Preparation of vinylether and alpha-methylvinylether polymers
Publication Date: 2010-Aug-30
The IP.com Prior Art Database
The present invention relates to the preparation of vinylether and alpha-methylvinylether homo- and copolymers by (co)polymerizing a vinylether or an alpha-methylvinylether, op-tionally with at least one ethylenically unsaturated monomer different therefrom, in the presence of SnCl4 and ethylaluminiumdichloride and also in the presence of a carbox-ylic acid adduct of at least one vinylether or alpha-methylvinylether as an initiator.
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 SnCl4 and ethylaluminiumdichloride and also in the presence of a carbox- ylic acid adduct of at least one vinylether or -methylvinylether as an initiator.
(-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 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 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- 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, which has to be produced in a separate step, but must a...