CN101182369A - Method for preparing high-molecular-weight poly(L-lactic acid) - Google Patents
Method for preparing high-molecular-weight poly(L-lactic acid) Download PDFInfo
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- CN101182369A CN101182369A CNA2007101922463A CN200710192246A CN101182369A CN 101182369 A CN101182369 A CN 101182369A CN A2007101922463 A CNA2007101922463 A CN A2007101922463A CN 200710192246 A CN200710192246 A CN 200710192246A CN 101182369 A CN101182369 A CN 101182369A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/78—Preparation processes
- C08G63/80—Solid-state polycondensation
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Abstract
The invention provides a preparation method for a high molecular weight poly (L-lactic acid), the invention is characterized in that tartaric acid and catalyst are directly added into the L-lactic acid and reacted for polycondesation from 8 hours to 20 hours under the conditions of the temperature ranging from 150 DEG C to 200 DEG C and the pressure ranging from 100Pa to 2,500 Pa, and the prepolymer of a rough poly (L-lactic acid) which takes the appearance of colorless and transparent resin is obtained after the discharging and cooling. The cracked prepolymer is solid-state polymerized and reacted for 24 hours to 120 hours under the conditions of the temperature ranging from 120 DEG C to 170 DEG C and the pressure ranging from 100Pa to 3,000 Pa, and a branched poly (L-lactic acid) with the high molecular weight ranging from 300 thousand to 1,500 thousand is obtained or a thermosetting poly (L-lactic acid) is produced after further crosslinking formed. The product takes the appearance of almost white and powder and has the processing performance of general plastics, the product has better safety and biodegradability. The yielding rate of the technique is up to 95% of the theoretical yielding rate, the invention has the advantages of simple process, pollution free and easy industrialized production.
Description
One, technical field
The present invention relates to a kind of is central element with tartrate, prepares the method for biodegradable high-molecular-weight poly (L-lactic acid) by melt phase polycondensation-solid state polymerization.
Two, background technology
Along with the progress of science and the development of society, shortage of resources and environmental pollution have become the serious global problem of paying close attention in countries in the world.It is predicted that global petroleum resources are the enough exploitations in 50 years only, and be that the plastics industry of important source material will be seriously influenced at present with the oil, therefore, greatly develop and use the recyclability energy to become a kind of inevitable trend.The whole world produces about 1.5 hundred million tons polymkeric substance from mineral wealth such as oil every year according to statistics, about 8, the 000 ten thousand tons plastic refuse of annual simultaneously generation.Because these materials are difficult to natural degradation at nature, thereby cause waste or used plastics in natural accumulation, form so-called " white pollution ".This has not only influenced existent environment of people, and has had influence on social industry-by-industry, has caused the common concern of each side in recent years.In order to address this problem, at first be exactly the discharging of managing to reduce waste plastic, utilize novel material to replace existing petroleum product with natural degradation ability, save valuable Nonrenewable resources and alleviate the dual purpose of environmental pollution thereby reach.With the poly(lactic acid) of lactic acid preparation or lactic acid copolymer from reproducible plant resources, not only can alleviate the in short supply of Nonrenewable resources such as oil, coal, simultaneously because its degradability, also eliminate the pollution that environment is caused, will become the material of tool development prospect 21st century.Though the macromolecule poly(lactic acid) by conventional two-step approach ring-opening polymerization prepared can replace plastics to have good processing characteristics, production cost is higher relatively at present, can't extensively promote the use of.And prepare poly(lactic acid) by direct melt polycondensation, though cost is not high, the molecular weight of poly(lactic acid) is difficult to surpass 100,000.Though also can further improve molecular weight by solid state polymerization behind the melt phase polycondensation, from present disclosed data, the molecular weight of poly(lactic acid) also can only reach about 200,000.As S.I.Moon etc. done in this respect a lot of work (Polymer, 2001,, volume42, Issue11,5059-5062).The domestic patent (ZL 200410041426.8, and ZL 200410052604.7) that many this respects are also arranged all is greatly improved the molecular weight of poly(lactic acid), but its molecular weight that can reach still can't satisfy the requirement that poly(lactic acid) is used as general-purpose plastics.
