A kind of preparation method of poly tetrafluoroethylene
Technical field
The present invention relates to a kind of preparation method of the diffusion barrier material for separating of field, be specifically related to a kind of preparation method of hydrophobic membrane material.
Technical background
Hydrophobicity is the critical nature of polytetrafluoroethylene (PTFE) (PTFE) material, is the main performance that polytetrafluoroethylporous porous membrane is applied to membrane material.Although polytetrafluoroethylmaterial material has low-surface-energy, the water contact angle of smooth polytetrafluoroethylene (PTFE) plane is between 98 to 112 °, and hydrophobic performance is not good.
Current polytetrafluoroethylporous porous membrane preparation adopts bidirectional extending method more.When this method will expect the film of higher porosity, need to carry out vast scale stretching to film, cannot control by Surface Structures, and thickness is only below tens microns, backing material is needed in using, and backing material itself often has certain limitation in heat resistance or chemical stability or hydrophobic performance, thus limit the application of this biaxial stretching film.Stretch at high proportion simultaneously and be often difficult to the shape of controlling diaphragm, therefore main based on Flat Membrane.The patents such as Chinese patent CN1775847A, CN102007242A, CN101543734B, CN102151494A all carry out polytetrafluoroethylporous porous membrane preparation based on above stretch processes.
The patents such as support methods prepares the important method of polytetrafluoroethylene fibre, CN101994161A and CN102282301A adopt the preparation of electrostatic spinning technique to polytetrafluoroethylsuperfine superfine fiber to report.All relate to the step of high temperature sintering removing fibroblast carrier in these reports, but these sintering processes only pay close attention to the removal of fibroblast template.Specifically: the object of CN101994161A is a kind of polytetrafluoroethylsuperfine superfine fiber of preparation, its preparation method adopts polyvinyl alcohol to make carrier, to be weaved out polytetrafluoroethylene fibre precursor by electrospinning process, post-processing approach is by polytetrafluoroethylene fibre precursor at 100 ~ 120 DEG C dry 5 ~ 15 minutes, then sinters 30 ~ 90 minutes at 280 ~ 350 DEG C; The object of sintering removes to make polyvinyl alcohol decompose.And CN102282301A improving one's methods of a kind of polytetrafluoroethylene (PTFE) pad is mainly provided, its objective is that the technological parameter (spinning fluid viscosity) in order to improve electrospinning obtains the polytetrafluoroethylene fibre pad precursor of uniform diameter, at 400 DEG C, sintering obtains polytetrafluoroethylene fibre pad again, and the ash content of carrier (fibre-forming polymer) is less than 5%.The patents such as CN101994161A and CN102282301A adopt electrostatic spinning technique to polytetrafluoroethylsuperfine superfine fiber (pad), only consider and how to obtain polytetrafluoroethylsuperfine superfine fiber (pad), have to conventional polytetrafluoroethylsuperfine superfine fiber (pad).
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 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 kind of preparation method of poly tetrafluoroethylene, comprise fibroblast carrier system fibre sintering, it is characterized in that: sintering adopts temperature programmed control zonal cooling sintering, under flowing atmosphere, at 90 DEG C ~ 120 DEG C insulation 30 ~ 120min, 260 DEG C ~ 300 DEG C are warmed up to from 90 DEG C ~ 120 DEG C, at 260 DEG C ~ 300 DEG C insulation 30 ~ 120min with the speed of 3 ~ 10 DEG C/min; 370 DEG C ~ 390 DEG C are warmed up to from 260 DEG C ~ 300 DEG C, at 370 DEG C ~ 390 DEG C insulation 5 ~ 120min with the speed of 2 ~ 8 DEG C/min.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.
Preferably, above-mentioned sintering adopts temperature programmed control zonal cooling sintering, under flowing atmosphere, with 2 ~ 15 DEG C/min from room temperature to 90 DEG C ~ 120 DEG C, at 90 DEG C ~ 120 DEG C insulation 50 ~ 100min, 280 DEG C ~ 300 DEG C are warmed up to from 100 DEG C ~ 120 DEG C, at 280 DEG C ~ 300 DEG C insulation 60 ~ 120min with the speed of 5 ~ 8 DEG C/min; 380 DEG C ~ 390 DEG C are warmed up to from 280 DEG C ~ 300 DEG C, at 380 DEG C ~ 390 DEG C insulation 30 ~ 80min with the speed of 4 ~ 7 DEG C/min.
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.
Particularly, a kind of preparation method of poly tetrafluoroethylene, comprises the following steps:
(1) preparation of spinning solution; Be made into water-soluble for water-soluble polymer the homogeneous solution that concentration is 0.5% ~ 30% mass concentration, then stir and add ptfe emulsion, obtain uniform mixed liquor; Fibroblast carrier and polytetrafluoroethylene (PTFE) dry weight ratio are 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, at 90 DEG C ~ 120 DEG C insulation 30 ~ 120min, is warmed up to 260 DEG C ~ 300 DEG C with the speed of 3 ~ 10 DEG C/min from 90 DEG C ~ 120 DEG C, at 260 DEG C ~ 300 DEG C insulation 30 ~ 120min; 370 DEG C ~ 390 DEG C are warmed up to from 260 DEG C ~ 300 DEG C, at 370 DEG C ~ 390 DEG C insulation 5 ~ 120min with the speed of 2 ~ 8 DEG C/min.
Above-mentioned flowing atmosphere is air, nitrogen or inert gas at least one.
Beneficial effect
1. 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 is homogeneous, surface is 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.
