CN113285171A - High-strength meta-aramid diaphragm and preparation method thereof - Google Patents
High-strength meta-aramid diaphragm and preparation method thereof Download PDFInfo
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- CN113285171A CN113285171A CN202110431004.5A CN202110431004A CN113285171A CN 113285171 A CN113285171 A CN 113285171A CN 202110431004 A CN202110431004 A CN 202110431004A CN 113285171 A CN113285171 A CN 113285171A
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- 239000004760 aramid Substances 0.000 title claims abstract description 99
- 229920003235 aromatic polyamide Polymers 0.000 title claims abstract description 91
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims abstract description 54
- 238000001035 drying Methods 0.000 claims abstract description 42
- 239000007864 aqueous solution Substances 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims abstract description 24
- 238000003756 stirring Methods 0.000 claims abstract description 24
- 239000002202 Polyethylene glycol Substances 0.000 claims abstract description 21
- 229920001223 polyethylene glycol Polymers 0.000 claims abstract description 21
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 claims abstract description 19
- 229940018564 m-phenylenediamine Drugs 0.000 claims abstract description 19
- FDQSRULYDNDXQB-UHFFFAOYSA-N benzene-1,3-dicarbonyl chloride Chemical compound ClC(=O)C1=CC=CC(C(Cl)=O)=C1 FDQSRULYDNDXQB-UHFFFAOYSA-N 0.000 claims abstract description 13
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims abstract description 11
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims abstract description 11
- 239000000920 calcium hydroxide Substances 0.000 claims abstract description 11
- 239000002002 slurry Substances 0.000 claims abstract description 9
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 8
- 238000001816 cooling Methods 0.000 claims abstract description 7
- 238000010438 heat treatment Methods 0.000 claims abstract description 6
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 6
- 239000000243 solution Substances 0.000 claims description 43
- 238000001125 extrusion Methods 0.000 claims description 37
- 238000000605 extraction Methods 0.000 claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- 239000008367 deionised water Substances 0.000 claims description 13
- 229910021641 deionized water Inorganic materials 0.000 claims description 13
- 238000007711 solidification Methods 0.000 claims description 5
- 230000008023 solidification Effects 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 3
- 229920006231 aramid fiber Polymers 0.000 abstract description 22
- 230000008569 process Effects 0.000 abstract description 9
- 230000002194 synthesizing effect Effects 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 8
- 239000012528 membrane Substances 0.000 description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 239000011148 porous material Substances 0.000 description 6
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 4
- 238000005266 casting Methods 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000001112 coagulating effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
- C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids
- C08G69/28—Preparatory processes
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
- C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids
- C08G69/32—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids from aromatic diamines and aromatic dicarboxylic acids with both amino and carboxylic groups aromatically bound
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Artificial Filaments (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
Abstract
The invention discloses a strength meta-aramid fiber diaphragm and a preparation method thereof. The preparation method comprises the following steps: step 1: synthesizing meta-aramid pulp: firstly, stirring and dissolving m-phenylenediamine in dimethylacetamide, and then cooling to 0-5 ℃; adding isophthaloyl dichloride, uniformly stirring and gradually heating to 80 ℃; then adding calcium hydroxide and stirring uniformly; finally adding polyethylene glycol and stirring to obtain meta-aramid fiber slurry; step 2: pressurizing and extruding the meta-aramid pulp obtained in the step 1, and stretching the meta-aramid pulp in a dimethylacetamide aqueous solution to form a film; and step 3: sequentially solidifying and extracting in dimethylacetamide aqueous solutions with different concentrations; and 4, step 4: and drying to obtain the high-strength meta-aramid diaphragm. In the preparation method, polyethylene glycol is added in the slurry synthesis process, and then the slurry is stretched into a film in a dimethylacetamide aqueous solution. The preparation method ensures that the arrangement of the meta-aramid molecules is more regular, and the finally formed meta-aramid diaphragm has higher strength.
Description
Technical Field
The invention relates to the technical field of lithium battery diaphragms, in particular to a high-strength meta-aramid diaphragm and a preparation method thereof.
Background
The meta-aramid diaphragm is a high temperature resistant material. The conventional preparation method of the meta-aramid diaphragm is to directly extrude a stretched film after synthesizing meta-aramid pulp. The stretched film is easy to break in the process, the structure is not uniform, the finally manufactured diaphragm is brittle and has low strength, and the safety performance of the lithium battery is not improved when the stretched film is applied to the diaphragm.
