Preparation of vinylether and alpha-methylvinylether polymers
Publication Date: 2010-Aug-30
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The present invention relates to the preparation of vinylether and alpha-methylvinylether homo- and copolymers by (co)polymerizing a vinylether or an alpha-methylvinylether, optionally with at least one ethylenically unsaturated monomer different therefrom in the presence of at least one oxophile Lewis acid and at least one alcohol selected from C1- C6-alkanols and polyols, where the molar ratio of the at least one alcohol to the(co)monomers to be polymerized is from 1:20 to 1:1000.
Preparation of vinylether and -methylvinylether polymers
The present invention relates to the preparation of vinylether and -methylvinylether
homo- and copolymers by (co)polymerizing a vinylether or an -methylvinylether, op- tionally with at least one ethylenically unsaturated monomer different therefrom in the presence of at least one oxophile Lewis acid and at least one alcohol selected from C1-
C6-alkanols and polyols, where the molar ratio of the at least one alcohol to the
(co)monomers to be polymerized is from 1:20 to 1:1000.
(-Methyl)Vinylether polymers are versatile products which find a wide range of appli- cations, for example for pressure-sensitive and other adhesives, waterproofing applica- tions, construction materials and coatings, compatibilizers and modifiers for thermo- plastic blends, sizing agents for papers, emulsifiers and demulsifiers.
They are generally prepared by cationic or radical polymerization. The cationic polym- erization is generally carried out with a Lewis acid. The cationic polymerization can also be carried out as a living cationic polymerization. Living cationic polymerization refers generally to the polymerization of isoolefins, vinylaromatics or other suitable ethyleni-
cally unsaturated compounds in the presence of metal or semimetal halides as Lewis acid catalysts and tert-alkyl halides, benzyl or allyl halides, benzyl or allyl esters or benzyl or allyl ethers as initiators which form a carbocation or a cationogenic complex with the Lewis acid. A comprehensive review on this subject can be found in Ken- nedy/Ivan "Carbocationic Macromolecular Engineering", Hauser Publishers 1992.
In case of vinylethers, living cationic polymerization, where the Lewis acid forms a car- bocation or a cationogenic complex with an initiator molecule, are often performed by using the HCl-adduct of a (-methyl)vinylether as the initiator. This initiator type how- ever has the disadvantage of being toxic and also highly reactive. A too high reactivity
or gradient copolymer.
JP 06-322049 describes the preparation of vinylether/styrene blockcopolymers by add- ing at -78 °C a vinylether monomer, SnCl4 and a tetrabutylammonium salt to the HCl-
of the initiator disadvantageously may result in polymers with a broad molecular weight distribution. In case of the preparation of block copolymers, high initiator reactivity may require a multistage process, where the comonomers have to be introduced sequen- tially in order to avoid that polymerization takes place more or less simultaneously for all comonomers independently of their inherent reactivity and thus results in a statistic
adduct of isobutylvinylether. After completion of the polymerization of the vinylether monomer styrene is added and the reaction temperature is raised to -15 °C. In this process, the production of blockcopolymers not only requires the use of the toxic HCl- adduct of isobutylvinylether...