All the time, scientific research personnel both domestic and external is seeking a kind ofly not only can to have improved the molecular weight of poly(lactic acid) but also the processing method that can reduce cost, wherein Kim etc. is with stannous octoate-tetramethylolmethane composite catalyst, with the L-rac-Lactide is raw material, prepares star-type polymer SPLLA (S.H.Kim, the Y-K Han of four arms, K-D Ahn, et al.[J] .Makro Chem, 1993,194:3229-3236; S.H.Kim, Y-K Han, K-D Ahn, et al.[J] .Makro Chem, 1992,193:1623-1631), be exactly a kind of method of good raising molecular weight.L-lactic acid-tetramethylolmethane star polymer that usefulness L-lactic acid such as Ma Jianhua and tetramethylolmethane are prepared by the single stage method melt phase polycondensation also has very high molecular weight (meticulous and specialty chemicals [J] .2006,14 (9): 19-22).Ioannis Arvanitoyannis etc. are central element with glycerine, with the L-rac-Lactide is the branching poly-(L-lactic acid) that raw material has synthesized three arms, highest weight about 200,000 (Ioannis Arvanitoyannis, Atsuyoshi Nakayama, Norioki Kawasaki, et al.[J] .Polymer, vol.36, No.15:2947-2956).The shortcoming of these methods is that the end group of institute's synthetic branching poly-(L-lactic acid) is identical hydroxyl, can't further improve molecular weight by solid state polymerization.
Three, summary of the invention
The present invention is the processing method that adopts melt phase polycondensation-solid state polymerization, is raw material with L-lactic acid and tartrate, prepares biodegradable high molecular weight branched poly-(L-lactic acid).
Tartrate has two carboxyls and two hydroxyls, is easy to generate by polycondensation with L-lactic acid the branching poly-(L-lactic acid) of four arms.Because hydroxyl equates with the number of carboxyl in four terminal group of the branching that generates poly-(L-lactic acid), can further improve molecular weight by solid state polymerization, can synthesize molecular weight and surpass 1,000,000 branching poly-(L-lactic acid).The raising of molecular weight makes the physical strength of product strengthen; The molecular structure of branching makes the melting viscosity of product reduce, and helps melt-processed, has also improved the fragility of product simultaneously.Because tartrate is the four-functional group molecule, crosslinking reaction takes place when consumption is too much, generate thermoset poly-(L-lactic acid); When the tartrate consumption is suitable, can generate high molecular weight branched poly-(L-lactic acid) by polycondensation-solid state polymerization.Also find to use tartrate at present, prepare high molecular weight branched poly-(L-lactic acid) and the crosslinked research report that gathers (L-lactic acid) by carrying out solid state polymerization behind the melt phase polycondensation again.Because tartrate is foodstuff additive, so poly-(the L-lactic acid) that generates has good security and biodegradability.
Characteristics of the present invention are to have following steps:
(1) melt phase polycondensation: with L-lactic acid, tartrate is raw material, under catalyst action, generates poly-(L-lactic acid) prepolymer of branching through the dehydration polycondensation.
(2) solid state polymerization: the prepolymer powder of pulverizing is placed in vacuum drying oven or the rotary type vacuum reactor, carry out solid state polymerization under the vacuum condition, make high-molecular-weight poly (L-lactic acid).
Advantage of the present invention is to need not special conversion unit, uses cheap L-lactic acid and tartrate to be raw material, and catalyst levels is few, need not purified product with an organic solvent, thereby production cost is lower.Poly-(L-lactic acid) molecular weight of gained can reach 30～1,500,000, has higher physical strength and good processing properties.
Implementation method is as follows:
1. melt phase polycondensation: L-lactic acid and an amount of tartrate are added in the reactor, under agitation drop into the catalyzer of proportional.Heating up starts vacuum system simultaneously, at 110～140 ℃, and pressure 20,000～50, under the 000Pa, negative pressure is sloughed free-water and a small amount of reaction water.When going out water speed and obviously reduce, rising temperature of reaction, gas clean-up simultaneously.When temperature rises to 150～200 ℃, keep-up pressure 100～2,500Pa reacted 8～20 hours.Emit material, cool off to such an extent that crude product gathers (L-lactic acid) prepolymer, outward appearance is the colourless transparent resin shape, and molecular weight is 10,000～50,000.
