous methanol.

The product formed is insoluble in hydrocarbons. A soluble cocatalytic system is obtained by mixing in a nitrogen atmosphere for 15 minutes at ambient temperature barium acetylacetonate and trialkylaluminum in the presence of a hydrocarbon solvent.

Three systems are produced:

System A: After 5.32 millimoles of barium acetylacetonate are suspended in 170 g of normal heptane, 23.4 millimoles of commercial triethylaluminum with a titer of 0.92 m are added. After stirring

- 2

if a clear solution with a titer of 2.9.10 m of barium and

_ 2

11.3.10 m of aluminium.

System B: To 5.85 millimoles of barium acetylacetonate in suspension in 170 g of toluene, 26.3 millimoles of commercial triethylaluminum with a titer of 0.92 m are added. After stirring, a clear solution with a titer of 3.2.10 _ 2 m of barium and 11.6.10 <2>m of aluminium.

System C: To 5.85 millimoles of barium acetylacetonate in suspension in 170 g of heptane, 25.1 millimoles of commercial triisobutylaluminum with a titer of 0.79 m are added. After stirring, a clear solution with a titer of 2.4 is obtained.10 m of barium and 11, 8.10 m of aluminium.

Polvmerisas ion

These three catalytic mixtures are used in combination with normal butyllithium to polymerize butadiene dissolved in heptane (first test series) or in toluene (second test series).

These series of experiments are carried out in 250 cm 3 Steinie bottles closed with a rubber stopper through which the various ingredients required for polymerization are introduced. In these bottles, 123 g of solvent (heptane or toluene) are introduced under nitrogen pressure (approx. 1 bar), then 12.3 g of butadiene, then one of the aforementioned cocatalytic systems and finally n-butyllithium. The bottles are then placed in a thermostatic container at 60°C, where they are stirred for three hours.

At the end of these three hours, the polymerization is interrupted by introducing into each container 0.25 cm 3 of a solution of methanol in toluene at 60 g/litre. A phenolic antioxidant is also introduced ("Agerite Geltrol" manufactured by Societe Vånderbilt)

(2 cm 3 of a solution of 246 g/litre).

The polymers are then recovered by coagulation using a methanol-acetone mixture and dried in a vacuum in a drying cabinet (80°C - 0.2 bar - 15 hours).

On the samples thus obtained, the obtained conversion percentages of butadiene to polybutadiene, the specific viscosities obtained at 25°C in a solution of 1 g/liter in toluene, and the steric configurations are determined.

The results obtained are shown in table IIA and UB.

First series (solvent heptane)

2nd series (solvent toluene)

You add next to the quantities indicated here, calculated

as active, additional amounts of n-BuLi intended to remove contaminants in reaction environments.

EXAMPLE 3

Polymerization of butadiene using n-butyllithium and

a "preformed" cocatalytic system: dibenzoylmethane-barium - triethylaluminum.

Preparation of the cocatalyst.

Dibenzoylmethane barium chelate is produced directly from dibenzoylmethane and barite in an anhydrous methanol environment.

The product formed is insoluble in hydrocarbons. The cocatalytic system is prepared by mixing under a nitrogen atmosphere in suspension in 123 g of heptane, 5.2 millimoles of dibenzoylmethane barium and 26 millimoles of commercial triethyl aluminum with a titer of 0.84 m. This mixture is heated to 60°C over the course of 1/2 hour under stirring, so that the chelate dissolves. A yellow solution is then obtained which remains clear after it has been brought back to ambient temperature. It has a titer of approx. 3.102

_ 2

m of barium and 15.10 of aluminium.

Polymerization ion.

This cocatalytic mixture is used in combination with normal butyllithium to polymerize butadiene in solution in heptane.

Polymerization conditions are the same as described previously (Steinie bottles of 250 cm , 123 g of heptane and 12.3 g of butadiene,

3 hours at 60°C).

Results obtained:

EXAMPLE 4

Copolymerization of butadiene and styrene using n-butyllithium and the "preformed" cocatalytic system in example li

The same cocatalytic mixture dibenzoylmethane-barium-triethylaluminum is used.

Copolymerization is carried out in Steinie bottles of 250 cm 3 as before under the same experimental conditions.

One introduces into each reaction bottle:

- 123 g of heptane

- 12.3 g of monomers: 9.225 g of butadiene and 3.075 g of styrene (i.e.

25% of the allocation)

- 65.10~^ mol active n-BuLi

- 60.10~<6> mol of the co-catalytic complex calculated on barium (i.e. accompanied by 300.10<->^ mol Al).

