Aqueous polyurethane dispersions and adhesives based thereon
AssigneeH.B. Fuller Licensing & Financing, Inc.
InventorsThomas E. Rolando, Peter A. Voss, Christopher M. Ryan
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Abstract
Aqueous polyurethane dispersions used in adhesives for manufacturing laminate structures are provided with improved dispersion properties, which provide improved shelf-life stability of the dispersion and greater transparency and handling characteristics in application machinery for adhesives formulated therefrom, when a tertiary amine is present during an initial polyurethane prepolymer reaction between an isocyanate and a polyol component having acid functional groups. The initial reaction is carried out prior to formation of the dispersion in water.
Claims16
An improved method for producing an aqueous dispersion of a polyurethane polymer, the method including the steps of:
- (i) reacting a mixture of (a) an aliphatic polyfunctional hindered isocyanate compound, and (b) an acid functional polyol component to form a polyurethane prepolymer, the polyol component comprising a polyol having at least two isocyanate reactive hydrogens and at least one acid functional group or a combination of a polyol free of acid functionality having at least two isocyanate reactive hydrogens and a compound having acid functionality and hydroxy, amine or thiol functionality;
- and then
- (ii) dispersing the resulting polyurethane prepolymer in water in the presence of a dispersion stabilizing amount of a tertiary amine,
- the improvement wherein the prepolymer has an acid number of between 10 and 22, the dispersion is free of volatile organic solvents and the tertiary amine is added to the prepolymer forming reaction mixture of isocyanate compound and the polyol component prior to said prepolymer forming reaction.
Dependencies are inferred from the claim text.