CN109621747A - A kind of doughnut is micro-/preparation method of ultrafiltration membrane - Google Patents
A kind of doughnut is micro-/preparation method of ultrafiltration membrane Download PDFInfo
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- CN109621747A CN109621747A CN201910037619.2A CN201910037619A CN109621747A CN 109621747 A CN109621747 A CN 109621747A CN 201910037619 A CN201910037619 A CN 201910037619A CN 109621747 A CN109621747 A CN 109621747A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
- B01D71/32—Polyalkenyl halides containing fluorine atoms
- B01D71/34—Polyvinylidene fluoride
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/08—Hollow fibre membranes
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Abstract
The invention discloses a kind of doughnut it is micro-/preparation method of ultrafiltration membrane, mainly there is by preparing the macromolecule casting film liquid system of lower critical solution temperature, be film-made at a temperature of suitable spinning head and coagulation bath, obtain structure be easy to regulate and control doughnut it is micro-/ultrafiltration membrane.Macromolecule casting solution of the invention is homogeneous stability at low temperature, but occurs mutually to separate at high temperature, and corresponding film mechanism is different from traditional thermally induced phase separation.New structure hollow-fibre membrane of the invention has the characteristics that flux is big, intensity is high.
Description
Technical field
The invention belongs to polymeric membrane separation technology fields, and in particular to and a kind of doughnut is micro-/the preparation side of ultrafiltration membrane
Method.
Background technique
Micro-filtration and ultrafiltration (referred to as: micro-/ultrafiltration) membrane separation technique is widely used in material filtering separation, concentration purification and net
The fields such as change.The form for commonly using micro-/ultrafiltration membrane has flat and hollow fiber form.Hollow fiber film assembly, which has, loads density
Greatly, the advantages that production capacity is high and be widely used.With the micro-/ultra filtration hollow fiber membrane of Kynoar (PVDF) preparation resistance to
Solvent, acid and alkali-resistance, UV resistant and weatherability, resistance to cleaning etc. performance are prominent.The preparation method master of PVDF hollow-fibre membrane
If phase separation method, it is commonly divided into phase separation method (NIPS) and thermally induced phase separation (TIPS).NIPS method is with dense
The solvent that degree difference is formed is exchanged with non-solvent causes Polymer Solution to be separated into film as mechanism, and TIPS method is lured with temperature difference heat
Causing Polymer Solution to be separated into film is mechanism.Currently used for preparing the TIPS method of pvdf membrane, Polymer Solution
Be commonly upper criticalsolution temperatures (UCST) system, i.e., when Polymer Solution temperature drops to its critical solution temperature from high temperature,
Mutually separation occurs and forms micro-/ultrafiltration membrane.Single NIPS method prepare PVDF doughnut it is micro-/ultrafiltration membrane need regulate and control technique ginseng
Number is numerous, and the porosity of film is lower, and resistance is big, and permeation flux is lower；TIPS method requires high score when preparing PVDF hollow-fibre membrane
The solution temperature of son is very high, the melting temperature usually above PVDF, and up to 180 DEG C or more, energy consumption is high and high molecular for dissolving
Solvent needs to be extracted with organic solvent mostly, and process flow is complicated and environmental pollution is big.In consideration of it, the present invention provides one
Kind of the doughnut based on lower critical solution temperature (LCST) system is micro-/preparation method of ultrafiltration membrane.The low Critical Solution
When referring to that macromolecule homogeneous phase solution is increased to the lower critical solution temperature more than it from low temperature, phase occurs for temperature (LCST) system
Isolated system.
Summary of the invention
The purpose of the present invention is the deficiencies for existing pvdf membrane and its technology of preparing, provide based on lower critical solution temperature
A kind of doughnut of system is micro-/preparation method of ultrafiltration membrane, mainly there is by preparing the PVDF of lower critical solution temperature
Polymer Solution system is film-made at a temperature of suitable spinning head and coagulation bath, obtains the hollow fibre of PVDF that structure is easy to regulate and control
Tie up micro-/ultrafiltration membrane.
