DE2215865A1 - Process for the preparation of a diene block copolymer - Google Patents

Description

SHELL HTTERITATIOHALE RESEARCH MAATSCHAPPIJ letter V Carel van Bylandtlaan 30, The Hague, Netherlands

concerning

Process for the preparation of a diene bloak copolymer

The invention relates to a process for the preparation of a block copolymer, wherein a conjugated Diene in the presence of an organic lithium compound is polymerized as an initiator.

The preparation of block copolymers by sequentially polymerizing a monoalkenyl aromatic hydrocarbon and a conjugated diene hydrocarbon using a lithium lithium organism Connection as initiator is known. In this type of block polymerization, a roonoalkenyl-substituted one is first used aromatic hydrocarbon in the presence of an organic monolith as initiator polymerized until a non-elastomeric living polymer block with a terminal lithium atom is formed; thereon v / the conjugated diene hydrocarbon is added and polymerized to form an elastomeric polymer block; a monoalkenyl-substituted hydrocarbon then becomes again added and to a second non-elasto- + aromatic ~ 2 -

209843 / 10U

U-41 044

polymer block polymerized. The resulting product is isolated by coagulation or precipitation. It is also known to produce block copolyraers by initially a monoalkenyl-substituted aromatic hydrocarbon in the presence of an organic monolith Polymerized compound as initiator and then adding a conjugated diene hydrocarbon, with a living 2-polymer block with terminal lithium atom is created, whereupon using the living polymer chains a coupling agent are added together, which is either a dihaloethane or a carboxylic acid ester, depending depending on whether a linear or multi-branched structure is desired ..

The hydrocarbon block copolymers of this type are usually thermoplastic and can be elastomers, depending on the chemical nature of the various Blocks, the individual block molecular weights, the ratio of the different types of blocks to each other and the total molecular weight .

In this anionic block copolymerization, the prior art teaches that diene molecules in the growing polydienyllithium chain can occur in different ways with the formation of 1,4-cis and 1,4-trans as well as 1,2 (vinyl) - microstructures. Isoprene and other substituted diene molecules occur in both 3,4 and 1,4 configuration Configuration, but the percentage in the 1,2 configuration is generally very low. The unsaturated bonds in polymers can thus be present either in the main chain or in short vinyl or isopropenyl side chains. When a conjugated diene is polymerized in an inert hydrocarbon solvent, a polymer block is formed with a low content of the 1,2-configuration but a high total content of the 1,4-configuration.

2098A3 / 10U ~ ⁵ ~

1A-41 044 - 3 -

Is a polar substance, "for example an ether or if a tertiary aliphatic atnin is present, then the polymerized monomeric diene molecules to form a 1,2 microstructure, the extent of which depends on the amount the added polar substance. By choosing appropriate conditions and the correct diene monomer, Polymer blocks with up to 85 to 90 percent 1,2 or 3,4 microstructure or manufacture with up to 90 to 92 percent 1,4 configuration. The different microstructures are verified by IR analysis or by HIiR spectrometry.

The physical properties of diene polymer blocks depend to a considerable extent on the number of small side chains which are attached to the main polymer chain are bound. Methyl side chains are usually formed by methyl groups that were originally used in the Diene are present, for example in the polymerization of isoprene. Elastomeric property, rebound resilience, Tensile strength, glass transition temperature, crystallizability, and other properties imparted by any polymer block depend very much on the number of small side chains on the main chain. Therefore must in order to achieve the desired product properties, the polymerization conditions during the formation of diene Earth blocks strictly controlled.

The invention now provides a process for the preparation of a block copolyraeren in the presence of an organic lithium Compound as an initiator, which is characterized in that one

a at least one conjugated diene in the presence of a Ether, thioether, tertiary anine or hexaalkylphosphoramine as a modification agent for the microstructure to a diene polymer block with more than 25 # 1,2- or

- 4 ~ 2 0 0 0 A 3/1 0 1 4

U-41

3,4- configuration polymerized,

b thereon at least one dihydrocarbyl compound of zinc,

CadoiuB, magnesium, caIoium, strontium, or barium all complex-forming agents are added and

ο the same or a different conjugated diene or a Mixture of conjugated bees adds and to a second block with less 1,2 or 3,4 configuration than polymerized in the first blook.

