Synthetic method of high-molecular-weight polylactic acid
A high-molecular-weight, synthetic method technology, applied in the field of high-molecular-weight polylactic acid synthesis, can solve the problems of restricting the industrial production and market promotion of polylactic acid biodegradable materials, difficulty in injection molding, and low synthetic molecular weight, etc. Rate and controllability, controllable reaction conditions, effect of increasing molecular mass
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[0024] A method for synthesizing high-molecular-weight polylactic acid, comprising the following steps: feeding nitrogen into a reactor, mixing lactide with an initiator and a catalyst, raising the temperature so that the lactide undergoes ring-opening polymerization in the reactor, and prepares high-molecular-weight polylactic acid. The polylactic acid of molecular weight; The initiator is potassium benzoate, potassium phenate, tetramethylguanidine, triethoxyammonium bromide, boron trifluoride, trifluoroacetic acid, 4-nitro-N-methylethoxyphthaloyl One or a combination of two or more of imine, 5-aminoimidazole-4-carboxamide, and 5-amino-2-nitrobenzoic acid.
[0025] The ring-opening polymerization of lactide not only involves the activity of the monomer, but also the activity of the initiator. Therefore, the catalyst's catalysis of the monomer and the activity of the initiator have a great influence on the ring-opening polymerization of lactide. Selecting a suitable initiator,...
Embodiment 1
[0036] The L-lactic acid and stannous octoate catalyst with a molecular weight of 2500g / mol are 1000:2 according to the molar ratio of the substance, and the oligomeric L-lactic acid is added in the high-pressure glass reactor, and then the stannous octoate catalyst is added, and the reaction temperature is 230 °C, under the condition of vacuum degree of 0.02Mpa, react for 2h; obtain L-lactide by vacuum distillation, wash with dichloromethane for 3 times, dissolve unreacted lactic acid, filter with suction, and dry under vacuum at 50°C After 10 hours, the yield of L-lactide was 91.7%, and the purity was 99.3%.
Embodiment 2
[0038] The L-lactic acid with a molecular weight of 3000g / mol and the catalyst are 1000:3 according to the ratio of the substances, and the L-lactic acid is added to the high-pressure glass reactor, and then the stannous octoate and tin tetrachloride catalyst are added. The reaction temperature is 120 ℃, under the condition of vacuum degree of 0.06Mpa, react for 5h; obtain L-lactide by vacuum distillation, wash twice with chloroform, dissolve unreacted lactic acid, filter with suction, vacuum dry, vacuum dry The temperature was 60° C., the vacuum drying time was 8 hours, and the yield of L-lactide was 92.5%, and the purity was 99.1%.
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