| 摘要 |
FIELD: chemistry. ^ SUBSTANCE: present invention relates to a method of preparing an aqueous agent for applying coating, as well as an aqueous agent obtained using said method, and use thereof as binder in single-component (1K)-systems and a two-component (2K)-system, and for obtaining a coating on soaking substrates. The method involves the following: (I) polyurethane dispersion which is free from solvent and N-methylpyrrolidone is prepared, where the solvent free dispersion is a dispersion containing 0.9 wt % or less solvent, and the polyurethane dispersion (I) is simultaneously or separately mixed with (II) 1-7 wt % monohydroxyl-functional ethylene- or propyleneglycol ester, as well as (III) other lacquer additives. Wherein I.1) at the first step a NCO-prepolymer solution is obtained in a solvent with concentration of 66-98 wt %, where the solvent has boiling point lower than 100C at nominal pressure, by reacting: (a) one or more polyisocyanates, (b) one or more polyols with average molecular weight Mn 500-6000, (c) one or more polyols with average molecular weight Mn 62-500, (d) one or more compounds containing a ion group or capable of forming an ion group and the NCO-prepolymer is free from a non-ionic hydrophilisising agent; I.2) at the second step the NCO-prepolymer I.1) is dispersed in water, where before, during or after dispersion, ion groups are at least partially neutralised; I.3) at the third step the chain is elongated by (e) one or more polyamines with average molecular weight Mn less than 500; and l.4) at the fourth step, the solvent is completely removed by distillation. ^ EFFECT: obtaining an aqueous agent for applying a coating, having improved film-forming properties, as well as obtaining coatings therefrom, having good chemical resistance and pendulum hardness higher than 75 seconds. ^ 13 cl, 5 ex, 4 tbl |