They unsaturated block copolymers according to the invention can correspond to one of the following general formulas:

AB, ABA, BAB, A ~ fB-A) _2-5 , B- ^ AB) _2-5 , AB- (BA) _2-5 or BA ^ AB) _2-5

Each A and B are polymer blocks from the same conjugated diene or from different conjugated dienes; the polymerization conditions are adjusted so that the Polyr A oerblöoke a low content of 1,2- or 3,4-configuration and the Polymerblöoke B a medium to high content (more than 25 i>) of 1,2- or 3,4 - own configuration; the rest in either blook A or B has 1,4 configuration.

The 1,2-microstructure or configuration closes the 3,4- microstructure or configuration in the present Description and the claims, because usually both types of configuration have the same effect on the physical properties of the polymers and the Methods '' for making these configurations or structures are the same.

The blocks A and B can be polymerized from the same diene

209843/1014 - 5 -

1A-41 044

, resulting in a heteroblock homopolymer that is a polymer which consists exclusively of the same monoroerene units, however, it is made up of blocks of different structures. The blocks can also be made from different or diene mixtures be polymerized, in which case a block copolymer is present. In the present description and claims, block copolymers are used to describe both types of block polymers Understood.

Are in · any point in the above general Formulas two identical blocks A or B directly connected to one another, with an optionally present remainder of the Coupling agent remains unconsidered, so they are grounded interconnected blocks are considered as a single block. Branched structures or linear configurations can be produced by. Coupling of living 2-block copolymers or sequential polymerization. For example, if a tetrafunctional coupling agent such as If silicon tetrachloride is used, the corresponding Structure of the polymer can be represented by

B ■

B-A-rA-B

A.
I.
B.

In the latter case, any remainder of a coupling agent has been disregarded since it is an insignificant one Part of this formula for high molecular weight polymers is

In the production of diene polymer blocks under Use of lithium-organic compounds as initiators is the extent of the 1,2- or 5,4-microstructure pymonyait the number of side chains in the polymer block. The number of side chains controls the physical properties

209843 nG14 _ »β»

1A-41 044

each block. If there are more side chains, then there is a "certain polyra segment or polymer section in one The diene block is not as free in its mobility as it would be with fewer side chains of the pail; this as a result, certain section is less elastomeric and freezes faster when the polymer is cooled; i.e. its glass transition temperature is higher and its rebound elasticity (rubbery texture) Room temperature is lower.

. The average molecular weights of the polymer block A can be 3,000 to 50,000; the preferred range is 7,000 to 30,000. The Polyraerblocks B have a average molecular weight from 20,000 to 200,000; a range from 35,000 to 100,000 is preferred The proportion of polymer blocks A can range from 5 to 80 dollars Make up the total weight of the block copolymer.

For the preparation of the polymers according to the invention those conjugated diene monomers come into question, which 4 to 8 Contain carbon atoms in the molecule. Examples are butadiene, alkyl-substituted butadienes v / ie isoprene, 2,3-dimethylbutadiene and piperylene. Butadiene and isoprene are particularly preferred. These diene monoras can Contain small amounts of monovinyl substituted aromatic hydrocarbons or other copolymerizable monomers. Mixtures of dienes are contemplated to produce certain properties.

As a polymerization process, solution polymerization is preferred to the use of organic lithium compounds as a catalyst, for example lithium alkyls. The diene monomer is dissolved in a ? ~ Tri «a solvent, for example in an alkane, alkene, cyoloalkane, cyoloalkene or in an aromatic solvent or in a

209843M014 - 7 -

U-41 044 - 7 -

Mixture of these substances. Examples of solvents are Butene, butane, pentane, oyclopenten / cyclopentane, benzene, Toluene and xylene.

