Ultra low voc polyurethane coatings
AssigneeAir Products and Chemicals, Inc.
InventorSherri Lynn Bassner
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Abstract
This invention relates to improved two part, low VOC polyurethane coatings comprising a low viscosity polyisocyanate component having an isocyanate functionality greater than two and a polyol component having a functionality equal to or greater than two. The improvement resides in the utilization of a unique isocyanate component in the two part polyurethane coating formulation. The isocyanate component comprises said low viscosity polyisocyanate component and an isocyanate terminated or end capped prepolymer formed by the reaction of a diisocyanate and a multifunctional polyol, the prepolymer having at least about 85 preferably 90 percent by weight of a 2:1 adduct of isocyanate to polyol (NCO/OH) and less than about 1 and preferably less than about 0.5% by weight of residual diisocyanate monomer therein.
Claims7
An isocyanate mixture suited for producing polyurethane coatings which comprises:
- (a) from about 10 to 90 weight parts of a prepolymer comprising the reaction product of a diisocyanate component and a long chain polyol component having an average hydroxyl functionality greater than 2.0, said prepolymer having an equivalent weight from about 250 to 2000 grams per equivalent, an unreacted diisocyanate monomer content of less than about 1% by weight, and a molar concentration of oligomers of less than 15%;
- and,
- (b) from about 10 to 90 weight parts of a polyisocyanate crosslinker selected from the group consisting of an adduct of an aliphatic or aromatic diisocyanate and an aliphatic polyol, an isocyanurate of an aliphatic or aromatic diisocyanate, a biuret of an aliphatic or aromatic diisocyanate, a uretdione of an aliphatic or aromatic diisocyanate, an allophanate of an aliphatic or aromatic diisocyanate or mixture of the same, the isocyanate mixture totaling 100 weight parts.
Dependencies are inferred from the claim text.