Tuesday, July 6, 2010

Polyvinyl Alkyl Ethers

Polyvinyl alkyl ethers (some of which are elastomers although not generally classified as synthetic rubbers) are further examples of vinyl polymers having valuable adhesive properties. The monomers are prepared from acetylene and an alcohol in the presence of an alkali alcoholate. Polyvinyl ethyl ether, polyvinyl n-buthyl ether and polyvinyl isobutyl ether all range from extremely tacky semi solid to elastomeric solids, and therefore polymer blends can be made having properties that are appropriate to a wide range of adhesive applications. Polyvinyl methyl ether is a highly viscose liquid or a semi solid. The largest use of the polyvinyl ethers is in pressure sensitive adhesives. Polyvinyl stearyl ether is a waxy solid that is sometimes used as a modifier in adhesive compositions.

The rubbery types of polymer are soluble in a range of organic solvents which includes ketones, ethers, hydrocarbons and the lower alcohols and derived esters. In solution form they are one of the large variety of adhesive used for sticking shoe soles, and for other applications where immediate high tack (“quick grab”) is important. They have limited heat resistance but remain non-brittle at temperatures well below zero centigrade.

Copolymers of vinyl ethers have been prepared; of interest as adhesives are emulsion copolymers with acrylic esters or vinyl chloride, and copolymers of lower alkyl vinyl ethers with acrylic esters. Vinyl methyl ether and maleic anhydride form water soluble copolymers that are used as adhesives by themselves and as thickeners in aqueous solution of other adhesives.