Preparation method for biobased polyurethane elastic fibers

A preparation method for biobased polyurethane elastic fibers, comprising the following steps:

• step A:
• adding sucrose and glycerol in a molar ratio of 1-2:1 into a reaction vessel, and adding dimethylamine with an amount of 30-50% of a total amount of dimethylamine, under vacuum conditions, raising a temperature to 85-95° C. and reacting for 1-1.5 hours;
• adding epoxypropane at a rate of 5-10 mL/min-1 with an amount of 10-30% of a total amount of epoxypropane;
• a total amount of the epoxypropane is 2-3 times a mass of the sucrose;
• maintaining the temperature at 90-100° C., vacuum ageing for 2-3 hours, then raising the temperature to 120-130° C. and keeping a pressure constant at 0.25-0.3 MPa;
• adding the remaining dimethylamine and continue adding the remaining epoxypropane at a rate of 5-10 mL/min-1;
• continuing the reaction until a pressure inside the reactor becomes a negative pressure, stopping the reaction, and continuing aging for 2-3 hours;
• controlling the temperature at 80-90° C., adding 50-60 g of oxalic acid aqueous solution with a mass concentration of 11%-12%, and adding a mixture of magnesium silicate and aluminum silicate;
• a mass concentration of the mixture of magnesium silicate and aluminum silicate is 0.1-0.2% of a total amount of sucrose, glycerol, and epoxypropane;
• a mass concentration of dimethylamine is 1-3% of a total amount of sucrose, glycerol, and epichlorohydrin;
• then stirring for 20-30 minutes, filtering, vacuum dehydration, and drying at 60-70° C. to obtain polyether polyol;
• step B:
• adding solvent N, N-dimethylacetamide, polyether polyol and polyisocyanate from step A to the reaction tank, a solvent mass concentration is 45%-65%, a molar ratio of polyether polyol and polyisocyanate is 1:1.5-1:2, a reaction temperature is 45-60° C., and reacting in a nitrogen atmosphere for 2-3 hours to obtain a prepolymer solution;
• when the prepolymer solution is cooled to 10-20° C., a mixed amine solution is added for chain extension reaction and chain termination reaction to form a polyurethane solution;
• a mass fraction of the mixed amine solution in the polyurethane solution is 5-10%;
• adding p-toluenesulfonyl semicarbazide with a mass concentration of 0.05-0.08% of polyurethane solution, stirring and mixing evenly, then adding aluminum methylene (2, 4-di-tert-butylphenoxy) phosphate with a mass concentration of 0.1-0.5% of polyurethane solution, mixing and maturing for 20-24 hours, and obtaining the spinning solution after defoaming;
• by using dry spinning technology, the spinning solution is spun and oiled to produce the biobased polyurethane elastic fibers.