Aqueous polycarbodiimide dispersion with improved storage stability, and method for producing same

A method for preparing an aqueous dispersion of hydrophilically modified polycarbodiimide resins, comprising:

• A) reacting a polyisocyanate in the presence of a carbodiimidization catalyst to obtain a polycarbodiimide;
• B) adding a compound that contains at least one group reactive toward isocyanate and/or carbodiimide groups during or after polycarbodiimide formation to form a hydrophilized polycarbodiimide;
• C) dispersing the hydrophilized polycarbodiimide in water to obtain a dispersion;
• and
• D) adding a salt component to at least one of:
• the water used to obtain the dispersion,
• the dispersion,
• the polyisocyanate, or
• the compound
• wherein the dispersion has an electrical conductivity in accordance with DIN EN 27888 and measured at 20° C. that is higher than that of a dispersion minus the salt component but otherwise identical,
• wherein the salt component comprises at least one salt having a cation and an anion that is present in its highest deprotonation level and having a pKB of ≥9,
• wherein, when the salt component comprises magnesium sulfate and/or calcium sulfate, at least one further anion having a pKB of ≥9 is present in its highest deprotonation level in the salt component, and
• wherein, when the salt component comprises aluminum(III) chloride in a content of ≥95 mol %, the electrical conductivity of the dispersion in accordance with DIN EN 27888 and measured at 20° C. is ≤1000% of the electrical conductivity of a dispersion minus the salt component but otherwise identical.