Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-06-25
2002-12-17
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S335000, C526S347000
Reexamination Certificate
active
06495647
ABSTRACT:
BACKGROUND OF THE INVENTION
The carbocationic polymerization of olefins is well-known and has been studied in detail. These processes can be initiated by systems producing carbocations. These initiating systems include Lewis and Bronsted acids, organic compounds such as halides in conjunction with Lewis acids, etc. (J. P. Kennedy: Cationic Polymerization of Olefins: A Critical Inventory. Wiley-Intersci). These processes produce high or low molecular weight polymers with various halide or olefinic functional groups, and can be further functionalized by post-polymerization reactions.
The living carbocationic polymerization of olefins such as isobutylene and styrene is a relatively new development. Prior art describes living carbocationic polymerizations producing polymers with controlled molecular weights and molecular weight distributions as low as M
w
/M
n
=1.05 (see U.S. Pat. No. 5,169,914). Suitable initiators include compounds with tertiary functional groups of the general formula shown below:
where R
1
, R
2
and R
3
can be hydrogen or aliphatic or aromatic alkyl groups, or aralkyl groups, and X can be a halogen, hydroxyl, ether or ester groups, or peroxides. These initiators, in conjunction with Lewis acids, Electron Pair Donors and Proton Traps, have successfully been used to produce homopolymers and random or block copolymers. The prior art has recently been reviewed in detail (Rubber Chem. Techn. 69, 462 (1996). Multifunctional initiators carrying the above described tertiary functional groups have also been used to produce multiarm-star branched polymers (J. Polymer Sci., Chem. October 1997).
The above discussed living initiating systems produce halide-functionalized polymers, which can be further modified to yield other functional groups such as hydroxy- or ester. Unfortunately, these initiators are usually not available commercially and have to be synthesized by multistep synthetic routes.
SUMMARY OF THE INVENTION
The inventor has discovered that epoxides, when reacted with Lewis acids in the presence of olefins such as isobutylene and styrene, effectively initiate the carbocationic polymerization of those olefins. Epoxides are commercially available or can be synthesized by oxidizing olefins by a simple and fast process (e. g., reacting the olefin with m-Cl-perbenzoic acid in a polar solvent at room temperature, completing the reaction in a few minutes. P. Dreyfuss and J. P. Kennedy: Analytical Chem. 47(4), 771 (1975)). Epoxides are known to undergo polymerization themselves, by cationic, anionic or coordination mechanism, to yield polyethers containing oxygen in the main chain. Epoxi-ethane undergoes living anionic polymerization yielding a polyether, but substituted epoxides suffer side reactions. (Encyclopaedia of Polymer Science and Engineering, 2
nd
Ed., Mark, Bikales, Overberger, Menges Eds., 14, 634, John Wiley&Sons, 1985). In the present invention, epoxides, preferably substituted epoxides, initiate the living polymerization of olefins yielding hydrocarbon polymers, instead of undergoing self-polymerization. Thus the epoxide initiating systems of the present invention produce hydrocarbon polymers with hydroxy functionality; multifunctional epoxides will produce multiple hydroxy functionalities. There is no prior art for using epoxides as initiators for the cationic polymerization of olefins.
Thus according to one aspect of the invention, there is provided a carbocationic polymerization process for producing a polyolefin polymer or copolymer carrying oxygen-containing functional group(s) (e.g., hydroxy or aldehyde) group(s), which comprises introducing a monomer charge, a Lewis acid as coinitiator and an organic epoxide compound as initiator into a suitable reaction vessel and polymerizing the monomer charge at a temperature of from about 0 degrees to about −120 degrees centigrade to form the terminally functional polymer. The monomer charge comprises the concurrent and/or sequential addition of isobutylene and a second monomer selected from the group consisting of conjugated diolefins and vinylidene aromatic compounds, and the epoxide initiator is charged in an amount of from 10
−6
to about 10
−1
moles per mole of the isobutylene.
According to another aspect of the invention, there is provided a living carbocationic polymerization process for producing a polyolefin polymer or copolymer carrying oxygen containing functional groups (e.g., hydroxy or aldehyde group(s)), which comprises introducing a monomer charge, a Lewis acid as coinitiator and an organic epoxide compound as initiator, a proton trap to prevent protic initiation, and an electron pair donor which may or may not be necessary to achieve living conditions, into a suitable reaction vessel and polymerizing the monomer charge at a temperature of from about 0 degrees to about −120 degrees centigrade to form the terminally functional polymer. The monomer charge comprises the concurrent and/or sequential addition of isobutylene and a second monomer selected from the group consisting of conjugated diolefins and vinylidene aromatic compounds and the epoxide initiator is charged in an amount of from 10
−6
to about 10
−1
moles per mole of the isobutylene.
Another view of the invention is that it provides a new class of initiators for inducing the cationic polymerization of olefins. These initiators, in conjunction with Lewis acids as coinitiators, effectively initiate the carbocationic polymerization of olefins. The new initiators are epoxides with the general formula
where R
1
, R
2
and R
3
are hydrogen, alkyl, aryl or aralkyl groups, and can be the same or different, and i is a positive whole number. The Lewis acid has the general formula of MtX
n
where M is titanium, aluminum, boron or tin, X is a halogen, an alkyl or an alcoxy or a mixture thereof. The process is a carbocationic process, which can be living or non-living, at a temperature of from about 0 to −80 C. The polymer produced can be a homo- or copolymer (random or block) carrying hydroxy functional groups.
Further aspects of the invention and additional details and examples will be provided or will become apparent in the detailed description which follows.
DETAILED DESCRIPTION
Tertiary carbocations that are formed by the interaction of an initiator carrying a tertiary functional group, and a Lewis acid such as BCl
3
or TiCl
4
, were shown to be effective initiators for the carbocationic polymerization of olefins. Such an initiator is 2,4,4-trimethylpentyl chloride in conjunction with TiCl
4
. In her search for commercially available initiators the inventor has theorized that substituted epoxides may be effective initiators for living carbocationic polymerizations. It is taught that epoxides may undergo cleavage under acidic or basic conditions, and the cleavage is oriented in substituted epoxides: (Morrison&Boyd: Organic Chemistry, 6
th
Ed., 483 Prentice Hall, 1992)
Epoxides are also known to polymerize to form polyethers. This polymerization reaction forms the base of commodity bonding compounds such as epoxy resins. The challenge was to find conditions under which tertiary carbocations forming from a substituted epoxide in conjunction with a Lewis acid would initiate the carbocationic polymerization of olefins instead of undergoing self-polymerization.
The inventor has found that compounds such as 2,4,4-trimethylpentyl-1,2-epoxide, as 2,4,4-trimethylpentyl-2,3-epoxide, alpha-methylstyrene epoxide and squalene epoxide in conjunction with a Lewis acid such as TiCl
4
are effective initiators for the polymerization of olefins such as isobutylene.
Without wishing to be bound by the theory, initiation is proposed to take place by the following sequence of reactions:
The carbocation initiates the polymerization of the olefin, or may undergo competitive self-polymerization. This latter side reaction may decrease the initiator efficiency, but the side product was found not to influence the living nature of the polymerization. Since opening the epoxi ring requires at least one TiCl
4
pe
Armstrong R. Craig
Borden Ladner Gervais LLP
Harlan R.
Marsman Kathleen E.
The University of Western Ontario
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