| 摘要 |
The invention provides for the use of a copolymer, comprising a) 0.1 to 10 mol-%, based on the weight of the copolymer, of structural units derived from vinylphosphonic acid or of a salt thereof, b) 40 to 80 mol-%, based on the weight of the copolymer, of structural units derived from compounds of the formula (1), c) 1 to 50 mol-%, based on the weight of the copolymer, of structural units derived from compounds of the formula (5) in which X is OH or NR |
