| abstract |
The present invention relates to a polymer matrix whose polymers have a hydrophobic character comprising 0.1 to 25% by weight, based on the mass of the total polymer matrix, of a mixing system comprising poly (1-vinyl-2-pyrrolidones) of the general formula with n = 350 to 13500 and / or their copolymers and water, wherein the weight ratio between PVP and water in the range of 1: 5 to 5: 1, preferably 1: 3 to 3: 1, in particular 1: 2 is selected. |