Disclosure of Invention
The invention aims to provide a preparation method of high-strength meta-aramid aiming at the technical defects of easy breakage and uneven structure in the existing preparation method of the meta-aramid diaphragm.
The invention also provides the high-strength meta-aramid diaphragm prepared by the preparation method.
The technical scheme adopted for realizing the purpose of the invention is as follows:
a high-strength meta-aramid diaphragm and a preparation method thereof comprise the following steps:
step 1: synthesis of meta-aramid pulp
Firstly, stirring and dissolving m-phenylenediamine in dimethylacetamide, and then cooling to 0-5 ℃ to obtain a solution A;
then adding isophthaloyl dichloride into the solution A, uniformly stirring, and gradually heating to 60-90 ℃ to obtain a solution B; the molar ratio of m-phenylenediamine to isophthaloyl chloride is 1: 1;
then, adding calcium hydroxide into the solution B and uniformly stirring to obtain a solution C; in the above step, the ratio of the mass of dimethylacetamide, the mass of calcium hydroxide and the total mass of m-phenylenediamine and isophthaloyl dichloride is (50-60): (5-10): (35-40);
finally, adding polyethylene glycol into the solution C, and stirring for 30-45min to obtain meta-aramid slurry; the mass ratio of the neutralized polyethylene glycol in the solution C is (80-95): (5-20);
step 2: pressurizing and extruding the meta-aramid pulp obtained in the step 1, and stretching the meta-aramid pulp in a dimethylacetamide aqueous solution to form a film;
and step 3: sequentially solidifying and extracting in dimethylacetamide aqueous solutions with different concentrations;
and 4, step 4: and drying to obtain the high-strength meta-aramid diaphragm.
In the step 2 of the technical scheme, a meta-aramid film making device is used; the meta-aramid film making device comprises a pressure extrusion tank, a receiving roller, a buffer roller, a stretching roller and a solution tank filled with a dimethylacetamide aqueous solution; the extrusion outlet of the pressurized extrusion tank, the receiving roller, the buffer roller and the stretching roller are all arranged in the solution tank and are positioned below the liquid level of the dimethylacetamide aqueous solution; and the meta-aramid pulp which is extruded by the extrusion opening of the extrusion tank under pressure sequentially passes through the receiving roller, the buffer roller and the stretching roller to be stretched into a film. The extrusion temperature of the pressure extrusion can is 35-60 ℃; the temperature of the dimethylacetamide aqueous solution is 30-55 ℃; the mass concentration of the dimethylacetamide aqueous solution is 60-80%. The width of the meta-aramid extruded from the extrusion opening of the pressure extrusion tank is 700-1200mm, and the thickness of the meta-aramid is 25-40 mu m; the linear speed of the receiving roller is 8-12 m/min; the linear speed of the buffer roller is 15-20 m/min; the linear speed of the stretching roller is 22-30 m/min.
In the step 3 of the technical scheme, the solidification and extraction process sequentially passes through 10 extraction tanks; wherein the mass ratio of dimethylacetamide to deionized water in the first extraction tank is 3: 2; the mass ratio of dimethylacetamide to deionized water in the second extraction tank is 1: 1; the mass ratio of dimethylacetamide to deionized water in the third extraction tank is 2: 3; the rest of the extraction tanks are filled with deionized water.
In the step 4 of the technical scheme, a step drying method is adopted, wherein the drying temperature of the first stage is 40-60 ℃, and the drying time is 7-12 s; the second stage drying temperature is 50-70 ℃, and the drying time is 5-8 s; the third stage drying temperature is 60-80 deg.C, and drying time is 10-15 s.
In another aspect of the invention, the high-strength meta-aramid diaphragm prepared by the preparation method is applied.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the preparation method of the high-strength meta-aramid diaphragm, when meta-aramid slurry is synthesized, polyethylene glycol is added and used, the polyethylene glycol has an ether oxygen unshared electron pair, has strong affinity to hydrogen bonds, can form a complex with a plurality of organic low-molecular compounds and polymers, and can reduce the hydrogen bonds among the aramid fibers when the polyethylene glycol acts on the meta-aramid fibers, so that the aramid fibers are loose, and the meta-aramid fibers have better plasticity in a later film forming process. In addition, the polyethylene glycol is dissolved in water, but the extraction speed in the dimethylacetamide aqueous solution is slow, so that the diaphragm can have sufficient time to form the aperture, the aperture is more three-dimensional, and the strength of the diaphragm is improved
2. According to the preparation method of the high-strength meta-aramid diaphragm, the meta-aramid after the polyethylene glycol is added is flexible in a dimethylacetamide aqueous solution with a certain concentration, and has very strong plasticity. Therefore, the stretching film formation is carried out in a dimethylacetamide aqueous solution in the film formation process, and the method is applied to ensure that the arrangement of molecules in the aramid fiber in the film is relatively regular.
