Reactive adhesives based on block copolymers

A process for preparing a reaction product of a block copolymer based on OH-functional polyolefin which is in unhydrogenated form and a cyclic ester in the form of a polyol having at least 1.8 OH groups and at least one isocyanate compound having at least two isocyanate groups, wherein the reaction is effected in the presence of a titanium-comprising catalyst and a sufficient amount of isocyanate compound is used that the ratio of OH groups to isocyanate groups is from 1:1.1 to 1:5, wherein the titanium is in the form of titanium tetramethoxide, titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetra-n-butoxide, titanium tetra-t-butoxide, titanium tetraphenoxide, titanium oxide acetylacetonate, titanium acetylacetonate or titanium dialkoxide based on diols, and

• wherein the hydroxyl-functional polyolefin used is a polybutadiene containing a 1,3-butadiene-derived monomer units
• wherein the monomer units (II), (Ill) and (IV) are blocks or in random distribution and, based on the polybutadiene, the percentage of the repeat unit (II)=10 to 40 mole percent, (Ill)=40 to 85 mole percent, (IV) is 5 to 40 mole percent, where a square bracket in the chosen formula representation of the 1,3-butadiene-derived monomer units (II), (Ill) and (IV) present in the polybutadiene shows that the bond endowed with the respective square bracket and the corresponding monomer unit is bonded via this bond to a further monomer unit or a hydroxy 1 group, and optionally, in addition to a proportion of up to 5 mole percent based on the polybutadiene, one or more branching structures
• are present, where “(C4H6)n” corresponds to a butadiene oligomer containing the repeat units (II), (Ill) and (IV) and the respective chain ends are OH groups.