Abstract: A one-component-type composition for a polyurethane elastomer, comprising as a main component a polyurethane precursor containing a polyisocyanate component, and a compound having active hydrogen groups. The polyisocyanate component contains a polyisocyanate having at least a urethodione group (particularly urethodione and isocyanurate groups), and the compound (polyol or the like) having active hydrogen groups contains at least two active hydrogen groups in its molecule and has a molecular weight of 18 to 20000. The polyurethane precursor is obtained by reacting the polyisocyanate component and the compound having active hydrogen groups under the condition that the equivalent ratio of the active hydrogen group in the compound having active hydrogen groups to the isocyanate group in the polyisocyanate component exceeds 1.0. The equivalent ratio of the urethodione group to the active hydrogen group in the polyurethane precursor is from 0.25 to 1.0.

Abstract: A one-component type polyurethane adhesive: comprising, as a main component, a polyurethane precursor prepared by reaction of a polyisocyanate component (a) containing one or more polyisocyanate compounds (a-1) mention below and optionally one or more polyisocyanates (a-2) mention below with an active hydrogen compound (b) having a molecular weight of from 18 to 20,000 and having two or more active hydrogen groups in the molecule, at an equivalent ratio of the active hydrogen group of the active hydrogen compound component (b) to the isocyanate group of the polyisocyanate component (a) of more than 1.0; the polyurethane precursor containing a uretdione group and the active hydrogen group at an equivalent ratio of the uretdione group to the active hydrogen groups of from 0.25 to 1.0,(a-1): a polyisocyanate compound having at least a uretdione group in the molecule thereof, and(a-2): a polyisocyanate having two or more isocyanate groups in the molecule thereof.