ν Anaerobic conditions are essential for the performance the polymerization and reactive impurities or Accompanying substances must be removed, both from the highly refined Monomers as well as solvents, in a manner known per se. Gate of adding the monomer to the solvent becomes one for polymerization to a polymer block of

• Corresponding molecular weight, sufficient amount of an organic lithium compound such as sec-butyllithium and an amount of a polar compound or a modifier, for. Micro structure such as tetrahydrofuran or tetradiamm, ^J

methylethylene / which is believed to be associated with the Lithium ion forms a complex, added to the reaction vessel. The monomer is then added and turned into one Polymer block with a moderate to high content of 1,2-configuration polymerizes, depending on the amount of polar present Substance. A second complexing agent such as zinc digethyl is then added. The polar substance doesn't need to be separated by distillation or in some other way, because their effect becomes zero by the reaction with the second complexing agent. Is the next diene monomer added or the polymerization with the same Continued monomers, the next polyra block formed contains little 1,2-configuration, because the other Multiplication of the active polydienyllithium system now like in a hydrocarbon solution proceeds with formation of predominantly 1,4-cis and 1,4-trans structure. The addition the complexing agent around the effect of polar substances on the microstructure created during the polymerization repeal is the essence of the new method according to the invention.

- 8 209843/1014

1A-41

The 2-block polymer is still active at this point because it has a terminal lithium atom, so if it is not is isolated as such, using known coupling agents such as dihaloethane or certain 'carboxylic acid esters or silicon tetrachloride can be coupled. The polymerization of the 2-block polymer can also continue with the addition of another diene monomer. If necessary, additional amounts of polar substances can be added before a third block is formed. The amount of polar substance then present exceeds the amount with which the second complexing agent can react and the newly added monomer is therefore polymerized again forming a block with a 1,2 configuration. According to a preferred mode of operation, if only one is used Diens the total amount of diene and all of the initiator required are added at the beginning of the polymerization in order to achieve all Obtain polymer blocks. The change from one configuration to the other in the different polymer blocks is then accomplished by adding the two types of complexing agents as required.

The process described can be carried out with a living polymer which already has one or more diene polymer blocks contains. A polymer block of a conjugated diene with little 1,2 or 3,4 configuration (and much 1,4 configuration) can be prepared first in an inert hydrocarbon solvent; then becomes a polar one Substance added before a polymer block of a conjugated diene with a moderate to high content of 1,2- or 3,4-configuration is produced; then the second complexing agent is added before the third polymer bloom is formed. The living blocks generated in this way are polypolynous can be inactivated and isolated or coupled in a manner known per se.

2 0 9 843/1014 ~ ⁹ "

1A-41 044 9 -

Polar substances or modifiers for the microstructure, which to complex with the lithium ion of the growing polydienyllithium system are suitable to directly incorporate monomers in the 1,2-configuration Ethers such as diethyl ether or tetrahydrofuran or dimethoxyethane, or thioethers such as dimethyl sulfide, tertiary aliphatic Amines such as triethylarain or, in particular, tetramethylethylenediamine or alkyl phosphoramides such as hexamethyl phosphoramide. The amount of polar substance required ranges from 0.5 moles to 50 moles of polar substance per MoILithiuraalkyl depending on the desired percentage of 1,2-configuration in the diene polymer block and the effectiveness of the polar substance. Even small amounts of polar substance increase the 1,2-configuration content above $ 15-20 compared to only $ 5-10 1,2-configuration, which are formed in the absence of polar substance.

