CN105985512B - A method of producing polylactic acid - Google Patents
A method of producing polylactic acid Download PDFInfo
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- CN105985512B CN105985512B CN201510057335.1A CN201510057335A CN105985512B CN 105985512 B CN105985512 B CN 105985512B CN 201510057335 A CN201510057335 A CN 201510057335A CN 105985512 B CN105985512 B CN 105985512B
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Abstract
The present invention relates to a kind of methods producing polylactic acid.The method includes：Step I, make lactide monomer in a loop reactor, existing for compression fluid and catalyst under the conditions of polymerisation occurs, to obtain including the reaction mass of polylactic acid；The reaction mass is sent into flash tank through pressure reducing valve from the annular-pipe reactor and flashed, so that compression fluid is detached with polylactic acid, directly obtain poly-lactic acid products by step II.The method of the present invention need to can only realize the separation of product and polymerisation medium by decompression operation, and product is directly in pelletized form, need not be granulated again, is easy to industrialization large-scale production, and process equipment is simple, at low cost.
Description
Technical field
The invention belongs to technical field of polymer materials, and in particular to a method of producing polylactic acid.
Background technology
Polylactic acid has good biological degradability, biocompatibility, physical mechanical property and excellent processing performance.Extensively
It is general for packing, many aspects, the polylactic acid article such as shell, container, tableware, medical product, can be in heap after use is dropped
Carbon dioxide and water are decomposed by the microorganisms under the conditions of fertilizer, to alleviate the ring for the getting worse brought by plastic products waste
Border pressure.
In the 1950s, first lactide is made in lactic acid by DuPont Corporation, ring-opening polymerisation is then carried out, this is to close
At the most traditional method of polylactic acid.Main cause is can to obtain the polylactic acid of high molecular weight in this way and its series is spread out
Biology, it is still the current most important process route of industrialized production polylactic acid.Currently, using lactide production polylactic acid
Production method is mainly ontology melt polymerization.The product that ontology melt polymerization obtains is purer, and molecular weight is high, but ontology is poly-
It is higher to close temperature, polymerization latter temperature is generally at 180 DEG C or more, and material viscosity is very big, and heat dissipation is difficult, is easy to cause reaction production
Object darkens, and molecular weight reduces.
Invention content
In order to solve the above technical problem, the present invention provides a kind of methods producing polylactic acid, including：
Step I, make lactide in a loop reactor, existing for compression fluid and catalyst under the conditions of that polymerization occurs is anti-
It answers, to obtain including the reaction mass of polylactic acid；
The reaction mass is sent into flash tank through pressure reducing valve from the annular-pipe reactor and flashed, makes pressure by step II
Contracting fluid is detached with polylactic acid, directly obtains poly-lactic acid products.
According to a specific implementation mode, in step I, the temperature in annular-pipe reactor is 97-180 DEG C, pressure 4.5-
14MPa；Preferably, temperature is 110-150 DEG C, pressure 5.5-10MPa；It is highly preferred that temperature is 130-150 DEG C, pressure is
7.2-10MPa。
According to a specific implementation mode, in step I, the reaction time of polymerisation is 1~60 hour, preferably 3.5-45
Hour.
According to a specific implementation mode, in step I, the molar ratio of lactide and catalyst is 100~10000:1,
It is preferred that 1000-5000:1.
According to another embodiment, the molar ratio of compression fluid and lactide in step I is 8~1:1, 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 distillation
Time is 0.5~1 hour.
According to a specific implementation mode, the compression fluid is selected from carbon monoxide, carbon dioxide, nitrogen, methane, ethane
At least one of with propane.In a specific embodiment, the compression fluid is propane.
According to a specific implementation mode, the lactide in L- lactides, D- lactides, DL- lactides extremely
Few one kind.In a specific embodiment, the compression fluid is L- lactides.
According to a specific implementation mode, the catalyst be selected from glass putty, stannous chloride, stannous octoate, it is benzoic acid stannous,
At least one of the compound of antimony oxide, organic acid rare earth compound and iron, preferably octanoic acid stannous.
According to a specific implementation mode, the flow velocity of material is 7.0~10m/s in annular-pipe reactor.
