CN105985512A - Method for producing polylactic acid - Google Patents
Method for producing polylactic acid Download PDFInfo
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- CN105985512A CN105985512A CN201510057335.1A CN201510057335A CN105985512A CN 105985512 A CN105985512 A CN 105985512A CN 201510057335 A CN201510057335 A CN 201510057335A CN 105985512 A CN105985512 A CN 105985512A
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- lactide
- polylactic acid
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Abstract
The invention relates to a method for producing polylactic acid. The method comprises the steps: (I) subjecting lactide monomers to a polymerization reaction in a loop reactor in the presence of compressed fluid and a catalyst, so as to obtain a reactant containing the polylactic acid; and (II) feeding the reactant to a flash evaporation tank for flash evaporation from the loop reactor through a pressure relief valve, and enabling the compressed fluid to be separated from the polylactic acid, thereby directly obtaining the polylactic acid product. According to the method disclosed by the invention, the separation of the product from a polymerization medium can be realized by only depressurizing operation, and the product is directly granular and has no need of granulating, so that industrial large-scale production is facilitated; and the process equipment is simple and is low in cost.
Description
Technical field
The invention belongs to technical field of polymer materials, be specifically related to a kind of method producing polylactic acid.
Background technology
Polylactic acid has the processability of good biological degradability, biocompatibility, physical and mechanical properties and excellence
Energy.Being widely used in many aspects such as packaging, housing, container, tableware, medical product, polylactic acid article makes
After being dropped, carbon dioxide and water can be decomposed by the microorganisms under composting conditions, thus alleviate by plastics system
The most serious ambient pressure that product garbage brings.
The 1950's, first du pont company prepares lactide lactic acid, then carries out ring-opening polymerisation,
This is the method that synthesizing polylactic acid is the most traditional.Main cause is to adopt to obtain the poly-of high molecular in this way
Lactic acid and series derivates thereof, it remains the current topmost process route of industrialized production polylactic acid.At present,
The production method using lactide production polylactic acid is mainly body melt polymerization.The product that body melt polymerization obtains
Product are purer, and molecular weight is high, but bulk polymerization temperature is higher, polymerization latter temperature typically 180 DEG C with
On, and material viscosity is very big, heat radiation difficulty, is easily caused product and darkens, molecular weight reduces.
Summary of the invention
In order to solve above-mentioned technical problem, the invention provides a kind of method producing polylactic acid, including:
Step I, make lactide in a loop reactor, compression fluid and catalyst exist under conditions of occur
Polyreaction, to obtain comprising the reaction mass of polylactic acid；
Step II, sends into flash tank from described annular-pipe reactor through air relief valve by described reaction mass and carries out flash distillation,
Make compression fluid separate with polylactic acid, directly obtain poly-lactic acid products.
According to a detailed description of the invention, in step I, the temperature in annular-pipe reactor is 97-180 DEG C, and pressure is
4.5-14MPa；Preferably, temperature is 110-150 DEG C, and pressure is 5.5-10MPa；It is highly preferred that temperature is
130-150 DEG C, pressure is 7.2-10MPa.
According to a detailed description of the invention, in step I, the response time of polyreaction is 1～60 hour, preferably
3.5-45 hour.
According to a detailed description of the invention, in step I, lactide with the mol ratio of catalyst is
100～10000:1, preferably 1000-5000:1.
According to another embodiment, the compression fluid in step I is 8～1:1 with the mol ratio of lactide,
Preferably 6～3:1.
According to another embodiment, in step II, the temperature of flash tank is 30-50 DEG C, and pressure is normal
Pressure, flash-off time is 0.5～1 hour.
According to a detailed description of the invention, described compression fluid is selected from carbon monoxide, carbon dioxide, nitrogen, first
At least one in alkane, ethane and propane.In a specific embodiment, described compression fluid is propane.
According to a detailed description of the invention, described lactide is selected from L-lactide, D-lactide, DL-lactide
In at least one.In a specific embodiment, described compression fluid is L-lactide.
According to a detailed description of the invention, described catalyst is selected from glass putty, stannous chloride, stannous octoate, benzene first
At least one in the compound of acid stannous, antimony oxide, organic acid rare earth compound and ferrum, preferably octanoic acid
Stannous.
According to a detailed description of the invention, in annular-pipe reactor, the flow velocity of material is 7.0～10m/s.
