Ion-exchange membrane moving under a kind of super high current densities and preparation method thereof
Technical field
The present invention relates to the ion-exchange membrane moving under a kind of super high current densities, belong to field of functional polymer composites.
Background technology
In chlorine industry, divide according to the current density of operation, ion-exchange membrane electrolyzer can be divided into high current density electrolysis groove and general current density electrolyzer.The stagnation point of the two is set as 4.0KA/m conventionally
2.The current density of traditional ion-exchange membrane electrolyzer operation is 3.3KA/m
2left and right, and the current density of high current density ion-exchange membrane electrolyzer operation is generally 4.0-6.0KA/m
2or higher.
Comparatively speaking, the operation of high current density electrolysis groove has following advantage: 1) can strengthen throughput, as 4.2KA/m
2the electrolyzer moving under condition is than 3.3KA/m
2the electrolyzer moving under condition improves caustic soda production approximately 27.3%; 2) can reduce the one-time investment of ion film caustic soda project; 3) floor space of saving project, the management after the project of being convenient to is built up; 4) turndown ratio is large, is conducive to reduce running cost.But, under high current densities, move except optimizing electrolyzer material and structure, Optimizing operation technique and technical indicator, optimization brine quality, also need the ion-exchange membrane moving under the corresponding high current densities of adapted.This film is different from the ionic membrane moving under general current density condition, because the current density of high current density electrolysis groove operation improves, must improve the flow that the unit time enters electric groove salt solution, this just requires ion-exchange membrane to have stronger ion-exchange capacity, within the unit time, allows more Na ion enter cathode compartment by anolyte compartment through ion-exchange membrane.
Patent ZL200720010486.2 discloses the high current density expansion anode electrolysis slot that a kind of chlor-alkali industry uses, and is to realize electrolysis safe and stable operation under high current density from the improvement of cell construction; According to chlor-alkali industry data report, thereby the ion-exchange membrane of external high current density of new generation adopts thinner thicknesses of layers and thinner fortifying fibre to reduce stops area, improve flux, and effect is obvious, but film strength decline is a lot, the lost of life; Patent US2005/0279644A1 discloses a kind of electrolysis with ion-exchange film technique, can make ionic membrane adapt to the steady running under different current density conditions, but also just realizes by the adjustment of ionic membrane and anode spacing, and current density is only brought up to 7KA/m
2.As a rule, in order to improve the ionic flux of ion-exchange membrane, the most succinct method is to adopt the sulfonic acid of high-exchange-capacity or carboxylic acid resin to prepare the ionic membrane of high-exchange-capacity, but the exchange capacity that there will be carboxylic acid in actual preparation and application process cathode side that is too high and that cause declines to barrier property hydroxy, causes the hydrogen in chlorine excessive; And the exchange capacity that improves separately sulfonic acid exists and does not mate with carboxylic acid resin and the easy defect of layering.
Summary of the invention
For the deficiencies in the prior art, the invention provides ion-exchange membrane moving under a kind of super high current densities and preparation method thereof, this film is higher than 4.0-6.0KA/m
2current density condition under, even exceed 8KA/m
2superelevation current density under, can show extraordinary bath voltage and current efficiency advantage, guaranteed film toughness simultaneously.
Terminological interpretation:
Superelevation current density, belongs to the conventional saying of one under chlor-alkali industry specific environment, and the current density of traditional ion-exchange membrane electrolyzer operation is 3.3KA/m
2left and right, the current density of high current density ion-exchange membrane electrolyzer operation is generally 4.0-6.0KA/m
2, the so-called superelevation current density of the present invention refers to the current density of electrolyzer operation higher than 6.0KA/m
2.But under super high current densities of the present invention, operation is not limited only to current density higher than 6.0KA/m
2, be also suitable for moving 4.0-6.0KA/m under high current densities
2.
