Production of polysuccinimide or maleic amide acid

PROBLEM TO BE SOLVED: To obtain a polysuccinimide by introducing molten maleic anhydride in a state of a fine liquid or vapor into an atmosphere comprising an NH 3 gas or a gaseous mixture thereof with another gas and having a specified temperature. SOLUTION: Maleic anhydride molten by heating to 60-120°C in a hold tank 1 is sent via a protected pipe to a nozzle 2 and sprayed into a spray drying tower 3 in which an NH 3 gas is flowing continuously and downwardly at a temperature of 10-250°C under a pressure of 0.01-20 MPa. The formed polysuccinimide or maleic amide acid is deposited in the cone of the tower 3 and is withdrawn through a chute-off slide 5. The gas stream leaving the tower 3 is stripped of entrained particles in a cyclone 6 and a feeder 7, while the NH 3 stripped of the water formed by the reaction with a scrubber 8 is returned to the tower 3. The polysuccinimide together with added NaOH 12 is hydrolyzed in an agitation tank 13 at about 20°C, and the formed polysodium aspartate together with preheated air 15 is sprayed into another spray drying tower 14 to obtain polyaspartic acid. COPYRIGHT: (C)1996,JPO