IMPROVED POLYURETHANE PREPOLYMERS HAVING LITTLE OR NO PLASTICIZER AND THEIR USE IN VEHICULAR GLASS ADHESIVES

摘要

An isocyanate terminated prepolymer has been discovered that has sufficiently low glass transition temperature (Tg), necessary rheological properties and mechanical properties that allows for the making of adhesive compositions useful for bonding substrates into larger structures (e.g., windows in vehicles and buildings) with minimal or no plasticizers. The polyether prepolymer comprises a polyisocyanate reaction product of a polyisocyanate having an isocyanate functionality of greater than 2 and a polyether monol having an average molecular weight (Mw) of 1000 to 2000 g/moles and said prepolymer having: (i) a weight molecular weight average (Mw) of about 2000 to about 30,000 g/mole, (ii) a free isocyanate content of 0.8% to 4% by weight of said prepolymer, and (iii) viscosity of 1000 to 50,000 centipoises.

主权项

1. A method of forming an isocyanate terminated prepolymer comprising:
a. providing, a polyisocyanate having an average isocyanate functionality of greater than 2 to 2.7 b. reacting the polyisocyanate with a monol having an average molecular weight (Mw) of 1000 to 2,000 and a polyol to form the isocyanate prepolymer, the polyol and monol having an overall hydroxyl functionality that is from 1 to 3, and the polyol being comprised of
i. a diol having an average molecular weight (Mw) of 500 to 8,000 grams/mole andii. a triol having an average molecular weight (Mw) of 1500 to 4500 grams/mole, wherein, the monol is present in an amount from 40% to 60% of the hydroxyl groups in the polyol and monol, the diol is present in an amount from 5% to 35% of the hydroxyl groups present in the polyol and monol and the triol is present in an amount from 10% to 40% of the hydroxyl groups present in the polyol and monol and the isocyanate index is from 1.1 to 2.2.