CN1557854A - Process for preparing poly-lacti acid - Google Patents
Process for preparing poly-lacti acid Download PDFInfo
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- CN1557854A CN1557854A CNA2004100216799A CN200410021679A CN1557854A CN 1557854 A CN1557854 A CN 1557854A CN A2004100216799 A CNA2004100216799 A CN A2004100216799A CN 200410021679 A CN200410021679 A CN 200410021679A CN 1557854 A CN1557854 A CN 1557854A
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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
That the present invention relates to is a kind of preparation method of poly(lactic acid), specifically be to be reactor with the double screw rod extruder, make process disposable finishing in extruder such as the deviating from of polyreaction, monomer and byproduct, molecular weight control, product purification, and obtain the high molecular weight polylactic acid product.
Background technology
Poly(lactic acid) is an a kind of family macromolecule polymkeric substance that is monomer by chemosynthesis with the microbial fermentation product, have nontoxic, nonirritant and good biocompatibility, biodegradable absorption, intensity height, plasticity-is good, it is current one of the maximum synthesized degradable polymkeric substance of medically using, on health care, can be used as operating sutures, orthopaedics material, artificial skin and medicinal slow release agent etc., also have in fields such as agricultural, fishery, forestry, foodstuffs industry, weaving, packing and disposable products widely and use.
Currently reported poly(lactic acid) synthetic method mainly contains two kinds of direct method and indirect methods, promptly is the direct method of condensing of raw material with lactic acid and is the ring-opening polymerization method of raw material with the rac-Lactide.The former carries out polycondensation by the direct dehydration of lactic acid molecules to obtain poly(lactic acid), advantage is the productive rate height, technical process is short, but requirement height (more than 95%) to lactic raw material purity, and be difficult to make high molecular weight polylactic acid, the molecular weight of product has only several thousand, belongs to a kind of oligopolymer, and what obtain after the improvement technology also only is molecular weight polymkeric substance up to ten thousand.The latter's ring-opening polymerization method belongs to indirect synthesis technique, is that the oligopolymer rac-Lactide with lactic acid is a raw material, obtains poly(lactic acid) by ring-opening polymerization under antimony, tin class catalyst action.This method can improve the relative molecular weight of poly(lactic acid), can obtain the poly(lactic acid) of higher molecular weight, molecular weight generally can be more than 100,000, and less demanding to material purity, even available tankage and waste material, but the weak point of this method is a rac-Lactide must could polymerization generate poly-lactic acid in high molecular weight through purifying, and facility investment is big, the technical requirements height, can't carry out serialization production, and catalyst residue amount height in the product.As:
The Chinese patent of publication number CN 1326997A discloses the method that a kind of direct condensation prepares poly-lactic acid in high molecular weight, lactic acid or low molecular weight and dewatering agent are placed airtight polymeric kettle together, get rid of the oxygen in the polymeric kettle, under 60～300 ℃ temperature, reacted 0.1～100 hour, and can obtain molecular-weight average and be 10,000～500,000 poly(lactic acid).
The Chinese patent of publication number CN 1430676A has been reported and has a kind ofly been obtained lactic acid by fermentation by the starch agricultural-food, then by ultrafiltration, nanofiltration and/or electrodialysis with the lactic acid ultrapurification, and lactic acid concentrated and produces prepolymer, form two lactides and purify through the cyclisation depolymerization again, at last with the preparation method of two lactide ring-opening polymerizations.
The Chinese patent of publication number CN 1369490A then provides a kind of manufacture method of lactide, the DL-Lactic acid ammonium salt synthesizing lactic acid ester that elder generation is obtained by lactic fermentation, in the presence of the catalyzer beyond the monobutyl tin, described lactate is carried out polycondensation then, synthetic mean molecule quantity not sufficient 15,000 poly(lactic acid) (lactic acid prepolymer), make described poly(lactic acid) depolymerization again, obtain lactide.
