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, hole aperture on the stem of holeFor 800 ± 200nm, stem diameter is 500 ± 100nm, 175 ± 25nm of transforaminal aperture；Wherein the porosity of hole is 80 ± 10%,The porosity of transforaminal is 30 ± 15%；The total surface area of the stem, stem area: transforaminal area=16-30:1；Bore is greater than 2mm,Thickness of pipe wall is not less than 0.1mm.The film is during the Selective Separation for substance, when one such or different kinds of molecules existsWhen by material surface and/or inside, the microstructure of molecule will receive itself and the effect of material and the influence of bond structure, fromAnd the percent of pass and throughput of substance are affected, the microstructure of another aspect material also will receive influence, to influence materialSeparation tower, service phase etc..So both ensure that separate substance by efficiency and throughput, combine the use of materialRate.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 700-800nm, stem diameter 450-510nm, transforaminal aperture 155-175nm；Wherein the porosity of hole is 80-85%, the hole of transforaminalRate is 16-20%；The total surface area of the stem, stem area: transforaminal area=20-25:1.
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: the gelatin homogeneous solution soluble in water for obtaining 14-15% concentration, and polytetrafluoroethylene (PTFE) cream is addedLiquid (55-60%), so that PTFE and gelatin 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. being filled with nitrogen to pressure value in 120-180s is greater than 70kpa no more than 75kpa, while with 4-5 DEG C/minTemperature value is warming up to greater than 380 DEG C no more than 385 DEG C, and is greater than 70kpa in pressure value and is greater than 380 no more than 75kpa, temperature valueDEG C no more than keeping 8-12min at 385 DEG C；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, there is transforaminal, hole on the stem of holeLyriform pore diameter is 800 ± 200nm, and stem diameter is 500 ± 100nm, 175 ± 25nm of transforaminal aperture；Wherein the porosity of hole is 80± 10%, the porosity of transforaminal is 30 ± 15%；The total surface area of the stem, stem area: transforaminal area=16-30:1.Bore is bigIt is less than 50mm, thickness of pipe wall 0.15-2mm in 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: the gelatin homogeneous solution soluble in water for obtaining 14-15% concentration, and polytetrafluoroethylene (PTFE) cream is addedLiquid (55-60%), so that PTFE and gelatin 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 be wrapped in outer diameter greater than 2mm be less than 50mm cylinder branch hold mode on form tubular typeForm；
(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. being filled with nitrogen to pressure value in 120-180s is greater than 70kpa no more than 75kpa, while with 4-5 DEG C/minTemperature value is warming up to greater than 380 DEG C no more than 385 DEG C, and is greater than 70kpa in pressure value and is greater than 380 no more than 75kpa, temperature valueDEG C no more than keeping 8-12min at 385 DEG C；3. after heating, keeping vacuum to cooling to 50-100Pa.
154-175 ° of resulting materials hydrophobic angle.Gained PTFE material is subjected to membrane distillation: for the processing of watermelon juice, being hadIt is adapted to industrial excellent properties and effect.Can not damage nutriment (such as vitamin C, total acid, TSS) obtain it is highly concentratedContracting fruit juice.Flux of membrane distillation > 20L/m2H, rejection are stablized 99% or more, membrane distillation are carried out continuously 3-5 months, under fluxIt is down to former flux 68-75%, material color is pure white after cleaning, and for flux recovery before 95% or more, service phase is 3-5Year.
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 700-800nm, stem diameter 450-510nm, transforaminal aperture 155-175nm；Wherein the porosity of hole is 80-85%, the porosity of transforaminal is 16-20%；The total surface area of the stem, stem area: transforaminal area=20-25:1.Bore is greater than2mm is less than 50mm, thickness of pipe wall 0.15-2mm.
157-175 ° of resulting materials hydrophobic angle.Gained PTFE material is subjected to membrane distillation: for the processing of watermelon juice, being hadIt is adapted to industrial excellent properties and effect.Can not damage nutriment (such as vitamin C, total acid, TSS) obtain it is highly concentratedContracting fruit juice.Flux of membrane distillation > 20L/m2H, rejection are stablized 99% or more, membrane distillation are carried out continuously 3-5 months, under fluxIt is down to former flux 68-75%, material color is pure white after cleaning, and for flux recovery before 95% or more, service phase is 3-5Year.
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 750nm, stem diameter 450nm, transforaminal aperture 155nm；Wherein the porosity of hole is 80%, the porosity of transforaminalIt is 18%；The total surface area of the stem, stem area: transforaminal area=22:1.Bore 10mm, thickness of pipe wall 1mm.
159 ° of resulting materials hydrophobic angle.Gained PTFE material is subjected to membrane distillation: for the processing of watermelon juice, there is adaptationIn industrial excellent properties and effect.Nutriment (such as vitamin C, total acid, TSS) can not be damaged and obtain highly enriched fruitJuice.Flux of membrane distillation > 20L/m2H, rejection are stablized 99% or more, are carried out continuously membrane distillation 3-5 months, flux drops toFormer flux 68-75%, material color is pure white after cleaning, and for flux recovery before 95% or more, service phase is 3-5.