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Melt/solid state polycondensation preparation method for polylactic acid

A technology of solid-state polycondensation and polylactic acid, applied in the field of polylactic acid preparation, can solve problems such as high cost, difficult continuous production, and long reaction time

Active Publication Date: 2011-05-04
CHINA PETROLEUM & CHEM CORP +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] The technical problem to be solved by the present invention is that there are problems in the prior art that the reaction time is long, continuous production is difficult or the cost is high, and a new method for preparing polylactic acid by melting / solid phase polycondensation is provided

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Add 300 grams of 90% aqueous lactic acid solution and 1.08 grams of p-toluenesulfonic acid (catalyst A, 0.4%) in a 500 milliliter four-necked flask, vacuumize to an absolute pressure of 15000 Pa, and heat to 140 ° C for 2 hours of reaction; then, pump Vacuum to an absolute pressure of 400 Pa, and heat to 160°C, react for 2 hours, and the number average degree of polymerization is 20.

[0021] Add 1.08 grams of stannous chloride dihydrate (catalyst B, 0.4%), install a reflux condenser, control the reflux condenser jacket water temperature to 83 ° C, vacuumize to an absolute pressure of 200 ± 50 Pa, and heat the material to 180 ± 2 °C, reacted for 4 hours to obtain polylactic acid with a molecular weight of 21,000.

[0022] Cool, pulverize and sieve, take 5 grams of samples with a particle size of 0.4-0.5 mm, and crystallize at 70°C for 1 hour in a nitrogen atmosphere.

[0023] Then put about the sample into the solid-phase polycondensation reactor, heat it in an oil bat...

Embodiment 2

[0025] Add 300 grams of 90% aqueous lactic acid solution and 0.54 grams of p-toluenesulfonic acid (catalyst A, 0.2%) in a 500 milliliter four-necked flask, vacuumize to an absolute pressure of 13000 Pa, and heat to 140 ° C for 2 hours of reaction; then, pump Vacuum to an absolute pressure of 400 Pa, and heat to 160°C, react for 2 hours, and the number average degree of polymerization is 12.

[0026] Add 1.08 gram of stannous chloride dihydrate (catalyst B, 0.4%) and 0.54 gram of p-toluenesulfonic acid (catalyst A, 0.2%), install reflux condenser additionally, control reflux condenser jacket water temperature 83 ℃, vacuumize to The absolute pressure is 200 Pa, and the material is heated to 180° C., and reacted for 5 hours to obtain a polylactic acid prepolymer with a weight average molecular weight of 22,000.

[0027] Cool, pulverize, and sieve, take 5 grams of samples with a particle size of 0.4 to 0.5 mm, and crystallize at 110° C. for 30 minutes in a nitrogen atmosphere.

[0...

Embodiment 3

[0030] Add 300 grams of 90% aqueous lactic acid solution and 1.08 grams of p-toluenesulfonic acid (catalyst A, 0.4%) in a 500 milliliter four-necked flask, vacuumize to an absolute pressure of 14000 Pa, and heat to 130 ° C for 2 hours of reaction; then, pump Vacuum to an absolute pressure of 400 Pa, and heated to 150 ° C, reacted for 2 hours, the number average degree of polymerization was 13.

[0031] Add 1.08 grams of stannous chloride dihydrate (catalyst B, 0.4%), add a reflux condenser, control the reflux condenser jacket water temperature to 83°C, vacuumize to an absolute pressure of 200Pa, and heat the material to 180°C, react 8 hours, polylactic acid was obtained with a weight average molecular weight of 42,000.

[0032] Cool, pulverize, and sieve, take 5 grams of samples with a particle size of 0.4 to 0.5 mm, and crystallize at 70°C for 2 hours in a nitrogen atmosphere.

[0033] Then put about the sample into a solid-phase polycondensation reactor, heat it in an oil b...

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Abstract

The invention relates to a melt / solid state polycondensation preparation method for polylactic acid, which mainly solves the problems of long reaction time, difficult continuous production or high cost in the prior art. The method comprises the following steps of: 1) performing a dehydration oligomerization reaction of lactic acid at the temperature of between 100 and 160 DEG C under the absolute pressure of between 6,000 and 25,000 Pa and under the action of a catalyst A for 0.5 to 5 hours first, and continuing the ehydration oligomerization reaction at the temperature of between of 120 and 180 DEG C under the absolute pressure of between 200 and 1,500 Pa and under the action of the catalyst A for 0.5 to 5 hours to generate a product I; 2) performing a melt polycondensation reaction of the product I at the reaction temperature of between 150 and 200 DEG C under the absolute pressure of between 30 and 600 Pa and under the action of a catalyst B for 0.5 to 15 hours to generate a polylactic acid prepolymer and lactide serving as a by-product, and refluxing the lactide to a reaction mixture at the reflux temperature of between 70 and 95 DEG C; 3) pelletizing the polylactic acid prepolymer obtained in the step 2), and crystallizing in an inertia airflow at the temperature of between 50 and 130 DEG C for 0.5 to 10 hours; and 4) performing a solid state polycondensation reaction of the polylactic acid prepolymer processed in the step 3) in the inertia airflow at the temperature of between 120 and 170 DEG C for 5 to 40 hours to obtain the polylactic acid. The technical scheme of the invention better solves the problem, and can be used for the industrial production of the polylactic acid.

Description

technical field [0001] The invention relates to a method for preparing polylactic acid, in particular to a method for preparing polylactic acid by melt / solid phase polycondensation. Background technique [0002] Polylactic acid is an important biodegradable polymer material. It has excellent physical and mechanical properties, biodegradability and biocompatibility, and can be processed by traditional methods. It has good application prospects in the fields of agriculture, packaging materials, daily life, clothing and biomedical materials. . [0003] Polylactic acid can be synthesized by ring-opening polymerization of lactide, a dimer of lactic acid, and polycondensation of lactic acid. High-molecular-weight polylactic acid can be easily prepared by ring-opening polymerization, and industrialized production has been realized, but the production cost is relatively high. In comparison, the melt / solid-state polycondensation method has attracted much attention because of its l...

Claims

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Application Information

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IPC IPC(8): C08G63/08C08G63/06C08G63/78C08G63/80
Inventor 吴林波候宏兵宋方超夏燕敏周文乐
Owner CHINA PETROLEUM & CHEM CORP
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