The technical scheme of the invention to solve the technical problem is: a kind of doughnut it is micro-/preparation of ultrafiltration membrane
Method, it is characterised in that the following steps are included:
1) it prepares Kynoar (PVDF) casting solution with lower critical solution temperature: pressing macromolecule PVDF mass percentage
Content is 5%-40%, and second of high molecular mass percentage is 1%-20%, and solvent quality percentage composition is 50%-
85%, the mass percentage of small molecule pore-foaming agent is the PVDF casting solution that 1%-20% configures suitable concentration, first by small point
Sub- pore-foaming agent is dissolved completely in solvent, PVDF and second of macromolecule is added later, agitating and heating, which dissolves to be formed, to be completely dissolved
, macromolecule PVDF casting film liquid system with lower critical solution temperature (LCST), standing and defoaming is stand-by；
2) above-mentioned prepared PVDF casting solution is squeezed out in spinning in suitable spinning head under certain spinning temperature
Hollow fiber nascent state film wire controls the flow and spinning speed of casting solution and core liquid, soaks after a certain period of time in air section stop
Enter in the outer coagulation bath of certain temperature, the generation of nascent state film mutually separates, and is wrapped in wound membrane machine from liquid phase film-forming, then by film wire
On；
3) by film be placed in water further in film solvent and the dissolution completely such as magnesium chloride to get to it is of the invention it is poly- partially
Vinyl fluoride is micro-/ultrafiltration membrane.
Kynoar (PVDF) casting solution in the step 1) has lower critical solution temperature (LCST), is being lower than
At a temperature of the LCST, which is uniform Polymer Solution, and when being higher than the LCST temperature, originally uniform PVDF solution
Mutually separation occurs to become cloudy, lower critical solution temperature LCST is between 1 DEG C -125 DEG C, preferably at 35 DEG C -80 DEG C.
PVDF casting solution in the step 1) is the system that quaternary and the above component are constituted, including macromolecule PVDF,
Second of macromolecule, solvent and small molecule pore-foaming agent, small molecule pore-foaming agent must contain magnesium chloride, but can add simultaneously other
Small molecule compound, the small molecule pore-foaming agent magnesium chloride, can be anhydrous magnesium chloride, is also possible to the chlorination containing the crystallization water
Magnesium.
Second of macromolecule in the step 1) is the high molecular material for having preferable compatibility with PVDF, be can be
Water-insoluble macromolecule is also possible to water soluble polymer, the macromolecule such as polyethylene pyrrole with carbonyl in preferred structure unit
Pyrrolidone (PVP), it is without being limited thereto.
Solvent in the step 1) is the solvent that can dissolve PVDF, such as dimethylformamide (DMF), dimethylacetamide
Amine (DMAc), N-Methyl pyrrolidone (NMP), are also possible to the mixed solvent containing the solvent, without being limited thereto, solvent is preferably tied
There is carbonyl in structure unit, can interact to form multi-solvent with small molecule pore-foaming agent magnesium chloride generation electron donor-donor
The solvation magnesium of molecule closes ionic structure such as [Mg (DMAc)6]2+And the solubility parameter difference Δ δ between PVDFs-pIt is less than
3MPa0.5Organic solvent, such as dimethyl acetamide (DMAc).
Small molecule pore-foaming agent magnesium chloride in the step 1), can in the step 1) macromolecule PVDF and
Second of macromolecule generates electron donor-donor interaction effect.
Heating for dissolving temperature in the step 1) is lower than 130 DEG C, while can be higher than LCST temperature, but preferably shorter than
The dissolution of LCST temperature, the macromolecule casting solution temperature after being completely dissolved are maintained at stand-by lower than LCST temperature.
Certain spinning temperature in the step 2), this temperature are usually less than LCST temperature to keep casting solution to be in
Thermodynamics stable state, but can also increase temperature so that initial macromolecule casting solution is crossed binodal line and in metastable state, preferably shorter than
LCST temperature.
