Pressure-sensitive adhesive from a resin-modified polyurethene

A pressure-sensitive adhesive comprising a mixture of a chemically crosslinked polyurethane and at least one hydrocarbon resin, the chemically crosslinked polyurethane being composed of the following starting materials which in the stated proportions are reacted with one another catalytically in the presence of the at least one hydrocarbon resin:

• a) at least one aliphatic or alicyclic polyisocyanate whose functionality is in less than or equal to three,
• b) a combination of at least one polypropylene glycol diol and one polypropylene glycol triol, the ratio of the number of isocyanate groups to the total number of hydroxyl groups being between 0.8 and 1.15, and the ratio of the number of hydroxyl groups in the diol component to the number of hydroxyl groups in the triol component being between 0.8 and 9.0,
• and the diols and triols alternatively being selected and combined as follows:
• diols having a mean, number-averaged molecular weight Mn of less than or equal to 1000 are combined with triols whose mean, number-averaged molecular weight Mn is greater than or equal to 1000,
• diols having a mean, number-averaged molecular weight of greater than 1000 are combined with triols whose mean, number-averaged molecular weight is less than 1000,
• wherein at least one hydrocarbon resin is a monomer resin of the styrene/α-methylstyrene type having a mean, number-averaged molecular weight Mn of between 200 and 6000, the weight fraction of the resin in the mixture being greater than 0% and ranging up to a maximum of 55%.