According to specific implementation mode, in the step I of the above method, the annular-pipe reactor carries chuck, in chuck
Medium is conduction oil or cooling water.In a specific embodiment, medium is conduction oil in the chuck.Adjusting can be passed through
Heat conduction oil temperature controlling reaction temperature in chuck is 97~180 DEG C, preferably 110-150 DEG C, more preferably 130-150 DEG C.
Reaction pressure can be controlled in 4.5~14MPa, preferably in 5.5-10MPa, more preferably in 7.2- by adjusting the addition of material
10MPa.In a specific embodiment, keep compression fluid in a supercritical state, the object in annular-pipe reactor is made using circulating pump
Expect that continuous high speed cycle, the particles of polylactic acid of generation are uniformly suspended in compression fluid.Preferably, the lactide monomer of melting
Temperature is 110~130 DEG C, is entered in reactor through Melt Pump；Catalyst enters through plunger pump in reactor.
In the above-mentioned methods, flash tank carries chuck in the step II, and medium is water in chuck, by adjusting 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 0.5-1 hours.Side through the invention
The obtained poly-lactic acid products of method are colourless, transparent particle.In a particular embodiment, the poly-lactic acid products that step II is obtained
Particle diameter is in 0.2mm between 3mm.
Alcohols can also be added in annular-pipe reactor to control the molecular weight of polymer within the required range.The alcohol can be with
For high-boiling point alcohol, such as lauryl alcohol, tridecanol, tetradecyl alchohol, ethylene glycol, glycerine, polyethylene glycol and polypropylene glycol etc..The alcohol
Weight of the dosage based on lactide be 0.001-10 weight %.
The present invention carries out the production of polylactic acid using annular-pipe reactor, and heat transfer area is larger, and material is uniformly mixed, and with super
Critical compressive fluid is more than the fusing point that lactide monomer fusing point is less than product polylactic acid as polymerisation medium, polymerization temperature, directly
Pelletized product is obtained, solves the problems, such as to remove in ontology melt polymerization technology hot difficult easily colored with product.The method of the present invention only needs
The separation of product and polymerisation medium can be realized by decompression operation, and product is directly in pelletized form, need not be granulated, be easy to again
Industrialization large-scale production, process equipment is simple, at low cost.
Specific implementation mode
With reference to specific embodiment, the present invention will be further described, but does not constitute any limit to the present invention
System.
Embodiment 1
The annular-pipe reactor of a diameter of 500mm, Zhou Changwei 20m are heated to 140 DEG C, taken out reactor very with vacuum system
It is empty.Propane, 110 DEG C of L- lactides melted and octoate catalyst stannous, wherein L- lactides and octanoic acid are added into reactor
The molar ratio of stannous is 1000：1, the molar ratio of propane and L- lactides is 6：1.Utilize the conduction oil in annular-pipe reactor chuck
Controlling reaction temperature is 150 DEG C, after reactor pressure reaches 5.0MPa, opens the circulating pump of annular-pipe reactor, control material
Flow velocity be 7m/s.After the polymerization time of material in the reactor reaches 3.5h, it is sent into flash tank through pressure reducing valve and is flashed, utilized
The equilibrium temperature of the temperature control flash tank of water is 30 DEG C in flash tank chuck, and flash tank pressure is normal pressure, and flash-off time is
1.0h, propane and poly-lactic acid products separation, obtain the particles of polylactic acid that grain size is colourless between 0.2mm to 3mm, transparent.Gained
The weight average molecular weight of poly-lactic acid products is 125000.
