A kind of polytetrafluoroethyltubular tubular membrane and preparation method thereofTechnical field
The present invention relates to polytetrafluoroethyltubular tubular membranes and preparation method thereof to be particularly suitable for membrane distillation for separating.
Technical background
Polytetrafluoroethylene (PTFE) since its use temperature range is wide, while have excellent chemical stability, low frictional properties and absolutelyEdge thermal insulation not only has excellent chemical stability, thermal stability, electricity using the separation membrane material that polytetrafluoroethylene (PTFE) is prepared as raw materialInsulating properties also has the characteristics such as outstanding waterproof, radix saposhnikoviae, moisture-inhibiting, ventilative and charge stable storing.It is in manufacture protective garment, bagFormula deduster, architectural lighting etc. have shown excellent performance.National Palaestra " Bird Nest ", dome in thousand of Britain etc.A large amount of PTFE microporous barriers are used.However that there are still flux in the application is small, filtering essence for current microporous teflon membranThe disadvantages of low, fenestra is easy to pollute, at high cost is spent, the application of industrialized production is had not been achievable.
Inventor has been devoted to the research to the structure of high molecular material, and the control and modification to material structure can getThe high molecular material of different characteristics and function.However polytetrafluoroethylene film relation be- tween structure and properties are not made clear of at presentIt is thorough, as separation accuracy is difficult to take into account with treatment effeciency；With accurate microstructure, it is easy to impaired, service phase is short, use costIt is high；Polytetrafluoroethylene (PTFE) physical and chemical performance is stablized, and structure control, performance improvement realize difficulty is big, and difficulty of processing is big etc.；Polytetrafluoroethyl-neAlkene material is in separation in application, how to cooperate with matching to obtain better performance etc. between microstructure and macroscopic form.
Summary of the invention
The purpose of the present invention is to provide a kind of polytetrafluoroethyltubular tubular membranes, and service phase is long, the processing big to complicated, difficultyObject has preferable separating effect.
The purpose of the present invention is what is realized by following measures:
A kind of polytetrafluoroethyltubular tubular membrane has the pore structure of three-dimensional perforation, there is transforaminal, 300nm < hole on the stem of holeLyriform pore diameter < 600nm, 200nm < stem diameter < 400nm, 70nm < transforaminal aperture < 150nm；Wherein the porosity of hole be 60 ±10%, the porosity of transforaminal is 55 ± 10%；The total surface area of the stem, stem area: transforaminal area=16-30:1；Bore is greater than2mm, thickness of pipe wall are not less than 0.1mm.The film is during the Selective Separation for substance, when one such or a variety of pointFor son when through material surface and/or inside, the microstructure of molecule will receive itself and the effect of material and the shadow of bond structureIt rings, to affect the percent of pass and throughput of substance, the microstructure of another aspect material also will receive influence, to influenceMaterial separation tower, service phase etc..So both ensure that separate substance by efficiency and throughput, combine making for materialWith rate.Distribution situation of the transforaminal on stem is one of key factor.
Preferably, in order to further increase correlated performance, the polytetrafluoroethyltubular tubular membrane, hole aperture is 450-500nm, stem diameter 210-260nm, transforaminal aperture 80-120nm；Wherein the porosity of hole is 55-65%, the hole of transforaminalRate is 50-55%；The total surface area of the stem, stem area: transforaminal area=18-25:1.
Preferably, bore is greater than 2mm and is less than 50mm, thickness of pipe wall 0.15-2mm.
Polytetrafluoroethylene (PTFE) has stable inert physical and chemical performance, and processing is not easy, especially for its microstructureControl and holding are even more industry problem.The present invention provides the preparation method of the polytetrafluoroethyltubular tubular membrane of above-mentioned special construction,Using method of electrostatic spinning, including the preparation of spinning lotion, spinning, preforming, sintering, temperature-control pressure-control continuous sintering in the sintering；It is described it is preforming be that the precursor film for obtaining spinning is wrapped on cylinder branch hold mode formation tubular type form；Winding circle number is controllably film-madeIt is thick.