The polycondensation catalyst system therefor is mineral acids such as sulfuric acid, phosphoric acid; Tin protoxide, tin protochloride, tin tetrachloride etc.Catalyst levels is 0.03～0.5% of a L-lactic acid.
2. solid state polymerization: prepolymer is ground into 20～200 order fine particles, places vacuum drying oven or other rotary type vacuum reactor to carry out solid state polymerization.Temperature is controlled at 120～170 ℃, and pressure is 100～3, and 000Pa reacted 24～120 hours, can get molecular weight and be 30～1,500,000 high-molecular weight branching poly-(L-lactic acid).
The catalyst levels that the present invention uses is few, catalytic activity is high, speed is fast, has shortened the production cycle greatly, helps improving industrial production efficient, reduces cost, and the molecular weight of gained poly-(L-lactic acid) is very big simultaneously.Residual catalyzer used water or diluted acid extracting and separating in the product, waste water can be used as non-domestic water and use after neutralization, can not produce environment and pollute.
Four, embodiment
Embodiment 1:
In being equipped with the 500ml there-necked flask of agitator, distillation column, condenser, thermometer and vacuum distillation apparatus, drop into 500gL-lactic acid (concentration 90.0%, optical purity 97.6%), 15.2g tartrate, 0.48ml sulfuric acid (98%).Under evenly stirring, at the uniform velocity heat up from room temperature, simultaneously decompression dehydration.After three hours, temperature is 140 ℃, and pressure is 3, during 500Pa, keeps this state 1 hour.When again temperature being raised to 170 ℃, reduce pressure 2,000Pa kept this state 8 hours, material is poured out cooling after, can obtain being close to poly-(L-lactic acid) prepolymer 368.7g of colourless transparent resin shape, be 16,000 through GPC test molecule amount.Through powder essence, mistake 100 mesh sieves, fine particle places Stainless Steel Disc, spreads out the thickness into about 2 centimetres, puts into vacuum drying oven and carries out solid state polymerization.Pressure is 1 in the vacuum drying oven, 200Pa, and temperature is 140 ℃, reacts 24 hours, gets poly-(the L-lactic acid) of crosslinked shape, gel fraction is 70%.
Embodiment 2:
Experimental installation and operation are with embodiment 1,500gL-lactic acid (concentration 90.0%, optical purity 97.6%), 3.77g tartrate, 0.24ml sulfuric acid (98%), the reaction times that temperature is raised to after 190 ℃ is 12 hours, the molecular weight of poly-(L-lactic acid) prepolymer of gained is 22,400.During solid state polymerization, pressure is 1 in the vacuum drying oven, 500Pa, and temperature is 160 ℃, and polymerization time is 72 hours, gets poly-(the L-lactic acid) of crosslinked shape, and gel fraction is 52%.
Embodiment 3:
Experimental installation and operation are with embodiment 1,500gL-lactic acid (concentration 90.0%, optical purity 97.6%), 3.77g tartrate, 0.12ml sulfuric acid (98%), the reaction times that temperature is raised to after 180 ℃ is 16 hours, the molecular weight of poly-(L-lactic acid) prepolymer of gained is 20,300.During solid state polymerization, pressure is 1 in the vacuum drying oven, 500Pa, and temperature is 150 ℃, and polymerization time is 48 hours, gets branching poly-(L-lactic acid), and molecular weight is 348,000.
Embodiment 4:
Experimental installation and operation are with embodiment 1,500gL-lactic acid (concentration 90.0%, optical purity 97.6%), 2.52g tartrate, 0.92g tin protochloride (98%), the reaction times that temperature is raised to after 180 ℃ is 18 hours, poly-(L-lactic acid) prepolymer molecular weight of gained is 38,200.During solid state polymerization, pressure is 1 in the vacuum drying oven, 200Pa, and temperature is 155 ℃, and polymerization time is 72 hours, gets branching poly-(L-lactic acid), and molecular weight is 735,000.
