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Melt/solid-phase polycondensation preparation method of polylactic acid material with high molecular weight and high crystallinity

A polylactic acid material and high molecular weight technology, which is applied in the field of melt/solid phase polycondensation preparation of high molecular weight and high crystallinity polylactic acid, can solve the problem that the reaction rate is difficult to meet the requirements of industrialization, the energy consumption of secondary melt blending is high, and the polycondensation process can be improved. Reduce the cost of lactic acid and other issues, achieve the effect of shortening the melt polycondensation time, increasing the solid phase polycondensation rate, and shortening the dehydration time

Active Publication Date: 2011-04-06
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] According to the public documents of the existing polylactic acid melt / solid phase polycondensation, the reaction is slow, the reaction time is long, and its reaction rate is difficult to meet the requirements of industrialization, which needs to be improved urgently.
[0009] At the same time, polylactic acid has slow crystallization, low melting point and poor heat resistance
Although the crystallization rate of polylactic acid can be improved by adding a crystallization accelerator through melt blending, the energy consumption of the secondary melt blending is high, which increases the cost of polylactic acid manufacturing.

Method used

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  • Melt/solid-phase polycondensation preparation method of polylactic acid material with high molecular weight and high crystallinity

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] Add 300 grams of 90% lactic acid aqueous solution and 1.08 grams of p-toluenesulfonic acid (0.4% by weight of lactic acid weight) 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, evacuate to an absolute pressure of 400Pa, and heat to 160°C, react for 2 hours, and the number-average degree of polymerization of the product is 20.

[0034] Add 1.08 grams of stannous chloride dihydrate (the weight percent content of lactic acid weight is 0.4%), install a reflux condenser additionally, control the reflux condenser jacket water temperature 83 ℃, vacuumize to an absolute pressure of 200Pa, and heat the material to 180 °C, reacted for 4 hours, cooled, pulverized, and sieved to obtain polylactic acid prepolymer particles with a weight average molecular weight of 21,000.

[0035] Take 5 grams of a sample with a particle size of 0.4-0.5 mm, and crystallize at 70° C. for 1 hour in a nitrogen atmo...

Embodiment 2

[0038] Add 300 grams of 90% lactic acid aqueous solution and 1.08 grams of p-toluenesulfonic acid (0.4% by weight of lactic acid weight) 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, evacuate to an absolute pressure of 400Pa, and heat to 150°C, react for 2 hours, and the number-average degree of polymerization of the product is 13.

[0039] Add 1.08 grams of stannous chloride dihydrate (the weight percent content of lactic acid weight is 0.4%), install a reflux condenser additionally, control the reflux condenser jacket water temperature 83 ℃, vacuumize to an absolute pressure of 200Pa, and heat the material to 180 °C, reacted for 10 hours, cooled, crushed, and sieved to obtain polylactic acid prepolymer particles with a weight average molecular weight of 42,000.

[0040] Take 5 grams of a sample with a particle size of 0.4-0.5 mm, and crystallize at 70° C. for 1 hour in a nitrogen atmosp...

Embodiment 3

[0043] Add 300 grams of 90% lactic acid aqueous solution and 1.08 grams of p-toluenesulfonic acid (0.4% by weight of lactic acid weight) in a 500 milliliter four-necked flask, vacuumize to an absolute pressure of 15000 Pa, and heat to 150 ° C for 1 hour Then, evacuate to an absolute pressure of 300Pa, and heat to 170°C, react for 2 hours, and the number-average degree of polymerization of the product is 27.

[0044] Add 1.08 grams of tin protochloride dihydrate (the weight percent content of lactic acid weight is 0.4%), install a reflux condenser additionally, control the reflux condenser jacket water temperature 83 ℃, vacuumize to an absolute pressure of 100Pa, and heat the material to 180 ℃, reacted for 4 hours, cooled, crushed, and sieved to obtain polylactic acid prepolymer particles with a weight average molecular weight of 23,000.

[0045] Take 5 grams of a sample with a particle size of 0.4-0.5 mm, and crystallize at 90° C. for 1 hour in a nitrogen atmosphere.

[0046]...

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Abstract

The invention discloses a melt / solid-phase polycondensation preparation method of a polylactic acid material with high molecular weight and high crystallinity. The method comprises the following steps: adding 0.1-1% of protonic acid catalyst into the aqueous solution of lactic acid or the mixed solution of the aqueous solution of lactic acid and the silica nano particle silica sol containing 0.1-10% of lactic acid by weight, and dehydrating; performing an oligomerization reaction; adding 0.1-1% of lewis acid catalyst for a melt polycondensation reaction; adding 0-5% of crystallization accelerator, mixing uniformly and granulating, and crystallizing in an inert gas flow; and finally performing a solid-phase polycondensation reaction in the inert gas flow to obtain polylactic acid with high molecular weight and high crystallinity. In the invention, as two catalysts with different properties are added at different steps, the dehydration time is shortened, racemization is suppressed and the molecular weight and crystallinity of an oligomer are improved; moreover, the crystallization accelerator is introduced in situ, and thus the crystallinity and melting point of the polylactic acid are improved at low cost; and finally the heat resistance is improved. The invention is favorable for realizing industrialization.

Description

technical field [0001] The invention relates to a preparation method of polylactic acid material, in particular to a preparation method of melt / solid phase polycondensation of high molecular weight and high crystallinity polylactic acid. 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 is easily prepared by ring-opening polymerization, and industrialized production has been realized, but the production cost is relatively high. In 2000, J.Polym.Sci.Part A: Polym.Chem. (38:1673-9, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G63/06C08G63/78C08G63/80C08G63/87C08G63/85C08K3/36C08K13/02
Inventor 吴林波彭博马朝勤宋方超侯宏兵孙湘盈
Owner ZHEJIANG UNIV
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