Suitable second complexing agents which react with the abovementioned polar substances to form complexes, ■ so that the diene monomer is no longer directed in the 1,2-configuration when incorporated into the growing chain are dihydrocarbyl compounds of elements of group II of the periodic table, for example dialkyl, diaryl ^, dialkaryl and diaralkyl compounds of zinc, cadmium, magnesium, calcium, strontium and barium. Examples of preferred classes of compounds are diyalkyl zinc and dialkyl magnesium compounds such as diethyl zinc, dimethyl magnesium, dibuty magnesium and dimethylcadmium. In general, these second are complex-forming Agent required in amounts of 0.5 to 20 moles per mole of previously added polar substance. The preferred one Range is 1 to 4 moles of second complexing agent per mole of polar substance. The amount of the second to be added Coraplex-forming agent can optionally be chosen v / ground that a small amount of the polar compound present will not be complexed; in these cases

- 10 209843/1014

1A-41 044 - 10 -

stands in the subsequent polymerization up to 20 $ 1,2-configuration. Also, some of the second complexing agents do not form a very "tight" complex with the polar one Connection, so even in this case up to 20 $ 1.2 configuration during the subsequent polymerization »are formed.

The polymerization is carried out under conditions familiar to the person skilled in the art for the polymerization of dienes in the presence of lithium alkyl. Generally, temperatures of a particular block to produce the copolymer be applied of from 20 to 7O ⁰ C for a period of 0.1 to 5 hours. The reactions are carried out in a closed pressure vessel under autogenous pressure of the diene monomer and / or the solvent. The polymeric product is isolated by coagulating with hot water with stirring or by precipitation with a nonsolvent.

A preferred 3-block copolymer can be made in which the close blocks little 1,2-configuration and the middle block moderately much 1,2-configuration having. For this purpose, for example, the initial polymerization of the diene is carried out in the absence of a structure modifier, whereby a first block with little 1,2-configuration arises; thereupon becomes a modifier for the structure introduced and the polymerization continued, a second block with a higher content of 1,2-configuration being formed; Finally, the complexing agent is added and the polymerization takes place with the formation of a third block low content of 1/2 configuration.

The polymers according to the invention can be mixed with oils, Fillers, antioxidants, stabilizers and other common additives for rubber and plastics been mixed. These additives are often found in commercial products for a variety of purposes, particularly ^ un_

209843/1014

- 11 -
reduce their costs.

The vulcanizing agents present in commercial rubbers are useful in improving the properties of the unsaturated conjugated diene block copolymers of the invention. While useful for some applications requiring elastomeric properties, these precursor polymers have fairly poor strength and resistance to deformation; they must therefore be crosslinked in order to achieve the high strength which is necessary for commercial use in numerous fields.

The products according to the invention are suitable after Vulcanizing for most purposes for which rubbers are also used, for example for coatings, coatings, Films, mechanical products, latices, paints, heat-molded. Products and insulation material and can be processed in the usual way for rubbers. They can be compounded with or without the addition of conventional elastomers using rubber mixture components and extruded thereon or molded by pressing, injection molding or blow molding. The crowds can also be poured from solvents. The products obtained in this way can be processed in a customary manner vulcanize.

The following examples serve to explain the invention in more detail. Unless otherwise stated below Parts are to be understood as parts by weight.

example 1

This example illustrates the sequential preparation of a "heteroblock homopolyraeren" as described above and falling under the term block copolymer used here, composed of butadiene only. The terminal blocks of the product included 8 ° $ 1,2- configuration and the interior

209843/1014 ₁₂ ,

1A-41 044

- 12 -

blocks 28 $ 1.2 configuration. The remaining configuration in each block was 1,4-cis or 1,4-trans configuration. That 2 - block copolymer was coupled with phenyl benzoate.

In a solution of 1.0 mol of butadiene in cyclohexane, the polymerization was initiated with 0.54 mmol of sec-butyllithium _/ complexed with 0.54 mmol of tetramethylene / ethylenediamine. After 24 minutes of reaction at 25 to 30 ^° C., sample I of the polymer was removed; this sample had an average molecular weight of 27,000 and contained the 82 $ 1,2 configuration as determined by NMR analysis. The yellow solution was titrated with zinc diethyl until it turned colorless; this required 0.63 mmol of zinc diethyl or 1.26 mol per mole of tetramethylethylenediamine. The temperature was increased to 50 ^° C. and the polymerization was continued for 175 minutes in order to consume the butadiene present. Sample II was then taken. The 2-block copolymer had an average molecular weight of 86 and contained 45 $ 1 »2 configuration. The difference between sample I and sample II showed that the content of 1,2-configuration in the polymer block, which had been formed after addition of zinc diethyl, was $ 28.