Embodiment 2
The annular-pipe reactor of a diameter of 500mm, Zhou Changwei 20m are heated to 130 DEG C, taken out reactor very with vacuum system
It is empty.Propane, 120 DEG C of L- lactides melted and octoate catalyst stannous, wherein L- lactides and octanoic acid are added into reactor
The molar ratio of stannous is 3000：1, the molar ratio of propane and L- lactides is 5：1.Utilize the conduction oil in annular-pipe reactor chuck
Controlling reaction temperature is 140 DEG C, after reactor pressure reaches 7.0MPa, opens the circulating pump of annular-pipe reactor, control material
Flow velocity in 7m/s or more.After the polymerization time of material in the reactor reaches 16.0h, it is sent into flash tank through pressure reducing valve and is dodged
It steams, the equilibrium temperature that flash tank is controlled using the temperature of water in flash tank chuck is 40 DEG C, and flash tank pressure is normal pressure, when flash distillation
Between be 0.8h, propane and poly-lactic acid products separation, obtain the particles of polylactic acid that grain size is colourless between 0.2mm to 2mm, transparent.
The weight average molecular weight of gained poly-lactic acid products is 155000.
Embodiment 3
The annular-pipe reactor of a diameter of 500mm, Zhou Changwei 20m are heated to 130 DEG C, taken out reactor very with vacuum system
It is empty.Propane, 130 DEG C of L- lactides melted and octoate catalyst stannous, wherein L- lactides and octanoic acid are added into reactor
The molar ratio of stannous is 5000：1, the molar ratio of propane and L- lactides is 4：1.Utilize the conduction oil in annular-pipe reactor chuck
Controlling reaction temperature is 130 DEG C, after reactor pressure reaches 10.0MPa, opens the circulating pump of annular-pipe reactor, control material
Flow velocity in 7m/s or more.After the polymerization time of material in the reactor reaches 45.0h, it is sent into flash tank through pressure reducing valve and is dodged
It steams, the equilibrium temperature that flash tank is controlled using the temperature of water in flash tank chuck is 50 DEG C, and flash tank pressure is normal pressure, when flash distillation
Between be 0.5h, propane and poly-lactic acid products separation, obtain the particles of polylactic acid that grain size is colourless between 0.2mm to 3mm, transparent.
The weight average molecular weight of gained poly-lactic acid products is 165000.
Embodiment 4
The annular-pipe reactor of a diameter of 500mm, Zhou Changwei 20m are heated to 140 DEG C, taken out reactor very with vacuum system
It is empty.Propane, 110 DEG C of L- lactides melted and octoate catalyst stannous, wherein L- lactides and octanoic acid are added into reactor
The molar ratio of stannous is 5000：1, the molar ratio of propane and L- lactides is 3：1.Utilize the conduction oil in annular-pipe reactor chuck
Controlling reaction temperature is 140 DEG C, after reactor pressure reaches 8.0MPa, opens the circulating pump of annular-pipe reactor, control material
Flow velocity in 7m/s or more.After the polymerization time of material in the reactor reaches 26.0h, it is sent into flash tank through pressure reducing valve and is dodged
It steams, the equilibrium temperature that flash tank is controlled using the temperature of water in flash tank chuck is 40 DEG C, and flash tank pressure is normal pressure, when flash distillation
Between be 0.9h, propane and poly-lactic acid products separation, obtain the particles of polylactic acid that grain size is colourless between 0.2mm to 3mm, transparent.
The weight average molecular weight of gained poly-lactic acid products is 161000.
Embodiment 5
The annular-pipe reactor of a diameter of 500mm, Zhou Changwei 20m are heated to 150 DEG C, taken out reactor very with vacuum system
It is empty.Propane, 130 DEG C of L- lactides melted and octoate catalyst stannous, wherein L- lactides and octanoic acid are added into reactor
The molar ratio of stannous is 3000：1, the molar ratio of propane and L- lactides is 5：1.Utilize the conduction oil in annular-pipe reactor chuck
Controlling reaction temperature is 150 DEG C, after reactor pressure reaches 6.0MPa, opens the circulating pump of annular-pipe reactor, control material
Flow velocity in 7m/s or more.After the polymerization time of material in the reactor reaches 10.0h, it is sent into flash tank through pressure reducing valve and is dodged
It steams, the equilibrium temperature that flash tank is controlled using the temperature of water in flash tank chuck is 30 DEG C, and flash tank pressure is normal pressure, when flash distillation
Between be 1.0h, propane and poly-lactic acid products separation, obtain the particles of polylactic acid that grain size is colourless between 0.2mm to 2mm, transparent.
The weight average molecular weight of gained poly-lactic acid products is 135000.