Suitable spinning head in the step 2) can be channel structure, and inner-layer channel is core liquid channel, and outer layer is logical
Road is casting solution channel, is also possible to triple channel structure, and inner-layer channel is core liquid channel, and middle layer channel is casting solution channel,
Outermost layer channel can walk gel media or casting solution, when flow through outermost layer channel is gel media, composition and temperature with
Outer coagulation bath can be different, when flow through outermost layer channel is casting solution, composition, temperature and thickness and middle layer channel
Casting solution can be different.
The certain time stopped in air section in the step 2) is 0 to 15 second.
Outer coagulation bath in the step 2) is the non-solvent of PVDF, unlimited such as water, ethyl alcohol, solvent-laden aqueous solution
In this.
Core liquid in the step 2) is the non-solvent of PVDF, such as water, ethyl alcohol, polyethylene glycol, glycerol, solvent-laden water
Solution, it is without being limited thereto.
Outer coagulation bath temperature, core liquid temperature in the step 2) can be lower than LCST temperature, can also be higher than
LCST temperature, but wherein must at least one temperature be higher than LCST temperature and be higher than casting solution temperature, prepare microfiltration membranes
Two temperature of Shi Youxuan are above LCST temperature, when preparing the ultrafiltration membrane of single epidermis separating layer preferably one lower than LCST temperature and
Another is higher than LCST temperature, preparative separation layer in centre and two surfaces preferably use threeway when being the ultrafiltration membrane of macropore supporting layer
Road structure spinning head simultaneously squeezes out two kinds of casting solutions with LCST simultaneously.
Nascent state film in the step 2) is in gel, due at least one in outer coagulation bath temperature, core liquid temperature
A temperature is higher than the LCST temperature of casting solution and is higher than casting solution temperature, therefore the nascent state doughnut under action of thermal difference
There are Thermal inactive (TIPS) mechanism for the phase separation of film.
The PVDF doughnut that the step 3) obtains is micro-/outer diameter of ultrafiltration membrane in 0.4mm-4mm, internal diameter is in 0.2mm-
3mm, average pore size is at 0.01 μm -1.0 μm.
Compared with prior art, the features of the present invention and advantage are:
1. the present invention is using a kind of PVDF casting film liquid system for being based on lower critical solution temperature (LCST).PVDF is one
Kind hemicrystalline macromolecule, structure and characteristic are totally different from the materials such as polysulfones, have had not yet to see and be successfully formed low face
The report of the PVDF system of boundary's solution temperature (LCST).The present invention is by a kind of simultaneously including macromolecule PVDF, second of high score
The quaternary system of sub, specific small molecule pore-foaming agent magnesium chloride and matched solvent is successfully formed a kind of lower critical solution temperature
(LCST) PVDF casting film liquid system is based on this, opens a kind of new way for preparing PVDF hollow-fibre membrane.
2. one kind of the invention is based on the PVDF casting film liquid system of lower critical solution temperature (LCST), formed low critical molten
The mechanism of solution temperature does not rely on system hydrogen bond action and mutually separates caused by temperature elevation process is destroyed, nor due to
Temperature sensitive high molecular presence, but because magnesium chloride can occur with the specific solvent of system and second of macromolecule electronics to
Body-donor interaction, wherein the solvation magnesium of the specific multi-solvent molecule formed closes ion can tie when the temperature rises
Structure changes and causes the interaction variation of different components in the quaternary system, to reduce dissolution of the macromolecule in the system
Ability promotees the generation that phases were separated.Casting film liquid system with lower critical solution temperature (LCST), if with lithium chloride or chlorination
Zinc etc. replaces magnesium chloride, and other components are constant, then lower critical solution temperature is not present in foregoing temperature range in new system
(LCST)；In addition, become ternary system from quaternary system if removing second of macromolecule or magnesium chloride from the system, then three
Lower critical solution temperature is also not present in foregoing temperature range in first system.
