GRAFT POLYMERS, CONTAINING POLYVINYL ACETAL GROUPS, ON POLYURETHANE GRAFTING SUBSTRATES, PROCESSES FOR THE PREPARATION THEREOF, AND THE USE THEREFOR

摘要

Polymers containing polyvinyl acetal groups and acetalated polyvinyl alcohol groups on polyurethane graft bases can be prepared by known methods by reacting graft polymers which contain vinyl alcohol groups on polyurethane graft bases with aldehydes. Suitable aldehydes are all known aldehydes which are capable of acetalation reactions.
The polyurethane graft bases contain at least 2 urethane groups in the molecule and units of diisocyanates and diols, and polymer radicals comprising units of vinyl carboxylates having 3 to 20 C atoms and/or hydrolysis products thereof and optionally further monomer units are grafted onto the polyurethane graft bases. A proportion of the vinyl alcohol units in the hydrolysed or partially hydrolysed graft polymers before acetalation is > 10 % by weight.
The content of residual non-acetalated vinyl alcohol units in the acetalated polymer is > 7.5 mol-%, based on the molar content (= 100 mol-%) of vinyl alcohol units in the starting graft polyvinyl alcohol before acetalation.
Use of the graft polyvinyl acetals as a constituent of coating compositions, as a binder constituent for diverse substrates, as a material for thermoplastic mouldings and as an intermediate-layer film in laminated glasses.