The present invention provides the preparation method with the PTFE high molecular material of above structure, comprising the following steps:
(1) spinning solution prepares: polytetrafluoroethylene (PTFE) is added in the sodium alginate homogeneous solution soluble in water for obtaining 14-15% concentration(PTFE) lotion (55-60%), so that PTFE and sodium alginate mass ratio are 2-3:1；
(2) spinning: electrostatic spinning is carried out using high-voltage electrostatic spinning apparatus, obtains even fiber precursor film；Spinning voltage15 ~ 20kV, 12 ~ 30cm of distance；
(3) preforming: the precursor film that spinning is obtained is wrapped on cylinder branch hold mode of the outer diameter greater than 2mm and forms tubular type form；
(4) be sintered: 1. under a high vacuum (3-5Pa) with 5-6 DEG C/min from room temperature to 98-103 DEG C, and keep temperature and pressurePower 25-30min；2. nitrogen is filled in 60-150s to pressure 65-70kpa, at the same with 4-5 DEG C/that min is warming up to temperature value is bigIt is not more than 385 DEG C in 380 DEG C, and keeps 8- in the case where pressure value 65-70kpa, temperature value are greater than 380 DEG C no more than 385 DEG C12min；3. after heating, keeping vacuum to cooling to 50-100Pa.
Above-mentioned spinning lotion is prepared as preparing high molecular polymerization composition granule, the high molecular polymer using emulsion polymerizationGrain average grain diameter is 15-80nm.This makes material have better stem, pore size, optimizes the property such as impact flexibility, ageing resistanceEnergy.
Porosity=hole porosity of material+(porosity of 1- hole) * transforaminal porosity
Beneficial effect
1. the present invention improves the treating capacity that material carries out substance selection by the improvement to polytetrafluoroethylene (PTFE) semi-permeable material structureWith the persistence of selection performance, the efficiency of selection and selection effect of material are higher, and the service phase of material is long.And to high-leveled and difficultObject is spent, such as highly concentrated, high viscosity waste water processing has excellent effect.
2. the super-hydrophobic polytetrafluoroethylfiber fiber film that the present invention is coupled hardness with softness has stable and firm fibre morphologyWith transforaminal structure, collapsing for bone skeleton is prevented.
Specific embodiment
The present invention is specifically described below by embodiment, it is necessary to which indicated herein is that the present embodiment can only be usedIn invention is further explained, it should not be understood as limiting the scope of the invention, the people that is skilled in technique in the fieldMember can make some nonessential modifications and adaptations according to the content of aforementioned present invention.
Embodiment 1
The polytetrafluoroethyltubular tubular membrane of the present embodiment has the pore structure of three-dimensional perforation, has transforaminal on the stem of hole,300nm < hole aperture < 600nm, 200nm < stem diameter < 400nm, 70nm < transforaminal aperture < 150nm；The wherein porosity of holeIt is 60 ± 10%, the porosity of transforaminal is 55 ± 10%；The total surface area of the stem, stem area: transforaminal area=16-30:1；In pipeDiameter is greater than 2mm and is less than 50mm, thickness of pipe wall 0.15-2mm.
Stem surface area image analysis: with scanning electron microscope (SEM photograph amplifies 10000-50000 times) shooting materialPhoto.The photo (the television image processor TVIP- of Japanese Avionics company production is scanned with image processing equipmentThe television image processor that 4100II, Latock system engineering company provide) stem and transforaminal are separated to obtain stem and transforaminal figurePicture handles image by software, obtains respective area, can calculate the ratio between stem area and transforaminal area total image area.
Aperture, stem diameter, porosity are detected using nanometer CT.