Above-mentioned two kinds of preparation methods weak point technically is at present, make the complex manufacturing of poly(lactic acid), long flow path is to the ingredient requirement height, facility investment is big, the technical requirements height can't carry out serialization production, so the production cost height, the poly(lactic acid) cost that obtains is higher than common plastic material far away, thereby only be used in medical treatment and some high-grade packaging industries, other Application for Field is almost blank, is seriously to restrict the important factor that poly(lactic acid) is promoted and used.
Summary of the invention
According to above-mentioned situation, the present invention will provide a kind of novel method for preparing poly(lactic acid), make it can realize making process disposable finishing in double screw rod extruder such as the deviating from of polyreaction, monomer and byproduct, molecular weight control, product purification, and obtain the high molecular weight polylactic acid product.
The basic preparation method of poly(lactic acid) of the present invention, be that oligopolymer or lactide dimer with lactic acid is raw material, under initiator and catalyst action, with double screw rod extruder as reactor, make polyreaction, deviating from of monomer and byproduct, molecular weight control, technologies such as product purification are being mediated disposable finishing in the extruder in the same way, obtain molecular weight at last and reach 80,000-200,000 poly-lactic acid in high molecular weight, building-up reactions can be finished in 5-30 branch clock time, accelerated the production cycle, increase substantially production efficiency, effectively reduce the production cost of poly(lactic acid).
The present invention adopts double screw rod extruder as reactor, and made full use of the unique function that is different from traditional reactor that polyreaction processing aspect is had: one is polymerization and response function, similar mixed reactor traditionally.The inventive method replaces original tank reactor with double screw rod extruder just, utilize in the forcing machine combination of different spiral shell pieces can produce the characteristics of multiple function and mixing reaction conditions is controlled, make starting monomer in the process of extruding by forcing machine, finish polyreaction, obtain the high-molecular weight material.Thereby make more simple and direct to the preparation of poly-lactic acid in high molecular weight, efficient and economy and facility.Its two, be its devolatilization function.The purpose of devolatilization is that volatile matter such as unreacted monomer and solvent are removed from polymkeric substance.Because the synthetic of poly(lactic acid) is a condensation course that constantly produces water, in order to impel molecular balance to move right, make reaction continue to carry out and obtain high molecular weight polylactic acid and product is carried out purifying, remove so water that produces in the building-up process and unreacted monomer all must in time be waved.The first part of devolatilization process is that the diffustivity quality is transmitted (volatiles diffuses to polymkeric substance-steam interface), and second section is convection properties amount transmission (volatiles is in the interface evaporation and be removed), can be easily 80%～90% fugitive constituent be removed.Along with the reduction of volatile content, the viscosity of polymer system increases gradually, the mass transfer of system, the gradually difficulty of conducting heat.Therefore bubble devolatilization and diffusion devolatilization need condition of high vacuum degree and be furnished with mechanical stirring and the condition of temperature under operate.Because forcing machine has effects such as good conveying, heat transfer, mixing, dispersion and Surface Renewal, so devolatilization is very easy to carry out, operating restraint is very big.Especially low in volatiles concentration, the material viscosity height (still has good devolatilization effect under 0.1～5.0kPa.s) the condition, can on same machine, realize simultaneously multiple functions such as work such as the removing of stirring, conveying, monomer and byproduct, product purification and extruding pelletization again, thereby simplified polyreaction aftertreatment flow process widely, helped reducing production costs significantly.Its three, be the controlled function that can have to molecular weight.The main size that adopts stopper to regulate molecular weight in the common polymer production as poly synthetic, is to inject certain molecular-weight adjusting with reaction terminating at last stage reaction.This mode required time is longer.The main mode of molecular weight regulator and mechanical shearing that adopts is finished jointly in the production of poly(lactic acid), and wherein the use of molecular weight regulator is main mode.This regulative mode is subjected to the influence of H2 molecular diffusion ability size, so the mixed ability of the viscosity of material, processing temperature and screw rod is an important parameters very.In addition, can also carry out the auxiliary adjustment mode, the polylactic acid molecule chain is ruptured under the mechanical shearing effect, reach the purpose of control molecular weight size by the rotating speed of adjusting screw(rod).