Technical scheme of the present invention is as follows:
The ion-exchange membrane moving under super high current densities, perfluorinated carboxylic acid resin's film that this ion-exchange membrane is is the high-elastic film of low-molecular-weight perfluor hotmelt of 1~30 micron and low ion exchange capacity by perfluorinated sulfonic resin film, the thickness of high-exchange-capacity successively forms the composite membrane of three-decker.
Wherein, the high-elastic film of described perfluor hotmelt be with the cast of perfluor hotmelt melts, extrude, hot pressing, spin coating, curtain coating or spraying coating process prepare film forming;
Described perfluor hotmelt is terpolymer, and molecular weight, between 1~100,000, has the molecular structure shown in following formula I, and has-SO
2the functional stable end groups of F, wherein m=6~12; N=6~12.
In formula I, preferably m=8, n=8, m=8, n=10, m=7, n=8, m=6, n=12, the combination of m=12, n=10 or m=12, n=12.
According to the present invention, preferred, the described high-elastic film of perfluor hotmelt has ion exchanging function, and loading capacity is between 0.8~1.8mmol/g.
According to the present invention, perfluorinated sulfonic resin film one side of described ion-exchange membrane also hot pressing has fibrous reticulum or microporous membrane, forms enhancement type ion-exchange membrane.
According to the present invention, the exchange capacity of the perfluorinated sulfonic resin film of described high-exchange-capacity is greater than 1.0mmol/g.Preferably, the exchange capacity of the perfluorinated sulfonic resin film of described high-exchange-capacity is 1.0~1.8mmol/g.High-exchange-capacity can improve the Flux in ion unit surface, can allow film to move under high current densities.
According to the present invention, the perfluorinated sulfonic resin film thickness of described high-exchange-capacity is between 40~200 μ m, and preferred, the perfluorinated sulfonic resin film thickness of described high-exchange-capacity is 80~120 microns; Selected thickness can guarantee film toughness, can not increase because of the thickness of film again membrane resistance.
According to the present invention, the described high-elastic film of low-molecular-weight perfluor hotmelt, adopts perfluor hotmelt to be prepared from.Described perfluor hotmelt has the structure shown in formula I, molecular weight is between 1~100,000, perfluor tackiness agent in this molecular weight ranges has good elasticity and swelling property, can between high-exchange-capacity sulfonate film and low ion exchange capacity carboxylic acid membrane, form transition layer, alleviate the distortion that the two swelling property difference causes greatly and peel off.
Described perfluor hotmelt has fusible characteristic, in the temperature range of 100~200 ℃, the viscosity of melt is 200~700cp, this characteristic makes this tackiness agent directly melting curtain coating to be coated in perfluorinated sulfonic resin film surface, after using dissolution with solvents, apply, environmental protection and operating procedure are simple.
According to the present invention, preferred, the described high-elastic film thickness of perfluor hotmelt is 2~10 microns, the too thick intensity that can affect film body of binder layer.
Perfluorinated carboxylic acid resin's film of described low ion exchange capacity, its exchange capacity is between 0.7~1.0mmol/g, and the too high meeting of this rete exchange capacity causes the hydroxide radical blocking effect variation of film, and current efficiency reduces.
The above-mentioned low perfluorinated carboxylic acid resin's film thickness that changes capacity is between 1~50 μ m, and preferred, the low perfluorinated carboxylic acid resin's film thickness that changes capacity is between 5~20 microns.Described specific thickness can well stop hydroxide radical backmigration, and can not have too many impact to bath voltage.
The ion-exchange membrane moving under described a kind of super high current densities, can adopt fibrous reticulum or microporous membrane to strengthen, strongthener material can be selected from polytetrafluoroethylene (PTFE), high fluothane Vinyl Ether (PFA), perfluoroethylene-propylene (FEP), polyether-ether-ketone (PEEK) etc.