Phenyl benzoate was added in an existing anionic chain ends equivalent amount (0.2 railliequins) at 25 ⁰ C. The temperature was increased ^{to 50 to 73 °} C. in the course of 70 minutes. The coupled block copolymer - Sample III - now had an average molecular weight of 140,000; the coupling efficiency was $ 90 as determined * by gel permeation chromatography.

Example 2

2-block and 3-block polymers were produced, their Similar blocks with a 1 »2 configuration and their internal Blocks from another diene moderately high to high 1,2 configuration had * ^ ?,

209843/1014

11-41 - 13 -

In a manner known per se, a cyclohexane solution of 1.0 mol of butadiene was initiated with 2.16 mmol of sec-butyllithium and then polymerized to an average molecular weight of 25,000. The 1,2-configuration content of this polymer was $ 8. Then 1.1 mmol of tetraraethylethylenediamine were added in order to react with the formation of a complex with the polybutadienyllithium; In addition, pre-titrated monomeric isoprene was added and the polymerization was continued until an isoprene polymer block with an average molecular weight of 100,000 and a 3,4-configuration content of 50 ° was formed. At this point the isoprene was essentially consumed.

The active 2-block polymer solution was divided into two parts. One part was coupled with phenyl benzoate, a 3-block copolymer containing a Q $> 1,2 configuration in the outer blocks. Sufficient zinc diethyl was added to the second part of the active 2-block copolymer to react with the tetra-methylethylenediarain (ie 1.25 moles per mole of diamine); then sufficient additional pre-titrated butadiene was added to produce a third polymer block of 25,000 average molecular weight. This last polybutadiene block contained little 1,2-configuration because the influence of tetramethylethylenediamine on the microstructure was destroyed by the firm complex bond of this compound with zinc diethyl.

The coupled polymer and the 3-block polymer were each mixed with 50 parts per 100 parts of carbon black HAI milled ^1, UOBS accelerators and sulfur, and vulcanized by heating in a vulcanizing press at 145 ⁰ C. These products are pesky, high-strength rubbers.

... 14 -

209843 / 10U

1A-41 044 - 14 -

Of course, the method just described can also be used when the polymerization initiator has a punctiformity> 1, such as, for example Dilithium stilbene.

Patent claims

209843/1014

Claims (2)

Claims Process for the preparation of a diene block copolymer by polymerizing conjugated dienes in the presence a lithiura-organic compound as an initiator, characterized in that one a at least one conjugated 'diene in the presence of one Ether, thioether, tertiary amine or hexaalkylphosphoramide as a modifier for the microstructure to a diene polymer block with more polymerized as 257 ° 1f2- or 3,4- configuration, thereon at least one dihydrocarbyl compound of zinc, cadmium, magnesium, calcium, or strontium Barium adds as a complexing agent and ■ with the same or a different conjugated diene or a mixture of conjugated diene further polymerizes to a second polymer block which has less 1,2- or 3,4-configuration contains as the first polymer block. 2. net uses. Method according to claim 1, characterized by g e.kennzeich-, that the conjugated diene is butadiene or isoprene 3. Method according to claim 1 or 2, characterized in that that one 0.5 to 50 moles of modifier for the microstructure per mole of lithium-organic compound used. 209843/1014 1Δ-41 044 Century 4. The method according to claim 1 to 3, characterized in that that one 0.5 to 20 moles, preferably 1 "to 4 moles of complex Mldendea agent per mole of modifier for the microstructure used 209843/1014