CN1887931A - Prepn of high molecular weight polylactic acid - Google Patents
Prepn of high molecular weight polylactic acid Download PDFInfo
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- CN1887931A CN1887931A CN 200610029505 CN200610029505A CN1887931A CN 1887931 A CN1887931 A CN 1887931A CN 200610029505 CN200610029505 CN 200610029505 CN 200610029505 A CN200610029505 A CN 200610029505A CN 1887931 A CN1887931 A CN 1887931A
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Abstract
The preparation process of high molecular weight polylactic acid includes the following steps: 1. decompression reflux evaporation to eliminate water from lactic acid material; 2. esterifying the dewatered lactic acid in inert gas atmosphere; 3. pre-condensating the esterified product in the presence of catalyst through gradual decompression; and 4. low vacuum polycondensing the pre-polymer through gradual decompression and in the presence of catalyst to obtain high molecular weight polylactic acid. The present invention adopts direct smelting polycondensation, and has simple production process, simple production apparatus, low cost and easy realization in industrial production.
Description
Technical field
The present invention relates to a kind of preparation method of organic polymer material, particularly relate to a kind of preparation method of high molecular weight polylactic acid.
Background technology
Poly(lactic acid) is a kind of reproducible biodegradable material, has excellent biological compatibility.Because it is nontoxic, degradable, characteristics such as can regenerate, and meets the requirement of environmental protection and Sustainable development, thereby more and more receives investigation of materials person and business people's concern.The second-order transition temperature of high molecular weight polylactic acid is about 60 ℃, fusing point is about 180 ℃, be and polystyrene (PS), the polyester close thermal plasticity high polymers of physical and mechanical properties such as (PET), its processing characteristics is good, can utilize that general device of plastic processing is extruded, injection, blow molding, also can with general-purpose plastics blend or copolymerization, in addition, poly(lactic acid) also can be spun into fiber by melt spinning method, and its fabric crease resistance is strong, good permeability, comfortable and easy to wear.Therefore, as a kind of new bio degradable material, poly(lactic acid) has very wide application prospect.
Because poly(lactic acid) application in many aspects all requires high molecular, in recent years, the technology of preparing of low-cost poly-lactic acid in high molecular weight has become the focus of research.Use the more method for preparing poly-lactic acid in high molecular weight at present and comprise direct polycondensation method, ring-opening polymerization method, copolymerization method and chain extension method.Industrial main employing ring-opening polymerization method is made rac-Lactide with lactic acid earlier, again by the rac-Lactide ring-opening polymerization.U.S. Cargill-Dow company utilizes this method to build up 140,000 tons/year industrial production line, and has applied for numerous patents.The disadvantage of this method is the rac-Lactide that needs preparation polymerization-grade purity, complex process, and cost is higher relatively.H.Ajioka etc. are at Bull.Chem.Soc.Jpn.1995,68:2125 has reported that employing solution polymerization direct method obtains high molecular weight polylactic acid, but owing to need to use high boiling solvent azeotropic, operation is comparatively complicated, condition control is more strict, during polymerization product purifying solvent be difficult for Ex-all with and have a solvent recuperation problem.Moon S I etc. are at Polym SciA:Polym Chem2000,38:1673 ~ 1679 have been reported by the lactic acid direct melt polycondensation, with protonic acid activatory Bivalent Tin compound is catalyzer, obtained high molecular weight polylactic acid (Mw=100000), and do not have serious racemization and Yan look to change, yet the use meeting serious environment pollution of a large amount of strong protonic acids and the strong acid in etching apparatus and the product are difficult for removing.
Summary of the invention
Technical problem to be solved by this invention provides a kind of preparation method of high molecular weight polylactic acid, to remedy the deficiencies in the prior art or defective, meets the demands of production and living.
In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is: a kind of preparation method of high molecular weight polylactic acid comprises the steps:
(1) dehydration: the method for employing reduced-pressure backflow evaporation is removed the moisture in the lactic raw material, and wherein, dehydration temperaturre is 70 ℃～150 ℃, and vacuum tightness is 300～10000Pa, and dewatering time is 1～15 hour;
(2) esterification: the lactic acid after dehydration, under atmosphere of inert gases, add catalyzer and carry out esterification, wherein, esterification temperature is 100～220 ℃, the reaction times is 1～50 hour;
(3) progressively decompression: carboxylate in the presence of catalyzer, at 100～220 ℃, will be reacted vacuum and progressively is decompressed to 10～1000Pa and carries out precondensation in 1～50 hour;
(4) polycondensation: in the presence of catalyzer, being raw material with the lactic acid polymer that obtains that progressively reduces pressure, is 100～220 ℃ in temperature, reacts under the low vacuum state of 10～1000Pa and carries out the rough vacuum polycondensation in 1～100 hour, makes high molecular weight polylactic acid.
As optimized technical scheme: described catalyzer is one or more in metal, metal oxide or the organometallics of II, III, IV and V family in the periodic table of chemical element, and catalyst consumption is 0.1～10wt% of lactic acid weight.
Described catalyzer is one or more in Bivalent Tin compound or the tetravalent titanium compound, and specifically catalyzer is one or more in tin protochloride, stannous octoate, titanium tetrachloride or the tetrabutyl titanate; Described lactic acid is L-lactic acid; Described rare gas element is a nitrogen.
The invention has the beneficial effects as follows: adopt the direct melt polycondensation method, production technique, equipment are simple, and cost is low, is easy to realize the industrialization continuous production.