3. a kind of doughnut of the invention based on lower critical solution temperature system is micro-/preparation method of ultrafiltration membrane, no
It is same as traditional NIPS method and TIPS method film.Mutually separation in film-forming process of the invention includes at least a kind of based on low critical
The TIPS phase process of solution temperature (LCST), this TIPS phase process are different from traditional TIPS phase process.Traditional
TIPS phase process, PVDF solution be at high operating temperatures it is stable, occur mutually to separate at low temperature, corresponding UCST system；And
TIPS phase process involved in the present invention, PVDF solution be under low-temperature condition it is stable, occur mutually to separate at high temperature, it is right
LCST system is answered, is a kind of PVDF hollow-fibre membrane preparation process different from conventional method.
4. a kind of a kind of doughnut based on lower critical solution temperature system of the invention is micro-/the preparation side of ultrafiltration membrane
Method, with single NIPS method prepare doughnut it is micro-/ultrafiltration membrane compared with, do not need numerous technological parameters, and epidermis
Aperture be easy to regulate and control；With single traditional TIPS method prepare doughnut it is micro-/ultrafiltration membrane compared with, do not need to higher than PVDF
The casting solution of melting temperature (up to 180 DEG C or more) is operated, as long as or even under the conditions of 90 DEG C of gelling temps below
Split-phase film forming, low energy consumption and process flow is simple.Gel prepares PVDF hollow-fibre membrane at a temperature of being higher than LCST, passes through change
Outer coagulation bath, core liquid and spinneret header structure in spinning technique can be very easy to be prepared with the ultrafiltration membrane of epidermis separating layer, divide
Absciss layer in centre and two surfaces are the asymmetric of the ultrafiltration membrane of macropore supporting layer, the microfiltration membranes without epidermis and graded pore structure
Microfiltration membranes, this is difficult to realize for the preparation of plate membrane.Its separating layer is ultra-thin when the present invention prepares ultrafiltration membrane, and body layer is
High porosity, large aperture sponge pore structure, formed microfiltration membranes when, be not the high porosity of epidermis, aperture is adjustable and hole
Sponge pore structure or high porosity, the asymmetric microfiltration membranes of gradient sponge pore structure of diameter narrowly distributing, not with conventional membrane structure
Together, the characteristics of flux is big, resistance is low, intensity is high so that new structural hollow-fibre membrane has, and adapts to multi-field application.
Detailed description of the invention
Fig. 1 is the cross section structure SEM figure of PVDF hollow fiber microfiltration membrane prepared by the embodiment of the present invention 1.
Specific embodiment
Present invention is further described in detail with reference to embodiments.
Embodiment 1
It is 12% by macromolecule PVDF mass percentage, the quality of second of high molecular polythene pyrrolidones (PVP)
Percentage composition is 12%, and solvent DMAc mass percentage is 68%, and the mass percentage of small molecule pore-foaming agent magnesium chloride is
Magnesium chloride, is dissolved completely in DMAc first, PVDF and PVP is added later, agitating and heating is in 40 by 8% configuration PVDF casting solution
DEG C constant temperature dissolves the PVDF casting solution to form substantially uniformity, standing and defoaming.Later, by above-mentioned prepared PVDF casting solution 40
Spinning doughnut nascent state film wire is squeezed out at DEG C in the spinning head of channel structure, inner-layer channel is core liquid channel, outer layer
Channel is casting solution channel, and the water that core liquid is 90 DEG C controls the flow and spinning speed of casting solution and core liquid, stops in air section
It is immersed after staying 1 second in 90 DEG C of outer gel bath water, the generation of nascent state film mutually separates, and winds from liquid phase film-forming, then by film wire
On wound membrane machine, by film be placed in water further in film solvent and the dissolution completely such as magnesium chloride to get to of the invention poly-
Vinylidene hollow-fibre membrane.
The lower critical solution temperature (LCST) of the PVDF casting film liquid system is 50 DEG C.Based on the lower critical solution temperature system
Hollow-fibre membrane filming technology in gelling temp ratio LCST temperature it is 40 DEG C high.The membrane structure of preparation is spongy pore structure
Microfiltration membranes, as shown in Figure 1.The outer diameter of hollow-fibre membrane is 1.2mm, and internal diameter 0.7mm, average pore size is 0.2 μm, extension at break
Rate is 250%, breaking strength 3.5MPa.