The preparation method of this polytetrafluoroethyltubular tubular membrane, according to the following steps:
(1) spinning solution prepares: polytetrafluoroethylene (PTFE) is added in the sodium alginate homogeneous solution soluble in water for obtaining 14-15% concentration(PTFE) lotion (55-60%), so that PTFE and sodium alginate mass ratio are 2-3:1；
(2) spinning: electrostatic spinning is carried out using high-voltage electrostatic spinning apparatus, obtains even fiber precursor film；Spinning voltage15 ~ 20kV, 12 ~ 30cm of distance；
(3) preforming: the precursor film that spinning is obtained is wrapped in outer diameter greater than formation pipe on cylinder branch hold mode of the 2mm less than 50mmFormula form；
(4) be sintered: 1. under a high vacuum (3-5Pa) with 5-6 DEG C/min from room temperature to 98-103 DEG C, and keep temperature and pressurePower 25-30min；2. nitrogen is filled in 60-150s to pressure 65-70kpa, at the same with 4-5 DEG C/that min is warming up to temperature value is bigIt is not more than 385 DEG C in 380 DEG C, and keeps 8- in the case where pressure value 65-70kpa, temperature value are greater than 380 DEG C no more than 385 DEG C12min；3. after heating, keeping vacuum to cooling to 50-100Pa.
158-171 ° of resulting materials hydrophobic angle.Gained PTFE material is subjected to membrane distillation: for hc effluent, being contained Ru highly concentratedThe processing of phenol waste water and highly concentrated brine waste is adapted to industrial excellent properties and effect.As processes composition is complicated,High-concentration salt-containing wastewater (by taking saccharin sodium produces waste water as an example), Na ion concentration is 3.5g/L, sulfate concentration 8.0g/L,DOC is greater than 8.0g/L.It can reach discharge standard after processing.Flux of membrane distillation > 20L/m2H, rejection are stablized 99% or more,It is carried out continuously membrane distillation 3-4 months, flux drops to former flux 65-72%, and material color is pure white, flux recovery after cleaningTo before 95% or more, service phase is 3-5.
Embodiment 2
The polytetrafluoroethyltubular tubular membrane of the present embodiment has the pore structure of three-dimensional perforation, there is transforaminal, hole on the stem of holeLyriform pore diameter is 450-500nm, stem diameter 210-260nm, transforaminal aperture 80-120nm；Wherein the porosity of hole is 55-65%, the porosity of transforaminal is 50-55%；The total surface area of the stem, stem area: transforaminal area=18-25:1.Bore is greater than2mm is less than 50mm, thickness of pipe wall 0.15-2mm.
160-172 ° of resulting materials hydrophobic angle.Gained PTFE material is subjected to membrane distillation: for hc effluent, being contained Ru highly concentratedThe processing of phenol waste water and highly concentrated brine waste is adapted to industrial excellent properties and effect.As processes composition is complicated,High-concentration salt-containing wastewater (by taking saccharin sodium produces waste water as an example), Na ion concentration is 3.5g/L, sulfate concentration 8.0g/L,DOC is greater than 8.0g/L.It can reach discharge standard after processing.Flux of membrane distillation > 20L/m2H, rejection are stablized 99% or more,It is carried out continuously membrane distillation 3-4 months, flux drops to former flux 65-72%, and material color is pure white, flux recovery after cleaningTo before 95% or more, service phase is 3-5.
Embodiment 3
The polytetrafluoroethyltubular tubular membrane of the present embodiment has the pore structure of three-dimensional perforation, there is transforaminal, hole on the stem of holeLyriform pore diameter is 500nm, stem diameter 260nm, transforaminal aperture 80nm；Wherein the porosity of hole is 60%, and the porosity of transforaminal is52%；The total surface area of the stem, stem area: transforaminal area=20:1.Bore 3mm, thickness of pipe wall 0.6mm.
165 ° of resulting materials hydrophobic angle.Gained PTFE material is subjected to membrane distillation: such as highly concentrated useless containing phenol for hc effluentThe processing of water and highly concentrated brine waste is adapted to industrial excellent properties and effect.As processes composition is complicated, highly concentratedBrine waste (by taking saccharin sodium produces waste water as an example) is spent, Na ion concentration is 3.5g/L, sulfate concentration 8.0g/L, DOC is bigIn 8.0g/L.It can reach discharge standard after processing.Flux of membrane distillation > 20L/m2H, rejection stablize 99% or more, continuously intoRow membrane distillation 3-4 months, flux dropped to former flux 65-72%, and material color is pure white after cleaning, before flux recovery arrives95% or more, service phase is 3-5.