The results obtained at 80°C depending on the duration of the reaction are as follows:

The final copolymer obtained in the course of 18 hours had a specific viscosity of 1.1.

EXAMPLE 5

Copolvmerization of butadiene-styrene using the system n-butyllithium- bariumnonylph enolabdiethylzinc or triethylaluminum.

Preparation of the cocatalyst.

Barium nonylphenolate is prepared by contacting nonylphenol (0.02 mol) and barite (0.01 mol of Ba(OH) 2 ) in the presence of 100 cm 3 toluene. The mixture is stirred hot (60-80°C) until the barite completely disappears. Approximately half of the solvent is evaporated under vacuum in such a way that all the water formed is swept away, and the concentrated solution is then made up to 100 cm 3 using fresh toluene. A solution of anhydrous barium nonyl enolate in toluene is thus obtained, with a titer of approx. w/10.

Copolymerization.

You copolymerize in Steinie bottles of 250 cm 3 butadiene and styrene into which you introduce:

To complete the catalytic system, add:

- either 100.10~^ mol of triethylaluminium

- or 100.10" mol of diethyl zinc.

When it comes to the comparison experiment (blind sample), neither of these two compounds is added.

The copolymerization is carried out at 70°C for varying periods of time indicated in table V, where the results obtained are also indicated.

EXAMPLE 6

Copoly<y>merization of butadiene-styrene and copolymers having two different sequences of steric configuration.

This copolymer is obtained by adding in the course of the polymerization one of the 3 components of the catalytic system, namely: triethylaluminium, normally butyllithium and the barium compound are added together at the beginning of the reaction.

In a 250 cm 3 Steinie flask, which is kept under a nitrogen atmosphere, 123 g of heptane, 9.225 g of butadiene, 3.075 g of styrene, 50.10~<6> mol of active n-butyllithium and 50.10~<6> mol of barium nonyl enolate prepared as in the preceding example.

Copolymerization is carried out for 1 1/2 hours at 70°C.

54% turnover is achieved. The copolymer contains 16% styrene and has the following steric configuration: 53% trans-1,4- and 10% 1,2-bonds (in the polybutadiene part).

One then adds 100.10~^ moles of triethyl aluminum per Steinie flask, and continue the copolymerization at 70°C over the course of 1 1/2 hours. The final copolymer contains 14% styrene. Also, an average of 61% of the butadiene is chain-linked in 1,4-trans bonds and 8% in 1,2-bonds. The total conversion percentage is 76%.

This means that the resulting copolymer has two sequences:

- the first, which represents 71% of the total copolymer, contains on the one hand 16% styrene and 53% trans-1,4, on the other hand 10% 1,2 bonds for the steric configuration

of the polybutadiene part.

- the other, which represents 29% of the total copolymer, contains on the one hand 9% styrene and on the other hand 79% trans-1,4 and 4% 1,2 bonds in the polybutadiene part.

EXAMPLE 7

Polymerization of butadiene using n-butyllithium and a "preformed" cocatalytic system: barium alcoholate - chlorinated or non-chlorinated organoaluminum compound.

Preparation of cocatalysts

Different barium alcoholates and different organoaluminum compounds are used to preform different cocatalytic systems under the following general conditions:

Approximately 2 g of sodium alcoholate are introduced into Steinie flasks of 250 cm 3 under a nitrogen atmosphere. 100 cm3 of heptane is added and then a quantity of alkyl or chloro-alkyl aluminum which is indicated in the following table. The bottles are then placed in a thermostatic container at 60°C, where they are stirred for 6 hours. The barium alcoholate which may not have dissolved is then filtered under a nitrogen atmosphere, and the dissolved barium is dosed. In the following table VIIA you will find for each of the used . alcoholates and organoaluminium compounds the quantity of the introduced product (for 100 cm 3 heptane), the barium titer (in mol/litre) obtained after the dissolution and filtration, as well as the yield of dissolved barium in relation to the introduced amount of barium alcoholate, and the designation of the thus formed co-catalytic system:

Polymerizations.

With these coXatalytislce systems, butadiene is polymerized under the following conditions:

Place in a 250 cm Steinie bottle:

- heptane 123 g

- butadiene 12.3 g

- cocatalytic system 50.10" mol barium

- active n-butyllithium: quantity stated in the following table.

The polymerization reaction is carried out with stirring for 14 hours at 70°C.

The results obtained with different co-catalytic systems are given in Table VII B.