Description of drawings
The nmr spectrum of the poly(lactic acid) of Fig. 1 embodiment of the invention 1 preparation
The infrared spectrum of the poly(lactic acid) of Fig. 2 embodiment of the invention 1 preparation
Embodiment
Below in conjunction with specific embodiment the present invention is further elaborated.
Embodiment 1:
With concentration is that 90% L-lactic acid joins in the three-necked flask that has whipping appts, slowly is heated to 100 ℃, is decompressed to 1000Pa, stirs dehydration 3 hours; Remove vacuum then, at nitrogen atmosphere temperature is raised to 160 ℃, the tin protochloride that adds L-lactic acid weight 1wt% reacted 7 hours as catalyzer; In 7 hours, progressively be decompressed to 200Pa then, continue reaction 30 hours.Fig. 1 is the nmr spectrum of the poly(lactic acid) of present embodiment preparation, and Fig. 2 is its infrared spectrum.This spectrogram has proved the structure of synthesizing polylactic acid, and recording the weight-average molecular weight that makes poly(lactic acid) by viscosimetry is 11.6 ten thousand.
Embodiment 2:
With concentration is that 90% L-lactic acid joins in the three-necked flask that has whipping appts, slowly is heated to 150 ℃, is decompressed to 10000Pa, stirs dehydration 15 hours; Remove vacuum then, at nitrogen atmosphere temperature is raised to 220 ℃, the tetrabutyl titanate that adds L-lactic acid weight 4wt% reacted 1 hour as catalyzer; In 50 hours, progressively be decompressed to 1000Pa then, continue reaction 30hr.Recording the weight-average molecular weight that makes poly(lactic acid) by viscosimetry is 9.1 ten thousand.
Embodiment 3:
With concentration is that 90% L-lactic acid joins in the three-necked flask that has whipping appts, slowly is heated to 70 ℃, is decompressed to 300Pa, stirs dehydration 1 hour; Remove vacuum then, at nitrogen atmosphere temperature is raised to 100 ℃, the tetrabutyl titanate that adds L-lactic acid weight 5wt% reacted 50 hours as catalyzer; In 1 hour, progressively be decompressed to 10Pa then, continue reaction 40hr.Recording the weight-average molecular weight that makes poly(lactic acid) by viscosimetry is 120,000.
Embodiment 4:
With concentration is that 90% L-lactic acid joins in the three-necked flask that has whipping appts, slowly be heated to 120 ℃, be decompressed to 500Pa, stir dehydration 3hr, remove vacuum then, temperature is raised to 180 ℃ at nitrogen atmosphere, the tin protochloride that adds L-lactic acid weight 7wt% is as catalyzer, reaction 5hr progressively was decompressed to 300Pa then in 7 hours, continue reaction 20hr.Recording the weight-average molecular weight that makes poly(lactic acid) by viscosimetry is 8.9 ten thousand.
Claims (6)
1, a kind of preparation method of high molecular weight polylactic acid is characterized in that, comprises the steps:
(1) dehydration: the method for employing reduced-pressure backflow evaporation is removed the moisture in the lactic raw material, and wherein, dehydration temperaturre is 70 ℃～150 ℃, and vacuum tightness is 300～10000Pa, and dewatering time is 1～15 hour;
(2) esterification: the lactic acid after dehydration, under atmosphere of inert gases, add catalyzer and carry out esterification, wherein, esterification temperature is 100～220 ℃, the reaction times is 1～50 hour;
(3) progressively decompression: carboxylate in the presence of catalyzer, at 100～220 ℃, will be reacted vacuum and progressively is decompressed to 10～1000Pa and carries out precondensation in 1～50 hour;
(4) polycondensation: in the presence of catalyzer, being raw material with the lactic acid polymer that obtains that progressively reduces pressure, is 100～220 ℃ in temperature, reacts under the low vacuum state of 10～1000Pa and carries out the rough vacuum polycondensation in 1～100 hour, makes high molecular weight polylactic acid.
2, preparation method according to claim 1, it is characterized in that, described catalyzer is one or more in metal, metal oxide or the organometallics of II, III, IV and V family in the periodic table of chemical element, and catalyst consumption is 0.1～10wt% of lactic acid weight.
3, preparation method according to claim 1 and 2 is characterized in that, described catalyzer is one or more in Bivalent Tin compound or the tetravalent titanium compound.
4, preparation method according to claim 3 is characterized in that, described catalyzer is one or more in tin protochloride, stannous octoate, titanium tetrachloride or the tetrabutyl titanate.
5, preparation method according to claim 1 is characterized in that, described lactic acid is L-lactic acid.
6, preparation method according to claim 1 is characterized in that, described rare gas element is a nitrogen.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200610029505 CN1887931A (en) | 2006-07-28 | 2006-07-28 | Prepn of high molecular weight polylactic acid |
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| CN 200610029505 CN1887931A (en) | 2006-07-28 | 2006-07-28 | Prepn of high molecular weight polylactic acid |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101302283B (en) * | 2007-05-10 | 2011-11-09 | 东丽纤维研究所（中国）有限公司 | Rare earth compound-containing polylactic acid and preparation thereof |
| CN110972753A (en) * | 2020-01-10 | 2020-04-10 | 湖南文理学院 | Agricultural light conversion spray liquid and preparation method thereof |
-
2006
- 2006-07-28 CN CN 200610029505 patent/CN1887931A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101302283B (en) * | 2007-05-10 | 2011-11-09 | 东丽纤维研究所（中国）有限公司 | Rare earth compound-containing polylactic acid and preparation thereof |
| CN110972753A (en) * | 2020-01-10 | 2020-04-10 | 湖南文理学院 | Agricultural light conversion spray liquid and preparation method thereof |
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