Embodiment 6
The annular-pipe reactor of a diameter of 500mm, Zhou Changwei 20m are heated to 130 DEG C, taken out reactor very with vacuum system
It is empty.Propane, 120 DEG C of L- lactides melted and octoate catalyst stannous, wherein L- lactides and octanoic acid are added into reactor
The molar ratio of stannous is 2000：1, the molar ratio of propane and L- lactides is 6：1.Utilize the conduction oil in annular-pipe reactor chuck
Controlling reaction temperature is 140 DEG C, after reactor pressure reaches 9.0MPa, opens the circulating pump of annular-pipe reactor, control material
Flow velocity in 7m/s or more.After the polymerization time of material in the reactor reaches 10.0h, it is sent into flash tank through pressure reducing valve and is dodged
It steams, the equilibrium temperature that flash tank is controlled using the temperature of water in flash tank chuck is 40 DEG C, and flash tank pressure is normal pressure, when flash distillation
Between be 0.8h, propane and poly-lactic acid products separation, obtain the particles of polylactic acid that grain size is colourless between 0.2mm to 3mm, transparent.
The weight average molecular weight of gained poly-lactic acid products is 142000.
As can be seen from the above-described embodiment, method using the present invention produces polylactic acid, only need to can by decompression operation
To realize the separation of product and polymerisation medium, and product is directly in pelletized form, need not be granulated again, is easy to industrialize extensive life
Production, process equipment is simple, at low cost.
Claims (12)
1. a kind of method producing polylactic acid, including：
Step I, make lactide in a loop reactor, existing for compression fluid and catalyst under the conditions of polymerisation occurs,
To obtain including the reaction mass of polylactic acid, the wherein temperature in annular-pipe reactor is 110-150 DEG C, pressure 5.5-10MPa,
The reaction time of polymerisation is 1-60 hours；
The reaction mass is sent into flash tank through pressure reducing valve from the annular-pipe reactor and flashed, compression is made to flow by step II
Body is detached with polylactic acid, directly obtains poly-lactic acid products.
2. according to the method described in claim 1, it is characterized in that, in step I, the temperature in annular-pipe reactor is 130-
150 DEG C, pressure 7.2-10MPa.
3. according to the method described in claim 1, it is characterized in that, the reaction time of the polymerisation in step I is 3.5-45
Hour.
4. according to the method described in claim 1, it is characterized in that, in step I, the molar ratio of lactide and catalyst is
100-10000:1。
5. according to the method described in claim 1, it is characterized in that, in step I, the molar ratio of lactide and catalyst is
1000-5000:1。
6. according to the method described in claim 1, it is characterized in that, compression fluid and the molar ratio of lactide are 8-1:1.
7. according to the method described in claim 1, it is characterized in that, compression fluid and the molar ratio of lactide are 6-3:1.
8. according to the method described in claim 1, it is characterized in that, in step II, the temperature of flash tank is 30-50 DEG C, pressure
For normal pressure, flash-off time is 0.5-1 hours.
9. according to the method described in any one of claim 1-8, which is characterized in that the compression fluid be selected from carbon monoxide,
At least one of carbon dioxide, nitrogen, methane, ethane and propane.
10. according to the method described in any one of claim 1-8, which is characterized in that the lactide is selected from L- lactides, D-
At least one of lactide and DL- lactides.
11. according to the method described in any one of claim 1-8, which is characterized in that the catalyst is selected from glass putty, protochloride
At least one of the compound of tin, stannous octoate, benzoic acid stannous, antimony oxide, organic acid rare earth compound and iron.
12. according to the method described in any one of claim 1-8, which is characterized in that the flow velocity of material is in annular-pipe reactor
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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| CN1241967C (en) * | 2004-06-15 | 2006-02-15 | 东华大学 | Synthesis of polylactate in supercrilical fluid of CO2 |
| CN1285638C (en) * | 2004-06-24 | 2006-11-22 | 同济大学 | Production of polylactic and copolymer PLGA |
| EP2365016B1 (en) * | 2010-03-08 | 2017-05-03 | Ricoh Company, Ltd. | 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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