Embodiment 2
It is 16% by macromolecule PVDF mass percentage, the quality of second of high molecular polythene pyrrolidones (PVP)
Percentage composition is 4%, and solvent DMAc mass percentage is 72%, and the mass percentage of small molecule pore-foaming agent magnesium chloride is
Magnesium chloride, is dissolved completely in DMAc first, PVDF and PVP is added later, agitating and heating is in 45 by 8% configuration PVDF casting solution
DEG C constant temperature dissolves the PVDF casting solution to form substantially uniformity, standing and defoaming.Later, by above-mentioned prepared PVDF casting solution 45
Spinning doughnut nascent state film wire is squeezed out at DEG C in the spinning head of channel structure, inner-layer channel is core liquid channel, outer layer
Channel is casting solution channel, and the water that core liquid is 45 DEG C controls the flow and spinning speed of casting solution and core liquid, is directly immersed in 95
DEG C outer gel bath water in, nascent state film generation mutually separate, be wrapped on wound membrane machine from liquid phase film-forming, then by film wire, will
Film be placed in water further in film solvent and the dissolution completely such as magnesium chloride to get to PVDF hollow-fibre membrane of the invention.
The lower critical solution temperature (LCST) of the PVDF casting film liquid system is 50 DEG C.Based on the lower critical solution temperature system
Hollow-fibre membrane filming technology in outer gelling temp ratio LCST temperature it is 45 DEG C high, core liquid temperature ratio LCST temperature is 5 DEG C low.It obtains
Be there is ultra-thin endodermis and main body is the uni-endodermis ultrafiltration membrane of spongy pore structure.The outer diameter of hollow-fibre membrane is
1.4mm, internal diameter 0.8mm, average pore size are 0.03 μm, elongation at break 270%, breaking strength 3.8MPa.
Embodiment 3
It is 12% by macromolecule PVDF mass percentage, the quality of second of high molecular polythene pyrrolidones (PVP)
Percentage composition is 4%, and solvent DMAc mass percentage is 73%, and the mass percentage of small molecule pore-foaming agent magnesium chloride is
11% configuration PVDF casting solution, magnesium chloride is dissolved completely in DMAc first, later be added PVDF and PVP, agitating and heating in
35 DEG C of constant temperature dissolve the PVDF casting solution to form substantially uniformity, standing and defoaming.Later, above-mentioned prepared PVDF casting solution is existed
Spinning doughnut nascent state film wire is squeezed out at 35 DEG C in the spinning head of triple channel structure, inner-layer channel is core liquid channel, core
The water that liquid is 93 DEG C, middle layer channel are casting solution channel, and outermost layer channel is gel media channel, and gel media is 93 DEG C
Water, the flow and spinning speed of control casting solution, outermost layer gel media and core liquid immerse again after air section stops 5 seconds
In 35 DEG C of outer gel bath water, nascent state film is wrapped on wound membrane machine from liquid phase film-forming, then by film wire, and film is placed in water
Further in film solvent and the dissolution completely such as magnesium chloride to get arriving Pvdf Microporous Hollow Fiber Membrane of the invention.