3. The high-strength meta-aramid diaphragm provided by the invention has the advantages that the meta-aramid molecules are regularly and uniformly arranged, the pore diameter is three-dimensional, and the tensile strength of the aramid diaphragm is favorably enhanced.
Drawings
FIG. 1 is a scanning electron micrograph of the high strength meta-aramid separator prepared in example 1;
fig. 2 is a scanning electron microscope image of the meta-aramid separator prepared in comparative example 1.
Fig. 3 is a schematic structural diagram of a m-aramid film-making device.
Wherein, 1-extrusion can, 1-extrusion outlet, 2-receiving roller, 3-buffer roller, 4-stretching roller and 5-solution tank.
Detailed Description
The present invention will be described in further detail with reference to specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
A preparation method of a high-strength meta-aramid diaphragm comprises the following steps:
step 1: synthesis of meta-aramid pulp
Firstly, introducing nitrogen into a reaction tank for protection, adding dimethylacetamide, then adding m-phenylenediamine, stirring for 20min to completely dissolve the m-phenylenediamine, and cooling to 0 ℃ to obtain a solution A;
then adding isophthaloyl dichloride with the molar quantity equal to that of m-phenylenediamine into the solution A, stirring for 20min, and gradually heating to 80 ℃ (wherein the temperature rise process is about 80min) to obtain a solution B;
then, adding calcium hydroxide into the solution B, and stirring for 30min to obtain a solution C;
in the step, the mass part of the dimethylacetamide is 60 parts; the total mass portion of the m-phenylenediamine and the isophthaloyl dichloride is 35 portions; the mass portion of the calcium hydroxide is 5 portions;
finally, adding polyethylene glycol into the solution C, and stirring for 30min to obtain meta-aramid slurry; the mass part ratio of the solution C to the polyethylene glycol is 80: 20;
step 2: pressurizing and extruding the meta-aramid pulp obtained in the step 1, and stretching the meta-aramid pulp in a dimethylacetamide aqueous solution to form a film; this step uses a meta-aramid film-making device.
As shown in fig. 3, the m-aramid film-forming apparatus includes a pressure extrusion tank 1, a receiving roller 2, a buffer roller 3, a stretching roller 4, and a solution tank 5 containing an aqueous solution of dimethylacetamide; the extrusion outlet 1-1 of the pressurized extrusion tank 1, the receiving roller 2, the buffer roller 3, and the stretching roller 4 are all disposed in the solution tank 5 and below the liquid level of the dimethylacetamide aqueous solution. The meta-aramid pulp which is extruded by the extrusion opening 1-1 of the extrusion tank 1 in a pressurizing way sequentially passes through the receiving roller 2, the buffer roller 3 and the stretching roller 4 to be stretched into a film.
The extrusion temperature of the pressure extrusion tank 1 is 35 ℃; the temperature of the dimethylacetamide aqueous solution is 35 ℃; the concentration of the dimethylacetamide aqueous solution is 60%. The width of the meta-aramid extruded from the extrusion opening 1-1 of the pressure extrusion tank 1 is 700mm, and the thickness of the meta-aramid is 25 micrometers; the linear speed of the receiving roller 2 is 8 m/min; the linear speed of the buffer roller 3 is 15 m/min; the linear speed of the stretching roller 4 was 22 m/min.
And step 3: sequentially solidifying and extracting in dimethylacetamide aqueous solutions with different concentrations; the solidification and extraction process sequentially passes through 10 extraction tanks, and the depth of each tank is 1 m; wherein the mass ratio of dimethylacetamide to deionized water in the first extraction tank is 3: 2; the mass ratio of dimethylacetamide to deionized water in the second extraction tank is 1: 1; the mass ratio of dimethylacetamide to deionized water in the third extraction tank is 2: 3; the rest of the extraction tanks are filled with deionized water. Allowing the meta-aramid to pass through each groove, and sequentially extracting with three coagulating baths and deionized water with different concentrations.
