Curing Compositions Having Low-Free Amounts of Methylenedianiline

A process for preparing a curing composition comprising an inert liquid carrier, a coordination complex of 4,4′-methylenedianiline and an alkali metal salt;

• and less than 1000 wppm of free methylenedianiline, said process comprising:
• A) adding an initial methylenedianiline, wherein 99.1% or more of the initial methylenedianiline consists of 4,4′-methylenedianiline and from 0.9% to 0.01% of the initial methylenedianiline is one or more of 2,2′-methylenedianiline, 2,4′-methylenedianiline and N-methyl-4,4′-methylenedianiline to a mixture comprising
• i) an alkali metal salt selected from the group consisting of sodium chloride, sodium bromide, sodium iodide, lithium chloride, lithium bromide, lithium iodide;
• ii) one or more inert liquid carrier comprising a plasticizer selected from the group consisting of esters of polycarboxylic acids and monohydric alcohols or phenols, and esters of polyols and monocarboxylic acids;
• iii) one or more surfactant selected from the group consisting of lecithin, polyoxypropylated quaternary ammonium halides, and phosphated glycerides:
• and
• iv) brine or water,
• to form the coordination complex;
• B) removing water from the mixture comprising the coordination complex to form a dry stage interniediate;
• C) adding an isocyanate compound to the dry stage intermediate to react with residual methylenedianiline,
• wherein no surfactant is added during or after addition of an isocyanate compound to the dry stage intermediate.