The lower critical solution temperature (LCST) of the PVDF casting film liquid system is 43 DEG C.Based on the lower critical solution temperature system
Hollow-fibre membrane filming technology in outermost layer channel gel media and core liquid temperature it is 50 DEG C higher than LCST temperature,
Air section has had occurred Thermal inactive, immerse temperature lower than after the outer gel bath water of LCST will further by solvent with it is non-molten
Agent is exchanged nascent state hollow-fibre membrane solidified forming.The hollow fiber film structure of preparation is the microfiltration membranes of spongy pore structure,
The outer diameter of film is 1.0mm, internal diameter 0.5mm, and average pore size is 0.15 μm, elongation at break 260%, and breaking strength is
3.3MPa。
Embodiment 4
Hollow-fibre membrane is spinned with the spinning head of triple channel structure.It is 12% by macromolecule PVDF mass percentage, the
The mass percentage of two kinds of high molecular polythene pyrrolidones (PVP) is 4%, and solvent DMAc mass percentage is 73%,
The mass percentage of small molecule pore-foaming agent magnesium chloride is 11% configuration PVDF casting solution, is first dissolved completely in magnesium chloride
In DMAc, PVDF and PVP is added later, agitating and heating dissolves the PVDF casting solution to form substantially uniformity in 35 DEG C of constant temperature, stands
Deaeration is kept the temperature, this casting solution walks the middle layer channel of triple channel structure spinning head.In addition, pressing macromolecule PVDF mass percentage
It is 13%, the mass percentage of second of high molecular polythene pyrrolidones (PVP) is 3%, solvent NMP mass percentage
It is 74%, the mass percentage of small molecule pore-foaming agent magnesium chloride is 10% another PVDF casting solution of configuration, first by magnesium chloride
It is dissolved completely in NMP, PVDF and PVP is added later, agitating and heating dissolves the PVDF casting to form substantially uniformity in 70 DEG C of constant temperature
Film liquid, stands heat preservation deaeration, this casting solution walks the outermost layer channel of triple channel structure spinning head.
Later, above-mentioned prepared two kinds of PVDF casting solutions are squeezed out into the hollow fibre of spinning in the spinning head of triple channel structure
Tie up nascent state film wire, inner-layer channel is core liquid channel, and core liquid is 93 DEG C of water, control two kinds of casting solutions and core liquid flow and
Spinning speed is directly immersed in 93 DEG C of outer gel bath water, and nascent state film is wrapped in wound membrane from liquid phase film-forming, then by film wire
On machine, by film be placed in water further in film solvent and the dissolution completely such as magnesium chloride to get to polyvinylidene fluoride of the invention
Alkene hollow-fibre membrane.
The lower critical solution temperature (LCST) of the PVDF casting film liquid system in middle layer channel is 43 DEG C, the side contacted
It is 70 DEG C of casting solutions in outermost layer channel, the core liquid that the other side is 93 DEG C, temperature difference is different, and there are temperature gradients in film.Most
The lower critical solution temperature (LCST) of the PVDF casting film liquid system of outer layer channel is 78 DEG C, and the side contacted is 93 DEG C outer
Coagulation bath, the other side are 35 DEG C of the PVDF casting solutions in middle layer channel.Lower critical solution temperature based on the bilayer casting solution
The hollow fiber film structure of system preparation is separating layer in centre and two surfaces are the unsymmetric structure ultrafiltration membrane of macropore supporting layer,
The outer diameter of film is 1.5mm, internal diameter 0.8mm, average pore size 40nm, and elongation at break 300%, breaking strength is
3.6MPa。
Comparative example 1
Outer coagulation bath and core liquid are 20 DEG C of water, remaining is the same as embodiment 1, the low Critical Solution of the PVDF casting film liquid system
Temperature (LCST) is 50 DEG C.Since the gelling temp ratio LCST temperature in filming technology is 30 DEG C low, Thermal inactive does not occur, is
Simple phase separation mechanism, what is prepared is that cortex is thicker, ultrafiltration membrane of finger-like pore structure.Outside hollow-fibre membrane
Diameter is 1.4mm, and internal diameter 0.8mm, average pore size is 0.02 μm, elongation at break 200%, breaking strength 2.5MPa.
Comparative example 2
It is 12% by macromolecule PVDF mass percentage, the quality of second of high molecular polythene pyrrolidones (PVP)
Percentage composition is 0%, and solvent DMAc mass percentage is 80%, and the mass percentage of small molecule pore-foaming agent magnesium chloride is
8% configuration PVDF casting solution, remaining forms the PVDF casting solution of substantially uniformity with 1 step of embodiment through dissolving.
Lower critical solution temperature (LCST) is not present between 1 DEG C -125 DEG C in the PVDF casting film liquid system, the ternary system
LCST system of the invention cannot be formed.