EXAMPLE 8

Polymerization of butadiene using n-butyllithium and a "preformed" cocatalytic system: strontium alcoholate - chlorinated or non-chlorinated organoaluminum compound.

Production of cocatalytic systems.

Identical conditions as in the previous example (except stirring for 7 hours at 70°C instead of 6 hours at 60°C).

The stated quantities also correspond to 100 cm 3 of heptane.

Polymerization

The same conditions as in the previous example, except:

- polymerization for 6 hours at 70°C with 50.10~^ mol strontium alcoholate per reaction bottle.

EXAMPLE 9

Polymerization of butadiene using n-butyllithium and a "preformed" cocatalytic system: Barium hydride organoaluminum compound chlorinated or non-chlorinated.

Preparation of the cocatalytic systems.

The manufacturing conditions are identical to those in example 7

(6 hours at 60°C), but you replace 2 grams of barium alcoholate with 3 grams of barium hydride.

Two series of cocatalytic systems are formed, one in heptane (100 cm 3 per Steinie bottle) the other in toluene (20 cm 3 per bottle).

In the following tables IXA and IXB you will find for each of them

two series the amount of products used per Steinie bottle, the final titer in barium of the solution obtained after filtration, as well as the yield of barium and the name of the product.

Polymerization.

The same conditions as in example 7.

- polymerization at 70°C for 24 hours in "heptane environment.

- amount of BaH2 per reaction flask of 250 cm 3 : 50.10- — 6 mol.

The results obtained, depending on the amounts of n-butyllithium used, are indicated in the following Table IXC.

EXAMPLE 10

Polymerization of butadiene using barium diethylzinc n-butyllithium naphtholate.

Preparation of the catalyst.

Barium naphtholate, produced from commercial naphthenic acid by neutralization with soda ash in an aqueous medium and precipitation with barium chloride, is a salt that is soluble in a toluene medium. A solution of 0.113 mol/litre in barium of barium naphtholate in toluene is therefore used.

Polymerization.

Butadiene is polymerized under the same conditions as before in Steinie bottles of 250 cm 3, 12.3 g of butadiene per 123 g of heptane with 50.10<-6> mol of barium naphtholate and 50.10<->^ mol of active n-butyllithium per bottle over the course of 6 hours at 70°C. The results, depending on the amounts of diethylzinc introduced, are given in Table X.

EXAMPLE 11

Polymerization of isoprene using the system barium-n-butyllithium-nonylfeoioate and diethylzinc or triethylaluminium.

The solution of barium nonylphenolate in toluene is prepared as in example 5.

Isoprene (12.3 g) is polymerized in Steinie bottles of 250 cm in heptane environment (123 g) for 6 hours at 70°C with pr. reaction bottle:

- 50.10~<6> mol active n-Bu/Li

- 0 or 50.10~^ mol of barium nonylphenolate

- 0, 100 or 200.10~<6> mol triethyl aluminum or diethyl zinc.

Table XI compares the impact of the combination of these different additives.

EXAMPLE 12

Copolymerisation of isoprene styrene using the same system as in example 11.

One works under the same polymerization conditions in Steinie bottles of 250 cm in a heptane environment (123 g) with 9.24 g of isoprene and 3.08 g of styrene (25% in relation to isoprene). Copolymerization is carried out for 2 hours at 70°C in the presence of 50.10<-6> mol of active n-BuLi.

EXAMPLE 13

Copolymerization of butadiene-vinyltoluene using the system barium-n-butyllithium-n-nylphenolate-triethylaluminium.

Copolymerization is carried out in bottles of 250 cm 3:

- 9.24 g of butadiene

- 3.08 g vinyltoluene (commercial mixture of 2/3 metamethylstyrene and 1/3 paramethylstyrene)

- 123 g of heptane

— 6

- 50.10 mol active n-BuLi

- 50.10"^ moles of barium nonylphenolate

- 200.10~^ mol triethylaluminium

for 3 hours at 7o°C.

The following results are obtained:

- conversion rate: 64%

- V = 0.97

- 9% vinyltoluene present in the copolymer

- 82% trans-1,4-bonds and 3% 1,2-bonds in the poly-butadiene phase.

EXAMPLE 14.

Copolymerization of butadiene-tertiobutylstyrene using the same system as in example 13.

One introduces per Steinie bottle of 250 cm 3:

- 9.24 g of butadiene

- 3.08 g tertiary butyl styrene (95% para - 5% ortho)

- 123 g of heptane

- 50.10 mol active n-BuLi

- 50.10-^ mol triethylaluminium

and copolymerizes for 5 1/2 hours at 70°C.