Accompanying drawing explanation
Fig. 1 is the scanning electron microscope (SEM) photograph of the poly tetrafluoroethylene that preparation method of the present invention obtains; Can observe from accompanying drawing: poly tetrafluoroethylene of the present invention has by the crisscross hole three-dimensional communication structure formed of beading filament, and hole is hole, labyrinth, even pore distribution is communicated with, and nanofiber form is homogeneous intact.
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 12%, 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, with 10 DEG C/min from room temperature to 110 DEG C, 110 DEG C of insulation 90min, be warming up to 290 DEG C with 7 DEG C/min programming rate from 110 DEG C, 290 DEG C of insulation 100min, are warmed up to 380 DEG C from 290 DEG C, programming rate is 6 DEG C/min, insulation 60min.Extract cylinder supporting die out after taking out after cooling, obtain the cylindric poly tetrafluoroethylene that thickness is 156 μm, cut off and can obtain flat porous membrane.This film hydrophobic contact angle 173 °, porosity 88%, average pore size 0.4 μm, hot strength 495psi, percentage elongation 370%, when operating for Membrane Materials, flux 40L/m
2h, rejection 99.7%.
Embodiment 2
The ptfe emulsion of solid content 60% being added drop-wise to mass fraction is stir in the polyacrylic acid aqueous solution of 9%, 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, with 2 DEG C/min from room temperature to 90 DEG C, 90 DEG C of insulation 120min, be warming up to 260 DEG C with 10 DEG C/min programming rate from 90 DEG C, 260 DEG C of insulation 120min, are warmed up to 375 DEG C from 260 DEG C, programming rate is 8 DEG C/min, insulation 115min.Extract cylinder supporting die out after taking out after cooling, obtain the cylindric poly tetrafluoroethylene that thickness is 165um, cut off and can obtain flat porous membrane.This film hydrophobic contact angle 159 °, porosity 81%, average pore size 0.45 μm, hot strength 460psi, percentage elongation 311%, when operating for Membrane Materials, flux 25L/m
2h, rejection 99.3%.
Embodiment 3
The ptfe emulsion of solid content 60% being added drop-wise to mass fraction is stir in the sodium alginate aqueous 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 5 layers, and deliver to logical nitrogen in tube furnace, sintering process temperature programmed control, with 5 DEG C/min from room temperature to 100 DEG C, 100 DEG C of insulation 110min, be warming up to 275 DEG C with 10 DEG C/min programming rate from 100 DEG C, 275 DEG C of insulation 110min, are warmed up to 380 DEG C from 275 DEG C, programming rate is 3 DEG C/min, insulation 90min.Extract cylinder supporting die out after taking out after cooling, obtain the cylindric poly tetrafluoroethylene that thickness is 171um, cut off and can obtain flat porous membrane.This film hydrophobic contact angle 163 °, porosity 80%, average pore size 0.15 μm, hot strength 465psi, percentage elongation 320%, when operating for Membrane Materials, flux 28L/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 aqueous gelatin solution of 7%, 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 blowing air in tube furnace, sintering process temperature programmed control, with 8 DEG C/min from room temperature to 100 DEG C, 100 DEG C of insulation 100min, be warming up to 280 DEG C with 8 DEG C/min programming rate from 100 DEG C, 280 DEG C of insulation 120min, are warmed up to 385 DEG C from 280 DEG C, programming rate is 4 DEG C/min, insulation 80min.Extract cylinder supporting die out after taking out after cooling, obtain thickness be 215um cylindric poly tetrafluoroethylene, cut off and can obtain flat porous membrane.This film hydrophobic contact angle 165 °, porosity 85%, average pore size 0.45 μm, hot strength 475psi, percentage elongation 323%, when operating for Membrane Materials, flux 30L/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 13%, 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, with 15 DEG C/min from room temperature to 120 DEG C, 120 DEG C of insulation 30min, be warming up to 295 DEG C with 3 DEG C/min programming rate from 120 DEG C, 295 DEG C of insulation 120min, are warmed up to 390 DEG C from 295 DEG C, programming rate is 2 DEG C/min, insulation 10min.Extract cylinder supporting die out after taking out after cooling, obtain the tubular membrane that thickness is 165um.This film hydrophobic contact angle 170 °, porosity 84%, average pore size 0.5 μm, hot strength 470psi, percentage elongation 340%, when operating for tubular membrane Membrane Materials, flux 35L/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 sodium alginate aqueous solution of 8%, 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, with 12 DEG C/min from room temperature to 115 DEG C, 115 DEG C of insulation 50min, be warming up to 300 DEG C with 5 DEG C/min programming rate from 115 DEG C, 300 DEG C of insulation 60min, are warmed up to 390 DEG C from 300 DEG C, programming rate is 6 DEG C/min, insulation 30min.Extract cylinder supporting die out after taking out after cooling, obtain the tubular membrane that thickness is 156um.This film hydrophobic contact angle 174 °, porosity 88%, average pore size 0.35 μm, hot strength 480psi, percentage elongation 355%, when operating for tubular membrane Membrane Materials, flux 37L/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 aqueous gelatin solution of 4%, 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, with 9 DEG C/min from room temperature to 110 DEG C, 110 DEG C of insulation 80min, be warming up to 285 DEG C with 6 DEG C/min programming rate from 110 DEG C, 285 DEG C of insulation 70min, are warmed up to 380 DEG C from 285 DEG C, programming rate is 5 DEG C/min, insulation 60min.Extract cylinder supporting die out after taking out after cooling, obtain the hollow-fibre membrane that thickness is 209um.This film hydrophobic contact angle 175 °, porosity 85%, average pore size 0.4 μm, hot strength 488psi, percentage elongation 364%, during for hollow-fibre membrane distillation procedure, flux 41L/m
2h, rejection 99.9%.