POLYURETHANE HOT-MELT ADHESIVE HAVING A LOW CONTENT OF DIISOCYANATE MONOMERS AND GOOD CROSS-LINKING SPEED

摘要

A moisture-cured hot-melt adhesive can be formulated as a PUR-HM that is R-40 classification-free and stable during storage and processing, having a residual monomer content of less than 1 wt. % and having good cross-linking density and full-curing speed. The hot-melt adhesive is particularly suitable for vehicle construction in industrial manufacture, in particular of automobiles, in the textile or furniture industry or in the packaging industry.

主权项

1. A moisture-curing hotmelt adhesive obtainable by a process comprising
A) reacting one or more polyols as component a) with one or more monomeric polyisocyanates as component b), the stoichiometric ratio of isocyanate groups to hydroxyl groups being greater than 1, to give a reaction product comprising an isocyanate-functional polyurethane prepolymer, B) adding at least one mercaptosilane of the formula (I) as component c)
HS—R3—Si(X)(3-a)(R2)a   (I)in which R2 is a linear or branched alkyl group having 1 to 10 C atoms, R3 is a linear or branched alkylene group having 1 to 10 C atoms, X is a hydrolyzable radical, and a has a value of 0, 1 or 2,to the reaction product and carrying out reaction to give a reaction product modified with the mercaptosilane, and C) adding an isocyanate-functional polyurethane prepolymer having a monomeric polyisocyanate content of below 1 wt % as component d) before, during and/or after the adding of the mercaptosilane to the reaction product or modified reaction product, the at least one mercaptosilane being added in an amount of 0.5 to 3.5 wt % and the isocyanate-functional polyurethane prepolymer as component d) being added in an amount of 10 to 50 wt %, based in each case on the total weight of the components a) to d).