Polymerization of olefinic-containing monomers employing anionic

Details Polymerization of olefinic-containing monomers employing anionic Polymerization of olefinic-containing monomers employing anionic

1992-08-17

1994-07-19

Teskin, Fred

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

5253332, 525343, 525348, 5253591, 525360, 525367, 525383, 525379, 525385, 525386, 526173, 526178, 526335, 526348, C08F 842, C08F 834, C08F 832, C08F 446

Patent

active

053310586

DESCRIPTION:

BRIEF SUMMARY
This invention relates to a process for the polymerisation of olefinic-containing monomers employing anionic initiators. The invention also relates to novel anionic initiators for use in said process, and to polymers produced by said process.
Highly useful polymeric products can be obtained by polymerising olefinic-containing monomers in the presence of an organo-alkali metal initiator and subsequently reacting the resulting polymer, containing an active alkali metal end group or groups, with a reagent which will either couple the polymer molecules or replace the alkali metal with more stable reactive end groups.
It can be seen that such a polymerisation process will consist essentially of three stages:
a. Initiation, in which the monomeric material is contacted with a monofunctional or difunctional anionic initiator.
b. Propagation, in which the monomer is allowed to polymerise to form living polymer chains with negatively charged ends, and
c. Terminator, in which the living polymer chains are treated with suitable reagents, generally to form monofunctionally or difunctionally terminated polymers.
The presence of a reactive terminal group or groups on the ends of the polymer molecules enables substantially more effective cures to take place. In the case of a polymer containing a reactive group on each of its ends (a telechelic polymer) all of the polymer molecule will be tied into the cross-linked structure of the cured material.
The well defined structure produced by telechelic polymers in the networks of their cured products is the primary reason for their increased use as precursors in the commercial production of cured rubbery solids.
However, in order to meet the requirements of a modern synthetic rubber it is not enough that the polydiene produces effective cures nor that the cured product has a well defined cross linked structure, it is also important that the cured product possesses good elastomeric properties. In the case of polydienes the elastomeric quality of the cured product is dependent upon the 1,4-content of the polymeric diene. Generally, the higher the 1,4-content of the polymer, the lower its glass transition temperature and the better the elastomeric properties of the cured product. It follows from this that any process chosen for the commercial production of polydienes (in particular telechelic polymers of 1,3-dienes) must lead to a material having a high 1,4-content.
It is well known that monofunctional polyalkenes and high 1,4-content monofunctional polydienes can be prepared in inert non-polar hydrocarbon solvents by initiating the reaction with a monofunctional anionic initiator such as butyl lithium. The preparations of telechelic polydienes, using corresponding difunctional initiators such as 1,4-dilithiobutane, has hitherto required that the anionic polymerisation reaction (propagation) takes place in the presence of a sterically-hindered Lewis acid in order to ensure that the polymeric product possesses a reasonable 1,4-content (typically 25-50%). Furthermore, the polymerisation reaction must take place in polar solvents such as alkyl and cycloalkyl ethers because difunctional initiators are insoluble in non-polar solvents such as hydrocarbons, and this has hitherto prevented the formation of polydienes with 1,4-contents above about 50% which can be produced using the aforementioned monofunctional initiators in hydrocarbon solvents.
A further disadvantage associated with the use of difunctional initiators is that the choice of telechelic polymers which can be produced at the termination of propagation is restricted to those having identical terminal groups at either end since the reagent used for termination will react in a similar manner with both living ends of the growing polymer chain.
The main object of the present invention is to provide a new process for the anionic polymerisation of an olefinic-containing monomer which can be used to prepare telechelic polymers and yet avoids the disadvantages associated with the use of known difunctional initiators. It is a further o

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