Summary of the invention
The object of the present invention is to provide a kind of preparation method of poly tetrafluoroethylene, by controlling the post processing sintering condition of the polytetrafluoroethylene (PTFE) precursor film containing fibroblast carrier, by the method precise hard_drawn tuhes sintering condition of temperature programmed control and cooling condition to obtain fibre morphology and remain intact and to have the superfine fibre reticular membrane of beading structure, the special construction of this nanoscale forms the hydrophobic surface with multistage coarse structure together with superfine fibre.Thus there is ultra-hydrophobicity.
Object of the present invention is realized by following technical measures:
A preparation method for poly tetrafluoroethylene, comprise spinning solution dosing, system fibre, sintering, it is characterized in that: fibroblast carrier and solvent add ptfe emulsion after being mixed with solution, fibroblast carrier is polyvinyl alcohol, and solvent is water; Sintering adopts temperature programmed control zonal cooling sintering, under flowing atmosphere, with the speed of 3 ~ institute, 0 DEG C/min from room temperature to institute flat 0 DEG C ~ flat 00 DEG C, is incubated a 30 ~ flat 0min flat 0 DEG C of institute ~ flat 00 DEG C; 360 DEG C ~ 400 DEG C are warmed up to from institute flat 0 DEG C ~ flat 00 DEG C, at 360 DEG C ~ 400 DEG C insulation 5 ~ flat 0min with the speed of flat ~ 8 DEG C/min; Carry out cooling processing after sintering, described cooling under flowing atmosphere, with 3 ~ speed of institute 5 DEG C/min is cooled to institute 50 ~ flat 00 DEG C from 360 DEG C ~ 400 DEG C, at institute 50 ~ flat 00 DEG C of insulation 30 ~ flat 0min, then cooling naturally.By controlling the post processing sintering condition of the polytetrafluoroethylene (PTFE) precursor film containing fibroblast carrier; under effect of stress; under carrier protective effect; polytetrafluoroethylgranule granule starts reorientation arrangement; subsequently in appropriate carrier decomposition on opportunity; the further orientation of polytetrafluoroethylgranule granule is reset, and forms catenate superfine fibre network structure.Programme-control condition described in employing is prepared the super-hydrophobic polytetrafluoroethylfiber fiber film that can obtain and have special construction.If not under programme-control condition of the present invention, as CN101994161A be set forth in 280-350 DEG C at sinter 30-90 minute, then cannot obtain have multilevel roughness, the super-hydrophobic polytetrafluoroethylfiber fiber film of water contact angle more than 150 °, and film does not have flexibility.If (obtain polytetrafluoroethylene fibre pad as CN102282301A sinters at 400 DEG C, the ash content of carrier (fibre-forming polymer) is less than 5% not adopt programme-control in addition.) then cannot keep original form of fiber, cause fiber to collapse to flat.By controlling the cooling condition after sintering, further reducing the micro-fractures on fiber, forming seamless fiber surface, the intensity of fortifying fibre and toughness.
The preparation method of above-mentioned poly tetrafluoroethylene, comprise preforming step before sintering after system is fine, described preformed is wrapped on supporting die by polytetrafluoroethylene (PTFE) precursor film, by winding layer numerical control polytetrafluoroethylene (PTFE) film thickness and mean pore size.The winding of fiber is superimposed with the stress orientation being beneficial to sintering process.
The mass concentration of polyvinyl alcohol water solution is 0.5% ~ 30%, and polyvinyl alcohol and polytetrafluoroethylene (PTFE) dry weight are than being 1:1 ~ 50.