Consisting of of the raw mix that the above-mentioned synthetic method of the present invention is used:
Lactic acid performed polymer 95-99 weight part,
Catalyzer 0.001-3 weight part,
Stablizer 0.001-3 weight part,
Wherein, said lactic acid performed polymer is that molecular weight is at least a in the lactic acid oligomer of 1000-5000 or the lactic acid dimer, and wherein this lactic acid dimer can be L-L rac-Lactide, any in D-D rac-Lactide or the L-D rac-Lactide; Catalyzer is the muriate of tin or in the alkylate any, for example can be in monobutyl tin, diethyl caproic acid Bivalent Tin or their muriate a kind of; Stablizer is any in phosphorous acid or the triphenyl phosphorus.
The raw mix of above-mentioned composition form is injected the twin screw extruder of length-to-diameter ratio 〉=40 of having done corresponding preheating, the setting of each temperature of reaction section is followed successively by 130 ℃-170 ℃, 150 ℃-190 ℃, 160 ℃-185 ℃ and 125 ℃-150 ℃, head pressure is 1-5Mpa, engine speed is 50-500 rev/min, the 3rd, in the four temperature of reaction sections respectively the vacuum tightness with 0.005-0.06Mpa pressure be connected with the devolatilization device, and inject the hydrogen of 0.0001-0.01 weight part continuously as molecular weight regulator at the 3rd temperature section later stage or the 4th temperature section initial stage, the raw mix that injects is carried out successive mediate extrusion reaction, reaction times 5-30 minute.
When carrying out above-mentioned extrusion reaction, for used double screw rod extruder, can adopt the double screw rod extruder of engagement type in the same way or incorgruous engagement type, because the shearing action and the melting effect of engagement type double screw rod extruder all are better than incorgruous engagement type double screw rod extruder in the same way, so the engagement type double screw rod extruder serves as preferred to use in the same way, and supplies to implement reference as embodiment.
The twin screw extruder of constantly making the rotation ahead running is a kind of dynamic response device, and mixture is carrying out mixing and building-up reactions poly(lactic acid) in the process that the screw rod that is combined promotes to move simultaneously.Therefore, the screw combinations in the twin screw extruder can be adjusted according to demand, to satisfy the requirement to reaction conditions and time control.And the length-to-diameter ratio that changes screw rod can produce remarkable influence to the mixing of material and reaction.Generally speaking, the length-to-diameter ratio of twin screw extruder is big more, and material carries out the mixing reaction times in forcing machine corresponding long more, react also abundant more fully, help improving and extrude effect.Length-to-diameter ratio hour though can not influence the carrying out of reaction, because length-to-diameter ratio is too small to cause the reaction times shorter relatively, and makes the artificial controlled relatively poor of technological process, the obvious efficient of influence reaction, and may make the degree of purity of production reduction.The length of present known twin screw extruder can reach 60/1.Test shows, synthetic to poly(lactic acid) of the present invention reacts in length-to-diameter ratio is at least 40 twin screw extruder, promptly can obtain comparatively ideal effect, is good with the twin screw extruder that adopts length-to-diameter ratio＞50 especially wherein.
Since the screw rod in the double screw rod extruder be by different spiral shell block elements in order series combination form, with finish conveying respectively to reaction mass, shear mediate, corresponding function such as mixing, loopback material, and by adjustment and control and different combinations to differential responses stage unit respective reaction parameter, suitable reaction environment and reaction conditions is provided, realize to the reaction mass that injects forcing machine conveying, shear mixing and residence time of material is controlled.For example, in above-mentioned Reaction conditions range, improve temperature and then can make speed of response fast.By general control principle, in the transportation section and head latter end temperature can be lower, the temperature in mixing district can be higher; Gas clean-up will help molecular balance and move to direction of polymerization, obtain a large amount of poly(lactic acid), but vacuum tightness exceeds limit returning charge take place easily again then, and promptly material can spill from vacuum hole; Adjust the rotating speed of main frame and can control the residence time and the output of material in forcing machine, rotating speed is fast, and then short being unfavorable for of the residence time reacts, but the output height; Otherwise then the residence time long, but output is reduced relatively.
