反应详情

206 g of a polyester from adipic acid and ethylene glycol having a molecular weight of 2060 are heated for 30 minutes to 110°C to remove any water dissolved therein. Subsequently 74 g of an allophanate diisocyanate mixture are added at 70°C. The diisocyanate mixture had previously been obtained by reacting ethoxylated n-butanol (molecular weight 2030) with toluylene diisocyanate at a molar ratio of 1:5 and has an NCO-content of 16,9 % by weight. Subsequent to the addition of the diisocyanate mixture the reaction system is heated for 1 hour to 110°C until the theoretical NCO-value of 1,5 % by weight is reached. The prepolymer obtained is dissolved in 800 ml of acetone. A solution of 1,15 g of 1,2-propylene diamine in 30 ml of water is added at 50°C. Thereafter a solution consisting of 16 g of an oligo amide obtained from 1-aminomethyl-5-amino-1,3,3-trimethylhexane and adipic acid in a molar ratio of 4:3, 16 g of ethyl acetate and 100 ml of acetone is added. The reaction mixture is allowed to react for 5 minutes at 50°C. Thereafter 400 ml of water are added and the acetone is distilled off under vacuo. An aqueous dispersion is obtained the solids of which contain 14,8 % by weight of ethylene oxide units. A film which is obtainable by pouring the dispersion on a glass plate and evaporating the water is smooth and elastic.

1. customThe prepolymer obtained