According to detailed description of the invention, in step I of said method, described annular-pipe reactor with chuck,
Chuck medium is conduction oil or cooling water.In a specific embodiment, described chuck medium is heat conduction
Oil.Can control reaction temperature by the conduction oil temperature in regulation chuck is 97～180 DEG C, is preferably
110-150 DEG C, more preferably 130-150 DEG C.Reaction pressure can be controlled by the addition of regulation material to exist
4.5～14MPa, preferably at 5.5-10MPa, more preferably at 7.2-10MPa.In a specific embodiment, pressure is made
Contracting fluid is in a supercritical state, utilizes circulating pump to make the material continuous high speed in annular-pipe reactor circulate, and generates
Particles of polylactic acid be uniformly suspended in compression fluid in.Preferably, the temperature of melted lactide monomer is
110～130 DEG C, in Melt Pump enters reactor；Catalyst is in plunger displacement pump enters reactor.
In the above-mentioned methods, in described step II, flash tank is with chuck, and chuck medium is water, by regulation
In chuck, the temperature of the temperature control flash tank of water is 30-50 DEG C, and pressure is normal pressure, and flash-off time is that 0.5-1 is little
Time.It is colourless, transparent granule by the poly-lactic acid products obtained by the inventive method.In a particular embodiment,
The particle diameter of the poly-lactic acid products that step II obtains is between 0.2mm to 3mm.
Annular-pipe reactor can also add alcohols by the molecular weight control of polymer within the required range.Described alcohol
Can be high-boiling point alcohol, such as lauryl alcohol, tridecanol, tetradecyl alchohol, ethylene glycol, glycerol, Polyethylene Glycol and
Polypropylene glycol etc..The consumption weight based on lactide of described alcohol is 0.001-10 weight %.
The present invention uses annular-pipe reactor to carry out the production of polylactic acid, and heat transfer area is relatively big, material mix homogeneously,
And using supercritical compression fluid as polymerisation medium, polymerization temperature is poly-less than product more than lactide monomer fusing point newborn
The fusing point of acid, directly obtains pelletized product, solves and removes in body melt polymerization technology that heat is difficult and product is the most colored
Problem.The inventive method only just need to can be realized product and separate with polymerisation medium by decompression operation, and produces
Product are the most in pelletized form, it is not necessary to pelletize again, it is easy to industrialization large-scale production, and process equipment is simple, low cost.
Detailed description of the invention
Below in conjunction with specific embodiment, the present invention will be further described, but be not intended that the present invention any
Limit.
Embodiment 1
By a diameter of 500mm, the annular-pipe reactor of Zhou Changwei 20m is heated to 140 DEG C, will be anti-by vacuum system
Answer device evacuation.Propane, 110 DEG C of melted L-lactides and octoate catalyst stannous is added in reactor,
Wherein L-lactide is 1000:1 with the mol ratio of stannous octoate, and propane is 6:1 with the mol ratio of L-lactide.
Utilizing the conduction oil in annular-pipe reactor chuck to control reaction temperature is 150 DEG C, when reactor pressure reaches
After 5.0MPa, opening the circulating pump of annular-pipe reactor, the flow velocity controlling material is 7m/s.Material is at reactor
In polymerization time reach 3.5h after, through air relief valve send into flash tank carry out flash distillation, utilize water in flash tank chuck
It is 30 DEG C that temperature controls the equilibrium temperature of flash tank, and flash tank pressure is normal pressure, and flash-off time is 1.0h, propane
Separate with poly-lactic acid products, obtain the particles of polylactic acid that particle diameter is colourless, transparent between 0.2mm to 3mm.
The weight average molecular weight of gained poly-lactic acid products is 125000.
Embodiment 2
By a diameter of 500mm, the annular-pipe reactor of Zhou Changwei 20m is heated to 130 DEG C, will be anti-by vacuum system
Answer device evacuation.Propane, 120 DEG C of melted L-lactides and octoate catalyst stannous is added in reactor,
Wherein L-lactide is 3000:1 with the mol ratio of stannous octoate, and propane is 5:1 with the mol ratio of L-lactide.
Utilizing the conduction oil in annular-pipe reactor chuck to control reaction temperature is 140 DEG C, when reactor pressure reaches
After 7.0MPa, open the circulating pump of annular-pipe reactor, control the flow velocity of material at more than 7m/s.Material is instead
After answering the polymerization time in device to reach 16.0h, send into flash tank through air relief valve and carry out flash distillation, utilize flash tank chuck
It is 40 DEG C that the temperature of middle water controls the equilibrium temperature of flash tank, and flash tank pressure is normal pressure, and flash-off time is 0.8h,
Propane separates with poly-lactic acid products, obtains the polylactic acid that particle diameter is colourless, transparent between 0.2mm to 2mm
Grain.The weight average molecular weight of gained poly-lactic acid products is 155000.