Perfluorinated sulfonic resin of the present invention and perfluorinated carboxylic acid resin are prior art, have the general structure shown in following formula II:
In formula II: M is functional group-SO
2f or-COOCH
3, x=2~10, y=1, n=0 or 1, m=1~5; When M is-SO
2f represents perfluorinated sulfonic resin, and M is-COOCH
3represent perfluorinated carboxylic acid resin, be short chain resin in the time of n=0, is long-chain resin when n=1.
According to the present invention, the preparation method of the ion-exchange membrane moving under described a kind of super high current densities, comprises that step is as follows:
First, adopt the method melt extruding to prepare perfluorinated sulfonic resin monofilm and perfluorinated carboxylic acid resin's monofilm;
Secondly, perfluor hotmelt, by after forcing machine melting, is coated in melt to a surface of perfluorinated sulfonic resin monofilm by curtain coating head direct curtain coating under the support that applies platform, forms the high-elastic rete of perfluor tackiness agent;
Then, when coated with adhesive layers, perfluorinated carboxylic acid resin's film is covered to high-elastic film surface, be combined with each other and form the composite membrane of three-decker by the effect of pressing.Be ion-exchange membrane of the present invention.
Further, optionally, fibrous reticulum or microporous membrane are pressed into perfluorinated sulfonic resin film one side of three-decker composite membrane by the mode of hot pressing, must form enhancement type ion-exchange membrane.
The ion-exchange membrane moving under described a kind of super high current densities, for chloric alkali electrolysis device, at 6-20KA/m
2current density condition under operating performance excellence, especially in current density higher than 8KA/m
2effect is more excellent.
The present invention has following positively effect compared to existing technology:
1, perfluorinated sulfonic resin film widely different exchange capacity and perfluorinated carboxylic acid resin's film are sticked together, make ionic membrane have high loading capacity and the good barrier property of hydroxide radical of sodium ion concurrently, be suitable for moving under high current densities;
2, the high-elastic film of perfluor hotmelt has good deformability under Minimal Tension condition, can make the stripping strength between perfluorinated sulfonic resin film and perfluorinated carboxylic acid resin's film be greater than 40N/cm, and peeling resistance is more excellent, longer service life;
3, the introducing of the high-elastic film of perfluor hotmelt has increased the snappiness of ionic membrane entirety, and anti tear, shock resistance obviously improve.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of ion-exchange membrane three-decker of the present invention, in figure, and 1, perfluorinated sulfonic resin film, 2, the high-elastic film of perfluor hotmelt, 3, perfluorinated carboxylic acid resin's film, 4, fortifying fibre net.
Fig. 2 is three layers of complex flow process schematic representation of ion-exchange membrane of the present invention.In figure, 5 for sulfonate film unreels, the 6 perfluorinated sulfonic resin monofilms of making for forcing machine melting curtain coating, and 7 is curtain coating head, 8 for applying platform, 9 is the high-elastic film of perfluor tackiness agent, and 10 is high temperature pressure roller, and 11 unreel for carboxylic acid membrane, 12 perfluorinated carboxylic acid resin's monofilms of making for forcing machine melting curtain coating, 13 is cooling air device, 14 composite membranes that are three-decker, and 15 is the rolling of composite membrane finished film.
Embodiment
The present invention will now be described in further detail by the embodiment, but be not limited to this.Raw material in embodiment is all prior art material, can buy in market.
Embodiment 1
By the perfluorinated sulfonic resin of IEC=1.4mmol/g, (in formula II, M is-SO
2f, x=2.9, n=1, m=3) form perfluorinated sulfonic resin monofilm, 100 microns of thickness by forcing machine melting curtain coating; By the perfluorinated carboxylic acid resin of IEC=0.95mmol/g, (in formula II, M is-COOCH
3, x=6.3, n=1, m=3) and form perfluorinated carboxylic acid resin's monofilm, 15 microns of thickness by forcing machine melting curtain coating; Then the perfluor hotmelt of molecular weight=7.8 ten thousand, IEC=1.23mmol/g (m=8, n=10 in formula I) is coated at 155 ℃ to a surface of perfluorinated sulfonic resin monofilm after melting by curtain coating head by forcing machine, form the high-elastic rete of perfluor tackiness agent, 5 microns of thickness; Perfluorinated carboxylic acid resin's monofilm is introduced, pressing forms the composite membrane of the three-decker of three-decker together simultaneously; Finally, by the perfluorinated sulfonic resin layer hot pressing of PTFE fibrous reticulum and composite membrane, form the ion-exchange membrane moving under the super high current densities of enhancement type.