Embodiment 5:
Experimental installation and operation are with embodiment 1,500gL-lactic acid (concentration 90.0%, optical purity 97.6%), 1.91g tartrate, 1.84g tin protochloride (98%), the reaction times that temperature is raised to after 180 ℃ is 20 hours, poly-(L-lactic acid) prepolymer molecular weight of gained is 43,500.During solid state polymerization, pressure is 1 in the vacuum drying oven, 200Pa, and temperature is 160 ℃, and polymerization time is 96 hours, gets branching poly-(L-lactic acid), and molecular weight is 1,076,000.
Embodiment 6:
Experimental installation and operation are with embodiment 1,500gL-lactic acid (concentration 90.0%, optical purity 97.6%), 0.96g tartrate, 1.38g tin protochloride (98%), the reaction times that temperature is raised to after 190 ℃ is 20 hours, poly-(L-lactic acid) prepolymer molecular weight of gained is 47,300.During solid state polymerization, pressure is 1 in the vacuum drying oven, 500Pa, and temperature is 150 ℃, and polymerization time is 120 hours, gets branching poly-(L-lactic acid), and molecular weight is 863,000.
Embodiment 7:
Experimental installation and operation are with embodiment 1,500gL-lactic acid (concentration 90.0%, optical purity 97.6%), 0.85g tartrate, 1.82g stannous octoate, the reaction times that temperature is raised to after 180 ℃ is 18 hours, poly-(L-lactic acid) prepolymer molecular weight of gained is 42,400.During solid state polymerization, pressure is 1 in the vacuum drying oven, 500Pa, and temperature is 155 ℃, and polymerization time is 72 hours, gets branching poly-(L-lactic acid), and molecular weight is 378,000.
Embodiment 8:
Experimental installation and operation are with embodiment 1,500gL-lactic acid (concentration 90.0%, optical purity 97.6%), 1.52g tartrate, 0.91g stannous octoate, the reaction times that temperature is raised to after 180 ℃ is 16 hours, poly-(L-lactic acid) prepolymer molecular weight of gained is 32,700.During solid state polymerization, pressure is 1 in the vacuum drying oven, 200Pa, and temperature is 160 ℃, and polymerization time is 96 hours, must gather branching (L-lactic acid), and molecular weight is 485,000.
Embodiment 9:
Experimental installation and operation are with embodiment 1,500gL-lactic acid (concentration 90.0%, optical purity 97.6%), 2.53g tartrate, 1.38g tin protochloride (98%), the reaction times that temperature is raised to after 180 ℃ is 20 hours, poly-(L-lactic acid) prepolymer molecular weight of gained is 43,800.Solid state polymerization reactor is a rotatory evaporator, and rotating speed is 10 rev/mins, and oil bath temperature is 160 ℃, and pressure is 1, and 800Pa, polymerization time are 120 hours, gets branching poly-(L-lactic acid), and molecular weight is 1,408,000.
Embodiment 10:
Experimental installation and the operation with embodiment 1,500gL-lactic acid (concentration 90.0%, optical purity 97.6%), 1.52g tartrate, 0.24ml sulfuric acid (98%).The reaction times that temperature is raised to after 175 ℃ is 18 hours, and poly-(L-lactic acid) prepolymer molecular weight of gained is 35,200.Solid state polymerization reactor is a rotatory evaporator, and rotating speed is 15 rev/mins, and oil bath temperature is 160 ℃, and pressure is 1, and 600Pa, polymerization time are 108 hours, gets branching poly-(L-lactic acid), and molecular weight is 1,267,000.
Claims (6)
1. the preparation method of a high-molecular-weight poly (L-lactic acid), its feature may further comprise the steps:
(1) melt phase polycondensation: with raw material L-lactic acid (aqueous solution of content more than 85%), tartrate, catalyst mix, direct melt polycondensation after the negative pressure dehydration, in 150～200 ℃, 100～2, under the 500Pa condition, reacted 8～20 hours, molecular weight is poly-(L-lactic acid) prepolymer of 10,000～50,000.According to the difference of tartrate consumption, this prepolymer can be used as the raw material of next step solid state polymerization or the raw material of further crosslinked generation thermoset poly-(L-lactic acid).
