초록 ▼

Polyurethane prepolymers in which polyhydric alcohols are initially reacted with the faster reacting isocyanate group of an asymmetrical diisocyanate with the slowly reacting group remaining intact, after which the reaction products are combined with a symmetrical diisocyanate of which the equally r

Polyurethane prepolymers in which polyhydric alcohols are initially reacted with the faster reacting isocyanate group of an asymmetrical diisocyanate with the slowly reacting group remaining intact, after which the reaction products are combined with a symmetrical diisocyanate of which the equally reactive isocyanate groups again react more quickly than the slowly reacting groups of the first polyfunctional isocyanate compound. The products obtained by this process are distinguished by a low residual monomer content.

대표청구항 ▼

An isocyanate terminated polyurethane prepolymer having a low content of free isocyanate residual monomers which is the reaction product of (A) a low viscosity first stage prepolymer having free NCO moieties and free OH moieties which is itself the reaction product of (a) a first diisocyanate contai

An isocyanate terminated polyurethane prepolymer having a low content of free isocyanate residual monomers which is the reaction product of (A) a low viscosity first stage prepolymer having free NCO moieties and free OH moieties which is itself the reaction product of (a) a first diisocyanate containing NCO moieties of differing reactivity and (b) a polyhydric alcohol, in an OH:NCO ratio of about 0.55-4:1, so that only the more reactive NCO moieties are reacted with some of the OH moieties; and (B) a second diisocyanate containing NCO moieties which are more reactive than the less reactive NCO moieties of the first diisocyanate, in an OH:NCO ratio of from equimolar to an excess of NCO, so that the NCO moieties of said second diisocyanate react with said remaining free OH moieties of said first stage prepolymer, to form said isocyanate terminated polyurethane prepolymer. a first diisocyanate containing NCO moieties of differing reactivity and (b) a polyhydric alcohol, in an OH:NCO ratio of about 0.55-4:1, so that only the more reactive NCO moieties are reacted with some of the OH moieties; and (B) a second diisocyanate containing NCO moieties which are more reactive than the less reactive NCO moieties of the first diisocyanate, in an OH:NCO ratio of from equimolar to an excess of NCO, so that the NCO moieties of said second diisocyanate react with said remaining free OH moieties of said first stage prepolymer.