This enhancing composite membrane is hydrolyzed 10-15 hour and makes the transition processing, then double-face spray painting zirconia coating in the 25wt%KOH aqueous solution of 90 ℃; The enhancing composite membrane of handling well is arranged in zero pole span test-type electrolyzer and carries out performance test; Probe temperature is 80 ℃, and NaOH concentration of polymer solution is 30%, and current density is 6kA/m
2.Through the electrolytic experiment of 22 days, electrical performance data is stable, average groove is pressed as 2.71V, mean current efficiency is 99.5%, the resistance to tearing that records film according to the method in GB GB/T 16578.2 is 46N, the folding endurance that records film according to the method in GB GB/T 457 is 3.1, and the bursting strength that records film according to the method in GB GB/T454 is 1.3MPa.
Embodiment 2
By the perfluorinated sulfonic resin of IEC=1.15mmol/g, (in formula II, M is-SO
2f, x=5.1, n=0, m=5) form perfluorinated sulfonic resin monofilm, 120 microns of thickness by forcing machine melting curtain coating; By the perfluorinated carboxylic acid resin of IEC=0.75mmol/g, (in formula II, M is-COOCH
3, x=8.7, n=1, m=3) and form perfluorinated carboxylic acid resin's monofilm, 8 microns of thickness by forcing machine melting curtain coating; Then the perfluor hotmelt of molecular weight=5.4 ten thousand, IEC=1.1mmol/g (m=8, n=8 in formula I) is coated at 175 ℃ to a surface of perfluorinated sulfonic resin monofilm after melting by curtain coating head by forcing machine, form the high-elastic rete of perfluor tackiness agent, 8 microns of thickness; Perfluorinated carboxylic acid resin's monofilm is introduced, pressing forms the composite membrane of the three-decker of three-decker together simultaneously; Finally, by the perfluorinated sulfonic resin layer hot pressing of PTFE porous-film and composite membrane, form the ion-exchange membrane moving under the super high current densities of enhancement type.
This enhancing composite membrane is hydrolyzed 10-15 hour and makes the transition processing, then double-face spray painting zirconia coating in the 25wt%KOH aqueous solution of 90 ℃; The enhancing composite membrane of handling well is arranged in zero pole span test-type electrolyzer and carries out performance test; Probe temperature is 80 ℃, and NaOH concentration of polymer solution is 30%, and current density is 8kA/m
2.Through the electrolytic experiment of 42 days, electrical performance data is stable, average groove is pressed as 2.77V, mean current efficiency is 99.6%, the resistance to tearing that records film according to the method in GB GB/T 16578.2 is 48N, the folding endurance that records film according to the method in GB GB/T 457 is 3.3, and the bursting strength that records film according to the method in GB GB/T454 is 1.5MPa.
Embodiment 3
By the perfluorinated sulfonic resin of IEC=1.55mmol/g, (in formula II, M is-SO
2f, x=2.1, n=0, m=3) form perfluorinated sulfonic resin monofilm, 70 microns of thickness by forcing machine melting curtain coating; By the perfluorinated carboxylic acid resin of IEC=0.85mmol/g, (in formula II, M is-COOCH
3, x=6.7, n=0, m=3) and form perfluorinated carboxylic acid resin's monofilm, 10 microns of thickness by forcing machine melting curtain coating; Then the perfluor hotmelt of molecular weight=9.0 ten thousand, IEC=1.3mmol/g (m=7, n=8 in formula I) is coated at 145 ℃ to a surface of perfluorinated sulfonic resin monofilm after melting by curtain coating head by forcing machine, form the high-elastic rete of perfluor tackiness agent, 4 microns of thickness; Perfluorinated carboxylic acid resin's monofilm is introduced, pressing forms the composite membrane of the three-decker of three-decker together simultaneously; Finally, by the perfluorinated sulfonic resin layer hot pressing of PFA fibrous reticulum and composite membrane, form the ion-exchange membrane moving under the super high current densities of enhancement type.
