反应详情

Type A is the ammonium salt of a copolymer of maleic acid and 2,4,4-trimethylpent-1-ene obtained by ammoniacal hydrolysis of a copolymer of maleic anhydride and 2,4,4-trimethylpent-1-ene. Latter copolymer is obtainable in accordance with Example 3 of EP-A 9169. Instead of isolating the unhydrolyzed copolymer by spray drying as in Example 3 of EP-A 9169, 325 parts of water are added to the suspension and excess diisobutene is distilled off by steam distillation (bath temperature 80° C.). When an internal temperature of 98° C. is reached, steam is passed in for a further 1 h. Following the addition of a further 200 parts of water and 170 parts of 25% strength by weight ammonia, the mixture is stirred at 60° C. until a virtually clear aqueous solution is obtained (about 1 h). The solids content is then adjusted to 22% using water. The pH of the solution is 9. The K value of the copolymer (determined in accordance with Fikentscher as a 1% strength by weight solution in dimethylformamide) is in the range of 30–40.