Comparative example 3
It is 12% by macromolecule PVDF mass percentage, the quality of second of high molecular polythene pyrrolidones (PVP)
Percentage composition is 12%, and solvent DMAc mass percentage is 76%, and the mass percentage of small molecule pore-foaming agent magnesium chloride is
0% configuration PVDF casting solution, remaining forms the PVDF casting solution of substantially uniformity with 1 step of embodiment through dissolving.
Lower critical solution temperature (LCST) is not present between 1 DEG C -125 DEG C in the PVDF casting film liquid system, the ternary system
LCST system of the invention cannot be formed.
Comparative example 4
It is 12% by macromolecule PVDF mass percentage, the quality of second of high molecular polythene pyrrolidones (PVP)
Percentage composition is 11.5%, and solvent DMAc mass percentage is 68%, and small molecule pore-foaming agent is changed to lithium chloride, quality percentage
Content is 8.5% configuration PVDF casting solution, remaining forms the PVDF casting solution of substantially uniformity with 1 step of embodiment through dissolving.
Lower critical solution temperature (LCST) is not present between 1 DEG C -125 DEG C in the PVDF casting film liquid system, the quaternary system
LCST system of the invention cannot be formed.
Comparative example 5
It is 12% by macromolecule PVDF mass percentage, the quality of second of high molecular polythene pyrrolidones (PVP)
Percentage composition is 12, and solvent DMAc mass percentage is 71%, and small molecule pore-foaming agent is changed to zinc chloride, mass percentage
For 5% configuration PVDF casting solution, remaining forms the PVDF casting solution of substantially uniformity with 1 step of embodiment through dissolving.
Lower critical solution temperature (LCST) is not present between 1 DEG C -125 DEG C in the PVDF casting film liquid system, the quaternary system
LCST system of the invention cannot be formed.
Claims (10)
1. a kind of doughnut is micro-/preparation method of ultrafiltration membrane, it is characterised in that the following steps are included:
1) it prepares Kynoar (PVDF) casting solution with lower critical solution temperature: pressing macromolecule PVDF mass percentage
For 5%-40%, second of high molecular mass percentage is 1%-20%, and solvent quality percentage composition is 50%-85%,
The mass percentage of small molecule pore-foaming agent is the PVDF casting solution that 1%-20% configures suitable concentration, first by small molecule pore
Agent is dissolved completely in solvent, is added PVDF and second of macromolecule later, agitating and heating dissolve to be formed it is being completely dissolved, have
The macromolecule PVDF casting film liquid system of lower critical solution temperature (LCST), standing and defoaming are stand-by；
2) above-mentioned prepared PVDF casting solution is squeezed out in suitable spinning head under certain spinning temperature and spins hollow fibre
Nascent state film wire is tieed up, the flow and spinning speed of casting solution and core liquid are controlled, immerses one after a certain period of time in air section stop
Determine in the outer coagulation bath of temperature, the generation of nascent state film mutually separates, and is wrapped on wound membrane machine from liquid phase film-forming, then by film wire；
3) by film be placed in water further in film solvent and the dissolution completely such as small molecule pore-foaming agent to get to of the invention poly-
Vinylidene is micro-/ultrafiltration membrane.
2. a kind of doughnut according to claim 1 is micro-/preparation method of ultrafiltration membrane, which is characterized in that in step 1)
Kynoar (PVDF) casting solution have lower critical solution temperature (LCST), be lower than the LCST at a temperature of, the casting solution
It is uniform Polymer Solution, and when being higher than the LCST temperature, uniform PVDF solution occurs mutually separation and becomes cloudy originally, this is low
Critical solution temperature (LCST) is between 1 DEG C -125 DEG C, preferably at 35 DEG C -80 DEG C.
3. a kind of doughnut according to claim 1 is micro-/preparation method of ultrafiltration membrane, which is characterized in that in step 1)
PVDF casting solution be system that quaternary and the above component are constituted, including macromolecule PVDF, second of macromolecule, solvent and small point
Sub- pore-foaming agent, small molecule pore-foaming agent must contain magnesium chloride, but can add other small molecule compounds simultaneously, and described small point
Sub- pore-foaming agent magnesium chloride, can be anhydrous magnesium chloride, be also possible to the magnesium chloride containing the crystallization water.
