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Process for preparing poly-lacti acid

A polylactic acid and said technology, applied in the field of polylactic acid preparation, can solve the problems of high cost of polylactic acid, high production cost, large equipment investment, etc., and achieve excellent biocompatibility, reduced production cost, and save manpower and material resources. Effect

Inactive Publication Date: 2004-12-29
CHENDU NEW KELI CHEM SCI CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method can increase the relative molecular weight of polylactic acid, and can obtain polylactic acid with higher molecular weight. The molecular weight can generally be more than 100,000, and the purity of raw materials is not high, and even leftovers and waste materials can be used, but the disadvantage of this method is that Lactide must be purified before it can be polymerized into high molecular weight polylactic acid. The equipment investment is large, the technical requirements are high, continuous production cannot be carried out, and the catalyst residue in the product is high.
[0007] The technical shortcomings of the above two preparation methods are that the production process of polylactic acid is complicated, the process is long, the raw material requirements are high, the equipment investment is large, the technical requirements are high, and continuous production cannot be carried out, so the production cost is high. The cost of polylactic acid obtained is much higher than that of ordinary plastic materials, so it is only used in medical and some high-end packaging industries, and the application in other fields is almost blank, which is an important factor that seriously restricts the promotion and use of polylactic acid

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] After preheating the co-rotating intermeshed twin-screw extruder with length / diameter ratio 50 / 1 by corresponding reaction temperature, 40Kg L-L type lactide lactic acid prepolymer (purity 85%), 200g butyltin and 150g Phosphorous acid is mixed evenly in the container, then injected into the feeder, and reacted in the extruder with the temperature sections of each zone set in sequence as follows:

[0026] 130 140 150 160 175 170 160 150 140 135 (℃)

[0027] The first temperature section The second temperature section The third temperature section The fourth temperature section

[0028] The main engine speed of the extruder is 120r / min, the first-level vacuum degree set in the third temperature section is 0.02-0.06MPa, the second-level vacuum degree set in the fourth temperature section is 0.005-0.01Mpa, and the fourth temperature at the end of the extruder Inject H at a rate of 0.002g / hour 2 The molecular weight is adjusted, and the reaction time is 15-30 m...

Embodiment 2

[0030] After preheating the co-rotating intermeshed twin-screw extruder with the length / diameter ratio of 48 / 1 according to the corresponding reaction temperature, 50Kg of D-D type lactide lactic acid prepolymer (purity 85%), 250g diethyl Hexanoic acid divalent tin salt and 200g triphenylphosphine are mixed uniformly in container, inject feeder, carry out reaction in the extruder that each zone temperature section is arranged successively in the following manner:

[0031] 140 150 160 170 180 190 185 170 160 150 (℃)

[0032] The first temperature section The second temperature section The third temperature section The fourth temperature section

[0033] The main engine speed of the extruder is 150r / min, and the primary vacuum degree set in the third and fourth temperature sections is 0.02-0.06MPa, and the secondary vacuum degree is 0.005-0.01Mpa. Inject H at the fourth temperature section at the end of the extruder in an amount of 0.008g / hour 2 Carrying out molecu...

Embodiment 3

[0035] After the co-rotating intermeshed twin-screw extruder with length / diameter ratio of 52 / 1 is preheated according to the corresponding reaction temperature, 45Kg of lactic acid oligomers (commercially available, purity 85%) with a degree of polymerization of 20, 225g- Butyl tin and 175g phosphorous acid are mixed homogeneously in container, inject feeder then, carry out reaction in the extruder that each zone temperature section is arranged successively in the following manner:

[0036] 135 145 150 160 170 180 175 160 150 140 (℃)

[0037] The first temperature section The second temperature section The third temperature section The fourth temperature section

[0038] The main engine speed of the extruder is 180r / min, the first-level vacuum degree set in the third temperature section is 0.02-0.06MPa, and the second-level vacuum degree set in the fourth temperature section is 0.005-0.01Mpa. Inject H at the fourth temperature section at the end of the extruder a...

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Abstract

The polylactic acid preparing process includes injecting material mixture comprising lactic acid pre-polymer, tin chloride or alkyl compound as catalyst and phosphorous acid or triphenyl phosphoric acid as stabilizer into preheated double screw extruder with length / diameter ratio over 40; and continuous kneading and extruding reaction at four temperature sections with the third and the fourth sections being in 0.005-0006 MPa pressure and connected with a volatile eliminating device and having certain amount of hydrogen as molecular weight regulator injected continuously. The reaction period is 5-30 min. The said process has the advantages of once completion of all the reactions, high molecular weight of the produced polylactic acid and lowered production cost.

Description

technical field [0001] The present invention relates to a preparation method of polylactic acid. Specifically, a twin-screw reaction extruder is used as a reactor, and processes such as polymerization reaction, monomer and by-product extraction, molecular weight control, and product purification are carried out in the reaction extruder. The process is completed at one time, and high molecular weight polylactic acid products are obtained. Background technique [0002] Polylactic acid is a kind of high molecular polymer chemically synthesized with microbial fermentation products as monomers. It is non-toxic, non-irritating, and has excellent biocompatibility, biodegradable absorption, high strength, and good plasticity. One of the most widely used synthetic degradable polymers in medicine, it can be used as surgical sutures, orthopedic materials, artificial skin and drug slow-release agents in medical and health care, and can be used in agriculture, fishery, forestry, food ind...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B29C47/40C08G63/02
Inventor 陈庆郭林陈兵宴佑东
Owner CHENDU NEW KELI CHEM SCI CO LTD
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