CN1247653C - Process for direct preparation of poly-lactic acid from lactic acid by melt/solid phase polycondensation - Google Patents
Process for direct preparation of poly-lactic acid from lactic acid by melt/solid phase polycondensation Download PDFInfo
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- CN1247653C CN1247653C CN 200410013544 CN200410013544A CN1247653C CN 1247653 C CN1247653 C CN 1247653C CN 200410013544 CN200410013544 CN 200410013544 CN 200410013544 A CN200410013544 A CN 200410013544A CN 1247653 C CN1247653 C CN 1247653C
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Abstract
The present invention provides a method for directly preparing poly-lactic acid from lactic acid by melt/solid phase polycondensation, which relates to a method for preparing poly-lactic acid. The present invention aims to provide a method for directly preparing poly-lactic acid from lactic acid by melt/solid phase polycondensation. In the method, poly-lactic acid is prepared by the following steps: a. lactic acid ester or a mixture of lactic acid and lactic acid ester is used as a raw material, an inert gas is led into the raw material, reaction temperature is controlled at 100 to 160 DEG C, and lactic acid oligomer is obtained via prepolymerization at a pressure of 30 to 760 mmHg; b. a catalyst is added into the lactic acid oligomer, reaction temperature is controlled at 120 to 190 DEG C, the oligomer is processed via melting polymerization at a pressure of 1 to 20 mmHg, the reaction temperature is subsequently decreased, and the poly-lactic acid is obtained with the reaction temperature controlled at 100 to 110 DEG C after being cooled; c. finally, the reaction temperature is controlled at 100 to 175 DEG C, the pressure is from 0.5 to 10 mmHg, and poly-lactic acid solid with high molecular weight can be obtained via solid phase polymerization. The present invention has the advantages of simple process, low cost and little corrosiveness.
Description
Technical field
The present invention relates to a kind of preparation method of poly(lactic acid), be specifically related to a kind of synthesis technique for preparing poly(lactic acid) by fusion/process for solid state polycondensation.
Background technology
Poly(lactic acid) is a kind of synthesis type aliphatic polyester series macromolecular material that can degrade fully, and it is to be the polymkeric substance that the principal monomer polymerization obtains with lactic acid, and this polymkeric substance not only comprises the homopolymer of lactic acid, also comprises lactic acid and other monomeric multipolymers.Usually, the preparation method of poly(lactic acid) has three kinds, i.e. the ring-opening polymerization method of the dealcoholysis condensation method of the direct polycondensation method of lactic acid, lactate and rac-Lactide.But, because the preparation of lactic acid and the preparation of poly(lactic acid) are to carry out respectively in different manufacturers, from the building-up process that is prepared into poly(lactic acid) of lactic acid, there are many useless operations, increased the technology cost; And, in the process that with lactic acid is the raw material synthesizing polylactic acid, also there be the etching problem of lactic acid to equipment.Disclose among the Chinese patent CN1298892A and a kind ofly directly be condensed into the method for poly(lactic acid) by lactic acid, this method need consume a large amount of azeotropic solvents, but also has the problem that residues in the azeotropic solvent in the lactic acid polymer of removing.Also disclose among the Chinese patent CN1326997A and a kind ofly prepare the method for poly-lactic acid in high molecular weight by the lactic acid direct condensation, this method needs to consume a large amount of dewatering agents in preparation process, has increased the technology cost.A kind of method that is prepared poly(lactic acid) by rac-Lactide fusion/process for solid state polycondensation is disclosed among the Chinese patent CN1068011C, this method has adopted the ring-opening polymerization method of rac-Lactide, but need carry out repeatedly repolymerization behind the recrystallization to the raw material rac-Lactide, otherwise can not get high molecular weight polylactic acid, cost is higher.
Summary of the invention
The present invention is in order to solve the deficiency that prior art exists, and provides a kind of and directly prepared the method for poly(lactic acid) by fusion/process for solid state polycondensation by lactate, and this method has that cost is low, the technology characteristic of simple.The present invention is prepared according to following step: a, be raw material with the lactate or be raw material with the mixture of lactic acid and lactate, feed rare gas element, control reaction temperature pre-polymerization 8～12 hours under 100～160 ℃, the condition of pressure at 30～760mmHg obtains weight-average molecular weight and is 700～1100 lactic acid oligomer; B, will add catalyzer in the above-mentioned lactic acid oligomer, control reaction temperature melt polymerization 4～8 hours under 120～190 ℃, the condition of pressure at 1～20mmHg, reduce temperature of reaction then, control reaction temperature was cooled off under 100～110 ℃ condition 1～2 hour, obtained weight-average molecular weight and be 12000～15000 poly(lactic acid); C, last, control reaction temperature solid state polymerization 10～25 hours under 100～175 ℃, the condition of pressure at 0.5～10mmHg obtains weight-average molecular weight and is 100000～600000, fusing point is 175～180 ℃ poly-lactic acid in high molecular weight solid.The present invention has omitted the operation of the hydrolysis process and the synthesis of lactide from of lactate, has simplified technical process; Do not need to consume a large amount of dewatering agents, azeotropic solvent and recrystallization agent, saved cost; Alleviated with lactic acid be in the raw material synthesizing polylactic acid process to the problem of equipment corrosion, have the advantage that technology is simple, cost is low, corrodibility is little.