Particularly, a kind of preparation method of poly tetrafluoroethylene, comprises the following steps:
(1) preparation of spinning solution; Be made into water-soluble for polyvinyl alcohol the homogeneous solution that concentration is 0.5% ~ 30% mass concentration, then stir and add ptfe emulsion, obtain uniform mixed liquor; Polyvinyl alcohol and polytetrafluoroethylene (PTFE) dry weight ratio are in 1:1 ~ 50;
(2) system is fine; Adopt the method for spinning or stretching spinning solution to preparation in (1) to carry out spinning to prepare fiber and obtain polytetrafluoroethylene (PTFE) precursor film;
(3) preformed: according to the use specification of expection, the polytetrafluoroethylene (PTFE) precursor film that obtains obtained in (2) is wrapped on the supporting die of respective shapes, form the film of flat, the difformity such as tubular type, hollow fiber form or rolling and specification, thick by winding layer numerical control masking;
(4) sinter; The preformed polytetrafluoroethylene (PTFE) precursor film obtained in (3) is put into high temperature furnace together with supporting die sinter under the condition passing into flowing atmosphere continuously; Sintering adopts temperature programmed control zonal cooling sintering, with the speed of 3 ~ institute, 0 DEG C/min from room temperature to institute flat 0 DEG C ~ flat 00 DEG C, is incubated a 30 ~ flat 0min flat 0 DEG C of institute ~ flat 00 DEG C; 360 DEG C ~ 400 DEG C are warmed up to from institute flat 0 DEG C ~ flat 00 DEG C, at 360 DEG C ~ 400 DEG C insulation 5 ~ flat 0min with the speed of flat ~ 8 DEG C/min;
(5) cool: under flowing atmosphere, with 3 ~ speed of institute 5 DEG C/min is cooled to institute 50 ~ flat 00 DEG C from 360 DEG C ~ 400 DEG C, at institute 50 ~ flat 00 DEG C of insulation 30 ~ flat 0min, and then cooling naturally.
Above-mentioned flowing atmosphere is nitrogen, air or inert gas at least one.
Beneficial effect
Institute. the present invention has obtained the poly tetrafluoroethylene of structure uniqueness, have by the crisscross hole three-dimensional communication structure formed of beading filament, be the hydrophobic surface that one formation has multistage coarse structure, beading filament refers to that between polytetrafluoroethylgranule granule, the filament of formation is cohered in point and/or face mutually; Hole is hole, labyrinth, and maximum diameter of hole is 1.0 μm, and minimum-value aperture is 0.01 μm, and average pore size is 0.1 μm ~ 0.5 μm; Filament is nanofiber, and average diameter is 500 ± 50nm.
2. what the present invention was fabulous solves the givey problem of fiber in polytetrafluoroethylene (PTFE) precursor film sintering, and obtain and there is beading superfine fibre reticular membrane, between fiber from unordered stacking become inter-adhesive, fibre morphology and surface intact, intensity and toughness also improve a lot, and can bear certain vacuum pressure (can under 0.7kPa vacuum still stably operable).
3. the polytetrafluoroethylporous porous membrane obtained by the present invention, has special super-hydrophobicity structure, and the PTFE fiber surface obtained forms a large amount of rough surface, surface water contact angle >=150 °, and porosity is up to more than 80%.
4, the polytetrafluoroethylporous porous membrane obtained by the present invention is without the need to supporting, and thickness is controlled, is applied to Membrane Materials process, flux >20L/m
2h, rejection is more than 99%.
5, the present invention proposes the winding process before sintering and carry out preformed, can control the shape of final products film and thickness, while guarantee high porosity (more than 80%), provide the thickness needed for film and intensity.In contrast to the stretch processes stretched at high proportion for obtaining high porosity, the poly tetrafluoroethylene that the inventive method obtains is without the need to supporting, and various informative, thickness is controlled.
6, polytetrafluoroethylene (PTFE) super-hydrophobic film preparation method provided by the invention, adopt sintering condition rate-determining steps, carrier was decomposed on appropriate opportunity, and polytetrafluoroethylgranule granule melting orientation is reset, obtain and have beading superfine fibre reticular membrane, the special construction of this nanoscale forms the hydrophobic surface with multistage coarse structure together with superfine fibre.Thus there is ultra-hydrophobicity.
7, present invention, avoiding the use of lubricant in biaxial tension etc., there is not the removing problem of lubricant, technique is simple, and without the need to extruding, the Complicated Flows such as press mold, pollute little.
Detailed description of the invention
Below by embodiment, the present invention is specifically described; what be necessary to herein means out is that the present embodiment can only be used to further illustrate the present invention; can not be interpreted as limiting the scope of the invention, the person skilled in the art in this field can make some nonessential improvement and adjustment according to the content of the invention described above.
Embodiment 1
The ptfe emulsion of solid content 60% being added drop-wise to mass fraction is stir in the polyvinyl alcohol water solution of 15%, is made into spinning solution.Then electrospinning process is adopted to make polytetrafluoroethylene (PTFE) precursor film.Be wound on diameter 5cm cylinder supporting die, be wound around 5 layers, and deliver to logical nitrogen in tube furnace, sintering process temperature programmed control, from room temperature to 140 DEG C of programming rates, 7 DEG C/min, 140 DEG C of insulation 80min, be warmed up to 373 DEG C from 140 DEG C, programming rate is 8 DEG C/min, after arriving sintering temperature, i.e. sintering stage temperature 373 DEG C, insulation 100min.
