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Method for preparing high-polymer polylactic on Bitruder

A twin-screw extruder, high molecular weight technology, applied in the field of preparation of high molecular weight biodegradable material polylactic acid, can solve the problems of unsatisfactory industrialized production, difficult industrialization, complicated process and the like

Inactive Publication Date: 2008-06-18
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The patent document US5574129 introduces the method of melting and polycondensing lactic acid prepolymers on a twin-screw extruder to synthesize polylactic acid. The molecular weight can reach about 100,000, but the process is complicated and industrialization is difficult.
Patent document US5470944 introduces the method of preparing high molecular weight polylactic acid by chain extension method, the molecular weight is 25000-100000, but the industrial production is not ideal

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] In a 15L batch polymerization tank with a stirrer, add 8kg of D with a purity of 88%, L-lactic acid with Sb 2 o 3and ZnO as catalysts, adding 0.6wt% each, stirring well. Dehydrate at 100°C for 1.5 hours, then fill with nitrogen, raise the temperature to 125°C, and fill with nitrogen for 0.5 hours. Then turn off the nitrogen and vacuumize, the vacuum degree is 0.1Mpa, react at 145°C for 3 hours, and react at 155°C for 4 hours, then rise to 165°C and 180°C, and finally lower the temperature slowly. The total reaction time is 17 hours to remove 2.32kg of water, and get 5.2 kg of prepolymer with a weight average molecular weight of 15250.

[0033] Take 1000g prepolymer, add 0.5% SnCl 2 . Pentaerythritol is used as chain extender, and the molar ratio of -OH of pentaerythritol to -COOH of prepolymer is 0.4. The three are mixed evenly with a mixer and added to the twin-screw extruder. The chain extension reaction was carried out under the protection of nitrogen. The ext...

Embodiment 2～5

[0042] Get the 1000g prepolymer obtained in example 1, add 0.3% SnCl 2 . Using TDI as a chain extender, changing the molar ratio of -NCO / -OH. Prepolymer and SnCl 2 First use a stirrer to mix and add together, TDI is added with a peristaltic pump. The extruder is set up as follows:

[0043] Feeding rate: 1.5kg / h; Screw speed: 20rpm; Vacuum degree: -50mbar

[0044] Cylinder temperature: Zone 1 = 130°C

[0045] Zone 2 = 140°C

[0046] Zone 3-7 = 150°C

[0047] Zones 8 and 9 = 140°C

[0048] Zones 10 and 11 = 150°C

[0049] The residence time of polylactic acid is 12min, and weight-average molecular weight (Mw) is as follows:

[0050] -NCO / -OH molar ratio

Embodiment 6～8

[0052] Get the 1000g prepolymer obtained in Example 1, the catalyst consumption is 0.3%, and MDI is used as the chain extender, -NCO / -OH=1. Mix all three together.

[0053] The extruder is set up as follows:

[0054] Feeding rate: 1.5kg / h; Screw speed: 10rpm; Vacuum degree: -75mbar

[0055] Cylinder temperature: zone 1, zone 2 = 140°C

[0056] Zone 3-7 = 150°C

[0057] Zones 8 and 9 = 140°C

[0058] Zones 10 and 11 = 150°C

[0059] The residence time of polylactic acid is 20min, and weight average molecular weight (Mw) is as follows:

[0060] catalyst

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PUM

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Abstract

A process for preparing high molecular poly-lactic acid on the twin screw extruder is achieved by increasing the molecular weight of the poly-lactic acid by extending the chains of lactic acid preformed polymer on the twist screw extruder, which contains two steps: firstly, the preformed polymer of lactic acid whose weight mean molecular weight is 3000-50000 is produced by fasculation of lactic acid in the batch polymerization-autoclave; secondly, increasing the molecular weight of the produced preformed polymer to 180000 through chain extending. Its advantages include: improving the traditional synthetic method of the poly-lactic acid, settling the problem of low molecular weight, high price, no batch production, the manufacturing facility, and simple process with rapid reaction speed and high productive efficiency.

Description

technical field [0001] The present invention relates to the preparation method of high-molecular-weight biodegradable material polylactic acid, relate to the method for producing high-molecular-weight polylactic acid rapidly and continuously in particular and granulating it, this method comprises preparing lactic acid prepolymer by polycondensation reaction of cheap lactic acid, and The process of chain extension of prepolymers on a twin-screw extruder. Background technique [0002] There are two methods for the synthesis of polylactic acid, namely ring-opening polymerization and direct polycondensation. The ring-opening polymerization method first synthesizes lactide from lactic acid, and then prepares polylactic acid by ring-opening polymerization of lactide. There are mainly three ways: cationic polymerization, anionic polymerization and coordination polymerization. PLA. The ring-opening polymerization method has become increasingly mature in the laboratory. For example...

Claims

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Application Information

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IPC IPC(8): C08G63/06B29C47/40B29C48/40
CPCB29C48/40
Inventor 任杰廖文俊
Owner TONGJI UNIV
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