Embodiment one: present embodiment is prepared according to following step: a, be raw material with the lactate or be raw material with the mixture of lactic acid and lactate, feed rare gas element, control reaction temperature pre-polymerization 8～12 hours under 100～160 ℃, the condition of pressure at 30～760mmHg obtains weight-average molecular weight and is 700～1100 lactic acid oligomer; B, will add catalyzer in the above-mentioned lactic acid oligomer, control reaction temperature melt polymerization 4～8 hours under 120～190 ℃, the condition of pressure at 1～20mmHg, reduce temperature of reaction then, control reaction temperature was cooled off under 100～110 ℃ condition 1～2 hour, obtained weight-average molecular weight and be 12000～15000 poly(lactic acid); C, last, control reaction temperature solid state polymerization 10～25 hours under 100～175 ℃, the condition of pressure at 0.5～10mmHg obtains weight-average molecular weight and is 100000～600000, fusing point is 175～180 ℃ poly-lactic acid in high molecular weight solid.Described lactate is lactic acid and C
1～C
8The compound that forms by condensation reaction of alcohol or the compound that forms by esterification of the DL-Lactic acid ammonium salt that obtains by the food garbage fermentation and alcohol, preferably lactic acid and C
1～C
4The compound that forms by condensation reaction of alcohol; In the mixture of described lactic acid and lactate, the weight ratio of lactic acid and lactate is (1～99): (99～1); The content of described catalyzer is 0.01～6.0% of polymer monomer gross weight, and the content of preferred catalyst is 0.1～2.0% of polymer monomer gross weight; Described catalyzer is a tin class catalyzer, perhaps is zinc class catalyzer, perhaps is the binary built catalyzer of tin compound and protonic acid; Described tin class catalyzer is two hydrates of stannous octoate or tindichloride; Described zinc class catalyzer is zinc powder or zinc oxide; The binary built catalyzer of described tin compound and protonic acid is SnCl
22H
2The binary built catalyzer of O and tosic acid; Described protonic acid is boric acid, phosphoric acid or tosic acid; The weight ratio of described tin compound and protonic acid is (1～2): 1, and the weight ratio of preferred tin compound and protonic acid is 1: 1.
Embodiment two: present embodiment is prepared according to following step: a, be raw material with the lactate or be that raw material feeds rare gas element with the mixture of lactic acid and lactate, control reaction temperature pre-polymerization 8～12 hours under 140～160 ℃, the condition of pressure at 30～760mmHg obtains weight-average molecular weight and is 700～1100 lactic acid oligomer; B, will add catalyzer in the above-mentioned lactic acid oligomer, control reaction temperature melt polymerization 4～8 hours under 180 ℃, the condition of pressure at 1～20mmHg, reduce temperature of reaction then, control reaction temperature was cooled off under 105 ℃ condition 1～2 hour, obtained weight-average molecular weight and be 12000～15000 poly(lactic acid); C, last, control reaction temperature solid state polymerization under 150 ℃, the condition of pressure at 5mmHg obtain that weight-average molecular weight is 100000～300000, fusing point is 175～180 ℃ poly-lactic acid in high molecular weight solid.
Embodiment three: present embodiment is prepared according to following step: a, the 145.0g n-Butyl lactate put into the 500ml four-hole bottle that has whipping appts and nitrogen ingress pipe, feed nitrogen after 1 hour, putting into 160 ℃ of oil baths heats, under nitrogen gas stream, pressure is reduced to 200mmHg by 760mmHg stage by stage through 10 hours, obtains weight-average molecular weight and be 1000 lactic acid oligomer; B, the 50g lactic acid oligomer added be furnished with in the 250ml there-necked flask of whipping appts, add the SnCl of polymer monomer gross weight 1%
22H
2The binary built catalyzer of O and tosic acid, wherein SnCl
22H
2The weight ratio of O and tosic acid is 1: 1, be immersed in 180 ℃ of oil baths with the beaker sealing and after inserting depressurized system, polymerization is 6 hours under the pressure of stirring and 15mmHg, the oil bath crystallisation by cooling of putting into 105 ℃ then is after 1.5 hours, it is granular that it is shaped to, and obtains weight-average molecular weight and be 15000 poly(lactic acid); C, the granular poly(lactic acid) of moulding being moved in the vacuum-drying thermostat container, is that 140 ℃, pressure are under the condition of 5mmHg in temperature, and solid state polymerization 15 hours obtains weight-average molecular weight and be 150000 poly(lactic acid).
