Aqueous fungicidal composition and use thereof for combating harmful microorganisms

A process for the protection of cellulose-comprising materials from infection by microorganisms comprising the treatment of the cellulose-comprising material with an aqueous active substance composition,

• said composition comprising (a) at least one fungicidal organic active substance with a solubility in water of less than 1 g/l at 25° C./1013 mbar, and (b) a finely-divided polymer with an average particle size, determined by dynamic light scattering, of 10 to 250 nm, in which the polymer particles comprise the active substance, the polymer having a glass transition temperature of at least 10° C. and being formed from ethylenically unsaturated monomers M consisting of:
• from 70 to 99.5% by weight, based on the total amount of the monomers M, of at least one neutral monoethylenically unsaturated monomer M1 with a solubility in water of not more than 30 g/l at 25° C., which is selected from styrene and esters of monoethylenically unsaturated mono- or dicarboxylic acids with C1-C10-alkanols or C5-C8-cycloalkanols, and
• from 0.50 to 30% by weight, based on the total amount of the monomers M, of at least one ethylenically unsaturated monomers M2, which is selected from:
• monoethylenically unsaturated monomers M2a exhibiting at least one acid group or at least one anionic group, the amount of monomers M2a being not more than 20% by weight, based on the total amount of the monomers M;
• monoethylenically unsaturated neutral monomers M2b exhibiting a solubility in water of at least 50 g/l at 25° C., the amount of monomers M2b being not more than 10% by weight, based on the total amount of the monomers M and
• not more than 2% by weight, based on the total amount of the monomers M, of monomers having two or more nonconjugated ethylenically unsaturated double bonds,
• wherein the aqueous active substance composition is obtained by a process comprising radical aqueous emulsion polymerization of an oil-in-water emulsion of the monomers M, the monomer droplets of the oil-in-water emulsion to be polymerized comprising the fungicidal active substance in dissolved form.