Adopt the remarkable advantage of method for preparing poly(lactic acid) of the present invention to show to make technological operation disposable finishing in double screw rod extruder such as the deviating from of polyreaction, monomer and byproduct, molecular weight control, product purification, obtain high molecular weight polylactic acid at last, and production process is simple and direct, and production cost reduces significantly.Compare with traditional synthesis mode, the production cycle shortened to about 10-30 minute by original 10-20 hour, had saved lot of manpower and material resources.Test-results shows, the comparable existing poly(lactic acid) mode of production of production cost reduces about 40%, the poly-lactic acid products of gained can have same good biocompatibility, biodegradability, mechanical property and workability, and can make corresponding product according to service requirements.Relevant correlation data and result to the poly-lactic acid products that derives from different preparation methods are as shown in table 1.
The related data contrast of the different preparation methods' of table 1 poly-lactic acid products
| Common condensation method | Common open loop method | The inventive method | |
| Average molecular weight range (M) | 50,000～100,000 | 100,000 | 80,000～200,000 |
| Production cost | ＞25 yuan/kg | ＞25 yuan/kg | ＜20 yuan/kg |
| Complete degradation time | In 20 days | ||
| Intensity | ????8-10Mpa | ????10-15Mpa | ????12-15MPa |
The embodiment of form is described in further detail foregoing of the present invention again by the following examples.But the scope that should at this point not be interpreted as the above-mentioned theme of the present invention only limits to following example.Do not breaking away under the above-mentioned technological thought situation of the present invention, all various modifications, replacement or changes of making according to ordinary skill knowledge and customary means include within the scope of the invention.
Embodiment
Embodiment 1
After the twin screw extruder of engagement type in the same way of length 50/1 carried out preheating by the respective reaction temperature, L-L type rac-Lactide lactic acid performed polymer (purity 85%) with 40Kg, 200g monobutyl tin and 150g phosphorous acid are evenly mixed in container, inject feeder then, in the forcing machine that each district's temperature section sets gradually by following mode, react:
130??140??
150??160??175??
170??160??150??
140??135??(℃)
First temperature section, second temperature section the 3rd temperature section the 4th temperature section
Forcing machine engine speed 120r/min, the one-level vacuum tightness of the 3rd temperature section setting is 0.02～0.06MPa, and the secondary vacuum tightness of the 4th temperature section setting is 0.005～0.01Mpa, and the amount of pressing at the 4th temperature section position of forcing machine end 0.002g/ hour is injected H
2Carry out molecular-weight adjusting, the reaction times is 15-30 minute.Obtain poly-lactic acid products 35.7Kg, yield 97.6%.GPC gel chromatography detection molecules amount is 120,000～150,000.
Embodiment 2
To length is after 48/1 the twin screw extruder of engagement type in the same way carries out preheating by the respective reaction temperature, D-D type rac-Lactide lactic acid performed polymer (purity 85%) with 50Kg, 250g diethyl caproic acid stannous salt and 200g triphenyl phosphorus are evenly mixed in container, inject feeder, in the forcing machine that each district's temperature section sets gradually by following mode, react:
140??150??
160??170??180??190??
185??170??
160??150??(℃)
First temperature section, second temperature section the 3rd temperature section the 4th temperature section
Forcing machine engine speed 150r/min, the one-level vacuum tightness in the third and fourth temperature section setting is 0.02～0.06MPa respectively, secondary vacuum tightness is 0.005～0.01Mpa.The amount of pressing 0.008g/ hour at the 4th temperature section position of forcing machine end is injected H
2Carry out molecular-weight adjusting and carry out molecular-weight adjusting, the reaction times is 20-30 minute.Obtain product poly(lactic acid) 49Kg, yield 98%.GPC gel chromatography detection molecules amount is 100,000～150,000.
