DE2449784A1 - Catalyst systems for diene polymers and copolymers - comprising alkali metal deriv. of amine and solubilising agent - Google Patents

Abstract

Homo- or co-polymerisation of conjugated dienes in inert org. solvents is characterised by the use of an alkali metal deriv. of an amine in the presence of a solubilising agent as catalyst. Li alkyl or aryl can be used as catalyst but if a high mol. wt. prod. is reqd., amt. used must be small. Such Li cpds. are deactivated by unavoidable impurities in diene monomers or solvents used. Li derivs. of amines are not affected in this way but are very difficulty soluble in monomers and solvents usually employed. In presence of a solubilising agent, excess can be used and a constant concn. can be maintained in soln. so that reproducible results are easily obtd.

Description

Polymerization and copolymerization of dienes is the subject of the invention is a process for homo- or copolymerization of dienes in inert organic Solvents on alkali metal amides as catalysts in the presence of solvating agents to the alkali metal amides.

It is known to add butadiene to organolithium compounds, e.g. B. of the formula RLi (R = alkyl, aryl) to polymerize. The structure of the Polymers can be obtained by adding Lewis bases, e.g. B. Athern, are influenced (see J. Polym. Sci. 42, 299 (1960); DOS 1 958 650).

In this polymerization is the molecular weight and the microstructure of the polymer depends on the amount of catalyst. If the polymer has a high Should have molecular weight, only very small amounts of catalyst may be used. Organic lithium compounds are caused by impurities in the monomer and in the Deactivated solvent.

Small amounts of such impurities are always present.

Their amount cannot be kept constant. Therefore fluctuates the effective catalyst quantity from polymerization batch to polymerization batch and thus also the molecular weight and the microstructure of the polymers. In particular Polymers with high molecular weights that contain small catalyst concentrations demand, can practically not be produced reproducibly.

It is also known to conjugate dienes in bulk or in inert solution to polymerize on lithium amides (see US Pat. No. 2,849,432). Lithium amide is in the monomers and the usual inert organic solvents only with great difficulty soluble. Since only dissolved lithium amide acts as a catalyst, the effective amount of catalyst is given by the solubility of the lithium amide in the polymerization system. In general one works with an excess of lithium amide, so that consumed by side reactions, dissolved lithium amide is replaced by dissolving the appropriate amount. the The amount of catalyst is therefore kept constant here, so that the polymer is reproducible but the amount of catalyst is also unchangeable Value set so that the product properties are also set and unchangeable are.

The present invention is based on the knowledge that one the effective amount of alkali amide catalysts in polymerization and copolymerization of conjugated dienes in inert organic solvents within wide limits can be set at will if you add a solvation agent for the amide. By The amount and type of solvating agent will determine the amount of amide that will be can solve in the polymerization approach. If there is an excess of amide here, then dissolved amide consumed by side reactions can be removed by subsequent dissolving of a corresponding Quantity to be replaced. The active amount of catalyst is therefore constant. By crowd and type of solvating agent can be the concentration of the active catalyst reproducibly adjusted and thus molecular weight and microstructure of the polymer can be varied reproducibly. Since the solubility of the amide too is still temperature dependent, by changing the reaction temperature during the polymerization can still be exerted on the polymer.

The invention accordingly provides a method for homo- and for Copolymerization of conjugated dienes in inert organic solvents is characterized in that the catalyst used is an alkali metal amide in the presence of a solvating agent used for the alkali amide.

For the process, conjugated dienes are particularly useful as monomers 4-8 carbon atoms, such as butadiene and isoprene, are suitable. These can serve can also be copolymerized with vinyl aromatic compounds such as styrene. That The ratio of the diene units and the vinyl aromatic units in the polymer is arbitrary. In general, however, not more than 40% of the monomer units should be in copolymer units aromatic vinyl compounds.

Particularly suitable alkali amides are those of the formula wherein R = C3 - C20 alkyl, C5 - C7 cycloalkyl, C6 - C10 aryl, R '= R, C1 - C20 alkyl, C5 - C7 cycloalkyl, C6 - C10 aryl and Me is lithium, sodium or potassium.

Lithium dipropylamide, lithium dibutylamide and lithium dicyc are particularly suitable lohexylamide, lithium diphenylamide, N-lithium-N-methylanilide, N-lithium-N-ethylanil id, sodium dipropylamide, potassium dibutylamide and N-sodium-N-methylanilide. Such Amides Can in a manner known per se by reacting alkali metal alkyls or alkali naphthalene with the corresponding secondary amines in organic solvents getting produced.

Solvating agents are preferably ethers and tertiary amines.