(2) solid state polymerization: gained prepolymer in the step (1) is ground into 20～200 order fine particles, places vacuum drying oven, or put into other rotation vacuum reactor and carry out solid state polymerization.Solid phase polymerization temperature is 120～170 ℃, and vacuum tightness is 100～3,000Pa, and the reaction times is 24～120 hours, can get molecular weight and be 30～1,500,000 high-molecular weight branching poly-(L-lactic acid).
2. the preparation method of high-molecular weight according to claim 1 poly-(L-lactic acid), it is characterized in that: in described step (1), the mol ratio of tartrate and L-lactic acid is 1: 10～1: 1,000.Catalyst levels is 0.03%～0.5% of a L-lactic acid quality.
3. the preparation method of high-molecular weight according to claim 1 poly-(L-lactic acid), it is characterized in that: in the step (1), as the tartrate of further crosslinked generation thermoset poly-(L-lactic acid) and the mol ratio of L-lactic acid is 1: 10～1: 300, and preferred proportion is 1: 30～1: 200.
4. the preparation method of high-molecular-weight poly according to claim 1 (L-lactic acid), it is characterized in that: in the step (1), as the tartrate of further solid state polymerization generation high molecular weight branched poly-(L-lactic acid) and the mol ratio of L-lactic acid is 1: 200～1: 1,000, preferred proportion is 1: 200～1: 500.
5. the preparation method of high-molecular weight according to claim 1 poly-(L-lactic acid), it is characterized in that: catalyst system therefor can be mineral acids such as sulfuric acid, phosphoric acid; Perhaps tindichloride, tin tetrachloride, tin protoxide etc.
6. the preparation method of high-molecular weight according to claim 1 poly-(L-lactic acid), it is characterized in that: in described step (2), solid phase polymerization temperature preferably is controlled at 140～160 ℃, and pressure is 500～2,000Pa.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007101922463A CN101182369A (en) | 2007-12-24 | 2007-12-24 | Method for preparing high-molecular-weight poly(L-lactic acid) |
| PCT/CN2008/073518 WO2009082924A1 (en) | 2007-12-24 | 2008-12-16 | A process for preparing high molecular weight poly (l-lactic acid) |
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| CNA2007101922463A CN101182369A (en) | 2007-12-24 | 2007-12-24 | Method for preparing high-molecular-weight poly(L-lactic acid) |
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| CN101182369A true CN101182369A (en) | 2008-05-21 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009082924A1 (en) * | 2007-12-24 | 2009-07-09 | Anhui Zhongren Science & Technology Co., Ltd. | A process for preparing high molecular weight poly (l-lactic acid) |
| CN101921466B (en) * | 2009-06-10 | 2012-10-24 | 东丽纤维研究所（中国）有限公司 | Polylactic acid composition containing sulfuric acid compounds and method for preparing polylactic acid by using sulfuric acid as catalyst |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11240941A (en) * | 1998-02-26 | 1999-09-07 | Nishikawa Rubber Co Ltd | Production of hydrolyzable and biodegradable polyhydroxycarboxylic acid copolymer resin |
| CN1331912C (en) * | 2004-07-07 | 2007-08-15 | 同济大学 | Method of preparing high molecular weight polylactic acid using solid phase polymerization |
| CN1295264C (en) * | 2004-07-15 | 2007-01-17 | 合肥工业大学 | Method for preparing high molecular weight poly-L-lactic acid by melt polycondensation-solid phase polymerization |
| CN101182369A (en) * | 2007-12-24 | 2008-05-21 | 安徽中人科技有限责任公司 | Method for preparing high-molecular-weight poly(L-lactic acid) |
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2007
- 2007-12-24 CN CNA2007101922463A patent/CN101182369A/en active Pending
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2008
- 2008-12-16 WO PCT/CN2008/073518 patent/WO2009082924A1/en active Application Filing
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009082924A1 (en) * | 2007-12-24 | 2009-07-09 | Anhui Zhongren Science & Technology Co., Ltd. | A process for preparing high molecular weight poly (l-lactic acid) |
| CN101921466B (en) * | 2009-06-10 | 2012-10-24 | 东丽纤维研究所（中国）有限公司 | Polylactic acid composition containing sulfuric acid compounds and method for preparing polylactic acid by using sulfuric acid as catalyst |
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| WO2009082924A1 (en) | 2009-07-09 |
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