And 4, step 4: drying to obtain the high-strength meta-aramid fiber diaphragm, and adopting a step drying method, wherein the drying temperature in the first stage is 40 ℃, the air exhaust frequency is 13Hz, the air inlet frequency is 14Hz, and the drying time is 7 s; in the second stage, the drying temperature is 50 ℃, the air exhaust frequency is 15Hz, the air inlet frequency is 16Hz, and the drying time is 5 s; in the third stage, the drying temperature is 60 ℃, the air exhaust frequency is 15Hz, the air inlet frequency is 16Hz, and the drying time is 10 s.
The scanning electron microscope image of the prepared high-strength meta-aramid diaphragm is shown in fig. 1. In the figure, aramid fibers are uniformly distributed, and the pore diameter is three-dimensional. The structural characteristic is beneficial to enhancing the tensile strength of the aramid fiber membrane.
Comparative example 1
Comparative example 1 compared with example 1, the difference is that in step 1, dimethyl carbonate is added into the solution C and stirred for 30min to obtain meta-aramid pulp. The other condition parameters were kept consistent with example 1.
The scanning electron microscope image of the prepared aramid fiber membrane is shown in fig. 2. In the figure, aramid molecules are disordered and have larger pore diameters. This structure reduces the overall strength of the separator.
As can be seen from comparison between FIG. 1 and FIG. 2, the pore size in FIG. 1 is in the range of 0.04 to 0.1 μm, and the pore size in FIG. 2 is in the range of 0.7 to 1.2. mu.m. Therefore, the high-strength m-aramid diaphragm aramid fiber prepared in the example 1 is uniform in distribution, small in pore size and three-dimensional.
Compared with the figure 1 and the figure 2, the arrangement of aramid molecules in the aramid fiber membrane prepared from the m-aramid fiber sizing agent added with polyethylene glycol is more regular. The polyethylene glycol has an ether oxygen unshared electron pair, has strong affinity to hydrogen bonds, can form a complex with a plurality of organic low-molecular compounds and polymers, and can reduce the hydrogen bonds among the aramid fibers by the action of the polyethylene glycol on the meta-aramid fibers, so that the aramid fibers are loose and easily form a queuing state. Therefore, after the polyethylene glycol is added, the meta-aramid fiber shows flexibility in a dimethylacetamide aqueous solution with a certain concentration, and has very strong plasticity. And (3) stretching the membrane in a dimethylacetamide aqueous solution to form a membrane, wherein the arrangement of molecules in the aramid fiber in the membrane is regular, and then extracting and curing are carried out to finally form the high-strength meta-aramid fiber membrane.
Comparative example 2
Comparative example 2 is different from example 1 in that a casting method is used to form a film in step 2.
The casting method comprises the following film making processes:
filtering the meta-aramid pulp synthesized in the step 1 in the example 1 at room temperature, and vacuumizing and defoaming for 3 hours; then the mixture is sent to a casting nozzle to cast on a steel belt by pressure, and is dried by hot air at 150 ℃ to form a meta-aramid cast film; cooling to 30 ℃ after stripping.
The condition parameters in the subsequent steps were kept the same as those in steps 3 and 4 in example 1.
Example 2
A high-strength meta-aramid diaphragm and a preparation method thereof comprise the following steps:
step 1: synthesis of meta-aramid pulp
Firstly, introducing nitrogen into a reaction tank for protection, adding dimethylacetamide, then adding m-phenylenediamine, stirring for 20min to completely dissolve the m-phenylenediamine, and cooling to 3 ℃ to obtain a solution A;
then adding isophthaloyl dichloride with the molar quantity equal to that of m-phenylenediamine into the solution A, stirring for 20min, and gradually heating to 80 ℃ (wherein the temperature rise process is about 80min) to obtain a solution B;
then, adding calcium hydroxide into the solution B, and stirring for 30min to obtain a solution C;
in the above step, the mass portion of the dimethylacetamide is 55 portions; the total mass portion of the m-phenylenediamine and the isophthaloyl dichloride is 37 portions; the mass part of the calcium hydroxide is 8 parts;
finally, adding polyethylene glycol into the solution C, and stirring for 30min to obtain meta-aramid slurry; the mass part ratio of the solution C to the polyethylene glycol is 90: 10;
step 2: pressurizing and extruding the meta-aramid pulp obtained in the step 1, and stretching the meta-aramid pulp in a dimethylacetamide aqueous solution to form a film; the same apparatus for producing a m-aramid film as in example 1 was used in this step.