The following results are obtained:

- V = 1.12

- 7% tertiary butyl styrene present in the copolymer

- 85% trans-1,4 bonds and 3% of 1,2 bonds.

EXAMPLE 15

Mechanical properties of a mixture for rubber on the basis

of the butadiene styrene copolymer with a high content of trans-^ 1, 4- bonds and a low content of 1, 2- bonds.

1. Preparation of the copolymer.

The catalytic system in example 3 or 4 is used:

- n-butyllithium

- preformed cocatalytic system dibenzoylmethane-barium-triethylaluminum.

The polymerization is carried out in one 10 liter reactor under a nitrogen atmosphere with:

- solvent: heptane: 5040 g

- monomers, 1 . , „, 3

rr,^„„r^v.„v.. /butadiene: 378 g

(.styrene: 126 g

- catalyst: active n-butyllithium: 1.64.10 _ 3 mol

-cocatalytic barium: 1.64.10"<3> mol

system: aluminum: 8.2.10 mol

in the course of 2 hours at 80°C.

The degree of conversion is 75% and the obtained viscosity is 1.4.

A three-chain grafting is then carried out by introducing i

_ 3

the still active medium 1.64.10 mol diphenyl carbonate according to French patent no. 2,053,786. The reaction is allowed to continue for 20 minutes at a temperature of 80°C. Methanol is then introduced to interrupt the reaction and an antioxidant (0.5% by weight in relation to the rubber), and the elastomer (approx. 380 g) is recovered by entrainment of the solvent with water vapor and vacuum drying.

The final viscosity after grafting is 1.9. Mooney viscosity (1+3 at 100°C) is then 45.

The resulting copolymer has the following steric configuration:

- 75% of trans-1,4 bonds *) .. , . , ,

5% of 1,2-bind' ingers^ h per butadiene part

The content of added styrene is 8 1

2. Compound for the rubber industry.

The elastomer described above is used to form a mixture with the following formula:

The same mixture is prepared with a commercial butadiene styrene copolymer (SBR 1500) as a blank sample. With samples of these mixtures in an unvulcanized state, strength-elongation measurements are carried out (measurement of the strength in the raw state).

The following results are held:

The mixture formed with the elastomer according to the invention has better mechanical properties than the blank sample.

The two mixtures are then vulcanized for 60 minutes at 144°C. The obtained mechanical properties are indicated in table XV B. It is noted that the elastomer according to the invention, i.e. SBR, with a high content of 1,4-trans bonds and a low content of 1,2 bonds, has the properties that characterize the rubber and even good rubber when you take into account the achieved value of hysteresis loss.

Claims (6)

1. Process by polymerization of conjugated dienes or by copolymerization of conjugated dienes with other conjugated dienes or vinyl aromatic compounds to give elastomeric polymers containing more than 70% 1,4-trans bonds and a content of 1,2- or 3,4 bonds of up to 5%, in the presence of a catalytic mixture comprising an organolithium initiator and a compound of barium or strontium, characterized in that a catalytic mixture is used which also comprises an organometallic compound of metals from groups UB or HIA in Mendeleev's Periodic Table. 2. Method according to claim 1, characterized in that a mixture of the barium or strontium compound and the organometallic compound of the metals from groups UB or IIIA is added in portions to the reaction environment. 3. Process according to claim 1 or 2 by copolymerization where butadiene is used as the conjugated diene and styrene is used as the vinyl aromatic compound, in the presence of a catalytic mixture comprising n-butyllithium and barium phenolate, characterized in that a catalytic mixture is used which also contains trialkyl aluminum. 4. Catalytic mixture for the polymerization of conjugated dienes or for the copolymerization of conjugated dienes with other conjugated dienes or vinyl aromatic compounds in the method according to claims 1 - 3, comprising an organolithium initiator and a barium or strontium compound, characterized in that the mixture further contains an organometallic compound of metals from groups UB or HIA in the periodic table. 5. Catalytic mixture as stated in claim 4, characterized in that the organometallic compound from group UB or IIIA is selected from zinc or cadmium dialkyls, halogenated or non-halogenated organoaluminium compounds, organic boron compounds, dialkyl aluminum hydrides. 6. Catalytic mixture as stated in claim 4 or 5, characterized in that the components are present in such quantities that their ratio of quantities lies within the following limits: with and preferably within the limits: with: where R Me HIA is an organometallic compound of a HIA metal and R Me UB is an organometallic compound of a UB metal.