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AssigneeThe Dow Chemical Company
InventorsMichael E. Rowland, Kenneth E. Springs
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Aqueous dispersions of ethylene/.alpha.,.beta.-unsaturated carboxylic acid interpolymers (e.g., random ethylene/acrylic acid interpolymers) are formed using a mixture of bases at a concentration of at least about 0.2 equivalents of base per mole of .alpha.,.beta.-unsaturated carboxylic acid. The dispersions have at least about 10 weight percent dispersed solids and not more than about 1 weight percent of the initial polymer in non-dispersed form. Preferred bases for use in forming the dispersions are ammonium hydroxide and/or alkali metal hydroxides. A mixture of ammonium hydroxide and potassium hydroxide is especially preferred for forming the dispersions with ethylene/acrylic acid interpolymers at an ammonium hydroxide:acrylic acid molar ratio of about 1:1 and a potassium hydroxide:acrylic acid molar ratio in the range of about 0.6-0.8:1. The dispersions are particularly useful in forming thin coatings of adhesive on substrates, such as paper and metal foil, using conventional techniques.
In a method of forming an aqueous dispersion of at least one ethylene/.alpha.,.beta.-unsaturated carboxylic acid interpolymer comprising contacting the interpolymer(s) in a stirred aqueous medium with a mixture of bases, the improvement characterized by contacting the interpolymer with at least about 0.2 equivalents of base per mole of .alpha.,.beta.-unsaturated carboxylic acid, said base being a mixture of monoethanolamine, diethanolamine or ammonium hydroxide and at least one alkali metal hydroxide in a ratio of from about 1.5 to about 3 moles of ammonium hydroxide per mole of alkali metal hydroxide, thereby forming a dispersion having at least about 10 weight percent of dispersed solids, total weight basis at not more than about 1 weight percent of non-dispersibles, based on the weight of the interpolymer.
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