Dialkyl ethers with 2-6 carbon atoms are particularly suitable the alkyl groups such as diethyl ether, di-n-propyl ether, diisopropyl ether, di-n-butyl ether or cyclic aliphatic ethers such as tetrahydrofuran, dioxane or diether such as Dimethoxyethane. Tertiary amines are in particular trialkylamines, preferably with 1 - 4 carbon atoms such as trimethylamine, triethylamine, tertiary aliphatic diamines such as NNNtNt-tetramethylethylenediamine or cyclic tertiary amines such as N-methylmorpholine or N-phenylmorpholine.

The amount of solvating agent is depending on the structure or Viscosity of the polymer to be produced 0.01-30 percent by weight, based on Monomers. The alkali amide is generally added in such an amount that still undissolved sediment is present (0.01-1% by weight, based on monomer). The polymerization itself is carried out in the usual inert organic solvents, i.e. aliphatic or aromatic hydrocarbons. Particularly suitable solvents are n-hexane, cyclohexane, benzene, toluene, xyl oil or mixtures from it. The reaction temperature is generally from about 0 to about 60 ° C., preferred 15 to 400C.

The polymerization process is used in that for organometallic catalysts carried out in the usual way. Preference is given to making a solution of the alkali metal amide in a mixture of solvent and solvating agent and adds to this Solution with exclusion of air and moisture to the monomers.

After the polymerization has ended, the catalysts in the can be deactivated in the usual way. The polymer obtained can be precipitated or can be obtained by steam distillation.

The products obtained are vulcanizable rubbers.

Examples In the following examples, anhydrous solvents were used worked under a pure nitrogen atmosphere. The polymers obtained are made from the polymerization solution isolated by precipitation with methanol and treated with 2,21-methylene-bis-6-tert.

butyl-4-methylphenol stabilized.

Example 1 A Preparation of the catalyst To 400 ml of toluene 4 ml of n-butyl lithium solution and 1.2 ml of dipropylamine are added and the mixture is 15 Stirred minutes at 2o0C with exclusion of air and moisture.

A solution of lithium dipropylamide is obtained.

B Polymerization 1 liter of toluene, 20 ml Triethylamine and 200 ml of butadiene given and 20 hours at a temperature of Stirred at 20 - 40 ° C.

After working up, a polybutadiene is obtained in almost 100% yield obtained with the intrinsic viscosity 4 = 150 ml / G.

IR spectroscopic analysis gives 37.6 ffi 1.2; 23.5% cis 1.4; 38.9% trans 1.4; C comparative experiment: 4 ml of n-butyl lithium solution are added to 1.4 l of toluene 20 ml of triethylamine and 200 ml of butadiene are added and 20 hours at one temperature stirred from 20 - 40 ° C. After working up, a yield of almost 100% is obtained Polybutadiene obtained with the intrinsic viscosity g = 48 ml / G. IR spectroscopic structure analysis gives 43.2% 1.2 units, 22.7% cis 1.4 units, 34.1% trans 1.4 units.

Example 2 A Preparation of the catalyst To 20 l of toluene there are 40 ml of n-butyl lithium and 11.6 ml of dipropylamine and 15 minutes at 20 ° C below Stirring to exclude air and moisture. A solution of lithium dipropylamide is obtained.

B Polymerization To this solution, 100 ml of triethylamine and 5 1 butadiene given and stirred for 24 hours at room temperature. After the work-up a polybutadiene with the intrinsic viscosity = 380 ml per gram is obtained. It contains 30% 1.2 units, 30% cis 1.4 units and 40% trans 1.4 units.

Example 7; Example 1 is repeated, but instead of 20 ml of triethylamine 0.1 ml of N, N, N ', N'-tetramethylethylamine is added. After processing the The reaction mixture becomes a polybutadiene with an intrinsic viscosity of q = 134 ml / g obtained in almost 100% yield. IR spectroscopic analysis gives 57.7 96 1,2-units, 19.2% cis-1,4-units and 23.1% trans-1,4-units.

Example 4 A Preparation of the catalyst To 20 ml of tetrahydrofuran are given 1 g of naphthalene, 0.62 g of potassium and 2.2 ml of dipropylamine and while stirred until the potassium is completely implemented. It uses a complex of potassium dipropylamide and tetrahydrofuran.

B Polymerization 1.4 liters of benzene and 200 ml are added to this complex Given butadiene and stirred for 20 hours at 2o0C. The polybutadiene obtained has an intrinsic viscosity fz 180 ml / g. It contains 56 ffi 1.2; 12.2% cis 1.4; and 31.8 β trans 1.4; Units.

