Aqueous dispersions of acidic ethylene interpolymers

Abstract

Aqueous dispersions useful in adhesive and coating applications, and a method of preparing the same. The dispersion contains (a) an ethylene interpolymer having an acid number of at least 117, a melt flow of at least 50, and comprising from 15 to 24 percent by weight of the interpolymer of interpolymerized ethylenically unsaturated carboxylic acid, such as acrylic or methacrylic acid, (b) from about 5 to about 2,000 parts by weight per 100 parts of the interpolymer of a rosin tackifier having an acid number of at least about 76 and being compatible and codispersible with the interpolymer, (c) water in an amount sufficient to provide a solids content of the dispersion of from about 10 to about 60 percent, and (d) water soluble alkali in an amount effective to neutralize from 20 to 130 percent of the acid groups in the interpolymer and the tackifier, to disperse at least 99 percent by weight of the interpolymer and the tackifier, and to provide a viscosity of the dispersion which is less than about 1,500 Pa-s. The dispersion is prepared by heating and agitating a mixture of the ingredients sufficiently to disperse at least about 99 weight percent of the interpolymer and the tackifier.