This enhancing composite membrane is hydrolyzed 10-15 hour and makes the transition processing, then double-face spray painting zirconia coating in the 25wt%KOH aqueous solution of 90 ℃; The enhancing composite membrane of handling well is arranged in zero pole span test-type electrolyzer and carries out performance test; Probe temperature is 80 ℃, and NaOH concentration of polymer solution is 30%, and current density is 10kA/m
2.Through the electrolytic experiment of 30 days, electrical performance data is stable, average groove is pressed as 2.65V, mean current efficiency is 99.6%, the resistance to tearing that records film according to the method in GB GB/T 16578.2 is 40N, the folding endurance that records film according to the method in GB GB/T 457 is 2.9, and the bursting strength that records film according to the method in GB GB/T454 is 1.2MPa.
Embodiment 4
By the perfluorinated sulfonic resin of IEC=1.70mmol/g, (in formula II, M is-SO
2f, x=2.1, n=1, m=5) form perfluorinated sulfonic resin monofilm, 150 microns of thickness by forcing machine melting curtain coating; By the perfluorinated carboxylic acid resin of IEC=1.00mmol/g, (in formula II, M is-COOCH
3, x=4.6, n=1, m=3) and form perfluorinated carboxylic acid resin's monofilm, 16 microns of thickness by forcing machine melting curtain coating; Then the perfluor hotmelt of molecular weight=4.7 ten thousand, IEC=1.44mmol/g (m=6, n=12 in formula I) is coated at 125 ℃ to a surface of perfluorinated sulfonic resin monofilm after melting by curtain coating head by forcing machine, form the high-elastic rete of perfluor tackiness agent, 17 microns of thickness; Perfluorinated carboxylic acid resin's monofilm is introduced, pressing forms the composite membrane of the three-decker of three-decker together simultaneously; Finally, by the perfluorinated sulfonic resin layer hot pressing of FEP fibrous reticulum and composite membrane, form the ion-exchange membrane moving under the super high current densities of enhancement type.
This enhancing composite membrane is hydrolyzed 10-15 hour and makes the transition processing, then double-face spray painting zirconia coating in the 25wt%KOH aqueous solution of 90 ℃; The enhancing composite membrane of handling well is arranged in zero pole span test-type electrolyzer and carries out performance test; Probe temperature is 80 ℃, and NaOH concentration of polymer solution is 30%, and current density is 14kA/m
2.Through the electrolytic experiment of 30 days, electrical performance data is stable, average groove is pressed as 2.73V, mean current efficiency is 99.6%, the resistance to tearing that records film according to the method in GB GB/T 16578.2 is 42N, the folding endurance that records film according to the method in GB GB/T 457 is 3.8, and the bursting strength that records film according to the method in GB GB/T454 is 1.1MPa.
