反应详情

Type B is the sodium salt of a copolymer of maleic acid and 2,4,4-trimethylpent-1-ene obtained by 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 220 parts of water and 200 parts of 50% strength by weight sodium hydroxide solution, the mixture is stirred at 1000C until a virtually clear aqueous solution is obtained (about 4 h). The solids content is then adjusted to 25% using water. The pH of the solution is 10. 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.