The extrusion temperature of the pressure extrusion tank 1 is 45 ℃; the temperature of the dimethylacetamide aqueous solution is 45 ℃; the concentration of the dimethylacetamide aqueous solution was 70%. The width of the meta-aramid extruded from the extrusion opening 1-1 of the pressure extrusion tank 1 is 900mm, and the thickness of the meta-aramid is 30 micrometers; the linear speed of the receiving roller 2 is 10 m/min; the linear speed of the buffer roller 3 is 18 m/min; the linear speed of the stretching roller 4 was 25 m/min.
And step 3: sequentially solidifying and extracting in dimethylacetamide aqueous solutions with different concentrations; the solidification extraction process was the same as in step 3 of example 1.
And 4, step 4: drying to obtain the high-strength meta-aramid fiber diaphragm, and adopting a step drying method, wherein the drying temperature in the first stage is 50 ℃, the air exhaust frequency is 13Hz, the air inlet frequency is 14Hz, and the drying time is 10 s; in the second stage, the drying temperature is 60 ℃, the air exhaust frequency is 15Hz, the air inlet frequency is 16Hz, and the drying time is 6 s; in the third stage, the drying temperature is 70 ℃, the air exhaust frequency is 15Hz, the air inlet frequency is 16Hz, and the drying time is 13 s.
Example 3
A high-strength meta-aramid diaphragm and a preparation method thereof comprise the following steps:
step 1: synthesis of meta-aramid pulp
Firstly, introducing nitrogen into a reaction tank for protection, adding dimethylacetamide, then adding m-phenylenediamine, stirring for 20min to completely dissolve the m-phenylenediamine, and cooling to 5 ℃ to obtain a solution A;
then adding isophthaloyl dichloride with the molar quantity equal to that of m-phenylenediamine into the solution A, stirring for 20min, and gradually heating to 80 ℃ (wherein the temperature rise process is about 80min) to obtain a solution B;
then, adding calcium hydroxide into the solution B, and stirring for 30min to obtain a solution C;
in the step, the mass part of the dimethylacetamide is 50 parts; the total mass portion of the m-phenylenediamine and the isophthaloyl dichloride is 40 portions; the mass portion of the calcium hydroxide is 10 portions;
finally, adding polyethylene glycol into the solution C, and stirring for 30min to obtain meta-aramid slurry; the mass part ratio of the solution C to the polyethylene glycol is 95: 5;
step 2: pressurizing and extruding the meta-aramid pulp obtained in the step 1, and stretching the meta-aramid pulp in a dimethylacetamide aqueous solution to form a film; the same apparatus for producing a m-aramid film as in example 1 was used in this step.
The extrusion temperature of the pressure extrusion tank 1 is 60 ℃; the temperature of the dimethylacetamide aqueous solution is 60 ℃; the concentration of the dimethylacetamide aqueous solution is 80%. The width of the meta-aramid extruded from the extrusion opening 1-1 of the pressure extrusion tank 1 is 1200mm, and the thickness of the meta-aramid is 40 micrometers; the linear speed of the receiving roller 2 is 12 m/min; the linear speed of the buffer roller 3 is 20 m/min; the linear speed of the stretching roller 4 was 30 m/min.
And step 3: sequentially solidifying and extracting in dimethylacetamide aqueous solutions with different concentrations; the solidification extraction process was the same as in step 3 of example 1.
And 4, step 4: drying to obtain the high-strength meta-aramid fiber diaphragm, and adopting a step drying method, wherein the drying temperature in the first stage is 60 ℃, the air exhaust frequency is 13Hz, the air inlet frequency is 14Hz, and the drying time is 12 s; in the second stage, the drying temperature is 70 ℃, the air exhaust frequency is 15Hz, the air inlet frequency is 16Hz, and the drying time is 8 s; in the third stage, the drying temperature is 80 ℃, the air exhaust frequency is 15Hz, the air inlet frequency is 16Hz, and the drying time is 15 s.