Embodiment 3
To length is after 52/1 the twin screw extruder of engagement type in the same way carries out preheating by the respective reaction temperature, with the 45Kg polymerization degree is that 20 lactic acid oligomer is (commercially available, purity 85%), 225g monobutyl tin and 175g phosphorous acid are evenly mixed in container, inject feeder then, in the forcing machine that each district's temperature section sets gradually by following mode, react:
135??145??
150??160??170??180??
175??160????
150??140??(℃)
First temperature section, second temperature section the 3rd temperature section the 4th temperature section
Forcing machine engine speed 180r/min, the one-level vacuum tightness of the 3rd temperature section setting is 0.02～0.06MPa, the secondary vacuum tightness of the 4th temperature section setting is 0.005～0.01Mpa.The amount of pressing 0.006g/ hour at the 4th temperature section position of forcing machine end is injected H
2Carry out molecular-weight adjusting, the reaction times is 10-25 minute.Obtain poly-lactic acid products 44.2Kg, yield 98.2%.GPC gel chromatography detection molecules amount is 120,000～180,000.
Claims (5)
1. the preparation method of poly(lactic acid), it is characterized in that in the twin screw extruder of length-to-diameter ratio 〉=40, the raw mix of following composition form is injected by the forcing machine after the relevant temperature preheating, the setting of each temperature of reaction section is followed successively by 130 ℃-170 ℃, 150 ℃-190 ℃, 160 ℃-185 ℃ and 125 ℃-150 ℃, head pressure is 1-5Mpa, engine speed is 50-500 rev/min, the 3rd, in the four temperature of reaction sections respectively the vacuum tightness with 0.005-0.06Mpa pressure be connected with the devolatilization device, and annotate the hydrogen of 0.0001-0.01 weight part continuously as molecular weight regulator at the 3rd temperature section later stage or the 4th temperature section initial stage, the raw mix that injects is carried out successive mediate extrusion reaction, reaction times 5-30 minute, the consisting of of reacting material mixture;
Lactic acid performed polymer 95-99 weight part,
Catalyzer 0.001-3 weight part,
Stablizer 0.001-3 weight part,
Wherein, said lactic acid performed polymer is that the polymerization degree is at least a in the lactic acid oligomer of 10-50 or the lactic acid dimer, said catalyzer is the muriate of tin or in the alkylate any, and said stablizer is any in phosphorous acid or the triphenyl phosphorus.
2. the preparation method of poly(lactic acid) as claimed in claim 1 is characterized in that said lactic acid dimer can be L-L rac-Lactide, any in D-D rac-Lactide and the L-D rac-Lactide.
3. the preparation method of poly(lactic acid) as claimed in claim 1, what it is characterized in that said catalyzer can be in monobutyl tin, diethyl caproic acid Bivalent Tin or their muriate is a kind of.
4. the preparation method of poly(lactic acid) as claimed in claim 1 is characterized in that polyreaction carries out in rotating kneading type double screw rod extruder in the same way.
5. as the preparation method of the described poly(lactic acid) of one of claim 1 to 4, it is characterized in that length-to-diameter ratio 〉=50 of said double screw rod extruder.