Example 5 A Preparation of the catalyst To 200 ml of toluene are added 2.5 g of cyclohexylamine and 12.5 ml of n-butyllithium are added and at 200 ° C. for 15 minutes touched. A solution of lithium dicyclohexylamide is obtained.

B Polymerization 20 ml of tetrahydrofuran, 1 Given liters of toluene and 200 ml of butadiene and 20 hours at a temperature of Stirred at 20 - 6o0C. The polybutadiene obtained - yield almost 100% - has the intrinsic viscosity t = 60 ml / G.

It contains 66% 1,2, 15.5% cis 1,4 and 18,5 trans 1,4 structural units.

Example 6 Example 5 is repeated, only instead of the tetrahydrofuran 20 ml of tri-n-butylamine are used. The polybutadiene obtained has an intrinsic viscosity t = 80 ml / G. It contains 21.5% 1.2; 36% cis 1.4; 42.5 ei trans 1.4 units.

Example 7 0.14 g of sodium dipropylamide and 20 ml of tetrahydrofuran added. A mixture of 200 ml of butadiene and 20 ml of styrene is made added at 200 ° C. and the polymerization batch was stirred for 20 hours. Is received a statistical copolymer of styrene and butadiene in almost 100 fingers the intrinsic viscosity 4- 120 ml / g. The product contains 16.4% styrene units, 39.4 X 1.2 butadiene units and 44.2% trans 1.4 butadiene units.

The experiment is repeated but the styrene is only added after the butadiene is polymerized. The result is a corresponding block copolymer.

Example 8 A Preparation of the catalyst To 100 ml of toluene are added 1.5 ml of dipropylamine and 5 ml of n-butyllithium and lo ml of tetrahydrofuran are added and stirred for 15 minutes. A tetrahydrofuran complex of potassium dipropylamide is obtained.

B Polymerization 1 liter of toluene and 200 ml Given isoprene and stirred for 20 hours.

The polyisoprene obtained in almost 100% yield contains 45 % 3; 4 isoprene units.

Example 9 A) Preparation of the catalyst: 4 ml of N-butyllithium solution and 1.38 ml of diisobutylamine are added to 1 l of N-hexane and the mixture for 15 minutes stirred at a temperature of 200 C with exclusion of air and moisture.

A solution of lithium diisobutylamide is obtained.

B) Polymerization: 0.12 ml of N, N, N ', N'-tetramethylethyldiamine are added to the solution according to A) and 400 ml of butadiene are added and the mixture is stirred at a temperature of 20 ° -400 ° C. for 20 hours.

After the reaction solution has been worked up, the yield is almost 100% obtained a polybutadiene with an intrinsic viscosity of 84-84 ml / g. IR spectroscopic Analysis gives 64.0 96 1.2 units, 17.3 96 cis 1.4 units and 18.8% trans 1.4 units.

Example 10 Example 9 is repeated, but instead of 0.12 ml 0.1 ml of dimethoxyethane is added to N, N, N ', N'-tetramethylethyldiamine.

After the reaction mixture has been worked up, a polybutadiene is used an intrinsic viscosity of! 7 = = 90 ml / g in almost 100% yield. IR spectroscopic Analysis gives 62.1% 1,2-units, 18.5% cis-1,4-units and 19.4% trans-1,4-units.

Example 11 A) Preparation of the catalyst: 20 ml of N-butyllithium solution and 5.5 ml of dipropylamine are added to 20 l of N-hexane and the mixture for 15 minutes stirred at a temperature of 20 ° C.

A solution of lithium dipropylamide is obtained.

B) Polymerization 5 ml of N, N, N ', N'-tetramethylethyl diamine are added to the mixture according to A) and 6 liters of butadiene are added and the mixture is stirred at a temperature of 20 ° -400 ° C. for 20 hours. After the reaction solution has been worked up, it becomes a polybutadiene with an intrinsic viscosity of t = 218 ml / g obtained in almost 100 of the above yield.

IR spectroscopic analysis gives 62% 1.2 units, 17.3% cis-1,4 units and 20.7% trans-1,4-units O

Claims (2)

Claim: »Process for homo- and copolymerization of conjugated Serve in inert organic solvents, characterized in that as Catalyst uses an alkali amide in the presence of a solvating agent for the amide. 2. The method according to claim 1, characterized in that at least one organic diene in an organic solvent with an alkali metal amide of the formula wherein R = C3 - C20 alkyl, C5 - C7 cycloalkyl, C6 - C10 aryl, R '= R, C1 - C20 alkyl, C5 - C7 cycloalkyl, C6 - C10 aryl and Me is lithium, sodium or potassium reacts in the presence of a solvating agent .