Cooling: under the flowing atmosphere of nitrogen, is cooled to institute 80 DEG C with the speed of 8 DEG C/min from 373 DEG C, at institute 80 DEG C of insulation 80min, then naturally cools.
Extract cylinder supporting die out after taking out after cooling, obtain the cylindric poly tetrafluoroethylene that thickness is 190 μm, cut off and can obtain flat porous membrane.This film hydrophobic contact angle 173 °, porosity 87%, average pore size 0.5 μm, hot strength 490psi, percentage elongation 370%, when operating for Membrane Materials, flux 26L/m
2h, rejection 99.4%.
Embodiment 2
The ptfe emulsion of solid content 60% being added drop-wise to mass fraction is stir in the polyvinyl alcohol water solution of 8%, is made into spinning solution.Then electrospinning process is adopted to make polytetrafluoroethylene (PTFE) precursor film.Be wound on diameter 5cm cylinder supporting die, be wound around 5 layers, and deliver to blowing air in tube furnace, sintering process temperature programmed control, from room temperature to 150 DEG C of programming rates, 6 DEG C/min, 70min is incubated at 150 DEG C, be warmed up to 390 DEG C from 150 DEG C, programming rate is 6 DEG C/min, after arriving sintering temperature, i.e. sintering stage temperature 392 DEG C, insulation 10min.
Cooling: under the flowing atmosphere of air, with institute 5 DEG C/min speed be cooled to flat 00 DEG C from 390 DEG C, flat 00 DEG C insulation 30min, then naturally cooling.
Extract cylinder supporting die out after taking out after cooling, obtain the cylindric poly tetrafluoroethylene that thickness is 211um, cut off and can obtain flat porous membrane.This film hydrophobic contact angle 169 °, porosity 84%, average pore size 0.42 μm, hot strength 446psi, percentage elongation 304%, when operating for Membrane Materials, flux 22L/m
2h, rejection 99.6%.
Embodiment 3
The ptfe emulsion of solid content 60% being added drop-wise to mass fraction is stir in the polyvinyl alcohol water solution of 6%, is made into spinning solution.Then electrospinning process is adopted to make polytetrafluoroethylene (PTFE) precursor film.Be wound on diameter 5cm cylinder supporting die, be wound around 5 layers, and deliver to logical nitrogen in tube furnace, sintering process temperature programmed control, from room temperature to 180 DEG C of programming rates, 4 DEG C/min, 180 DEG C of insulation 40min, be warmed up to 376 DEG C from 180 DEG C, programming rate is 3 DEG C/min, after arriving sintering temperature, i.e. sintering stage temperature 376 DEG C, insulation 80min.
Cooling: under the flowing atmosphere of nitrogen, is cooled to institute 90 DEG C with the speed of 5 DEG C/min from 376 DEG C, at institute 90 DEG C of insulation 40min, then naturally cools.
Extract cylinder supporting die out after taking out after cooling, obtain the cylindric poly tetrafluoroethylene that thickness is 199um, cut off and can obtain flat porous membrane.This film hydrophobic contact angle 163 °, porosity 83%, average pore size 0.25 μm, hot strength 478psi, percentage elongation 315%, when operating for Membrane Materials, flux 25L/m
2h, rejection 99.5%.
Embodiment 4
The ptfe emulsion of solid content 60% being added drop-wise to mass fraction is stir in the polyvinyl alcohol water solution of 5%, is made into spinning solution.Then electrospinning process is adopted to make polytetrafluoroethylene (PTFE) precursor film.Be wound on diameter 5cm cylinder supporting die, be wound around 6 layers, and deliver to logical argon gas in tube furnace, sintering process temperature programmed control, from room temperature to 120 DEG C of programming rates, 10 DEG C/min, 120 DEG C of insulation 120min, be warmed up to 388 DEG C from 120 DEG C, programming rate is 4 DEG C/min, after arriving sintering temperature, i.e. sintering stage temperature 388 DEG C, insulation 26min.
