Hydroxyl-Functionalised Polyurethane Hot Melt Prepolymer

A hydroxyl-functionalized polyurethane hotmelt prepolymer comprising the chemical reaction product of isocyanate-reactive starting materials with at least one isocyanate-containing starting material, wherein the isocyanate-reactive starting materials of the hydroxyl-functionalized polyurethane hotmelt prepolymer comprise at least one polypropylene glycol PI having a functionality of more than two and a number-average molar mass of greater than or equal to 3000 g/mol, at least one polypropylene glycol PII having a functionality of less than or equal to two and a number-average molar mass of less than or equal to 1000 g/mol, and at least one chain extender KI having a functionality of less than or equal to two and a number-average molar mass of less than or equal to 500 g/mol, and wherein the isocyanate-containing starting material of the hydroxyl-functionalized polyurethane hotmelt prepolymer comprises an aliphatic or alicyclic diisocyanate.