Embodiment 5
By the perfluorinated sulfonic resin of IEC=1.35mmol/g, (in formula II, M is-SO
2f, x=4.1, n=0, m=4) form perfluorinated sulfonic resin monofilm, 135 microns of thickness by forcing machine melting curtain coating; By the perfluorinated carboxylic acid resin of IEC=0.78mmol/g, (in formula II, M is-COOCH
3, x=7.6, n=0, m=3) and form perfluorinated carboxylic acid resin's monofilm, 12 microns of thickness by forcing machine melting curtain coating; Then the perfluor hotmelt of molecular weight=5.9 ten thousand, IEC=1.18mmol/g (m=12, n=10 in formula I) is coated at 175 ℃ to a surface of perfluorinated sulfonic resin monofilm after melting by curtain coating head by forcing machine, form the high-elastic rete of perfluor tackiness agent, 4 microns of thickness; Perfluorinated carboxylic acid resin's monofilm is introduced, pressing forms the composite membrane of the three-decker of three-decker together simultaneously; Finally, by the perfluorinated sulfonic resin layer hot pressing of PEEK fibrous reticulum and composite membrane, form the ion-exchange membrane moving under the super high current densities of enhancement type.
This enhancing composite membrane is hydrolyzed 10-15 hour and makes the transition processing, then double-face spray painting zirconia coating in the 25wt%KOH aqueous solution of 90 ℃; The enhancing composite membrane of handling well is arranged in zero pole span test-type electrolyzer and carries out performance test; Probe temperature is 80 ℃, and NaOH concentration of polymer solution is 30%, and current density is 17kA/m
2.Through the electrolytic experiment of 30 days, electrical performance data is stable, average groove is pressed as 2.78V, mean current efficiency is 99.5%, the resistance to tearing that records film according to the method in GB GB/T 16578.2 is 46N, the folding endurance that records film according to the method in GB GB/T 457 is 3.8, and the bursting strength that records film according to the method in GB GB/T454 is 1.4MPa.
Embodiment 6
By the perfluorinated sulfonic resin of IEC=1.60mmol/g, (in formula II, M is-SO
2f, x=2.8, n=1, m=4) form perfluorinated sulfonic resin monofilm, 80 microns of thickness by forcing machine melting curtain coating; By the perfluorinated carboxylic acid resin of IEC=0.93mmol/g, (in formula II, M is-COOCH
3, x=3.9, n=0, m=5) and form perfluorinated carboxylic acid resin's monofilm, 20 microns of thickness by forcing machine melting curtain coating; Then the perfluor hotmelt of molecular weight=2.7 ten thousand, IEC=1.35mmol/g (m=12, n=12 in formula I) is coated at 145 ℃ to a surface of perfluorinated sulfonic resin monofilm after melting by curtain coating head by forcing machine, form the high-elastic rete of perfluor tackiness agent, 8 microns of thickness; Perfluorinated carboxylic acid resin's monofilm is introduced, pressing forms the composite membrane of the three-decker of three-decker together simultaneously; Finally, by the perfluorinated sulfonic resin layer hot pressing of PFA microporous membrane and composite membrane, form the ion-exchange membrane moving under the super high current densities of enhancement type.
This enhancing composite membrane is hydrolyzed 10-15 hour and makes the transition processing, then double-face spray painting zirconia coating in the 25wt%KOH aqueous solution of 90 ℃; The enhancing composite membrane of handling well is arranged in zero pole span test-type electrolyzer and carries out performance test; Probe temperature is 80 ℃, and NaOH concentration of polymer solution is 30%, and current density is 20kA/m
2.Through the electrolytic experiment of 30 days, electrical performance data is stable, average groove is pressed as 2.80V, mean current efficiency is 99.6%, the resistance to tearing that records film according to the method in GB GB/T 16578.2 is 42N, the folding endurance that records film according to the method in GB GB/T 457 is 3.3, and the bursting strength that records film according to the method in GB GB/T454 is 1.2MPa.
In order to carry out the stripping test of perfluorinated sulfonic acid rete and perfluorocarboxylic acid rete, it is special that to adopt perfluorinated sulfonic resin in embodiment 1 and perfluorinated carboxylic acid resin to prepare respectively thickness be that the monofilm of 200 microns guarantees that film is not pulled off in the time peeling off, and at the high-elastic film of perfluor tackiness agent of middle pressing 10 micron thickness, peel off test according to the degree of 180 in GB/T 2790-1995 peel strength test method, its stripping strength is 54N/cm.