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| CN100445320C (en) * | 2006-07-26 | 2008-12-24 | 华南师范大学 | Prepn of polyphosphate |
| CN101374883B (en) * | 2006-01-30 | 2011-06-29 | 株式会社吴羽 | Process for producing aliphatic polyester |
| CN101665564B (en) * | 2009-09-24 | 2011-09-14 | 同济大学 | Membrane-type dehydration-type lactic acid polycondensation reaction device |
| CN101665566B (en) * | 2008-09-01 | 2012-01-04 | 南京工业大学 | Method for preparing polylactic acid and products thereof by utilizing double-screw extruder |
| CN102358778A (en) * | 2011-07-29 | 2012-02-22 | 无锡碧杰生物材料科技有限公司 | Novel biodegradable master batch and preparation method thereof |
| CN103497313A (en) * | 2013-10-10 | 2014-01-08 | 启东市巨龙石油化工装备有限公司 | Polylactic acid production system |
| WO2014180205A1 (en) * | 2013-05-06 | 2014-11-13 | 常州大学 | Method for continuously preparing high molecular weight polyhydroxy acid |
| CN105504250A (en) * | 2015-12-22 | 2016-04-20 | 成都新柯力化工科技有限公司 | Preparation method of low-cost degradable plastics |
| CN105694017A (en) * | 2014-11-28 | 2016-06-22 | 黑龙江鑫达企业集团有限公司 | Twin-screw reactive extrusion method for preparing polylactic acid by ring-opening polymerization |
| CN106893085A (en) * | 2015-12-18 | 2017-06-27 | 四川鑫达企业集团有限公司 | A kind of high-performance poly-lactic acid material and preparation method thereof |
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| TWI636860B (en) * | 2017-07-14 | 2018-10-01 | 寀呈股份有限公司 | Pla composition and manufacturing method of pla product |
| CN109280156A (en) * | 2018-09-13 | 2019-01-29 | 沈阳中博环保科技研发有限公司 | A method of poly-lactic acid in high molecular weight is prepared by double screw extruder |
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| CN101374883B (en) * | 2006-01-30 | 2011-06-29 | 株式会社吴羽 | Process for producing aliphatic polyester |
| CN100445320C (en) * | 2006-07-26 | 2008-12-24 | 华南师范大学 | Prepn of polyphosphate |
| CN101665566B (en) * | 2008-09-01 | 2012-01-04 | 南京工业大学 | Method for preparing polylactic acid and products thereof by utilizing double-screw extruder |
| CN101665564B (en) * | 2009-09-24 | 2011-09-14 | 同济大学 | Membrane-type dehydration-type lactic acid polycondensation reaction device |
| CN102358778A (en) * | 2011-07-29 | 2012-02-22 | 无锡碧杰生物材料科技有限公司 | Novel biodegradable master batch and preparation method thereof |
| CN102358778B (en) * | 2011-07-29 | 2014-06-18 | 上海载和实业投资有限公司 | Novel biodegradable master batch and preparation method thereof |
| GB2528814A (en) * | 2013-05-06 | 2016-02-03 | Univ Changzhou | Method for continuously preparing high molecular weight polyhydroxy acid |
| WO2014180205A1 (en) * | 2013-05-06 | 2014-11-13 | 常州大学 | Method for continuously preparing high molecular weight polyhydroxy acid |
| CN103497313B (en) * | 2013-10-10 | 2015-12-02 | 启东市巨龙石油化工装备有限公司 | polylactic acid production system |
| CN103497313A (en) * | 2013-10-10 | 2014-01-08 | 启东市巨龙石油化工装备有限公司 | Polylactic acid production system |
| CN105694017A (en) * | 2014-11-28 | 2016-06-22 | 黑龙江鑫达企业集团有限公司 | Twin-screw reactive extrusion method for preparing polylactic acid by ring-opening polymerization |
| CN107108864A (en) * | 2015-03-30 | 2017-08-29 | 株式会社吴羽 | The manufacture method of aliphatic polyester composition and article shaped and aliphatic polyester |
| CN106893085A (en) * | 2015-12-18 | 2017-06-27 | 四川鑫达企业集团有限公司 | A kind of high-performance poly-lactic acid material and preparation method thereof |
| CN105504250A (en) * | 2015-12-22 | 2016-04-20 | 成都新柯力化工科技有限公司 | Preparation method of low-cost degradable plastics |
| TWI636860B (en) * | 2017-07-14 | 2018-10-01 | 寀呈股份有限公司 | Pla composition and manufacturing method of pla product |
| CN109280156A (en) * | 2018-09-13 | 2019-01-29 | 沈阳中博环保科技研发有限公司 | A method of poly-lactic acid in high molecular weight is prepared by double screw extruder |
| CN114539172A (en) * | 2022-03-25 | 2022-05-27 | 浙江工业大学 | Method for continuously preparing sulfaquinoxaline without solvent |
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