Embodiment 3
By a diameter of 500mm, the annular-pipe reactor of Zhou Changwei 20m is heated to 130 DEG C, will be anti-by vacuum system
Answer device evacuation.Propane, 130 DEG C of melted L-lactides and octoate catalyst stannous is added in reactor,
Wherein L-lactide is 5000:1 with the mol ratio of stannous octoate, and propane is 4:1 with the mol ratio of L-lactide.
Utilizing the conduction oil in annular-pipe reactor chuck to control reaction temperature is 130 DEG C, when reactor pressure reaches
After 10.0MPa, open the circulating pump of annular-pipe reactor, control the flow velocity of material at more than 7m/s.Material is instead
After answering the polymerization time in device to reach 45.0h, send into flash tank through air relief valve and carry out flash distillation, utilize flash tank chuck
It is 50 DEG C that the temperature of middle water controls the equilibrium temperature of flash tank, and flash tank pressure is normal pressure, and flash-off time is 0.5h,
Propane separates with poly-lactic acid products, obtains the polylactic acid that particle diameter is colourless, transparent between 0.2mm to 3mm
Grain.The weight average molecular weight of gained poly-lactic acid products is 165000.
Embodiment 4
By a diameter of 500mm, the annular-pipe reactor of Zhou Changwei 20m is heated to 140 DEG C, will be anti-by vacuum system
Answer device evacuation.Propane, 110 DEG C of melted L-lactides and octoate catalyst stannous is added in reactor,
Wherein L-lactide is 5000:1 with the mol ratio of stannous octoate, and propane is 3:1 with the mol ratio of L-lactide.
Utilizing the conduction oil in annular-pipe reactor chuck to control reaction temperature is 140 DEG C, when reactor pressure reaches
After 8.0MPa, open the circulating pump of annular-pipe reactor, control the flow velocity of material at more than 7m/s.Material is instead
After answering the polymerization time in device to reach 26.0h, send into flash tank through air relief valve and carry out flash distillation, utilize flash tank chuck
It is 40 DEG C that the temperature of middle water controls the equilibrium temperature of flash tank, and flash tank pressure is normal pressure, and flash-off time is 0.9h,
Propane separates with poly-lactic acid products, obtains the polylactic acid that particle diameter is colourless, transparent between 0.2mm to 3mm
Grain.The weight average molecular weight of gained poly-lactic acid products is 161000.
Embodiment 5
By a diameter of 500mm, the annular-pipe reactor of Zhou Changwei 20m is heated to 150 DEG C, will by vacuum system
Reactor evacuation.Propane, 130 DEG C of melted L-lactides and octoate catalyst stannous is added in reactor,
Wherein L-lactide is 3000:1 with the mol ratio of stannous octoate, and propane is 5:1 with the mol ratio of L-lactide.
Utilizing the conduction oil in annular-pipe reactor chuck to control reaction temperature is 150 DEG C, when reactor pressure reaches
After 6.0MPa, open the circulating pump of annular-pipe reactor, control the flow velocity of material at more than 7m/s.Material is instead
After answering the polymerization time in device to reach 10.0h, send into flash tank through air relief valve and carry out flash distillation, utilize flash tank chuck
It is 30 DEG C that the temperature of middle water controls the equilibrium temperature of flash tank, and flash tank pressure is normal pressure, and flash-off time is 1.0h,
Propane separates with poly-lactic acid products, obtains the polylactic acid that particle diameter is colourless, transparent between 0.2mm to 2mm
Grain.The weight average molecular weight of gained poly-lactic acid products is 135000.
Embodiment 6
By a diameter of 500mm, the annular-pipe reactor of Zhou Changwei 20m is heated to 130 DEG C, will be anti-by vacuum system
Answer device evacuation.Propane, 120 DEG C of melted L-lactides and octoate catalyst stannous is added in reactor,
Wherein L-lactide is 2000:1 with the mol ratio of stannous octoate, and propane is 6:1 with the mol ratio of L-lactide.