4. a kind of doughnut according to claim 1 is micro-/preparation method of ultrafiltration membrane, which is characterized in that in step 1)
Second of macromolecule be the high molecular material that there is preferable compatibility with PVDF, can be water-insoluble macromolecule, can also be with
It is water soluble polymer, the macromolecule such as polyvinylpyrrolidone (PVP) with carbonyl in preferred structure unit is without being limited thereto.
5. a kind of doughnut according to claim 1 is micro-/preparation method of ultrafiltration membrane, which is characterized in that in step 1)
Solvent be the solvent that can dissolve PVDF, such as dimethylformamide (DMF), dimethyl acetamide (DMAc), N- crassitude
Ketone (NMP) is also possible to the mixed solvent containing the solvent, without being limited thereto, in solvent preferred structure unit have carbonyl, can
Electron donor-donor occurs with small molecule pore-foaming agent magnesium chloride to interact to form the solvation magnesium conjunction ion knot of multi-solvent molecule
Structure such as [Mg (DMAc)6]2+And the solubility parameter difference Δ δ between PVDFs-pLess than 3MPa0.5Organic solvent, such as dimethyl second
Amide (DMAc).
6. a kind of doughnut according to claim 1 is micro-/preparation method of ultrafiltration membrane, which is characterized in that in step 2)
Certain spinning temperature, this temperature is usually less than LCST temperature to keep casting solution to be in thermodynamics stable state, but can also rise
High-temperature makes initial macromolecule casting solution cross binodal line and is in metastable state, preferably shorter than LCST temperature.
7. a kind of doughnut according to claim 1 is micro-/preparation method of ultrafiltration membrane, which is characterized in that in step 2)
Suitable spinning head, can be channel structure, inner-layer channel is core liquid channel, and outer layer channel is casting solution channel, can also be with
It is triple channel structure, inner-layer channel is core liquid channel, and middle layer channel is casting solution channel, and outermost layer channel can walk gel media
Or casting solution, when flow through outermost layer channel is gel media, composition and temperature can be different from outer coagulation bath, when flowing through
Outermost layer channel be casting solution when, composition, temperature and thickness can be different from the casting solution in middle layer channel.
8. a kind of doughnut according to claim 1 is micro-/preparation method of ultrafiltration membrane, which is characterized in that in step 2)
It is 0 to 15 second in the certain time that air section stops, immerses outer coagulation bath later, outer coagulation bath temperature, core liquid temperature can be with
Lower than LCST temperature, LCST temperature can also be higher than, but wherein must at least one temperature be higher than LCST temperature and height
In casting solution temperature, preferably two temperature are above LCST temperature when preparing microfiltration membranes, prepare the ultrafiltration membrane of single epidermis separating layer
Shi Youxuan mono- lower than LCST temperature and another is higher than LCST temperature, preparative separation layer in centre and two surfaces are that macropore supports
Triple channel structure spinning head is preferably used when the ultrafiltration membrane of layer and while squeezing out two kinds of casting solutions with LCST.
9. a kind of doughnut according to claim 1 is micro-/preparation method of ultrafiltration membrane, which is characterized in that in step 2)
Nascent state film in gel, since the temperature of at least one in outer coagulation bath temperature, core liquid temperature is higher than casting solution
LCST temperature and be higher than casting solution temperature, therefore under action of thermal difference nascent state hollow-fibre membrane phase separation exist heat
It causes mutually to separate (TIPS) mechanism.
10. a kind of doughnut according to claim 1 is micro-/preparation method of ultrafiltration membrane, which is characterized in that step 3)
The PVDF doughnut arrived is micro-/outer diameter of ultrafiltration membrane in 0.4mm-4mm, internal diameter in 0.2mm-3mm, average pore size 0.01 μm-
1.0μm。
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