| 主权项 |
1. 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. |