Embodiment four: what present embodiment and embodiment one were different is, a, with n-Butyl lactate 73.0g, weight concentration is that the DL-lactic acid aqueous solution 50.0g of 85-90% puts into the 500ml four-hole boiling flask that has whipping appts and nitrogen ingress pipe, feed nitrogen after 1 hour, putting into 160 ℃ of oil baths heats, the continuous adjusting was reduced to 200mmHg through 8 hours by 760mmHg with pressure under nitrogen gas stream, obtain weight-average molecular weight and be 1000 lactic acid prepolymer, other preparation processes and processing condition are with embodiment three, finally obtain weight-average molecular weight and be 200000 poly(lactic acid).
Claims (7)
1, the method that directly prepares poly(lactic acid) by fusion/process for solid state polycondensation by lactate, it is characterized in that it is prepared according to following step: a, be raw material with the lactate or be raw material with the mixture of lactic acid and lactate, feed rare gas element, control reaction temperature pre-polymerization 8～12 hours under 100～160 ℃, the condition of pressure at 30～760mmHg obtains weight-average molecular weight and is 700～1100 lactic acid oligomer; B, will add catalyzer in the above-mentioned lactic acid oligomer, control reaction temperature melt polymerization 4～8 hours under 120～190 ℃, the condition of pressure at 1～20mmHg, reduce temperature of reaction then, control reaction temperature was cooled off under 100～110 ℃ condition 1～2 hour, obtained weight-average molecular weight and be 12000～15000 poly(lactic acid); C, last, control reaction temperature solid state polymerization 10～25 hours under 100～175 ℃, the condition of pressure at 0.5～10mmHg obtains weight-average molecular weight and is 100000～600000, fusing point is 175～180 ℃ poly-lactic acid in high molecular weight solid.
2, according to claim 1ly directly prepare the method for poly(lactic acid) by lactate, it is characterized in that lactate is lactic acid and C by fusion/process for solid state polycondensation
1～C
8The compound that forms by condensation reaction of alcohol or the compound that forms by esterification of the DL-Lactic acid ammonium salt that obtains by the food garbage fermentation and alcohol; In the mixture of lactic acid and lactate, the weight ratio of lactic acid and lactate is 1～99: 99～1.
3, according to claim 2ly directly prepare the method for poly(lactic acid) by lactate, it is characterized in that lactate is lactic acid and C by fusion/process for solid state polycondensation
1～C
4The compound that forms by condensation reaction of alcohol.
4, according to claim 1ly directly prepare the method for poly(lactic acid) by lactate, it is characterized in that catalyzer is a tin class catalyzer or for zinc class catalyzer or be the binary built catalyzer of tin compound and protonic acid by fusion/process for solid state polycondensation.
5, according to claim 4ly directly prepare the method for poly(lactic acid) by lactate, it is characterized in that tin class catalyzer is two hydrates of stannous octoate or tindichloride by fusion/process for solid state polycondensation; Zinc class catalyzer is zinc powder or zinc oxide; The binary built catalyzer of tin compound and protonic acid is SnCl
22H
2The binary built catalyzer of the sharp tosic acid of O.
6, describedly directly prepare the method for poly(lactic acid) by fusion/process for solid state polycondensation by lactate according to claim 4 or 5, the weight ratio that it is characterized in that tin compound and protonic acid is 1～2: 1.
7, describedly directly prepare the method for poly(lactic acid) by fusion/process for solid state polycondensation by lactate according to claim 4 or 5, the weight ratio that it is characterized in that tin compound and protonic acid is 1: 1.
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| CN 200410013544 CN1247653C (en) | 2004-02-05 | 2004-02-05 | Process for direct preparation of poly-lactic acid from lactic acid by melt/solid phase polycondensation |
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| CN 200410013544 CN1247653C (en) | 2004-02-05 | 2004-02-05 | Process for direct preparation of poly-lactic acid from lactic acid by melt/solid phase polycondensation |
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1308367C (en) * | 2005-09-09 | 2007-04-04 | 浙江大学 | Condensation polymerization method for preparing hydroxylated acid condensation polymer |
| CN100543060C (en) * | 2006-08-03 | 2009-09-23 | 西安工程大学 | The preparation technology of poly lactic acid in use for spinning |
| CN101407576B (en) * | 2007-10-10 | 2012-10-03 | 东丽纤维研究所（中国）有限公司 | Method for preparing polylactic acid with sulfamic acid compound as catalyst |
| CN101463124B (en) * | 2007-12-21 | 2011-08-17 | 东丽纤维研究所（中国）有限公司 | Method for preparing polylactic acid with metal sulphonate as catalyst |
| CN101974146B (en) * | 2010-10-27 | 2011-12-21 | 山东大学 | Method for preparing polylactic acid by using solid acid composite lactate as catalyst |
| CN103300120B (en) * | 2013-06-25 | 2015-04-22 | 南京工业大学 | Green poultry and livestock depilating agent and preparation method thereof |
| RU2726362C1 (en) * | 2019-11-12 | 2020-07-13 | Акционерное общество "Государственный Ордена Трудового Красного Знамени научно-исследовательский институт химии и технологии элементоорганических соединений" (АО "ГНИИХТЭОС") | Method of producing polylactides |
| CN117126383A (en) * | 2022-05-18 | 2023-11-28 | 中国石油大学(华东) | Method for preparing high molecular weight polylactic acid |
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