The performance parameters of the m-aramid separator prepared in examples 1 to 3 and comparative examples 1 to 2 are shown in the following table:
as can be seen from the table above, the m-aramid separator prepared in example 1 has better air permeability and a reduced shrinkage at 170 ℃. More importantly, the tensile strength and elongation of the meta-aramid separator prepared in example 1 were significantly improved compared to the meta-aramid separator prepared in comparative example 1.
As can be seen from the above table, the high-strength m-aramid separator prepared in example 1 has significantly improved shrinkage, tensile strength, and elongation compared to the m-aramid separator prepared in comparative example 2. The stretching film-forming method by using the meta-aramid film-forming device is compared with the casting film-forming method, and the prepared diaphragm has better performance.
The high strength meta-aramid membranes of the invention were prepared with process parameter adjustments according to the teachings of the invention and exhibited substantially the same performance as example 1.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A preparation method of a high-strength meta-aramid diaphragm is characterized by comprising the following steps: the method comprises the following steps:
step 1: synthesis of meta-aramid pulp
Firstly, stirring and dissolving m-phenylenediamine in dimethylacetamide, and then cooling to 0-5 ℃ to obtain a solution A;
then adding isophthaloyl dichloride into the solution A, uniformly stirring, and gradually heating to 60-90 ℃ to obtain a solution B;
then, adding calcium hydroxide into the solution B and uniformly stirring to obtain a solution C;
finally, adding polyethylene glycol into the solution C, and stirring for 30-45min to obtain meta-aramid slurry;
step 2: pressurizing and extruding the meta-aramid pulp obtained in the step 1, and stretching the meta-aramid pulp in a dimethylacetamide aqueous solution to form a film;
and step 3: sequentially solidifying and extracting in dimethylacetamide aqueous solutions with different concentrations;
and 4, step 4: and drying to obtain the high-strength meta-aramid diaphragm.
2. The method of claim 1, wherein: in the step 1, the molar ratio of m-phenylenediamine to isophthaloyl chloride is 1: 1.
3. The method of claim 2, wherein: the proportion of the mass of the dimethylacetamide, the mass of the calcium hydroxide and the total mass of the m-phenylenediamine and the isophthaloyl dichloride is (50-60): (5-10): (35-40).
4. The method of claim 3, wherein: the mass ratio of the solution C to the polyethylene glycol is (80-95): (5-20).
5. The method of claim 1, wherein: in the step 2, a meta-aramid film making device is used for making a film, and the meta-aramid film making device comprises a pressure extrusion tank, a receiving roller, a buffer roller, a stretching roller and a solution tank filled with a dimethylacetamide aqueous solution; the extrusion outlet of the pressurized extrusion tank, the receiving roller, the buffer roller and the stretching roller are all arranged in the solution tank and are positioned below the liquid level of the dimethylacetamide aqueous solution; and the meta-aramid pulp which is extruded by the extrusion opening of the extrusion tank under pressure sequentially passes through the receiving roller, the buffer roller and the stretching roller to be stretched into a film.
6. The method of claim 5, wherein: the extrusion temperature of the pressure extrusion can is 35-60 ℃; the temperature of the dimethylacetamide aqueous solution is 30-55 ℃; the mass concentration of the dimethylacetamide aqueous solution is 60-80%.
7. The method of claim 5, wherein: the width of the meta-aramid extruded from the extrusion opening of the pressure extrusion tank is 700-1200mm, and the thickness of the meta-aramid is 25-40 mu m; the linear speed of the receiving roller is 8-12 m/min; the linear speed of the buffer roller is 15-20 m/min; the linear speed of the stretching roller is 22-30 m/min.
8. The method of claim 1, wherein: in the step 3, the solidification and extraction process sequentially passes through 10 extraction tanks; wherein the mass ratio of dimethylacetamide to deionized water in the first extraction tank is 3: 2; the mass ratio of dimethylacetamide to deionized water in the second extraction tank is 1: 1; the mass ratio of dimethylacetamide to deionized water in the third extraction tank is 2: 3; the rest of the extraction tanks are filled with deionized water.
9. The method of claim 1, wherein: step drying method is adopted in step drying step 4, wherein the first stage drying temperature is 40-60 ℃, and the drying time is 7-12 s; the second stage drying temperature is 50-70 ℃, and the drying time is 5-8 s; the third stage drying temperature is 60-80 deg.C, and drying time is 10-15 s.
10. High-strength meta-aramid separator obtained by the method according to any one of claims 1 to 9.
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