Removable adhesive agent made of polyurethane

Contact adhesive based on a polyurethane obtained by reacting aliphatic or alicyclic polyisocyanate with a functionality of not more than 3 with a combination of polypropylene glycol-based triols with mol. wts. (Mn) of not more than 1000 (triol A) and at least 1000 (preferably at least 3000) (triol B) respectively, using an NCO/OH ratio of 0.8-1.15 (preferably 0.95-1.05) and an OH group ratio (A/B) of up to 12, with an organic bismuth compound as catalyst, preferably a bismuth carboxylate. Polyurethane-based pressure-sensitive adhesive (I), in which the polyurethane is obtained by reacting (a) aliphatic or alicyclic polyisocyanate(s) with a functionality of not more than 3 with (b) a combination of polypropylene glycol-based triols (A) and (B) with number-average mol. wts. (Mn) of not more than 1000 and at least 1000 (preferably at least 3000) respectively, where the ratio of OH groups in (A) to those in (B) = between more than 0 and 12, the ratio of NCO groups to total OH groups = 0.8-1.15, preferably 0.95-1.05, and the catalyst is or contains an organic bismuth compound, preferably a bismuth carboxylate or derivative thereof. An independent claim is included for a method for the production of (I) by (a) placing the premixed triols and the isocyanate component in separate tanks (with other ingredients as required), feeding the polyol and isocyanate components through the mixing head or mixing tube of a multi-component mixing/metering unit by means of a precision pump, transferring the reacting mixture immediately to a belt of carrier material (preferably moving at constant speed), hardening the polyurethane in a heating channel and then winding the coated material into a roll.