Utilizing the conduction oil in annular-pipe reactor chuck to control reaction temperature is 140 DEG C, when reactor pressure reaches
After 9.0MPa, open the circulating pump of annular-pipe reactor, control the flow velocity of material at more than 7m/s.Material is instead
After answering the polymerization time in device to reach 10.0h, send into flash tank through air relief valve and carry out flash distillation, utilize flash tank chuck
It is 40 DEG C that the temperature of middle water controls the equilibrium temperature of flash tank, and flash tank pressure is normal pressure, and flash-off time is 0.8h,
Propane separates with poly-lactic acid products, obtains the polylactic acid that particle diameter is colourless, transparent between 0.2mm to 3mm
Grain.The weight average molecular weight of gained poly-lactic acid products is 142000.
As can be seen from the above-described embodiment, use the method for the present invention to produce polylactic acid, only need to pass through decompression operation
Just can realize product to separate with polymerisation medium, and product is the most in pelletized form, it is not necessary to pelletize again, it is easy to work
Industry large-scale production, process equipment is simple, low cost.
Claims (10)
1. the method producing polylactic acid, including:
Step I, make lactide in a loop reactor, compression fluid and catalyst exist under conditions of occur
Polyreaction, to obtain comprising the reaction mass of polylactic acid；
Step II, sends into flash tank from described annular-pipe reactor through air relief valve by described reaction mass and carries out flash distillation,
Make compression fluid separate with polylactic acid, directly obtain poly-lactic acid products.
Method the most according to claim 1, it is characterised in that in step I, in annular-pipe reactor
Temperature is 97-180 DEG C, and pressure is 4.5-14MPa；Preferably, temperature is 110-150 DEG C, and pressure is
5.5-10MPa；It is highly preferred that temperature is 130-150 DEG C, pressure is 7.2-10MPa.
Method the most according to claim 1 and 2, it is characterised in that the polyreaction in step I anti-
It is 1～60 hour between Ying Shi, preferably 3.5-45 hour.
4., according to the method according to any one of claim 1-3, it is characterised in that in step I, third hands over
Ester is 100～10000:1 with the mol ratio of catalyst, preferably 1000-5000:1.
5. according to the method according to any one of claim 1-4, it is characterised in that compression fluid and lactide
Mol ratio be 8～1:1, preferably 6～3:1.
6. according to the method according to any one of claim 1-5, it is characterised in that in step II, flash distillation
The temperature of tank is 30-50 DEG C, and pressure is normal pressure, and flash-off time is 0.5～1 hour.
7. according to the method according to any one of claim 1-6, it is characterised in that described compression fluid is selected from
At least one in carbon monoxide, carbon dioxide, nitrogen, methane, ethane and propane, preferably propane.
8. according to the method according to any one of claim 1-7, it is characterised in that described lactide is selected from
At least one in L-lactide, D-lactide, DL-lactide, preferably L-lactide.
9. according to the method according to any one of claim 1-8, it is characterised in that described catalyst is selected from stannum
Powder, stannous chloride, stannous octoate, benzoic acid stannous, antimony oxide, organic acid rare earth compound and ferrum
At least one in compound, preferably octanoic acid stannous.
10. according to the method according to any one of claim 1-9, it is characterised in that thing in annular-pipe reactor
The flow velocity of material is 7.0～10m/s.
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| CN201510057335.1A CN105985512B (en) | 2015-02-04 | 2015-02-04 | A method of producing polylactic acid |
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| CN201510057335.1A CN105985512B (en) | 2015-02-04 | 2015-02-04 | A method of producing polylactic acid |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1583819A (en) * | 2004-06-15 | 2005-02-23 | 东华大学 | Synthesis of polylactate in supercrilical fluid of CO2 |
| CN1712426A (en) * | 2004-06-24 | 2005-12-28 | 同济大学 | Production of polylactic and copolymer PLGA |
| CN102190779A (en) * | 2010-03-08 | 2011-09-21 | 株式会社理光 | Polymer and method for producing the same |
| JP2013166943A (en) * | 2013-03-15 | 2013-08-29 | Ricoh Co Ltd | Method for producing polymer |
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2015
- 2015-02-04 CN CN201510057335.1A patent/CN105985512B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1583819A (en) * | 2004-06-15 | 2005-02-23 | 东华大学 | Synthesis of polylactate in supercrilical fluid of CO2 |
| CN1712426A (en) * | 2004-06-24 | 2005-12-28 | 同济大学 | Production of polylactic and copolymer PLGA |
| CN102190779A (en) * | 2010-03-08 | 2011-09-21 | 株式会社理光 | Polymer and method for producing the same |
| JP2013166943A (en) * | 2013-03-15 | 2013-08-29 | Ricoh Co Ltd | Method for producing polymer |
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