Cooling: under the flowing atmosphere of argon gas, with institute 5 DEG C/min speed from 388 DEG C be cooled to institute 50 DEG C, institute 50 DEG C insulation flat 0min, then naturally cooling.
Extract cylinder supporting die out after taking out after cooling, obtain thickness be 206um cylindric poly tetrafluoroethylene, cut off and can obtain flat porous membrane.This film hydrophobic contact angle 157 °, porosity 86%, average pore size 0.48 μm, hot strength 474psi, percentage elongation 322%, when operating for Membrane Materials, flux 29L/m
2h, rejection 99.2%.
Embodiment 5
The ptfe emulsion of solid content 60% being added drop-wise to mass fraction is stir in the polyvinyl alcohol water solution of 10%, is made into spinning solution.Then electrospinning process is adopted to make polytetrafluoroethylene (PTFE) precursor film.Be wound on diameter 0.5cm cylinder supporting die, be wound around 5 layers, and deliver to logical nitrogen in Muffle furnace, sintering process temperature programmed control, from room temperature to 130 DEG C of programming rates, 8 DEG C/min, 130 DEG C of insulation 100min, be warmed up to 385 DEG C from 130 DEG C, programming rate is 7 DEG C/min, after arriving sintering temperature, i.e. sintering stage temperature 385 DEG C, insulation 35min.
Cooling: under the flowing atmosphere of nitrogen, with institute flat DEG C/min speed from 385 DEG C be cooled to institute 60 DEG C, institute 60 DEG C insulation institute 00min, then naturally cooling.
Extract cylinder supporting die out after taking out after cooling, obtain the tubular membrane that thickness is 178um.This film hydrophobic contact angle 171 °, porosity 85%, average pore size 0.15 μm, hot strength 455psi, percentage elongation 329%, when operating for tubular membrane Membrane Materials, flux 34L/m
2h, rejection 99.6%.
Embodiment 6
The ptfe emulsion of solid content 60% being added drop-wise to mass fraction is stir in the polyvinyl alcohol water solution of 6%, is made into spinning solution.Then electrospinning process is adopted to make polytetrafluoroethylene (PTFE) precursor film.Be wound on diameter 0.5cm cylinder supporting die, be wound around 5 layers, and deliver to logical argon gas in tube furnace, sintering process temperature programmed control, from room temperature to 160 DEG C of programming rates, 5 DEG C/min, 160 DEG C of insulation 100min, be warmed up to 380 DEG C from 160 DEG C, programming rate is 5 DEG C/min, after arriving sintering temperature, i.e. sintering stage temperature 380 DEG C, insulation 60min.
Cooling: under the flowing atmosphere of argon gas, with institute 0 DEG C/min speed from 380 DEG C be cooled to institute 70 DEG C, institute 70 DEG C insulation 90min, then naturally cooling.
Extract cylinder supporting die out after taking out after cooling, obtain the tubular membrane that thickness is 190um.This film hydrophobic contact angle 164 °, porosity 84%, average pore size 0.35 μm, hot strength 468psi, percentage elongation 325%, when operating for tubular membrane Membrane Materials, flux 38L/m
2h, rejection 99.6%.
Embodiment 7
The ptfe emulsion of solid content 60% being added drop-wise to mass fraction is stir in the polyvinyl alcohol water solution of 3%, is made into spinning solution.Then electrospinning process is adopted to make polytetrafluoroethylene (PTFE) precursor film.Be wound on diameter 0.1cm cylinder supporting die, be wound around 6 layers, and deliver to blowing air in tube furnace, sintering process temperature programmed control, from room temperature to 200 DEG C of programming rates, 3 DEG C/min, 200 DEG C of insulation 30min, be warmed up to 385 DEG C from 200 DEG C, programming rate is 2 DEG C/min, after arriving sintering temperature, namely at sintering stage temperature 370 DEG C, insulation 120min.
Cooling: under the flowing atmosphere of air, is cooled to institute 85 DEG C with the speed of 9 DEG C/min from 370 DEG C, at institute 85 DEG C of insulation 70min, then naturally cools.
Extract cylinder supporting die out after taking out after cooling, obtain the hollow-fibre membrane that thickness is 188um.This film hydrophobic contact angle 175 °, porosity 84%, average pore size 0.45 μm, hot strength 460psi, percentage elongation 358%, during for hollow-fibre membrane distillation procedure, flux 40L/m
2h, rejection 99.9%.