Лако-красочные материалы — производство

The addition of hydrogen sulfide to the hydrocyanocarbodiphenyli­mide takes place very easily if the latter is finely powdered. The material is therefore ground in a roller mill or sifted. 200 grams of the finely divided material is emulsified by vigorous stirring at 35°C. in 500 grams of yellow ammonium sulfide solution. (The reaction can be greatly accelerated by the addition of an equal volume of alcohol.) The am­monium sulfide solution is prepared by passing 35 grams of hydrogen sulfide into a mixture of 460 grams of 20 per cent aqueous ammonia and 25 grams of powdered sulfur. If the hydrocyanocarbodiphenylimide is powdered finely enough, the addition of hydrogen sulfide takes place quantitatively within 12 hours, as shown by the fact that a washed sam­ple is soluble in dilute hydrochloric acid. The product is filtered off and washed thoroughly with water. It is sufficiently pure for use in the next step. The yield is about 220 grams. It crystallizes from alcohol in yellow prisms melting at 162°.